hopwood

Car is a 1979 Euro with Euro S2 310hp motor (sharpest cams and Euro intake obviously...) running with the K Jetronic injection and the original dissy. So I guess a hybrid of non-S, S and S2 parts. I still have the original single-pipe Euro 79 exhaust on there too.

Just had the car serviced and fixed by GT One in Chertsey, Surrey (England) who come very highly rated and have done a fantastic job. After a long tale of woe involving a previous shop not tightening up the head bolts after "rebuilding" the engine... leading to head gasket failure etc etc etc

ANYWAY, I picked the car up from this new shop, and Oh, My, God... they did warn me that there would be a significant difference. Turns out, as well as everything else, the vacuum lines to the WUR and dissy were misrouted, meaning the timing was completely out.

It runs so well now, I can't believe I ever thought it ran well before. It made 318ft/lb and 287bhp at the crank, 237 at the wheels. I figure since Porsche moved to a totally new twin pipe exhaust for the S, there is still some power left on the table though.

My next move is to fit the 86.5 manifolds and have a custom exhaust back from there. I'm figuring 2.25" y pipe into single 3" all the way back with resonators and large rear silencer. I was going to use the angles specified on Louie Ott's website for the merge collector.

All thoughts welcome.

Joel

GlenL

I think your number and analysis thereof are spot on. With a better exhaust you should be very close to 300 BHP.

I would like to see the A/F numbers. Have you added any advance to the distributor? 3 degrees are worth 5-10 HP.

Hilton

Glen, looks like AF is on the second graph?

Congrats Joel! The new exhaust should wake it up a fair bit too, and improve breathing at the higher end (AF looks like its having trouble getting enough air through the engine).

Of course, once you have the early 32V manifolds on, you're going to have to find another upgrade to do... didn't someone modify some MSDS headers to fit a RHD car? Nick Scudder maybe?

GlenL

Gol durn it!

Looks like there's not enough gas after 3500 RPM. That's holding you back. It should be flat to trending down. 12.5:1 gives more power but is smelly for the street. 13 at 6000 is a good target.

I'd look to a new fuel filter and cleaning the "secret" screen at the inlet to the fuel distributor.

Iwanna928

Nice Job! It is fun going to the dyno! I am sure you had fun, and there is such a nice feeling knowing your car is running well!

Maybe I missed it but is your car an auto or a stick?

AO

Spectacular!

Hilton

Its a "stick"

You can read about it and see it in this thread:

https://rennlist.com/forums/928-foru...ports-car.html

Glenn Evans

Check your fuel pressures. The control pressure regulator aka WUR should enrich the mixture to 12.5:1 at wide-open throttle and give you more power. This is not "smelly on the street" unless you have the accelerator permanently firewalled!

A K-Jet 928S on a local dyno produced a perfectly flat air-fuel ratio of 12.5:1 throughout a dyno run I witnessed a couple of years back. None of the LH-Jetronic cars produced an AFR anywhere near as steady and flat. (Score one for old tech!) :-)

mark kibort

thats pretty good. when you think of it, scot did this kid of run with his 5 liter version (albeit with a US Ljet) sure its a little lean, but what was the source of the test. tail pipe? calibrated lately? could be off, and you might be ok. how do the plugs look? I remember going from tail pipe to sensor in the cat pipe giving two very different readings.

GlenL

Apparently we're different people.

Mine's tuned for power with low A/F and it is toxic in the garage.

Mines like this. Actually remps down to 12.5 at 6000 rpm from 13.5 at 1000.

Rebuilt fuel dist and WUR doing good work.

V2Rocket

+1

hopwood

My fuel pump started making a really funny noise the other day, a rhythmic sort of judder, about every 1.5 seconds, accompanied by a jerk in the power. So I have a new fuel pump from Bosch on the way, hopefully this will also help.

Thanks for the pointer on the filter and secret screen. Is the screen difficult to access?

Joel

GlenL

It's part of a male-male adapter at the inlet to the fuel distributor. Not hard to get to once the air box is off. It's on the left side of the distributor at "10 o'clock" pointing roughly towards the left front headlight. The supply is a fatter line than the return.

Hilton

Hope you changed the fuel pump relay first to see if it persisted

hopwood

OH ****! Is it a standard 53?