2.4 exhaust and pulley question

[2fast4u1989]

I have a 1999 2.4L SE.I was wondering what size the stock pipes were.also how much power(if any)would a Lightened Billet Aluminum Crank Pulley add?I saw one on Z Spec and its only $100.thanks

[98BlackGAGT]

You can get a good BOMZ underdrive pulley on ebay too for a lot cheaper than that... I did, it doesnt add power, but it gives you a faster and smoother rev, before i did it when i would down shift i would get the rpm bounce and now it doesnt do it at all, plus it revs up faster when your in neutral... it claims to give you HP but im almost positive it doesnt...

[urweak]

I have a 1999 2.4L SE.I was wondering what size the stock pipes were.also how much power(if any)would a Lightened Billet Aluminum Crank Pulley add?I saw one on Z Spec and its only $100.thanks

I dont know the stock size, but increasing the size to 2 1/4 inch from say the cat back might net your 5-10hp.

There is another company out call unorthadox racing that makes these pulleys, you might want to check them out.

There is however some debate on this mod, some feel that the replacment of the balancing pulley for a lightweight pulley will cause engine damage.

If you still have questions just ask, its late and ive been up all night doing trig homework so my brain is fried.

You can get a good BOMZ underdrive pulley on ebay too for a lot cheaper than that... I did, it doesnt add power, but it gives you a faster and smoother rev, before i did it when i would down shift i would get the rpm bounce and now it doesnt do it at all, plus it revs up faster when your in neutral... it claims to give you HP but im almost positive it doesnt...

it doesnt add HP like say an intake, header, or cam would. What it does is frees up wieght on the belt drive, and by having to turn less mass (turning the pulley) the engine losses less power trying to turn the pulley and the rest of the accessories on your serp. belt system.

[GrandAm2000se]

you get like .5-1 for the pulley and like 2-5 for the exhaust....

[The Artist]

you get like .5-1 for the pulley and like 2-5 for the exhaust....

what proof do you have of these numbers?

[GrandAm2000se]

what proof do you have of these numbers?

my vehicle... sh.t does nothing to the vehicle beside looks... i'll get you a dyno slip sometime when i get time to do it, still be at 150ish hp ..

[CalebSE]

This is more of a question than an answer, wouldnt a good exhaust job (upgrade to 2.5 inch pipes) and a new flow through muffler add more than 2-5 HP?

[urweak]

This is more of a question than an answer, wouldnt a good exhaust job (upgrade to 2.5 inch pipes) and a new flow through muffler add more than 2-5 HP?


it all depends, but my quess is still 5-10hp (5 being common, 10 being lucky) Also some peoples estimates might judge it from wheel HP (WHP) as apposed to crank HP (usally just stated as HP).

[98BlackGAGT]

This is more of a question than an answer, wouldnt a good exhaust job (upgrade to 2.5 inch pipes) and a new flow through muffler add more than 2-5 HP?

In theory it should, but in order for it to be fully effective it needs more than just a new catback with a better Catalytic converter... mufflers wont effect horsepower at all (atleast they shouldnt, unless you have no cat and the only backpressure you get at all is from your mufflers) But in order for a catback to be fully effective you need to get the air going into that cat-back better flowing as well, that means from the manifold to the cat (Headers), and the air going into the engine through to the exhaust manifold (cold air intake systems, better intake manifolds and throttle bodies...) So yes a catback exhaust should give you more than 2 - 5 HP but not if its by itself, youll get much more HP when you completely help the air flow from beginning to end... altogether youd be looking at more of a 20 or so HP gain for a setup as simple as a warm or cold air intake, headers and catback... depending on the original engine power... your good for about a 15% gain altogether between everything.

[GrandAm2000se]

In theory it should, but in order for it to be fully effective it needs more than just a new catback with a better Catalytic converter... mufflers wont effect horsepower at all (atleast they shouldnt, unless you have no cat and the only backpressure you get at all is from your mufflers) But in order for a catback to be fully effective you need to get the air going into that cat-back better flowing as well, that means from the manifold to the cat (Headers), and the air going into the engine through to the exhaust manifold (cold air intake systems, better intake manifolds and throttle bodies...) So yes a catback exhaust should give you more than 2 - 5 HP but not if its by itself, youll get much more HP when you completely help the air flow from beginning to end... altogether youd be looking at more of a 20 or so HP gain for a setup as simple as a warm or cold air intake, headers and catback... depending on the original engine power... your good for about a 15% gain altogether between everything.

Yes!, headers are very important to improve your hp from your exhaust... thats why i said you barely get any HP, because its true unless you get the complete system like blackgt was talking about..

[98BlackGAGT]

Yes!, headers are very important to improve your hp from your exhaust... thats why i said you barely get any HP, because its true unless you get the complete system like blackgt was talking about..

I started the same way, my first mods were a w.a.i from bomz (ebay), a bomz lightweight underdrive pulley, and a 2 1/4" borla catback with a smaller cat (not high flow but less restrictive) I added the headers about 2 weeks ago and wow what a difference. There was a noticeable difference before withouth the headers and everything else but the headers made it 100% better. Id say altogether atleast a 20hp difference but thats a guestimate... ill be getting dyno'd in the spring hopefully to show actual proof...

[Matt95GT]

I would stick with 2.25" with an automatic, in effort not to lose too much low-end torque.

There is however some debate on this mod, some feel that the replacment of the balancing pulley for a lightweight pulley will cause engine damage.


My thoughts exactly... I've seen more than a few people have the infamous spun bearing while using an aftermarket underdrive pulley.

If you insist on underdriving, I would suggest the stock HO crank pulley and/or the UR alternator pulley. The stock HO pulley will retain the stock vibration-damping characteristics of the crank pulley.

what proof do you have of these numbers?

I will back that up. When my car was stock or near-stock, I used to frequently remove the serpentine belt to race. (zero-drive pulley? :lol: ) I couldn't find any significant difference with belt on or off. Since the serpentine belt only drives the A/C compressor (which is disengaged during racing anyway) and the alternator, the Quad 4 / Twin Cam simply doesn't benefit from underdriving like cars which also have PS pump and water pump driven by the serpentine belt.

[civickiller18]

hes right about the vibration dampning i wiped out all four of my rod bearings at 82000 miles because of that pulley.

[Starman2001]

I'd avoid the pulley. The 2.4 is a very free-revving little engine anyway. A larger and more free-flowing exhaust might add a tad of power, and cold-air induction might add a few horses also. I fabricated a cold air system for mine using tubing and a K&N round high flow filter. It's very inexpensive and does everything as well as the $275 kits do. Just be sure to keep the tube as SHORT as possible, free of bends and as smooth as possible on the inside. My 2.4 is very fast, very responsive and has taken several of the new G-6's with the V-6. I test drove a G-6 before deciding to just keep my 2001 2.4. The G-6 I drove was a v-6 GT (NOT a GTP) and it was not as fast as my 4.