what is catback exhaust

[Kven]

Originally Posted by bjdm151

Oh, and Kven
Stop wasting your money on sea foam and octane booster

its fun wasting money, lol. actually the sea foam helped my engine run a little better(stopped some of the smoke that came out my exhaust); i ran it through a vacuum line straight into the intake. as far as power goes, it doesnt really help. as for the octane booster; i buy it just because its available

[CBFryman]

Originally Posted by Kven

no shit? then why didnt you explain that before?

because most of the time i dont state the obvious...

[Kven]

Originally Posted by CBFryman

yes i know a turbo is a supercharger, and even 3" pipe is quite large, but why wouldnt you want the largest pip possible for an NA engine?

yes, quite obvious.

[RandomTask]

Originally Posted by Kven

youre talking about the exhaust manifold. after the turbo its better to run larger piping to reduce any pressure on the turbine exhaust side. just thought i might add that.

I agree

[RandomTask]

Tuning an exhaust requires some hellish fluid dynamics. We had to do it for our formula SAE car and it was EXTREMELY time consuming.

[CBFryman]

Originally Posted by Kven

yes, quite obvious.

after not noteing sarcasum....

[bjdm151]

Tuning an exhaust is actually not that hard. I don't have the formulas with me, and i'm to lazy to dig through my old notes, but you're pretty much looking at rpm range cylinder size, header length and diamater, collector length and diamater, and exhaust length and diamater. If you have access to a dyno and you have the parts nescessarry you can actually see some horspower gains. I've done this once where we actually calculated collector length and gained aprox 5hp on a chevy 350 just by shortening the collector 3". I've also done some exhaust testing on formula vees where we were just testing exhaust before a race weekend and gained 2hp. this doesn't sound like much, but when the motors you and you're competition are using only make about 50 hp to the wheels it can mean the world. The greatest thing was the long, flat curves we saw on the dyno.
You might not be thinking that gaining 5 HP is any big deal, but just think of how much money a nascar team is putting into development to gain just a single hp, or even get the correct hp/torque curves for a specific track. Exhaust tuning is a big part of their game.

[RandomTask]

No, I agree, we used fluid dynamics to help us creating the bends and what not. I do agree. You sound familiar with the SAE scene, perhaps you participate? We ended up with 76hp and 47fl/lbs of torque last year off of our suzuki 600gsxr. You're mentioning nascar, think about formula one. They're putting out 1000+ HP out of 3.0L motors that wind up to 20k rpm...

[bjdm151]

I understand what you are saying now, using fluid dynamics to use the bends. Not in formula SAE, tried to get the school interested, but they were already getting a baja program off the ground. Besides, there are a few things i don't like about formula SAE. I just used nascar because most people can understand short/long track, and restrictor plates. trust me i know f1 is way more technical in every aspect than nascar. I've recently been trying to stay up ( usually doesn't work) to watch the a.m. races on speed. I can't imagine the craziness that will occur if they switch to 2.4 eights. Supposadly they will have them spinning at 24k rpm. I don't get it. They say they want to make it safer/cheaper, but their safety record is almost impecable compared to many other events and i don't think increasing the rpm of a time bomb that goes off after 500km will be any safer. And changing engine packages will only make it more expensive for the smaller teams.