14 replies to this topic

[mariner]

Lots and lots of pure power here 

 

https://www.enginela...400-horsepower/

 

 

Very wisely I think nobody stands near the car when its under load !

 

 

What is interesting  is how much the nose of the casr rises despite a very strong looking hld down strap under the nose .

[gruntguru]

Not that long ago, top fuel was making similar power - with nitro - and replacing rods and pistons after every pass. That motor did 8 pulls in a day with no maintenance.

 

I just watched the whole video. You can see the turbo blanket on the driver's side being pulled toward the compressor inlet. Needs to be better secured of course but - it suggests pretty extreme air velocity to the side of the inlet - I would be trying a small bellmouth on the turbo inlet.

[Slumberer]

“This thing is making 5,400 [horsepower] to the hubs — I guarantee you this thing is making 6,000-plus horses to the crankshaft,”

 

That seems an awful lot of drivetrain losses, or am I missing something?

[Greg Locock]

Diffs are horribly inefficient. But try and find any measured numbers on that and I'll bet you are out of luck. 85% is the usual guess, it isn't far wrong. Around town they are worse.

[gruntguru]

So 0.15 x 6000 = 900 hp

 

Need a very big radiator for that diff.

[GreenMachine]

Are those sorts of drivetrain losses linear with power output?  Revs?

[Greg Locock]

Complex, to say the least. There's very little published literature on it which is odd since the instrumentation -driveshaft torque strain gages and wireless transmitter-is commercially available

 

https://metromatics....a torque sensor.

[Greg Locock]

Quick literature survey

 

https://www.geartech...es/0786x/Yu.pdf

 

There is an SAE paper but it didn't pop up

[GreenMachine]

Thanks Greg!

[gruntguru]

[Greg Locock]

NFW, for hypoids

[404KF2]

Worm on my 1966 404C! 4.25:1

[MatsNorway]

How does one make a hypoid overlap with the Helical Bevel? And why does the graph start at 0?

 

Hypoid i new was bad. But I am assuming they run Helical in a drag car.

 

But don't you get a little bit of extra ratio possible with hypoid? You sort of do the worm gear thing. More sliding less pushing.

 

1:1 worm made me curious, is this graph from a theoretical/mathematical paper?

 

Here is a sketch i found on a possible 1:1 worm. I struggle to see the engagement after a full rotation. It seems a 1 : 1 worm would function/look differently than the normal worm gear.

 

https://i.sstatic.net/o4tU7.jpg

 

 

Is Manolis? still around? he could pull of a model better i guess. Autodesk Inventor does not allow me to go below 1 : 6 on worm gear.

 

Tried to make a screw with a 1:1 ratio on the coil and a counterpiece. I managed to constrain them and it moves to a point. But a full rotation is beyond my modelling capabilites. At least with only a few minutes of fiddling.

 

Even with 1:1 on each coil sweep it looks to be not 1:1 Ratio.

Edited by MatsNorway, 14 February 2025 - 10:44.

[Greg Locock]

grunguru's graph ignores the huge effect of stiction and other low speed friction effects. Crucially it also assumes constant mesh engagement, whereas a real hypoid diff is only correctly meshed at one torque. That's why when you set the pinion clearance it is a compromise. If you set it to be perfect at 50% torque then at full torque the losses go through the roof, and if you haven't got it perfect at a sustained power (eg towing up a hill) then again the oil cooks.

Edited by Greg Locock, 14 February 2025 - 22:52.

[gruntguru]

Yeah, I did find it on an industrial gearing site where gearboxes often find themselves in constant torque applications.