Originally Posted by Constantine

But not anymore thanks to John Speake!

Originally Posted by John Speake

One advantage of the PEMs is that they allow you to simultaneously data log all LH and EZK parameters.
Jim used this facility to great effect !

Originally Posted by Sterling

Dennis,
What are the chances of getting Elgin to do another set of these cams.... and just out of curiosity do you have the cam Dr docs on the cams so they could be duplicated somewhere else if elgin isn't interested?

Originally Posted by Dennis K

Six months and 5000 miles after the first start of the motor, it’s time for an update. From the first time this motor went WOT, we knew it was strong. We weren’t sure exactly how strong, but if you can get Bill Ball to cry “uncle” during an acceleration run, chances are good you have a beast on your hands. Now we’ve been able quantify just how strong this thing is.

Recapping the specs, this is a stock displacement engine with stock 5.0L ’91 GT pistons, connecting rods and crankshaft. The rotating assembly was re-balanced. The ’88 S4 heads have the stock S4 intake and exhaust valves, no porting or polishing. The heads have been shaved 0.020”. The intake manifold is stock and does not even have spacers. The airbox is stock. A post with all the specs for this motor and a few pics of build is here.

Since the main goal for this engine was reliability during track use, there has been a lot of work that has gone into the oiling system. The crank has been drilled, an I-J crank scraper kit has been installed and the oil pan has been spaced 3/8” down. If you want to learn more about the drilled crank, I wrote a post about it last year here.

Essentially, the cams and the headers are the two major performance mods. The intake and exhaust cams are from ’85-’86 S3 32V engine and have been modified by Elgin Cams. The driver’s side exhaust cam has been modified to fit the S4 heads by extending the bearing area at the front cam cap. All the cams have been reground by Elgin w/ a smaller base circle for greater duration and lift. The base circle difference is slight enough that no modifications were needed for the lifters and no lash caps were needed for the valves. We took great care to make sure these cams were timed accurately, as you can see here.

This type of approach was typical throughout the build. Jim Morton had the Cam Doctor files with the exact dimensions for these cam lobes. He was able to precisely determine the dynamic compression ratio and even model the airflow for the engine. I have dozens of Excel workheets where we measured & calculated things like bearing clearances, fuel injector sizing, cam timing, piston speeds, etc. We never took any piece of data for granted, whether it came from a sensor, from the internet or from a vendor. We tried to confirm everything as much as possible so we could make informed decisions as we went along.

Since the engine was built, we have been using Jim’s Sharktuner to bring the engine into tune. We’ve been learning together how to use this powerful tool (which has generated yet another raft of Excel worksheets). We started out doing full throttle runs on the freeway, trying to gather data and make appropriate adjustments to the various fuel maps. We found out quickly that the throttle position sensor was bad and then later that the old re-installed MAF was faulty.

As of late we have been using the Mustang Dyno at Holleran’s Performance in Pinole, CA to do our tuning. Over the course of 40+ dyno runs over three days, we’ve been able to log data via the Sharktuner and a Techedge wideband O2 box. We’ve spent a lot of time sorting through all the data to come up with revisions to the fuel & ignition maps. Once we had the air:fuel ratios controlled throughout the rev range, we have tested various AFR's, flappy actuation rpms and ignition timing mods.

So here are the results from our latest dyno session (these numbers are at the rear wheels):


Here's a comparison of the engine in its untuned state (first dyno run, first day) to where it is now:


Here's one of the Excel charts I spoke of, showing the AFR & ignition advance:


And here is a video I made from our second dyno day. (We’ve gained a little hp & tq since then.)


To say I’m overjoyed with this result is an understatement. I can honestly say I’ve enjoyed every minute of this build. (aside maybe from paint stripping the intake manifold & cam covers, that kind of sucked) Seeing these numbers has made everything absolutely worth it. I’ve had two months to digest the data and I still can’t believe it. Even with this level of performance, there is no compromise in driveability. All of these runs were made on plain CA 91 octane gas. The car idles completely normally at the stock 928GT idle speed of 775 rpm. It even passed a CA smog check a few months ago with a slightly different exhaust:


In closing I have to thank my friends Jim Morton & Bill Ball once again. The genesis of this project was the seizing of two motors in two track days. I was seriously considering moving on to racing Spec Miatas but Jim & Bill reeled me back from the abyss and offered me their help to build this motor. They’ve been good to their word and have gone far beyond any reasonable expectation of help. Jim has spent an incredible amount of time to engineer the result you see here. Bill has been available at every single opportunity to work on this motor. His only questions are “where and when?”

We’re out of fuel and air to make any more hp improvements . . . for now. The story isn’t over yet though. Currently, we’re prepping the car for a track day. In a few weeks I’ll be able to post some video of this motor being exercised at Thunderhill.

Originally Posted by Dennis K

That reminds me of another Sharktuner tuning mod I forgot: we raised the rev limiter.

Originally Posted by mark kibort

some tuning

Originally Posted by Hacker-Pschorr

"Some" tuning?

That is like saying the Hoover Dam is "some construction"

For the love of all things fast, please hand your car over to someone that knows what they are doing with the Shark Tuner. Please?

Originally Posted by mark kibort

yeah, some tuning. The shark tuner is doing what real racers and their engine builders have been doing for years. The BMW and others have the timing of the individual cams to adjust too. (adding another dimension to the process) The nice thing about the shark tuner, is the ease of how it does what it does.

we have already done some changes to my liking in the tuning area. We retarded the cams and lost 20ftlbs of torque and extended the HP curve. Ill probably get 98% of the power at how i use the car by optimizing fuel. Remember Dennis was adjusting full throttle, part throttle and idle . I could care less about how it runs, as long as it runs! actually, it runs just like a street 928 now. Ill i need is some optimization from 4500 to 6500rpm with fuel and that should be reached by some leaning out of the mixture. I'm probalby close now, but the dyno will tell the results. What ever I have done, we have no idea what its doing at the track. did you see my last video? Im pulling on guys with 520 to 550hp with the comp coupe and Camaro, as well as running away from the lighter S2000 SC with 390rwhp. Something is working pretty well as it is now , and probably better on the track that what is shown on the dyno.

I dont know what Dennis gained by adjusting spark the second wave of tuning, but i would guess it was not much. Sure every little bit helps.

Back to "Some Tuning". I would have to say, yes. He has no idea what that car is going to be doing on the track over a 30 min race, at temperature ranges from 40 to 110degrees F. He has done most of the work, but tuning is a process not a destination. you think these race teams just do a dyno and do a tune? They are constantly on the dyno optimizing and improving. There are still a ton of variables and possiblities in changes he could do now. That's not to take ANYTHING away from these spectacular results, but what Im saying is the S4 system is pretty darn good in pure stock form with a few tweeks. As was seen, Dennis was at 350HP with out any tuning at the start of the process.

mk

ps dont forget we are missing the diagnostic port, so we cant check some of the performance real time like Bill and I wanted to do.

Originally Posted by RyanPerrella

I honestly dont think its THAT EASY as you suggest.

Based on what ive heard it sounds like Jim made it a personal Mission with all the data they collected. So i have to imagine more then just SOME TUNING went into that thing. I imagine there are truly countless hours getting it there. And i am sure Jim has a much higher lever of comprehension about the ins and outs of complete engine mapping, the likes of which i will probably NEVER understand.

Maybe someday when i have some killer motor, i can borrow Jims brain for a bit.......