fortee9er

Why go to the trouble of finding an M28.21/22 Euro engine or the top end, to build a Euro Hybrid, when the M28.43/44 make almost the same power but at a lower rpm range? Inquiring minds want to know the advantages and disadvantages of both.
Thank You

Rob Edwards

They're very different engines- M28.21 is a 4.7L 16V with 10.4:1 compression and 310 hp, while an M28.43 is a 5 liter 32V with 10:1 compression and 288 hp. While both are LH-Jetronic with a MAF, there are a lot of detail differences in the wiring, brains and CE panel that would be challenging unless you've got a lot of time.

Here's a link to a version of PET that includes the Euro S (M28.21/22) engine specs. Look through the first 60 pages of the pdf and you'll see in the far right column the number of times parts specific to 1 engine type but not the other are called out. Many differences.

https://webfiles.uci.edu/redwards/pu...86_KATALOG.pdf

ROG100

As always Rob is totally correct but check for option M251 as these cars had a lower CR and lower HP.

M28/21 & 22 engines are screamers and better than the M28/43 & 44 IMHO

hwyengr

There's only one 928 engine on display in the Deutsches Museum in Munich, and it's not the M28/21

mark kibort

why? because if you have a 2 valve car, nothing will work with the M28-43 engine. totally different.

the reason to use the bottom end, is to leave the top end and electronics the same, and just increase displacement. if you have a 2 valve car, how would you do the M28-43? new brains, wiring, fuze panel, etc etc, infinity!
with a euro hybrid using the 5 liter bottomend, its a cheap bolt on affair.

as far as specs..... the euro has a little more compression 10.5 vs 10:1. no big deal... but the main differences are in the smog catalyst equip, and the heads. the M28-41 (s4) has the same 5 liter bottomened but bigger valves and a little higher compression, but terrible cams, making 310hp near the same as the euro 4.7....
the 28-43 engine makes more power if the heads from the S4 are used. 11-12:1 compression and the intake might be better as well.

back to reality, the cams of the euro M28-21 are pretty good heads have big valves and on top of the 5 liter bottomend, it makes 290 restricted (Ljet) and 300-310rwhp with CIS or MAF, which is almost as much as the S4 makes with similar mods.

ihoe

But how do the M28.43/44 with a x-pipe and the PorKen chip compare to the M28.21/22 Euro engine? I have only driven the 32v engine.
At least on paper the M28.43/44 has peak torque at a much lower rpm which should make it more driveable in normal traffic conditions. It should also work better together with an automatic gearbox. Personally I seldom feel the need for a screamer engine in the 928. But maybe it is just because I havent driven the Euro engine.?

SMTCapeCod

No, I think you are spot on.
Screamer engines can be fun when you can give them their nose/free reign and run them out.

I would bet that the 32V has more area under the curves reagrdless of what the peaks say, but I could be wrong.

Some versions of the RoW cars come with steeper rear diffs to alleviate the feeling of the softer lower rpm responsiveness. They can also add fun as you can run through a given gear more quickly- adds some pleasant drama.

But realistically, look at the incremental HP gains being talked about for the hybrid vs chip and x pipe, doesn't make sense to me. best bang for buck seems to me to be lower priced but OK/maintained S4, intake refresh, Victor F/I.

Interesting to read about the S4 heads on S3, guessing pistons are different moreso than the heads. Don't know that I'd want to be running 11.2 nowdays, on a regular basis.

fortee9er

Maybe I should clarify my question:
If I have a complete M28.43/44 (wiring harness, ECU...etc), in good working order. Am I better off swapping the M28.43/44 into my 1983 USA car rather than (attempting) building a hybrid 5L 16v engine?
Yes I know, they are completely different engines but looking at the hp/tq numbers for both engines and the M28.43/44 is not much lower than the M28.21/22 and it makes peak torque at 2700 rpm rather than 4000 rpm.
To me that looks a plus in favor of the 32v engine swap. Any way you go Euro Hybrid, stock M28.21/22, or stock M28.43/44 you get an interference engine.
Please don't take this post as being argumentative, I just don't have the knowledge and experience you guys have. I've spent many hours reading this forum but that does not make up for hands on experience.
Thanks

Lizard928

If you already have a good 43/44 engine, harness, brains, and MAF, then dropping it in to your car will be infinitely quicker and easier. Adapting the wiring is easy.

James Bailey

Relatively easy...... if you are paying a shop like Andial figure about $10,000 for that engine swap...with all the parts brains time needed to make it run....had a customer do that !!! he already had the engine......just nothing else.

GregBBRD

Yes, swap what you have. The '85/'86 4 valve engine will work great with your "US" transmission, which has "taller" gears.

Porsche build the 1987 S4 engine because the M28.43/44 disappointed them when compared to the M28.21/22, which is why the Euro cars got that 2 valve engine in 1885 and 1986.

The US models got the 4 valve engine because it would pass US emissions and the M28.21/22 would not.

James Bailey

the 85-86 4 valve was an experiment.... Porsche learned that head studs were a bad idea.. small valves bigger cams was not all that great. The right angle intake junctions mat not have worked all that well and no knock sensors limited the tune.... So major redesign for the 87 S-4 ....

mark kibort

I like the "nothing else" needed that costs $10k

I think you are dead right about the natural progression going to the 4 valve heads, on par cams , and the 5 liter increase for more power. there is no problem with the "taller gears" actually, the taller gears are lower for most of the areas you would use the car on the track, and that I would use the car on the street. So, if he has the entire harness and computers, sure, that would be a nice project. the HP curves are almost identical for all practical purposes. slightly more hp down low due to the larger displacement. that really only accommodates the wider spaced gears of the 928... and the gears are spaced near the same , euro vs US.

yep...... they did work out all the bugs...kind of.... certainly made a better motor, but should have used the Cams from the 85-86 (which is like GT) but I guess they needed to differentiate the GT when it came out with the cams and new rev limit.

You have to weigh the cost of putting in all new wiring and how it attaches to the fuse panel, and all that might not be that easy. just using the short block is a interesting idea because you take the block, re-ring the pistons , put new bearings on it and bolt all the euro stuff that works , on the car.
I don't know..... if its easy to make the 85 stuff work, then sure, bolt that engine in the chassis.

RennPartsDirect

Can you elaborate on the negatives from your statement above? If you are considering looking at an '86 engine swap from a donor car into an earlier model year what things should you carefully look at before moving forward?

James Bailey

The 85-86 engine uses head studs like the 16 valve but the much larger heads makes removing them with the engine in the car nearly impossible. . Then the cam cover bolts screw into the heads of bolts screwed into the heads. Often when removing the cam covers those threaded heads shear off......
So a simple oil leak at a cam cover gasket becomes a must pull the engine in order to get the heads off to drill out the broken bolts......bolts no longer available . Over the years I talked to many customers who took their car in for a few hundred dollars estimate for a camcover gasket leak only to end up with a few thousand dollar bill.....once the engine is out better do .....