1982 928 Weissach Edition US
1.Would raising the compression on a 4.5L motor be a good choice during rebuild and how woudl it affect reliability. If so how much of a raise?
2.What regrind or hardweld would be a good choice for more power and reliability. I'm looking for mostly low-mid range power. Also, does anyone know what cam profile the ''EUROPEAN Settings'' are? Because my 4.5l is a US version.
Thank you ,
Cory johnt

I know these are a lot of questions, so i'm asking the people I can trust.

 

Cory,

Don't waste your time with trying to modify that 4.5L engine. I'd go straight for a Euro transplant or get a 5.0L bottom from a US 85-86 and bolt your heads to the larger displacement motor but then you'd need the Euro intake to get the flow right. Really, the Euro transplant will be the most bang for the buck. An S4 transplant would also be fun if you could get all of the drive train and electronics cheap enough.

Do not use welded cams. I was in Harry Wilson's shop the day he took a welded cam from some guys 944 and the trailing side of the welded cam started to disintegrate. He said this was extremely common with welded cams. Devek also learned about welded cams disintegrating in one of their high dollar high horsepower engines and causing it to basically grenade. I'd try to find a used set of the billet Devek cams or a used set of the Euro cams.

 

What else has to be bought in order to complete the Euro motor transplant?
Cory

 

Ok well I'm going to need to find a good Euro motor that has the 300hp. Including what year, what components have to be worked in order to fit in to my car. Any help Jim?
Cory

 

Cory,

The Euro "S" motors are hard to find, and individual top-end parts (heads/cams/intake) are also very rare here in the US. (Caution, there are Non-S Euro models that don't have the higher power, check for the proper part numbers!!).

Your '82 928 has L-Jetronic injection. The Euro models never used this system. From '80 to '83 they used K-Jetronic CIS, the same as the '77 - '80 models. For '84 - 86, the Euro "S" motors used L-Jetronic (hot wire) that didn't appear in the US until the S4 in '87. So, there is no direct replacement for your '82 injector and brain with the Euro motor. It is possible to hand hone the air channel that would connect the US L-Jetronic MAF to fit the larger Euro throttle housing, but it is a custom job. You'll need the air intake tubes from '84 - '86 to accept the L-Jetronic injectors.

I'd focus on headers and improved exhaust. There is no easy way to coax much more HP from the 4.5 and 4.7 liter L-Jet motors. Transplanting a 32-valve motor would be major surgery, the wiring would have to be changed in addition to many other items.

 

</font><blockquote><font size="1" face="Verdana,Tahoma,Helvetica">quote:</font><hr /><font size="2" face="Verdana,Tahoma,Helvetica">Originally posted by Weissach1982:
<strong>1982 928 Weissach Edition US...raising the compression on a 4.5L motor...how much of a raise?
2.What regrind or hardweld would be a good choice for more power and reliability. I'm looking for mostly low-mid range power. ...Cory johnt....</strong></font><hr /></blockquote><font size="2" face="Verdana,Tahoma,Helvetica">Cory,

I always like raising the compression ratio if practical. You have a US 82 so your compression ratio is 9:1. I bet it would take 10:1 with a little combustion chamber work. This can increase torque (and gas mileage!). Ask your engine builder/machine shop about milling the heads. (Max amounts that can be milled is in the tech spec handbook.)

You say you want low to midrange grunt? For that reason alone, I'd stay away from a more radical cam grind, or euro S heads/intake. These all increase the top end with mostly no reduction in low to midrange power.

Headers probably will not give you that much in low to mid range. I'd bet a better (does that mean "no") cat and/or good cat-back would be more cost efficient in this power range.

Good luck, keep us posted.

 

How about a centrifugal blower?

If you stay NA, go for the 5.0 conversion with your heads. It has been done, but you need to be careful about the CR when you are done.

I have measured the CR of the 81 engine right at 8.1:1, not the 8.5:1 or 9:1 in most of the literature. I will be double checking, as mine needs to stay at 8.5:1 or lower. I don't think the car is anywhere close to 9:1...this was probably a marketing move on Porsche's part. You could go to 10:1 and probably be fine. I don't think the ignition is that agressive on the early cars.

 

I have the shortblock for a 4.7 Euro S for sale right now on Ebay. I am still using the top end, but for your purposes, simply adding the lower end would allow you to stay with your existing top end, and probably see a bump of significant rwhp.
<a href="http://cgi.ebay.com/ebaymotors/ws/eBayISAPI.dll?ViewItem&item=2414575162&category=33613" target="_blank">http://cgi.ebay.com/ebaymotors/ws/eBayISAPI.dll?ViewItem&item=2414575162&category=33613</a>

 

I have acess to a complete 82 Euro motor that has been upgraded to the L-jettronic injection system it will plug right into your current computer. It was taken out of an 82 euro about 4 months ago.

If you want more information email me.

 

Thanks guys!Ok so i'm looking at either doing the Euro Conversion or 5.0block with my heads/cams/etc...from what everyone has said they both seem reasonable. What are the advantages using the Euro transplant over bolting in a 5.0 block to 4.5l heads and Euro intake?
Thank you,
Cory Johnt

 

More questions...I'm learning guys! bare with me.
1. What is the Compression Ratio for 1982 4.5l motor? What would be the best raised compression ratio for my motor without having to buy new pistons due to them hitting the head itself?
2. Does anyone have copy of the Tech Spec Handbook? I'd really like to know if my pistons are domed,flat etc. Basically anything that will help me understand my motor.
Thank you,
Cory J.

 

Weissach,
The Owners manual amongst other literature states
10.0:1, 240HP in the M 28.09 & 10, 4.5L engine.
Top end 140mph at 5250 rpm in the Auto.
Top end 144mph at roughly 5250 rpm in the manual.
S models of the same year were 4.7L, M 28.11/12
engines making 300HP at 5900rpm at the same 10.0:1 compression ratio.
The 82' has a + or - 2% govenor cut out at 6200 rpm. Plugs Bosch W 8 D (W 145 T 30) 28deg. BTDC
The S' has a + or - 4% govenor cut out at 6500 rpm. Plugs Bosche W 7 D (W 175 T 30) 26 deg BTDC.
HTH

 

</font><blockquote><font size="1" face="Verdana,Tahoma,Helvetica">quote:</font><hr /><font size="2" face="Verdana,Tahoma,Helvetica">Originally posted by Dan Perez:
<strong>You have a US 82 so your compression ratio is 9:1. I bet it would take 10:1 with a little combustion chamber work</strong></font><hr /></blockquote><font size="2" face="Verdana,Tahoma,Helvetica">I like to get this info off the highly useable summary of tech spec books that 928 Specialists publish on their website. (Big thanks 928 Specialists!)

The 9:1 spec is for the '82 US model. A 10:1 ratio is given for the '82 4.5 Euro model.

Call 928 Specialists to order the spec book for your model.

 

If anyone with a 4.5 or 4.7 engine needs to rebuild it there is almost no reason to spend all the time and money to slightly overbore /hone to make a 4.6 , 4.8 . Why not do it as a 5 liter with 100 mm pistons ? The only downside of using the 100 mm 4 valve piston is having to notch new valve reliefs AND it becomes an interference motor(valve bender) . The five liter 16 valve has good compression 10-1 more torque and power by virtue of being bigger , add in some Euro parts , 85-86 32 valve exhaust manifolds , X-pipe , high flow exhaust and they can make about 300 hp at the rear wheels !. Which in a lighter weight early car gets to be really fun !!!

 

Hi Jim,
I like your ideas! If my engine ever has major problems, I would seriously consider doing something along the lines you've suggested.

Are you suggesting bolting on the 16 valve heads onto a 5-liter block -- or just boring out the existing block to 100mm? Can the early blocks be bored that much? And if so, what to do about the special cylinder coating?

With the increased compression ratio, how big a problem is predetonation going to be?

While we're at it, what's your take on the Euro cams and intakes on such a setup? My understanding from previous posts is that the Euro cams probably don't make sense with the US compression ratio, but at 10:1 they would probably be ideal here. Out of curiosity, what's your impression on the relative gain with the cams versus the intakes -- do you get most of the oomph from one or the other, would it make sense to start with cams only first while the engine's apart?

Finally, about the piston notches... um, how to determine the exact size and location? I'm just trying to figure out how to make sure the machine shop would get it right, and what info I'd need to supply.

Thanks a bunch!
Rick