I have recently finished my build up, specs in Sig. The car is quick but not as powerful as it should be i dont think. I know part of it is in my exaust. Stock catback with flowmaster muffler. But I also wondered if i would notice big gains by goin to a 52mm or so throttle body. I have heard so many horror stories about not being able to get and aftermarket TB to idle right. Any suggestions are appreciated.

Thanks
Dan

 

It is said that you don't need to upgrade to a bigger TB unless you are making 400 horses. With the set up you have you should be pretty close if not there. The cat-back is definitly part of the problem. From what I've read, most people with A4s shouldn't get larger then a 52mm TB, I'm not sure why though.

 

I have a ported stocker that is 52mm on my car and have no idle problems at all. I noticed a gain with the heads cam also.

You need to open up the intake and exhaust to see the most from each mod

 

Why the hell would you do all of the heads and cam work and not have a catback on there??

 

It's was a budget / time thing. I have an electric cutout sitting in a box waiting to go on next time i get the chance. I would like to have a catback too, but we'll see how far i can stretch the money i have.

FYI: im in college, so its not like i can just go buy anything i want tomorrow.

 

Buy a used Hooker...can probly pick it up for like $150.

 

You can pic up a used hooker for alot less than $150...or so I've heard.

 

Hey bro I know how you feel trying to save cash. If you have a good mufler shop around the will be able to make you a three inch from the orp to the Flowmaster for not too much. Did you get bigger injectors and a tune after the heads? Also did you replace the lifters? There is a guy on here that runs low 12s with heads and a stock tb with af like you have. The stock w/ af will support 400hp so I wouldnt think it would hurt you much. Good luck

 

I added a 58mm TB to my car and it feels more snappy and responsive down low. It may of been holding my power back a little but not enough to really feel like a bottle neck in the car. If you are thinking your car is down on power i would look to the fuel system. After i did my heads and 230/236 my stock fuel pump couldn't keep up and was killing my power. I now have that fixed and love it. I would probably just keep the stock cat back on and put the Cut out right after your Cat or off road pipe. That way you will have a nice quiet car it would also give you a nice sleeper effect. Then when its nice to run it open the cut out. At least that is what i would do if i could do it all over again. Why waste $$$ on a catback when you could just get an E-cutout and have the quietness of a stock exhaust but the free flowing power of the cut out.

 

Yeah I did a lot of the other stuff to go with the heads and cam. SVO 30# injectors, Ractroix pump, and a pcmforless tune. I havnt actually had it on a dyno or to the track yet so i cant confirm it being down on power except for the seat of the pants meter. We are trying to rearange a dyno day so alvin at pcmforless can do some dyno tunes. I was just asking basically if i would see many gains from a TB. I know my exaust has much to be desired, but is it really gonna kill that much power?

 

www.ws6.com showed gains of 10rwhp off a borla on a stock car. The more the car can breathe the more loss in power there is having that stock catback on.

 

mine really woke up when i ported my stock TB/MAF.
do that and toss on a cut-out and i think u should see a fairly good gain in power

 

Just something to keep in mind - a lot of the change people notice after installing a larger TB is that you are actually letting more air in at the same throttle angle (at part throttle, especially just off idle). This creates the illusion of more power. My guess is the trap speed doesn't increase anywhere near as much as you'd expect it to, given the perceived SOTP improvements. You could get this improvement from changing the cam profile that the throttle cable pulls on (to make the blades rotate more per linear motion of the throttle cable). Just something to consider.

 

Plus a bigger throttle body is going to lean out your car and could throw your tune off a bit. IMHO.

I'm in college too buddy, but a catback was my second mod.... Like most people. It just makes sense that way. But yeah, what they said, with an E cutout you should see gains. Most people only see good gains going from stock TB to 58, the gains from stock to 52 are nominal at best. Again, JMHO.



Chris

 

I agree with that most people say you should just jump from 48 to 58mm. I would like to know how a throttlebody can make your car go lean? You still have all your sensors sensing what comes in the motor and what goes out. So i don't see how you can get any lean conditions. Maybe i'm wrong.