new 671 blower

MalcolmV8 · Post by **MalcolmV8** » Tue Dec 23, 2008 3:28 pm

I don't have any first hand experience with the 671 blowers. My dad had one on a 350 chevy small block many many years ago but I don't remember much of anything about it.

The 03 Cobras with either Eatons, whipples, or kenne bells is all I'm really familiar with. They have quite a few 25 PSI Cobras running on the factory 8.5:1 compression but running higher octane gas. Those that rebuild their motors seem to opt for 9.1:1 compression ratio. I'm not sure where that number came from but it's definitely caught on with the crowd and that's what they seem to use.

Myself I'm running a ported eaton with a 2.76 pulley which puts me around 14 PSI.

To the original poster, I have no idea what hp you'll be making but 10.2:1 with 9lbs of boost should be one heck of a ride.

Dave · Post by **Dave** » Tue Dec 23, 2008 3:40 pm

Well know nothing about the 671 either. I'm running 9.8 to 1 with only 5 lbs of boost, internals just arn't that strong for much more like what Malcom has. Truck sure looks good, want to trade your weather right now? Got a spare room to rent for the Winter?
Dave

cgrey8 · Post by **cgrey8** » Tue Dec 23, 2008 3:58 pm

Anything's possible once you accept that the engine should only be WOTed with racing gas, propane, meth, or E85. All the limitations I'm referring to are ones where people are forced to running pump gas.

Although I do have to admit, a track-only vehicle where the builder has chosen to run a low compression engine, I would expect to be running racing gas. In which case, I wouldn't be surprised if the engine could handle 30+PSI. But I have no clue if such an engine would be a 4.6L/5.4L mod. I would expect such an engine to be an aftermarket block that's stronger than stock blocks.

As for people upping the compression to 9:1, that would make sense as long as they are not upping the compression AND upping the boost beyond 15PSI. Higher compression engines make better engines in my opinion...it just limits the boost headroom. But I too am curious as to what the attraction to upping the compression for others is. If you ever talk to someone that does that, find out what boost and fuel they are running with the upped compression.

rojam18801 · Post by **rojam18801** » Tue Dec 23, 2008 4:54 pm

ok here's a few picture's of blower install.....not done.

87ranger · Post by **87ranger** » Tue Dec 23, 2008 5:08 pm

sounds like fun, i have a little experience with boost and sbf's

rojam18801 · Post by **rojam18801** » Tue Dec 23, 2008 5:13 pm

thanks guys for all the info. the block i have is a sportsman block been told it will handle 900 hp. i should be pushing 800 hp without the nos and i dont plan to turn that on. the bottle is even full. to anyone who would like to do this there is no room for radiator and i have 1/8 inch between the 671 and firewall passenger side driver side about 3/4 inch.

rojam18801 · Post by **rojam18801** » Tue Dec 23, 2008 5:20 pm

87 ranger what compresion do you run and how much boost.carb or fuel injection. how does it idle. i have lots of questions. been told with blower it will surge at idle.

MalcolmV8 · Post by **MalcolmV8** » Tue Dec 23, 2008 5:27 pm

rojam18801 wrote:been told with blower it will surge at idle.

Is that because of carbs? my cobra idles smooth as can be. The Eaton blower has a boost bypass though, when boost is not required it recirculates within itself. Does the 671 do the same thing or is it constantly pushing boost into the motor? maybe that's why you'd get an idle surge?

rojam18801 · Post by **rojam18801** » Tue Dec 23, 2008 5:47 pm

malcom v8...... no bypass on 671 blows all the time. don't know why they surge. a guy i know has a ratrod here in florida with 350 chevy and 671 his surge's big time. he said he had 13 to 1 comp but i dont know if that's with blower or before blower. i'll try to find him this friday. i met him at local car show's

v8ranger · Post by **v8ranger** » Wed Dec 24, 2008 3:36 am

SWEET!!!!!! I would give my left nut for a setup like that, hell maybe even both nuts, lol.

rojam18801 · Post by **rojam18801** » Wed Dec 24, 2008 6:10 am

thanks v8 ranger, coments like that are the reason i love this little truck. i never thought i would have anything like this. when i work on it i spend most my time sitting staring at it. dam i can't belive it's mine. my wife says all it's good for is shaking the windows. so that's what i named it [window shaker]. driving it before the blower was a rush, it don't like to idle, shakes all over. when i start it it comes to life like a panther snarling. a women at a show almost fell on her butt when it started. scared the hell out of her. trying to leave at a red light is a real trick, just a hair of throttle and the tires break louse. cops stare at it but never been pulled over yet. i'll tell you i'm 62 years old and this thing is a handful to drive. damm i love it......the old trucker

87ranger · Post by **87ranger** » Wed Dec 24, 2008 7:20 am

i run 9-1 and ive had it up to 12 lbs on occasion but i mostly drive around at 7lbs cause i can blow the tires off at 70mph, that surge is strickly a tunning or lack of tunning issue, with fuel injection the map sensor and o2 can modify the fuel map to deal with the lean surge, butt on a carb blower setup that surge is and idle/airbleed isssue that can be fixed with lots of patience, bds makes a nice efi setup that bolts on the top of the blower that would be nice for drive ability, kuhl superchargers makes and efi lower manifold that the blower bolts onto that allows tuned port injection and the use of a bypass valve to avoid overheating the air charge in the blower case, but like o said earlier, that surge is a lean issue that isnt dealt with properly, with everything set up right it will idle and drive like stock

87ranger · Post by **87ranger** » Wed Dec 24, 2008 9:56 am

looking at you engine configuration ide "guess" that your making 425-475 on just engine and without knowing exact boost and iat's i cant guess hp,i would use a wide band o2 to do the tunning on your carbs, shoot for 13.4-13.6 at idle, 14.0-14.5 at cruise and 11.5-12.5 at wot, and i wouldnt run anything over 5lbs on pump gas with the compression and the inefficiency of the blower,or youll be picking up chunks of block and engine.

i recently tunned my buddys 95 stang on a mustang dyno with default altitude and temp compensations in the program, his engine was a dart 331 with afr's big hyd roller victor jr efi and a s- strim super charger, through a five speed and 55lb injectors we made 405 at the tires with 15lbs of boost and the injectors were tapped

the same day we did my truck, a stock block 347 with procomp heads, big hyd roller and a parker funnelweb intake with 120lb injectors and 7lbs of boost from two 61mm t4 turbos with .84 turbines through my sluchbox aod i made 403 at the tires.

i made nearly as much hp and way more tq than he did with half the boost, efficiency is the key

Dave · Post by **Dave** » Wed Dec 24, 2008 1:04 pm

Nice Pictures! With that cover on the truck, I could picture a Willys from 40 years ago. I've been scanning in some pictures from the late 60's from the Bryon dragstrip, that what brought it to mind.
Good luck, have fun, sounds like you are.
Dave

prpleranger · Post by **prpleranger** » Wed Dec 24, 2008 4:12 pm

rojam18801 wrote:. its like having a birthday present and can't open it up.

i know the feeling i had mine on the road for about 6 months before the tranny blew now its been over a year gettin it all back together granted if i was rich it would have been alot shorter but i have jumped through hoops with my aftermarket crank not fitting right... anyone else had that problem with a 302... counterweight on crank hits bottom of piston, i even looked up all my part numbers to make sure they matched they did, damn eagle!!! lol