Shouldn't my car be quicker?

[LS1Formulation]

New update: After installing the 2 step, I've got my PB down to 12.20@111.28, with a 1.78 60'. I gained 19HP and 18TQ with the rod mod and dyno tune, but it's weird to me that my MPH has actually dropped over what I was running with a stock intake. I'm happier running quicker, MPH isn't the important thing - It's just odd.

[acammer]

Originally Posted by LS1Formulation

New update: After installing the 2 step, I've got my PB down to 12.20@111.28, with a 1.78 60'. I gained 19HP and 18TQ with the rod mod and dyno tune, but it's weird to me that my MPH has actually dropped over what I was running with a stock intake. I'm happier running quicker, MPH isn't the important thing - It's just odd.

What was the density altitude like? Changes in the air quality absolutely has enough influence to add/subtract a few mph/tenths.

[LS1Formulation]

It was about 2000 feet, so I know it has an effect, but it's consistently about 2 MPH slower than it was before the intake. Here's a vid of the run: https://youtu.be/1qnxrjiXu1E

[acammer]

Did you move your 3-4 shift point? I wonder if maybe you pulled 3rd deeper before, and perhaps that was helping MPH. Without data, it's gonna be a guessing game. It was fun watching the videos. Needs more clutch slip, if it'll take it! Those long gears are killing it for sure.

[Pkeen]

Get that bog out of it and It should be around 11.90's !

[LS1Formulation]

Nope, I've got my shift light set at 6850 for the 1-2, and then 6900 for the 2-3 and 3-4. By the time I react to the light, I'm hitting 7100 RPM pretty consistently. I know this because prior to my tune, my rev limiter was set at 7100 and I'd occasionally hit it. It's set to 7400 now, but I really want to try to stay away from that zone as much as possible. It definitely needs more clutch slip, but the window on this Spec 3 clutch is about 1" of pedal travel long, right at the top of the travel. It's pretty difficult to lift my foot all the way up to that sweet spot consistently.

I'll keep trying when I get her back from the bodyshop... Had a meeting with a guardrail in a freak downpour a week ago. Smacked the front fender, quarter panel, both wheels, the mirror, and a little of the front and a lot of the back bumper. I'd slowed down to 45 MPH but it was no use. Worn out Nitto drag radials are NOT rain friendly. There's a brand new pair on there now.

[acammer]

Originally Posted by LS1Formulation

Nope, I've got my shift light set at 6850 for the 1-2, and then 6900 for the 2-3 and 3-4. By the time I react to the light, I'm hitting 7100 RPM pretty consistently. I know this because prior to my tune, my rev limiter was set at 7100 and I'd occasionally hit it. It's set to 7400 now, but I really want to try to stay away from that zone as much as possible. It definitely needs more clutch slip, but the window on this Spec 3 clutch is about 1" of pedal travel long, right at the top of the travel. It's pretty difficult to lift my foot all the way up to that sweet spot consistently.

I'll keep trying when I get her back from the bodyshop... Had a meeting with a guardrail in a freak downpour a week ago. Smacked the front fender, quarter panel, both wheels, the mirror, and a little of the front and a lot of the back bumper. I'd slowed down to 45 MPH but it was no use. Worn out Nitto drag radials are NOT rain friendly. There's a brand new pair on there now.

Sorry to hear about the body damage - that's frustrating for sure. Little rain is no joke when you're in drag trim - I saw drops driving home Sunday while on the bias ply slicks/skinnies and I went right to full alert ready to back it down if it materialized. Fortunately, it didn't!

Sounds like the shift points should be pretty consistent. I'd start really tracking density altitude when you're making passes, as that will absolutely shift power around a bunch. Don't overlook windspeed and direction either. My local track is usually straight into a pretty good headwind, and that can alter MPH a good bit as well.

For the clutch, you gotta look at a clutch pedal stop. You'll thank me later. Basically, it limits the travel of the clutch to only what you need to make a good, full release. Which with an aftermarket clutch can be as little as HALF the actual pedal travel. The clutch stop helps remove the dead zone - so you are closer to engagement as soon as you start to move off the fully depressed position.

This is a very simple part that I run: https://afterdarkspeed.com/product/g...edal-stop-kit/

The other thing you really want to try to do is use the e-brake for some preload to stage the car. This will help tremendously with consistency and position you right on the edge of the friction zone as the tree drops. It also has the added benefit of helping to reduce breakage by reducing shock loads to the driveline. I have a how-to that might give you some things to think about if you're interested:

[LS1Formulation]

I watched your vids, definitely a help. I'll purchase that pedal stop and see how I like it. I'm going to do some math and see if I'm possibly revving out TOO far on my 2-3 and 3-4 shifts. I'm wondering if it's possible that I'm above torque peak after the shift. I'll try to get some things together while my ride is still at the body shop.

[LS1Formulation]

This is what I came up with:

*******************************
Final Gear Ratio : 3.91
Tire Size : 315-35-20
Max Power RPM : 6420
Limit RPM : 7100
*******************************

*********************
Gear Ratio Compound
*********************
1 3.010 11.769
2 2.070 8.094
3 1.430 5.591
4 1.000 3.910

***************************************
Gear MPH/1000 MPH @6420 MPH @7100
***************************************
1 7.25 47 51
2 10.55 68 75
3 15.27 98 108
4 21.83 140 155

*******************************************

Gear Change RPM drop (change @6420) RPM drop (change @7100)
************************************************** ***********
1->2 -2005 (To 4415) -2217 (To 4883)
2->3 -1985 (To 4435) -2195 (To 4905)
3->4 -1930 (To 4490) -2135 (To 4965)
************************************************** ***********

From what I'm seeing, I may very well want to lower my shifts. My power peak is at 6420, and my torque has kind of a double peak from 4600-5200. If I go by where it crests 400 lb. ft. ( peaks at 407 lb. ft. ), it's from about 4400-5600 RPM. That's a pretty wide torque plateau, and as it stands, I'm falling right into the center of it. However, with my gear ratios, when I shift from 3-4 @ 7100, my RPM drops to 4965. I'm trapping so slow for my ET ( anywhere from 108-112 ) that by the time I reach the stripe, I'm spinning roughly 5000 RPM or so. So 4th gear is almost useless, as I'm shifting to it around 100 feet before the end of the track, and barely gaining any RPM whatsoever. But if I lower my 3-4 shift to 6600, it will drop me right at the start of the torque plateau and I'll have a little more time under power... What do you think? Am I on the right track with my thinking here?

[acammer]

Originally Posted by LS1Formulation

This is what I came up with:

*******************************
Final Gear Ratio : 3.91
Tire Size : 315-35-20
Max Power RPM : 6420
Limit RPM : 7100
*******************************

*********************
Gear Ratio Compound
*********************
1 3.010 11.769
2 2.070 8.094
3 1.430 5.591
4 1.000 3.910

***************************************
Gear MPH/1000 MPH @6420 MPH @7100
***************************************
1 7.25 47 51
2 10.55 68 75
3 15.27 98 108
4 21.83 140 155

*******************************************

Gear Change RPM drop (change @6420) RPM drop (change @7100)
************************************************** ***********
1->2 -2005 (To 4415) -2217 (To 4883)
2->3 -1985 (To 4435) -2195 (To 4905)
3->4 -1930 (To 4490) -2135 (To 4965)
************************************************** ***********

From what I'm seeing, I may very well want to lower my shifts. My power peak is at 6420, and my torque has kind of a double peak from 4600-5200. If I go by where it crests 400 lb. ft. ( peaks at 407 lb. ft. ), it's from about 4400-5600 RPM. That's a pretty wide torque plateau, and as it stands, I'm falling right into the center of it. However, with my gear ratios, when I shift from 3-4 @ 7100, my RPM drops to 4965. I'm trapping so slow for my ET ( anywhere from 108-112 ) that by the time I reach the stripe, I'm spinning roughly 5000 RPM or so. So 4th gear is almost useless, as I'm shifting to it around 100 feet before the end of the track, and barely gaining any RPM whatsoever. But if I lower my 3-4 shift to 6600, it will drop me right at the start of the torque plateau and I'll have a little more time under power... What do you think? Am I on the right track with my thinking here?

I think you may be thinking this through wrong. First, forget about where peak torque happens - horsepower is the actual measurement of how much work an engine is capable of. What you want to do is maximize the average horsepower throughout the run. This means using a shift point after the power peak, but before or at where the power level past the peak matches the power at the shift recovery point in the next gear.

This post covers that really well: https://www.camaro5.com/forums/showp...72&postcount=6

I'll re-share it for those that don't wanna click the link:

I have a good visual to share on this to help you think about maximizing average power through each gear. This chart shows where you going to land with shift recovery on a 3-4 shift in a regular TR6060-M10 combo. Yellow is shifted at peak hp (6500rpm), green is shifted at about 700rpm beyond that, 7200rpm. It's not hard to see why shifting at peak power is leaving significant performance on the table, you're going to be buried on shift recovery much further down in the RPMs, where the car develops less power.

This is why I get so frustrated at dyno operators and tuners that run the car out to where-ever it peaks and then quit. That doesn't tell the whole story, and that 500-1000rpm beyond the peak is crucial for determining where the best shift point is gonna lay. Given the choice, I pull the car out as far as I trust the motor to routinely go - because that's your real potential operating range, and will help dictate what the best shift-point will be.

Another thing to keep in mind for this discussion is stick-shift vs. auto. Auto guys are faster for a lot of reasons, and shift recovery is one of them. The torque converter will reduce how far back down the rpms drop after a shift. This in turn means the car doesn't need to be pulled as far past the peak. Depending on what the curve looks like, you could very well shift 2-300rpm beyond the peak and not be giving up much. On the other hand, stick shift cars have zero slip once they make the gear change, and drop rpms much lower. So, they must be pulled MUCH deeper beyond the peak to make the best average power through the gear - like as shown in my graphic.

I hope that helps.

[acammer]

In your case, with stock gearing, you have the 3-4 shift occur in a TERRIBLE place, because just as you have found, it happens at like 1,000' into the run, just before you cross the finish line. That's not a great time to make a shift in general, because the aero load is highest there, and so the momentary disconnect in power for the shift really hurts acceleration. It also buries the RPMs. The 3-4 gap on the standard M10 TR6060 is awful, and that gear has the worst shift recovery of any other than the 5-6 which we don't care about. So again, you've got the aero loads at the highest, and now you're buried on power curve at like 5000rpm, well away from your best power.

The solution is gearing. 4.10s work very well in these cars because they move that shift back down the track, closer to the 1/8th mile mark. They also improve the starting line ratio, which makes the car easier to launch, requiring less clutch slip and helping keep the nose fully "up" through the entire 60'. Drawbacks are noise and reliability - the physical size of the ring gear doesn't change, so so the pinion must shrink in order to alter the ratio. This means a smaller pinion, with less teeth - which is less strength. Then you've got that in an aluminum housing, which WILL distort under hard enough loads - and if that gear mesh moves around even a little things will quickly tear apart. Now, put that in a heavy car with plenty of torque and traction, and you've got a recipe for broken parts. They will hold up for a while, especially if you avoid clutch dumps, wheel hop, and any other high shock-load activity, but the bottom line is that it's just a marginal rear end for the weight and power of the vehicle, and increasing that ratio increases the torque everything sees, which is good for acceleration, but bad for keeping things in 1 piece.

So, the real solution for a car you want to drag race regularly and not worry about, and you want to be geared PERFECTLY, is something like the 9" setup I have in my car. It's unfortunately very pricy - I bought mine used. It comes with a weight penalty too. Those costs were worth it to me, the car is now geared perfectly, and I just don't worry about the rear end any more.

The ZL1 3.73 rear end is another alternative to consider. The cost is substantially lower than a 9" setup - but they are getting harder to find, and costs are going up. It's also not an ideal ratio, but it is somewhat improved from the stock 3.45.

[LS1Formulation]

Another update: Found a problem I created due to inattentiveness, and it made a huge difference in ET. It also might mean I have to get my car retuned. I'll get to that in a moment.

Andrew, I already have 3.91 gears in my car - I thought I listed that, but I'm not sure. It definitely could use more gear. I'd love to have 4.56's but yeah, that's a huge expense. I don't know if I'd want to invest that into this car, or just buy a ZL1. I have everything done to my factory rear that I need to do. Detroit Truetrac, LPW cover, all poly bushings, BMR toe rods and trailing arms, and G-force axles. I no longer get any wheel hop, and I defininitely don't dump the clutch, so I'm pretty sure it will hold up for awhile. Not sure what the cut off point is on ET, however. Guess I'll find out!

Back to my findings... So yesterday, while prepping to go to the track, I realized I made a bonehead mistake when I installed my ported rod mod intake. I somehow overlooked the PCV line going into the intake behind the throttle body. So it's been sucking in unmetered air since the install. And I got it dyno tuned with it like that. I hooked it back up and instantly my car started idling lower, to the point where it's probably gotta get raised up. But that's not all. I went to the track and right off the rip, I knocked out an 11.98@115.30 with a 1.73 60' time. Holy crap, it felt SO much quicker, pulling way harder in the upper ranges. Never got another good 60' after that, but I ran 12.13@116.16, 12.15@116.01, and 12.14@115.62 with a 60 between 1.84 and 1.93, having to get out of the throttle to cut wheel spin each time. This is with a DA between 1500-1800 feet, similar to my previous best. Picking up 4-5 MPH just by fixing that vacuum leak is wild. But now I'm unsure if I need to get it retuned, because everything was done with this tube wide open. Any opinion on that?