I've recently decided that I'm going to most likely be bored enough this winter to necessitate the purchase and installation of a turbo on the S...sounds like a good excuse right? But I had a few questions and I'm sure that there is plenty of experience on the matter floating around. I haven't fully decided b/t the Inline pro or the Ultimate racing kit but it will be one of the two. Both seem to push about 7 to 8 psi with the option of boosting more. I do want to keep the S streetable and reliable, but I also know that with my personality I'll eventually want more than the standard 300-350 whp and I'll want to turn up the boost a bit. I know the warnings about blowing the rear diff, and I do not plan on launching so that isn't my main concern. At what point should one upgrade the internals of the engine to hold the boost without concern? The majority, if not all the kits maintain that they can be run on completely stock internals, but they do not offer any indication of when stronger internals are needed. Also, what is the correlation between boost and compression? I know of course that if you raise boost levels, you should lower compression...but why exactly and how important should that be in my installation? If and when I do upgrade internals I will need to know for the ordering of the pistons/head gasket. Well, I do know that boost obviously raises pressure inside the engine, in effect temporarily raising the compression ratio of the engine as boost rises...but why do you get more power by dropping compression and raising boost? It seems as if you lower compression and raise boost, you'll just meet in the middle For example (I know these numbers aren't right) say stock compression is 11:1 and you have 7psi of boost so your overall compression at full boost is 18:1. Now say you lower the compression to 9:1 and boost 15 psi then wouldn't the final compression still be about 18:1 since you lowered one and raised the other? And why would this produce more power? I would assume it has to do with the CFM of air flow into the engine, you get more CFM (theoretically) with more boost so if you lower compression you can boost more air in without too much pressure? Thank you ahead for any assistance, also, FYI I probably would shoot for 400 to 450 hp if I choose to boost more once it's all said and done.

 

Cheak out this link:

http://en.wikipedia.org/wiki/Compression_ratio

There are many factors, but you can use water-methanol injection to use higher boost on your stock internals. There's a few good threads on this forum on this.

I wouldn't go above 8psi on stock compression.

 

its just a safety thing. most people stay around 8-10psi on stock compression. we lower compression to increase our 'safety zone.'

for most setups under 500whp upgraded internals are not necessary. the simplest way to lower compression is to use a thicker headgasket - thats it! our engine internals are forged to begin with so with lower compression you'll have a motor well suited for high boost numbers (somewhere around 22psi seems to be the max as per inline pro...)

however, if you lower compression you will NEED to make more boost to create the same amount of power. 7psi @ 11:1 compression will yield more horsepower than 7psi @ 9:1. granted, this is no problem since you'll have the window to run ~20psi depending on your turbo and fuel situation.

i've been through several setups, so if you have any questions please dont hesitate to pm me!

 

Well first let me say this.....dont get an ultimate racing kit. The IP kit is really nice and a LOT better than the UR kit would be. Having said that I just installed my PFAB topmount kit and its around the same price as the UR kit ( cheaper than IP ). Its really nice...check out www.pfabrications.com and see what hes got to offer.

I am going to run 10psi on stock CR with pumpgas, and 16psi on racegas. With racegas people are making LOTS of power on stock CR and internals and thats the route im going. Good luck with it, I would use a GT3076R for your power goals!

 

i agree you shouldn't go above 10 psi on stock to keep a safety margin, but dont be afraid to go up to 10 psi most if not all greddy kits do that and they run on a fully stock engine

 

Depending on your mechanical skills and knowledge. Don't be afriad to piece together your own kit. I have done it and spent alil less TOTAL than what it would cost you for a full kits that are out there. Check my sig for my setup and numbers. Pm me for any questions I'm always willing to help.

 

Awesome thanks! Yeah I hadn't heard much about the Ultimate racing kit, but it seemed as though it had some good components...Inlinepro seems to be the norm and if everybody else is doing it without trouble it should be a good place to start. As much as I would like to piece together my own kit I am still a novice with FI, and although I have fairly good technical knowledge I don't know enough about turbo setups yet to pair up the turbo/manifold/wastegate and intercooler piping to make it all work I'm afraid...I know there are different styles of manifold assemblies for example, but will any turbo/wastegate pair up to any manifold, or does it depend on whether it's a top mount or bottom mount manifold etc, and I'm not sure how to tell which intercoolers have the piping setup for each turbo setup, not to mention the downpipe! ...so a kit may be the best thing for me...thanks for the help though. I'd read about the thicker head gasket and it seems that would be a cheaper and easier/faster way to drop compression a bit to see how I like it, and since we do already have forged internals that would probably be a better choice since I'm not planning on hitting 20psi anytime soon! I'll keep ya posted on what I decide and I'm sure once I get started I'll be PMing the living hell out of some people...ha ha