Engine weight 928 vs 6 liter GM FI

[redrider]

I'm new to the forum but I'm planing to swap a 6 liter GM motor, Caddy Esclade, Chevy pick up truck type engine, into a 5 speed 928 using the RH kit. The 6 liter GM has a cast iron block with aluminum heads vs the LS1 thats all aluminum. The reason for using the heavier motor is I don't want to upset the 928's perfect front to rear balance. My question is does anyone know what the weight of the 928 motor & the 6 liter GM motor is? Many thanks.

[lizard928s]

I personally dont understand doing this swap, esp in a 5speed.

Imo the GM/chev engines dont rev fast at all, and in a 5 speed that is what you want (or at least I do).

[Danglerb]

Have you talked to the RH guys, or maybe a visit to http://www.porschehybrids.com/php/ ?

Do you have a kit yet?

610 lbs is the figure I recall being tossed around for the Porsche 928 motor with I think accessories, but I don't know what the Escalade motor tips the scales at. Its from a different class of vehicle so the motor ID automatically will fail smog inspection depending on your state.

Everybody that races a 928 looks at stripping out between 300 and 500 lbs anyplace where its possible to remove weight, then you put the car on a set of 4 wheel scales and adjust the suspension to compensate for the weight balance. Using a less than best option for the motor is NOT a good way to go.

*** BTW if your serious on this, this is kick off on a LONG conversation. Do you have a donor car yet? Where are you located? Spill all and lets talk.

[rich]

I'm not trying to be a smart arse. Please don't take my post the wrong way. My only question..... Why? This coming from a guy that owns several conversion cars.

It's your car, but there are too many other ways in life to turn a large fortune into a small one.

Have you reserched the resale on that mutt? Respectfully, Why don't you sell the 928 and buy a Vette?

[Danglerb]

When you've got the conversion bug, reasonable is a lost concept.

Comes back real strong a few weeks into it though.

[Normy]

I've seen a few conversions, they look well-done.

-I've also heard that in the end....it is a huge pain in the butt AND the car performs about the same AND it usually winds up costing more than simply rebuilding the original M28 engine.

From the manuals, my M28-21 engine is listed as weighing 260 kg. That works out to 570 pounds or so, and everything I've ever heard is that an all-aluminum small-block chevy weighs about the same. The iron block gm stuff weighs about 70 pounds more.

If you want a lightweight V8, try a 5.0 liter Ford. These engines are actually lighter than their 4.0 liter V6's.

Good luck-

N

[Mule]

A late model small block Chev can produce 500 hp without a whole lot of trouble N/A. That would make for a stout 928.

http://www.gmperformanceparts.com/Parts/showcase_detail.jsp?engine=3

[Herr-Kuhn]

So tell us how much it costs to do a full installation of a 500+HP Chevy conversion. I lay money that I can bolt on turbos in about 1/5 the time and do the whole job for less money and headaches than a push-rod V8 conversion. What does a fully running 500+ HP Chevy engine cost these days...must be at least $8K if you include the engine, injection, harnesses, clutch, conversion parts, mounts, etc.. It may make sense if you have a blown or ratted out 16V, but to replace a good 32V S4 engine with a pushrod V8 on the basis of better performance holds no validity. I'm not knocking the Chevy power, but people always make these claims on costs per HP that just are not valid anymore. There are too many options available today to increase the 32V S4 engines to super-car status and all of them cost less than installing an equally powerful pushrod V8 conversion. Less headaches, more power and less money and most times the 928 engine never even leaves the chassis.

The last 928 engine I bought was a M28.12 full 4.7 Euro engine and I paid $325.00 for it, complete. It was pulled in perfect running order when pulled, and was slated to be replaced with a lower power Chevy caurberated conversion setup because the owner had been told so many horror stories of 928 repair bills. A 75,000 mile engine in perfect running order pulled and replaced with a lower power Chevy conversion...it didn't make sense to me but I wasn't about to complain becasue I stole the Euro engine. I've seen the Renegade site and a lot of what they say is BS overstatements of how bad the 928 engine is, it doesn't last, etc. A $ for $ comparision of a S4 based Chevy conversion compared to a boosted S4 based car and there is no doubt which will cost less and run better and hold value longer. With 180,000 miles on the clock my S4 based build is making a reliable 600+ HP off the flywheel and I doubt you could buy the Chevy engine and installation bits to do the swap and make the same power for less money.

16V is a different story, but with the right parts even a US based 4.5 liter can be built out to 300 HP for not too much money or effort. Or, one always has the option to install a newer 928 engine into an older chassis. I have a lot of respect for the guy on here that put a 16V 928 engine into a 914 instead of going push-rod conversion. It is a much more elegant solution in my book.

[Danglerb]

LS1 pulled in good running condition with all the harnesses and brains is not hard to find for $2500. Add another $2500 to spruce it up, maybe $4k in conversion related parts, total cost maybe $12k doing most of the grunt work yourself and only paying for tech stuff. Motor should be very reliable, no issues turning left at 6k+ rpm, around 450 rwtq and rwhp, and it should be able to pass a Calif smog inspection.

If the 32v motor is running good its worth $3k, even if its not it still should sell for maybe $2k.

Converting an early car like a 78/79 might go a lot easier on the electrical stuff.

Do I think its a good idea?

Not to my taste, but maybe not for the reasons you would think. My view is a big fat torque curve isn't that good for a street car, and that a lower powered peakier 16v 928 motor is going to be more FUN to drive on the street. If I wanted a dragster I'd start with a Mustang.

*** Side benefit of the Chevy is that you not only get the motor, you get a modern accessory loop with cheaply replaceable high output parts and NEW fresh wiring, reliable brains, etc.

*** Despite the poor resale on some early "project" conversions, completed nice cars are at least in the $20k area.

[Normy]

Originally Posted by arclight53

The LS1 with aluminum heads weighs about 97 lbs less than the 32v 928 motor, and about 55 lbs less than the 16v 928 motor. Reynolds 390 aluminum is a very dense, heavy aluminum, not like screen door or beer can aluminum. The wide block, fat heads and extra cams on the 928 weigh a lot. The conversion is straight-forward, not too painful of a job if you have genuine mechanical skills, as opposed to "keyboard" skills which are apparent on many of these lists. In other words, if you just talk the talk, you're not going anywhere with this real fast, gotta be alble to walk the walk. Renegade's kits are very good nowdays, were pretty poor in the beginning.

As far as power, even a stock LT1 conversion will outpower the stock 16v 928 motor, bigtime, while getting better gas mileage. A stock LT1 conversion will very marginally (barely) outpower an S4, but it can be upgraded for less money than it would take to upgrade the S4 motor to comparable power levels. While single cam 2v pushrod/rocker arm motors seem inferior to 4v dual overhead cam motors, they can be built to produce more power on a per cubic inch basis, and for less money.

Well, that's interesting information. I was told that the aluminum sb chevy motors were about the same as a 928's M28.

You don't know much about M28 engines. A 2-valve US model M28 makes 234 hp from 4.7 liters, but if you add headers, a good exhaust, such as the Borla that 928 Inernational sold [I don't know if they are still available], and an X-pipe, you can gain about 30 horsepower. My 928S2 has a two-valve M28-21 [commonly called a "Euro", this car was sold in Austria and brought over. They are available on eBay and occasionally on Rennlist] and it is rated by the factory at 310 hp. I have the Borla and the X, so it probably makes something like 330 out of the box. Back when I had tires that could actually HOOK UP...I got into a "stoplight derby" with an S4 and put two car lengths on him quickly. He was trying because at the next light he asked what I had done to my car to make it faster than it should be.

I'm sure you can make an sb chevy very strong for minimal dollars, but the man that owned the car that I pictured above? He told me that he had to find a bellhousing off of some odd early-'60's gm product that RH didn't supply. And he had to take a walk through hell to make the chevy upper radiator hose work with the original Porsche radiator...which requires a metric hose. Those are the sorts of headaches you face if you try this. I suspect that RH is a group with a lot of knowledge, but their kit leaves something to be desired.

[The car above was owned by Rob Budd up in Michigan. He's on Rennlist]

-Don't get me wrong; if my timing belt skips a tooth tomorrow and I have to rebuild the engine myself, I will probably need 6 months to do it and I'd consider buying a Renegade Hybrids kit and an old chevy van engine out of the local paper just so that I have a car to drive while I rebuild the M28. After the M28 is finished, I can always put the RH kit on eBay. Of course, I'm a bit of a 928 purist.

B safe!

N!

[rich]

I could have easily gone the Chevy route. Infact I drove my car up to RH front door and had a nice chat with Scott about the subject. As you can expect, his only question to me was "why the 928?"... When they are tossing them out like used condoms. Infact he showed me a 928 that they had just completed. My friend purchased the engine they removed.
It comes down to this for me. If I wanted to build a chevy I'd buy one. It's a respect thing for me. I guess you could bring tater salid to dinner with the queen but I'm not sure it would be any better received than two week old carp. No matter how many chrome fastners you use it's still a generic chevy. I can get one of them out of any old field car. None of this is meant to dis someones project. I've built and drag raced BB chevy's and I still have a few performance parts here and there for future builds. Just my way of approching the validity of a conversion.

[lizard928s]

Now all you need on that 914/8 is a pair of turbos

[Danglerb]

I think Rich might settle in the short term to getting it running again.

[Mule]

John, don't beat on the pushrods too bad. One day I was at the races, talking to a guy who builds $50k+, 2000 hp small block Fords that run all season on oil changes. I asked him why 2 valve motors dominate drag racing when 4 valve motors have so many advantages. His head snapped around. According to who, he says. Uh, everybody, I reply. He says, it depends on what you're doing. He says, "No faster than we spin these motors (9K) pushrods & 2 valves work fine. In fact, they make more torque." I didn't argue with the guy. He's not some hot rod clown. He's an intellectual type who comes off more like a college professor & he rarely goes to the races. He just builds engines that win.


I've never been in a Euro that felt like 300 hp. I've drilled a couple with my S4 that's stone stock with a chip & a K&N. One I beat had headers, a chip & those magic silverstone plugs & wire. I put a length or 2 in each of the lower gears. If we'd had the room, I'd have left him like he was tied to a tree. To get a n/a 928 motor to run with a good ls motor would be expensive.

[Danglerb]

S4 main advantage over the 16v Euro S motor is 50 ftlbs of mid range torque, but thats a big leg up on the street.

Greg is building a Euro hybrid right now, basic clean up and port matching on intake and heads, I'm not sure if it will have headers or not, but I think it will get Sharktuned. Should be done about the same time as my stock Euro S motor gets into my 85 Euro, which I think will also get a Sharktune. I am very much looking forward to a comparison.

[Herr-Kuhn]

The 4-cam motor is pretty refined. No doubt a big head high lift cam 2-valve can make big power. I'm just not a fan of mix and match builds. I think the M28 engines are a nice piece, but so often they are misunderstood and dismissed as not worth doing anything with. I think a lot of that has changed in the last 3 years with the options now available.

I have to disagree with people saying how terrible timing belt changes are...you only do it like once every 3-5 years and it is not at all a difficult job.

That 914/8 with a pair of turbos would be wicked for sure.

Mule...keep in mind with a 4-valve head the plug is typically centrally located which makes for a cleaner burn and a setup that is less likely to detonate than an older wedge head. A 2-valve 928 can make good power for sure, especially the Euro motors...they make quite a bit of torque.

I'm just not a fan of the RH marketing campaign. I'm sure they make a good product but the 928 motor is not the unreliable and low power piece they paint it to be...not even close. It suits thier agenda so they tell the story. They compare new 5.7 liters to the older 4.5 928 engine. That is not a fair comp at all because the 4.5 can be built up and additionally the fair comp is to take an early 80s vintage GM engine and then do the comps...you'll see the 928 was not as low on power as people claim. It's really not that hard to squeeze 300 HP off of an older 4.5 liter with the right parts.

[rich]

Believe me, If there was room...LOL

[Danglerb]

I could have this wrong, but don't the 16v US, plain Euro, and Euro S motors all make the same low end torque, say at 3000 rpm?

I think the 928 may be the best GT car ever made, but some parts are a lot more excellent than others. The least excellent bits are the motor, transmission, accessories, and the material the dash and pod are made out of.

If you don't do your own work, and aren't lucky enough to have one of the very few good 928 mechanics local, your screwed with the 928. Drop in the chevy and maybe, just maybe, the local Chevy guy can work with it.

[Normy]

Originally Posted by Danglerb

I could have this wrong, but don't the 16v US, plain Euro, and Euro S motors all make the same low end torque, say at 3000 rpm?

I think the 928 may be the best GT car ever made, but some parts are a lot more excellent than others. The least excellent bits are the motor, transmission, accessories, and the material the dash and pod are made out of.

If you don't do your own work, and aren't lucky enough to have one of the very few good 928 mechanics local, your screwed with the 928. Drop in the chevy and maybe, just maybe, the local Chevy guy can work with it.

You are right on how the 2-valve 4.7's run below 3000 [actually, it is more like 3500] rpm. Below 3500, the US 4.7's seem pretty strong, but not outstanding. When they go above 3500, they are similar to American engines.

My car: In first gear rolling at 10 mph: I floor it [when it is running right], and the car picks up quick. It goes about 200 feet, and then the rear tires start breaking loose and it "axle-hops", I can feel one of the tire-axle combinations bouncing. bbBBWWWAAAAAAAA! The engine is starting to use its' very long duration camshafts and starting to get into the power band, and it is developing more torque than the tires can tame. The back end goes about 2 feet sideways, scaring the ***** out of me. Second gear sends the rear end out a second time. If I shift just right, it won't continue spinning in third gear- it just straightens out, hooks up and your neck goes backward and the car goes forward. This thing is hard to launch!

If I slip the clutch off the launch, it goes sideways instantly. This thing wants to go sideways at 30 mph just from power alone with no change of clutch! What's more, after I bought it and took it out on the highway, I downshifted to 4th gear and floored the throttle at 90 mph. The back end lost traction, and started to go sideways....

That was after I bought it, when it had junk hard rubber tires.

My tires are Falken RT615's- which I highly recommend. They have about 5000 miles on them now and they are toast. They are vulcanized [hardenened], which explains my traction problems as of late since these are the BEST tires I've ever put on a car. Though I only got about 5000 miles on them [that is two years for me], I'm definitely going to buy another set. When these things were new? This car hooked up totally, it was geared to the road.

N

[Danglerb]

I'm giving serious thought to doing what Jim Bailey does, Kumho Victors all the time.