slate blue

Hacker I have looked into this also, there is one huge difference and I am not surprised that people miss it and I don't know why they do this, that is Dyno Dynamics has two different maps for lack of a better word.

If you put the Dyno Dynamics into "Shootout" the result will be way lower. The Ford 5.4 litre engines do 215 rwkw to 232 rwkw They are rated at over 300 kw at the engine. (290 kw in the video) The engine in our Holden's, the L94 headed Gen IV engines do about the same, the LS2/3 a touch more. A video that backs it up and that shop uses Dyno Dynamics.

http://www.youtube.com/watch?v=OTEiy...yer_embedded#!

On the same dyno my puts out about the same power around 290 to 311 rwhp or a low of 220 kw to 235 kw which is why I have always quoted the approximate flywheel hp on my car as in the 375 to 390 range. The DD machine is said to be by its manufacturer's within 1% of eachother when running in Shootout.

When not in shootout the numbers can be anything the operator wants. When in Shootout it will have "shootout on the dyno sheet and the dyno sheet must be signed by the operator.

Greg

hopwood

At the moment I am looking at going with Exhausts By Design in Silverstone.

Joel

hopwood

Here's the run with the new manifolds. The blue is the latest run, the red is the one from a few months ago with the cast-iron manifolds.

You can see that the power and torque are down until about 4500rpm, then a significant gain opens up above that.

I will repeat again, the exhaust system is the orignal single-pipe system designed for a 240bhp motor. My next move is to get a custom made Y pipe as per the design on Louie Ott's website, and a 3" system back from there.

Cheers,

Joel

PS: numbers are at the crank (ie corrected). rwhp peak is 242rwhp in shootout mode. I am less interested in absolute power than how the power and torque delivery changes as I introduce mods. I have not seen anyone post before and after with the 86.5 manifolds before.

hacker-pschorr

Absolutely

It would be interesting to play with cam timing now.

I haven't seen anyone post that either.

What did the Y-collector look like on your Euro before this change? Did it have a CAT?

hopwood

No cats in these early 928s over here, they didn't come in until 1989. The front section is a dual in, single out large silencer. Then an intermediate silencer then the single pipe pumpkin.

If the claims made for Y pipes and X pipes are true (seen dyno evidence for X but not Y) then this front unit is restrictive. I also know from personal experience that they don't do a while lot of silencing. If you put a Y on a 79 928 it doesn't actually sound all that different.

Joel

GlenL

I understand that the first muffler on a true RoW "S" car has a cross-over. Anyone cut one open or can otherwise confirm?

slate blue

Joel you are going quite well at 242 rwhp, yours is a 4.7L correct? My engine did a best of 275 rwhp in that guise but there was no tuning at that stage. Are you using S2 manifolds? If so I didn't, I used S manifolds modified to suit the electronic injector. Have you ported the plenum/runners? Mine was ported. Also the ports were tidied up too. The exhaust with headers will be a big factor.

There has been a few 928ers saying they want RHD headers, the easiest way to do that would be to copy mine in Taiwan. They would work out most likely in the $1600 to $2000 range for polished stainless headers without removeable collectors. They would need 10 sets I would guess to make it worthwhile.

Greg

hopwood

Intake manifold is "S" so that we could re use the KJet injectors. I dont think there is a significant difference between the performance of S and S2, its just that the S2 obviously has the holes for the LJet injectors.

Greg, i havent done any porting work on the intake as yet. Want to pick up the low hanging fruit on the exhaust front first.

Joel

mark kibort

There is a big difference between the older S and euro S Ljet or LHjet injector ready runners.

Also, "corrected" in dyno land is not really about crank vs flywheel. that 15% is very estimated and should never be used on a plot. actual vs corrected is the calibration based on atomspheric conditions. (temp, humid, pressure)

I got 243rwhp at a best run at the dyno, with fuel optimized and timing as well. (it was a tired 175rwhp 928 engine with stock US heads never off the engine)
243 was what happened with headers, 3.5" exhaust, euro intake, plennum, runners, but Ljet injection. And, euro 80 cams. stock US heads and bottomend , original.

headers 10hp, 3.5" exhaust, 10hp, intake, and cams, 35hp, tuning with fuel regulators, 7hp.

btw, advancing timing changes lost hp up top, but gained torque in the middle. about 3-4 ft-lbs.

hopwood

Mark,

I think we may be talking at cross purposes. All im saying is that if you look at the difference between the euro S and S2 there is barely anything in it: slightly peakier torque curve and 310bhp instead of 300bhp.

This is accounted for by the sharper cams in the S2 (specs posted above) and a slightly higher CR (10.4:1 instead of 10:1). The runners are substantially the same. The move to L Jetronic just gets you better economy and of course opens up tuning options. My original aim with this car was to get factory S2 performance, now that I have the 86.5 manifolds on I would like to beat stock S4 numbers.

Cheers,

Joel

GlenL

The lower torque numbers are really interesting. I'd expect no difference and gradual divergence towards redline.

Looks like the A/F number is varying in correlation to the power difference. In fact, it could be responsible for a lot of the difference in power and not just the increased flow. The "before" that trends back to 15:1 is bad. The "after" goes low and stays low, but starts a bit higher. Were there any other changes between the manifold swap?

hopwood

Hi Glen,

The car ran rough for a bit (only for first 2 minutes when cold) and went into the garage, but they couldn't find anything wrong with it, and it came back running fine. No other mechanical work between the runs.

Maybe if the manifolds flow better, lower back pressure = lower torque? I'm guessing.

I have just booked her in for a totally new custom 2" Y pipe as per attached pic, and 2.5" single pipe after that. Hopefully that will open up some more gains. Powerspeed of Kent, England are doing it.

Joel

mark kibort

my point was that the US runners and intake is greatly different
Yes, you are right, there are very subtle differences between the two euro versions. 80ish and 84-85ish. yes, a small duration change on the cams, and small compression change . 10hp. right.

the 86.5 manifolds (exhaust) will help , maybe close to headers.

with the Ljet system on there, you basically put a restrictor plate on the euro stuff as we saw. probably 10-15hp lurking there. 290 is what we get, and we think with MAF conversion we will se 300rwhp. (with headers)


mk

mark kibort

as far as back pressure and torque changes. we did the change in steps. nowhere did we see any loss in torque. it always stayed the same, while hp generally went up. headers, gained 10hp. opened exhaust with y pipe and 3.5' exhaust, 10hp. better intake and cams, 35hp, and slight torque loss, probalby due to the cams.

mark kibort

those graphs are interesting, as we havent seen a cast vs 85 ex manifold comparison.
i think the gains are real, the losses are not, in my opinion, due to the fuel ratios, which could have changed for a number of reasons. pump up fuel pressure and this might not be a problem. computers totally up and running warm? I dont know about the euro, but the S4 needs 30min of run times before it gets right.