hopwood

Can someone explain to me why this wouldn't work with CIS injection? Using a Euro S 4.7 bottom end.

Thanks

Joel

Lizard928

It will, but you will need to use the center plenum from your current setup. And you will need to hog out the center plenum tubes.

Iwanna928

One last question before I fiqure out what I am going to do to my car.

It sounds like a larger shortblock would work better w/ this combo. That being said would a 85/86 5L block work better than a 4.7, put out more power?

Would one motor be better for putting in my 79 than the other?

Would a later model 5L shortblock be a better choice or should I look into a 4.7L euro shortblock for performance?

Thanks

Stephen

James Bailey

That is MORE than one question and way more than one answer..... more displacement makes more power. Using the 85-86 short block REQUIRES notching valve reliefs into the pistons which means taking the engine all apart. After you do the full monty on the 16 valve you MIGHT get 300 hp at the rear wheels with big race cams Euro parts etc. etc. or just about what you get from a good S-4 engine with headers no cat.

slate blue

Jim your pretty correct, I can go one more with straight up empirical evidence, my 5.0 2V euro with S cams, cleaned up modified S intake adapted to electronic injection, my headers and custom exhaust did 305 rwhp and a S4 manual with X-pipe did 279 rwhp. On different days etc but I am sure that S4 runs strong as the one that went on the same day as mine a 90 MY auto did 250 rwhp and was a good engine too. My 4.7 L when it wasn't running right did 277 rwhp on the same dyno.

I will next year money permitting figure out what is holding the power back. I firmly believe that the 5.0 litre engine I have can do around 330 rwhp, it has done a best of 311 rwhp so far. The thing is, it makes the basically the same power at 5000 rpm as it does 6,000 rpm. i.e 300 rwhp vs. 305 rwhp. The redline is around 6,700 rpm and I would like to see peak power at 6,500 rpm. I have to say it is real easy to drive with the linear power all the way through the rpm band.

Terry when are we going to see this portwork?

Greg

Iwanna928

If I wanted to buy an S4 with headers I would have. I just prefer the OB. It is old and crude like me! It is lighter, and I like the sound of the 16v.

300rwhp would be just fine. I am sure the car will be a blast at that level as she is already fun w/ 203rwhp!

Sound like the shortblock should be a 5.0L 85/86.

Stephen

James Bailey

Note that using the 5 liter pistons with limited valve notches makes it an interference engine.....(valve bender ) which negates one of the nice things about 2 valve engines. Yes 300 HP will seem fine until you get accustomed to it and then just like the boosted boys you will want MORE ! Have fun that is all that matters. No one NEEDS a 928 we just WANT them.

dprantl

400rwhp is not enough...

Dan
'91 928GT S/C 475hp/460lb.ft

Iwanna928

Actually, Doing some more research it doesn't seem to make much sense to go w/ a 5.0L considering the machine work that is needed. A 4.7L seems like a better fit. Will lose a little hp but the money saved can go toward S4 brake conversion.

It seems that the 4.7L rings aren't that expensive, compared to 4.5L and just get the bearings and gaskets and refresh the engine and bolt her together.
Maybe a euro 4.7L?
I think the whole thing could be done w/ around a 5k.

Stephen

BC

The difference from 4.5L and 4.7L properly intaked and exhausted is not that large. Of course I am biased: You sure you don't want my 4.5L?

danglerb

I will never put anything smaller than a 5.0L bottom end on any 928 motor I put together. Without the 12% or so HP gains the 4.7 vs 5.0 has you end up stuck in that less fun less power 270ish rwhp even with a Euro top end.

Plus you don't need S4 brakes unless you plan on driving a very aggressive brake demanding track.

Iwanna928

So I just noticed that you could make this work with CIS and you could use unwired tools CIS mgt system with it?

Stephen

Iwanna928

Bump for making this work w/ cis. Does it require the same as the questioned answered in regards to the 4.7. I would need to hog out the plenum of my 4.5L?

Thanks

Stephen

terry gt

Still for sale

tv

That package sounds awesome, all the right parts, and great rpm figures

There is a mystery though in the many attempts for more power, Carl fausett thought so and felt it was the plenum. I have been reading all these threads about this quest for more power going the N/A route. Just above, Greg mentions he gets no gains from 5000 to 6000 rpm's.

And it's got to be explained in this thread - https://rennlist.com/forums/928-foru...and-video.html


These heads flow - the 4.7, the exhaust flows, the rpm's are there on some of these projects are great. It is not explained by displacement, because that thread above disproves that. And these new cars disprove that;
Aston V8...........4.3 lt.......400bhp @ 7000
Audi R8............4.2 lt....420bhp @ 7800
BMW M3...........4.0 lt...... 414bhp @ 8300
F 430...............4.3 lt.....483bhp @ 8500
Maser GTS .......4.7lt......440bhp @ 7000

The missing link has got to be the expert tuning. In other words the new maps, which can be done now.


That's why I think the 4.7 is ideal for a high revving, high power N/A set-up. And Terry, I think the parts you are selling are perfect to achieve this and I hope you don't mind me posting my thoghts here but it seems the place for it.