928 Euro S cam in a 4.5 - Valve Springs?
 

Hi All,

I have Euro S cams from an 84 928 16V that I would like to put in my rebuilt 79 4.5 liter. If and when I swap cams, I am wondering if the valve springs in my 4.5 liter heads are strong enough to keep the valves from floating. My 4.5 heads is already assembled and bolted on the motor on the engine stand. If anyone else has done this cam swap on a 4.5, what are you using for valve springs? I know that 928 performance has some new valve springs available, but they are honestly out of my price range right now. Any other spring options available? Thanks in advance.

The valve springs in the OB 4.5 are different from the valve springs used in the L-jet 928s, CIS Euro S, and Euro S2. I think the same springs were used for MY80-84 US and all Euro S models. I would wait on installing the Euro S cams until your budget permits the upgrade to 944 springs.

Thanks, I had a feeling that the springs were different. I think I will wait a while. I would assume that adding the 4.7 Euro S cams will also turn the 4.5 into an interference motor, due to the increased lift/duration. Ah well, just don't break a timing belt...

No.

And putting in a set of Euro Cams into an otherwise stock '79 US engine is going to not be the best combination of engine pieces. You will end up with an engine that has less low end torque because of the more aggressive cams, but also won't run well on the top end because of the low compression, unless you do a bunch of other work. You are better off using the original cams.

The good news is that those cams are desirable for people building bigger engines and are worth "big" money. Sell them and use that money somewhere that will improve your car.

You could upgrade to the 80+ springs but it will cost about $1000. I would do as Greg says and pass them on then use the money elsewhere.

I highly recommend a set of Bilstein shocks and a set of S4 springs. It will transform the car and its capabilities.

Thanks guys. Good stuff to know. Now that you mention it, I would imagine that the added duration from the 4.7 Euro S cam (versus the stock 4.5 cam) would surely lower the dynamic compression, when installed in the 4.5 motor with it's already low 8.5:1 static compression. BUMMER!! I do have a set of Euro S heads and intake that I could bolt on the 4.5, which would probably bump the compression up to 9:1 (probably still too low). However, then there is the concern whether the valve reliefs in the 4.5 are large enough to clear the larger 4.7 Euro S valves. Also, the Euro heads have those big round intake ports which are great on a 4.7 or 5.0 liter, but are probably too big on the basically stock 4.5, thus making the low end soggy. If bolting a supercharger on it, perhaps it would help. Normally aspirated, it would probably make the 4.5 run worse. Anyhow, thanks.

You need to either push the chips all in on a 4.7 bottom end or S3 bottom with flycut pistons, or fold. Even with higher CR US MY80-82 pistons, the 4.5 just isn't worth the Euro S resources.

Do you have the parts needed to make your 4.5 a Euro spec? Sounds like you also have Euro heads from a 4.5 - you have the cams and caam towers for that too. That's one good way to go to end up at 330 HP instead of 220.

A other is to use the 4.7 motor with either the 4.5 or 4.7 cams. The 4.7 with higher compression paired with even regular 4.5 cams that have higher lift and duration is a good combo. It's actually what I'm running in my K-Jet car with a 928MS Powerdyne supercharger. The combination moves the power and up a little in the Rev range, but it is very fast in the higher RPMs now or it's so much more powerful at the top that it feels like the powerband has been shifted up, when the low end might actually be the same as it was with the original 4.5.

I have a 79 US car, The original 4.5 is gone. However, the 4.5 I currently have for it is a 1979 euro spec 4.5, I ditched most of the original US spec motor except for the heads, intake, fuel distribute and some minor stuff that currently live in my shed.. The original 4.5 in my 79 US car sat so long in the previous owners garage that the old, original head gaskets completely disintegrated. blew the head gaskets so I just looked for another motor.

Regarding US 4.5 versus euro spec, the part numbers are different, but I thought the two engines were basically the same (minimal hp difference)? Are the heads the same on these two motors? (same heart shaped combustion chamber?) . Was always curious but did not want to tear the torqued heads off my new motor to find out.

https://cimg6.ibsrv.net/gimg/rennlis...ff57b9e4b1.jpg
Heads from my old 1979 Porsche 928 4.5 liter motor. Note: I have always thought that this heart shape combustion chamber was a good one.

Anyhow, hears my story: I bought a completely rebuilt 4.5 euro motor from a guy in California (on rennlist) a while back and had the motor shipped to Florida where I live. He had this motor built it for his car, then suffered a divorce and had to sell the car and new motor. This guy replaced a lot of parts on the 4.5 ( even new valves in the heads) and painstakingly rebuilt it. Also gave me boxes of new parts and gaskets for it. It's been sitting on my engine stand. I can't install the motor until I get my tired old ass back in the garage and reinstall the front suspension.

For years, I've had an itch for a 4.7 euro for my 79. Sure enough, after a long, fruitless hunt for one on craigslist, I immediately found a euro 4.7 soon after the 4.5 euro arrived, I found a euro 4.7 motor in a parted out 80 928 Euro S 5 speed parts car and dragged the car and motor home. HAD TO HAVE IT. After a teardown, I found that the low end had suffered a ton of water damage (rusty, seized rods if you can believe it) and was in rough shape and I ended up eventually selling it off in parts. In the end, I felt like I got cheated on the deal by the guy who said the motor was excellent. I sold off the good motor parts.

A year and a half ago I looked on craigslist for the heck of it and found a black 84 Euro S automatic car with no title in Orlando, Florida. Body not bad but interior trashed. Of course I HAD to have it. Dragged it home ( the wife was just thrilled). Car ran when I for it. Pulled the motor the other day and tore into it. Whole motor looks pretty good.

The idea haunted me again of using the cams or possibly complete top end on the 79 euro spec 4.5. I hate to have to ditch the 4.5 at this point after shipping it across the US. Not sure what to do. I might be best to leave the 4.5 alone as it is.

Anyway, I guess I will leave the 4.5 euro as it is....

What?? A 4.5L "Euro S" with much lower compression will make more power than either the M28.11/12 or M28.21/22?

It sounds like you have the engine you've always dreamed of, in your possesion, and it is in "pretty good condition".

Why not assemble that engine and use it?

I appreciate all of the input from you guys. What I may do for now is to just drop the 4.5 euro in my 79 as it is and run it as is. I should be able to get 300hp out of it with some basic mods. Rat hole the 4.7 euro motor and spare 84 body for later. I would build the 4.7 now, but do do it right, these motors take some money, as you all know. I would want to split the block and completely go through it, since I have no idea of the mileage on it Don't know about you guys but I have TOO many projects in life... Days flash by in the blink of an eye.

Inspect the rod bearings first. They will show wear long before the main bearings do and are a good indicator of how well the engine was maintained.

Most of the time they are still within spec and don't even need replacement. If those don't need to be replaced, your mains definitely don't.

Just take off the oil pan and pop a rod cap off, then measure it with a micrometer or plastigauge. Remember to use new rod nuts though! They're 1 time use.

What are the accepted values for these ROW CIS engines and desirable parts like cylinder heads, camshafts, induction, etc?
I have a few 28-11/12's around and wouldn't mind converting them into other needed 928 parts as recommended here.

I sold a nice pair of M28/11 heads on Ebay a few months back for $800 with free shipping. They were fresh off the motor with no machine work done. 928 Performance had a complete M28/11 motor for sale in 2017 for $3200, plus crate fee plus shipping, if you don't pick it up.These motors are getting hard to find, I saw another post there they had a 310hp twin dizzy motor for $3800. They probably got what they were asking....