gearing and 1/8 mile times

I have a 3200# door car wanna be pro mod, 526 hemi,bruno lenco 2 speed with a 1.68 first gear, 4.10 rear gear, 33.5 hoosier co7 tires. This is my first year out and have been learning the hard expensive way so far.
1st question. we have run alot of 4.45 to 4.48@168 so far on a very mild tune up @3200#. what could I expect to gain if I take out about 400# over the winter? all steel car,roll up windows and all the glass, so it should be possible. You think I could get 2 tenths out of it. I know #100 is a tenth in the quarter on average, so maybe .5 in the 1/8???
2nd question. Do you think I have a gear problem, or could use a high speed lean out because on the shift I drop and loose any where from 700 to 1000 rpm on the computer. after the shift at about 8100 to 8200 the car will barely recover in rpms, usually trap around 7500 to 7600 rpm. should I try to run a 4.56 rear, or try a 1.80ish first gear, or both to try and tighten up the drop in RPM. No room for a 3 speed, and I am on a severe $$$$ budget so any tips to get the hooptie a little faster is greatly appreciated. thanks howard

 

my 2cents

I dont want to sound mean, but you have the wrong combination for a heavy car. what body is it? what wheel base? strange you dont have room for a 3speed. heavy cars could use the gears. If you want to be a real promod then sell the roller and get a real one. again not trying to be mean, just real.

 

You need the 1.80 and the 4.56 gear if not even a 4.71. That will help alot. What engine is it that you are shifting that low?

 

1/8th to 1/4 mi conversions

We did several articles in the IHRA DRM tech page about 1/8th to 1/4 mi conversions. You can download those for free from:
www.racecarbook.com
Click on ARTICLES
bob szabo
racecar book author
ps. we are moving. We'll keep revised contact info on that web site.

 

MARK 6052 dont hold back, tell me what you mean.no offense, I know i need a true pro mod, but money just want alow it. but I am definatly having fun trying and actually have qualify many times. the car is a all steel 68 camaro, stock wheel base, and with my big ass and double frame rails, stock wheel base just not enough room for a second transmission section on the lenco, done tryed.
BLOWNAWAY. its a 526 tfx, aj headed hemi with a 14.71 hh littllefield retro at only40%. I am sure I can raise the shift rpm, but trying to save valve springs and parts. this is my first hemi so learning right now. Plus I am leaving from a idle foot braking it due to rearend being weak till I can get a floater rear end this winter. Then we will leave on the trans brake.
BOB s thanks for the link, got some reading to do.

 

Gears

Howard, You need to run more gear. With a 2 speed trans you get a lot of rpm drop at gear change as you already know. Going to a 1.80 will make it worse and compound the problem. I would go to as much as a 4.86 and even think about going as low as 1.40 on first gear. This will give you almost exactly the same overall 1st gear ratio, but less rpm drop at the shift which will keep the boost up and the motor in the happy range. It will probably help your back half times as well.

Think of it this way- 4.10 x 1.68 = 6.888 which drops to 4.10 at gear change
4.86 x 1.41 =6.85 which drops to 4.86 at gear change.

 

Danny, thanks for the tips.I have a 4.56 to try now, so I will give it a try, and will start looking for a 1.40ish first gear to try in the tranny to. Heck, I have a set of 10.5 tires that I am going to try at our next local race to see if the old hooptie can handle it.

 

Dont defeat the purpose of putting a lower rear gear by putting in a longer first gear in the tranny. By doing this you will only gain gear ratio in high gear.

 

It sounded like what he was needing to do was close the rpm gap up on the gear change, going to a taller 1st gear and shorter rear gear should do that. Seems like you can get away with a taller 1st on a big inch convertor deal, even with a heavy car.