weedburner

Keep in mind that being able to hold the torque of 1000rwhp is just one part of what you want the clutch to do. You also need that clutch to be able to slip long enough to prevent a bog without overheating. If a clutch/flywheel was designed primarily for road racing or circle track applications, chances are it's to do poorly at the dragstrip.

HioSSilver

iTrader: (8)

Meh....it just takes different techniques.

SLOW SEDAN

iTrader: (13)

Dont have any plans to slip it, hit it hard and fast off the two step and keep wheel speed up off the line. I've seen plenty of guys run the tilton triple fast at the drag strip but they are often in lighter cars. So far it's held up well on street pulls with limited power ~800 or so and feels much better then so called drag racing clutches. I have a friend running the tilton twin and it held enough to carry the front wheels off the line.

SLOW SEDAN

iTrader: (13)

I agree with that. Certainly takes some getting used to, and I've noticed the clutch talks back to you. If you don't rev match perfectly or try to slip it to get into a parking space it makes some noise. But its held two step launches perfectly and WOT shifts are awesome. Curious the lifespan of these disks at this power level, but for the cost of them its hardly worth worrying about.

weedburner

It's agreed that a smaller/lighter clutch absorbs less power as it accelerates, but that advantage fades away at the dragstrip when a heavier clutch is able to spend more of it’s time slipping.

Probably the best examples of this can be found among the manual trans Coyote Stock racers. These cars weigh 3175lbs and have factory sealed engines, spec fuel, spec trans/ratios, and identical ecu tunes. They use 4 gears in the trans, are required to run a 10” single diaphragm clutch, and are required to use the clutch pedal on the shifts. Despite the “heavy” clutch and no clutchless shifts, the fast guys are beating the "1320/mph = optimum ET" thing by a tenth or more. Ask them where the magic is, they will say it’s in the bellhousing. Watch their videos, there is little to no tirespin, the clutch is doing most all the work. No way a small clutch could stand up to that much slipping.

One of my Coyote Stock customers running a 10" single diaphragm clutch using controlled slippage behind the factory sealed 420hp engine that you can buy from Summit for $6700.... 1.256 60'/5.975@113.03/9.484@137.72

Basically a clutch using controlled slippage can allow an engine to operate at a higher average rpm, which in turn allows the engine to make more power within a given time frame. You do waste some of that added power due to an increase of heat produced due to added slipping, but power is being added at a faster rate than the loss from slipping. Net gain overall of power that makes it's way to the track.

SLOW SEDAN

iTrader: (13)

I don't have any desire to slip this clutch or any other clutch with 1000hp or perhaps more. Sure at 400hp who cares you can pretty much do whatever you want and not toast the clutch, but to find a clutch that will allow slipping with over 2x that power is rare and usually doesn't have any longevity. I've tried slipping other so called 1000hp rated twin disk clutches and it turns them to smoke. I'd rather let the tire take the hit and even if it spins on a slick your still going forward at a rather impressive rate of speed.

Darth_V8r

iTrader: (4)

Only one I could think of that could possibly take the slipping and that kind of power is the RPS Billet Cover triple disc.

One thing I found interesting is that RPS is claiming IMPROVED 60' times at significantly lighter weight.

weedburner

When you "let the tire take the hit" with minimal clutch slip it might seem impressive, but you are giving up a lot of ET.

I have a #2800 10.5" diaphragm with a single disc can handle 1000hp with controlled slipping. Steel flywheel and heavy full face iron disc, it's no lightweight. Disc has some life left at the end of the season.

weedburner

I have customers that have melted carbon triples. The discs may be able to take a lot of heat, but low mass equals quickly rising temps. Basically the springs lose tension as it heats up and you lose the ability to hold power down the track.

SLOW SEDAN

iTrader: (13)

Define a lot? We have 4000lb manual cars running 1.4 60' so how much would that improve slipping the clutch? I don't see a car on the manual list at that weight going any faster with any technique. Even the ones 1000lbs lighter barely go .1 faster.

What's the ET/MPH and race weight on that #2800 10.5" single? How many passes a season?

Darth_V8r

iTrader: (4)

OK. The carbon itself should be fine, because it can handle 6000 degrees, but I didn't think about the springs.

SLOW SEDAN

iTrader: (13)

Either everyone around here with an RPS triple cant install a clutch or they are junk. I'm not impressed with the multiple failures I have seen from them. If you want a carbon triple why not just go straight to Tilton? They invented it after all. I don't get why import guys can go fast with these little Tilton clutches and its something of a black art to domestics? They do the same thing we do, build all the boost off the line and send it.

weedburner

It consumes a lot more energy spinning two tires to keep engine rpm up than it does to slip a clutch to achieve the same goal.

MPH is a general indicator of how much power you have to work with, ET is a general indicator of how efficiently you are putting that power to the ground. Don't be impressed when you see an ET with a high MPH, it's a sign that the combo isn't very efficient. I use the old target formula of 1320/MPH=ET to get an idea of how efficient a combination is. Most of the cars on the fastest 6spd list come up quite a bit short, but the fast man trans Coyote Stock guys using clutch slip to their advantage are beating that formula by a tenth using "heavy" clutches.

SLOW SEDAN

iTrader: (13)

lol, I could care less about energy or efficiency as guys racing 4k lb pigs are already doing it wrong. If I cared that much I wouldn't have started with a family car.

Back to the details behind that single disk you spoke of, throw some facts behind that.

weedburner

17lb steel flywheel, Ram 2800lb diaphragm PP w/ nodular plate, Ram 10.5" full face solid hub 5135 iron disc, clamp pressure is buffered with a ClutchTamer.

HioSSilver

iTrader: (8)

That's not a coyote stock car running 9.4s

Tilton ftw!



What it comes down to is there is more than one way to skin a cat. Weedy is from the furd world. Lets face it......their engines leave something to be desired. So they rely on inertia to get down the track. Not the first time I've seen a furd guy claim the heavier clutch is faster. It narrows up their power band to the point the clutch is not coupled much except for a x hundred rpm in each gear. It's almost a tq converter.

Now hopefully at some point this year I'll get to try it both ways. But there is not much doubt with a engine willing to accelerate which way will work the best. Because all that heat weedy is talking about is also wasted energy. That energy could be used to propel the car forward with a lighter more efficient set up

weedburner

If you follow Coyote Stock, the car that posted those numbers has distinctive checkerboard paint/wrap.

Sometimes you have to waste some power to make even more power.

"Weedy" here doesn't even own a Ford, but many of my customers do. My personal power of choice is 355" of old school SBC. 42lb crank, aluminum rods, 340cfm Brodix -11 raised runners w/ titanium valves and shaft rockers with a 2 stage cross hair plate. It's willing to accelerate

HioSSilver

iTrader: (8)

Ok....now we're gettin somewhere. You've already reduced your rotating weight in your engine quite significantly. I can see your preference towards a heavier clutch than i run. It's very likely with all the internal weight you have gotten rid of that yours and my actual rotating weight including the clutch is very close.

Btw i think about a 25lb clutch/fly combo is probably the overall sweet spot for a street drive ls car. Probably for furds to since they're cranks are similar weight.


Coyote stock stuff record is a 10.0. It's easy to find. Maybe there is another class idk or he went outlaw. I've seen you post info from furd cars.

SLOW SEDAN

iTrader: (13)

No, I wanted ET/MPH and race weight.

big hammer

And a 2400 lb raceweight. And the guys running 9's are not even close to coyote stock trim. Coyote stock record is in the 10's.

A 2400 lb RW can solve a lot of things for a lot of people