Jim bailey - 928 International

You cannot use S-4 pistons unless you want 7.5 to 1 or so compression ratio. The last engine I knew of built that way would barely run and to "fix" it they tried to supercharge it.

Vilhuer

There's only 5 million of us Finns and maybe 120 928's in the country so pretty much everyone who's into 928's at least knows someone who knows someone else...

As Jim says with slightly different words, S3 and S4+ engine compression chamber design is totally different and mixing pistons and heads create either too low or too high compression ratio. While too high can be made fairly easily into tolerable level too low is very hard to work around without drastic methods. You are better off staying with 100mm pistons which have close to same piston top volume as stock 4.7L S pistons have. See this thread for measurements, many of them were done in Teemu's garage:
https://rennlist.com/forums/928-forum/344250-head-and-piston-top-cc-numbers.html

Those 600 hp large valve heads would easily give you 350+ with 5L bottom end without being too radical for street use I think. At least when used with stock ROW S cams.

928@AMG

Hi Jim and Erkka & all,

thx for your help
I didn't think of the different combustion chambers of the S4 cylinder heads . Ok I have to use the '85 S3 pistons for my project.

I really like to be my own engine development ingenieur.... to create an own engine is much more difficult as in my first thoughts but very fascinating !
If I had known about this I should'nt have moved in a normal flat , better would have been a dyno room with fully equipped engine and car workplaces + small kitchen and bedroom somewhere besides .... :-)))
Ok some more $$ won't be bad ...

Erkka , where can I get some info about the high flow heads you talked about?
I can do all head work in the facilities of my company , in the holy halls of AMG
I have one head completely new with stock valves, the other one is used .
I also have a set of stock 1981 ROW S cams . Has someone experiences with slightly sharper cams together with CIS ?
As mentioned the engine must still deliver enough driveable torque below 2000 rpm and should have good idle speed at ~ 800/850 rpm


Regards,
Thommy

Vilhuer

Send your email address in PM for example and I'll send you dyno chart and some pics of those heads. 352 hp @ 6336 rpm and 438 Nm @ 5115 rpm but I'm not sure which intake and injection setup this was. Bottom end of engine was basically stock 4.7L with larger valve cuts in piston tops AFAIK. They were used only 5 hours before 2/6 rod bearing failure.

928@AMG

Hi Erkka ,

your help is very much appreciated

BTW in my home forum www.pff-online.de i know a guy who has solved the 2/6 rod bearing failure . He does some machining job on the crankcase , don't know exactly ( seems to be his secret ) , but for affordable ~300 EUR . Of course I hand him over the case before putting all together .
Nothing is more disgusting than spending lots of money and time and then ...exitus :-(


Thommy

largecar379

you must use 85/86 pistons.....

I have a set, with 16V valve reliefs cut in them, cleaned, ready to go. With rods, or without....also have a new drilled crank (if you are going to race, you need this crank to prevent 2/6 rod journal failure).

pricing available on request--send me a PM.

--Russ

928@AMG

Hi Russ,

thanks for your offer !
I have a complete S4 engine available, but I have to part it out first. Actually I don't know the tolerance group of the cylinders of this case. As you may know, matching tolerance group of cylinders/pistons is very important.
Before I don't know the tolerance group, I don't buy pistons which eventually don't match with the crankcase.

End of June I should know more about the S4 crankcase.
A crank I think is way much to expensive to ship to germany ...also I have one in the S4 engine . A drilling job can be done easily & cheap in Germany too .

Regards,
Thommy

slate blue

Errka can you send me some pics of those heads? My address is greg.gray at optusnet.com.au The reason I ask and I did post info on this earlier my heads going on the 327 ci or 5.35 litre can flow .500" or 12.7 mm lift is 550 hp. My solid lifters cams have a higher lift at 0.550" or 14 mm these will flow about 580 to 585hp although that doesn't mean it will make that power everything else needs to be right too.

Wait till I get my results with the next engine, the 5.0 litre has done 311 hp or 232 kw at the wheels on a Dyno Dynamics dyno, add ten to fifteen percent when comparing with dyno jet. So we are expecting 350 rwhp from the 5.35 L. Will need to rev to 6700 at least.

The big engine and I am just doing the numbers, I may sell the euro heads ported with what ever sized valves the customer wants, I would recommmend 49 mm when running with a 100 mm bore, so if you want to contact me 928@AMG let me know, I don't know of too many people who know more about the 2 V heads. Runs on the board with approx more than 400 crank hp. from the 5.0 L. I can also give advise that I would not normally give to people if you buy parts from me. At this stage I haven't made up my mind what to do. The valve seats and valves for the big stroker are very expensive around $150 per seat and valve. These are needed for 8000 rpm.


I also have a solid lifter cam set with solid lifter cam box setup ready to go along with special intake manifold flanges machined and ready to go. I can probably sell you a set of those regardless as I have a spare set. You would only need these if you are going to make your own manifold and want to run more advanced injector setup, e.g the 4 spray hole type.

Greg

928@AMG

Hi Greg,

many thanks for your offer !
Pls give me some time to verify all the information I've received here in the last days .

Main objective for my new engine is 350 maybe 380hp , but still with normal driveability in german towns at low revs. As I have read, its possible to get 400+ hp , but that seems to be designated for racing purposes mostly. Reliablility and durability is also a very important issue for me.

The engine should still be able to meet the german emission laws. Car is registered for so called Euronorm 2 , which means with controlled catalytic converter. Saves at least 1000$/yr tax against same car without converter . Emission control is every 2 yrs. If the car doesn't meet the Euro2 restrictions , it's over with cheap taxes :-(

Another issue is the price . I have one complete new head, the other used, both stock 928S . I have the possibility to do the porting plus new seats and valve guides in my company together with an experienced engine craftsmen .
Further I have to calculate shipping costs for 2 heavy parts from AUS plus 25 % customs & VAT for import .

But of course your offer is very interesting , two well-made heads could save me a lot of work, if suitable for still normal street use.

Greg, if its ok for you I'll contact you somewhen the next 2-3 weeks for further information .

Regards
Thommy

Vilhuer

This solution has been talked in here previously. I believe it was done to one German race car and it lost its engine despite the change. Alex in UK has it now IIRR. He should know more.

928@AMG

Hi Erkka,

are there links ? Forum search gives too many hits .

Thommy

Vilhuer

Read this thread, lots of oil issue talk in there:
https://rennlist.com/forums/928-forum/245859-drilled-crank-thoughts.html

Its not racecar Alex has now but German race engine did have failure despite the fix:
https://rennlist.com/forums/928-forum/245859-drilled-crank-thoughts.html#post4652105

928@AMG

Hi Erkka ,

many thx, lot of stuff to read ;-)

Thommy

Steve Cattaneo

Have you looked at other power opinions, any salvage yards in your area that you can buy an AMG 5.5 engine, ECU and Wire Harness. Stock Torque 516 lb. ECU Tune, exhaust and bigger intercooler over 600lbs of torque.

It should be easy to find an AMG engine living in Germany

928@AMG

Hi Steve,

an AMG V8 engine wouldn't be a problem for me to get - I'm working at AMG / Affalterbach:-)
But our engines are not cheap...it would be still ****ing lot of work to transplantate them into a 928.
And if , I would prefer our 6.3 V8 M156 510 hp...but I don't want to spend 40.000 $ only for the engine!

No thanks, I want to keep the look of the 928 engine all stock .


Thommy