increasing stall speed and rpm after shifting

[jbaker]

hey all,
this is more of a general question , rather than looking for exact numbers.

im contemplating increasing the stall on my vigilante 9 1/2". lets say im at
3400 rated stall now. lets also say im going to increase rated stall to approx.
5000. will this change in stall speed, let the motor recover at a higher rpm,
after shifting into each gear. this assumes i am NOT locking the converter.

i would assume that a higher stall speed will slip the motor to a higher rpm
after each shift, but ???????????????????? im not sure

thanks

 

[A. G. Olphart]

As a guess, you may have the theory right, but it will take a good rotating assembly and better valve springs to survive a cam whose torque curve runs from 5 grand up.

 

[WE4]

Like the above said

You better have one HELLUVA motor!!!!!!!
With even a 3400 stall you must have one HUGE turbo!
I would be very interested in what you have and where you are going.

Bruce
WE4
www.PTSXTREME.com

 

[jbaker]

tranny is behind a 413 chevy smallblock.
with a torque peak at 4900 rpm

trying to understand if a higher stall, actually
lets the motor recover at a higher rpm
after each gear ratio change. once again,
i am not locking the converter.
just trying to get a grasp on this aspect only
and if what im talking about, is referred to
as "shift extension".

i realize there is a multitude of points to be covered
here, but just want to get a feel if the motor will be
closer to the engines torque peak after each shift
due to the converter stall being higher

thanks and sorry about the chevy smallblock

 

[WE4]

No sorry...

Legitimet question. I think the answer you are looking for is "no". I would be very careful as to how I convertered this car.

Bruce
We4
www.PTSXTREME.com

 

[jbaker]

thanks for your input bruce.....................

 

[A. G. Olphart]

OK, Bruce... I'll bite. Why not?

According to Peter Ogden's neat 'Gear Calc' Program, a 200R4 shifting 1-2 at 7500 RPM will drop 3203 RPM to 4297. Since this is below the specified stall, why won't the engine see stall speed? 2-3 only drops to 4777 which I'd think might be hard to tell from a 5000 RPM stall, and if the shift RPM is raised to 8500, evsn 1-2 only drops to 4870.

Guess I can see 'why not' if one assumes that an engine with a 5000 torque peak will always be shifted above 8000 or so.

Sure glad I'm not buying the parts... a lot of RPM for that size motor.

 

[jbaker]

very interesting A.G.
we are shifting at 7000, and "no more" due to valve train budget. otherwise
all 4340, je pistons, dart little m, etc.

its interesting what you say about shift point rpm and where the motor drops back to versus rated stall. considering a 7000 rpm shift, then the motor
would drop back to 4010 rpm on the 1-2 shift....... needless to say this is all theoretical, but is food for thought. with that said, what is to hold the motor from revving up to
the 5000 rated stall from the dropback rpm of 4010 ????? is this referred to as "shift extension" ??????????????????

now............ none of this assumed slipping up to rated stall, will
happen if the converter is locked, which i do not do. this theory thinking, has me thinking i could restall to 4800-5000 and effectively get closer to my max. torque point after the shift. my rated stall is currently 3400 rpm. so if we look at my current situation shifting at 7000.... the math says the motor drops back to 4010 on the 1-2 shift. which is 610 higher than 3400 stall, which says the converter has no reason to slip any higher. that would mean im
not getting my max torque after the shift.


sooooooooooo..............so much for the blah blah blah,
thanks so far everyone and lets see if we can get to the bottom of this.

now what we need is for someone to ring in that has actually examined
this "theory" at the track, and can help us understand, what in fact is actually
going on.

jerome

 

[WE4]

We talked yesterday..

Right?

Bruce
We4
www.PTSXTREME.com

 

[jbaker]

yes we did bruce, and thanks for your time and insight about the rotary "heat pump"


hehehehehe
jerome