So im upgrading my lt1 383 i want to make 500 whp with some afr 195 comp or ai 200cc the guys at ai told me they have built 383 setups with solid roller cams that made 500 plus the 195 afrs only flow 18 cfm more than the ai 200cc Imo i dont think the extra money is worth 18 cfm the car is going to be a weekends driver only and i am going to have 12.5 comp. I want to run 10s all motor so what do you guys think afr or ai has any of you run a ai or afr setup and if so how did it run i am going to run a solid roller.

 

I run AFR220s with a SR cam (248/254 @0.050 and 0.670/0.68X) in a 408cid. Car runs quite well.

 

What kind of hp are you making and would you recommend 12.5 comp. On a 383

 

..... 12.5:1 puts you in a race gas category , unless you have a "source" for cheap octane ... I run E85 with 13:1 but its not available at every gas station ..... SR 421 Brodix 227's making about 600 hp @ the crank .....

 

If you want 500 at the tire pay for every last little bit
18 cfm is worth going after

11.5:1 383 260/268@050 640 lift 108 lsa solid roller ported single plane 850dp Dart 230cc head doubt Im making anywhere near 500rwhp.
Takes more than most would think.

if you havent bought heads go bigger, at least 12-1 and a healthy solid roller

 

12.5 will need race fuel all the time, even when on the street, you may get away with 100 octane unleaded if not to much timing, watch the spark plugs for the little silver aluminum bits that would show detination look with magnifying glass after wot runs. May need 108 or 110 but I think only available in leaded.

 

With a head flowing 300 cfm or close rule of thumb is that the cat should make 600hp what is the limiting factor of the lt1

 

..... Its going to take a little bit more than some cheap heads and a solid roller cam to get your vette into the 10's ... just sayin' ..... Isn't it interesting that AFR 195cc heads outflow the other 200cc heads by 18 cfm ? ..... Keep cutting corners and you'll be lucky to see 11's .....

 

My old 383 LT4 was 11.5-1 with AFR 195cc competition LT4 heads.Mild hyd roller 232/236 @ .050 .Factory LT4 intake.1 5/8 long tubes.six speed with 4.10 gears.Made 441 RWHP so 500 is doable.It ran quite well.Trapped low 120's in the quarter mile but traction was non existent.
It might be done with 195's but a bigger head would get you there easier with enough compression and cam IMO.

 

My old 92 is a pretty serious build for a true drive anywhere, pump gas, hyd roller cam LT1 based engine. Ended up with 487RWHP. It wold run 130mph in the 1/4 but I never got that 10 sec time slip. Hundreds of low 11 sec slips. Being a 6spd it broke the rear end or blew the tires off any time I tried to launch it hard enough to do anything. Best 60ft I could get was 1.77....... there's alot more to it than just motor and hp.

I've built engines for many people here on the board and one in particular for a really good friend thats in his 93 Vert made about 470RWHP thru an auto trans. His cars been just as fast ET wise as my 92 but runs 125mph, just because the 60ft was so much better at 1.60. Got a new converter in it now and waiting for the time to get out to the track and get his 10 sec slip as long as the converter gets his 60ft in the 1.50s....

Not happy with always tearing up the 92 but unwilling to put an auto trans in it, I found an 84 that needed a motor and transmission.... decided to see how fast I could go with a true street car and later how fast on the stock IRS. When I first built my 84 and it was still mostly a street car, on motor it went mid 10s at only 124mph but it had a 1.41 60ft on motor. Went mid 9s@144mph on 200hp nitrous and eventually after alot more motor work, 8.60s@155mph. I put so much more work into the suspension and transmission/converter (th350 conversion) in the 84.... and that made all the difference because the engine I orginally built for it wasn't as good a peice as the engine in the 92 but it was so much faster on the track.
Will

 

FWIW, my OE ported heads flow the same as the AFR 195 Competition heads. My 396 with very small lobes but healthy overlap (108* LSA, hydraulic roller) and about 11.3:1 CR (I think, going from memory here) and a ported LT4 intake probably makes 420rwhp. With a significantly more aggressive cam (bigger lift and duration) and a single-plane conversion intake it made 460rwhp, but wasn't very streetable.

With a solid roller, the 12.5:1 CR, and the AFRs you might see 500rwhp, but it won't be a car you'll want to drive on the street and it will need race gas. OTOH, my car with the small cam is very streetable, with tons of midrange power. It runs on premium pump gas and still gets 26mph on the highway. It slightly pulls on a stock C6 Z06. Based on that, it should hit 125ish for trap speeds based on what a C6Z can do. It would probably run high 11s with me driving it on street tires, LOL. With steeper gears and drag radials and someone willing to abuse the ZF6, it could probably run 10s (again, "stock" Z06s with tires have been doing this forever). It is fun on the street and a hoot for autocrossing. On a road course it would just enough to keep you happy.

So you really don't need 500rwhp and an unstreetable cam and CR to run 10s. You need a car that is set up to launch hard and consistently and a willingness to powershift (or an automatic with a good torque converter). See post #11 for more on this. OTOH, 18cfm is a crapload of airflow, and I wouldn't give that up if I were you. As others have already said, if you are planning to cut corners on heads, then you are going to shoot yourself in the foot.

 

AFR flows its heads on a 4.060 bore. Who has a LT1 with a 4.060 bore? Reason they flow with that bore it is to inflate numbers. I personally would go with AI. Proof is in the results: http://www.advancedinduction.com/Res...esultsMain.php

 

..... My Bad ! ... I should have done more research before referring to these as cheap heads ... cheap they are not ! $1795 to CNC port YOUR OEM GM cylinder head castings .....

 

I don't think a 0.03" bore difference can explain 18cfm difference! I would suggest if the OP wants to go with a porting job on OE heads, he should consider Advanced Inductions' larger porting options, such as their 215 Competition package. As my own LT4 heads show, one can get a lot more airflow out of OE heads than the 200cc package shows, and that flow is critical to getting real-world power numbers he is looking for.

 

LT1 heads are thin cheap castings with cheap GM low grade parts.Buy the AFR's and build the motor right.Why is there never enough time to do it right the first time?But always time to do it twice.