turbo- piston compression realation 420a

ok so now i was reading som forrums and some pple were saying that its better to have lower compression when having a high pressure turbo setup. is this true? because i was going to to a turbo with 10.5 to 1 compression pistons and some type of nitrous setup? this a bad idea?

ok so now i was reading som forrums and some pple were saying that its better to have lower compression when having a high pressure turbo setup. is this true? because i was going to to a turbo with 10.5 to 1 compression pistons and some type of nitrous setup? this a bad idea?

For future reference, typing like you have an education of a 2nd grader will get you fewer responses...and the people who would most definately be able to answer you question will not even bother.

If your planning on boosting it go with 8:8:1. The lower compression ratio will allow more room for tuning errors. You could get away with higher compression if you plan on running a little bit of nitrous. But your tuning will have to be more precise if you run a big shot.

High compression, turbo, and nitrous = very bad idea.

I would keep it between 8.5:1 and 9:1 for sure, and I wouldnt necessarily recommend 9:1 but its the very highest I would go (unless you were on E85).

alright thanks guys. i think i'm going to go with 8.8:1 wiseco pistons. after i get the bottom end of the motor put back together i'll wrk on getting a turbo. whats the highest boost pressure i can run if i get the 800 hp eagle i beam connecting rods and a stock 500 hp crank?

As much as your fuel can supply. Most people run around 18ish daily but race on around 25psi or so. You better have a good fuel management system in mind and something to retard your timing with that much boost.

Easy there Mr. Spilner, step back from the Import Tuner and take a deep breath. Do you really think you'll ever hit 800hp? If so, how are you going to get it to hook? If not, then why 800 hp rods? What fuel management are you going to run? This is not going to be easy or cheap, to take any sort of advantage of 800 hp rods you are looking at ATLEAST like 10 grand. To be honest, I think you're in a bit over your head at the moment.

One thing you should know is that airflow is power, boost pressure (psi) is heat. Yes, there is a correlation, but a t25 on a given boost pressure X will flow a VASTLY different amount of air than a Evo III 16g, a FP Green, and a GT 35R will at that same boost pressure X. As stated above, the fuel system will be one big limitation. Before you can even start your boost fed wet dreams you are going to need some sort of tuning device and most likely new injectors and a pump. Another big one is your intercooling. Too much pressure and shitty intercooling will result in lots of knock which will result in your shiney new motor taking a huge shit right in your lap.

Before you sink your teeth into something really crazy, I would do a LOT of reading if I were you. Theres a few great articles here in the tech article section as well as at DSMtuners.com. And of course, we'll be here every step of the way.

Check out 2gnt.com A lot of people over there have boosted 420a and there is so much info on there. Just search and you will find everything you need.

i'm shooting for 400 hp. i just want the 800hp rods because when doing high rev's (wanting to go 7-8 thousand) usually the rods are the first to go. after i do the bottom end i was planning 44 lbs injectors, high rate fuel pump, fuel manegment(http://www.ci-motorsports.net/store/product.php?productid=525) and a boost controler (http://www.ci-motorsports.net/store/product.php?productid=527) whats your guy's opions on this setup?

In going for 400 hp, I doubt you would break an aftermarket rod. Just get the standard Eagle ones. I know a guy thats done a lot of fucking around with Haltech and after that I wouldnt recommend it. I would run AEM EMS if I were you. Realize though, that neither of those two management systems are exactly plug-and-play. A great deal of knowledge is needed to tune with them properly.

Other than that, have you started looking at anything else? You're going to need intercooling, exhaust, a decent turbo, intake manifold, cams, a built tranny, a decent clutch, drag slicks, etc.

Also, that boost controller is rediculous, I would never drop $500 for something like that when a MBC would do the job just as well for literally 10% of the price.

I've heard bad things about the stand alone. Use MegaSquirt. That will probably be the best way for 400hp for our cars. It's a pretty easy setup and can be tuned on a laptop. Either that, use the AEM EMS. Costly though.

Go with megasquirt, that will give you fuel control and ignition control.

well found a megasquirt for 795 ( anybody find one cheaper?) but looks like an awsome system. i'm in the process of getting a manual tranny, but what need sot be done to it so it can hold the power? and yes, i plan on upgradign the cams, lifters, rockers, valves, springs, injectors, ci turbo, arp head studs, fidanza axle and a bunch of other little stuff. if anybody has some recomendations, feel free to post!

I beleive you can get it cheaper than that. You just have to search around.

well found a megasquirt for 795 ( anybody find one cheaper?) but looks like an awsome system. i'm in the process of getting a manual tranny, but what need sot be done to it so it can hold the power? and yes, i plan on upgradign the cams, lifters, rockers, valves, springs, injectors, ci turbo, arp head studs, fidanza axle and a bunch of other little stuff. if anybody has some recomendations, feel free to post!
gathering from every one of your posts, either you have to much money to spend, to much time, a little of both, or none at all and your just asking these questions to act "cool" first off, an auto-to-5spd swap isnt exactly a walk in the park... you should be focusing your questions regarding that project before you go off talking about a 400 hp 420A RS... theirs alot of work that needs to be done before you even get to 200 hp... then again, why do all the work if your asking about buying a GSX? Just take it one step at a time man, trust me! it'll work out better for you, as well as all of us... start small... maintain, build up, race, blow up, rebuild, race, blow up, rebuild, race, blow up, etc. (in that order!) but you cant "build up" with out maintaining, you cant (really) race with out building up... see? 1 step at a time bud! :2cents:

first off i never posted anything about buying a gsx. i'm leaving mine fwd. and yes i know its alot off work and i'm also busting my ass at work to pay for these parts. and i know its going to take a long time before my goal is reached.

44 lb injectors will not get you anywhere near 400hp

gathering from every one of your posts, either you have to much money to spend, to much time, a little of both, or none at all and your just asking these questions to act "cool" first off, an auto-to-5spd swap isnt exactly a walk in the park... you should be focusing your questions regarding that project before you go off talking about a 400 hp 420A RS... theirs alot of work that needs to be done before you even get to 200 hp... then again, why do all the work if your asking about buying a GSX? Just take it one step at a time man, trust me! it'll work out better for you, as well as all of us... start small... maintain, build up, race, blow up, rebuild, race, blow up, rebuild, race, blow up, etc. (in that order!) but you cant "build up" with out maintaining, you cant (really) race with out building up... see? 1 step at a time bud! :2cents:


Im going to pull about 300 whp from my set up but i've also already invested over 4 K into mods and its not even in the car lawl. Then again when I am done with it , it will no longer be a RS. so :/


eclipse787 , I can tell you this , I spent 1200 just to have the transmission ALONE , already removed from car , delivered to shop and rebuild with hi-perf internals. It's not a cheap road , it's not an easy road. If you actually have the money you say you have , build smart not expensive no point in wasting excess money on something that doesn't provide power and could be purchased for way cheaper and do just as good of a job as Thor says.

Also if you are going to be trying to hook with either 400 whp or 400 chp you are going to need an insande clutch package , i have a stage 2 kit with new everything and flywheel and that ran me 700 , as far as turbo manifolds go it's anyones ball park there I just ordered a short log off ebay and I expect it to break within the first 500 miles of breaking in my new motor..lol what can you expect for 200 :/

I know a lot of people dig the 16G evo turbo but I dont think it will provide enough for 400 hp on the 2.0 DOHC least I have yet to come across any word for that. Other things you need to consider is if you are looking to drive it daily you better get some better brakes , stock brakes won't work as well with such acceleration and braking with a 400 hp car unless they came with a 400 hp car , know what I mean ? also another factor is suspension ..eliminate wheel hop , handling , better response im already almost 900 deep in my suspension and not even done yet..:/

so like they say take it slow , read up , do it righ t, have fun , race and learn.

The stock tranny should hold up to 300whp but if you have the money I guess it wouldn't hurt to build it.

Alright guys, you make it seems like this stuff is a walk in the park. Well heres some advise, you need to get your turbo kit on the car and work out all the kink first. You cant say Im going to make 300whp when you right off the bat. Anyone can buy all these nice parts but you have to know a lot about this motor and alot about tuning to make it all work. I suggest you install the kit and run it at low boost for a while till you figure out how the tuning works and make sure everything works like it should. Then gradually turn the boost up and you will put down some power.

I just wanted to say something about the whole high compression, nitrous/turbo thing.

It's kinda a myth that nitrous is bad for high compression engines. While essentially a high compression motor is not ideal for the setup, that does not mean that it's not possible. I mean crap if you look at Pro-Modified, those run at a compression of 15 to 1 and have alot of nitrious. (Granted those are also professional built race cars)

When you are running nitrious on a high compression engine, you are going to need to retard the ignition timing more and user a higher grade of fuel than you would in a lower compression motor to net the same results.