123quattro

Car is stock US 84S 5 speed except for MSDS headers and a 3" exhaust into a Magnaflow muffler. I took it to my buddy's shop and we made 4 pulls. The first two it was surprisingly lean. Somewhere around 15:1 at WOT. Following that I checked the WOT switch and it was functioning. So, we messed around with the fuel pressure regulators and got the A/F ratio down to 14:1 at WOT. I'd have liked lower but that was the best we could do with at the time.

Anyway, here's what it did with more fuel.

226 wheel hp @ 4600
277 wheel ft-lb @ 3600

I was originally going to increase the timing as it was stock numbers, but wasn't about to with the fueling problems.

So....I need to get quite a bit more fuel into it as it stands, and the Euro heads/cams going on this weekend will only make that worse. I wish I had the time to get the Haltech on it prior to going on Powertour, but that's optimistic since it starts in three weeks.

SharkSkin

That's pretty decent -- no baseline with stock exhaust?

Fogey1

+1

will
83S

Mongo

Keep your dyno sheet until you get an aftermarket EMS. Have you checked out Carl's Electromotive? I'm going his TecGT route after the house, wedding all that other girly sh*t.

al83s

Which Haltech you going with? Im thinking of installing aftermarket EFI on my 83S Euro

123quattro

I have a Haltech E6k I'm eventually going to install. It's an old model but the price was right (free).

I did not run a completely stock baseline. I only ran it this time to see what adding the heads/cams got me.

mark kibort

my best numbers before the euro stuff was 200rwhp, but it was a very tired 84 US motor. It did last for another 50,000miles and lots of racing until the head gasket went and leaked water out in to the valley, which for another year, barr's stop leaked controlled that!

Now, you need to clamp down the second fuel regulator, and turn up the other regulator. there is no way you cant get the fuel in the 12s. How do you know you know you are not there now? what does the fuel look like? should be flat and slightly lean at the top. tail pipe readings can be off a little. I put on the cams and euro intake and it went up 50hp, while the fuel was constant. still in the 13:1 range. we tweaked that to 12.6, going as rich as 12:1 and backing off a bit to make it just about perfect. So, the system can handle it.

what regulator do you have? do you have 2 of them, or just one? How did the plugs look? tail pipe ?

the only BIG gains after euro stuff will be to rid yourself of the AFM. we can discuss that later.
fuel and spark can be adjusted for WOT performance, so no chip or aftermarket ECU will do very much.
the MAF conversion will do the biggest gains and existing stuff can be used for that tool.

mk

123quattro

My car is L-Jetronic and has the multiple regulators. Pretty sure there are 3. One into the rails, and one on each outlet.

http://www.928injection.com/

We had a wideband in the exhaust. I believe the numbers we were seeing. It was relatively constant A/F, but leaned out around peak power and then dropped back down after that. Adding fuel in got us 20 ft-lbs across the board.

The AFM will go away with the Haltech as it uses a GM MAP sensor.

Mike Frye

I'm sure the wideband would work better with a bung installation, but if you don't have cats on there (which it doesn't seem like you do) the tailpipe sniffer should be pretty accurate, especially if it was consistent and not erratic at all.

123quattro

To be fair, the wideband wasn't really measuring the numbers I said. It reads about 0.9 A/F high over what's real. He has confirmed that offset with real readings taken simultaneously with collector and tailpipe measurements with a second wideband.

And you are correct, I have no cats. The 3" collectors come together into a Y merge collector that's 3" all the way back afterwards.

RicerSchnitzzle

Headers and exhaust for an extra 30-35 RWHP, sounds about right. Nice!

Cosmo Kramer

Good numbers for a US 16V, nice work!

You are making me want to put an X pipe on my 32V!

mark kibort

No, the 84 928 has 2 regulators and one damper up front on the engine.
So, it begs the question, how were you regulating fuel? If you have two RRFRs, did you crank them up all the way? Probably not. Like i said, ive done a few of these systems and it is very easy to get any fuel ratio you want up to about 300rwhp. so, if you are not seeing it now, something else is going on. If you noticed from our improved 84 Ljet system, we use ONLY one RRFR and clamp off the return line from the driver side stock regulator. you can do this today by only taking a vice grip and slowly clamping down the return line (the one that has the rubber hose connected on to the bottom of it, opposite the vaccum line) then, fit the return line hose back over it, so that the little fuel now that is leaking out, can go where it normally would go anyway. (no hard mods and it works great) now, your regulation is done with the single regulator and will raise the pressure and fuel ratios about 1 point.

mk

123quattro

Mark, I put 10 psi of air pressure into the vacuum reference on the regulators and damper. All three have their vacuum reference tied together. It worked well for a quick and dirty fix on the dyno.

PorKen

The easiest way to enrich the mixture with L-Jet is by adding resistance to the Temp II input.

I would suggest using an extra WOT switch for a two stage resistance, a little extra for cruising/idle, but within the range of the O2 loop, and more at WOT.


L-Jet's 24# injectors will support 300+ HP, even at 2.5 bar. (S2/S3 LH-Jet also use 24# @ 2.5bar.)



I used a 20K resistor, added to the TempII sensor resistance, to delete the cold start injector on my old '81, using a reed relay triggered by the thermotime switch.