I have finally decided to build a 383 stroker motor and match it with a weiand supercharger, but i have a few questions maybe some people on here will know.

I am trying to acheive is 600+ horsepower, pump gas, and streetable/street legal.

I already have the block and bottom end put together, its a 383 with forged eagle internals running 8.75 compression. As for a power adder, i am looking for something that will allow me to stick a blower out the hood and still maintain my objectives i stated above. Does anyone have an idea if it would be wise to go with an 8-71 or a 6-71?

Im also looking for heads, my eyes are on AFR 220s, but if anyone has any ideas, let me know...

thanks for the thoughts

 

If you don't have the heads yet, you don't really know what your CR will be eh? (or is that calc'ed based on 76cc heads?)

I think 210cc is plenty. The big AFR heads, they don't flow as well. I mean, percentage wise, you suffer dimishing returns, you go up lets say 20% in port size, and gain 2% in CFM flow. I don't think it's worth it. 262cfm is flat out amazing at .500" lift anyway, going up 2 cfm isn't worth going up 10cc's in intake port size IMHO.

I think you've got a good solid build set up going on. I'm not sure on the blower, so I wanted to tag on to this thread to find out. Dual carbs and the triple stoplights poking out? (sexy).

 

Thats why im going for the scoop look, cause its mean.
I originally was going the twin turbo route but there is too much fabrication involved and its much more expensive (albeit more efficient) than the roots method.

By the way, its 9.2 at 58CC, 8.75 at 64CC and 7.9 at 76CC

The 210s were also what i was thinking of going with, and i'll probably settle with those.

 

AFR 210's will be enough to get you where you want.. hell, if you want, get the new AFR 210 eliminators.. not sure on blowers but a weiand 8-71 should do the trick.. also, dual 500 OR 650 holleys.. a blower cam wouldnt hurt either.. it will actually help ALOT compared to any other cam..

or you could go the better way and go procharger.. theres a guy on here that just cracked 800rwhp with a single carb.. but i feel you on the desire for something to stick out the hood..

 

Yep, im thinking dual 600cfm holleys

Im just not sure if the 8-71 is streetable enough or if its gonna be overkill for what im looking for. From what ive seen, 8-71 is meant for the track and 6-71 is meant more for the street, but if anyone has any experience with this, please let me know.

 

Please dont buy a Mr Gasket scoop.. it looks like crap. If you want a carb hat get one that "looks like" a Enderle hat.. it goes for about $400 but I forget who makes it.

I had a 383 w/a 6-71 on it.. The 6-71 is plenty but if you have the extra $ get a 8-71. I was running Dart Iron Eagle 215cc heads w/a hydraulic flat tappet cam from Comp (NitrousHP 284) and it ran great. I had dual 650 holley carbs but I think 750 or 850s would have worked better. A 6-71 is no more streetable then a 8-71. The 6-71 will work harder flowing the same amount of air a 8-71 will. Look into a water/methanol injection kit as the "super chiller" is pretty expensive.

 

Thanks, the 8-71 was what i budgeted for, but i cant seem to find one that is of satan finish. Anyone know of the cheapest place to pick up this supercharger?

I was just hoping that a 6-71 would suffice and save me some dough, but if its not worth it, then its pointless.

Thanks for the info

 

Yea, the 8-71 just doesn't have to work as hard to move the air, hence it'll keep it cooler etc etc.
I'd highly recommend the 76cc heads for the 7.9:1 CR. You can run more boost that way, which is a lot better for power than a CR increase. :thumbsup :

 

btw, I ran the 8mm pullies, had the power valves blocked off but I dont remember the jetting. You're going to love it..post pics of the buildup as you go along. Oh, and I also had my timing locked out.. again i forget but it was "all in" by 3000 rpm, using a MSD Pro-billet distributor.

here's the hat I'm talking about and I was off by a few bucks.. its $745 but it looks pretty damn good!

http://alsblowers.com/sc520.html

BDS also makes a nice hat ..

http://blowerdriveservice.com/catego...pany_id=101011

 

If you're only looking for 600HP then a 6-71 will be plenty.

Do you know the size difference between a 6-71 and an 8-71? It's not anything like you would expect. A 6-71 moves a theoretical volume of 411ci per revolution. An 8-71 moves 436ci per revolution. That's only a difference of SIX PERCENT between the two. That's not much, and certainly nothing like the 30% difference that most people expect it to be.

 

yea.. it says that on my website.. LOL.

but it also depends on whether his 6-71 is a small or large bore blower.. then you'll see the difference between the 6-71 and 8-71... almost 100ci more air flow.

 

Can you run the 8-71 off pump gas with the 7.9 compression?

All things being equal, whats the horsepower difference between the 6-71 and the 8-71 approx.?

 

yea you can run the 8-71 on pump gas.. since you're going to run a SBC find out how much ci the 6-71 flows.. if its 411 or so then its not worth spending the extra $ on a 8-71 like Damon said. 600 hp is a pretty easy to do w/a blower/sc.

 

there is someone on maui running a 355 with a 14-71 blower on pump.. that ***** is HUGE

 

Go with the 6-71 and you wont be dissapointed. 700 hp is easily attainable with them. No matter which SC you get, your gunna want a water/meth kit that run off boost reference, because your inlet charge will eventually heat up. That 8-71 is wayyy to big for a 600 hp application and will hurt your low end torque on the street. The 8-71 will leak boost at low rpms (street driving) as the engine is trying to get the rpms to spin those BIG Helix rotors on them untill the rotors are spinning fast enough to seal/over come it. Not saying anything bad at all about the 8-71, the 6-71 will leak boost too, but not for as long because of its smaller design. The 8-71 is just an all out Drag SC, not meant for street driving and the common lower RPMs seen while driving around the streets. Also the 8-71's boost range extends way out of your engines 6000 rpm band range. Youll be alot more happy with the 6-71 for its mid and upper RPM power and not killing off the Low end Torque you still have. Besides, the boost runs a little better in accordance with your 6,000 rpm Redline. Just my
[SIGPIC][/SIGPIC]

 

8-71 "wayyy to big for 600hp" ?? "Hurt low end torque" ? "8-71 is just an all out drag sc" ?

I take it you personally have tested this load of crap you're talkin about? Dont tell me you have a Mr Gasket scoop under that hood for the 'fake blower look' right?
lol.

You're completely misinformed, please take your back.

 

YES a 8-71 is all out drag. Its made to work for the guy that wants to be launching with a 4500 stall and running it to redline. And for your information, a Weiand 177 blower will provide MUCH more snappy Bottom End Torque down low for the streets than a 6-71 or 8-71. The 6-71 and Exspecially the 8-71 IS NOT MADE FOR LOW END TORQUE!!!! and the 8-71 is definatly not designed to be use as a street SC (not saying that it can't be worked to be used that way)

Nope, i havent driven a 8-71. I have a 6-71 that i put on my vega during track season, And yes, my camaro is a B&M Hood scoop, but I also have a weiand intake and 177 s/c for my camaro when i feel like wasting some gas at the strip mind you. I reccomened the 6-71 over the 8-71 to fawcett10 because 1) its the more streetable of the two in the fact of its intended rpm usage range, 2) its Lower in cost while providing the boost he's looking for, and 3) ease of obtaining 600 hp using it.
Im just helping this guy out, he asked a question, so i gave him my answer with my experience, but sorry, YOUR the one that is misinformed buddy, so stop throwing out replies like you did to me. It makes it appear that you have to get all aggressive to cover up the fact that you probably dont have a clue wtf your talking about except for what you read on the manufacture's web page. Ask anyone in this forum BDR, A 8-71 is engineered to power upper rpms, NOT aid in Bottom end torque or to be that efficent in the average rpm range you cruise around at on the streets. if you want that power and torque made for the streets, go with a smaller s/c.

 

Yea I read that Chevy High Performance article too. That 177 blower will be heating up the air alot more then the 8-71 will making the same amount of boost. The 8-71 will make more power, period. Down here in Texas there are quite a few 8-71 & 6-71 blower cars running around on the street. They sure dont complain about any "torque" issues and I havent heard any of them wanting to trade down to a 177. lol


you dont choose a roots blower based on RPM, you choose it based on engine size and what boost level you're intending to run. If he's planning on running that 383 that 6-71 would be adequate. My question was how much the 6-71 flowed.. if it was a small bore blower it flows considerably less then a 8-71. Being that it is a Weiand I'm sure it flows like Damon suggested in the 400ci range. Sorry man, you're still wrong.. real world texans run big blowers and low ET's..all on the street.. I moved on to the world of turbos..but have a soft spot for roots blowers.

 

Heres an update for you guys...

I got the car out of the shop finally, and had a racebuilt tranny installed. The guy does outstanding work and specializes in building bullet proof trannies. He gave me a 2 year 24k warrentee with 700 horsepower at the wheels.

Since i went all out on the tranny, i can boost power now up towards the 800 range. I still want to be driveable on the street and still tear up the track.

I have been talking to a local machine shop and i have pretty much got it narrowed down to a couple options.

Go with a procharger 1cx100-d1sc and possibly an intercooler or go with a weiand 6-71 or 8-71.

The heads are between trickflow and afr, but im still looking at which set would work the best with what supercharger.

Im still not sure which route to go, procharger seems to be the most logical and streetable, and i could run 825 horsepower (as procharger claims).
Weiand looks sexier and would be alot of fun and tear up the track, but drivability is in question, mostly cause i have never riden or worked on one before. If i go weiand, i still havent made up my mind on a 6-71 or 8-71 but the 8-71 has the edge.

Please share with me your input as i am dropping alot of money into this set up and i want to make sure it turns out to be what i am looking for.

 

a centrifugal is more efficient.

im pretty dumb when it comes to roots cars.... but the ones ive seen at the track have ZERO driveability. even for a drag car. they fire up, and vroooom.... vrooooom.... vroooomm.... vroooom.... vroooooom.... vrrooooom.... like almost stalling/choking down in between each of those vrooooms.
whats up with that? im guessing the carbs get pissy at low rpms sitting on top of the big blower maybe? like there is not enough vacuum signal?

 

Those ones at the track have MASSIVE camshafts. Take away the blower and it wouldn't even run. It's the cam.
Actually a blower (any style) will make the cam seem a tad smaller, and more driveable.
Ask one of those guys with the roots blown vehicles what the duration @ .050" is on their cam - that'll be your answer.

 

I'd pick AFR over Trickflow heads any day.

boost is fun but to make it fun on the street w/a roots blower you'd need a intercooler.. superchiller intercoolers are nice but I dunno how expensive they are. Get a nice Procharger and be done with it.

 

The superchiller runs about 1700-1800 smackers... something i wouldnt do right away if i went with the weiand.

This weekend im gonna do some flow charts with a machine shop and see what the numbers look like.

 

thats wierd, because on a turbocharged car, the cam will act LARGER with the blower. if the engine makes power to 6k without the turbo, it might make power to 7000 with the turbo.

 

Well I mean it'll tame the idle, that's what I meant by make it seem smaller.
Your powerband can still be higher, because it's force fed...

 

you dont normally see blown or turbo'd cars running cams with duration in the 250's @.050 let alone 260's.. people most always run smaller cams with forced induction vs NA.. you have all the forced air being blown in, you dont need a huge cam to allow the motor to get the full boost.. while NA, you have to let the engine suck air in by itself which will take longer thus meaning you need more duration in NA

 

Depends on the application. Street, yes.
Race? No way, bigger is better. There's an 1100HP turbo GN, it runs a 260* ish cam.
That black dual eaton blower mid '70s Vette runs a ginormous cam.
I'm trying to think of other examples that are easy to find. But the 1000ish HP roots blown vehicles use huge cams, FWIW.