Do you lose boost with headers?
You will show less boost, but you didn't loose it lol! You are still pushing the same amount of air from the S/C. You should make a little more power and it will show less boost due to the fact that you are getting the air out faster. Should you put a smaller pulley to keep x amount of pounds of boost, well not really unless you are just trying to make more power cause if you put a smaller pulley on you will be moving more air and you will make more power if you have the fuel to do so etc... All am saying is don't pay attention to the boost you are making focus your power out put as a final factor. IE: do you want or need more, can your car handle it reliably, do you have enough fuel for the added air/Boost etc... Good luck have fun go faster LOL!
Jeff
Jeff
As Jeff mentioned, you will show a loss of boost. If you don't check your air/fuel ratio and you drop to a smaller pulley after you add headers, you stand the chance of hurting your engine. We shoot for 7-8 psi of boost with stock LS2 engines with headers and exhaust. Here is one to check out.
http://www.exoticperformanceplus.com...Car.php?car=46 Bob
http://www.exoticperformanceplus.com...Car.php?car=46 Bob
Remember boost is a measurement of restriction, not performance. With the same pulley on, you will see less boost because the headers will allow the exhaust gases to get expelled more easily allowing more air to enter the cylinder. Boost numbers only playing an important part in dyno racing 
Keith
Keith
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Thanks guys,
Good explaination. I guess the question now is do I go to a smaller pulley. Or take advantage of less intake temps and driveline loss. I like going road racing so I may just try it with less boost.
Would a cam or heads be more beneficial next?
Good explaination. I guess the question now is do I go to a smaller pulley. Or take advantage of less intake temps and driveline loss. I like going road racing so I may just try it with less boost.
Would a cam or heads be more beneficial next?
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Not as much as you might think, I would say about 20hp or so at least it is what we saw on a car when we went from stock to headers and ORY and about a 2lb drop on the boost gauge. Good luck!
Jeff
Jeff
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Verdad Gallardo Thread Starter
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Jeff thank you,
Do you think I should do the 3.8" Pulley instead of the 4" I have right now?
Will I be increasing my intake temps a lot more?
If you are not out of the effective range of that S/C I am guessing a P1sc then it shouldn't be a huge issue. And you haven't said what vehicle this is on that makes a difference as the designes are different on the intercoolers, but if you are using the stock ATI set up you would benifit from installing a methanol kit such as my favorite one made by Snow Performance. And at that point intake temp will drop, but you will have to get it tuned just as if you change the pulley etc... Good luck!
Jeff
Jeff
I just posted the same question in the truck section:
"I installed headers last fall, and today I was going over the one scan that I did afterwards. It seems that boost dropped from 11-12 psi to 7psi.
Doesn't that seem excessive?"
What do you guys think?
"I installed headers last fall, and today I was going over the one scan that I did afterwards. It seems that boost dropped from 11-12 psi to 7psi.
Doesn't that seem excessive?"
What do you guys think?
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As Jeff mentioned, you will show a loss of boost. If you don't check your air/fuel ratio and you drop to a smaller pulley after you add headers, you stand the chance of hurting your engine. We shoot for 7-8 psi of boost with stock LS2 engines with headers and exhaust. Here is one to check out.
http://www.exoticperformanceplus.com...Car.php?car=46 Bob
http://www.exoticperformanceplus.com...Car.php?car=46 Bob
