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So got another tune today and full boost is coming on late again. Full boost is at almost 5000 rpms. Tuner says full boost should be at like 3800 rpms. Power is also falling off early. I have BC turbo cams, crower valve springs and retainers, 68mm throttle body, port matched b18b intake manifold, ported b18a cylinder head, t3/t4 .48 AR on turbine side with a billet compressor wheel, spoolin log manifold, 2.5 in exhaust, 9:1 compression ratio, tial 44mm. Those cams should be good till 8000 rpms.
So after the tune last year, I had a clogged cat and symptoms where even worse. I have the Cat hollowed out now. The clogged cat killed the turbo after maybe 400 miles. So ended up with this current turbo which is brand new.
My tuner thinks it's the log manifold. He says there is too much back pressure in the manifold. Boost isn't stable either. Boost plot was kinda wavy on the graph. Don't have a photo of it. Here is a photo of the TQ and HP graph. Any idea what could be causing this? Engine only has maybe 3000 miles on it and cam gears are set to 0. Any help would be awesome. My tuner has me convinced I need a ram horn setup. Oh.... The graph is at 11psi. We were turning up the boost from there but weren't making much more power.
Meant title to be low power not lower. Last dyno run with the clogged cat I only made 190hp at same boost. So it is better. What bugs me is how laggy the turbo is and how power falls off so quick. I also have JG 303 cams, but the only time I ran them was with the clogged Cat. Not sure if they would help.
A tubular log isn't the best for max HP numbers but a tubular log excels in turbo spool. With a tubular log and a .48 AR you should be in full boost way sooner. Californiadad made over 500whp on your same manifold. You need to find your boost leak.
Found a couple of boost leaks. Fixed them and it didn't help the turbo lag. Gonna do a leak down next. Don't see that being a problem. I did a leak down test 100 miles after the full engine rebuild and it was fine. Now it has around 3000 miles.
How about degree the cams? Just because they are set to 0,0 doesn't mean that they really are. Looks like back pressure could be an issue as well, but you can't rule that just yet.. That's a decent size cam for that restrictive manifold.
Cam timing is all good. Fire ring is in the wastegate. Is there any one else running similar cams with a log manifold on a non vtec? I haven't tried to degree the cams yet. My buddy thinks the cams are too big for the manifold also. I could throw stock cams in it, but then it wasn't worth buying valve springs ,retainers, and port work. I would rather switch manifold then cams.
I'm thinking it's a cam timing issue as well... if everything else is fine with the setup and you've found all of the leaks then it has to be a mechanical issue somewhere.
either the cams aren't timed correctly or slipped out of time
wastegate isn't closing 100%/creeps open/leaks
boost controller issues: tuning/settings, allowing the wastegate to open prematurely, bad solenoid (ebc), or it has the wrong ball or spring in it (mbc), incorrect installation, etc.
Also what size downpipe and exhaust are you running? if the exhaust is on the small side then the excess backpressure can delay response times. if it has a flex section then it could have collapsed internally and running a cat also causes higher post turbine backpressure due to the restriction which can also delay response times.
all of these issues will also cause an obvious loss in power.
he's saying that since they aren't stock cams you can't just set them at 0,0 with the cam gears and line the marks up, you need to physically degree the cams and compare your findings to the cam card data to ensure that the cam timing events are happening at the proper time in relation to crank rotation BTDC and ATDC.
you can't just toss them in and expect it to be right.
Solenoid is new. I'm sure the boost settings in the tune are right. The tuner has a lot of experience. Whole exhaust including down pipe is 2.5in, magna flow muffler. The cat is hollowed out, so no worries there. I will have to look into setting the cams correctly. So I need to use a degree wheel right? I guess I could always throw the stock cams in to just see what it does.
+1 boost leak.
make sure blow off valve is not leaking make sure the wastegate spring is strong enough.
From there you might have to look into the cam timing make sure there is as little overlap as possible.
With your exhaust housing and 2.5" exhaust on a small turbo like you have mentioned you should be seeing full boost closer to 3000rpm or better.
If so you're at the limit of the turbo.. between the small turbine wheel and small turbine housing you won't make any more power regardless of what compressor wheel you have.
It's a t3/t4. I was told the compressor is 59mm and flows 53 lbs/min. P trim turbine. I just bought a .63 ar, v band turbine housing for it. I have a lovefab mini me manifold on the way with a 3in downpipe. Also have a 3in exhaust system to complete it. No cat. I figured the manifold should help. Did a leak down test and I could hear air leaking past my exhaust valves on cylinder 1 and 4. My leak down gauge isn't accurate, so I couldn't base results on gauge readings. I pulled the head and brought it to the machinist. He did a vacuum test and everything seemed fine. Kinda stumped on that one. He also told me that .020 has been milled off the head. So my compression ratio was prolly close to 10:1. Bought a .051 thick cometic to get it back down. I did notice an exhaust leak between the manifold and head. Also at the wastegate And manifold. Hopfully put the car back together and get better results. My goal is 350 hp. Would I be better running jg303's or Brian crower turbo cams? I have both. Thanks for everyone's help.
P trim turbine!!! Meant for a t4 housing and known to be laggy in a t3 housing. I have a super 60 compressor with p trim turbine. My dyno looks like a NA dyno. Very laggy for a small turbo. Reason I just ordered a 5454. This is on a 100% stock gsr longblock. Wasn't able to make more than 305 whp@12psi. Could not build more boost.
Exhaust side is: Inducer 74mm Exducer 64mm (almost as big as a gt35)
So that could be part of the reason I have such slow spool time huh? Great. So I could have the guy who built the turbo just change the turbine wheel.... Right? What would be a good wheel to go with?
I haven't run the new P trim v band housing yet. The guy I bought it from will let me trade it in on the one I want. Whenever lovefab sends the housing back I can swap it out. I just measured the turbine wheel and its definitely a P trim. I will go out in the garage and measure the compressor wheel right now.
The thing is AGP caters to the SRT4 crowd so that turbo was designed with a 2.4 liter motor in mind, hence the large turbine wheel. Where that turbo might be a responsive street turbo for a 2.4l motor it will be a turd on anything under 2 liters.
You size the turbo around the motor, not the other way around. Also don't buy a turbo just because it's cheap. Price has zero to do with if the turbo is properly sized for the application and power level. As you're finding out it's a lot of headache if you get it wrong.
I also don't see why anyone would take back a used turbo. Is he swapping turbine wheels or giving you a new turbo? Did you buy direct from AGP?
I'll have to look up the compressor wheel. The large gap between the exducer of the wheel and the backplate bugs me a bit, clearly this CHRA was machined to fit a larger wheel than you have.
You need to double check your measurements, I can't find **** about that wheel.
You need to take your measurements like below..
The inducer should be measured at the very tip of the blades.
The exducer needs to be measured at the very bottom of the wheel where the blades meet the base... No higher no lower or else the measurements can be off enough to make the effort of finding a compressor map impossible
Well I called him up today and he said the compressor wheel is same as a power stroke. So I think I am just gonna give up on this turbo and buy another one. So a garret stage 3 turbine side with a .63ar, and a 57 trim to4e compressor side. That sound like a good match for the car? I would like 350 hp. Thanks.
09-19-2014, 10:31 PM
Lower power. Turbo lag
