Celica Forums General Discussion Exterior Lowering Compression in GTS

i am considering running n2o and was just wondering how i could lower the compression on my gts so i could run a 75 shot and if that loss in lowering compression would be made up for by the bigger shot (50vs75)

get a PFC and retard your timing when you run the nitrous...

You don't need lower compression for a 75 shot. Just use colder plugs and 100 octane gas and you should be fine. Make sure you aren't running lean also of course. I talked to Thomas Hornig who ran a Nx 75 shot fine with no problems on a '03 GTS. He only mentioned he had colder plugs, but I assume he uses higher than 91 octane. He uses stock 11.5:1 compression. He does not retard the timing. BTW, Thomas' best 1/4 mile run was 13.716 s @ 99.89 mph at 1200 ft.
NebraskaGTS, I gave you info about the MSD window switch before, but even though that may work, the Mallory window switch is better (you don't need those modules).

PFC doesn't work with an auto does it?

i am worried that i might be running lean or something, so i am kind of hesitant to run n2o at all. i think something is messed up with my Intake b/c off of my "launch" (torque breaking) my engine really bogs, and sometimes when i start my car up it barely moves even if i have it floored, and then all of a sudden it will take off at about 3k and the Intake really is sucking hard. anyone know what this problem might be?

I think what you are talking about is normal. I believe its because of the lack or torque low end like that. Try gassing it up a little and feathering the clutch during take offs.

i would love to be able to feather the clutch, alas i can not

Why don't you try setting the e-brake on the line, and releasing that as the yellow light goes to green? I know the accepted technique for autos is the regular brake pedal, but maybe the rear parking brakes will let you spin your front wheels at a higher rpm before you launch. Also, coming off the rear e-brake might induce a forward weight transfer on the launch, which is what you want on FWD. Just don't floor it too much...or you might drag your rear wheels and red light, hehe.

yeah, i have thought about that...i pm'd you back on your offer, but won't be able to talk again till later b/c i am heading to work. i am pretty intersted though. thanks

So long as your nitrous kit is a wet system, you can use a slightly larger jet for the fuel, this should enrich it enough that you won't get any detonation, don't go too big on the jet, or you will need to worry about bogging or fuel puddling. Once again, try to run at least 93 octane like many others have recommended. Wet Kit's are safer imho, and are less likely to cause detonation in the first place. Seeing you run an automatic, you will have an eaisier time running a wet kit anyways, since fuel management options are limited.

PowerFC should work on an auto, with the right program and harness. Brash Boy sells PowerFC systems for the auto GTS, so that's a good starting point. Also may want to look at split second for your fuel management needs.

Alcohol or water injection may be another option for you, but it's not for everyone, still, it's an option.

The mallory switch is cool, just make sure you dial it in properly, a switch that uses pills is a little more accurate and safer. if you go with the mallory, make sure it's installed in a place where the knob can't get jostled out of place, or put a piece of tape over the knob once it's dialed in so it's setting doesn't get out of whack. This is if it uses a dial or knob for setting the trigger RPM, some units use jumpers or dip-switches instead, which is way better in terms of control/safety.

Oh, and that lag when you first launch is pretty much something you need to deal with. Try rolling into the throttle instead of mashing it. Also you may want to look into an aftermarket torque convertor with a higher stall speed (about 3K stall should fix the problem) Level Ten is the only source for the time being. It'll be a custom job, but should be affordable.