Rob Edwards

There has been a lot of talk lately about community on this board. Before I bought my 928 I had been lurking on Rennlist for a long time and part of the attraction to sharks was the infectious enthusiasm people brought to this discussion group. I bought my GT almost 3 years ago because I figured I’d need all the help I could get keeping the car in one piece. I also intended to keep the car as stock as possible, partly for cost/resale considerations, and partly for stealth reasons.

Well, so much for stock. When Mark A announced the 50% off sale in December, I decided to take the plunge. This way I can keep the stock motor stock and unmolested, so when 928's skyrocket in value I'll have the 'matching numbers' motor for the car.... The original intention was to buy a 5 liter motor half off, then build myself a stroker. Mark had a Scat crank and some 944S2 pistons, gave me the number of a machine shop in town, and I’d just toss it together and all would be great. Well, that plan lasted as long as it took to go home and read all the threads on this fine board regarding the amount of minutiae, thought, and skill that goes into doing this right. With 3 small kids, limited time and eyes that glaze over at the mention of things like 'lobe centers', it quickly became clear to me that I’d never get anywhere doing this myself. Then I completely lucked into a ’91 GT motor that was hiding in an ‘89S4 auto with 200+K miles on it. So I decided to take a different route.

I am fortunate to have 928Intl and Precision Motorwerks in my backyard, and so I approached Greg Brown with a modest proposal. Greg has invested a lot of time and effort into the minutiae of what works and what doesn’t’ work. And I have discovered that I am good at taking things apart and cleaning and generally doing garage monkey scut work. So- the overall plan is this: I do as much of the monkey scut as I can, and Greg does the skilled labor and design. This way, I end up with a Greg Brown 6.5L stroker motor, I spend a couple of Saturday afternoons in his shop learning some 928-specific wrenching skills, and in the end I save a bunch of money on labor. While Greg is working his magic on the longblock assembly, I will pull my old motor, prep the engine compartment, swap all the accessories, clean hardware, etc. Then I will install the longblock, button everything up, and then take the car back to Greg for some pre-fireup idiotproofing and then tuning. A win-win, as far as I’m concerned.

This all started by my ‘helping’ (I use the term loosely) Mark’s son Scott extricate the GT motor from the donor car just before Christmas. I put down a deposit with Greg for a crank shortly thereafter. Things have progressed much more quickly than I would have predicted (there, just cursed myself) and since we just passed the milestone of having all the major parts in hand, I thought it was time to start a new stroker thread.


Of course, stroker building is an evolutionary iterative process and so there are a few new things that we’re trying on this motor. At this point I have no idea what will work and what won’t, but part of the fun is seeing what I end up with. Some of it is probably absurd for a street motor but what the hell, life is short. I am keeping tabs on costs but if you need a ballpark, just today Carl has conveniently listed a price list that is for all intents and purposes a line drive right up the middle, to continue the baseball analogy.

I will also try to relate as best I can what we are doing but remember that some of the eleven herbs and spices are trade secrets! I make my living in a field where we all depend on each other to be entrusted with proprietary research data, and in that sense Greg's job and mine are exactly the same.

So consider this a placeholder for regular updates and progress reports. In the spirit of community I am tentatively looking to have an engine pulling party somewhere around the second week of April in order to have the car ready for the new motor. There is far too much beer left over from Luan's Porkensioner seission..... I never could have gotten this car to its current state without this community and I hope to give something back, if nothing else by providing some vague entertainment here on the board.

In the meantime, I thought I’d post some engine **** just to get things off to a start.

Stock ’91 GT piston with a 104 mm stroker piston:



Stock ’91 GT forged rod with a Carrillo H-series rod:




GT vs Moldex stroker crank:



Comparison of Stock vs. stroker rod journal offsets:
Stock (pickled in Lithium grease):

Stroker:



And some random engine shots along the way:

The donor motor coming out:



Mark Anderson hard at work on freeing the engine harness by the ABS pump:





Greg: Rob, heat the block before turning out the studs.
Rob. Ok.
Greg: Propane is for lighting cigars, use acetylene or at least MAPP gas!
Rob: Ok.
Rob: (Afraid I'm going to melt the block, didn't heat enough) Oops:


Greg to the rescue:



Heads, previously re-surfaced by dragging them down the street:


Lifter surface polishing:


Clean engine castings ('83 oil pan on a '91 GT, wonder where that came from???) :


Shiny bits:

MGW-Fla

Looks like a fun project. You are especially fortunate to have direct access to learn from the skills of GB & MA. Good Luck!

CAShark

Yikes, shiny bits on wifes kitchen counter, you are brave.

Tom. M

I don't know..that wallet doesn't look fat enough to sustain the cash withdrawal rate required to build a stroker ... But perhaps the bottle of Remy might help ease the pain ..

Congrats..look forward to more updates...

dr bob

Rob--

That stroker crank makes a darn nice living room decoration. It's almost a crime hiding it inside the block. I'll bet that Jen doesn't share my aesthetic standards though.

The 'old' motor is too tall to be a coffee table with the intake installed. You'll need a slightly bigger dining room to put it to practical use.

I also dare say that there's still a good chance for a lift here before mid April and engine swap time. Don't know if that helps you any, but you are always welcome to whatever is available here. My neighbors, the lions and tigers and bears where the deer and the antelope play, have a much higher tolerance for extended wrenching. Plus there's a bit more space. But it's further from Greg. But we'll need a trailer anyway. But the hill is steel and the driveway and street are a little narrow. So peg your dates and I'll be wherever you need me.

BC

I'd be delighted to partake in an engine pull around your project Rob. I have done it... A few times, and I'd like to see it done right for once.

Rob Edwards

Brendan-

You've seen my skill with painting calipers, installing motor mounts upside down and snapping engine studs. What makes you think I'd pull a motor correctly?

BC

Its much easier that putting anything together! Just a few big and small bolts. And then... Pull!

RyanPerrella

thats exactly what i thought, that is a really nice piece!

Rob Edwards

It is industrial art. There's not a surface on it that hasn't been attended to- it makes the factory crank look like a crude piece. It's also a lot lighter than the factory crank. I don't think Jen would approve of my redecorating plans, though.

RyanPerrella

what does Greg think about knife edging the cranks? I kinda thought the Moldex would have this. I was considering doing it to a crank that I would have drilled.

ShawnSmith

Welcome to the party!

I'm using my original starter as a doorstop since it had to be replaced with a smaller one...

So far, the wife has not caught on to the stealth parts-storage operation creeping into the house.

Rob Edwards

Yeah, not sure what I'm going to do with 1.5 engines' worth of spare parts. Maybe I'll open a Porsche-themed TGI Friday's and have lots of 'flair' on the walls.

Ryan- I have no idea about knife edging, I would imagine the crank probably needs all the mass it has left for strength (?) or balancing (?)

GregBBRD

greg doesn't think it is a good idea, for several reasons: Here's a couple that are really obvious:

When the mass of the counterweight is reduced, especially on a small counterweight like is required on these relatively short rod engines, the only way to bring the engine back into balance is with the addition of Mallory. The addition of Mallory makes the crank much heavier and is very costly. Plan on adding 1,000.00 to 1200.00 dollars to get the crank to balance. This makes the effective "cost" of knife edging the crank much higher, which is certainly not calculated into the overall costs of an engine, by rookies.

Given the "real" cost of knife edging being close to $1500.00, that is not a very good return for the small amount of benefit to be found in these relatively low rpm engines. Since all engine projects have a budget, of some sort, I find that I can better spend that amount of money in another area that will give a better return.

Even on a "no budget" engine, the benefit of knife edging has to be weighed versus the increase in required mass away from the crank centerline. I've spent a lot of time and effort getting pieces as light as possible and have to think very hard about making something heavier, away from centerline.

I have to smile at the people that "think" they can do this stuff. While I think that "mirroring" my engines is the best form of flattery, there's a whole bunch more to this process than writing words on a piece of paper. All one needs to do is review the "experts" that have failed at attempting to do these engines. I've been doing 928 engines for over 25 years and I'm still learning....how someone can come along and hope to do this stuff, without knowledge and experience, is beyond me.

dr bob

Greg, would you mind if I borrowed that last paragraph and polished it a bit for the work I do? Maybe it will be on a poster, nice frame, one of those inspiration messages you see hanging on the walls of the illiteratti, folks who can't read the message.


Might look something like this: