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Discussion Starter #1
How will a high 1st gear affect 1/8 and 1/4 mile performance? Turbocharged, 600hp to the tire, 2.32 1st, 27" tire, 3.55 rear end gear. Car has a 2 step, hopefully can leave with some boost built up.
 

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Obviously every car is different....I have a 1.84 first gear, but with a 4.10 rear gear. Makes for a 5.94 final drive. You have a 2.32 with a 3.55 gear. Makes for a 5.87 final drive.
I have 26" tall rear tires, so my effective final drive is even steeper. I leave at 10 psi and ramp in the other 10 psi over the next 1.1 seconds. I usually get a 1.29-1.30 60 ft. Also I am dealing with quite a bit more HP.
Assuming your chassis is set up proper you should be able to make that gear work real well. Tire compound and track prep will be at play as well.
 

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Discussion Starter #3
Thanks. A few guys had me kinda worried that it would be a complete dog in 1st gear. My hope is that there is enough power to grunt it off the line, then be able to stay in 1st longer before having to shift.

I remember years ago having gone from 3.55 to s 4.10, the car jumped the line a bit harder, but 60 foots remained unchanged, I felt I was having to shift too soon with the 4.10. but then again, it was a different car, different transmission.
 

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I had a 3.73 rear gear for a while. That gave a 5.57 final drive. The only difference in the car in the 1/8 with the 4.10 was....nothing. The car reacted quicker, the reaction time dropped by almost a tenth, but the ET stayed the same.
 

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Discussion Starter #7
I think I'll just try the close ratio toploader and see how it goes. I've got zero in it, so I've got nothing to lose. If it doesn't work out, I can always throw a wide ratio gearset in it to get a 2.76. 1st.
 

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Makes me chuckle see you guys talking about “tall” first gears. I am engaged in 2nd gear as I am going by the 60’ marker. But as originally stated every car is different.
 

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Discussion Starter #11
I changed my mind. I ordered gears to make my toploader a wide ratio. This will give me a 2.76 1st gear. I can buy a replacement 1st gear and would have a 2.90.
 

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Stay away from the 2.90 1st gears. You may be able to change ratios by swapping out just 1 gear, but the gear geometry suffers. Because there's a change in pitch diameter without a change of center-to-center distance, the replacement gear will be weaker as it's teeth will be loaded much closer to their tip.

Grant
 

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Obviously every car is different....I have a 1.84 first gear, but with a 4.10 rear gear. Makes for a 5.94 final drive. You have a 2.32 with a 3.55 gear. Makes for a 5.87 final drive.
don't you multiply ... not add ?
 

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Pick one and use the converter.

As you make updates and start making more power, sometimes you find that the SLR getting higher than about 10:1 can COST you ET, especially on a small tire deal or on a marginally prepped track or in a car that doesn't leave well to begin with.

Lot of variables.

On a turbo car, sometimes you'll benefit from "loading" the engine a little more, which can be done a lot of ways. Converter. Final drive. Trans gearing. etc. Notice I stressed "converter". It's important. Or on a manual shift, the clutch. A serious setup is not using a King Cobra, but something that's adjustable, which might be tough to get dialed in on a turbocharged car.

A lot of guys have found great success with a powerglide, which is basically leaving in 2nd gear of most 3 speeds. In theory it shouldn't work. In reality it does. Point being sometimes we can benefit from trying different stuff.
 

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Pick one and use the converter.

As you make updates and start making more power, sometimes you find that the SLR getting higher than about 10:1 can COST you ET, especially on a small tire deal or on a marginally prepped track or in a car that doesn't leave well to begin with.

Lot of variables.

On a turbo car, sometimes you'll benefit from "loading" the engine a little more, which can be done a lot of ways. Converter. Final drive. Trans gearing. etc. Notice I stressed "converter". It's important. Or on a manual shift, the clutch. A serious setup is not using a King Cobra, but something that's adjustable, which might be tough to get dialed in on a turbocharged car.

A lot of guys have found great success with a powerglide, which is basically leaving in 2nd gear of most 3 speeds. In theory it shouldn't work. In reality it does. Point being sometimes we can benefit from trying different stuff.
yup! gotta see what the combo wants. going to something like a 1.58 first gear which worked great for us. wouldnt work for most people, but it allows us to manage the power better with that converter.

so many people over look how much ET can be found in the converter!
 

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Discussion Starter #16
I know very little about converters, I'm using an old toploader, first gear is a 2.32, I've aquired the wide ratio gearset so first gear is now a 2.76. I believe the 2.76 with a 3.55 rest gear should be a better combination.
 

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That's the downside to a manual. No converter. The converter converts torque; a fluid coupling. It also MULTIPLIES torque. It's not uncommon to see a 3:1 torque multiplication ratio, which means if you put 1,000 lb-ft into the converter, you can get up to 3,000 lb ft OUT of that converter. THAT is how an automatic can be faster than a manual, and is also why a powerglide-with 1.58-1.76-1.82-1.90 first gear ratio actually works. If you had a stick shift with a 1.76 first gear and dumped the clutch-even with an adjustable clutch-it wouldn't 60' as well as an auto would with the same low gear ratio. Where a stick shift shines is in a vehicle that has a really narrow power curve, in that the 3, 4, 5, 6 speeds are close enough in ratio to keep the engine in it's power curve. Auto's are catching up but still have a ways to go in that department. The new 10R80 is nearing manual shift territory in that respect.

The converter that some industrial equipment uses can have up to a 4.5:1 torque multiplication....they need it being that they're single speed. Our old fork lift that I had at the shop was like that. Automotive stuff is usually lower.
 

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That's the downside to a manual. No converter. The converter converts torque; a fluid coupling. It also MULTIPLIES torque. It's not uncommon to see a 3:1 torque multiplication ratio, which means if you put 1,000 lb-ft into the converter, you can get up to 3,000 lb ft OUT of that converter. THAT is how an automatic can be faster than a manual, and is also why a powerglide-with 1.58-1.76-1.82-1.90 first gear ratio actually works. If you had a stick shift with a 1.76 first gear and dumped the clutch-even with an adjustable clutch-it wouldn't 60' as well as an auto would with the same low gear ratio. Where a stick shift shines is in a vehicle that has a really narrow power curve, in that the 3, 4, 5, 6 speeds are close enough in ratio to keep the engine in it's power curve. Auto's are catching up but still have a ways to go in that department. The new 10R80 is nearing manual shift territory in that respect.
I feel a downside to an automatic is the converter and it's torque multiplication. That high multiplication factor only lasts for a few tenths of a second, but it dictates a less efficient overall setup for the remaining 98% of the run. The basic reason for dumping charge pressure on the hit is reducing the converter's initial multiplication factor.

so many people over look how much ET can be found in the converter!
Even more people overlook how much ET can be found in the clutch! IMO, swapping to an automatic is a step backward when you have the clutch figured out.
 

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Even more people overlook how much ET can be found in the clutch! IMO, swapping to an automatic is a step backward when you have the clutch figured out.
it would be interesting to see what someone REALLY good with a clutch could do with a radial tire VS what we do with the converters to leave the line...
 

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it would be interesting to see what someone REALLY good with a clutch could do with a radial tire VS what we do with the converters to leave the line...
It's actually easier to do radial with a clutch than it is with a converter, specifically because the clutch lacks the multiplication factor. The key with a clutch is controlling the inertia dump into the tire, you don't do that with a conventional adjustable clutch.
 
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