What gear ratio for boost?

jakes84k10 · 10-07-2019, 01:45 PM

Me and one of my best buddies are turbo ls swapping his 76 c10. Combo will be a sbe 5.3, vsracing billet 7875, 4l80e with an hd2. He currently has a factory 12 bolt rear thats been recently rebuilt and had 3.73s installed. will be ran on a messily 5lbs or so until he gets used to power(going to be both of ours first 400+ whp vehcile), and then tuned up to a max of around 15 or so hoping to make around 600 to the tire. Hows the 3.73s going to act? will be a strict street truck and maybe see the local track a couple times a year.

Topfun99 · 10-08-2019, 02:00 PM

Quote:

Originally Posted by jakes84k10

Me and one of my best buddies are turbo ls swapping his 76 c10. Combo will be a sbe 5.3, vsracing billet 7875, 4l80e with an hd2. He currently has a factory 12 bolt rear thats been recently rebuilt and had 3.73s installed. will be ran on a messily 5lbs or so until he gets used to power(going to be both of ours first 400+ whp vehcile), and then tuned up to a max of around 15 or so hoping to make around 600 to the tire. Hows the 3.73s going to act? will be a strict street truck and maybe see the local track a couple times a year.

How much rpm and how tall a tire? At lower boost levels he might be able to get away with the 3.73 gears. I run a 3.50 with 30" tires and go thru the traps right at 7000 rpm - 168 mph.

jakes84k10 · 10-08-2019, 03:49 PM

Quote:

Originally Posted by Topfun99

How much rpm and how tall a tire? At lower boost levels he might be able to get away with the 3.73 gears. I run a 3.50 with 30" tires and go thru the traps right at 7000 rpm - 168 mph.

rev limiter will be set around 7000-7200 as its a stock bottom end with arp2000 bolts. itll be a 30inch radial. will start with about 5-8lbs(somewhere in the 475hp range) and then our "high" boost ill be around 15 or 16 making around 600, or atleast thats the goal. were limited to pump 93 here.

Topfun99 · 10-09-2019, 01:58 AM

Quote:

Originally Posted by jakes84k10

rev limiter will be set around 7000-7200 as its a stock bottom end with arp2000 bolts. itll be a 30inch radial. will start with about 5-8lbs(somewhere in the 475hp range) and then our "high" boost ill be around 15 or 16 making around 600, or atleast thats the goal. were limited to pump 93 here.

You won't run out of RPM unless you have such a lightweight car that it goes over 160mph.

Bad Medicine Racing · 10-31-2019, 07:37 AM

A 4500lb truck with 30" tire will probably need at least a 3.73. I would leave it in there a go with it.

Briansshop · 11-03-2019, 10:23 AM

Quote:

Originally Posted by Bad Medicine Racing

A 4500lb truck with 30" tire will probably need at least a 3.73. I would leave it in there a go with it.

Agreed. Mine is 4280lbs with me in it,30" tire,3.73s.

10-07-2019, 01:45 PM	#1
jakes84k10 Junior Member Pre-Staged Join Date: Nov 2017 Location: Mount Holly, NC Posts: 98	What gear ratio for boost? Me and one of my best buddies are turbo ls swapping his 76 c10. Combo will be a sbe 5.3, vsracing billet 7875, 4l80e with an hd2. He currently has a factory 12 bolt rear thats been recently rebuilt and had 3.73s installed. will be ran on a messily 5lbs or so until he gets used to power(going to be both of ours first 400+ whp vehcile), and then tuned up to a max of around 15 or so hoping to make around 600 to the tire. Hows the 3.73s going to act? will be a strict street truck and maybe see the local track a couple times a year. __________________ Stock 07 Mustang GT auto/vert - daily driven 84 Chevy k10, built 700r4, 383 stroker, 1 3/4 headers, dual 3in exhaust(soon), work in progress 93 Wrangler, 4.0, 5 in lift, 33s, 8.8 swap, 4.10s, locked front and rear

10-31-2019, 07:37 AM	#5
Bad Medicine Racing Member Pullin gears Join Date: Dec 2009 Location: Alabama Posts: 599	Re: What gear ratio for boost? A 4500lb truck with 30" tire will probably need at least a 3.73. I would leave it in there a go with it. __________________ 5 second 3700lb G body, stock long block 4.8 with a LJMS cam and some boost.

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