Putting a Caprice engine (L05-7) into a 92 g30 van (has L80e trans)

[AuroraGirl]

the reason for opposite threaded bolts or fan clutch is because a serpentine belt almost always spins the water pump with the backside of the belt (ive seen exceptions) and the backside of the belt means it would loosen in a normal threaded scenario. same with tensioners that the belts ride agianst on the backs, usually they thread reversed too

 

[L31MaxExpress]

the reason for opposite threaded bolts or fan clutch is because a serpentine belt almost always spins the water pump with the backside of the belt (ive seen exceptions) and the backside of the belt means it would loosen in a normal threaded scenario. same with tensioners that the belts ride agianst on the backs, usually they thread reversed too

Oddly enough, SBC fan clutches are standard thread and so are the idler and tensioner. On the GM fan rotation the fan drag actually tightens the fan clutch almost to a point the only way to get it off is an air hammer. I never even tight the clutches myself, the second the fan drag hits it, it is already tight enough that removing it is a fight. I have also had a SBC that the idler bearing locked up on and it twisted the bolt right out of the bracket and the idler feel off. I guess the GM engineers decided it was better to let it fall off, than lockup and do worse damage.

 

[AuroraGirl]

Oddly enough, SBC fan clutches are standard thread and so are the idler and tensioner. On the GM fan rotation the fan drag actually tightens the fan clutch almost to a point the only way to get it off is an air hammer. I have also had a SBC that the idler bearing locked up on and it twisted the bolt right out of the bracket and the idler feel off. I guess the GM engineers decided it was better to let it fall off, than lockup and do worse damage.

on my f150 with 300 inline 6 i had the idler pulley shear off the bracket it was bolted on. guessing the bearing was bad lol.. melted the center and twisted it off almost in a perfect circle,m such that the pulley "stayed" on but the belt just went flyong off. I put the belt back on because I didnt notice the damage right away

 

[L31MaxExpress]

on my f150 with 300 inline 6 i had the idler pulley shear off the bracket it was bolted on. guessing the bearing was bad lol.. melted the center and twisted it off almost in a perfect circle,m such that the pulley "stayed" on but the belt just went flyong off. I put the belt back on because I didnt notice the damage right away

That is the worse damage I am talking about. Breaking brackets, shearing off the mounting bolt and stuff like that. Better to just let the thing un-thread and fall off.

 

[AuroraGirl]

That is the worse damage I am talking about. Breaking brackets, shearing off the mounting bolt and stuff like that. Better to just let the thing un-thread and fall off.

especially when they use a large diameter center steel 8.8+ hardness bolt for retainign to a machined down cast aluminum bracket with a threaded hole. lol. thats easy recipe for snap

 

[Danboquist]

Going down the rabbit hole on stall speed for a converter, what I get so far.
I need to go deeper, for sure. Preliminary conclusion is that i need to keep the torque (specifically looking at the cam) down to a point where i can keep the torque converter under 3000.

1. Accurately deciding stall speed has a lot of factors: curb weight, cam, tire diameter, engine torque curve, drive ratio, etc.
2. Any torque converter >= 3000 will definitely require tuning.
(Seems like just about any changes work better with some tuning), Plus, the expense of the converters goes way up. I want to avoid these consequences as much as possible.
- It appears that this most directly can be attributed to the cam.
Still investigating.
I’d never heard of stall speed before, but here we are..

 

[Schurkey]

Stall speed is determined by engine torque applied to the converter. Torque is determined by both throttle position and RPM--if the throttle is mostly closed, torque will be low and therefore the stall speed is low.

So stall speed becomes a balance of the engine's power curve vs. the torque converter's ability to absorb that power at a given RPM.

Where this gets really interesting is the high-end torque converters (the ones that are made "right") in that they will flash fairly high at WFO, yet drive normally at low throttle.

The opposite of that is the crappy, budget-oriented "high stall" converters of the mass-market, which are just slushy everywhere.

 

[Danboquist]

Basically then it is based on the torque curve of the engine and the RPM.
It appears that a 92 OEM 350 for the van has something like 285 ft.lbs. Of torque and the stock converter on the 4l80e has a stall around 1800-2000 rpm.

This transmission guy on youtube uses a “K factor” equation to get in the ballpark for setup where you change the torque of an engine.
K=RPM/sqrt(torque) and
RPM=K*sqrt(torque)

So for a stock that would be (use 1900 as the RPM) and 285 for torque:
K=1900/sqrt(285) = 1900/16 = 119

Then if I jacked up the torque to say 350, the stall rpm would come out to:
RPM = 119 * sqrt(350) = 199 * 19 = 3781 RPM

I have no idea how I would use this, but it is interesting because it uses maths.

 

[L31MaxExpress]

Basically then it is based on the torque curve of the engine and the RPM.
It appears that a 92 OEM 350 for the van has something like 285 ft.lbs. Of torque and the stock converter on the 4l80e has a stall around 1800-2000 rpm.

This transmission guy on youtube uses a “K factor” equation to get in the ballpark for setup where you change the torque of an engine.
K=RPM/sqrt(torque) and
RPM=K*sqrt(torque)

So for a stock that would be (use 1900 as the RPM) and 285 for torque:
K=1900/sqrt(285) = 1900/16 = 119

Then if I jacked up the torque to say 350, the stall rpm would come out to:
RPM = 119 * sqrt(350) = 199 * 19 = 3781 RPM

I have no idea how I would use this, but it is interesting because it uses maths.

That math does not look even close to accurate. That kind of torque increase would stall it about 200 maybe 300 rpm higher, not nearly double.

 

[Danboquist]

That math does not look even close to accurate. That kind of torque increase would stall it about 200 maybe 300 rpm higher, not nearly double.

This better?
This is a good indicator that I won’t need to go crazy with a new torque converter. They get expensive. I need to figure out how to keep the torque within reason (probably via the camshaft) if possible.