rgs944

SC is the best way to go but if you are gong to go with a GM engine it would have to be a LSx series. Another thing the OP not considering is fuel miliage. With a 450HP Chevy 350 you might need another fuel tank. I wonder if you could break 10MPG with a 450HP 350. You might be looking more like 6 to 8.

hacker-pschorr

That's open to debate......

1. Cheap
2. Reliable
3. Powerful

Pick two

This applies to Chevy motors as well.

I'm on a Corvette Racing team in NASA Midwest / Great Lakes. Our top ZO6 has an LS based engine that cost in the same ballpark as a Greg Brown Stroker for a 928. We go two full seasons between rebuilds.

Trial and error, we've had customers go the budget route, it never works unless you ***** foot around the track and don't care about winning.

The car in question took two 1st places at nationals this year and one 2nd place.

It all depends on what you are looking for.

A custom crank, set of custom rods, custom pistons etc.... do not cost any less for a Chevy motor than a 928. A good Chevy engine builder is going to cost the same per hour as Greg Brown (if not more). Dyno time to run in the engine isn't any cheaper for a Chevy motor than a 928 motor.

Someone will point out all the available cranks, rods, etc... in Jegs for the LS motor. That's fine if that is what you want. I would not put the equivalent of those parts in my 928, or my Corvette if I had one. Been there done with with more than a few Chevy motors over they years. Those parts are great for a dyno queen.........


A "budget" Chevy motor that will last, would be one from Katech (they make the engines for the LeMans team). They cost more than what most 928's are worth.
Add to that the cost of a conversion into a 928....... remind me how is this a cheap option versus a supercharger kit that costs less than $10k and bolts on over a weekend?

bronto

Like Brian said... It's an '84 Euro. If you want to do a conversion please go and get one no one will care about. You could sell it and be better funded for a conversion. This makes no sense.

dcrasta

Any data to support this ? FWIW I would argue the Dodge Hemi engine has more history than a SBC but thats just opinion.

What the 'purist' get that the transplant artist dont seem to get is that a powerplant is often one of the reasons the 'purist' love the cars. A ferrari or Lambo with a chevy v8 loses so much of its panache its not even funny.

If you dont know you wont know...

Hilton

The internals on the 928 motor are insanely strong for their stated power output; Porsche went to town on over-designing them. There's very little that goes wrong with the long block, and a compression/leakdown test and quick 2/6 rod bearing inspection while replacing the 20+ year old cork oil pan gasket is enough to verify condition.

These aren't motors that require a rebuild until unfeasibly high mileages - one local 928 workshop tore down a 90GT's motor with 200k miles on it (330k km's) and on measuring, found bearing clearances, ring gaps etc. to still be within factory new spec, and the same mechanic who did the measuring has been working on the car since it was new (he's an ex-factory tech, now independent), so its known not to have been rebuilt previously. The motor was pulled to do a complete re-seal of all the rubber bits, gaskets and electrical sensors, and while it was out, the owner elected to replace head gaskets to save on future labour expenses. Not to say you can't break one of these motors if you really try, but for general street driving they're nigh indestructible.

There are plenty of 928's making 500+rwhp on stock internals with stock headgaskets (heads never been off). The nutter in this other thread is currently making 650 at the rear wheels from memory.. still with the stock headgasket it left the factory with.

17prospective buyer

The ONLY reason the 928 engine is expensive to make power on is economies of scale... the amount of aftermarket parts for American V8's produced en masse is encyclopedic, end of story. Leave purists alone, and they'll leave you alone.

dprantl

This is funny considering my GT just now crossed 247k miles. The supercharger was installed when the car had ~170k miles and the car puts out about 60% more power than stock when including supercharger parasitic losses. The 21 year old headgaskets are still there from the factory and other than the supercharger sitting on top (also bigger injectors and engine programming), the rest of the engine is bone stock. I hit 8psi of boost in it almost every day.

Lumping every single cast-component NA engine in the entire world into one bucket and saying that it's a bad idea to add forced induction to any of them is not that intelligent IMO. At least before you go saying that, do some research on how strong the 32v 928 engine really is. Hmm... maybe that's one of the reasons why it's more expensive than a Chevy crate engine?

Dan
'91 928GT S/C 475hp/460lb.ft

TXBenchRacer

At least it's one still on the road and not turned into a smart car or a can...

To each his own... there will always be purists and those who will do what they want.


Gotta ask are you saying 6 to 8 out of a carbureted 350 or just any 350 including a ls..??

77tony

I don't know where your getting your mpg #'s. Had a LS3/436 hp in my 08 Corvette 6 spd auto and got 27-28 mpg highway. The plan now is to install a LS376/525 hp in a rescue 80 928 along with a T-56 6spd manual and expect to get close the the same mpg. I would of liked to have kept the stock 219 hp motor that came out of a 79 and supercharged it, but would of wound up with lets say lets say 290-300 hp? I wanted more power than that and so opted to go this route. As it stands now, the GM performance motor, starter, serpentine system that includes a new alternator, a/c compressor, p/s pump, harness and computer delivered to my door was $ 8,636 and that's with a 2 year warranty. The used Z-06 6 spd manual trans/diff/tq tube/shifter (16,000 miles) delivered was $ 2,500. Add a Stage 2 clutch, pressure plate, t-out, mid weight billet flywheel comes in at $ 700. I sold the low mileage 928 motor and plan on selling the trans/diff soon to defray costs. T

SeanR

You don't know much about the 928 engine do ya.

Aspkiller

Spoken like a true professional who owns his own machine shop and makes 928 race parts for sale.

Calling GM conversion owners lazy and cheap is a lazy and cheap shot.

upstate bob

Maybe it would be more acceptable with an aluminum block from Donovan or a Ford from Stage 3.
Personally prefer overhead cams to pushrods. I look at my old 4.5 as a museum piece and treat it accordingly. -a little off subject but WHY do folks show up at cruise nites with new Camaros and Mustangs?
If you want to see one of those you can go to a dealer showroom. yawn

FiveElements

Am I incorrect? but with affordable improvements to intake & exhaust, isn't the 928s4 or GT engine able to produce 400+ HP without forced induction and still be lighter & run for 300,000 miles? And with turbos or SC the 928 motor can produce 700+ HP like Todd T's 87 car? Seems like putting a Chevy motor in would be better with a 914 Porsche or a 944 (if it would fit) I have seen 914s with it.

Hilton

Another amusing thread for you on the weakness of the stock internals..

825 rear wheel horsepower with dyno sheet on a stock block with original head gasket

(more build info in this earlier thread: https://rennlist.com/forums/928-foru...-2-4-10-a.html)

James Bailey

YES you are !! the 928 engine is heavier , and gaining a true 30 HP is about it for simple intake and exhaust mods .....any more is ??? dyno readings !! But yes the 928 engine is built pretty strong and very durable at normal horsepower outputs. Part of why it is so big and heavy