Blue = stock 06 revup
Red = mrev2 no spacer

Makes a lot of torque in midrange and dies up top, just like I said a few posts up.

 

Is it typical that theblue plot would be stock or base and the red would be the modded in terms of all the comparisons?

I do realise that red and blue might be used to seperate seperate runs on the same unmodded car as well.

Thanks for the reply.

 

I don't know about typical colors used. I imagine they can change the colors if they want.

Someone has to explain the dyno or else you won't know what's going on.

Normally people would only show dynos where the lower numbers are some sort of baseline and the higher numbers are the "modded" numbers. But in some cases, the winner is not clear.

 

What's so hard reading this dyno curve? In short, the mod did very good until 6k rpm, than something caused the ECU to pull timing (only explaination for such an abrupt power stall). It could be due to turbulences in airflow or it went very lean and started to ping.

The gains it did before 6k look unbelievably good though. If the flow was increased to an extend that it went lean and leaner through the rpm band and the extra power was made by bringing the A/F ratio to a healthier level there will be no other cure then a ECU reflash to enrich fueling after 6k rpm because after this point A/F might have become so lean that it would cause pinging.

 

well plenty for someone that has not used the device or is familiar with the output. I might be the only nugget here that doesn't know but I feel compelled to find out so I can interpret what is taking place.

 

thanks for taking the time to get me out of the weeds on this.

 

I didn't meant to sound arrogant, I am sorry.

 

no no no... I am just putting myself on blast here. I dont know and felt compelled to get this out. Dont sweat it.

My reply more of a self-deprecating humor kind of thing.

 

When you look at the torque curve's amplitudes you will notice that the "vales" are nearly perfectly inversed... THAT is very interesting! Tony...?

 

Its definitly a function of the runner tuning frequency.

The REVUP plenum (with shorter runner) has its own unique quarter wave length tuning frequency.

The 287 plenum (with longer runner) has its own natural quarter wave frequency. Because the 287 plenum has longer runners, the 1/4 wave tuning frequency is lower.

The frequency of either plenum is permanently fixed to its length and the speed of sound. Speed of sound is constant assuming the air inlet temperature is the same for each. As such, the runner geometry is fixed and so is its tuning frequency.

The engine on the other hand has a variable frequency because it has a variable RPM. RPM=Hz=Frequency

Since the runners sing (or resonate) at one frequency like air being blown across the top of a Coke bottle. The engine will either be in phase or out of phase depending on its RPM(Hz) relative to the runners.

What you see in the TQ curve is the differences of the phase relationship. In phase or out of phase. There is also the phase relationships of the harmonics of the runners. These can also be either in phase or out of phase.

The best analogy of how the different plenums work in relation to the engine is to think of how vented speaker boxes work. (that is if you are familiar with how they work)

The plenum is the box.
The runners are the bass ports or vent.
The engine is the variable frequency transducer or speaker.

You can tune the runners, plenum volume and engine just like a vented speaker box. Its really no different.

You can tune a speaker box for the flattest frequency response (TQ curve)
Or you can tune it to be peaky at one frequency and provide the highest peak.
Conversely, you can also tune for the greatest overall output regardless of peaks or flatness.

In the case of the REVUP plenum, it appears the runners were tuned to sing right at the very end of the RPM spectrum (7K RPM).

In the case of the 287 plenum, its center frequency sings at about 5500-6000 RPM.

I believe it is best to get the runner center frequency just below the RPM limit and not right at the RPM peak. This is because there is a boosting effect at the tuning frequency with diminishing boost to the left and right of the tuning frequency.

When you use a 287 plenum you get the boosting affect slightly below the tuning frequency(~4500), at the tuning frequency(~6000), and even slightly above the tuning frequency (~7000).

When you use a REVUP plenum you get boosting below the tuning frequency (~5500), at the tuning frequency (~7000), and even slightly above the tuning frequency (~8000)... only problem is, the engine doesn't rev to 8000 RPM. So the usable bandwidth is cut short.

This is why the peak numbers are good with the REVUP plenum but area under the curve is greater with the 287 plenum.

Thats basically how it works...

 

Thanks Tony. That even understandable to a nugget like me.

 

Wow i didnt know plenums had much more to them than just directing air.

 

+1

 

Yeah, this was a very good explaination. You get that Tony knows what he's talking about!

Tony, what do you believe to be the reason the power curve breakes down after 6k rpm and what would be the fix? Further improvement of the plenum design possible to cure it or will a ECU retune become a necessaty?

 

Tony, actually that DOESN'T explain why the area under the curve is greater with the 287 plenum. The upper boosting frequency appears to be above the engine rpm range for BOTH plenums. The peak is not useable at 7k no more than it is at 8k. You can see the curve just start to move upward at 7k but not enough to add anything to the area. So what is the reason for the MREV (287 plenum) making more power below 7k? I do not disagree that it does, although I will stick with the revup plenum for now, I just believe a different mechanism (or a different explanation) is at work here. Maybe if we knew the true reason, we could even extend the power of the MREV mod up to 7k.

 

When RPM is below the tuning frequency, fluid momentum predominates as the booster, but its predominantly about resonance and acoustic tuning. This where the most powerfull boosting will occur.

If you think there is a different mechanism at work, then please explain.

 

[quote=Silo

Tony, what do you believe to be the reason the power curve breakes down after 6k rpm and what would be the fix? Further improvement of the plenum design possible to cure it or will a ECU retune become a necessaty?[/quote]
More testing is needed on the REVUP before other ideas or solutions can be worked on.

 

I don't have to explain, nor do I know as I stated. What I said was, your explanation does not match the results on the dyno, and you seem to agree since you're asking me to offer an explanation.

 

So, to the thread's topic, Revup with V2/spacer looks good to me. I just got back from dyno'ing it, it'll take me a few to post up charts. Summary is this though:
I ended up with 10 - 20 ft/lbs gained accross the curve and 5 - 15 hp through it too. There is a dip between roughly 6.7k and 7k, but no more than 6-7 hp. I does actually pick up again right around 6.9k, it would be interesting to see this with a higher rev limit, for now I'll shift a few hundred under redline and call it good. Peak hp right around 6.5k rpm's, peak torque around 5k rpm.

 

Can't wait for results