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-   -   Finally!! In the 8's!! (https://www.corvetteforum.com/forums/c3-tech-performance/4337400-finally-in-the-8s.html)

427Hotrod 11-04-2019 12:23 AM

Finally!! In the 8's!!
 
8.89@157 MPH!

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!

Been a long time coming!

JIM

PS- Been waiting to install new plates!
https://cimg1.ibsrv.net/gimg/www.cor...959f85a1e6.jpg

https://cimg1.ibsrv.net/gimg/www.cor...d1cd59de9f.jpg
https://cimg3.ibsrv.net/gimg/www.cor...1ec7762624.jpg

Daveinspain 11-04-2019 04:05 AM

Impressive , congrats...!!!

bjankuski 11-04-2019 05:57 AM

Impressive, what is the combination?

Gordonm 11-04-2019 06:12 AM

Jim, always impressed with you and your car. Really hauls butt!

derekderek 11-04-2019 06:17 AM

major league pitchers use a rosin bag. you qualify as major league...

69ttop502 11-04-2019 07:13 AM

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?

L88Plus 11-04-2019 07:31 AM

From those of us who follow your ride, AWESOME...but it was expected!!!

resdoggie 11-04-2019 07:58 AM

Now go out and get that new plate on! Well deserved. BZ!!!

Jeffs82c3 11-04-2019 08:15 AM

Congrats Jim.:cheers:

stingr69 11-04-2019 08:22 AM

I gotta get a new clutch. :eek:

OMF 11-04-2019 09:06 AM

Yes, as others have said you worked hard for this, congratulations!
Now we need a vid......

chevymans 77 11-04-2019 09:43 AM

Congrats Jim,

We want videos

Neal

427Hotrod 11-04-2019 12:12 PM


Originally Posted by bjankuski (Post 1600433584)
Impressive, what is the combination?

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.

https://scontent-dfw5-1.xx.fbcdn.net...43&oe=5E459CDA

427Hotrod 11-04-2019 12:19 PM


Originally Posted by 69ttop502 (Post 1600433726)
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.

JIM

427Hotrod 11-04-2019 12:22 PM


Originally Posted by chevymans 77 (Post 1600434358)
Congrats Jim,

We want videos

Neal

I hear there's some of the roll racing...don't have them yet. Hopefully some buddies got some....

JIM

Jebbysan 11-04-2019 12:35 PM


Originally Posted by 427Hotrod (Post 1600435285)
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.

JIM

How much do you think is left?

Jebby

427Hotrod 11-04-2019 08:49 PM

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.

JIM

ajrothm 11-04-2019 09:21 PM

Congrats Jim!! You FINALLY got it there!!

Looks like there is still some left in it too.... Nice job as usual...

Buccaneer 11-04-2019 09:27 PM

Very nice indeed!! Congrats. :thumbs:

claysmoker 11-04-2019 10:08 PM

Nice shifting!!!:thumbs:


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