blownroush

Is it true that 1" 3/4 headers and full exhaust will cost you boost on a supercharged motor? My car has a Vortech kit and before the exhaust it was tuned to 415rwhp now after the exhaust it dropped to 409rwhp an dropped 10 pounds of tourque. Should I go to a smaller pulleynow if true to bring the boost up?

cheftjpeck

your torque curve should have increased.....something does not sound right....also...take into account the dyno factors....when did you have it dynoed before....did you dyno the same place...what was the temp difference...I mean it is summer after all right now....smaller pulley will increase your boost...but what is the rest of your setup.....dont let numbers worry you too much,....the most important is how does it feel to you...but I would looka t all of the factors I mentioned....good luck..

drbobvs

Different day, different numbers, that's all. Also possible is some belt slippage due to stretch over time.

KB has said, time and time again, that our stock exhaust does not become a restriction tilover 500 rwhp, so I'm not surprised at the numbers anyway.

BTW, anyone see the latest MM&FF article where they bolted on a Stainless Works full 3" exhaust w/ headers and gained like 2hp?

marcuskeeler

No, the boost pressure won't be affected by anything after [closed] exhaust valves. What the car does with the boost after that could well be affected by the headers although frankly, a difference of +/- 10hp is nothing, as previously said, different day, different temps, different gas blah blah blah

mygt500

1+. Your car is breathing better and be content with that on your S/C'd stang! To be quite honest our shorty headers do a get job from the factory until higher HP application. Link for some reading..http://www.alternativeauto.com/water...texhaustupdatescroll down to aug 24,2005 and toward the end of that update it explains things a little better.

blownroush

Well cheftjpeck I had it dynoed at the same place. The temp was in the 90s this time. The problem is when I put the exhaust on with the 1st tune it felt like it had more power. Low end definately had more before the second tune. I just dont know if it was a good tune before but there was no pinging or detonation. I am thinking of putting that one back in. My set up is mac long tubes catted prochamber 4.10s and a vortech non cooled blower. The torque curve dropped the most. If I just add a 1 size smaller pulley would I be able to adjust the tune myself? I dont want to spend anymore money on dynos. What do you guys think?

ratnacage

Spend money on dyno tuning or spend it on broken engine parts - your choice. Seriously, you've probably invested several thousands (minimum)on parts. A few hundred more on proper tuning is nothing.

hammeron

if your already at 5 - 7psi, you probably shouldn't
go any higher until you install an intercooling system.

mygt500

1+ Intercooler!

jerjan

If you changed the tune after the first dyno, you gotta expect different results, There are so many variables, especiall temperature and humidity,best thing you could do is get it dyno'd again with the new changes you've made. Also, when you make changes like that, it's not uncommon to show lower boost pressure on a gauge, that does not mean you will have less performance, it means you have relieved backpressure and your motor is breathing better. Putting onLTs and a free flowing exhaust can change alot of things, Chances are you are flowing more air through the motor and your A/F mixture is off, get it dyno'd, your shop should be able to write a new tune for you that will produce more power than you had before.