Which boost would you use?

[Jon89LE]

Im aware that the N2O is harder. Your freezing the block pretty much. I cant agree with you on the blower belt slipage though. Most roots blower that get placed on older V8s have ribbed belts, from what ive seen, so they cant slip. By ribbed i mean like the timing belt on the DOHC motor. With the regular serpentine belts they do slip. The GTP guys who run the MP112s have that issue and ive heard of a few new Cobra guys with the same issue.

[geoffinbc]

Aaron superchargers dont need to be intercoold but neither do turbos. It just helps cool the air so you can run higher boost without detonation and get a denser charge. Belt slipage will occur on some setups this could be avoided by installing idlers to get a higher arc of contact on the pulley or increasing tension (increasing tension will shorten belt life). Slipage is sometimes a good thing it will help prevent damage to the blower and motor.

[TurboZ24]

Well, a lot of people ask this question.

As efficiency goes, turbo's are going to be your best. You would see the most power gains from turbo's, simply because they compress the air more efficiently and don't run off the crankshaft (technically they increase back pressure, reducing HP a little). You would probably also see better economy, since the turbo doens't really drag the motor down when it's not boosting. My first turbo car only lost 1 mpg city/highway.

As for lag..... A proper turbo setup will not have a ton of lag. My car still get's full boost (12 psi) by 2700 to 3000 rpm. Most people doing turbo setups either don't care about the lag or they don't seem to realize peak HP means nothing if you don't have a good usable powerband. I've seen lot's of really high peak HP cars run and they are all slow on the track, simply because they have power for only 1000-1500 rpm, that's it.

I see the only true positive for superchargers (centrifical or roots) is less plumbing.

Actually, I'm running mid 12's right now (12.49) and hopefully will hit 12 flat without additional boost (replacing headers, crossover, turbine upgrade, and a little retuning). Then if the tranny doesn't explode (again), I'll boost it up more.

On LT1/LS1's, a friend was going to get a supercharger kit for his Camaro to attempt to compete with mine. When he talked to several shops and discovered that even with the minimal kit, they indicated that a lot of the cars ended up with detonation damage and failure after a year or two, so he decided against it.

[StudlyCamaro]

But why would my cam which has more exhaust duration be more suited for nitrous?

when on crack, the car will suck as much air as it can just like a N/A car, however the air is more dense, therefore when the combustion occurs there is more exhaust in the cylinder and it needs more time to get out, hence the longer duration on the exhaust side for nitrous

Nitrous is just another type of forced induction basically, isnt it?

not really at all.. if you are spraying your car, you are getting more are into the cylinders, but its not because you are compresing it, you are cooling it and it becomes more dense , thus more O2... your motor will still be working under vaccum instead of boost (hence why if you hook up a boost gauge to a N2O car , you wont read any boost while juicing)

Aaron superchargers dont need to be intercoold but neither do turbos.

with forced induction , you are cramming the air into the motor.. it will heat up due to the compression (same princilpe for why N2O cools the air(but the oppiset)), thus the need for an intercooler if you are running much boost to avoid detonation (especially for all you alumnium headded guys)

[Anonymous]

Ours is a weind 142, uses a serpentine belt, not a ribbed belt. We run the mtoor to 6300, have 540hp dyno sheets, and it doesn't slip as the digital gauge was reading 9.85 psi @ 6300.

[Jon89LE]

Aaron, it must be the type of belt setup, since i know for a fact many of the blower guys i talk to either chew belts or have them slip.

With the nitrous, i know what your saying with the nitrogen and oxygen being more dense. I didnt know the thing about the boost though. Its like i knew it, but it never clicked . The denser charge is causing the power, not air being 'forced' in, duh. So thanks for that one.

Curtis,
You mentioned that the Turbos are more efficient, and i can agree with you on that. With your setup, is the transmission the only weeklink holding the motor back or do you also have airflow problems, or lack of air for that matter? Your 12.49 would maybe equate to a high 12 to low 13 on a Wbody due to the weight im guessing. Im just trying to see why the 3.8s can break 12s with the only major mods being heads and Cam. Also, If you have an AIM or AOL i could talk to you through that instead of going back and forth through the message forum.

[TurboZ24]

With your setup, is the transmission the only weeklink holding the motor back or do you also have airflow problems, or lack of air for that matter?

Actually, the problem I currently have is back pressure between the turbo and the heads. After all the work here and there I did on the motor (excessive roller cam and increasing the head flow rate 59%....), the headers, crossover, and turbine housing/turbine are just too small and arn't allowing the exhaust out of the motor. My engine is currently exhaust limited to 12 psi. In fact the crossover is currently cracked, wide enough to put a zip tie into, almost all the way around the pipe, but it isn't affecting boost.

I am about to get new headers, new crossover, and upgrade the turbo (turbine side only) to solve the severe back pressure problems.

I do have the car setup for dual stage boost. I'm currently close to the limit of the tranny at launch, but will raise the boost after the car is rolling.

Yes, I have all of the above. AIM turboz24 ICQ 14305985

[TurboZ24]

Well, as for 3800's..... First, the supercharged ones are already low compression, built for boost. I'm sure any 3800's running the 4T65E and getting into the 12's no longer have stock trannies. I also see a lot of posts about that, but from what I understand, the 3800 is a little prone to detonation, even at low compression. I think almost all those guys run water injection, propane injection, methanol injection, or run 100+ octane gas when running 12's.

[phantom505]

I've been running 9 psi on 9.6:1 forever.

[Jon89LE]

Did you turbocharge the car after a previous high compression rebuild

[bszopi]

No, he is running 9psi on a stock compression 3400. And phantom... forever? You've only had it like that for what... a year? MAYBE 2 at the most. That is far from forever, even in a non-literal sense.

[dbtk2]

Well, as for 3800's..... First, the supercharged ones are already low compression, built for boost. I'm sure any 3800's running the 4T65E and getting into the 12's no longer have stock trannies. I also see a lot of posts about that, but from what I understand, the 3800 is a little prone to detonation, even at low compression. I think almost all those guys run water injection, propane injection, methanol injection, or run 100+ octane gas when running 12's.

My dad ran a 12.408 @ 108.27 in his '02 GTP with the stock:

Transmission (except for shift kit and an LSD that didn't work)
Block
Crankshaft
Connecting Rods
Pistons
Camshaft
Lifters
Heads
Ignition Coils

well hell, it would be much easier to say what wasn't stock.

That was with 15psi boost and the stock 15* timing advance. No weight reduction other than removed spare tire/jack, and removed cat-back exhaust (which was removed for flow not weight savings, but it did save ~70lbs). And it was all done on 94 octane pump gas, no water injection, propane injection, or methanol injection, and most importantly of all, no nitrous.

Aaron, it must be the type of belt setup, since i know for a fact many of the blower guys i talk to either chew belts or have them slip.

My dad has never had a problem with belt slip or chewing up belts on his GTP even with a 2.6" pulley (1.2" smaller than stock, ~15psi boost). Its just the setup I guess. He uses a factory style 6 rib belt with all factory idlers & tensioner, the only thing different from stock about the belt setup is the smaller supercharger pulley.

Shawn

[Jon89LE]

2.6" pulley and only weight saving mods? That doesnt sound right to me. Ive even talked with the guys over at Intense and anything smaller than 3" needs a "few" other mods first.

[dbtk2]

2.6" pulley and only weight saving mods? That doesnt sound right to me. Ive even talked with the guys over at Intense and anything smaller than 3" needs a "few" other mods first.

No thats not what I said. Most people running that fast have signficant weight savings mods and/or big cams and nice heads. I was just stating that he doesn't have much weight reduction, and he doens't have a big cam or P&P'ed heads. He has significant mods, don't get me wrong, but just not internal engine work. You can look up his 1/4 mile time on club gp if you think I'm BS'ing. It should be like 22 or 23 on the national link, and IIRC you can click on it and see mods and stuff...but I don't remember I haven't done it in a while.

Shawn

[Jon89LE]

Thats pretty good then. Im surprised he got that low without even head work. If you could, just for 411, post up his mods when you get a chance.