Considering what the graph looks like IE min amount fluctuations but very tight like a vibration, yes I wouldn't rule it out. You wouldn't pick this frequency up on a common dial boost gauge is my guess. Have you ruled out spark blow out from too large a gap? This is a sensitive and common problem.

 

That is exactly what I have; a mechanical boost gauge in the car. That is where I first noticed it. When it fluctuates like the log in my OP, the needle jumps so much and so fast that it looks like a blur. The most recent log I posted it is much less noticeable...almost nonexistent.

I had previously gapped them when I was close to 400whp. I believe I set them at .025".

I also returned the car the car to as stock as possible and did a log. Everything looked good. Who knows....I'm finishing up tonight at the shop (removing the offset keyways) and going to bed. Off to the tuner tomorrow!

 

You probably need to gap your plugs down to .018" if you're shooting for 500 on E85. I had misfires even at .025". They were gapped down and the misfires cleared up and made about 40whp more.

 

do the iridium plugs have spark blowout as easy as the copper? i am at stock gap 2 steps colder running 16 psi @8500 rpm

 

I gapped them to .019" the other night before I went to the tune date. There are a few factors that played into my tune that I will get into below.

I don't know for sure, but I do know that copper's conductivity is far superior to iridium's. Based off that alone I would say copper is better as resisting blow out. The trade off is that they would not last as long, especially in a forced induction environment. I have read that the cores of all plugs are copper though and the tips are straps are the only thing coated in either platinum or iridium for the longer service interval. If this is true, the resistance difference would be minimal.




So I got tuned yesterday. I put the SOS crank back on and went with a 3.4" pulley on the blower. I did this so that I would hopefully not exceed 15lbs. I could have achieved essentially the same ratio with my 6.6" crank if I had a 4.0" blower pulley, but I didn't have one on hand. I never got a chance to log this combination before I went to the dyno though. I can only assume that the fluctuations would have been kept down due to the lesser amount of boost. I can still test the theory to see whether or not it was the tune by loading my old tune and test driving it to see if the fluctuations occur.

Anyhow, we did not see any abnormal boost fluctuations while on the dyno with that setup. Whether that be from the larger pulley combo or from the tune is still unknown. It touched 16psi at around 8250rpms. There is still something funky, and I think it may be in my tune though. When the tuner first started, the belt was slipping (all I had was a cheap autozone belt since no one locally carried anything worth having) and I was only getting 12psi at 8200rpms. The funny thing is it was only making 330hp. On my previous tune with the 1220 blower I was making 11lbs and seeing 375-386hp. So that is a smaller blower with less psi making more power? Something didn't add up. The tuner and I talked about it and he said that his dyno always read a little lower (both were dynojets) on average.

Moving forward...I tightened the belt and we started seeing the 16lbs up top. The MOST the car made was 406hp at 8200rpm. And that was with the filter off and fully tuned. With it on it made 395hp. I know a dyno is just a tool and not a number producer, but I was a disheartened. I kept referring back to the dyno reads low and it was actually stronger than before. So I go for a test drive once it is all done. The car feels almost identical to the previous tune on the 1220 blower. So that tells me that the dynos were pretty close to reading around the same amount. I find it hard to believe that a blower that should make the same power with 3lbs less of boost is making 20hp more with 4lbs more of boost. From my calculations and from other's experience I should be around the 435hp mark.

The tuner is known for having a very conservative tune and he is a Nissan guy at heart, not a Honda guy, and especially not a S2000 guy. Do you think the tune could be holding it back 40hp? I'm happy with a conservative tune, but I feel like this may be too conservative. I spent a LOT of money and a LOT of time to have the car feeling the same as it did before.

Oh, and we never got around to the E85 tune. He made the map up and I am going to do some logs on E85 and he will tune it based off those. He said he expected 15-20hp more from the E85...again sounds off. I figured at the 400hp mark, around 50hp more was to be expected on E85. I also need to make up another map with my 2.8" combo to if I plan to reach the 500hp mark. I was already in the process of learning to tune, but this really has opened my eyes to being able to do it. It is just a matter of me learning the AEM software. The tuner was a great guy and was very knowledgeable, but maybe a tad conservative. Then again, it could be my car. It just doesn't add up though. The engine is healthy (225 compression across the board on a cheap gauge, and 15% leakdown across the board) and I feel like it could do more safely.

 

What do you mean by "conservative"?

To get the absolute best out of the set-up, you normally tune to the point of det and then pull 3-4 degrees of timing out of it to make it safe (along with ensuring the AFRs are not too rich or too lean).

Don't get hung up on the numbers as you can't compare dynos. If you want to feel better about the current tune, is there any reason why you cant take it back to the original dyno to get a genuinely comparable figure?

 

15% leak down is pretty high for a stock engine, its outside of spec, so id say that's not helping.

 

I could and plan too as there is a dyno day soon, but it feels almost the same as before with my butt dyno I mean conservative as far as timing goes. I never saw him reach the destination threshold. He tuned it at what he felt was a comfortable amount of advance and left it there. What do our stock knock sensors read with "normal" knock and detonation knock? I know our sensors aren't the best in the world.


Anything less than 20% is considered healthy for my gauge. I've tested several low mileage engines and my gauge reads between 15% and 20% usually. On any other gauge the numbers would be lower, but i've found mine reads high on average.

 

You might need to break-in your belt some more (like a couple hundred miles) and make tensioning adjustments. Otherwise, you might now see the full potential of your setup. You should acquire another leak down test kit. Mine is about 1% leak down across the board.

 

I also have some surge, vtec at 5400, we are lowering it to 4000 to see if it goes away.