Flowmasters and Backpressure BS

[ccapehartusarmyINF.(ret)]

anyother day id jump right in and get start a pissing contest but im in a good mood
so you believe what you believe and i guess im officially dumber

 

[Wake]

Back pressure or exhaust restriction, is a funny thing. It does effect two things for sure, power band/response and overall HP. Corking down exhaust actually helps or makes low rpm power feel more responsive, and that comes at the expense of top end power and overall HP. All this with a million variables but generally the bigger or less restrictive the exhaust, the higher the powerband comes in. Intake manifolds seem to react similarly. I've installed 3 different header sizes on my Camaro, 1 5/8 hedman, 1 3/4 LPP, and 1 7/8 ******, and each change was met with less low end and midrange power, and a kick in the ass above 5k. For street driving, the 1 5/8ths had the most usable power and felt the most torquey. Same goes for muffler restriction within reason but less noticeable.

Yup, and why a lot of performance autos are now offering dual mode exhaust systems from the factory. Keep the backpressure at lower RPMs and bypass the muffler at higher RPM where you need more free-breathing.

I'd like to see the OP's dyno run if he has one of a large exhaust system on an otherwise stock engine. I'd be shocked if there wasn't noticeable torque loss at the lower end.

I'm relatively new on the truck/SUV side of the forums. Up until a few years ago I never dreamed I'd own an SUV. I'm still constantly surprised at how many people modify their trucks for max high end horsepower, seems to me counter intuitive. I can see doing it on a lighter sports car where you spend much more time at higher RPM and spare torque on the low end, but in a heavy truck where you'd want the low end torque to get it moving, it seems the opposite way to go for me.

I had a tune done on my first SUV, an I6 powered Trailblazer. When requesting the tune I asked for the towing tune since I don't treat it like a race car. I was very happy with the shift in torque to the low end (thanks VVT technology) and I definitely felt the compromise at the top end the few times I pushed it hard to 6K rpm. At the end of the day though the truck spent 99% of it's life in the 1500 - 3000 RPM range, that was exactly where my towing (versus racing) tune made much more sense to me.

 

[JKmotorsports]

I'm relatively new on the truck/SUV side of the forums. Up until a few years ago I never dreamed I'd own an SUV. I'm still constantly surprised at how many people modify their trucks for max high end horsepower, seems to me counter intuitive.

Before buying my first SUV, I felt the way you did. But after owning, building, and racing several camaros, trans ams, etc, I wanted to try something different. It's a bit more challenging and rewarding when you're spanking vettes, mustangs, etc with a 5500+ lb full sized SUV. And seeing the facial expression from some of these sports car owners afterwards is priceless. People can understand losing to a high HP coupe or sedan, but not a daily driven, grocery getting Tahoe that is still easily capable of towing.

 

[Big Buttons]

Before buying my first SUV, I felt the way you did. But after owning, building, and racing several camaros, trans ams, etc, I wanted to try something different. It's a bit more challenging and rewarding when you're spanking vettes, mustangs, etc with a 5500+ lb full sized SUV. And seeing the facial expression from some of these sports car owners afterwards is priceless. People can understand losing to a high HP coupe or sedan, but not a daily driven, grocery getting Tahoe that is still easily capable of towing.

This but mine burb weighs more lol

 

[JennaBear]

This, but mine has a bigger engine

 

[Pachanga02]

This, but I wish I was fast
Just to keep it going.

 

[07Burb]

...oh and good to see JKMotorsports posting up!!

 

[Goodinblack]

This.

I wish I had a blown 6.2

 

[JennaBear]

What guy doesn't want to be blown? Or stroked for that matter

 

[Pockets]

What guy doesn't want to be blown? Or stroked for that matter

Lee wants to be injected. [emoji15]