Engine not building boost until 6k... (yes I've done a boost leak test & much more!

[forcefed86]

Trying to help a friend out with his car. Basic problem is we build around 5psi at 5k and 14ish by 7800. Started out with a 16g, just installed a garret 57mm turbo today w/ new external WG. No change.

Basic run down:
6 bolt motor
Unknown mileage on forged internals.
Just replaced head gasket.
272 BC cams (installed straight up factory gears.)
garret 57mm t3 turbo .70 ar (wastegateless)
New t3 OBX manifold, no leaks or cracks (yet anyway)
external gate
3" downpipe no exhaust

No boost leaks.

Compression tested 150-155 on all 4 cyl. (not a leak down tester)

Good oil pressures.

Tuning with jakal SD. AFR's in check mid 11's in boost 14's cruise.

Factory BOV

Have tried blocking WG off completely, no change in boost press.
Completely blocked off BOV ( no change)
No coolant in oil or VS versa.

I'm out of ideas! Could cam timing be off enough to cause this? I'd assume we would be crashing into valves if timing was off that much. After a brief 1st gear wot and a solid 2 min of idling we popped the hood and the turbo was glowing slightly. Seems to point back to the timing being off... I didn't install the head gasket so I'm not sure any of this is done correctly. Car seems to drive and idle normally. Timing at idle is 12* running a 2g timing map.

I'm stumped...

 

[banishedmunk]

Does the car have a stock catalytic converter?

 

[forcefed86]

Does the car have a stock catalytic converter?

Sorry, I updated the first post. Running an open 3" DP. No cat

 

[gofer]

Is there a flex section in the downpipe?

 

[kris_stewart10]

What about shaft play? Try using more fuel in this situation its a very very rare problem even with boost leak i still built boost at 4k-4.5k . What pump are you using maybe not enough fuel to compensate for the boost. How about a vaccum leak? im running through troubleshooting. Maybe not having an exhaust on there is affecting the exhaust gases going around the hot side of the turbo. someone please correct me if i am wrong.

 

[forcefed86]

What about shaft play? Try using more fuel in this situation its a very very rare problem even with boost leak i still built boost at 4k-4.5k . What pump are you using maybe not enough fuel to compensate for the boost. How about a vaccum leak? im running through troubleshooting. Maybe not having an exhaust on there is affecting the exhaust gases going around the hot side of the turbo. someone please correct me if i am wrong.

Turbo is new no shaft play.

More or less fuel won't stop a turbo from building boost. As stated fuel is in the proper AFR range.

Walbro 255HP good pressure etc. Again this wouldn't cause a turbo not to build boost.

Having an open down pipe will not affect exh gas going through the turbo that is post turbo.

Thanks though...

 

[gofer]

...and I repeat, is there a flex section on the downpipe?

 

[forcefed86]

...and I repeat, is there a flex section on the downpipe?

negative. down pipe is literally a mandrel bent 3" 90 and 10" if straight 3" pipe.

 

[Chrispy0530]

I had this same exact problem. It turned out to be the flapper on the exhaust side to be wide open.

2 things that can solve this if this is your problem. Weld the wastegate in the shut position, or weld a disc over the waste gate door.

Trust me, it's no fun driving like that, and I drove like that for about 6 months.


edit: Actually, I missed the part where you said you swapped to a garret 57mm turbo. Thought you were still on the 16g. Not too familiar with those if they have internal waste gates or not. Either way, the boost IS escaping from somewhere if the turbo is in perfect condition.

 

[forcefed86]

I had this same exact problem. It turned out to be the flapper on the exhaust side to be wide open.

2 things that can solve this if this is your problem. Weld the wastegate in the shut position, or weld a disc over the waste gate door.

Trust me, it's no fun driving like that, and I drove like that for about 6 months.


edit: Actually, I missed the part where you said you swapped to a garret 57mm turbo. Thought you were still on the 16g. Not too familiar with those if they have internal waste gates or not. Either way, the boost IS escaping from somewhere if the turbo is in perfect condition.

garrett housing has no wg. flanges are new no exhaust leaks with gate blocked off it made no difference. has to be leaking internally. Just not sure how since tbe comp test is good.

 

[banishedmunk]

Just to throw it out there, have you done a boost leak test on just the intercooler?

is the fire ring in the external wastegate?

 

[AllShallPerish]

After a brief 1st gear wot and a solid 2 min of idling we popped the hood and the turbo was glowing slightly. :

This indicates a timing issue. Go over everything again and make sure the timing belt is not worn out or stretched.

Just noticed this was a month old... Did you ever figure this out? :O