XS29L9B

Found while cleaning the basement this weekend. Pretty cool find!!

hwyrnr

$18,500 for turbos back in 84. Geez a very costly upgrade back then. Heck that's costly today

The Forgotten On

And the turbo 928 was still slower than a stock Euro S. Oh how far we have come....

XS29L9B

The C/D numbers show it faster than whichever they compared it to (928 to 928), and I would be surprised if it were slower than an Euro 928s, also.

ptuomov

Nice article. I think these turbo systems were rated with a certain boost pressure and then there was an expectation that wastegate and boost controller “adjustments” would be made by the user...

GregBBRD

I was actually around and very active with 928s in 1984.

Try to keep in mind how crude fueling waa and what "tools" were available to change said fueling (if you weren't Bosch,) at that time.

That factor, alone, was very limiting, for everyone.

There wasn't very much "micro" in a Callaway micro fueler.. Better than a 5 gallon pail of fuel, sitting on the hood. with a hose running to the intake, but not by a whole bunch.

ptuomov

Long before my time, I admit! ;-). Still, human nature remains the same and it’s not possible for a live red blooded human to not turn that screw up until the ring lands give up.

GregBBRD

Yes, fixed one with broken lands, way back then.
Those cast pistons don't take much abuse.

ptuomov

In my experience, the 100mm S4 piston can withstand almost any sort of abuse that any piston can -- except rpms, because they are so heavy. The ring lands are thick and the thermal inertia of the piston is huge. It's like a modern turbo diesel piston with its massive wrist pin, huge ring lands, and full skirt that is built for gas pressure much exceeding anything that any normally aspirated engine can produce. In my opinion, a great design for a turbo engine.

The three counterpoints to this are: First, as already mentioned, the S4 rotating assembly overall really isn't built for high rpms in many ways. Second, if one lets the engine to overheat then some problem will surface at some point. Third, no piston, forged or cast or whatever, can withstand extended periods of high-load detonation. S4 pistons will give up for sure if you throw any amount of boost at them _and_ allow the engine to detonate either because ignition timing or fueling are not set correctly. But so would a forged piston, too.

A lot of people automatically assume that forced induction engines are the ones that require forged pistons. By my thinking, the reality is 90-degrees different. I think that it’s high rpm engines that need forged pistons, whether they are forced induction or normally aspirated. Forged pistons are stronger _per gram_. They aren’t automatically stronger than heavier cast pistons. In a low rpm engine, you can just make your cast pistons a little heavier and they’ll last for a long time. In a high rpm engine, you can’ti make the pistons a little heavier because weight itself causes the whole rotating assembly to be less reliable.

NickTucker

That is indeed a cool article.. Amazing how far he has come as well as the cars..

XS29L9B

Saw this pic online today. From the location in CT
Silver car is the 254.76 mph Callaway Sledgehammer from 1988
Purple car is 1991, so same era as our cars here.

Mark Anderson

Many many years ago i had a customer with a 1982 Calloway 928 and after his second engine he came to me looking for options. I installed a 1989 gt motor in it and he swore it was faster than the turbo ever was. Installing that engine back then was a huge undertaking for me. We also stuffed 315 rear tires on it with some custom Gotti wheels.

Catorce

I agree fuel was a limiting factor back then. You should have seen the black mystery boxes that came off the Devore car that he adapted to trim the fuel curves with. It was state of the art back then, but that isn't saying much.

XS29L9B

The Microfueler is a pretty interesting box, and can control one or two additional injectors. I believe it depends on the version of the MF box.

Anyways, I know someone who changed their MF to a "modern" system and the car did run even better, but no surprise, as the "brains" of the controller have gotten better. Like a Commodore 64 v. Macbook Pro. Anyways, the MF was simple and worked. But as agreed (I think), time marches on and even better auxiliary injector controllers exist.

Heck, I remember something for Turbo Buicks (parts released) in the 90s which was very crude, especially compared to the MF.

ptuomov

Let's just say that John Kuhn is not a fan of that Calloway system...

The 89GT engine in a 1982 chassis is a legitimately fast combo, especially if the exhaust isn't completely stock.