Race car engine replacement and upgrades

[Red Baron]

The engine swap has started on the race car and I've been doing a few things to upgrade the motor, especially in the area of the 2/6 bearing failure issue.

I ordered the crank scraper and windage tray set up from 928 Motorsports a couple weeks ago. This is a set up made by Ishiara-Johnson and has been tested by Carl@928 Motorsports. I figure if he ran it on a SC car all the way to the top of Pike's Peak, it must be a pretty good set up. Also the Dutch Stallion race team runs this set up. I also traded pm's with a couple of guys running the set up on their track cars with good results so I believe this is a really good upgrade.

In addition, I've pulled the crank from the motor and will be sending it to Taylor Engines for the cross-drilling modification. Also my Accusump is heading back to the factory for a rebuild. All of that combined with the Oil control system from 928 Motorsports should be a good start in solving oiling issues related to the 2/6 bearing failure. It should also greatly help from oil being discharged all through the system under hard driving conditions.

About the only other thing I am considering doing is adding the Aluminum Flywheel from Motorsports. This would reduce the rotating mass weight by about 6lbs and should make for a quicker reving engine and a slightly broader torque curve. I look at virtually every other type of well sorted race car and one of the things they all have in common is a lightened flywheel, so I'm very inclined to go ahead and do it.

In addition to all of that, seals, WP/TB, intake gaskets, vaccum lines, motor mounts, pan gasket and rod bearing will be replaced.

Am I missing anything?

Should be up and going by October and I plan to bring the car to the Rennsport Reunion in November in Daytona.

[Danglerb]

Is there anyone that races a 928 and doesn't have some concern, some added attention to the rpm etc in a hard left regardless of modifications? Who wants to "test" their $28k stroker?

Greg seemed pleased with those metal screens he is making that go under the crank.

If I hadn't found a cheap flywheel I was thinking about using Carl's, supporting the design effort if nothing else.

[rhjames]

a couple of comments:

I just bought a (unassembled) hybrid from Stan Shaw. He has been most helpful with his knowledge, and offered many suggestions.

One of them is that the oiling system in the 928 is lacking for rpm's over 6000. The remedy for this is drilling the crank "like a Chevy", something that Taylor offers and was done to the crank Stan sold me, but to take advantage of this you must use a fully grooved main bearing set. No bearing company makes these straight out of the box, so they must be machined. Stan can give you a lead on getting this done.

If you are starting from scratch on a crank, I suggest all of the usual modifications like knife edging, cross drilling, chamferring the oil holes, chroming of the bearing surfaces (Chrom-a-shaft in Memphis, TN, can get his done for you) or any other crank mod that is currently in the mix for racing applications.....

Another suggestion from Stan is a dry sump system. An Accu-sump is probably a good idea (most drag racers use it), as well as crank scrapers and windage trays.

Another problem (that I have experienced) is the issue of crankcase breathing/ventilation. Sure, it's different between the 16V and 32V engines as far as application, but these engines build a huge amount of crankcase pressure, so letting it breathe without blowing the seals everywhere is something to be worked on. Do you have a system to prevent this from happening? The oil recovery system from Carl works somewhat, but I believe it needs a collection/recovery tank in addition to what's in Carl's kit (I run his kit on my car, but it's not quite enough). I run 16V and the factory breather system is just a joke----my opinion. It does nothing but put oil in the intakes, something that's fine for an oil burner, not a high performance car.

Then we can look into other things like bearing/crank clearances, piston/cylinder wall clearances, piston ring end gaps and such.....Where are you with these issues? Porsche runs quite loose tolerances, compared to iron block engines.

Have you done any block prep like de-burring, opening up of the oil drain holes, polishing/filling/painting of the oil valleys (this is mostly in the heads), etc.????? (many competitive race engine blocks may have hundreds of hours of prep in them...)(same goes for the heads)

The lightweight flywheel is another good direction to go to let the engine rev quicker. Same goes for the clutch assembly as well. Look to the other end of the engine (crank/timing pulleys) for improvements, too. Everything that turns, turns quicker when lightened.

Reciprocating assembly balancing is another performance improvement, even though there is much argument against spending the money to do it (Porsche claims this is unnecessary, but for what little money it costs to do this, I think it's worth the expense.)

Have you thought about a free flowing fuel delivery system? Are you still using the stock pump, lines, regulators, etc., for an engine that may be going to produce twice the rated power from the factory?

Then there's the top end to look at.....but that's another long discussion.


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[Barbapapa]

About the term "cross drilling", it's a bad thing and has only been recognised as bad in recent years so you still hear it pop up as a buzzword. Crossdrilling is the hole going all the way through the main with the passage up to the rods intersecting it at the center.

The idea of crossdrilling is that both ends of the hole in the main will always be exposed to oil pressure with a bearing grooved 180 degrees. The problem is that the oil pressure has to overcome centrifugal force to get to the center, at high rpms that force overwhelms the oil pressure. I've done some casual calculations that have the centrifugal force at 6000 rpms being equal to the force of 50 psi, the higher the rpm the greater it cancels out the oil pressure.

A stock 928 crank is cross drilled. IMO that's the cause of many bearing failures, especially at a steady high rpm conditions. The 2/6 oiling is a seperate issue. A "Chevy drilled" crank has the passages not going deep towards the center, it's not uniquelly Chevy, just a common way of drilling.
Does Taylor plug the 928's cross drilled hole and drill 'like a Chevy'? If so that's good to know. I may want that done if I ever use a 928 crank, please report back.
There was a thread on RL about the grooved bearings necessary when using a properly drilled crank. Devek has sets grooved and presumebly sells half bearings. I set up a CNC mill to groove a bearing 230 degrees and did a set for another build and my own. Beware of some grooving jobs, one was pictured on that thread that was way too small and could have been a problem.

Keep us posted Abby, I can't wait to see your car finished!

[Red Baron]

Yes, they do plug the factory drilled holes and I am looking into the grooved bearings.

Will you be attending any DE's at Road Atlanta? I live about 80 miles from Atlanta and very close to Callaway Gardens. We just moved there at the first of the year and I'm looking forward to meeting other 928 owners in the area!

[Barbapapa]

I plan on being at most any DE or race at Road Atlanta. I live a few miles away. My own racer is coming along, the cage is finished and is being painted now. I've had to take my nice stock 87 to DEs so far and next up is Little Talladega in September. A stock 928 can really scoot and do some fast laps, your car should be a real treat!
There's also the Petit Lemans Oct 3-6, we could always form a little 928 owners camp but it will be crowded and the infield will probably fill up early. Last year was some kind of record and I never saw such a crowd at RA.

[Herr-Kuhn]

Will this engine be normally aspirated or boosted?

[Fabio421]

Abby, are you sticking with the 86 engine and just fixing it or are you planning on updating to an s-4 engine?

[Red Baron]

Barbapapa, I look forward to meeting up with you for some 928 fun!

Herr-Kuhn, NA for now as I work on my driving skills in the DE venue. However, a stroker or boost mod would not be out of the question if and when I truly get into the Club Racing aspect.

Fabio, Sticking with the 85/86 engine as I have 3 of them. The one going in the racer is the one removed from my 86.5 turbo car that now has the low compression motor that was built from the ground up using a brand new block. I also have the motor that was damaged at Sebring last year that was in the car when I purchased it from Constantine. So, I have two 85/86 motors and the custom motor in the turbo car. The damaged motor will perhaps be a stroker build for the racer once my driving skills have improved enough to merit it. You will very likely see the racer at Daytona in November.

Thanks for asking!

[Herr-Kuhn]

Yes...I agree, better top start on track with something that won't kill you. I imagine it would take quite a driver to be able to handle my TT on track.

[Red Baron]

I have to wonder how a non drilled crank completely stock boosted motor would last with a capable driver such as Mark Anderson. My bet is that the TT wouldn't finish the race with Mark at the wheel. LET ME MAKE THIS CLEAR; NOT because of your TT set up but because the motor would need to be properly prepped for the hard-hard driving. A driver like Mark can push these cars to their limit fairly easy and a stock crank would have almost zero chance of survival under racing conditions. jmo

Has the crank been done in the TT?

[Danglerb]

Greg and Mark were talking about the new motor and reliability, and noob that I am I asked them if maybe part of the reason the motor held up so well is that Mark is careful with it. They thought that was pretty funny and Greg made the comment that Mark could break a crowbar playing in a sandbox.

Mark Anderson's first car was a fairly stock, no special crank drilling Euro motor wasn't it?

I'd agree that boost in itself might not have any direct effect on the common failure modes. Maybe it would allow a slightly lower rpm range with sufficient power, that was the case with the stroker motors the race rpm dropped from something over 7200 rpm with the Euro to below 6500 with the stroker. Boost is going to make crankcase pressure more of an issue to control, but I don't know how that might figure into reliability.

Much more power than the current race stroker is going to break some transmissions, third gear seems close to the limit as it is now.

[Alan in AZ]

I 'd agree the PCV/oil breathing is worth looking at for improvement. Seems there is no concensus on any single thing to do but various ideas that seem to have some success. Adopt some of the expanded breather plumbing of the later cars - change the oil pickup, dipstick retention, baffles/scrapers, catch cans/recapture and expanded return ports to the sump...

See what Louie Ott did for some more ideas...

Alan

[Red Baron]

Originally Posted by Danglerb

Mark Anderson's first car was a fairly stock, no special crank drilling Euro motor wasn't it?

Yes, until he fried it

Mark told me that in the beginning of his racing, he was blowing stroker engines so fast that he had to quit using them because he couldn't afford to keep building them. So he started actually pulling a stock used motor off the shelf fully knowing it was going to get destroyed. I've talked to him at length and the only thing he was unsure of, was the scraper and trays. He wasn't sure if they had ironed out some of the issues they initially had.

[Red Baron]

Originally Posted by Alan in AZ

I 'd agree the PCV/oil breathing is worth looking at for improvement. Seems there is no concensus on any single thing to do but various ideas that seem to have some success. Adopt some of the expanded breather plumbing of the later cars - change the oil pickup, dipstick retention, baffles/scrapers, catch cans/recapture and expanded return ports to the sump...

See what Louie Ott did for some more ideas...

Alan

Alan,

I am going to try all of the most simple solutions first. If that doesn't work, I may explore a vaccume. Louie sent me a great email with tons of info and I've read all of the info from his site. Hail King Louie!

[Danglerb]

Several people are trying things, should be interesting to see how it works out on the track.

[Barbapapa]

Originally Posted by Red Baron

Yes, until he fried it

Mark told me that in the beginning of his racing, he was blowing stroker engines so fast that he had to quit using them because he couldn't afford to keep building them. So he started actually pulling a stock used motor off the shelf fully knowing it was going to get destroyed. I've talked to him at length and the only thing he was unsure of, was the scraper and trays. He wasn't sure if they had ironed out some of the issues they initially had.

Did any of his early motors have the crank oiling modified? Did the problems end with the Moldex crank?

What do you mean about being unsure of the scraper and trays and issues, you you please elaborate?

BTW, Louie is indeed 'The Man'.

[Fabio421]

On a race application why wouldn't you use an exhaust driven crank case evacuation system? Has anyone tried one on a 928? I have used one on another application in the past with good results. You just need to keep a couple of extra check valves around in case you burn one up. Those are cheap though.

[MarkRobinson]

Yes, Fabio421 offers a good idea: very common in older muscle cars, but wouldn't work on a turbo car because the exhaust is pressurized.

How about a breathing to atmosphere catch-can & -4an oil-drip return to the plate on the front of the oil pan? That's what I have on my track car, works just fine.

[Red Baron]

Originally Posted by Fabio421

On a race application why wouldn't you use an exhaust driven crank case evacuation system? Has anyone tried one on a 928? .

Yes, Carl has done this and it works well according to him.