CCing heads, my experience so far...
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- cgrey8
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CCing heads, my experience so far...
I started a thread over on EECTuning.org about my experience ccing my GT40p heads. You'd think it would be fairly straight forward, but not as straight forward as I'd hoped. I forgot I didn't create a parallel thread over here disucssing my findings. For anybody interested, here's the thread:
GT40p chamber volume not what I expected
GT40p chamber volume not what I expected
...Always Somethin'
89 Ranger Supercab, 331, ported GT40p heads w/1.6RRs, Crane Powermax 2020 cam, ported Explorer lower, FMS Explorer (GT40p) headers, aftermarket T5 'Z-Spec', 8.8" rear w/3.27s, Powertrax Locker, A9L w/Moates QuarterHorse, Innovate LC-1, James Duff traction bars, iDelta DC Fan controller
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89 Ranger Supercab, 331, ported GT40p heads w/1.6RRs, Crane Powermax 2020 cam, ported Explorer lower, FMS Explorer (GT40p) headers, aftermarket T5 'Z-Spec', 8.8" rear w/3.27s, Powertrax Locker, A9L w/Moates QuarterHorse, Innovate LC-1, James Duff traction bars, iDelta DC Fan controller
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Re: CCing heads, my experience so far...
I read through that thread last night. Pretty interesting. I never really thought of the effects of air tumble and swirl when a piston has 4 valve reliefs vs 2 valve reliefs. You've definitely looked at every last tiny detail.
So based on your findings of the head CCs to be a tad larger than you were planning for have you decided to get the heads milled down a bit or are you going to change pistons or what are your thoughts at this time?
So based on your findings of the head CCs to be a tad larger than you were planning for have you decided to get the heads milled down a bit or are you going to change pistons or what are your thoughts at this time?
92 302 Ranger - sold
94 302 Ranger AWD - sold
07 BMW 335xi - tuned, boost turned up, E85 - sold
04 911 TT - to many mods to list. Over 600 All Wheel HP on pump gas - sold
2015 Coyote - daily driver
03 Cobra - 2.3 TVS on a built 12:1 CR motor with ported heads, cams, long tubes etc.
MD Racing Lean Protection Module
E85
Tuned by MD Racing
https://www.youtube.com/c/MalcolmV8
94 302 Ranger AWD - sold
07 BMW 335xi - tuned, boost turned up, E85 - sold
04 911 TT - to many mods to list. Over 600 All Wheel HP on pump gas - sold
2015 Coyote - daily driver
03 Cobra - 2.3 TVS on a built 12:1 CR motor with ported heads, cams, long tubes etc.
MD Racing Lean Protection Module
E85
Tuned by MD Racing
https://www.youtube.com/c/MalcolmV8
- cgrey8
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Re: CCing heads, my experience so far...
To get the compression and quench I'm looking for, I'll need to pop the pistons out of the hole (piston tops above the deck) about .004". That's just a matter of decking the block enough to get that right. But that poses other problems. If I deck the block or heads too much, then I would have to revisit the lower intake and deck it also to fit the now-narrower head surfaces. So are the options?
Standard stroker pistons have a compression height of 1.165" which puts the pistons in the hole a bit. The assumption is the person will be milling off the decks to doing an align-bore (not align-hone) and so the 1.165" is what most people want. But since I'm trying to minimize the amount of decking, I'm going with 1.175" compression height pistons which oddly are not as common as I would've expected.
.010" off the heads to get them true. One head had a twist. The other had a dip in the center. To get them both flat, true, and equal to each other, they had to take .010" off them.
.007" thinner head gasket. Stock Explorer gaskets measure out to .047" or at least the ones on my engine did. I'm replacing them with thinner .039" gaskets to get the compression and quench I want.
The deck will come down to get the pistons out of the holes. Design deck height is 8.200" for 302 Windsors, but many stock blocks end up being slightly higher than that and mine is no exception. So to get the pistons to pop and to true the block will probably require .005-.008" off.
But all-n-all, it looks like I'll be able to do what I need to do without having to deck the lower intake down which isn't the end of the world, but is another $200 or so more that I was hoping to avoid.
Standard stroker pistons have a compression height of 1.165" which puts the pistons in the hole a bit. The assumption is the person will be milling off the decks to doing an align-bore (not align-hone) and so the 1.165" is what most people want. But since I'm trying to minimize the amount of decking, I'm going with 1.175" compression height pistons which oddly are not as common as I would've expected.
.010" off the heads to get them true. One head had a twist. The other had a dip in the center. To get them both flat, true, and equal to each other, they had to take .010" off them.
.007" thinner head gasket. Stock Explorer gaskets measure out to .047" or at least the ones on my engine did. I'm replacing them with thinner .039" gaskets to get the compression and quench I want.
The deck will come down to get the pistons out of the holes. Design deck height is 8.200" for 302 Windsors, but many stock blocks end up being slightly higher than that and mine is no exception. So to get the pistons to pop and to true the block will probably require .005-.008" off.
But all-n-all, it looks like I'll be able to do what I need to do without having to deck the lower intake down which isn't the end of the world, but is another $200 or so more that I was hoping to avoid.
Last edited by cgrey8 on Sat Apr 09, 2011 1:55 pm, edited 1 time in total.
...Always Somethin'
89 Ranger Supercab, 331, ported GT40p heads w/1.6RRs, Crane Powermax 2020 cam, ported Explorer lower, FMS Explorer (GT40p) headers, aftermarket T5 'Z-Spec', 8.8" rear w/3.27s, Powertrax Locker, A9L w/Moates QuarterHorse, Innovate LC-1, James Duff traction bars, iDelta DC Fan controller
Admin of EECtuning.org
89 Ranger Supercab, 331, ported GT40p heads w/1.6RRs, Crane Powermax 2020 cam, ported Explorer lower, FMS Explorer (GT40p) headers, aftermarket T5 'Z-Spec', 8.8" rear w/3.27s, Powertrax Locker, A9L w/Moates QuarterHorse, Innovate LC-1, James Duff traction bars, iDelta DC Fan controller
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Re: CCing heads, my experience so far...
I would think you should mill the heads down rather than the block and keep the pistons from popping out the block in case you ever switch heads. Perhaps your goals change down the road or maybe this setup doesn't work exactly as you expect and you decide to use different heads to get what you want. Just something to think about.
92 302 Ranger - sold
94 302 Ranger AWD - sold
07 BMW 335xi - tuned, boost turned up, E85 - sold
04 911 TT - to many mods to list. Over 600 All Wheel HP on pump gas - sold
2015 Coyote - daily driver
03 Cobra - 2.3 TVS on a built 12:1 CR motor with ported heads, cams, long tubes etc.
MD Racing Lean Protection Module
E85
Tuned by MD Racing
https://www.youtube.com/c/MalcolmV8
94 302 Ranger AWD - sold
07 BMW 335xi - tuned, boost turned up, E85 - sold
04 911 TT - to many mods to list. Over 600 All Wheel HP on pump gas - sold
2015 Coyote - daily driver
03 Cobra - 2.3 TVS on a built 12:1 CR motor with ported heads, cams, long tubes etc.
MD Racing Lean Protection Module
E85
Tuned by MD Racing
https://www.youtube.com/c/MalcolmV8
- cgrey8
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Re: CCing heads, my experience so far...
The other target I'm trying to hit is a .035" or less quench. With a .039" gasket, I have to come out of the holes some. The next smallest gasket I could find was one in the high .020s and they were unbelievably expensive. Stock head gaskets were about $20 each. These .039" gaskets were $40/each. The super thin gaskets were something like $80/each and I just couldn't justify that increase when the .039s will get me where I need to be with options for the future. Add to that, the block will need to be decked some anyway. As mentioned earlier, one head had a seasoning twist, the other with a dip...both perfectly normal things for cast iron to do after it's been run a few years. Cast Iron Blocks do the same thing. So to get the decks perfectly square with the bores, they have to get decked some. Usually it doesn't require more than .002-.004" to get the block true. But since my block, due to engineering tolerances is already over 8.200" by a few thousands, they'll probably be taking .006-.008" off. I asked the machinist if there was any issues with doing this. He said most people get zero-decking just because that's easier for them to work with. But people that are looking for a tight quench on affordable gaskets pretty much have to pop the pistons. And since he's also a believer in making heavy use of quench in a daily driven engine, he supported my approach and said for my purposes, it'll work just fine.
The Dynamic Compression Ratio I'm aiming for is around 8.3-8.4:1. Pretty much everything I've read says that 8.5:1 DCR is about the highest you can go with premium octane pump gas without special considerations. Aiming for the 8.4:1 DCR range with the cam I'm using puts the static compression ratio (SCR), the compression ratio number most people are familiar with, at ~9.9:1. I could probably round and call it 10:1. Without the tight quench, this would pretty much guarantee I'd be stuck on premium pump gas or some high concentration of ethanol. But with the tight quench, maintaining a working EGR, and EEC tuning, I'll likely be able to get away with mid-grade and for daily driving. And for long trips where I don't plan on any WOTs, I should be able to run regular 87. The intention with the high compression is to get as much efficiency out of the engine as possible to improve fuel economy. It has the side-effect of also producing more power on higher octane fuel which is a nice icing for the cake. If we ever get an E85 station near me, that'll be a nice added bonus that's built-into the engine.
But yeah it has occurred to me that while I'm following all the rules, things may still end up different than I expect...in other words, even with premium pump gas the engine may still ping the heads off. If I didn't have a 2nd engine, then I probably would be a bit more conservative.
Since the only thing I expect might not work well would be too high of a compression ratio, I'm moving ahead flirting with the 8.5 DCR limit. If that turns out to be the case that I can't NOT run premium, then I'll run premium and suck-it-up as a learning experience. But if I get tired of that, the very conservative cam I have can easily be replaced with a slightly more aggressive cam. While I wouldn't do the cam swap for the purposes of more power, I'd be doing it to lower the Dynamic Compression Ratio. Very radical cams lower DCR so badly that you HAVE to run higher SCRs with those engines. That's why it isn't unheard of to hear about people building 11:1 SCR engines and still run street gas although an 11:1 SCR engine with my setup would not run even with E85. It's because their cams are so radical that the DCR ends up being at or below that 8.5:1 threshold. And a cam swap is certainly easier than machine work.
The event that I would need to do something about excessive ping, I've already looked ahead at what cams would be good options. The cam I'd likely go with would be a Comp XE264HR14 which is only a category above my cam...slightly less cylinder filling so slightly less off-idle torque, but the less cylinder filling would give me a DCR just just shy of 8.2DCR...well within the capabilities of premium pump gas. If I wanted to ensure I could run regular 87 octane pump gas, I'd go up to the next category cam Comp XE274HR12. That's the same cam 87Ranger runs in his 347 twin turbo. With that cam, I'd have a dead-even 8.00 DCR. Now I'd loose significantly more off-idle torque (my whole reason for building the engine) but it would let me drive the 331 with cheaper gas. But the hope is I've done my homework, got the tight quench, working EGR, and low enough DCR that it won't be an issue and I'll have a very strong off-idle 331 that will rival with a NA 347 running that XE274HR12 from idle-4000. Above that, the 347 with that more performance-oriented cam and larger displacement would easily out-produce what I'd be doing. But since I spend 99% of my time under 3000RPMs and I never race, this combination just works best for what I'm trying to do.
But lets say I do decide in the future that I want something even bigger and badder, or I just happen across a set of aluminum heads I can't turn down. I'll have the 302 I'm driving right now to do that work to. I bought the 2nd engine so I could take my time, do the research, and get things done as right as I could building the engine vs being under a time constraint to get the engine back together and the truck back running again. I also can't complain that the 2nd engine only cost me $250, the gas and a Saturday to drive to North Carolina to get it. But once the 331 is running, it's an added bonus that I'll have it to build for a future project. Or it'll just be a parts truck.
The Dynamic Compression Ratio I'm aiming for is around 8.3-8.4:1. Pretty much everything I've read says that 8.5:1 DCR is about the highest you can go with premium octane pump gas without special considerations. Aiming for the 8.4:1 DCR range with the cam I'm using puts the static compression ratio (SCR), the compression ratio number most people are familiar with, at ~9.9:1. I could probably round and call it 10:1. Without the tight quench, this would pretty much guarantee I'd be stuck on premium pump gas or some high concentration of ethanol. But with the tight quench, maintaining a working EGR, and EEC tuning, I'll likely be able to get away with mid-grade and for daily driving. And for long trips where I don't plan on any WOTs, I should be able to run regular 87. The intention with the high compression is to get as much efficiency out of the engine as possible to improve fuel economy. It has the side-effect of also producing more power on higher octane fuel which is a nice icing for the cake. If we ever get an E85 station near me, that'll be a nice added bonus that's built-into the engine.
But yeah it has occurred to me that while I'm following all the rules, things may still end up different than I expect...in other words, even with premium pump gas the engine may still ping the heads off. If I didn't have a 2nd engine, then I probably would be a bit more conservative.
Since the only thing I expect might not work well would be too high of a compression ratio, I'm moving ahead flirting with the 8.5 DCR limit. If that turns out to be the case that I can't NOT run premium, then I'll run premium and suck-it-up as a learning experience. But if I get tired of that, the very conservative cam I have can easily be replaced with a slightly more aggressive cam. While I wouldn't do the cam swap for the purposes of more power, I'd be doing it to lower the Dynamic Compression Ratio. Very radical cams lower DCR so badly that you HAVE to run higher SCRs with those engines. That's why it isn't unheard of to hear about people building 11:1 SCR engines and still run street gas although an 11:1 SCR engine with my setup would not run even with E85. It's because their cams are so radical that the DCR ends up being at or below that 8.5:1 threshold. And a cam swap is certainly easier than machine work.
The event that I would need to do something about excessive ping, I've already looked ahead at what cams would be good options. The cam I'd likely go with would be a Comp XE264HR14 which is only a category above my cam...slightly less cylinder filling so slightly less off-idle torque, but the less cylinder filling would give me a DCR just just shy of 8.2DCR...well within the capabilities of premium pump gas. If I wanted to ensure I could run regular 87 octane pump gas, I'd go up to the next category cam Comp XE274HR12. That's the same cam 87Ranger runs in his 347 twin turbo. With that cam, I'd have a dead-even 8.00 DCR. Now I'd loose significantly more off-idle torque (my whole reason for building the engine) but it would let me drive the 331 with cheaper gas. But the hope is I've done my homework, got the tight quench, working EGR, and low enough DCR that it won't be an issue and I'll have a very strong off-idle 331 that will rival with a NA 347 running that XE274HR12 from idle-4000. Above that, the 347 with that more performance-oriented cam and larger displacement would easily out-produce what I'd be doing. But since I spend 99% of my time under 3000RPMs and I never race, this combination just works best for what I'm trying to do.
But lets say I do decide in the future that I want something even bigger and badder, or I just happen across a set of aluminum heads I can't turn down. I'll have the 302 I'm driving right now to do that work to. I bought the 2nd engine so I could take my time, do the research, and get things done as right as I could building the engine vs being under a time constraint to get the engine back together and the truck back running again. I also can't complain that the 2nd engine only cost me $250, the gas and a Saturday to drive to North Carolina to get it. But once the 331 is running, it's an added bonus that I'll have it to build for a future project. Or it'll just be a parts truck.
...Always Somethin'
89 Ranger Supercab, 331, ported GT40p heads w/1.6RRs, Crane Powermax 2020 cam, ported Explorer lower, FMS Explorer (GT40p) headers, aftermarket T5 'Z-Spec', 8.8" rear w/3.27s, Powertrax Locker, A9L w/Moates QuarterHorse, Innovate LC-1, James Duff traction bars, iDelta DC Fan controller
Admin of EECtuning.org
89 Ranger Supercab, 331, ported GT40p heads w/1.6RRs, Crane Powermax 2020 cam, ported Explorer lower, FMS Explorer (GT40p) headers, aftermarket T5 'Z-Spec', 8.8" rear w/3.27s, Powertrax Locker, A9L w/Moates QuarterHorse, Innovate LC-1, James Duff traction bars, iDelta DC Fan controller
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- cgrey8
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Re: CCing heads, my experience so far...
BTW, just for some reference of comparison, when I calculated what the Explorer 302's quench and compression were, they were...well pathetic.
In stock form, the engine I'm doing all the work to had the pistons in the holes .015-.017" and the stock gaskets were .047" thick (same as the OEM replacements from AutoZone). Between those two, that's OVER .060" quench. Anything .060" or higher yields NO benefits at deterring detonation. You have to be at or below .050" to begin to benefit from quench. Most people aim for around .040" quench and ideal quench is .035" on most engines. Some engine builders have gotten positive results on older cast heads that were particularly known for their low RPM detonation tendencies with quench in the .025-.030" range. I'm aiming for quench in the .030-.035" range.
I had to guess at the stock piston's dish ccs to get stock compression ratios. I'm guesstimating the pistons were in the 9cc range. Aftermarket Keith Black flat top dual-lash pistons are 11.5cc so I estimated the stock pistons lower because aftermarket pistons generally have larger diameter lashes cut a little deeper to satisfy larger diameter aftermarket valves and higher lift cams. With the stock Explorer cam, stock gasket, measured piston compression heights, guessed-at stock head chamber ccs (I didn't perfect my ccing tools and technique until after head work had been done), and guessed-at piston dish ccs, I calculated stock Explorer 302 compression ratios no higher than 8.3:1 (SCR)/6.6:1 (DCR).
What's so confusing is why Ford setup the engines with this low of a compression and such a wide quench. They certainly left a lot on the table to be picked up by doing some work to these engines. I'm just itchin' it see what the difference between my stock Explorer 302 and a freshly assembled GT40p based 331 with Teflon side-coated pistons, tight quench, higher compression, ported intake, ported heads, 3 angle valve job, 1.6RRs, double-roller timing chain, and hi-torque cam, will be. Obviously the power will be better. That'd be a given without much effort. But what I'm most interested in is will the fuel economy be improved? All the research and engine builders I've talked to say it should. But no one can quantify how much is a reasonably expected improvement since very few have actually built a 331 with fuel economy in mind. It seems every 331 & 347 on the planet was build with only performance goals making it difficult to get any info about what to expect from a low RPM high torque 331 build.
Anyway, I pay for the kit tomorrow when I take the flywheel and balancer to them for doing the crank balance. So hopefully I'll have all the parts to start assembling it all by next week.
In stock form, the engine I'm doing all the work to had the pistons in the holes .015-.017" and the stock gaskets were .047" thick (same as the OEM replacements from AutoZone). Between those two, that's OVER .060" quench. Anything .060" or higher yields NO benefits at deterring detonation. You have to be at or below .050" to begin to benefit from quench. Most people aim for around .040" quench and ideal quench is .035" on most engines. Some engine builders have gotten positive results on older cast heads that were particularly known for their low RPM detonation tendencies with quench in the .025-.030" range. I'm aiming for quench in the .030-.035" range.
I had to guess at the stock piston's dish ccs to get stock compression ratios. I'm guesstimating the pistons were in the 9cc range. Aftermarket Keith Black flat top dual-lash pistons are 11.5cc so I estimated the stock pistons lower because aftermarket pistons generally have larger diameter lashes cut a little deeper to satisfy larger diameter aftermarket valves and higher lift cams. With the stock Explorer cam, stock gasket, measured piston compression heights, guessed-at stock head chamber ccs (I didn't perfect my ccing tools and technique until after head work had been done), and guessed-at piston dish ccs, I calculated stock Explorer 302 compression ratios no higher than 8.3:1 (SCR)/6.6:1 (DCR).
What's so confusing is why Ford setup the engines with this low of a compression and such a wide quench. They certainly left a lot on the table to be picked up by doing some work to these engines. I'm just itchin' it see what the difference between my stock Explorer 302 and a freshly assembled GT40p based 331 with Teflon side-coated pistons, tight quench, higher compression, ported intake, ported heads, 3 angle valve job, 1.6RRs, double-roller timing chain, and hi-torque cam, will be. Obviously the power will be better. That'd be a given without much effort. But what I'm most interested in is will the fuel economy be improved? All the research and engine builders I've talked to say it should. But no one can quantify how much is a reasonably expected improvement since very few have actually built a 331 with fuel economy in mind. It seems every 331 & 347 on the planet was build with only performance goals making it difficult to get any info about what to expect from a low RPM high torque 331 build.
Anyway, I pay for the kit tomorrow when I take the flywheel and balancer to them for doing the crank balance. So hopefully I'll have all the parts to start assembling it all by next week.
...Always Somethin'
89 Ranger Supercab, 331, ported GT40p heads w/1.6RRs, Crane Powermax 2020 cam, ported Explorer lower, FMS Explorer (GT40p) headers, aftermarket T5 'Z-Spec', 8.8" rear w/3.27s, Powertrax Locker, A9L w/Moates QuarterHorse, Innovate LC-1, James Duff traction bars, iDelta DC Fan controller
Admin of EECtuning.org
89 Ranger Supercab, 331, ported GT40p heads w/1.6RRs, Crane Powermax 2020 cam, ported Explorer lower, FMS Explorer (GT40p) headers, aftermarket T5 'Z-Spec', 8.8" rear w/3.27s, Powertrax Locker, A9L w/Moates QuarterHorse, Innovate LC-1, James Duff traction bars, iDelta DC Fan controller
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- MalcolmV8
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Re: CCing heads, my experience so far...
Chris, I'd have to say you made a mistake somewhere if you got 8.3:1 SCR for a stock Explorer engine. Even my supercharged Cobra didn't come with that low a compression from the factory. Someone should have factory specs somewhere, or maybe we can google it. I know my 95 Mustang GT which was a 302 had 9.5:1 stock compression. I'd imagine other 302s Ford produced would be in a similar range.
92 302 Ranger - sold
94 302 Ranger AWD - sold
07 BMW 335xi - tuned, boost turned up, E85 - sold
04 911 TT - to many mods to list. Over 600 All Wheel HP on pump gas - sold
2015 Coyote - daily driver
03 Cobra - 2.3 TVS on a built 12:1 CR motor with ported heads, cams, long tubes etc.
MD Racing Lean Protection Module
E85
Tuned by MD Racing
https://www.youtube.com/c/MalcolmV8
94 302 Ranger AWD - sold
07 BMW 335xi - tuned, boost turned up, E85 - sold
04 911 TT - to many mods to list. Over 600 All Wheel HP on pump gas - sold
2015 Coyote - daily driver
03 Cobra - 2.3 TVS on a built 12:1 CR motor with ported heads, cams, long tubes etc.
MD Racing Lean Protection Module
E85
Tuned by MD Racing
https://www.youtube.com/c/MalcolmV8
- cgrey8
- Supporting Member
- Posts: 4055
- Joined: Fri Dec 10, 2004 8:23 pm
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Re: CCing heads, my experience so far...
If I use the GT40p chamber spec which says the engine should have 58cc chambers, then the SCR goes up to about 9:1. However as measured, I got way above that. At smallest, they were 60cc. My estimate numbers were 61cc. But there's no way they were actually 58cc in stock form particularly now that I'm measuring them in the 60.5-61.5cc range AFTER having them decked down which takes CCs away from the chamber. But in all fairness, the valve job also does grind on the seats which pushes the valves ever-so-slightly into the head which adds ccs. And they also blended the seat which took some metal off too. But it wasn't exactly a lot. From the very beginning, I was confused why my GT40p heads were so high above spec.
But I guess it's possible there is an error somewhere. I've listed out all the data I know that goes into calculating SCR. If you find where I goofed, let me know. I'd sure like to find that out.
But I guess it's possible there is an error somewhere. I've listed out all the data I know that goes into calculating SCR. If you find where I goofed, let me know. I'd sure like to find that out.
...Always Somethin'
89 Ranger Supercab, 331, ported GT40p heads w/1.6RRs, Crane Powermax 2020 cam, ported Explorer lower, FMS Explorer (GT40p) headers, aftermarket T5 'Z-Spec', 8.8" rear w/3.27s, Powertrax Locker, A9L w/Moates QuarterHorse, Innovate LC-1, James Duff traction bars, iDelta DC Fan controller
Admin of EECtuning.org
89 Ranger Supercab, 331, ported GT40p heads w/1.6RRs, Crane Powermax 2020 cam, ported Explorer lower, FMS Explorer (GT40p) headers, aftermarket T5 'Z-Spec', 8.8" rear w/3.27s, Powertrax Locker, A9L w/Moates QuarterHorse, Innovate LC-1, James Duff traction bars, iDelta DC Fan controller
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- cgrey8
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Re: CCing heads, my experience so far...
Just recalculating assuming 58cc for the stock Explorer engine, here's what I got:
The .047" gasket is as I measured it coming off the engine as well as measuring the fire ring of a new FelPro OEM replacement (PN 8548PT-2) at AutoZone. Both were within .001" of each other and the FelPro website says those gaskets have a crush thickness of .047" which is what I measured. I can't remember what the ring diameter was, but most SBF gaskets are 4.100" diameter. Only a very few high performance gaskets are smaller with the smallest that I found being 4.060". Here's the SummitRacing website where I got the advertised crush thickness from:
Summit Racing FelPro 8548PT-2
The piston compression height is as I measured them on my engine. I sampled 5-6 cylinders all measuring in the .015-.017" depth in the holes. This is subject to change from engine to engine as engineering tolerances change and with wear. With block deck heights that are closer to the 8.200" spec and no wear in the connecting rod bearings & wrist pins, it is possible that other Explorer 302s locate the pistons higher than I measured.
Engine and Cam specs were entered using the following info:
Duration: 256°/266°@.006" lift
Intake Lobe Center: 118°
LSA: 115°
Crank Stroke: 3.000"
Connecting Rod Length: 5.090"
You can use any of the DCR calcs on Google. If anybody wants mine, I can email it to you.
As stated above, GT40p heads are spec'd to be 58cc. But mine were not near that. Even with my syringes measuring slightly larger than actual ccs, I was measuring in the 61-62cc range. The inaccuracy of my syringes is in the 1-2cc range, not the 4cc range as would be required for my chambers to have been 58cc in stock form. And after talking to others on the EECTuning.org site, they say it isn't uncommon for combustion chambers to be larger than spec'd by Ford. Why, I have no clue. But again, different Explorer engines could easily have different combustion chamber sizes. As I compare each of my heads, there are significant differences as detailed in my pictures on the EECTuning.org thread. So I concede that it is quite possible that other Explorer engines did have heads closer to spec...mine just weren't at least not by my measurements. The .047" gasket is as I measured it coming off the engine as well as measuring the fire ring of a new FelPro OEM replacement (PN 8548PT-2) at AutoZone. Both were within .001" of each other and the FelPro website says those gaskets have a crush thickness of .047" which is what I measured. I can't remember what the ring diameter was, but most SBF gaskets are 4.100" diameter. Only a very few high performance gaskets are smaller with the smallest that I found being 4.060". Here's the SummitRacing website where I got the advertised crush thickness from:
Summit Racing FelPro 8548PT-2
The piston compression height is as I measured them on my engine. I sampled 5-6 cylinders all measuring in the .015-.017" depth in the holes. This is subject to change from engine to engine as engineering tolerances change and with wear. With block deck heights that are closer to the 8.200" spec and no wear in the connecting rod bearings & wrist pins, it is possible that other Explorer 302s locate the pistons higher than I measured.
Engine and Cam specs were entered using the following info:
Duration: 256°/266°@.006" lift
Intake Lobe Center: 118°
LSA: 115°
Crank Stroke: 3.000"
Connecting Rod Length: 5.090"
You can use any of the DCR calcs on Google. If anybody wants mine, I can email it to you.
...Always Somethin'
89 Ranger Supercab, 331, ported GT40p heads w/1.6RRs, Crane Powermax 2020 cam, ported Explorer lower, FMS Explorer (GT40p) headers, aftermarket T5 'Z-Spec', 8.8" rear w/3.27s, Powertrax Locker, A9L w/Moates QuarterHorse, Innovate LC-1, James Duff traction bars, iDelta DC Fan controller
Admin of EECtuning.org
89 Ranger Supercab, 331, ported GT40p heads w/1.6RRs, Crane Powermax 2020 cam, ported Explorer lower, FMS Explorer (GT40p) headers, aftermarket T5 'Z-Spec', 8.8" rear w/3.27s, Powertrax Locker, A9L w/Moates QuarterHorse, Innovate LC-1, James Duff traction bars, iDelta DC Fan controller
Admin of EECtuning.org
- Dave
- Supporting Member
- Posts: 1524
- Joined: Fri Dec 10, 2004 4:36 pm
- SM: No
- Location: Central Wisconsin
Re: CCing heads, my experience so far...
Chris, looking around and getting all kinds of different numbers for the cc. The FRPP catalog lists the "P" heads as a 60cc nominal. Same page shows the GT-40's to be 65.5. The '97' Explorer shop manual shows 63.4-66.4 cc. Thsi good comparison chart show the stock "P" heads at 58cc. Think the only real way of getting a consistant vol is get some CNC machined heads. Doing a sand casting is just not that accurate over all. Now investment castings are in a whole different world. I'm like Malcom, my nominal CR got changed to 8.6 when I went to the forged bottom end.
On another note, I'm sure you have run the numbers on that 331 as to what HP/Torque you are expecting. Were/are you able to run the numbers down to low RPM's? Got a reason for asking.
http://www.carbdford.com/tech/flowdata.htm
Dave - calling for possible rain-snow this weekend, at least the tornados missed right here.
On another note, I'm sure you have run the numbers on that 331 as to what HP/Torque you are expecting. Were/are you able to run the numbers down to low RPM's? Got a reason for asking.
http://www.carbdford.com/tech/flowdata.htm
Dave - calling for possible rain-snow this weekend, at least the tornados missed right here.
'66'Ranchero 302/5 speed
2015 Stage 3 Roush - rated at 670 hp
2000 Ext Cab/4 door swap project
2000 Ext Cab/4 door, Summer beater
2000 Ext Cab/4 door, Winter beater
1969 Fairlane Cobra in Barn, just waiting
2015 Stage 3 Roush - rated at 670 hp
2000 Ext Cab/4 door swap project
2000 Ext Cab/4 door, Summer beater
2000 Ext Cab/4 door, Winter beater
1969 Fairlane Cobra in Barn, just waiting
- MalcolmV8
- Supporting Member
- Posts: 2597
- Joined: Fri Dec 10, 2004 4:50 pm
- SM: Yes
- Location: Kansas City, MO
Re: CCing heads, my experience so far...
Dave, your 8.6 is still higher and in a nice area. Mine is 8.1:1, well 8.15:1 to be exact. It's way to low but I didn't know at the time. It was one of those deals where I hadn't thought about it a lot because I wanted to stick with stock 8.5:1 but then the machine shop calls me up asking all sorts of questions and has issues with getting over sized aftermarket pistons with stock dish and wanted to change it. I called around to a few performance shops and they all said lower the compression. The lower the better. In fact MMR told me specifically to use the 19 cc dished pistons and spoke very highly of them. They are a huge reputable place so I went with it.
Having done that I'm sorry I did. Throttle response blows compare to stock. Over time I got used it and it's just normal now but I know when I first got it running I could tell a big difference. Also when comparing numbers on the forums the guys with a bit more compression are making more power. Sure boost goes down as compression goes up but time and time again the guys with 9.1:1 compression are making more power on less boost than the 8.5:1 guys running more boost. 9.1:1 also has fantastic throttle response. Oh well end rant lol.
Back to head CC'ing.
Having done that I'm sorry I did. Throttle response blows compare to stock. Over time I got used it and it's just normal now but I know when I first got it running I could tell a big difference. Also when comparing numbers on the forums the guys with a bit more compression are making more power. Sure boost goes down as compression goes up but time and time again the guys with 9.1:1 compression are making more power on less boost than the 8.5:1 guys running more boost. 9.1:1 also has fantastic throttle response. Oh well end rant lol.
Back to head CC'ing.
92 302 Ranger - sold
94 302 Ranger AWD - sold
07 BMW 335xi - tuned, boost turned up, E85 - sold
04 911 TT - to many mods to list. Over 600 All Wheel HP on pump gas - sold
2015 Coyote - daily driver
03 Cobra - 2.3 TVS on a built 12:1 CR motor with ported heads, cams, long tubes etc.
MD Racing Lean Protection Module
E85
Tuned by MD Racing
https://www.youtube.com/c/MalcolmV8
94 302 Ranger AWD - sold
07 BMW 335xi - tuned, boost turned up, E85 - sold
04 911 TT - to many mods to list. Over 600 All Wheel HP on pump gas - sold
2015 Coyote - daily driver
03 Cobra - 2.3 TVS on a built 12:1 CR motor with ported heads, cams, long tubes etc.
MD Racing Lean Protection Module
E85
Tuned by MD Racing
https://www.youtube.com/c/MalcolmV8
- cgrey8
- Supporting Member
- Posts: 4055
- Joined: Fri Dec 10, 2004 8:23 pm
- SM: No
- Location: Acworth, Ga (Metro Atlanta)
- Contact:
Re: CCing heads, my experience so far...
After doing this build, I tend to agree. And to get the CCs of each chamber closer to target, I'll be using a dremel-bit to grind the chambers to be the same cc down as close as I can measure or have patience for. They are in the 60.6-61.3cc range right now. I need them to all be in the ~62.0cc range to keep the Dynamic Compression Ratio safe/tolerable for a 192°F Tstat and pump gas. The shaving will also have the added benefit of unshrouding the intake valves, something flow benches have shown really helps with GT40p heads. Oddly unshrouding the exhaust valves has little to no effect on flow.Dave wrote:...Think the only real way of getting a consistent vol is get some CNC machined heads. Doing a sand casting is just not that accurate over all...
If I drop down to a 180°Tstat, I could tolerate a higher DCR. But for Hotlanta summers, I'm not wanting to push that limit. I may have to install the 180°Stat as it is.
Here's a DCR/Octane/Temp chart I found interesting:
![Image](http://image.popularhotrodding.com/f/8610173+w750+st0/0311phr_compress_07_z.jpg)
People on other forums say this chart is a bit conservative and will keep you safe. But its limits can be pushed a tad. But if the chart is the limit, you can see that I would require a 180°Tstat with 93 octane running a DCR of 8.2-8.3.
I don't have a desktop dyno program. You ran the numbers for me years ago and I still have those runs. But I don't have anything other than those. I could post it, but the forum file size limits won't let me even zipped. Unzipped, the forum won't allow *.pdf files. Although looking at it, I realize the cam specs were entered into the program wrong. The exhaust lobe values were off so if you still have that program installed and ready to use, contact me via email and I'll indicate what it is that was entered wrong. We can also re-run for the compression I'm actually looking to run and see how the simulation looks with more accurate/known info.Dave wrote:...On another note, I'm sure you have run the numbers on that 331 as to what HP/Torque you are expecting. Were/are you able to run the numbers down to low RPM's? Got a reason for asking...
...Always Somethin'
89 Ranger Supercab, 331, ported GT40p heads w/1.6RRs, Crane Powermax 2020 cam, ported Explorer lower, FMS Explorer (GT40p) headers, aftermarket T5 'Z-Spec', 8.8" rear w/3.27s, Powertrax Locker, A9L w/Moates QuarterHorse, Innovate LC-1, James Duff traction bars, iDelta DC Fan controller
Admin of EECtuning.org
89 Ranger Supercab, 331, ported GT40p heads w/1.6RRs, Crane Powermax 2020 cam, ported Explorer lower, FMS Explorer (GT40p) headers, aftermarket T5 'Z-Spec', 8.8" rear w/3.27s, Powertrax Locker, A9L w/Moates QuarterHorse, Innovate LC-1, James Duff traction bars, iDelta DC Fan controller
Admin of EECtuning.org
- Dave
- Supporting Member
- Posts: 1524
- Joined: Fri Dec 10, 2004 4:36 pm
- SM: No
- Location: Central Wisconsin
Re: CCing heads, my experience so far...
Well do Chris! Beautiful here today as opposed to the weekend. Got to get the oil changed on Stang, battery charged on lawn mower and a couple of other things. Big house, big lawn and too many projects.
Dave
Dave
'66'Ranchero 302/5 speed
2015 Stage 3 Roush - rated at 670 hp
2000 Ext Cab/4 door swap project
2000 Ext Cab/4 door, Summer beater
2000 Ext Cab/4 door, Winter beater
1969 Fairlane Cobra in Barn, just waiting
2015 Stage 3 Roush - rated at 670 hp
2000 Ext Cab/4 door swap project
2000 Ext Cab/4 door, Summer beater
2000 Ext Cab/4 door, Winter beater
1969 Fairlane Cobra in Barn, just waiting
- MalcolmV8
- Supporting Member
- Posts: 2597
- Joined: Fri Dec 10, 2004 4:50 pm
- SM: Yes
- Location: Kansas City, MO
Re: CCing heads, my experience so far...
Chris, could you explain the t-stat a bit more. You said you were going to be running a 192 but could tolerate more DCR on a 180 but not wanting to drop to a 180 with hot summers. Wouldn't a lower t-stat be desirable in super hot summers? I know I run a 170 in the Cobra in the summer.
92 302 Ranger - sold
94 302 Ranger AWD - sold
07 BMW 335xi - tuned, boost turned up, E85 - sold
04 911 TT - to many mods to list. Over 600 All Wheel HP on pump gas - sold
2015 Coyote - daily driver
03 Cobra - 2.3 TVS on a built 12:1 CR motor with ported heads, cams, long tubes etc.
MD Racing Lean Protection Module
E85
Tuned by MD Racing
https://www.youtube.com/c/MalcolmV8
94 302 Ranger AWD - sold
07 BMW 335xi - tuned, boost turned up, E85 - sold
04 911 TT - to many mods to list. Over 600 All Wheel HP on pump gas - sold
2015 Coyote - daily driver
03 Cobra - 2.3 TVS on a built 12:1 CR motor with ported heads, cams, long tubes etc.
MD Racing Lean Protection Module
E85
Tuned by MD Racing
https://www.youtube.com/c/MalcolmV8
- MalcolmV8
- Supporting Member
- Posts: 2597
- Joined: Fri Dec 10, 2004 4:50 pm
- SM: Yes
- Location: Kansas City, MO
Re: CCing heads, my experience so far...
Dave, I hear you on the yard stuff. Watering, putting down grass seed etc. myself. Sharpened up the mower blade, new plug, filter, oil and ready for summer!
92 302 Ranger - sold
94 302 Ranger AWD - sold
07 BMW 335xi - tuned, boost turned up, E85 - sold
04 911 TT - to many mods to list. Over 600 All Wheel HP on pump gas - sold
2015 Coyote - daily driver
03 Cobra - 2.3 TVS on a built 12:1 CR motor with ported heads, cams, long tubes etc.
MD Racing Lean Protection Module
E85
Tuned by MD Racing
https://www.youtube.com/c/MalcolmV8
94 302 Ranger AWD - sold
07 BMW 335xi - tuned, boost turned up, E85 - sold
04 911 TT - to many mods to list. Over 600 All Wheel HP on pump gas - sold
2015 Coyote - daily driver
03 Cobra - 2.3 TVS on a built 12:1 CR motor with ported heads, cams, long tubes etc.
MD Racing Lean Protection Module
E85
Tuned by MD Racing
https://www.youtube.com/c/MalcolmV8