weedburner

Much easier with a properly sized clutch, but there are some short cuts...

BALBI

We have a 275-50-15 ET Street R currently. Tough to dial in but here are the results.

Launching at 6,500 on a 2 step. Adjustable shocks set at 2 from full soft up front and 2 from full hard in back. Car weighs 3,850 with me in it.

BlackSS2001

iTrader: (23)

What clutch do you have in the car?

a05c

Radial's do not like to spin. They're deadhooked and apply power. a 28x10.5 slick will work better with a clutch car.

weedburner

The trick is not knocking them loose in the first place, let the clutch do the work.

a05c

Seems counter intuitive to me, if you're letting the clutch do the slipping, why not let the tire (slick) do the slipping. It's less wear and tear on drivetrain parts and tires are cheap in comparison.

Trust me, I know what a radial wants.

01ssreda4

iTrader: (96)

Not trying to be a dick, but if 10s seem easy why are you stuck in the 12s? And whats so hard about finding one these cars you speak of and copying their combo?

The bottom line is this, ive taken my car from 12s down to 10s on motor. It took me at 3000 pounds, H/C/I, gear, suspension, big *** converter, rear end, driveshaft, slicks you ******* name it. Its not as easy as some make it out to be, that I can promise.

weedburner

When the hit of the clutch is matched to the engine's power, it becomes equally easy to run either slicks or radials...with less wear/tear on the transmission and rearend. The clutch disc does become the wear item, but that's more than offset by longer lasting tires and the ability to run the same radial tires on both street and strip. Add to that the fact that radials can be quicker/faster on a 10 sec car, there's not much reason to keep choosing slicks.

I've got quite a few really quick Coyote Stock customers that are required to run slicks, single disc diaphragm clutches and factory sealed crate engines. They have found that tires slipping less and clutch slipping more makes the cars quicker/faster and more consistent. Here's a comparison of one that used a conventional wheelspeed based launch in 2015...
1.362 60'
6.257 @ 110.56
9.84 @ 135.69
Exact same car and exact same factory sealed crate engine in 2016 using controlled clutch slip...
1.256 60'
5.975 @ 113.03
9.484 @ 137.72
People ask why only 137 mph with a 9.484 et?...super efficient launch with basically the same engine HP.

The clutch is simply capable of a higher slip rate than a pair of slicks, and still able to recover. That gets you a higher average engine rpm and increased power production within a given time frame. Coyote Stock guys could be even quicker if they could switch to radials, but the rules won't allow it. In the Factory Stock class where they are required to run radials, the fast guys are clutch guys exploiting clutch slip, while the automatic guys get a 100-125lb weight break.

How is it possible for a less efficient mechanical coupling (slipping clutch) to increase your engine's power production? Here's a simplified example- lets say a car has the power to gain speed at an average rate of 6000 rpm per second in 1st gear. Let's also have the clutch slipping until 0.5 sec into the run with the tires remaining dead hooked (i like radials). If the car launches at 6000 and the tires are stuck, that clutch will pull engine rpm down to 3000 by the 0.5 sec mark. Rpm then begins climbing from 3000 as it recovers lost rpm, to 6000 rpm by the 1.0 second mark. During the initial 1 second after launch, the engine's average rpm was 4500, which means the engine made 75 revolutions over that 1st second of the run.
...Now repeat the launch, but with the clutch slipping just enough that the engine does not lose any rpm at all over that same 1 sec period. Now the engine's average rpm has increased to 6000, which means it made 100 revolutions during that same initial 1 second period.
...The launch that didn't lose any rpm actually packs 33% more revolutions of WOT power production into the same 1 second time period. If the clutch also slips just right after the shifts, you can pick up a little power production there as well. You might lose a little of that 33% gain due to increased slipping, but there’s a lot left over to make the car faster. Balancing a small loss of mechanical efficiency against a 33% increase in power production can result in a HUGE net gain!

sillysspeed

iTrader: (21)

very true these things don't go 10's NA by just slapping something together. You have to plan it all out with good parts, good driving and atleast some strategic weight loss. It can be done but you better be dedicated and willing to give up some kinda driveability and or creature comforts.

01ssreda4

iTrader: (96)

I absolutely agree. My combo (tame and streetable H/C/I) was a 11.5 combo. Ive chipped away another .6 so far by working really hard to optimize everything when time and budget allows. Now, the car remains stock looking but weighs UNDER 3k, has ZERO creature comforts other then power steering/brakes and stock appearing interior. I even tow to the track now everytime bc im on slicks. While it can still be driven just about anywhere, who'd ******* want to!

Tuskyz28

If I was in your shoes I'll dive heads first. Go with a proven cylinder head such as a TFS or a AFR with a cam to match. The MS4 cam is a big cam for a stock cube car... It's possible to get better performance with a smaller well thought out cam with a great set of cylinder heads and it'll be easier on your valvetrain. ​

If you don't want to invest in heads I would invest in getting a great hooking suspension.

01ssreda4

iTrader: (96)

I definitely agree with this logic.