Do you think it could be the Utec ?

 

Unless it's datalogging is WAY off no. My timing and fuel are perfect. I thought about that for a bit, but everything works correctly and the car has a very smooth powerband.

 

The reason I asked was my shop tuned a TN kit on the Utec and he said he could never get the power out of it that he thought it could easily make . I never seen a dyno graph or any of his datalogs , but he said it looked all good just didnt make the power that it should .

 

Brian, the car is clearly not breathing up top. I'd take Alberto up on his deal and have Shaun or Jeremy fix his manifold.

 

this sounds very familiar.....(no pun)


and as BRiM said...def not the turbo kit or the exhuast....and not the EMS probably either... and even with stock heads and the stock plenum...still should be able to pull way more than 500.... engine ->

hope you sort things out!

 

Im gonna vote for poor compression,valve float,or improperly timed motor...

 

I hate to say it brian, but I also think the motor is the issue. Cams, plenum and what-not will help up top, but don't think it will completely correct the problem you are having. Did you do a leakdown on the motor along with the compression test?

The stock top end should flow plenty enough for your goals.

I hope you get this sorted out... good luck

 

As stated in my first post...compression is perfect. And with the 10psi tune on my unichip the car pulled just as hard up top as it did with the stock motor.

What is a leakdown test going to tell me about why my car won't make power above 5500rpms that a compression test won't?



I don't want you guys to turn this thread into a BZM bashing thread...the motor is FINE. The car made basically the same power with the built motor on 10psi that it made on my stock motor on 10psi.

 

Can anyone show me a dyno of a setup like mine with STOCK cams and STOCK upper and lower plenum @ 14+ pounds of boost? I can't find any setup like that.

 

I'm surprised no one has mentioned that your AFR graph shows almost flat 10's on the top end.

edit - nm I just noticed it at the bottom of the post. Is there any reason for running so rich?

 

Hmm, the only difference is I do have the APS plenum, but that shouldn't be near the 30whp difference between you and me. Can you say where you had the dynojet dyno/tuning done?

If you didn't see it on my earlier thread, here's my dyno @ 14psi at GRD.

 

I am not bashing on anyone, just that I have read about something similar to this before... it just sounds all too much the same.

That said, I think leakdown is more telling than a compression check. Tells you more about the condition of the cylinders and rings and the heads and valves. I think now days, a compression check alone doesn't mean all that much

I have my chart from my tune at 14 psi peak tapering to 11 psi at redline on my previous motor (8.8:1 compression, APS 2.5" downpipes and exhaust, stock heads and cams, but a crawford plenum)



Actually, I found this chart... I think it is mine from last yr based on the dates. this would be comparable to what you would be looking at for power. This is labeled 14 psi -

 

it is more than just the peak power, BriGuy's power is just falling off the table

 

Gotcha.

 

Brian, this might be a stupid question, but are you sure your vvt is working properly?

 

That's because of the scale of the graph. It ends up about mid 10s, but runs about high 10s on the street. We started with mid to low 11s and only saw about a 5whp loss from fattening it up a bit.

 

Actually our power curves look very similar until 5500rpm which supports my theory that the plenum really would help with the stock cams.

 

I just did a little reading on compression vs. leakdown and the only thing a leakdown test tells you is compression over time. The higher the rpm the less leakdown numbers matter. For example a car with bad leakdown but good compression would have a bad idle and low rpm response, but high rpms would be fine.

I've ruled out the motor as the issue. It it was making very poor power all the way through the powerband then I would buy the motor being bad theory, but the fact is it make good low end and midrange power.

 

If it wasn't it would affect midrange power, not top end power.

 

Is there a switchover for higher RPM's in Nissan's system?