bpaspi

Chris, I never thought that the clearance between the exhaust valves and piston would be a problem. Even with High compression pistons
The valve lift in TDC times is only 1/8" It must be very tight in the combustion chamber in TDC.
I need to check this on my actual build. I use the Woessner pistons again.

chris_barry

From memory, at TDC I had 4.2mm available exhaust valve possible movement and about 3.6mm lift. The critical point was 7 degrees before TDC. I had the exhaust cam lobe centre at 102.5 degrees. Advancing the cams to 105 degrees made a huge difference in clearance.

The exhaust valve cutouts in the H22 pistons are in the wrong place so the exhaust valves are just above the flat top of the piston.

If you had pistons with an appropriate valve pocket you would have huge clearances, you can see from my pictures I only took a small cut ( 1.8mm deep) to provide what I hope is safe clearance. Most pistons have much deeper pockets than this.

chris_barry

Latest update, got the car running and on the road to run it in.

Took some time to build a startup program that was close enough for the AEM automapping to trim.

With the larger low lift cams of the Spec C's it pulls like a train off VTEC and doenst run out of puff at 4000rpm like the stroker did with standard cams. Once I hit vtec at 6000rpm it just wheelspins ( even in 3rd or 4th gears). Cant get on a dyno with the local E85 guru till next wednesday. ( day before I head off to Bathurst)

The E85 is an interesting fuel, needs richer than lambda 0.9 to run reasonably, but will tolerate as rich as 0.75 without any fuss. I was aiming for 0.82 mixtures. I was running in the engine at night and it shoots blue/white flames out the exhaust on gear changes. The car drank 30litres in 180km so you certainly notice the higher consumption.

Antonov

Urge

Um, can I donate to a dyno fund?

chris_barry

Thanks for the offer but I'm OK with the dyno. Will be dynoing on Wednesday ( day before I head off to the race meeting)

chris_barry

Had some pictures of the installation that I may as well post up.

I replaced my Exedy uprated clutch with a used Toda flywheel/clutch kit that I machined and fitted a new plate to.



This is a lot lighter and smaller diameter clutch assembly than the stock unit. I noticed a huge difference in wind up/down rates. The pedal pressure is a little higher. It really bites hard, hopefully it will settle down once the surfaces burnish up a bit.

Someone asked about my exhaust. There isnt much off it. The headers are similar to a stock setup except the primaries are 2 inches longer ( trying to broaden the torque band). The muffler is a straight through race setup with 2.5" inlet and 3" outlet, tapered perforated tube inside and stainless sound wool inside.




Fitting the engine is a pig in my chassis. There isn't enough room to slide the engine/gearbox in together. I need to assemble the two in the engine bay with only access from above. Lots of swearing.







Will post back with results after the dyno day.

nsx_bob

wow very awsome! cant wait to see dyno!

bpaspi

It doesn't.
I have it in since 5,000 miles and it's still tricky to engage.

But the clutch is real good on the race track!

rob.ok

Chris, How does your oiling system work. It's dry sump right? Care to give us a little detail on how you went about setting that up? The only bolt on options for the F motor is just astronomically expensive.

-Rob




EDIT: Never mind did a search and found on the first try! That thing must be a rocket......Sweet
http://www.speedracersportscars.com.au/PRBS2K.htm