AOD+3.73+125 MPH TRAPS SPEED= RPM?

eda50

eda50

Club Member
My 89 coupe has thr above setup with an injected 302 and as S trim with a 2.98 pulley making 13-15 lbs. (I think the gauge is off) I have ported edelbrock heads, cobra Lidio cam, lidio chip, (old school from like 96) 36 lb injectors, 255 in tank, t-rex inline, msd 6al btm, and the timing set at 25 degrees. I was running at Milan this past weekend at the track rental, and popped a head gasket at the top of the track. I have my shiftlight set at 6,000 and it was on for awhile before I crossed the finish line. I didn't look at the tach to see where the revs were when it blew, but I'm understandably curious. I know that 3rd gear is 1:1 like a c4. Looks like it's going to have to be race gas and a rev limiting pill in the future, question is where to limit the revs. Any other suggestions would be great. Thanks,
 
You didn't pop a head gasket!

You obliterated it!!! Jason sent that converter back to precision after he bought the car and it still didn't come up to where it was suppose to be (4200) .


Mike.
 
eda50, its basic math

tire height times pie divided by 12=x
5280(feet in a mile) divided by x=y
y times gear raito = rpm @ 60
rpm@60 times 125 divided by 60= your rpm @ 125 in 3rd
automatic should only loose 4-6%

hope that helps.
 
What about a 3.55?

Het first off, thanks guys. Great info. You both make being stupid much easier for me.

Well, I shift at 6,000 on the street, unless the race is real close, then I might leave the light on for another 100 revs or so. That calculation with a 3.73's and 24" tires puts me at 6791!!! On a stock block. I have no idea how much boost I was making, but it'll make 15lbs (on that possibly innaccurate gauge) at like 5800. No wonder it popped that thing with stock fuel lines eh? What do you think would happen with a 3.55? Or, should I just put a 6,200 pill in my MSD and let it go through on the limiter? I think that would kill my mph though. What would you do i it were your car that's cheap?
 
Are you sure you are running a 24" tire? Factory tire height is just short of 26" that would change your numbers some.
 
Tire size

Yeah, I measured it last night. It is a 245-50-16 Nitto 555r. It is exactly 24" tall. And I stand corrected. The calculator says 6900 rpm. Either way, looks like even a 26" brings the revs WAY down. Like 500 rpm, is that right?? Wow.
 
if your converter is a fluid coupling, and not like a stock aod converter which is a direct drive, with 5% slippage in your converter, your mph calculations would be 132mph times .95=125.4 with a 24" tall tire your rpm would have to be 6899 or 6900 rpm to go 125mph.
change the tire to a 26" tall tire, same calucations, it would take 6371 rpms
 
Tire size

Wow. That is great. I'm so glad that I don't have to switch gears just to race now! Ignorance is NOT bliss! Thanks for all the help. Mike, is my converter a fluid coupling?

Mike, I never got to talk to you about that trans you built. On the street, it is like a cvt. Smooth as a hookers ass. (after she waxes it of course!) When you're in the pedal? Second gears is an ANIMAL!!!!! It feels like it's gonna break the seatback. I really don't remember what 3rd felt like. I was really just zoning at that point. Ask Scott with the yellow Nova what 2nd gear feels like! So far very well done!!
 
26 inch tire X2.

I have a similar setup but run a (3.73) c4 and a 28 inch tire and I am going through the traps at 133 mph around 6300

My other notch has a C4 and a 26" tire with a 4:10 and a little blower and I go though at 6900 @ 125! Gotta have the gear to make the boost though..
 
eda50 said:
Yeah, I measured it last night. It is a 245-50-16 Nitto 555r. It is exactly 24" tall. And I stand corrected. The calculator says 6900 rpm. Either way, looks like even a 26" brings the revs WAY down. Like 500 rpm, is that right?? Wow.
Click to expand...

The 245/50/16 is a 25.6" tire which is classified as a 26" believe it or not. What you need as a 28" tire.
 
It's a

eda50 said:
Wow. That is great. I'm so glad that I don't have to switch gears just to race now! Ignorance is NOT bliss! Thanks for all the help. Mike, is my converter a fluid coupling?

Mike, I never got to talk to you about that trans you built. On the street, it is like a cvt. Smooth as a hookers ass. (after she waxes it of course!) When you're in the pedal? Second gears is an ANIMAL!!!!! It feels like it's gonna break the seatback. I really don't remember what 3rd felt like. I was really just zoning at that point. Ask Scott with the yellow Nova what 2nd gear feels like! So far very well done!!
Click to expand...


Single shaft AOD which makes it a NON-Lockup torque converter. Scott has my stuff too. His back is probably hurting when your trans shifts :bowrofl:.

Give me a call later today 586-255-3426.

Mike.
 
You must log in or register to reply here.
Back
Top