Please help me out, I am out of ideas!!!!!

[MrZook]

Okay, here is my setup: Keep in mind i started this turbo kit with $900 in my pocket over a year ago.

Fully built bottom end w/Arias stock bore pistonsK1 forged rodsArp head and rod boltsCometic head gasketCustom indercooler pipingFMICHKS wastegate actuator w/ a 12 pound spring (comes in it from factory)Greddy type S BOVGarrett t25 from a redtop sr20bottom mount equal length turbo manifold.3'' turbo back exhaust w/ a 3'' cutoutWalbro 255 fuel pumpNismo 740cc injectorsEFI specialist tuneZ32 mafZ32 fuel filterAMS FPRand a mouthfull of other parts not worth mentioning

Now here is my issue, I cannot hold boost over 11 psi... ever. I mean by hold i mean after you mashed down the gas for more than a few seconds. I have changed the wastegate, the BOV, and done a pressure test to oversee any boost leaks. I have tried the turbosmart boost controller with no luck. AND rebuilt the turbo. Everytime it spikes around 15 (wich is at the edge of the t25's efficiency range anyways) and regulates back down to 11. Everytime, i have adjusted the wastegate and used a BC. I am totally out of ideas on wich it could be accept just a worn out pos t25. Even still it should never go below 12. I could make serious power if i could just get my hands on a decently sized turbo like a gt3071r or a gt3583r the two i really want. I have no idea what could be possibly holding me back. I have tested time a time again for boost leaks and i thought it was origannly my cheap ebay bov opening up after 11psi. Well i just got a greddy from a friend and no affect. The HKS wastegate actuator should never regulate below 12psi because that is the spring is set at at the factory. My only option now is just to stop messing around with this crappy turbo and invest into something serious is my only option. I wish i could just swap with another t25 and see. I have even plummed water into it. No effect what so ever to see maybe it was heat causing it. So please if anyone has been or knows what im going through please help me out. thankyou

[480sx]

Where do you have your wastegate vac sourced?

If it is connected to the turbo's compressor housing as many turbos are, you will see up to a 1-2 psi difference between your turbo's output and the boost that see's the intake manifold. You will get a pressure drop as the air cools down and travels through the IC.

That being said, a t25 doesnt really make much more than 14-15 psi, and its a heat pump at those higher levels.

With as much money as you'v spent on the t25, the new wastegate ect, you could have bought yourself atleast a mint shaft driven t28 and been set.

[red240ne]

I don't know what to tell you besides get rid of the T25. It sounds like you've covered all of your grounds for boost leaks...Really there isn't much of a difference with a T25 between 12 psi and 15psi on a KA anyways. Around 15psi at T25 is just a heat pump on a KA.

[MrZook]

yeah i know, but recourses are tight and I have just been trying to cover all other problems. I bought the turbo blown over a year ago and rebuilt it myself for under 150 bucks. And the wastegate was 100. But thats what it takes to diagnose a problem sometimes. The car is running so im happy about that. My crave for more power is just a little anoying tick behind my ear. But the (boost source) not vac source for my wastegate is directly on my FMIC piping about 6 inches past the outlet for the turbo. My line is only about 10 inches long or less.

[WDRacing]

Take all the boost and vac signals from the same spot, so everything is seeing the same thing. Use the FPR line on the intake mani. Don't use IC pipe for vac. I don't even use the turbo compressor...

There isn't a problem, the turbo is maxed out. If you want to verify, simply remove the vac line from the wastegate and give it a drive, the wastegate should stay closed.

WD

[MrZook]

i have done that too. It spiked 18psi and i didnt want to hold the throttle mashed down and risk blowing it a 3rd time lol. I use my FPR line for my BOV and boost gauge and thats it. And having the boost line for your wastegate is a bad idea. Having your line that long will cause a chance for creep and spiking. You want it as short as possible thats why people so often tap into the turbo so its only about 4 inches or less. But either way im pretty fed up with this bs. Telling people im fully built and having a weeny of a turbo on it and getting beat from pos stage 2 srt's. My engine and fuel setup could handle 500whp with not to much problem.

So wich t3 flange exhaust mani do you guys think is the best for what im looking for? I was looking at the full-race and the xcessive exhaust mani. But i just question the dp that xcessive uses. I think with no breaks on it it would be almost impossible to fit in and out and it looks like the bend is to shallow to clear the body. i had to modify my SR dp that im using now because of that same reason. I am probably going to go with the GT3583R. The .63 and .83 would probably only be about a few hundredths of a RPM in spool diference, but the comparison is around 20whp on the same boost setting. Pretty mynute imo considering the gain, same price too. My new setup i didnt want to go to much higher than 3g for the mani, turbo, dp and wastegate. Everything else is set up to handle much more than 500whp. The way i intended it to be so i can grow on the engine.

[MrZook]

bump plz, could someone help me out? maybe someone that curently has experience with those manifolds

[480sx]

Those manifolds are made well. Either would be fine, they are both expensive though. You cant tell if the downpipe is going to fit by looking at a picture of it dude. If they make it, charge that much for it, and have been in business this long with multiple local success stories then it most likely fits. I would personally go with full race however, they are an unbelievably skilled shop with world class fabricators. I went with AMS's manifold, however its probably never goin to get made again lol. We needed a 5 person deposit to get them to even make it again.

You have to use a 8mm(or 10? cant remember) vac line for your wastegate. Its probably just for external wastegates actually.

[MrZook]

Those manifolds are made well. Either would be fine, they are both expensive though. You cant tell if the downpipe is going to fit by looking at a picture of it dude. If they make it, charge that much for it, and have been in business this long with multiple local success stories then it most likely fits. I would personally go with full race however, they are an unbelievably skilled shop with world class fabricators. I went with AMS's manifold, however its probably never goin to get made again lol. We needed a 5 person deposit to get them to even make it again.

You have to use a 8mm(or 10? cant remember) vac line for your wastegate. Its probably just for external wastegates actually.

Well, i have reason for that. It doesnt matter how long or how well the company makes parts, nor how expensive it is. Ive seen HKS and greddy turbo kits that cost an arm and a leg and dont fit, happend to my friend with his MKIV supra, the manifold was so badly make the turbo hit the fender well and the IC piping didnt line up, and on other cars. Im just making sure. But it would still be nice to see a break in the xcessive dp to make it easier to pull in and out, or ill just have to put it in myself. It looks like a long snake lol

Yeah i would love the AMS manifold that thing looks so hot. I was so dissapointed when i heard they discontinued it.

[WDRacing]

And having the boost line for your wastegate is a bad idea. Having your line that long will cause a chance for creep and spiking. You want it as short as possible thats why people so often tap into the turbo so its only about 4 inches or less. But either way im pretty fed up with this bs. Telling people im fully built and having a weeny of a turbo on it and getting beat from pos stage 2 srt's. My engine and fuel setup could handle 500whp with not to much problem.

Dude, if the turbo will boost more then your 11 psi max problem with the vac line removed, then obviously its where the vac source is coming from or the wastegate itself.

I've had 2 Skylines and then my 240...all boosted, all vac signals come from the manifold. So saying it's a bad idea is simply incorrect, I had no lag nor boost spike or any type of fluctuations.

If the wastegate signal is from the manifold you don't see the pressure drop from the FMIC either, since the turbo will make up for it by adding a few lbs of boost. I've been doing this for awhile now man...before you say something is wrong, you may just want to try it out. There will be no harm done by running a $6 piece of vacuum line from the intake mani to the wastegate to see if it helps you run more boost.

For the record, you're on the right path by ditching that T25 and upgrading to a T3 flanged turbo. I'd buy the JGS kit, turbo, mani and DP combo is a great deal and has been more then proven to work very well.

WD