Carl Fausett

Just received a 1984 928 S - L-Jetronic to supercharge. 60,000 original miles on the car. I will be doing a timing belt/water pump replacement for maintenance reasons, and supercharging it for the customer.

We dyno'd it today to get the "before" chart and to confirm that the Bosch L-Jetronic air-fuel was working properly before the SC install. Look at the chart below - I do not think I have ever seen a flatter air/fuel chart, really exceptional. This 5 spd 928 S is totally stock in every way.

I'll post results after the SC install when I have them. I figure about 4 weeks because I am finishing the 1990 GT SC install and going to SoCal for Sharktoberfest.

Jack '84 928s

I need a 2nd job or something so i can supercharge mine...

PorKen

I can't wait to see the blown numbers!

I'm just happy my poor old '81 4.5, with twice the miles, made similar RW numbers - with an automatic!

onebad928s

quick carl,
you were already offering a kit for the L-jets, is it me or are you just testing them now since if im right this is the first post with the L-jet.

Lou
83 928 5speed

Shane

My sentiments exactly!

Be nice to see all though Ljets running around have some more bite to go with their looks!

Carl Fausett

Onebad -
you are right, we had done all the development for L-Jet and built kits but have not had a L-Jet "taker" before now. We offered a discount (10%) to who-ever wanted to be first, and this customer took it. That is why I am doing the installation myuslef - so if I run into any unforeseen issues I can ressolve them.

At the rate these seem to go - about 6 to 8 installs per year - it'll be a little while before anybody can say they have previous experience with every year, fuel system, compression ration, 2v/4v setup. In each make and model year - there is always a "first".

We will be putting 6 psi non-intercooled on this engine and our research with Bosch and the good help of 2v4v in our shop makes us believe that it will fuel at 5 psi with no modifications. At 6 psi (our goal on this project) we may have to add a FMU. That's why its here (the customer brought it here from Maryland) - so I can make sure it is fueling right before he gets it back.

bshaw

Power seems a little low, dosen't it? Mine did 210 hp, 261 ft/lbs on the Dynojet before I SC'ed it. Now 265 hp, 284 ft lbs on 5 lbs of boost.

toofast928

Bill are you sure of your #'s? You gained 50 hp and 23 ft lbs?

Tony--

Carl Fausett

bshaw - I agree, seems about 10 HP off from what I expected. I know this Dyno to be very accurate with other cars, so I do not think that is it. 60,000 miles on the car, pretty well taken care of, timing belt replaced 2 years ago and I wonder if it is off 1 tooth... or the spark plug gap is to wide... or the compression is weak somewhere.. somthing is amiss. I'll look into it.

hacker-pschorr

Carl - just an FYI about the power of this car. My car has good compression, new plugs gapped correctly, all nuw vacuum lines, plug wires, cap, and rotor etc..... At the dyno in Manitowoc, it put down 160rwhp. That was the same day Murphy's stock S4 did 260 and his Murf928 did 550+. Friday Jim Page is going to assist me in checking cam timing.

So in Green Bay we have the highest known dyno numbers for a 928, and the lowest.

bshaw

Hi Tony,

Yes, I'm pretty sure of the numbers. Both runs were on the same dyno and plotted on the same graph. I'm not sure what Quick Carl had before OCIC, but my SC'ed numbers jive with the results of his post-SC dyno run there.

BTW Carl, both of my dyno runs showed an AFR as flat as the one above. L-jet does a pretty good job of controlling the AFR, as does the '749 when all is right.

Scott M.

Carl;

Your 84 car seems to be about 20hp/25tq lower than comparable 84 cars. Check out the dyno runs post of a few days ago for comparasions. Might I suggest you re-dyno this car after you find it's missing numbers, before you SC it. Honestly, I have a somewhat vested interest in you work and in order to be truely unbiased in the final product I would need more factual readings. Pre and post.

Good luck w/ the install.

Scott

Jim bailey - 928 International

The old very brown 1980 dynoed 188hp -221torque (edit) Keith Widom's car was virtually identical same day same dyno ......they are 4.5 engines. The 4.7 should have maybe 10 hp more, not much you might check ignition timing.

PorKen

I think Jim meant to type: "188hp -221tq"

Over the course of many dyno sessions, I scored ~190 RWHP and ~220 RWTQ (stock cams and exhaust manifolds).

Side note: I run my cams ~3 degrees advanced, which the dyno showed a trade of ~5 RWTQ for ~5 RWHP, and moved the peaks lower by ~600 RPM.

Carl Fausett

Progress photos... its coming along...