Hey guys, I was cruising in my 88 TII running at 10 psi with a friend tonight. We were going pretty hard.



It has:

s5 motor/turbo swapped

racing beat downpipe with pre-silencer

mazdaspeed exhaust

cone air filter (aftermarket: "Intimidator" or something..... not that fancy anyhow)

ported wastgate

running 94 octane gasoline (tank about 1/4 left)

Engine completly warmed up, stable temp.



I was in 4th gear at 10psi full throttle, foot to the floor.

At about 5000 rpm my boost started to drop (decrease, while still flooring) to like 5 or 4 psi, so i let go off the gas, and took it easy on the way home. Dont know if it would have dropped further more if I continured flooring it.



Still a turbo newby here....



what might be causing this?



Thanks.

 

dude its like 5 am on saturday morning.

and on that note im sorry to say that there is absolutely nothing that i can do for you in this case, the fact that i have no fukin idea whats wrong with your car plays a big role along with it being 7 am and i just woke up., im sure someone here will have your answer though

 

It's bleeding off, the stock exhaust housing is too small to flow that much air at those rpm's, it's normal. Specially with the ported WG, I know when I had a non ported WG it would hold 11psi to redline in 4th.

 

yeah the boost drops off like that up top

 

yea, i think you should just get rid of the boost and solve your problem

 

So I was under the impression it was bad, but I guess its a normal thing? So to maintain a constant boost around those RPM at that gear would be bad or better with a bigger exhaust housing?

Thanks for the replies.





get rid of the boost? haha what are you talking about?

 

yeah basically you need a larger turbo

 

Would be interesting to swap JUST a P trim into a stock turbo...

 

you know do a turbo -> na conversion and your problems will be solved, if you really want ill even take the turbo off of your hands

 

LOL once you go turbo you cant go back :P