Another Small Block Conversion Argument

[Herr-Kuhn]

Callaway Camaero anyone? I guess it's fortunate that Reeves and I likely had our last conversation 3 years ago when he insisted on telling me how bad the 928really was compared to his beloved Corvettes.

[fb111]

Rich you continue to reach. The 928 is a 5 liter engine not a 7 liter. The engine is grossly oversized for its capacity. Again a design flaw. Oversized and overweight for its intended size. Originally designed as a 5 liter engine and downsized slightly to 4.5 liters when the 70's gas crunch hit. It was never intended to be a 7 liter engine. So your logic is to saddle the chevy with the burden of the porsches untapped dimensions. Briillant.

[Jon B.]

Originally Posted by rich

ah,yah.. what else was manufactured with a chevy engine and called a Camero?

Looks like my sarcasm was lost on that one. It was a jab at your misspelling.

[rich]

Originally Posted by Jon B.

Looks like my sarcasm was lost on that one. It was a jab at your misspelling.

Oh....miss that like the speen er splinen, er ah spillin.

[rich]

Originally Posted by fb111

Rich you continue to reach. The 928 is a 5 liter engine not a 7 liter. The engine is grossly oversized for its capacity. Again a design flaw. Oversized and overweight for its intended size. Originally designed as a 5 liter engine and downsized slightly to 4.5 liters when the 70's gas crunch hit. It was never intended to be a 7 liter engine. So your logic is to saddle the chevy with the burden of the porsches untapped dimensions. Briillant.

Well again, spend the money a conversion would cost on a 928 engine and that issue could be resolved and you would still have a Porsche worth something. Spend your money any way you like. But if your trying to make cheap hp there are easier ways to have a chevy camaro without starting with a Porsche. That's all I'm sayin. You get what you pay for if your lucky. Doesn't mean it will be worth what you pay when your done.

[Herr-Kuhn]

You have to remember the 928's engine was designed to have a large cooling capacity, since the car was intended to run at high speeds for extended periods of time. Myself, I don't consider the size or weight of the engine to be a flaw...that alone is responsible for the longevity of these engines.

[stick1975]

I hope not all of us that want to do a conversion are that bad... If I had a 4 valve motor, a well sorted twin turbo kit would be the way to go, inter-cooled turbos for that matter are the best way to go for the best power to driveablity answer, IMO. Not being a purest to any make, just a follower of good design, I think a pump gas SBC, built with production heads and block, with over 1hp per. CID would be on the ragged edge of a DD, and if it does have a carb, don't expect it to stay running at the end of a high G brake stop. The same things that make it appealing to put the SBC in are also the same things that look like drawbacks to me. I don't think you can really do an apples to apples comparison, there's just to many variables, IE keep the P car ass., or convert the lines for the AC and PS for common GM items?

[icemang17]

bottom line is this.....if you want lots of reliable HP....it costs MONEY....and lots of it....

The obvious upside to the chevy LS engines is weight and cost per HP.....its about 1/2 the cost per HP as a 928 engine....

Weight is not as important for a street car.....but on a race car its huge...& the 200lbs less an aluminum block LS weighs is huge....

It all comes down to your budget and your goals for YOUR 928....

[not_hans_stuck]

Been mullin' over this conversation. I'm considering a 928 LS3 Conversion. I hadn't seen the twin turbo kit before so it's only just entered consideration.

For me, I guess it depends on the condition and year of the 928 I find. If it's a late model Euro version in decent shape, I may run it until it becomes unreliable.

For me, the power and packaging of the LS series motors is just incredible. Nothing beats it.

By the way, I saw there were some Pantera conversations going on. Pantera's were built from 1970 to 1995. Ford imported them as Corvette Killers from 1970 to 1975 so the majority that you see are from these years.

There was a resurgence in the late 80's and early 90's and a new importer brought in GT5's. So, you see these for sale too.

I personally have never seen a Pantera built between 75 and 85 but I guess they're supposed to exist.

My shop, back when I had it, restored a few of them.

AS far as the one guy who says he's 6'3" and fits in it, his floorboards must be lowered because I'm 6', 185 lbs, and I don't. My head scrubs. That's with stock seats, and with lowered and trimmed Fiero seats - the thinnest we could build them.

H

[JK McDonald]

It is obvious that without an accurate side by side analysis of all of the needed parts, fabrication time, labor and cost, there is no possible way to justify any advantage to installing a Chevy engine into a 928. From my experience over the years, I’ve seen lots of “it sounded like a good idea at the time” projects fail to produce the desired results. This type of learning experience is most effective when you are waist deep in the venture before the cold hard economic facts sink in.

Just a couple of comments - Everyone here understands that the German design philosophy behind their cars is totally different from the U.S. In many examples (drive train layout), Porsche was many years ahead of even the GM top of the line Corvette.

If you want something other than the power, refinement and long legged comfort of a 928, start your project off with another test bed. Personally, I don’t think Porsche should be mongrelized.

In the real world, hybrids are very seldom (if ever) a value/dollar effort. If you plan on charging everything off to a “just for the fun-of-it” experience, don’t even keep track of your time and expense.

If you are wanting to bump up or re-power an older 928, there are lots of comparatively inexpensive and powerful 32 valve engines/trans available that are out of the box tough, reliable and basically bolt-in ready to install.



Good Luck, Michael

[fb111]

"If you are wanting to bump up or re-power an older 928, there are lots of comparatively inexpensive and powerful 32 valve engines/trans available that are out of the box tough, reliable and basically bolt-in ready to install."

Putting an S4 engine into an early cis car is probably more difficult than a Chevy conversion.

[JK McDonald]

Hey Fred, Naturally everyone realizes there will always be an ongoing debate concerning the pro’s and con’s for installing a Chevy V8 into a 928. But surely you do not consider that the installation of a 32 valve engine would generate more issues than a small block Chevy ?

I do not consider myself a transplant expert but considering that the 928 driveline layout was designed with the proper major component location, hood clearance, exhaust, clutch/bell housing setup, instrumentation, cooling system, etc… in mind, I do not understand your assessment of the difficulty. A couple of years ago I had helped install a 32 valve engine into an 81 and later an 83 928 without too much drama other than the expected additional hardware, cables, fuel and ignition computers/associated wiring, etc... and having to make adjustments for the different engine issues.

What had prompted the final 32 valve engine selection was only after considering several other engine options along with a $10K estimate for an all inclusive LS1 plug and play parts package. If I remember correctly, the complete 67K mile S4 engine (including all the pumps, hoses, computers, etc)... was about $4,150 with the total project drive away cost of approximately $5,300.

I am not knocking the LS1 engine as a power plant in any way. I just personally prefer to leave with the same lady I came with.

Michael

[stick1975]

$5300 to change a 2 valve motor to 4 valve motor, with the computer and wiring harness? That sounds like a good return $ per HP. I think it would real hard to do the SBC or an LS conversion for that kind of money. I know most people buy the 928 bc they like the car, and you if you really like them, you should buy the nicest example you can afford, and if it is that nice, it should stay all Porsche. I don't think most people, and I know there are exceptions, but most are not going to end up selling them for a profit. To keep up a nice example shouldn't cost near as much as a conversion IMO, and if it's not fast enough, sell it and find something else. I want to do the conversion myself with an 82 US auto that is real rough. It is just bc I'm failure with SBC and LS engines. I agree with the "double your cost estimate and triple your time estimate" statement.

[fb111]

I once put a ljet engine in a cis car. Had to change the entire fuel system as well as all the electronics, wire harnesses and fuse panel. To properly remove and reinstall the fuel lines the gearbox needs to be removed. I'm sure there are more suprises when going from a 16 valver to a 32 valver.

[JhwShark]

Originally Posted by fb111

I once put a ljet engine in a cis car. Had to change the entire fuel system as well as all the electronics, wire harnesses and fuse panel. To properly remove and reinstall the fuel lines the gearbox needs to be removed. I'm sure there are more suprises when going from a 16 valver to a 32 valver.

A real l-jet like in a BMW 3.0CSi upgrade or the LH?? I've got the d-jet (original FI) in my coupe and it screams...so does the l-jet on my friends

[JK McDonald]

Here are a couple of comments in answer to an email I received. These projects were wrapped up quite a while back so I had to scrounge around in my old notes for a review of the 32 valve engine upgrade to the earlier 928‘s. If I remember correctly, the most difficult part of the whole process was to keep your momentum going while making trips back and forth to the wrecking yard for the misc stuff. Luckily, we had a complete car dedicated for scavenging. I show a diagram where a couple of fused 12volt power source circuits were added along with the power relays - but we didn’t need to change out the fuse panel. The replacement engine assembly and computers with their attached harnesses pretty well came with 90% of the wiring for the LH fuel and ignition control systems. One notation I found mentioned the fuel pump and the mounting process of the fuel lines. For our installation, the transmission did not need to be lowered. The fuel vapor/evaporation lines were also replaced because of their age. An assortment of nuts, bolts, clamps, small braces, etc.... were simply transferred from the donor vehicle. While we were at it, the driveline consumables were renewed and the instrument cluster, heating and A/C systems, etc... were gone through. Much later the brakes, wheels and tires were upgraded to round out the effort.

It is clear that everyone should thoroughly review all the available re-power options before diving in to what can be a very expensive judgment issue. Several 928 project threads have verified that it is not uncommon to invest $10,000 to have a fine $5,000 car.

Michael

[not_hans_stuck]

So, I guess there are really three options. There's the twin turbo route, the supercharger route and the LSx swap.

I wonder how hard it would be to swap a Cayenne turbo motor into it.

Wasn't last years Daytona winner a non-factory effort where they put a Cayenne motor into a Fabcar?

Hmmm.


H

[rich]

The Cayenne engine is totally delicious.

[Normy]

Originally Posted by rich

The Cayenne engine is totally delicious.

Yeah...but it will totally NOT FIT! It is too tall.

-Some people have posited that if the oil pan was left off, then a "dry sump" system on this engine MIGHT work.

I say try it- It's only cash; It will work or it won't, end of story.

AS to the chevy transplants: I personally witnessed one in Detroit. I ran like a 928. It sounded like a 928. It was driveable, it was fixeable...it was a 928. At the same time, it's value was probably half what the car would be worth with the original engine overhauled. There's the real problem with the chevy conversion- you loose a tremendous amount of resale value. It doesn't matter if you are replacing the original '78 219 hp motor with a 450 hp chevy- you are still replacing the original motor and collectors, the people who would potentially be paying for this car during an internet swap...would be far more interested if the original M28 engine was in the car. They don't care how fast it is-they just want to move the car, and originality is VERY important.

What's more- a "proper" chevrolet transplant, according to the people at Renegade Hybrids...will set you back about $8000. And their kit is incomplete- you need to [somehow] find a bellhousing part from a 1962 chevy in a junkyard. They don't have the part, and you need to find it. Hello?

-For $8000, you can easily do a good overhaul of an existing M28 engine. In fact, you can have low compression 951 pistons installed, along with 951 heads. With a few mods, the 951 heads fit just fine, and they are FAR stronger in the valve department!

I'd do a chevy transplant with some old 350 four barrel for a few months while I rebuilt my M28 in my garage...if my timing belt snapped tomorrow. Of course...there are always those Lamborghini Gallardo's on eBay....

N!

[not_hans_stuck]

I remember reading an article about the Daytona car and I think adding the dry sump to the Cayenne motor represented the bulk of the cost to using it in the Fabcar.

And from the way the article sounded, the expense was considerable. Too bad. Maybe it would fit in a 944. Don't they have more room under the hood?

As to the loss of resale value, I suppose it matters what you start with. I think doing the swap to a perfect 928 GTS would be heresy. But an early 928 hangar queen doesn't exactly command much in the way of resale in the first place.

For my own part, I think I'll see what I can find. I have to sell my 911 first anyway.