measured mine at 6000rpms .. 535 cfm .. using datalogger ..
looks like we're overflowing the stock turbos at this point

Anyone log the flow of the bigger turbo setups ??

 

My handy dandy 2.0L boost chart shows 534cfm at 20.6lbs boost at 6000rpm, which as you indicated, falls just outside the topographic 'sweet spot' in the compressor chart.

 

Based on your figures:

122 cid * 6000 * VE * 2.4 PR / ( 2 * 1728 ) = 535 cfm.

Thus VE is 105%... a little optimistic? Or is it a full race engine?

 

I have heard of people on race gas (116) peaking at maybe 25 and dropping to 20 at redline or something similiar. Is the high boos early in the rpm's still at a good spot on the compressor map?

 

Why don't you re read the post again and tell me which part of data logger you don't understand ???

True bleu logging dude !!!
You'd be surprised what you find out when you log it

 

my logger is around 31-33 lb/min

 

Basically to achieve that volume of airflow, your engine needs to have a VE of 105%, which is more commonly found on race engines. It's very unlikely a 4G63 comes from the factory with VE that high.

So how does your datalogger measure this amount of airflow? Using MAF? If so I would suggest that the reading is at least 5% off the mark, perhaps as much as 25%, more so if you've done any sort of intake mods.

 

With a decently designed 4V engine, one can expect to see VE of >100% at the torque peak, assuming the intake and exhaust system are tuned accordingly. Past the torque peak, the engine is becoming mechanically less efficient, and the actual VE should drop gradually as the rpm is increased.

FWIW, I assumed 100% VE in my above calculation.

 

31lb/min at 21psi at 6000RPMs seems a bit low to me.

 

that is at WOT at like 7200rpm

 

Hmm.. I wonder which should I trust .. my datalogger or your calculations ??
think I'll stick with real life ..
OR maybe you know the exact VE of the engine ??
OR maybe you live in a world of mathematical formulae only ???
Get outside the world and take a break once a while ..

Logged about 26-8lb/min at 7500rpms ..
My previous car logged flow in excess of 120% VE (its a VTEC)


At 7500rpms my boost has tapered to around 14psi .. my wastegate flapper is leaking

 

Or maybe you just have a boost leak. Pressure test your intercooler pipes.

On my car, with HKS cams, I get around 41 - 42lb/min at 23psi or so with an Evo III 16G. Each lb/min is roughly equivalent to 10hp on a well tuned car.

 

You don't have to trust my calculations. You can do them yourself.

The theoretical airflow of a stock 2 liter 4G63 engine at 6000 RPM at 21 psi is 508 cfm. This is assuming 100% VE. But according to your datalogger it's showing 535 cfm which is 105% VE.

All I'm saying is that when the experimental data varies from the calculations, it pays to find out why. It's the basis of the scientific method.

You should have kept your previous car. As a frame of reference a modern day F1 car has around 120% VE peak.

 

DUDE you STILL DON'T GET IT ..

Stop your calculations and get out into the world once in a while .. there's life out there you know ..

I calculated against a VE of 90% for my evo and it still outflowed the turbo .. now I have datalogged an ACTUAL massflow that shows the engine being MORE efficient than I thought.. Real life versus a bunch of numbers ..

Hmm. your point being ?? STILL a NUMBERS guy ..
oh well.. when you don't get .. you don't get it ..

 

Using a datalogger to determine "ACTUAL" (your words, not mine) massflow is like sticking a thermometer into the ground to determine the time of day. The only way to do it accurately is to use a flowbench.