Underpowered?

[HP Junky]

I finally got a friends r33 gtst on the dyno today and he was telling me it lacks power in the top end. Rb25det fair. Hks pod. Z32 AFM apexi power FC. Upgraded turbo not sure on size smaller than a gt3582r. For facing plenum 80mm tb e85 1000cc injury 15psi boost 3" Full system including dump pipe. Was tuned by a shop and gave a dyno sheet that showed 313rwkw. No today on the dyno it pulled 205rwkw. Haven't investigated yet but any ideas what might have happened timing not advancing or some stupid little think before I go full surgical on the car. 

[GTSBoy]

No boost. (look at the chart).

Edited June 7, 2020 by GTSBoy

[Duncan]

yeahbut. and rb25 with no boost will make about 100rwkw not 205. 

[BK]

Blocked cat, check it first.

[HP Junky]

OIt makes 15psi of boost on the graph that's the lower 2 lines. I'll check the cat it looks like it has a small one but could be missing as it's a dedicated track car.  Here's some pics. I'll check the cat when I lift it up to run new fuel line. Will let you know. Thanks.

[GTSBoy]

1 hour ago, HP Junky said:

OIt makes 15psi of boost on the graph that's the lower 2 lines.

No, the boost axis on the right clearly shows it making about 2 psi before the line disappears behind the legend. If it makes it as high as 5 psi on that chart I'd be very surprised.

[GTofuS-T]

6 minutes ago, GTSBoy said:

No, the boost axis on the right clearly shows it making about 2 psi before the line disappears behind the legend. If it makes it as high as 5 psi on that chart I'd be very surprised.

confusing af... there's 5 lines on that graph, I gather the 2 that peak lower than the other 2 i.e. around 15psi on the boost axis are the boost lines? there's no torque for some even more confusing reason

[kowalatea]

Not sure about 100kw drop but difference in altitude/temp in tuners shops as well as calibration of machines could play into it. Might add that they could of tamed the tune after getting rumbers for reliability in their work. Some food for thought 

[KiwiRS4T]

I see only one boost line which barely gets off the ground. What is the boost gauge in the car saying? the original 300+kw sounds right for the turbo. Have you checked for boost leaks?

[BK]

I think you'll find that little green trace on the bottom is one of the boost traces that is still being recorded after the full throttle backoff at the end of the run. Both green lines drop straight down and it starts reverse tracing.

Drop the exhaust at front pipe and run it again. My 33R went from 330kw to about 200 with a blocked 4inch 200cpi magic cat. Front pipe only run shot straight back up over 340.

[HP Junky]

The green line at the bottom was from not ending power run before throttle was let off that's why it's there. Boost in the car is 15psi. I'm going to drop the exhaust tomorrow and have a look. Then move on with checking cooler piping, plenum manifold gasket and everything in the whole setup to see what the people before did or didn't do and just make sure everything is working correctly. Thanks for all the replies. 

[BK]

That's what I thought. Check it out and let us know the result dude.

[tridentt150v]

Could it also be a wastegate issue? Stuck wide open?

[HP Junky]

Pulled center section of the turbo to tail pipe 3" exhaust off no cat no restrictions in rear muffler. Pulled inlet plenum off to check gasket as it was very hard to tell if it was or wasn't sealing might have had a very small leak but don't think it's the problem. Going to pull turbo and manifold off next. Checked cooler and piping for leaks by pressure testing. Once exhaust side is off I will be doing a leak down test as it will be easier to hear leaks through each port. Will post out come of all tests and inspection. 

[BK]

Did you actually run it up on the dyno with just the front pipe to verify ? Just because you looked inside and can see through it doesn't really mean anything, a blocked cat is not always visually obvious, or is there actually no cat converter ?

[HP Junky]

There is no cat at all in the system. Haven't had it back on the dyno yet. Pulled turbo and manifold off very very small exhaust leak on rear 2 cylinders but not enough to cause a problem. Turbo looks good. Removed plenum to replace gasket no leaks found but replacing gasket to be sure. When I get a chance I'll get it back on the dyno. 

[HP Junky]

Well after pulling plenum, turbo and exhaust manifold I finally found the problem. See if you notice it. 

[admS15]

That looks like it's eaten something. Must've been hungry.

[PranK]

2 hours ago, admS15 said:

That looks like it's eaten something. Must've been hungry.

Or something ate it!

[GTSBoy]

Well, there was definitely something wrong with it!