Lizard928

Jeremy,

That dip is the flappy valve opening.

U-928

Ah, that's right...32V. I'm stuck in a 16V mindset. That dip is mildly annoying looking. How much of that loss does one "feel" in driving it? Haven't driven a 32V.

PorKen

Those are the new plastic body injectors.

I'm using the metal body type. There should not be a big difference in output.

It only looks bad on paper. Past 3000, it all happens in a blur.

The first torque peak is from intake harmonics. (There's also a third peak at 5200.) 16Vs only have the second peak.

S3s have a much longer and deeper dip (ahem), but you don't really feel it, because the first peak is so strong. (Red line, below.)

S4-up have LH controlled variable intake volume, so the valley between the first two peaks is minimized. (Blue line.)


As you can see, I have some work to do to catch up to my S3 manual chipset.

Tom. M

Whats that sound I hear?????? why it's the cries of the 32V 85/86 owners lamenting the loss of their tuning god LOL .......

Glad to hear you are making progress on the S4 chipsets....... Are you overlaying SAE and non SAE numbers in the graph above?

PorKen

I wonder if S4s need a little cam retard to even out the TQ/HP? Or, is it just not breathing well enough, yet, with the stock exhaust?

Or, if it's an effect of the Racing belt, which effectively does not stretch, so doesn't get belt stretch induced high rpm retard?


Wishful thinking

That's my old black, fully tweaked '86.5 manual overlayed with this new silver stock early '88 manual, both SAE.


This dyno run was to get a stock baseline.
I flashed the EZ with what I've been running lately just to get an idea if my 'bracketing' rpm theory works on the S4.

Don Carter

I can feel my wallet getting thinner already....

Ken, perfect timing! I just picked up an 87 5 speed.

PorKen

FWIW, I must admit the S4 does put down some good numbers, right out of the box.

Compare the graph below, which shows my old '86.5 manual, AutoThority vs. S300s chipsets, both WITH X-pipe.
Stock S3 w/cats is in the 250-260 range.

PorKen

Congrats!

Expect to be well fleeced...it's common knowledge that S4 (and GT) owners will pay huge sums for a couple of extra HP.

PorKen

Flappy open vs. closed.

Hilton

Now I see the text in the top right.. so hard to look away from the lines.

I was wondering if it was due to Reiki or healing crystals in the gas tank, or some kind of Porken-voodoo

IcemanG17

flappy-shammppy....don't miss that at all.....like my old school 4.5L brute HP....simple for a simpleton like me!!!

gruffalo

87 S4 5-speed: check!
X-pipe: check!

I'm gonna buy your chipset instantly when you're done

Jon B.

I'm curious to see how much "better" an S4 really is at making power with these sorts of tweaks. If it responds like the S3 then that solidifies my choice for "next" 928. I have a feeling the intake is going to be a big factor though. S3s don't have the flappy to worry about. Cams are more aggressive too.

Lizard928

Honestly, I think that the S4 will not see as good of numbers without different camshafts.

Hilton

This will be the kicker.

S4's with better cams are the 928GT - i.e. combining S3 cams with S4 heads/intake.

I'm hoping Ken has a spare set of S3 cams under his bed and, in frustration upon reaching the max potential of an S4, will finalise the S4 chips, and get the one intake cam modified so S3 cams fit in an S4 (i.e. quick/cheap solution to making an S4 into a GT)