V8-Ranger.com

How much boost can I safely do on the stock internals of my 1990 5.0L in my
Ranger?? Do you think it will handle 12 to 14psi without being a bomb??

No I do not....hope that wasn't to blunt.....

the most boost i would run an a STOCK 5.0 is NO more then 9psi ... ppl run 9psi ll the time..... then ALOT more only run 6 psi.... if you go over 10psi .. you need all new internal parts that can handle all the added pressure on the parts....... mostly all Forged stuff. ... but personally i wouldnt go over 9psi .... i had a supercharged 5.0 one time not so long ago in the past..... it had an 6psi pulley ... ans that was PLENTY of that ALL stock 5.0 ....lol

hope this works for ya ......

The biggest limiting factor is the pistons and connecting rods. I've heard 5.0L Mustang GTs did come factory with forged pistons up until about 94...other 5.0Ls (HO or non-HO) did not. What I don't know is whether that means anything. They were still stock equipment.

The other weak link is the stock connecting rods. Even if you pulled spark to eliminate detonation, over-enriched to control combustion temps, and held back the boost levels, you still have the worry of just how long you can stress weak stock connecting rods. It's even worse that damage to them is cumulative. So they may hold together for 10 runs, but the 11th may be the one that they grenade on you. Up to about 400-450hp, aftermarket I-beam connecting rods work fine. However once you go over that, you really should be considering H-beams. I've always believed that ANY boost should get H-beams just to be on the safe side. And if the engine will be spinning high RPMs, H-beams for sure. The stress of high RPMs is often greater than the stress from the combustion when things are slinging around at 7000+.

And as for the crank, the issue isn't strength. Stock and aftermarket nodular iron works fine up to 600hp which is about the limit of the block in the 1st place. Cast steel is the normal upgrade. And of course, forged steel cranks are the upgrade from there. So if nodular iron is good for block-splitting HP, why do the "upgrade" cranks exist? It's not HP production that you have to consider these upgrades for. It's when you plan to make that HP at high RPMs that you begin to consider what crank you want. The vibration and harmonics due to high RPMs start to play hell on the main bearings so to rid the vibration, you internally balance. Cheap cranks are notorious for being extremely difficult to get balanced for stock externally balanced setups. They can be nearly impossible to setup for internal balancing. Whatever you save on a cheap crank, you are guaranteed to loose in the machine shop getting it balanced. IMO, you really want to buy your crank from the machine shop that will be doing the balancing so you can be sure they will choose the crank that they know will balance easily. BTW, internally balancing means either new or modified flywheel/flexplate and balancer.

Other weak links in stock engines are the stock valve springs/retainers. They aren't designed for high RPMs. The springs are weak and the retainers are heavy...both of which make low-noise, stable, & durable daily driver engines, but also make for lousy performance over 5500RPMs as the valves begin to float. Reuse those stock valve train components on an upgrade cam with faster ramp rates and/or higher lift, and the valves will float even quicker.

But this is way off topic from the original question of what a stock block will tolerate as it relates to boost.

High RPM's will never be the problem.. I don't go over 5000... Thank you all for the info... Couldn't cancel the bid and didn't get out bid, so I guess I own the smaller pulley anyway....

Chris,
you are correct on the HP ratings on the pistons - rods - and crank ..... but there is another factor that can fail in the 450 to 500 hp range ...... i know cuz i did it ..... the stock 5.0 block in FACTORY condition ... with NO MODS to it at all........... will only hold 450-500 hp ...... per Ford's specs ....... or ya run a high risk of cracking the block .... or like i did,,,,,, split it in half !!!!!!!

The typical stock Windsor block should be capable of producing about 600hp...and tend to split down the center somewhere around 650. Although that 600hp capacity is with caveats...as you point out.

If you hit 500hp and the block split, there was probably something that caused it. The most likely culprit is an externally balanced rotating assembly that hit a resonant RPM. Harmonics and resonant frequency vibrations are a REAL concern when the RPMs get up there. Even internally balanced rotating assemblies will have harmonics that can be damaging, but the hope/intention is that the severity of the harmonic will be tolerable. Some race engines are often built where the builder knows about a resonance that is being built into the engine, but he doesn't care because the operating RPM is higher than the resonant RPM. Since you have to spend time at a resonant RPM before it builds to destructive levels, blowing through the resonant RPM is benign. Keep in mind, when I say spend time, I mean milliseconds holding at or near the resonant RPM.

Another possibility was that the engine had too much advance. Even if you didn't hear ping, it might have had more advance than could be tolerated OR things were so loud, the detonation wasn't heard. Controlling spark on an EFI system is pretty straight forward. You just type in the advance you want at the given RPM/Loads you are tuning for. I don't know if non-computer controlled distributors can be as easily configured since I've never dealt with one.

Then again, you might have just had a weak block with a flaw from the factory that couldn't tolerate what you were doing. Who knows...

It's also quite possible that different era of Windsor blocks have different capabilities. For example, when I had my 97 Explorer block in the machine shop, the machinist noted how it didn't cut as nicely as other Windsors he's done. As it turned out, he actually over-cut the block and had to abandon it. In replacement, he gave me an 89 era GT 5.0L block he had laying around the shop. And he noted how it cut much more like what he expected. If there's anything to what he's saying that would suggest that Ford changed the cast iron formula for the Explorer Windsor blocks. After all, it was the ONLY vehicle using the 302 Windsor from 96-01. Since the Explorer is not a performance application, I could easily see how they might have decided to save a few bucks by cheapening the block cost. Thus, it would not surprise me if someone figured out that Explorer blocks crack much sooner than GT era Windsor blocks do.

v8ranger wrote:How much boost can I safely do on the stock internals of my 1990 5.0L in my
Ranger?? Do you think it will handle 12 to 14psi without being a bomb??

It will handle 1psi below is failure point. That failure point is truly hard to say. I've seen stock 302s running all day on 15psi boost using water/meth injection. Also seen stock 302s running 6psi that come apart. There are tons on other factors involved. Tuning is absolutely critical on boosted engines. Your pistons will be the determining factor. Stock cast pistons don't like excessive heat. Add an injection kit or intercooler to lower intake charge temps and keep timing safe. Just remember- there are no guarantees when building horsepower.

the guy said he was getting about 14 pounds of boost. I dont know what his setup is. i am getting about 6psi at 4500rpm's on the 4" pully. this one is 3 1/4. Dont know if I will be getting the same boost as he was or not..? Dont know if he was running EFI or carb and how much that makes a differance. Im sure heads make a differance also in how much boost it makes..?

Just looked thru three different Mustang sites any seems like 450 hp safe, 500+ getting iffy and 600 hp not for long. Saw some great examples of them splitting right down the middle. Boost was about 8-9 as the limit, some turbo sites went a bit higher,
Dave

Turbos generally do produce more flywheel HP because there's less parasitic load with turbos so more of the actual HP being made goes out the flywheel.

Well the pulley didn't end up fitting my supercharger.. Guess the Novi and SN 92 are not the same pulleys.. Maybe that's a sign not to get that small of a pulley...

Stock 302 and 4.6 guys generally don't go over 450 whp on stock internals which is in the ball park of 6 PSI generally. Even 8 to 9 is really pushing it. I've had a few buddies push 500 whp on their stock internal Mach's and such and they always end up blowing them up. 14 PSI on stock internals won't last very long at all.

Just as a side note of fun here's what my car is pushing right now. Obviously has forged rods and pistons

safe i would say 5-6 psi any more than that i think you are pushing blocks limits.

Went to a 3 1/2 inch pulley. So far so good.. Boost comes in much sooner now. Getting 5psi at 3500rpm's. Not sure what the max is yet, fuel pump wont keep up with this pulley once It gets up around 4500 rpm's, built in governor I guess, lol.... Maybe that's not a bad thing.. Haven't found a pump yet, but really haven't been looking much, Been working on the boat and putting to much money in that this year. Dam thing is going to coast me $700 before I even get it in the water.. Sure is going to make fish pretty expensive per pound this year.. Coast me $500 last year... Guess that's not bad considering its an 84 with a 71 motor and outdrive. I haven't had to put one penny into it in 10 years so I guess its time..