vw 16v turbo high compression and non intercooled

[nitrous16v]

Hi, i have a 91 vw gti 16v with stock motronic uel injection,(chippable) that was built N/A with je 10.8 to 1 compression pistons,all arp hardware, supertech valves,mild cams,etc. so i ran across a kinetic turbo kit for a great deal, mitsu 16g turbo non intercooled low boost 5-6psi,tial 38mm wastegate 5lb spring(supposedly 30-40hp gain to a stock car) included a split second aic 1 (up to 2 additional injectors using 1of the 2 lucas 37lb injectors included) so i put the kit on and heat soak is obvious when its hot, i also have a innovate motorsports lc-1 wide band a/f monitor. my question is due to the design of the fuel injection system and the cars manifold/throttle body intercooling is basically impossible without major changes, the car runs ok,i did get a custom chip from neuspeed in california that the timing flat lines at 20 degrees at full boost or approx 3000 rpms to red line. the car has nice mid range but falls off around 5k on 93 pump gas unless i run 100+ oct fuels then it runs better(high compression obviously) So would lowering compression by 1 point help?approx 10.8 to 11 to 1 now so down to 9.8 or 10 to 1, (i have a head gasket spacer with new gaskets i havent installed yet) and or should i add a water injection kit? i could use the 2nd additional injector location to put the Water Injection nozzle, i daily drive the vehicle and i tow my rally car with it.

[Richard L]

I think your setup will benefit well from water injection for sure - no doubt whatsoever.

[nitrous16v]

any particular brand or style? with the older non mass air fuel injection and lack of tunability is there a controller or style of water/meth kit that will work best since i basically only have manifold pressure to go off of. should i still lower compression? if i lower compression can i put a 8lb spring in the wastegate so i can run more boost?

[Tjabo]

Wow, you're brave to be boosting a high compression motor like that, especially with a small turbo that will probably spool up before peak torque, and without intercooling! ! ! :shock:

FWIW, you can certainly have a better result if you reduce your compression ratio and use more boost. Further, you need to get a very good water injection system to act in lieu of an intercooler. Aquamist is the undisputed best, and since you aren't paying for an intercooler, tubing, and connectors, you can justify paying the necessary price to buy the best W/I system and keep your motor together.

If I were you, I'd go with the W/I first (immediately actually), and tune with that system installed, using a good pair of det cans to monitor subaudible detonation. You can use methanol in your water mix to supplement your fuel if you need to so you can keep your AFR under control as you inevitably raise your boost level! :lol: You might find that with a top notch water/methanol injection system, you can avoid reducing your compression ratio.

I'm running a fair amount of boost currently on 9.6:1 compression, and it is more than optimal, but I plan to crank it up a bit more when I get my W/I system running here in the near future.

Hope this helps, but if nothing else, at least it's a bump!

Thad