New JDM engine boosts less than old one

[JohnRardin]

I just did an engine and transmission swap from a 160k mile 7MGTE to a 40k mile JDM engine and I noticed that the new engine only boosts to about 6psi. This is strange because with my old engine, after full 3" exhaust, K&N FIPK, and intercooler piping the boost gauge would max out at 8+psi. My new engine feels stronger than my old one, yet only boosts the stock turbo psi (6).

Anyone have any idea why this might happen? Is there a difference in JDM stock turbo pressure and US stock pressure? Is there a chance that the stock guage isn't working properly?

 

[plaaya69]

Maybe you have a boost leak. Also you can check the vacuume line that goes to the boost pressure sensor to see if it is cracked, loose or needs to be replaced.

 

[johnathan1]

I vote for a boost leak.

 

[theKnifeArtist]

must be a boost leak. 6psi? i keep pegging my boost gauge and i have a stock exhaust and stock ic pipping..
but not for long:evil2:
but yeah, another vote for boost leak

 

[whenmunkysfly]

he did say it runs stronger then his usdm engine so i dont think it would be running best if it was a boost leak. im thinking ether something is in the boost line running to your gauge or your old engine was running so bad that your new engine runs better at lower boost but that doesnt explain the lower boost pressure unless something is going on with your wastegate or something to that effect.

 

[JohnRardin]

Yea, I'm kind of stumped. Most likely, it's a boost leak. I'm concidering trying to shim the wastegate with, say, 2 washers......just to see the difference. How reliable is the stock boost gauge? Are there any factors that could make it inacurate?

 

[plaaya69]

If I were you before you shim the wastegate, I would test for a boost leak.

 

[aye mate]

Test for a boost leak and get a mechanical boost gauge stocker is crap. My stock gauge is about a 1.5 psi off my VDO mechanical and doesn't even start moving until my VDO is around 5psi.

 

[drjonez]

one of the engines had a weaker/less functional WG....

 

[Doward]

Doc's right - I take it you used the turbo on the JDM, right? Sounds to me that the wastegate is stock on the JDM, and the one on the USDM (stocker) had a washer or two that maybe you weren't aware of