sr20det slowly loses boost

[skylinewtp21]

i have a sr20det with an s15 spec r turbo @ 1.4 bar regulated by an hks wastegate, 480cc injectors, and n62 maf. it will hold 1.4 lbs till about 5000 rpm and then will start to drop down to .98 lbs by redline. i have check for boost leaks many times with a boost leak tester and no leaks at all. and i also have no leads before the turbo. so what could also be causing this?

[reccakun08]

probably because the s15 turbo is past efficiency range

[specialk2003]

What are you using for a BOV? Could be leaking.

[NiSilS14]

probably because the s15 turbo is past efficiency range

+1, 20-21psi is a lot for a S15 turbo. Time for a gt2871r.

[smelly240]

yeah - that turbo just cant hold that much boost (even with the wg shut it prolly wont.)

[skylinewtp21]

i know its past its efficiency range but it should be able to hold 18psi since thats what the max of the turbo is and 1.4 lbs was just kind of a test to see if drop was a consistent amount like it would drop to 1.1 instead of .98. so no mater wat boost it drops to .98 this car is usually running on 1.2 lbs.

my friend also has a the same setup as me but his wastegate broke and it was able to hold about 22psi all the way through the rpms. so eventhough the turbo is being maxed out it should be able to hold boost.

and the bov is a tial 50mm wastegate it stays close while the engine is cold but once it warms up it starts to barely open at idle.


also when i have taken the intake side of the turbo off and there is no shaft play on the turbo so there isn't any damage to it.

[DJ_Sunrise]

i know its past its efficiency range but it should be able to hold 18psi since thats what the max of the turbo is and 1.4 lbs was just kind of a test to see if drop was a consistent amount like it would drop to 1.1 instead of .98. so no mater wat boost it drops to .98 this car is usually running on 1.2 lbs.

my friend also has a the same setup as me but his wastegate broke and it was able to hold about 22psi all the way through the rpms. so eventhough the turbo is being maxed out it should be able to hold boost.

and the bov is a tial 50mm wastegate it stays close while the engine is cold but once it warms up it starts to barely open at idle.


also when i have taken the intake side of the turbo off and there is no shaft play on the turbo so there isn't any damage to it.

Ok, well 1st thing is I think you mean BAR, as my car builds 1.5 lbs of boost at startup while cranking. If you don't use the right terminology, people are going to have a hard time understanding you:p. 14.7 lbs. per square inch= 1 Bar.

2nd.. so you are using a tial waste gate as a BOV? HUH? :l101:

Repost what you are trying to say, as its difficult to understand.

Get a vacuum pump at harbor freight.. There are no name brand differences.. mity vac is the company you'll find at Harbor freight, Sears, Pep boys, etc. There are other more exotic pumps, but this does the trick.

Hook the vacuum pump up to the waste gate, and pay attention to what happens. You should be able to figure the rest out.

Do yourself a favor, and buy a Forge Unos manual boost controller. It is the hardest hitting boost controller on the market, probably the only one that keeps the wastegate shut 100% till the boost setting is reached. I found that just a wastegate setup wasn't enough to control my cars boost properly.

-Bart

[skylinewtp21]

sorry about that im horrible with words :duh: but i will try what you said. thanks for the help

[chituntang]

You have ebc? If there's no leaks, maybe your car just ran out of breath.

[slider2828]

So retarded.... Your exhaust flow isn't pushing much more than the turbine can compress, so of course you going to get drop off nub....

Hence you reached and went past the efficiency level of the turbo for your motor....

Get off already.... if you want, you spend more money on the Greddy E01 boost controller and work with the RPM Offset for the boost levels.... Otherwise too bad, get a bigger turbo or live with it....

Secondly efficiency DOES NOT MEAN it holds 18psi all through the rev range either....

[S13 curtis]

I<3 Tech section. lol