Ok i have a stock 4.2 that I installed a MAC air intake on, ive lost a lot of low end power, but have gained in the mid and high. How do i get that low end torqe back. I was thinking a chip, but now im afraid of exaust because of what ive read about losing low end. What do you guys think i should do?

 

Low end... chip would help however...

Our engines have no low end... only way to compensate is GEARS!!!

get 3.73's on 5spd or 4.10/4.30's on automatic running stock 29-30" tires.

 

I agree with Talley.

Chip it and get gears and you will feel stronger low RPM response.

Avoid mods that greatly increase the diameter of the tubing leading into and out of the engine. This means large air intake tubes, large diameter exhaust tubing, etc. It will slow down your air velocity too much at low engine RPM. By all means mod the exhaust, just keep the single 2.5" tube set-up. Make sure you are using a cool air intake set-up. Hot engine air will also kill you on the bottom (and we don't have ANY torque to spare).


Hope this info helps,

---J

 

Ok, if i get the gears, which ones would be best, 4.10s or the 4.30s, will I still be able to run highway speeds (80mph or so) without being over 3 grand in rpm?? And last but not least, wheres the best place to buy them (cheepest/reliable)??

 

4.10 - conservative choice, very streetable.
4.30 - mildy streetable, more race oriented.
4.56 - very race oriented, more for full-on drag racing.

The dealer is who I'd have put them in. Also have them reflash your ECU for the new gears. Try to stay with a reputable shop if you don't go to the dealer, though.


Later,

---J

 

I would assume you have the automatic...

80MPH on 30" tires

3.55's = 2,258rpm's

3.73's = 2,372rpm's

3.90's = 2,481rpm's

4.10's = 2,608rpm's

4.30's = 2,756rpm's

4.56's = 2,900rpm's

 

Just FYI, I just put 4.10s in and my gas mileage has not changed a bit(not yet anyway), and I've been pretty heavy on the throttle. After a full tank of gas, my mileage stayed the same and that included about 150 straight highway miles.

 

I have a 4.2 5sp, i am thinking about changing my 3.55 non LS to a 3.73 LS. I am running larger tires then what the door pannel calls for 265/75/R16 vs 235/70/R16. Just trying to work out all the details , right now leaning towards an eaton.