So i have a lq4 with a vic jr intake and a holley 3310 750 vac sec. I have a th400 and way to tall in my opinion 2.29 gears. I have 22" wheels. My question to u guys is it feels like it doesn't hav the power i expected could this be from the combination of heavy wheels crappy gears and the hp robbing th400 or is it something else i noticed it runs better with the curve #2 in the msd
Carbed lq4
- Thread starter NorthWestRider
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The taller the tire, the higher the effective final drive ratio. With a 2.29 rear gear and 22" wheels it is insanely high geared. What is your tire size?
Here is a good tire height calculator I like to use:
http://www.wallaceracing.com/tire-aspect-calc.php
Then I plug the tire height into this rpm calculator:
http://www.csgnetwork.com/multirpmcalc.html
Use the bottom (third) section of that page that includes an option for the transmission final gear ratio (1:1 for you since it isn't an overdrive).
I like to shoot for about 2600 RPM at 85 mph on the highway. That's with an overdrive. Obviously you don't have an overdrive. Do you drive your car on the freeway much?
I took a blind stab at it and assumed a 29" tall tire and put 3.08 for the rear axle ratio and came up with 3,033 rpm at 85 mph. That's revving a bit much for me but it is 85. You want to balance around town performance (lower gear feels better) with highway cruise rpm (lower gear makes engine rev higher). With that tall of a tire I would at least want a 3.08 but it really depends on where and how you drive your car. If you don't get on the freeway at all then I would put an even lower gear in it like 3.73 or 4.10.
Here is a good tire height calculator I like to use:
http://www.wallaceracing.com/tire-aspect-calc.php
Then I plug the tire height into this rpm calculator:
http://www.csgnetwork.com/multirpmcalc.html
Use the bottom (third) section of that page that includes an option for the transmission final gear ratio (1:1 for you since it isn't an overdrive).
I like to shoot for about 2600 RPM at 85 mph on the highway. That's with an overdrive. Obviously you don't have an overdrive. Do you drive your car on the freeway much?
I took a blind stab at it and assumed a 29" tall tire and put 3.08 for the rear axle ratio and came up with 3,033 rpm at 85 mph. That's revving a bit much for me but it is 85. You want to balance around town performance (lower gear feels better) with highway cruise rpm (lower gear makes engine rev higher). With that tall of a tire I would at least want a 3.08 but it really depends on where and how you drive your car. If you don't get on the freeway at all then I would put an even lower gear in it like 3.73 or 4.10.
My rear tire is a 265/30/22 wich is 28.28 tall i dont do a whole lot of freeway drive n but occasionally i do but i dont do 85 usully round 60-70
Honestly my speedo on the car dont work for some reason wont go past 35 but not to worried bout it right now i use a speedo app off my phone
I have rear end i can build but at the same time its just still a 7.5 was hope n to get a good deal on a factory posi till i could find something a lil stronger
If you aren't drag racing the 7.5 will be fine. 3.73 will feel great around town but won't be fun on the highway with no overdrive. 3.08 is probably a decent compromise. If it was me I would go with an overdrive and 3.73 or 4.10.
3.73 and call it a day, I had 24s with 4.10s and a th400 and it was just fine on the highway. ... as long as I stayed under 75. I also had 26s with a 4l60e and 3.73s and it felt stock at cruising speed but woke the truck up off the line.
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