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Let's talk about lightweight clutch/Flywheel combo's

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Old 03-02-2017, 11:50 AM   #221
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Originally Posted by North*power View Post
I would really like to see a free rev video or two with it! Also would be interesting to see how well idle rebounds from coming back down so quickly thanks to the reduced MOI.
He ya go. Mine is a 5.5 tilton and scotty's is a 7.25 spec. Be similar tho

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Old 03-02-2017, 09:09 PM   #222
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He ya go. Mine is a 5.5 tilton and scotty's is a 7.25 spec.
Haha I had a feeling you'd post something Good Hio. Car sounds amazing with the new exhaust! Being that you have probably the lightest clutch assembly, do you think the driver for the tach is accurate in keeping up with the actual rpm on freerev or lower gears? I've heard that the tach readout can't keep up sometimes. Did it take much for you to dial your idle back in after the clutch install?
I'd love to have your faceplated trans and clutch with a S1 sequential shifter and pressure sensitive shift ****. It would be as close to a full on Emco or similar.
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Old 03-02-2017, 09:14 PM   #223
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Here's mine... pay no attention to the squeak it was a loose rear shock
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Old 03-02-2017, 11:35 PM   #224
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I had two engines that were pretty close to the same but different component weights. I didn't change the weight of the flywheel/clutch itself, but i did change the weight of the overall rotating assembly...

...Engine #1 was 4.04" x 3.48" w/ 5.7" i-beam rods, hypers with gas ported spacers and 1.2mm rings (12lb oil), 49lb crank balanced to a 1863g bobweight.

...Engine #2 is 4.03" x 3.48" w/ 6" aluminum rods, forged pistons with lateral gas ports and 1.5mm rings (14lb oil), 42lb crank balanced to a 1492g bobweight with pendulum style counterweights, drilled rod journals.

Both have flat tops with nearly identical quench and compression. Same intake and carb, same carb calibration. Exact same cam installed on the exact same intake centerline. Same flywheel and pressure plate installed in exactly the same car, same weight, with exactly the same gearing and tires. Even though these tests were a couple weeks shy of 2 years apart, both tests are on the same location with zero tire spin and conditions were very close to the same.

Here's the observed rates that the engines gained rpm WOT...

1st gear 2000 to 4000 rpm- engine #1 1634 rpm/sec........engine #2 1910 rpm/sec (276 rpm/sec difference)
1st gear 4000 to 6000 rpm- engine #1 1975 rpm/sec........engine #2 2217 rpm/sec (242 rpm/sec difference)
2nd gear 4000 to 6000 rpm- engine #1 1070 rpm/sec.......engine #2 1116 rpm/sec (46 rpm/sec difference)
3rd gear 4000 to 6000 rpm- engine #1 535 rpm/sec.........engine #2 541 rpm/sec (6 rpm/sec difference)

As you can see, in the higher gears where acceleration is slower there is not much difference in acceleration rate. But in the lower gears, the differences in rate of acceleration progressively increase.

There also seems to be a quite a difference in no load acceleration rate, but the conditions of the comparison were not the same. I had a clutch linkage experiment go bad in 2014 with engine #1, which resulted in a free-rev condition during a 4000 rpm WOT launch in which that engine gained rpm at an 8500 rpm/sec rate. I was also experimenting with pulling timing at the time for a no-prep race, but my records don't indicate that i was pulling timing on that particular launch.

Under NA free-rev conditions, engine #2 gains rpm at a 11,515 rpm/sec rate.

All acceleration tests are basically inertia dyno runs, even if that test is a no-load test where the only inertia resistance is supplied by the weight of the rotating assy itself. What most people lack is a way to collect accurate comparable data. Even though these tests were conducted almost 2 years apart, the car itself was basically a time capsule...engine #1 blew up a few weeks after the test, and i had other irons in the fire so the car sat until engine #2 was ready to install. I was just picking up where i left off with regard to developing the car. To me the part that says it's because of the lighter rotating assy is because the closer the two engines got to steady state power production, the closer the power outputs were. By 3rd gear, there was only a 6 rpm/sec difference. Sorry, no 4th gear data available to compare from engine #1, that test area just isn't long enough.
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Old 03-03-2017, 03:47 AM   #225
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The real fact of the matter is that even a very light flywheel, after vehicle weight and all gearing is taken into account will make negligible difference in most cars.

The lighter the vehicle the more chance of a difference, likewise with the shorter the gearing.

And little of that applies to any of these cars as most gearing is still fairly tall and few are very light.
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Old 03-03-2017, 10:28 AM   #226
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Quote:
Originally Posted by North*power View Post
Haha I had a feeling you'd post something Good Hio. Car sounds amazing with the new exhaust! Being that you have probably the lightest clutch assembly, do you think the driver for the tach is accurate in keeping up with the actual rpm on freerev or lower gears? I've heard that the tach readout can't keep up sometimes. Did it take much for you to dial your idle back in after the clutch install?
I'd love to have your faceplated trans and clutch with a S1 sequential shifter and pressure sensitive shift ****. It would be as close to a full on Emco or similar.
Thanks

When your on it the tach us pretty far off till 3rd gear. In that vid it's back to idle before the tach is.

I did no actual idle tuning besides raising idle speed to 800rpm. Now what i did do to help with drivability was turn off the throttle cracker.

Quote:
Originally Posted by weedburner View Post
I had two engines that were pretty close to the same but different component weights. I didn't change the weight of the flywheel/clutch itself, but i did change the weight of the overall rotating assembly...

...Engine #1 was 4.04" x 3.48" w/ 5.7" i-beam rods, hypers with gas ported spacers and 1.2mm rings (12lb oil), 49lb crank balanced to a 1863g bobweight.

...Engine #2 is 4.03" x 3.48" w/ 6" aluminum rods, forged pistons with lateral gas ports and 1.5mm rings (14lb oil), 42lb crank balanced to a 1492g bobweight with pendulum style counterweights, drilled rod journals.

Both have flat tops with nearly identical quench and compression. Same intake and carb, same carb calibration. Exact same cam installed on the exact same intake centerline. Same flywheel and pressure plate installed in exactly the same car, same weight, with exactly the same gearing and tires. Even though these tests were a couple weeks shy of 2 years apart, both tests are on the same location with zero tire spin and conditions were very close to the same.

Here's the observed rates that the engines gained rpm WOT...

1st gear 2000 to 4000 rpm- engine #1 1634 rpm/sec........engine #2 1910 rpm/sec (276 rpm/sec difference)
1st gear 4000 to 6000 rpm- engine #1 1975 rpm/sec........engine #2 2217 rpm/sec (242 rpm/sec difference)
2nd gear 4000 to 6000 rpm- engine #1 1070 rpm/sec.......engine #2 1116 rpm/sec (46 rpm/sec difference)
3rd gear 4000 to 6000 rpm- engine #1 535 rpm/sec.........engine #2 541 rpm/sec (6 rpm/sec difference)

As you can see, in the higher gears where acceleration is slower there is not much difference in acceleration rate. But in the lower gears, the differences in rate of acceleration progressively increase.

There also seems to be a quite a difference in no load acceleration rate, but the conditions of the comparison were not the same. I had a clutch linkage experiment go bad in 2014 with engine #1, which resulted in a free-rev condition during a 4000 rpm WOT launch in which that engine gained rpm at an 8500 rpm/sec rate. I was also experimenting with pulling timing at the time for a no-prep race, but my records don't indicate that i was pulling timing on that particular launch.

Under NA free-rev conditions, engine #2 gains rpm at a 11,515 rpm/sec rate.

All acceleration tests are basically inertia dyno runs, even if that test is a no-load test where the only inertia resistance is supplied by the weight of the rotating assy itself. What most people lack is a way to collect accurate comparable data. Even though these tests were conducted almost 2 years apart, the car itself was basically a time capsule...engine #1 blew up a few weeks after the test, and i had other irons in the fire so the car sat until engine #2 was ready to install. I was just picking up where i left off with regard to developing the car. To me the part that says it's because of the lighter rotating assy is because the closer the two engines got to steady state power production, the closer the power outputs were. By 3rd gear, there was only a 6 rpm/sec difference. Sorry, no 4th gear data available to compare from engine #1, that test area just isn't long enough.

I noticed the same weedy. The biggest gains are in the first 2 gears because of less load on the motor. The clutch cannot change actual engine power but it can change the rate of acceleration of the engine. And last i check we don't race hp.....we race acceleration.

I think gm was trying to dumb down acceleration a bit in the first couple gears wuth these heavy *** clutch/fly set ups to help people maintain control of thr cars. Maybe some other reasons to but a heavy clutch/fly set up for sure hurts the 1/2 gear the most. We noticed in lazerlemons 5gen that the car just kinda seemed to accelerate the same in the first 2 gears no matter what we did. 3rd seemed to pull harder than 1st or 2nd because the motor was actually loaded. You could feel it better. We deemed it was because the motor was basically accelerating that heavy *** clutch/fly as fast as it could no matter what. Other vids of 5gens seem to confirm that.

If we can capture that momentum in the 1/2 gears it should help it. Of course I've ran this type of clutch for years now. Is it for everyone. ...no. but if you can make it work for its a decent mod for a ls. It really lets all the tq they make be felt.

Stevie is on point to. Although it seemed to make a difference in this 5gen. It's heavy and not geared as aggressive as it should be. His car is about 600lb heavier than mine.

Hammers car sounds so good!

Last edited by HioSSilver; 03-03-2017 at 10:34 AM.
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Old 03-03-2017, 11:04 AM   #227
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"Seemed to make a difference" isnt really a factual improvement though.

A louder exhaust can seem to many to make a difference because it sounds faster lol
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Old 03-03-2017, 02:33 PM   #228
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Well....if you didn't ignore weedy's factual information then you would know that it's not equivalent to louder exhaust. Keep in mind he is talking about a 7lb difference. I'm talking about a 40lb difference with a massive change in moi.

I was merely trying to point out that this is not some lightweight car with a ton of gear......lol :/
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Old 03-03-2017, 02:59 PM   #229
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Originally Posted by HioSSilver View Post
Well....if you didn't ignore weedy's factual information then you would know that it's not equivalent to louder exhaust. Keep in mind he is talking about a 7lb difference. I'm talking about a 40lb difference with a massive change in moi.

I was merely trying to point out that this is not some lightweight car with a ton of gear......lol :/
The numbers quoted in real terms are negligible. If they were repeated over a hundred tests or so, then maybe you could take them as meaningful, but they are still so small a difference...no odds either way.
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Old 03-03-2017, 04:17 PM   #230
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The numbers quoted in real terms are negligible. If they were repeated over a hundred tests or so, then maybe you could take them as meaningful, but they are still so small a difference...no odds either way.
1st gear 2-4k = 18.8% gain
1st gear 4-6k = 12.2% gain
2nd gear 4-6k = 4.2% gain
3rd gear 4-6k = 1.1% gain

These are gains in acceleration rate for the entire car on an actual road. Those engines might make around 500ft/lbs running steady state NA, making that 12.2% gain in 1st gear from 4-6k roughly equal to around 60hp.
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Old 03-05-2017, 04:15 PM   #231
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I call that a pretty good gain.
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Old 03-05-2017, 04:41 PM   #232
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Seems to make a difference to me
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