low boost with different combo

[tom j]

replaced engine with one with p&p heads cam and all the same parts with same combo, i could easily run 28 lbs of boost on old motor, now with actuator all the way in only 19 lbs of boost, like I said only the long block was changed everything else is the same, pt51, stock actuator, What would you guys check first

 

[rpk250]

That's what a good set of heads will do. The engines probably just flowing air alot better. Is your car slower now at 19lbs of boost than it was at 28lb? Might be time for bigger turbo/convertor.

 

[tom j]

the car went the same speed, with the new motor, but 9lbs less boost, what can i do to increase boost, do you think there is something wrong with the wastegate, I figured it would go just as fast with less boost, but I CANT TURN IT UP! I have seen guys with bigger turbos and stock actuators run near 30 lbs of boost with heads , what would you guys dive into first, i just dont want just start changing parts turbos, actuators, ect..

 

[BLACK6PACK]

How fast is it going? The 51 may be done where you're at. Boost is nothing but a build up of air behind the intake valves. If the heads and cam are flowing big time, the turbo can't spit out enough air to make more than 19 lbs of boost.

 

[tom j]

116 mph, is there a way to test this out,

 

[tom j]

112 mph my mistake

 

[chris2316]

this happens alot you turbo is probably tweaked out , it can no longer create enough pressure , hence bigger turbo .

 

[tom j]

is there a way to check the wastgate seliniod

 

[Louie L.]

is there a way to check the wastgate seliniod

Yes you can use a vaccum tool to check the internal diaphram for leaks.

An easier test would be to wire the wastegate arm shut with a wire hanger and go make a pass. If it goes to over 19 psi there is your problem. Must have good race gas for this test. Make sure that you are paying close attention to the boost gauge and get out of the throttle if its going to shoot over 23-25 psi.

That turbo should go faster than 112 with a ported head motor. You must also look at other things that may be causeing a slow down. But first we must eliminate the above.

 

[49-blues]

What size converter is in the car? maybe what you need to change.

 

[tom j]

3000 stall, it shuold be going alot faster

 

[trading t/a]

try a grainger valve it'll let you bleed off some of the pressure gradually rather than letting the boost spike to the moon. If you're using a stock wg the diaphram spring may not be able to hold it. Just something to think about...

 

[tom j]

i wired the gate closed and there was no change only got 19lbs of boost do you guys think the turbo has gone south, only other thing is maybe the puck isnt sealling, thdp i will check this weekend for alignment, but i have a feelling that is not it, no exhaust leaks, even if there were leaks wouldnt it still change after i wired the gate closed? just a thought, NOT HAPPY

 

[tom j]

ttt