toofast928

Ok so with a bottom end truss, solid crank and head studs the 4.5 or 4.7 is good for 450HP (flywheel). cool............

karl ruiter

Carl
You could probably modify the WUR yourself. My '79 was all out of wack when I got the car and a rebuild unit I got from one of the big three did not work. If you disassemble the unit you will see there is a chromed rod which activates the pressure valve. If you go to the hardware store and get some 16th brass rod you can cut a new rod. Start out slightly longer than the old one, assemble test, disassemble, file, and repeat until you get the behaviour you want. It took me a few hours the first time but with practice it could be quick and easy. A few mills change in the length of the rod makes a big difference to the behaviour so you kind of have to go slowly.

mark kibort

Ithink your right!..
as far as injectors, no i never changed them through all the mods from 175 at the rears up to 293hp at the rears! fuel curve was very nice too, in the 12.5 range all the way up to redline. (maybe 13:1 at redline) pressure was up to 52psi or so, and duration of the injectors was in the 90% range at at near redline.

one fuel regulator is all you need. (clamp off the other one!)

mk

Fastest928

Jiohn,
Yes, we used the 85/86 headers and with CIs managed the 310. Added EFI and pinched out another 10 rwhp. This was a high precision blueprinted engine.

I think your 305rwhp is right on the money....

hacker-pschorr

kibort,
When you clamp off one fuel regulator - is one stock one enough or do you need to upgrade the single injector to a different unit?

Carl Fausett

karl - part of the issue is the many varieties of WUR their are. There are Euro models, US models, Lambda models, not Lambda models, Hi-Altitude models, and vacuum-assisted models.

Then, I got the nuts in Great Britain that modify their WUR - adding an allen-screw adjuster to the think so they can set it where they want it! Cool!

slate blue

Is there any headflow figures out there for the 16 valve engine? I have some for the standard euro heads but would like to find out what people are achieving for the fully worked heads. I'm not interested though in increasing the intake port size, standard size is 42 mm, this should be adequate.

I have an article from many years ago, it was in excellence, it has the start of Porsche 928 develpment in it, the beginnings of Devek. They accidenlty over revved an engine and got something like 710 hp. Now I don't know whether the dyno went crazy and gave an inaccurate reading, because those heads would have to flow some serious numbers to produce that power. I estimate around 350 cfm @ 28 inches.

The issue with that is, the standard flow figure @ 0.500'' is 210 cfm, that is a long way off. My guys were talking about achieving 270 cfm which should support 550 crank hp. Is there any knowledge out there on this subject?
Also does anybody on the list sell head studs for the 16 valve engine?

Thanks Greg

Jim bailey - 928 International

Greg I believe there were some inaccuracies in that article about the actual power, I actually watched that car run at the track. I think the most Mark Anderson ever had out of a two valve (extensively ported with oversized valves) was about 425 hp out of a 5 liter but that was so long ago and on CIS Euro intake extrude honed big cams at 7,500 RPM or so. The typical "mouse motor" hybrid 5 liter16 valve race engine is putting down around 300 to the rear wheels.

FBIII

In 1990 a Devore 6.2 liter 2 valve reportedly made a little more than 580hp. There was a write-up about it in the August 1990 Excellence magazine. Internally it ran chevy dimensions, a 4.155 bore and a 3.48 stroke. I never read anything about his 710hp engine but have heard the rumors. He ran steel liners pressed and epoxied into the block that didn't limit him to 104mm. I think he was limited more by the crank which was welded to achieve the greater stroke. He ran huge valves enabled by his much larger bore and opening of the combustion chambers.

slate blue

Thanks very much guys for your responses, it also helps Jim when somebody can say I was there! Has a certain weight to it. Great info from somebody who has been there done that.

FBIII you have a great memory, when you stated those facts, I did seem to vaguerly remember them. Is all the interest in the 4 valve motor now? The reason I say this is that, my 4 valve project has been shelved for the time being due to cost limitations. You need custom everything and userly 32 of them.

I have found the 16 valver is much cheaper even for my miserly budget. Have some great ideas for it. Will hook up the dry sump I bought recently, I am also buying some Ferrea nascar valves for the heads. We are close to the 270 cfm mark now, and with the lighter valves, springs and retainers I believe 7500 rpm is a reasonable redline.

I also will be using the 5 liter bottom end with custom internals, does this block already have studs? If so can I use them with my early heads?

Cheers Greg

Jim bailey - 928 International

Greg one thing I have in excess is ...weight Bud Hart was Bob Devore's mechanic and built the engines. I had the opportunity to talk with him at length several years ago when he visited our facility.

BC

You can buy studs for the early 5.0 blocks from ARP I think. the 944 gusy use arp all the time.

slate blue

Hey Brendan, do you have a ARP part no.? Also will the factory studs do the job in the 5 liter bottom end?

FBIII

Greg not a great memory, I'm just reading most of the things from the magazine. Its one that I will never throw out. I wish there was more interest and development in the 2 valvers. I'd love to see a 6.4 stroker with huge valves, radical cams and an aftermarket injection system. I'd love to see what kind of numbers they would produce compared to the 4 valvers.

BC

Greg - don't know the part number but here you go:

http://cgi.ebay.com/ebaymotors/ws/eB...Name=WDVW&rd=1