Carbureted LSX forum - stall speeds
05-08-2012, 11:30 PM
hey guys i wasnt going to originally but now i think ive convinced myself i need a new converter. the truck is an 89 sierra regula cab stepside z71. the truck right now has 4.88 gears with 32" tall tires. the motor is a 03 lq9 with a dual plane intake and a holley 750dp. there is no cam yet or i can not say for sure if i will cam it down the road. i have been doing some research and think 3000 is a good stall but alot of the guys are saying atleast on the FI motors to run a 3600 since these motors like to rev. and once the truck is done it will be sitting on a set of 35" tires and i think that with a 3000 stall and above that with these gears it will just want to spin all over the place more then hook. any recomendations on stall speeds would be greatly appreciated
05-09-2012, 07:10 AM
With vehicle weight and the assumption that the tires are wide, I have no idea how that would act. But trucks I see usually don't spin on pavement too bad.
05-09-2012, 10:15 AM
the tires are going to be a 12.5 wide. as to the whole truck theory not spinning i can not say. when the truck had the slightly moded 350 tbi (aka no balls)with the 3.73 and 35s by matting it they would break loose. so now with the lq9 and 4.88s i can't see it being much better. or would something along the lines of a 2800 stall be better? i have been trying to find a dyno graph of a stock lq9 with a carb conversion to see where it starts making power but i cant find one anywhere
05-09-2012, 01:17 PM
Ok, just hit me, the pinion angle you have can cause tire spin and lifter trucks usually have funny angles, the smaller the converter the better in that case as torque and power comes in later than the old TBI motors that had instant TQ and no HP, if that gives and insight.
A stock converter would be great, now when you do want power, a 2800 would be better for allowing you to get/be in the torque band more instantly, or the foot of it rather, causing faster acceleration of the tires, i think a 2000 stocker with 4.88s would do well.
05-09-2012, 01:35 PM
Normally im the first one to advocate a higher stall converter, but in this case I have to agree with Zone. Lifted trucks have jacked up pinion angles, so all a stall is going to do is break the tires loose quicker, and im willing to bet, induce massive axel hop with the lift. JMHO. Eric L
05-09-2012, 05:31 PM
In my old 74 Blazer with a 400ci SBC (gen1) with about 400HP, 6" lift, 4.56's, 38's, and a 3000 stall...I could torch the tires at will off the line...worked great in the mud (cleared tires well), and could lay the hurt on more than a few.
I feel the stall and gears are a bit much (but depends on the trucks use). I would go with 4.56's max but no less than 4.11's and about a 2000-2500 stall....again, depends on the trucks use.
05-09-2012, 11:43 PM
well the truck is going to be an all around rig. will be doing some lilght to moderate towing 1000lbs to the ocasional 5000 once a year when i pull the boat. i cant lie ive spent way to much on this thing to take it thorugh the mud so it will mostly be a pavement princess. obviously its not going to be a daily driver or for gas mileage. that what my other vehicle or bike is for. but i do want it to have lots of power and be able to spank the ocasional rice burner when you pull up beside them. nothing like saying their little 3000pound car got beat my a lifted truck. as to the 4.88s i cant really go back on those are they are already in the truck front and rear. im starting to think maybe a 2500 stall with lock up capabilities. now where is a good place to get a converter from and who should i stay away from?
05-10-2012, 12:12 AM
The pinion angle doesnt always have to be jacked up if the axle has a shim kit. The stiff lift springs will make it spin easier and it it has lift blocks, please get rid of them. They cause axle wrap and then shit will break.
05-10-2012, 09:54 AM
i dont plan on running the lift blocks. either i will have new springs made. or have mine re arched a friend had his re arched and they worked great. the truck will either have traction bars or ladder bars to get rid of the twisting and hop if there is any.
05-10-2012, 04:50 PM
Your motor and mine seem exactly the same! There are at least 3 - 4 articles I've found with the LQ9 4 barrel setup and dyno #s. PM me if you need 'em.