N00b question... How fast could this spin...and work?

[eliteweapons]

I have a chevy 350 that shifts at 9500 but that is a very expensive bottom end.

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[betterthanyou]

Keep in mind a Small Block has a longer stroke. That plays a HUGE part in RPM developement.

A short 2.8L stroke will reduce piston speed quite drasticaly and allow for much more RPM with a component of comparable strength.

So your very expensive bottom end can spin at 9500 with a 3.48" stroke. If the same expense (maybe even less) was invested in a 2.8L 2.99" crank then another 500 RPM could easily be had.

I still agree with everyone that a venture like this will cost a good chunk of change.

But the original question asked if it could be done and would it work

My answer is YES!

[Ortie666]

i say givver, but umm, id make sure its ballenced and u spent some change on it, i lost one my 85 2.8L roadracing it was aproching 9-5Gs it was pretty much stock besides a mean ignition

[sharkey]

a good example of this would be top alsohol funny car. most guys were shifting at 9500rpm max a couple years ago. then in order to get the breakage down, the rules changed and dropped the blower overdrive, and it knocked the cars down a good 2 tenths. to combat this, racers changed everything in the car, gearing, clutches, even chaged to a short stroke big borew motor, all so they could rev it to 10,500rpm to get the blower boost back were it used to be.

No man we fucking never run our engine that high. Not even close. If we hit the rev limiter at about 9500 then we toss all the springs. Under 8500 RPM is our operating range.

we shifted at 9500, went through the top end about 9700. the top guys now shift at 10,500rpm to run 5.50s in a funny car. they have gone from the traditional 4.310 bore/4.5" stroke to a 4.5" bore/4.300 stroke to get the higher rpm. more rpm, spins the blower faster, gets more boost, makes more power. lower budget teams dont attempt this. 3 runs on a set of steel valve springs, 8 runs on a set of titanium springs before they are junk. this rpm eats parts, but it makes ya go fast.

with an alcohol dragster, to run a 5.40 they are shifting at 10,500rpm with a 452" motor. to run 5.30, shifting at 11,000rpm.

[RacerX11]

This 10K rpm engine will be useless until someone finds a transmisison that can handle an input shaft speed that high and actually work. Wasn't Curtis having problems with his Getrag shifting any higher than 8000? The RWD guys have more options, but not cheap.

Marty

[The_Raven]

This 10K rpm engine will be useless until someone finds a transmisison that can handle an input shaft speed that high and actually work. Wasn't Curtis having problems with his Getrag shifting any higher than 8000? The RWD guys have more options, but not cheap.

Marty

Good point, but not much of a concern when you're bulding a 10K RPM plus engine, usually a tranny isn't much of a concern, meaning that it's part of the package.

[v6h.o.]

This 10K rpm engine will be useless until someone finds a transmisison that can handle an input shaft speed that high and actually work. Wasn't Curtis having problems with his Getrag shifting any higher than 8000? The RWD guys have more options, but not cheap.

Marty

Yes, The trans wouldn't shift properly past 6800-7200 rpm range and up.
I've felt it myself.. And this was with 2 different transmissions, He just blew up trans #2 just a few weeks ago racing the car.... Sigh. I was behind his car in the staging lanes (racing Steve's turbo wagon for him) and watched it do a small hop.... then nothing.

For the 3t40 style transmissions, you cannot spin them any faster than 6500rpm IIRC due to the pump's not being able to handle that type of speed.
The rest of the GM FWD auto's I'm not sure what the limiting rpm is now on them either.

[betterthanyou]

I wonder if Curtis is having a problem with the syncros simply frying themselves from the high RPM. Syncros of a different material and a different fluid viscosity may be of some help.

If bearings are going then a piece of more precice construction and a different fluid viscosity may be needed.

[The_Raven]

I'm just glad I know my tranny can built to run speeds that high, or I'll just switch to one that does.

[v6h.o.]

I wonder if Curtis is having a problem with the syncros simply frying themselves from the high RPM. Syncros of a different material and a different fluid viscosity may be of some help.

If bearings are going then a piece of more precice construction and a different fluid viscosity may be needed.

I think its more of an issue with the Speed at which the trans is spinning, The centrifical forces on the synchro/synchro slider and dog's are not what the stock tran's was intended to spin at and shift.

Also think the case is twisting and warping under such loads which is why its so hard to shift in the lower gear due to the torque, IF the case is flexing under the load would explain the hard shift feel as it doesn't take much to cause a shift rail to bind.

$$ could fix his issues, And these problems can be sorted out, But he's not interested and say's he's just going to street drive the car from now on I guess.