I have a 2002 SSEi with the 3.4 supercharger pulley. I am interested in further improving my cars acceleration at all speeds, especially in the 40-100MPH range.

I am considering either adding a Thrasher intercooler or Intense 4T65E HD transmission with 3.69:1 final drive ratio and liimited slip differential.

What mod do you suggest?

My interest in the Intense transmission is really to get the additional torque multiplication, especially in our tall 3rd or 4th gears.

I am also concerned about the stock transmission holding up, if I did the intercooler first. The LSD would also be nice for the occasional drag race or off the line bast. Plus my understanding is you would be able to build more boost at a given speed, because the engine/supercharger woud be spinning 22 percent faster.

My interest in the intercooler is more power, rather than knock retard or detonation issues. I run 94 octane gas at all times, and don't sustain high levels of boost for long periods.

Would I need to go to smaller pulley to realize signficant benefits from the intercooler?

I would have either one installed by Intense at their shop in Columbus, OH. Its about an 8 hour drive for me, and would make a small roadtrip out of it.

I would also get a custom Digital Horsepower chip through them - if I go with the new transmission. You need it with the new trans, to remove the speed/rev limiter and adjust the speedometer.

I would like to keep the cars mechanics as close to stock appearence as possible. My understanding is intercooler is very noticable and requires lots of changes to induction system. The transmission, chip, and smaller are virtually stock in appearance.

The only other mods to the car, is aftermarket wheels and tires (18X85 and 245/45R18 Ulta High Performance all season).

I also have a 2001 GTP which bone stock, besides a set of stock size ulta high performance all season tires (Dunlop).

I have a 3.4 inch pulley on the way for that car, and am considering the new Quafe torque biasing differential and a DHP chip.

WOW ur car sounds awesome. I would go with the heavy duty tranny, because if u add a intercooler and other goodies u will eventually break ur tranny and then u wil have a long road trip/ big $$ to get it repolaced. I would first set up teh car to handle the extra hp then start adding the power pieces.
What i would do now is get a open element arfilter, and do a lot of reading on the clubgp site for info about mods.
if it was my car i woudl do as follows. just to give u an idea
cold air induction - airfilter
smaller pully (Dial ur boost setup)
exhaust
rockerarms
throttlebody
tranny
lsd
intercooler
pcm ( this is last becasue it will be a while before they come out with a pcm for us)

one good thing about our cars is the exhasut setup its 2.5 stock which is larger than the grand prixs

You should already have that trans! Check the "M" RPO codes! What final drive ratio are running right now? Check the "F" RPO codes! If you post these codes here I WILL decipher them for you.

As to which mods....I would go with the intercoller for less wear "n" tear on the supercharger (since I think you already have that trans). All the other "power" mods are great too....usually comes down to "MONEY" though in the end.

I have the stock transmission, which is 4T65E HD with 3.01 "performance" final drive ratio and open differential.

The Intense is a remanufactured 4T65E unit with even heavier duty parts, and adds a limited slip differential.

You can get the Intense transmission with the 2.93 (stock for GTP), 3.29, or 3.69 final drive ratio.

Would it be possible to just put in a new final drive ratio, and keep the rest of my stock transmission?

I emailed Scott Cook and he said the intercooler would really require me to go to an even smaller pulley to see signficant power increases. I would probably have to then upgrade the trans anyway. Although, I have heard that GTP owners are taking their cars to 350HP without problems on the stock trans - assuming they avoid one wheel burn outs.



Thanks,
Anthony

Does "Intense" offer a parts break down of "their" trans? I'm curious by what "they" call HD on "their" trans! I could look into possible diff changes for this trans at work too. What final drive ratio do YOU want?

DeathRat:

I believe intense adds heavy duty clutch packs and a thicker stronger input shaft to their transmission.

It would be great if I could just get a higher final drive ratio, assuming by trans could handle the load. I am really just looking to boost power to the wheels, and take better advantage of the broad powerband - especially at highway speeds.

I guess the 3.69 ratio is perfect for me, signficant torque multiplication without a large jump in RPMs, or putting the engine outside of its sweet spot too early in 1st or 2nd gear.

If you could get a 3.69:1 for me or a similar ratio, where would I get it installed? I am in NJ, but was going to drive out to intense - which is 8 hours away in Columbus NJ.

My understanding is I will also need a speedometer recalibration, and probably a custom chip to adjust rev/speed limiters and shift points - in order to get the most out of the new ratio.

I have an email out to Digital Horsepower who makes custom chips for the 2000 and later SSEi.

If a new final drive and a chip are reasonable price, and low risk, would probably put the same in our 2001 GTP.

I'll check at work today & get back to you ASAP

Unfortunately GM only offers the 2.93 Ratio Diff Carrier (P/N: 24208455) for the (MN7) 4T65-E HD Trans for the 2002 SSEi.

Thanks for checking it out anyway.

I will email scott from and intense and see if they can just put the 3.69:1 in the my existing 4T65E HD. However, I have a feeling they will either advise against it, or charge a lot to have it done.

The intense trans is 3K, and 500 to install. Of course, if I can get the gearing done for less it wold be great. My real concern is not so much the money, but replacing such a critical part.

Maybe there are better modes for me to do?

I guess I could go down to 3.2 inch pulley from a 3.4, and get a DHP chip. I could then do headers to prevent detonation/KR, and get some more upper RPM thrust without losses in low end torque.

I emailed Thrasher about their intercooler and this is their suggestion on mods in order for 3800SC II cars.

3.4 inch pulley (done)
cold air induction (not sure options for SSEI, lots of kits for GTP)
headers and 3.2 inch pulley
Performance Exhaust
Heavy Duty Transmission (with or without higher final drive ratio)
Ported and Polished Heads
High performance cam shaft
intercooler and 3.0 inch pulley