MAF vs Speed Density w/no MAF
 

I had a repeat customer come in today with a new turbo kit and some other tweaks for a retune. He also wanted to move to stock ECU Speed Density.

I ended up tuning the car first with the MAF and then swapped everything over to Speed Density to do a comparison. As I don't think I have seen a comparison yet, at least on the stock ECU, with a normal car, etc.

Some details on this car (notice some details that make this more of a "normal" every day Evo)

2006 Evo 9

Mods:

Stock Cams
Stock ECU
Stock Headstuds
Stock head/block/internals
3" TBE no cat
Upper/Lower Nisei IC Pipes
FMIC (not sure what kind)
Tial bov (VTA)
BlaqOps progressive Double Pumper fuel system
FIC 1200cc injectors
GM 3 port boost solenoid
OmniPower 4bar map sensor
35R .63 hotside
Tubular Exhaust Manifold
Custom intake tube with K&N cone filter
GST Motorsports tune
E85

Now the overlay. ;)

Stock ECU with MAF (dotted lines) vs. Stock ECU without MAF on Speed Density.

Notice it's pretty much the same power. This was at 27.5 psi across and exact same AFR flat on BOTH tunes. Same ignition timing as well.

So this tells me, at this power and boost level, with this turbo, on this evo, going to SD will not free up any power.

http://norcalmotorsports.org/users/b..._SD_111509.jpg

Boost overlay:

http://norcalmotorsports.org/users/b...esse_boost.jpg


- Bryan

this must be jesse's car not bad at all for stock head studs

That's interesting. I don't understand how removing a restriction from the system isn't helping on power. The only thing is there must be a larger restriction (stock cams maybe) elsewhere that is holding it back from seeing any more power.

I would say there is something else going on. No way the maf doesnt hurt flow of 35r at that power level. Was same intake and filter used before and after? If same filter was used the filter itself may be more restrictive than maf so no difference would be seen removing it. Or if filter was changed the new filter may have been more restrictive than old one. dont know, but could be a whole host of other things as well.

When you converted to speed density, did you keep a 3" intake pipe with the filter?

I am assuming that you had a 3" inlet pipe since you were using a maf. Did you keep such inlet pipe on the car? If yes probably that's why you didn't see gains. I think this is the problem since although you removed the maf you might still be using a 3" inlet pipe rather than a 4"...

This is of course an assumption that you are still using a 3" inlet....

interesting test...I'm still on the stock ecu/mas at 705awhp/539tq (dynojet). I recently bumped the boost up from 38psi to 45psi and it only went up to 717awhp but the tq jumped up to 603tq. This leads me to believe that I'm finally finding a choke point. However, that doesn't mean it's necessarily the stock mas. Next up is suspension work and after that I'm going to look into a better intake manifold. I'm still rocking the stock one PPI ported for me a long time ago.

No a larger K&N was used. I believe it was 4" by 6" but I might be wrong about the length.

MAF was using a 4" induction off the turbo to a reducer to the MAF to a MAF sized filter. No MAF was 4" all the way to 4" filter.

I understand the need to question the results, and I am all for questioning. I just really think the MAF is not a restriction at this boost and power level. We might start seeing the advantage of MAF less with more boost on this turbo, but it won't happen currently on this Evo with stock headstuds and stock cams.

All is not lost however, the car drives great with the VTA Tial BOV and the idle is rock solid with no "clutch-in" dips, etc. I don't think I have ever seen a Evo lock on to target idle RPM so well before.

- Bryan

How does the car drive out of WOT?

GOOD TEST MAN , I was thinking on going to sd

Very fair test then. Interesting notes on the idle, this is a MAJOR problem I've been struggling with on my car for a while now, clutch in, dropping to 500rpms and maybe dying, maybe coming back to 1000 and living.

When I switched to SD I didn't really feel any big power gains least from the butt dyno - it was more the drive-ability was so much better, all around the car felt smoother...

thanks for the info gst - its always nice to get good honest results and no bs from your posts and tests. :beer:

The test makes sense at the lower levels. Chris you can definitely benefit from SD at your levels however.

What Rom ID are you currently trying to use? I too have an 05 and when we changed my rom id to run tephra v5.10 everything worked however my idle wouldnt always catch. Did your issues arise when switching over to speed density? Seems more common coming from a 2005 in general. I am currently running on my original rom id with v5...

My driveability improved incredibly, I have Tial Q and Kelfod 272's idles rock solid and AFRs are perfect. I think one benefit was quicker spool but its hard to tell especially since im on stock turbo e85 and I struggle to stay out of boost just cruising.

I'm not on SD, but I'm running Tephra v7t5 or t6 96530706.