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Got my new clutch setup in the car and finally got a chance to hit the track. The weather was great and track prep was fantastic.
The new clutch from Cale Aronson at Black Magic Clutches uses an aluminum flywheel, is 11" vs 10.5" and has a different combination of springs, levers and centrifugal weight. It was designed to allow me to come out of the hole a lot harder with the proper slippage than I could previously and still be able to lock up and hold the power down track.
I had no idea where to begin with the "tune" of base pressure to go along with the large amount of counterweight I had installed. Cale suggest "7 turns" on the adjusters to start out high and then back down as needed. I initially set it up that way...but decided to drop it a full turn to remove some pressure considering I didn't know how track prep would be. I also started with the power turned down by pulling a lot of timing.
They had some "roll racing" there too...which I had never tried. But it's a good way to ck on the engine tune and see how it's going to act. I wasn't sure the clutch was going to like it...but it worked perfectly there too. On the first attempt we "hit it" at about 40 MPH or so. I had it in second gear at around 4000 RPM...it took it OK and pulled through at about 146 MPH at the end of the 1/4. On the next try I added a little fuel to it...as it looked a little lean on the plugs. It responded well and picked up about 6 MPH at the 1/8th mile point....but my hand slipped off the shifter when I pulled 4th gear and only showed 141 mph. BUMMER! (note to self- wash oil and grease off hands better after messing with plugs!). Next try I kept it in first gear at the 40 MPH or so hit at about 5000 RPM...it really liked that! Hit 150 MPH this time!
Later I got first chance to try a launch and do a 1/4 mile pass. I came out at about 4000 RPM and made all shifts at 7500 or so RPM. Ran a 9.44@146 MPH. Not strong on big end...but I still had it dialed down.
I was only going to get one or two more runs in so I added some timing (which it always loves!)
Long story short...launched at about 5000 RPM....and made shifts close to 8000 again and it ended up with the 8.89!! Still not as strong on the front half as I like it...but it was a freight train at the end once everything came together!
That is awesome a Jim! Knew it was just a matter of time. You now have hit an impossible trifecta. Two thousand mile trips, 200mph club, and now runs 8’s. Incredible! Will you have to change the clutch settings for street driving? Where do you think were at horsepower wise with boost settings on that run?
It's a 9.0 compression 555 with twin 68mm turbo's. 5 speed G-Force GF5R trans and 3.07 rear gears in a custom Dana 60 IRS setup. Turbo's are relatively small for this many cubes and RPM....but they package easy and are great on the street. No lag for sure! Using about 17 Psi of boost. It's same basic engine I've ran for 19 years now...just swapped pistons and cam to go turbo instead of N/A.
It's been a long time getting it to launch and hold the power with the turbos...the new clutch was the magic potion I needed. Definitely not a science out race car...just a basically stock Vette with parts added for power and longevity...and weight it seems! Still has leather interior, soft top under the hard top and double insulation under carpet, P/S, stock heavy radiator etc and fixed steel flex fan. I ran 200 MPH with it at the TX Mile last year in basically same trim except for tires/wheels. Last night I swapped street tires back on and went to a little cruise-in we have locally.
That is awesome a Jim! Knew it was just a matter of time. You now have hit an impossible trifecta. Two thousand mile trips, 200mph club, and now runs 8’s. Incredible! Will you have to change the clutch settings for street driving? Where do you think were at horsepower wise with boost settings on that run?
I was using about 17 psi...On this many cubes and RPM the little dudes are spinning to do that...I've pushed them to 20-22 in the past.
I wasn't on my crazy settings since I was trying to test clutch combo...but Wallace calculators show about 1040 or so RWHP for the mph. That aligns pretty close to old dyno readings when set like it was.
I was using about 17 psi...On this many cubes and RPM the little dudes are spinning to do that...I've pushed them to 20-22 in the past.
I wasn't on my crazy settings since I was trying to test clutch combo...but Wallace calculators show about 1040 or so RWHP for the mph. That aligns pretty close to old dyno readings when set like it was.
It's ran 161-162 MPH in the past with a hotter tune...so IF I could use that power and hook it up...might be a little more. But right now I'm happy with where it is..I just wanted to see an 8.99. Not planning on shooting for 7's or anything. I could throw on some bigger turbos and certainly add a ton of HP...but that's going to get tougher to package without cutting on stuff.
11-04-2019, 12:23 AM
Finally!! In the 8's!!
