WHY CAN'T I HOLD 15 PSI?!? Another dissatisfied, jaded KA-T owner.

[WDRacing]

Non intercooled doesn't make you over heat or make you lose compression. Drag cars run with no IC all the time. Improper tuning leads to the detonation that can cause cracked rings or ring lands which will lead to a drop in compression. Also, a non intercooled setup will have less lag then with a IC.

And KA's don't have sleeves.

Think before you post.

[BryanGrigsby]

"I'm in North Carolina the 27th and am working up until them."

MarkEMark,

Not to whore your thread OR make light of your situation with you boost problem, but where in NC are you going to school? Im about an hour from alot of universities in the area and if you need any garage space or tools I'd be willing to help out (also went to school here).

I've looked at your website, its pretty dope. I just bought a 98, I'd love to get some of your insight on some things!

[turbo_lover]

Non intercooled doesn't make you over heat or make you lose compression. Drag cars run with no IC all the time. Improper tuning leads to the detonation that can cause cracked rings or ring lands which will lead to a drop in compression. Also, a non intercooled setup will have less lag then with a IC.

And KA's don't have sleeves.

Think before you post.

Non intercooled doesn't make you over heat or make you lose compression. Drag cars run with no IC all the time. Improper tuning leads to the detonation that can cause cracked rings or ring lands which will lead to a drop in compression. Also, a non intercooled setup will have less lag then with a IC.

And KA's don't have sleeves.

Think before you post.

sorry if this is off topic or anything... but don't they have a special 'coating' in the cylinders like (for EX:) the h23 from honda or is it different ?

[erich]

It's your wastgate actuator.If it opens at 14 PSI then it is about a 7 PSI wasegate.What you are neglecting it the exhaust pressure pushing on the flapper valve trying to force the wastegate open. The exhaust pressure plus the boost signal will open the wastegte much earlier then with just the boost signal by itself.If the actuator is adjustable you should tighten it down a litte bit and see if it makes a difference.Eric

[MarkEmark]

It's your wastgate actuator.If it opens at 14 PSI then it is about a 7 PSI wasegate.What you are neglecting it the exhaust pressure pushing on the flapper valve trying to force the wastegate open. The exhaust pressure plus the boost signal will open the wastegte much earlier then with just the boost signal by itself.If the actuator is adjustable you should tighten it down a litte bit and see if it makes a difference.Eric

I had thought about this too, but then I thought that if this were happening to me, then the same scenario would be happening to a lot of other turbocharged cars that use internal wastegates (ie, factory turbocharged cars that are running more boost). Do you think the increased exhaust pressure is from running too small (.48 a/r) turbine? Would running a larger turbo, ie, with a .63 a/r turbine help?

The actuatory is brand new and adjustable, and it's adjusted to maximum boost (shortest length) right now. The thing is, I can adjust the wastegate to 7 psi, but then it'll drop to 5 psi, I can adjust the wastegate to 10 psi, but then it'll drop to 5 psi...and if I use a MBC and hit a maximum of 15 psi, the boost will drop right back down to 7-9 psi.

BryanGrigsby--I'll be in Chapel Hill. Unfortunately, the car will be not. I have on-campus housing

[MarkEmark]

I just installed a pressure gauge at the end of the EGR tube to see if any boost were leaking through it...it's not, as suspected. If any air is escaping through the EGR, it has to escape through this tube, and it's not.

Also, I installed a simple pull-spring along with the wastegate actuator...and it gave me 4 more psi of pressure. Still drops, but it feels decent. Right now it hits 14 psi, drops to 9-10 psi. Feels pretty damn fast, and this is in 95 degree humid-as-hell weather with a passenger. I could only imagine what it feels like with 15 psi everywhere. Even though I am losing 5 psi through the rev-range, the engine still feels pretty strong up top even though it is losing boost up top...I attribute this to the higher lift cams, 3 angle competition valve job, new valve train, and oversized intake/exhaust valves.

Anyway, basically now I'm almost positive it's the turbo....just too damn small. No money or time to upgrade it though. A damn shame. Guess I'll need to wait till christmas or something, when it's soooo nice and cold and the roads are covered with debilitating sand and salt.

[C-Kwik]

I'm stumped...I thought the fact that I got 15 psi up to redline by carefully regulating throttle input ruled out the turbo not being able to build boost....but it HAS to be something with the turbo.

These are the specs for my cams:

Intake 221 duration @.050” .379 lift; (272 advertised duration), .380 lift; Exhaust 231 duration @ .050" lift, (278 advertised duration), .390 lift.

These are the specs for the PDM stage II DOHC TURBO cams. They seem to have very similar specs, minus the duration, of course. But could that much more duration cause the described symptoms.

STAGE II DOHC Turbo Cams – Intake 221 duration @.050”, .380 lift Exhaust 221 duration @.050” .380 lift

Basically, they're identical to my cams except that mine have 10 degrees more overlap on the exhaust cam. Would 10 degrees more overlap cause an instant 5 psi loss like that? Perhaps?

Couple of things. Modultating the throttle to build the boost to 15 psi at the turbo doesn't prove anything. Building 15 psi there is not hard under part throttle conditions. Keep in mind that with the throttle partially open, there is simple less airflow. In order to build more boost, for a given set of conditions, you need more airflow. If you are at WOT, you need to flow more air to build 15 psi at the compressor than at 50% throttle. To do this, the turbo needs to work harder. Also, if there is a leak in the system, it would not be apparent here. Since a turbo compresses the air internally, it will read whatever pressure the air is at as it leaves the turbo. If there is a leak later down the plumbing, it will show the pressure drop at the leak.

The overlap in the cams could be an issue, but I doubt it would get to 15 psi then drop down rapidly. It would simply struggle to boost the right amount entirely.

My thoughts are it is something that shows itself at higher pressures. Kind of like a valve that opens and allows a leak once a certain pressure is reached. I really think it sounds like a hose coupling.

Adding onto a previous question, at what points did you cap off the piping to pressure test it?