High compression isn't needed for a turbo car. It helps very minimally. I would keep your 11:1 compression and raise the boost.

 

Supercharged autocross car.

 

this is a great idea, great off boost response and faster turbo spool. Looking into running 100% methanol injection with numerous fail safes. You have to get the octane level up

 

When you have a slug of a motor out of boost you certainly can't. My old 8.2:1 motor would get into power quick, but it was a dog just riding around compared to a stock GSR or my old ITR or something of that nature.

 

Really? i have the exact opposite response. I have a 7:1 comp d16a6 with a big cam and spool instantly. (yes i have a smaller tubo but it still spools way faster then my stock compression engine. 1000 rpm faster to be exact)

Remember when you drop the compression for boost things that work with high compression don't work the same with low compression. I put money on you having a turbo set up that wasn't thought out with low compression in mind and this "sluggishness" was the result.

To the op - Just because it is possible does not mean it is a good idea. I can't see why you would want a volatile engine that's on the edge of blowing up just to get "sick response on the street".

Just saying you could drop a small gt turbo in your car and make 450+ hp. I'm pretty sure that's plenty of the street seeing as it would spin through 4th.

 

Care to elaborate on how you make a 7:1 motor outperform a 9:1 turbo engine? Kinda goes against everything I've always researched.

I do agree that just because it can be done doesn't make it a good idea.

 

I build turbo manifolds in my spare time. I have a fab thread about my manifold.

I built a small volume small runner manifold. This works for my flow requirement in my rpm range (7k rpm redline), engine size, efficiency etc. Like i said one needs to build a setup around his engine and what it will be used for.

Would this be ideal in a drag oriented car? Not likely. But in a street car shifting the power band down a bit is a good thing imo. ( ie: higher velocity, less flow)

 

Why would you even go that low in compression? Theres no way thats even efficient

 

$120 vitaras + d16a6 = 7:1 comp.

I do love hearing people say it will spool like crap. eh it's works just fine.

Also efficiency is relevant to a point. Does it take more psi to make x hp? most likely. But i can't see how running 14 psi over 9-10 psi is any sort of con. Just remember people were making extreme power in the days of 7:1-8:1 comp turbo cars.

 

I'd do it.. I had a 14.5:1 compression B16 on a direct port 200 shot that made over 450HP with timing left on the table, on a mustang dyno. You'd be surprised how far E85 will go. If you know what your doing, have a competent tuner, and use your head, I don't see why this wouldn't be a killler setup..

I do agree with Tony The Tiger that its probably better to do it with chamber size and valves and what not, but I've done MAX DOME pistons before and made great power N/A, so its hard to say without doing 2 identical motors back to back to see how much the dome actually disrupts the flame.

Doo itt.. And if you need somone to tune that bad ***, lemme know I'd love to do it.

You definatly need to get cams with a good amount of overlap, just wouldn't go to high on the lift. I did Toda Cs on my max dome setup and made 255Hp N/A on a B16 crank.

 

I see nitrous as a whole different animal. You actually have adiabatics working for you. Where boost will increase IAT's because you're compressing the volume of air, nitrous will lower your IAT's since the volume is being decompressed. The lower IAT's will allow the higher compression without detonation issues. Running higher compression with nitrous is a tried and true method, but with boost, its not as beneficial.

BTW, I read on HPD that you guys do ultrasonic cleaning. Would you mind shooting me a PM with a pricing breakdown? I have a iron V8 block and a couple misc things to have cleaned.

 

listen to this guy, one of the best around!

 

I see nitrous as ALOT more volitile a situation than boost. Sure it lowers charge temps, but its also way more viscious when it burns (just from what I've seen, not claiming to be a nitrous expert)..

Yes we do have an ultra sonic, but its currently down, burnt up two amps in a row, has a short in the tranducers on one side so were shipping it back to have it warrantied. I'll let you know when we get it back, but it may be while.