Rebuilding My 930

[350HP930]

Three things are primarily responsible for power . . .

1. Compression, base + boost in my case

2. Cams

3. Plumbing Efficiency

As you can see I am maximising all of the above. To expect me to leave a couple easy HP on the table is ludicrous.

I am not running really high spring pressures since the engine will be kept under 7K RPMs so there are going to be no undue valve train stresses for me to worry about. Its not like the valves are opening up that much more than they did from the factory.

[snowman]

My point is you are NOT leaving ANY HP on the table. YOu have 800HP heads on a 600HP engine. Why not back off on an obvious extreem wear factor and match the heads to the job at hand?

Actually you have 800 HP heads at 0.4" lift, so say again why you need -.5" lift?

And if you up the boost enough you to can do what BMW did with a 1.6L 4 cylinder engine and get over 1300 HP.

[camgrinder]

.490" Valve lift is not an obvious extreme wear issue. The factory C2/C4 engine has .470" intake lift and that engine has little trouble with cams at 100k plus. The factory 3.8 RSR cams have .490 lift....
The only extreme wear issue I have seen is plugged oil lines or someone neglecting to change the oil.

[briankeithsmith]

I am not running really high spring pressures since the engine will be kept under 7K RPMs

That's what I said until I missed a shift!!!!

Brian

[snowman]

Originally posted by briankeithsmith
That's what I said until I missed a shift!!!!

Brian

Excellent point. The factory engine generally will not instantly zing up to 9000 RPM like a well preped race engine can. So you should plan for this inevitable problem with adequate margins in valve spring performance. My race engine was designed to shift at 8000 rpm but I know it has seen 12000 rpm during one of these events (missed shift or brain fart or whatever). It survived without any problem. Also known to happen is to put the thing in 2nd gear when aiming for 4th on a downshift. What should have been 6500 RPM in 4th is OH MY GOSH rpms for a short time. Instantly tears guts out of the clutch but engine has survived-so far.

[350HP930]

Its a bit difficult to misshift a 930 tranny between the big H pattern and the fact that the synchros become even more difficult when you want to really spin up the clutch disk by shifting from 4th or 2nd to 1st or 3rd into 2nd.

[briankeithsmith]

3rd to 2nd going down the back straight at about 120mph.

Brian

[snowman]

If Youall don't beleive in a missed shift youall havn't raced it yet.

Not to worry, youall will be a beleiver, soon nuff.

[briankeithsmith]

yeah it only took me about .25 seconds to make that shift from 3rd to 2nd when I intended to go to 4th...

Easier to do than people think...
And I was going in a straight line down the straight.
Just a simple slip.

Brian

[snowman]

I found an "80lb super heavy" spring in the shifter helps some.

[briankeithsmith]

Can you elaborate on the spring. Show me what you have in mind?

I'm currently considering a totally new shifter anyway.

http://www.hargettprecision.com/ProShifter.htm

Brian

[350HP930]

Misshifts are usually always related to whats above the shifter knob, not what's beneath it.

[briankeithsmith]

Oh I'll be the first to admit that I wasn't paying full attention. I was in a new car, on a new track so I had my eyes/ears senses pointed everywhere else except my shifting...

Brian

[snowman]

Its been a long time since I bought it but Weltmeister has or had an extra spring that could be added to the shifter to make it a much more positive move if down shifting. Well wortht he few bucks it cost.

I noticed our forum sponser has several shifters for sale. I cannot vouch for any, but maybe some that are familiar could pitch in.

I used to be amused by the shift gates used on Ferraris, but now that I am older and wiser I can appreciate them much more.

And yeh, its whats above the shifter that does the deed, but sometimes you need all the help you can get. That buzz you get racing makes the normal shifter spring feel totally dissapear and next thing you know is you blew it, again, untill you have raced a bit you cannot apprecitate what I am saying. And tracking is NOT racing its a couple of steps and a few cups of buzz juice short.

You can save yourself a few big bucks and just beleive it or find out the high bucks way.

[strokher racing]

Brian, GJF recently installed Mark hargetts shifter. You should read his comments about it. He thinks the world of it and that is saying something since it is coming from him. I saw some more of his cnc work Friday and I can say that he produces a quality product no doubt

Eric Hood

[350HP930]

Since I was planning on balancing the clutch and pressure plate anyways I decided to do a little additional work to lighten up the rotating assembly a few pounds.

Lets just say that there is certainly a bit of extra meat you can remove from a 930 pressure plate without compromising its structural integrity.

The extra surface area and passages should also aid clutch cooling too.

[snowman]

Looks beautiful. Do you champher the edges? I haven't seen anythng on shot peening in your engine. Did you shot peen the crank? The flywheel? Rocker arms? If not I would suggest Metal Improvement Company, a nationwide high tech, mostly mil spec, company with reasonable prices.

http://www.metalimprovement.com/

A side note: This is a subsidary of Curtis Wright, the real inventor of air cooled engines. Glen Curtis http://www.linkny.com/~curtiss/

http://glennhcurtiss.com/
museum has on display an air cooled engine that looks just like an early VW engine. Date approx 1925! Invented, Designed and fabricated by Glenn Curtis. The original fastest man on earth.

Even better they have a Laser peening process, the ultimate method to get all you can get out of your parts.

And finally, having gone as far as you have on an engine, Coatings should be considered.

Have the valve springs coated, the heads(combustion chamber, and ports) the valves, the pistons and skirts, and the headers. Especially important with any super or turbo charged engine.

[350HP930]

We have a shot peening machine at work but I have decided not to use it on any of my parts.

I did debur the edges of the holes I put in my pressure plate which has added a bit of chamfer to the edges.

I have also been busy this week on some remaining clean up and rebuilding issues.

Since strokers powder coated bling posts have been impressive I have decided to work on my own bling by polishing my engine case with the most attention being given to the sections that will be visible once the engine is assembled. There are still some swirlies that need to be taken care of before I move on to the final stages but that' one of my chores for today. Its a shame that most of this will only be visible from underneath the car.



I also would hate to bolt that up to a grungy looking transaxle so I also cleaned it up a bit. Here are a before an after pic to show the transformation.

[350HP930]

Even though my transaxle is still in great shape I am replacing my ring and pinion with the 8:39 set from andial so I figured I would give the whole tranny a rebuild 'while I am in there'.

So far I have pulled the pumpkin and disassembled, cleaned and visually inspected its components.

Since I have limited slip I wanted to make sure the friction disks and other components were still in good shape.

Fortunately the clutch pack, spider gears and everything else was in great shape so its good to know I don't need to do anything but put it back together after I have a chance to magnaflux a few critical components.

I took my camera into work that day so I took a few pics to share with everyone.

Here is the pumkin


And here are the greasy grimy guts


And here is everything all nice and clean. Its great having access to an industrial parts cleaner.

[beepbeep]

Thanx for nice pictures of LSD innards. Never seen them in person before actually ;-)