mark kibort

Im afraid the news is not good. I tried everything to be exactly the same. same , gas, warm up ritual, rpm start, etc. during the dyno session with the spacers. The results? HP not improved, actually a slight loss, but major loses in mid range torque from 3000rpm all the way to 5500rpm.
It also seemed to richen the mixture up so i turned the regulators down a bit, which helped a little, but not much. The runs were the runs and I did 5 of them. Below is the best of the runs compared to the last runs without spacers a few months ago.

I suspect maybe the turbulent flow at any rpm with the covers spaced off, was huring the air flow, and yet fuel still was flowing, but that is hard to imagine unless the MAF was going open loop and was pumping fuel in response to rpm not hot wire signal.
It does explain my 60-80mph runs being slightly slower 2.1 ish to 2.4 second-ish but my 80 to 100mph being near the same.

From 5700rpm to near redline, there is no real difference, i suspect for the same reasons that when flappy vs no flappy is tested, this area is unchanged and seemingly uneffected by the covers being close to the bell mouthed inlets.

Here you go.

928SS

worked on mine... was this a stroker?

mark kibort

yep, 6.4 liter. I know Brian had about 7-10hp gain on his stock S4 as well.

mk

928SS

hmmm... vacume leak or wot not working? maybe ck the usual suspects as in any tuning situation?

maybe the eram or intake has an impact?

90 S-4

SHARKTUNING...

mark kibort

nah, idle is fine, small vacuum leaks dont really effect mid and high rpm hp.

I also tweeked the fuel while there to lean it up. If it was going to help, it would have shown some gains in the leaner areas. BUT, there was no change. The curve was the curve. again, I did road tests before hand and after and there was a slightly slower 60-80mph feel and time to it. Brian said he did lose a little in the mid, but made it up later in the rpm. fuel is not going to get back 30ft-lbs of torque, even if it is at under 11:1.

All I can do is pull them off and see if it changes, and /or go back to the dyno to verify.

This is one of the reasons I wanted to go with the 85-86 injectors . I think the higher pressure would have more flexibility and certainly would have supported this HP range. Ill put a meter on this and see where im at. the other thing is, who knows how accurate the wide band is at the shop.

Plugs dont show this kind of richness either. they are white tiped and look fairly decent.

Just maybe, the porsches engineers got it right, for what it is. the restriction could be in the runners and main air feed ovals, not so much in the plennum size.
If you look at the curves, the flappy open RPM range, seems to be effected like the flappy was still closed. maybe with the spacers the resonance tuning of the open flappy cant take its effect. Lots of possiblities. also, with the same air/fuel last time in the beginning, im down 30+hp and torque. that is the mystery

mk

Did a run with eRAM as well, most all runs were without it. no real difference.

928SS

iirc, devek spent a LOT of time screwing around w/the intake and they had some pretty sharp folks around from time to time. but never could get much out of it.

NOTE:
DEVEK did do lots of early intake work...with little positive results on stock engines, and modest results on strokers...built 520 rwhp plus using stock intakes and ecu's.
The factory did a darn good job for stock engines
DEVEK also built and tested spacers over 10 years ago....the results are speaking for themselves
DEVEK never did any collaboration with Threshie
DEVEK and Louis did the a throttle body collaboration on a stroker and made 550 plus rwhp.
END NOTE

always a trade off between low end and big end power w/out a dual plenum setup. w/smaller sized stuff it's real critical.
iirc, subaru had a 3 plenum setup, bmw had an adjustable/computer controlled intake runner that was pretty slick on the 3 series.

w/the 6.4L stuff and larger, there's so much bottom end anyway that tuning for the big end isn't such a big deal in terms of sacrificing grunt for glory for a track motor, imho.

keeping it streetable is another story... guess we'll see what downtown brown ends up with. could be interesting, but every time I look at the length of the path intake air has to go on that these things, the less I think there is much to be had.

I do wonder what would happen if we just sealed off the bottom, pulled the side plenum covers and had dual MAF's and TB's going into the sides direct to the front air dam on each side... seems like I'd be pretty close to an ITB at that point, without all the plumbing headaches.

IcemanG17

MK
Not what I expected.....at all...... I just reviewed my dyno sheets and the before-after on widow (5.0L with race exhaust but stock S4 internals) has a non op flappy on the "before" so it looks kinda funny...the better example is the runs I did on sharky that gained 7hp up top with most of the gains above 5600rpm....heres the pic

928SS

how do you "revise" a dyno run? w/photoshop?

IcemanG17

Rob
I like to use crayons.......since it makes a much more colorful line thats easier to see.....

928SS

sounds easier than a re-run

fwiw, my last dynojet run showed 40 rwhp less than before a sharktune with the blackbird, bigger headers and larger injectors which showed 40 MORE on the mustang dyno at gregs...

car clearly runs way better though... maybe there is a dyno issue? wouldn't take much for only a few rwhp... sure all the correction stuff is right? (maybe U need brian's magic crayons?)

ROG100

Dissapointing - I also heard they do not work on SC cars either.
Maybe after we run a dyno on a stock car we may see something more positive.

BC

Marks dyno is totally inconclusive since he has no tuning changes of any sort, and is screwing around randomly with his fuel pressures. Non-repeatable and anomalous.

BC

You can't simply change something on an engine and not change its tuning parameters and expect some giant leap. Even X-overs, when not properly tuned, do not create large leaps.

ptuomov

First, sincere thanks for Mark and Roger for reporting the negative results and not sugarcoating them. If people sometimes find and publish results in which their products or dyno tests show no improvement, that adds hugely to their credibility when they report an improvement from some other product or in some other project.

Second, doesn't this mean that nobody has ever been able to improve the stock manifold in any way?

Here's what I've got so far:

Extrude hone -- no gain.
Replacement airbox -- no gain.
Aftermarket air filter -- no gain.
Overbored throttlebody -- no gain.
Plenum spacers -- no gain.

It seems to me that with the basic design choices that Porsche made, it's hard to do better. To do meaningfully better at any rpm range, one would have to go to a totally different manifold design, such as short runner single plenum.