Aspkiller

This is a new thread that came about when numerous ADDICTS were posting info and thoughts about 928 strokers and others were posting info and thoughts about Chevy engines (particularly LS based).

I had an '82 928 Auto siting in my garage that was no longer being driven by my wife. It sat for more than 10 years. One day I decided to get it running and discovered that it needed a tranny rebuild, all new harness, fuel lines, injectors, etc etc etc. That's when I started to think about a Chevy conversion.

I then decided that I would Open Road Race the car, but why do it with an '82. Let's get a '91 GT. I could put an LS Chevy in the '91 and put the '91 engine in the '82. Made perfect sense to someone who didn't know any better. So I got the '91 GT.

One of the first things I did was get in touch with Greg Brown to discuss doing the swap. GB wasn't at all excited about the issues associated with putting a GT engine in the '82. So, I scrapped that idea.

During my discussions with GB, I asked about the price to build a 928 "RACE" motor with a high degree of reliability and could produce 600-650 crank HP. I have yet to see a number that approaches the number I remember him quoting.

I quickly decided to go the LS7 crate motor route, as supplied by Turn Key Engine Supply. Another uninformed mistake on my part. Chevy crate motors are NOT race motors. Quickly spun a bearing and later poked a hole thru the LS7 factory head when we fly cut a spring pocket and got into a water jacket casting flaw.

So, now I'm back on the race track with an almost totally rebuilt LS7 block and very little else that is factory LS7 (Calley rotating-Daley 5 stage pump and pan, T & D rockers, etc.). Had we gone directly to this motor, I would be in it for about $30K using a top notch engine builder. Output is north of 600/600 at wheels on 110 leaded with optimum tune and shutting down at 6,800. A little more air intake and the numbers go up. The motor will easily spin to 7,500, but we shift at 6,400 routinely and occasionally 6,800. I also run it with a little less timing and a little bit fat, as knock sensors won't work in my motor.

So, I think there are a lot of RListers who would like to provide similar info about their motor experiences, specifications, output numbers, and costs.

Anyone?

genikz

Subscribed.

I'm slowly (!) building a '78 track car, and while still using the factory engine, am interested in alternatives when the time comes.

My limited input: in my experience in talking to guys with LSx motors at the track, they have been on their (at least) 2nd engine in the car. Most resorted to buying a used motor as a replacement. It seems they prefer the cheaper method of grenading them, and buying used to grenade again, rather than spend the coin to try to build a bullet-proof one.

Aspkiller

Sadly, there is no such thing as a bullet proof motor. But, we keep trying.

bcdavis

If you are building a street car stroker, it makes more sense to build a 928 motor, build it right, and it should last the entire time you own the car.

If you are racing, it seems a lot more likely you will eventually need to rebuild or replace the motor. Doing so will be cheaper with a SBC. Lots more parts, mechanics, machine shops, etc. With the 928, you pretty much have only one source for good stroker motors, maybe two, and the backlog and cost is extensive.

Mike Simard

It's nice to hear about your experiences, thanks for this opportunity.

I would never put my engine into a cost number although seeing some of the big numbers given for chevy race engines made me think I could build more of my own!
Part of my not putting a dollar value on it is becasue it's a personal creation of my passion. It would be like asking an athlete what it costs to become the way they are. It's not a shopping item, it's my love!

When I first built my racer it was a proper chassis with the stock 4.5. After all, you can either build a chassis or an engine but not both at the same time.

I parked my fresh 928 racer next to a buddy's 944 LS powered racer. The cars were nearly identical in preperation. Both gutted shells with similar cages and equipment. Yoyu know what the assumption would be for weight, right? I've had guys look me in the face and tell how amazingly light there 928 was after fitting a chevy because the front end sat higher Well my car was 20 lbs lighter than his 944/LS.
As soon as I got the car sorted, in went the new 427 engine and thus gave me an eternally sorting race car which is not good.
I think I finally have it sorted and it's wicked fast, if it has tires.

Here's how the engine compares to a Chevy and the best things about it:
It's 427 cu. in. and has 4 vlaves per cylnder, central spark plugs and overhead cams.
It needs only 10.5:1 to make 700ish hp.
The plug location is ideal and it runs well on 93 octane with no detonation at all.
It revs to 7700 rpms and I often let it flale against the rev limiter with no ill effect. No pushrods to worry about. No bearing issues seen on teardown.
The 928 is basically a big block so it's oversquare with a conservative rod/stroke ratio. The LS7 titanium rods see less g-forces in my engine because of the shorter stroke.
My cylinders extend deeply and the piston skirt doesn't protrude at all which is a huge benefit over a long stroke engine based on an old block like a SBF I once had. Those are dirty engines with blowby and detonation.
Having ITBs means that intake reversion is no longer a problem, a big cam behaves tamely when driving on the street but yet allows big top end power.

So there it is, why I love my Porsche race engine. It's a conservative, big power engine that can be driven around in a heat wave on the street with no trouble and good manners. It's actually a shame to waste it on a race car and maybe we should all be driving spec Miatas and leave these creations as wonderful creations.

GregBBRD

Larry:

There's no debate that the Chevy engine is probably more capable, probably more reliable, and cheaper than a Porsche 928 engine.

Hell, Porsche built first 12 cylinder engines and then 16 cylinder engines to compete against the Big Block Chevy engines that were run in the Can-Am Series. That program cost literally millions of dollars......and I'm sure that Porsche knew that they could pick-up a complete Big Block Cam-Am engine for way less than the mechanical fuel injection pump cost them....much less the entire engine.

I've been trying to figure out how to explain this to you....and it is really tough when all someone wants is fast....as cheap as possible.

Here's my best try:

I just got back from the Porsche Rennsport Reunion at Laguna Seca. There was literally a "sea" of 962s, 917s, Cup Cars, GTs, new RS Spyders, etc.

Not a single one had a Chevy engine in it.....and I can guarantee that some of those engines cost multiple hundreds of thousands of dollars to build.

Why not?

I'm guessing that you really know the answer.

Mike Simard

That's very wise and should be pounded into guys like me. We need some common sense reminders.
Racers are either in it for the racing or for the car. I started by autoxing when young and am now doing what used to be a dream. I really wish I just had a spec car and could keep the creativity out but i can't help it and wind up with unclassable freak cars, in autoxing I always wound up in mod with no competition but my most memorable event was when my pos broke and I had to borrow a normal car from a busy class, with actual intense competion!
So now I'm "in it for the car" and have little close competition and am always sorting. Sigh.

DR

What would be more interesting IMHO and would help the discussion is,

A - How many 928 Race engines are there running in races now (real races, not DEs)?
B - How many have actually ran in a race for a full race season(again, not a DE)?
C- ...and for how many races/miles or laps between rebuilds (voluntary or mandantory)
C - Since 928 Race engines seems to be sort of a generic term, how many were stock internals and how many were aftermarket internals, i.e strokers, modified cranks etc.
D - Of these modified (not stock) Race engines..were they "professionally built" or "owner built".

Without this type of data this thread is sort of useless to those that may be considering now on in the future what is best for them, isn't it???

Off the top of my head I can only think of 2 928s with "real" Race engines that have been campaigned for more than one season, Mark Anderson and Joe Fan? I am drawing a blank, who are the others? I know I am missing some over the last 15 years???

We should try and make a Master List of them all. Not sure I have ever seen this in one place before.

Cheers,

Dave

928er

kibort incoming.... 3.... 2...... duck~!

DR

No worries, I put up a trip wire... plus wasn't the one he ran for all those seasons "factory stock" :-)

928er

yeah but he was also an American Gladiator.....

Aspkiller

Hi Mike-

As you already know, I'm a big fan of yours.Your work is absolutely first class. But, I would like to suggest that there might be another reason for not quantifying the cost of your motor. By that, I mean the "retail" cost of your motor had you built it for someone else in an arms-length transaction. I can only guess that it might be somewhat more than most would imagine, given the quality of your work. When I try to total up the money spent on my '91, I quickly close the spread sheet, cause it hurts to think about it.

But, I fully appreciate that you built your race car and continue to improve it for the sheer enjoyment of doing so. As have I.

Regardless, Greg is absolutely right about the fact that a lot more R & D has been done on LS engines than 928 engines. Which results in the substantially lower costs of custom and after-market performance parts. However, he is assuming facts that are not in evidence, when he says things like:

I've been trying to figure out how to explain this to you....and it is really tough when all someone wants is fast....as cheap as possible."

I understand that he has a business to protect and grow, but I truly don't need it "explained" to me.

Mike Simard

DR, I'm going to be in the SCCA race at Road Atlanta Nov
5-6.
I'm in ITO which is this region's equivalent to Kibort's class.

I have slots for 'crew' members available if anyone wants a pass.

heinrich

Mike Simard

I could tally up a price list easily enough if I were to build one for a customer but I'm absolutely not going to do that for my personal car. That demeans the significance of what I've done as a labor of love.
And if I did quote someone for an engine and the price was higher than any Chevy motor on Earth, so what? Not everyone looks at their passion as something that has to be handled as cheaply and easily as possible.

One frustrating experience I had at a car show was seeing a 62 Pontiac across the lot. While walking there I imagined the possibilities of unique engines such as a 421 or 3- 2's induction. When I got there it was a LS Chevy motor and that sucked. I don't care how easy and cheap it was for the owner, it was a lost opportunity to savor rare and fascinating engineering and I feel cheated by wasting my time walking to it. Why did he even bother to display it and even prop the hood up as though I'm going to be impressed by his cheapness and laziness?
So this is where I come from if I ever get on a chevy rant, it's because of what could have been, in this age of cheap and easy. It's not the engine itself. I hope you understand.