Stock engine bay 17-18psi!?!!!

[ericem]

lol I thought my 92 wagon I picked up was brutally fast. So decided to plug in my laptop. Guess what hits 18psi!!!!!!!!!!!!!!!!! WTF isn't it touching fuel cut though? Sometimes it will cut out but takes a couple seconds literally. What could cause this issue with the boost creeping more then double what it should? It looks to be all stock, all I notice is a HKS type 1 turbo timer. Otherwise all stock to me. Under the engine bay has all stock BCS and wiring. Any idea's wtf is up?!

It must lean like insane when it hits 18psi on stock injectors. Not sure how it is moving actually. Must just dump fuel.

[Mattheww044]

wow, I've never heard of that. Thats absolutely crazy. My buddy jordan and I hit 16psi in his SS and just about crapped our pants, and immediately turned down the MBC. I didn't think the injectors, turbo, or fuel pump were even good for 18 psi. Wierd that fuel cut didnt hit either lol... Sorry for no answer though... Best of luck!

[ericem]

ya i exactly shouldnt fuel cut be instant and i am reading psi with my laptop using cable and revtronix btw. Must be dumping fuel. I hope atleast.

[magicmike]

I have been running 15 psi daily with my stock fuel system and have not encountered knock or detonation any other signs of a problem. Its not to say that this is ok but I have no problems and the car pulls like a mofo with my vf34. I actually was running it around 18 psi for a while but turned it back down since I wasn't 100% sure that I was getting enough fuel. but, even at the 18 psi I had no signs of a problem.

[555BCTurbo]

Yeah...18psi on a VF11 = bad

[ericem]

found the problem hose was undone connected it all good. Wot still seems pretty good.

[93forestpearl]

Considering how a centrifugal compressor actually works, higher pressure ratios do very little in terms of airflow when the compressor has reached choke flow. No amount of boost will increase the airflow, no matter what the motor setup is. Compressors flow a finite amount of air, period.

[macipusy]

Also, it is normal for the fuel cut to take 2-3 seconds to kick in. I know a couple of people who run 15 psi on a td04 with not FCD....they just stay in full boost for less then 3 seconds....nothing I would recommend doing.

[BSOD2600]

Also, it is normal for the fuel cut to take 2-3 seconds to kick in.

Yup, thats normal. Under normal circumstances, the BCS would have time to correct the overboost by that ~3 second window... and then since the ECU assumes it cannot, something must be malfunctioning and time to go into safe mode (aka fuel cut).

[tturnpaw]

Considering how a centrifugal compressor actually works, higher pressure ratios do very little in terms of airflow when the compressor has reached choke flow. No amount of boost will increase the airflow, no matter what the motor setup is. Compressors flow a finite amount of air, period.

DING DING DING! We have a winner.


Just a thought, but I wouldnt go over 12-13psi on our stock turbos repetitively.

[georryan]

I forget the efficiency range of the vf-11 turbo, but 18 psi is way outside of that. I think the recommended was not to go over 13.

Like Mike I've run my vf8 turbo up to 17 psi without issues (I have a chip to remove the fuel cut).

I've since lowered my boost to 14 due to some slight issues occasionally after stroking the engine. I'm not sure where the limit is at so I've backed it down to be safe.