these numbers dont seem to compute. Keep in mind that these are rear wheel numbers and we weren't comfortable reving the motor past 5,500 rpm so we actually stopped at 5,300 and it was still making power. what is confusing me is, how could my torque be so much lower then the famously advertised 510 ft lbs? is it hopefully because this is through the drive train? 407 HP peaked @ 5,300 rpm 405 ft lbs torque peaked @ 4,800 rpm
There is reason to believe that factory had a finger on the scale when they rated the max torque on the 455. JW has never tested a stock 455 that made as much as 510 ft lbs. This could also be accounted for based on a dyno calibration difference.
What kind of loss should you expect on HP and Torque to the wheels? I believe 15-20% loss of hp through the drivetrain is normal. I have never heard the factor for torque loss.
Jim, There was a musclecar magazine that did a complete stock rebuild on a 455 Stage1 motor, and they did get to 510 ft lbs of torque, and something like 380 HP. They had to use about 38* of timing though. Wish I could find that magazine.
I think Jw's conclusion is also based on his interview with the chief engineer at the time , Cliff Studaker.
I think I read on here once Jims normal number he reads was 470 ft lbs on 70 existing builds hes dynod ...if your at 405 ftlb * 1.20 (for 20%) driveline losses your crank torque would be ~ 486 ftlbs and ~ 488hp - no slouch ! J
Just curious as I'll be throwing mine on a chassis dyno soon: what are the specs of your motor build? Thanks, Jon
I poked around on the net a little and it seems 20% loss of horsepower is on the high side, probably closer to 16% or 17%. Im not sure if that factor applies to torque as well. Does anyone know for certain?
i'll do my best , i'll work from the top down. 1) 1050 cfm proform (4150 holley style) carb 2) TA SP1 intake very mild gasket match porting 3) TA 1.6 roller rockers 4) TA stage 2 SE heads with Gessler level 2 porting 5) stage 2 headders with 3' exhaust out 6) TA's "The Gibson" cam 7) JE 11:1 pistons .030 over stock crank, rods
Those chassis dynos are all over the place relative to one another. So I would not try too many conclusions about chassis dyno numbers except to see if a change improves output that day.
Hey Dan, your build is pretty close to mine. What did you say you ran at the track in the 1/4 mile? Also what gears and converter?
steve, our combination's arent that close, you have the TE heads with a better port job (i think), a bigger cam, and now 1.65 roller rocker, making your cam even bigger, i think that the total weight of the car with driver and a half a tank of gas is 3,250. 373 gears in a chevy 10 bolt 8.5. the converter stalls at 3200 rpm and by the dyno numbers dosent seem to lock up until about 4,200 rpm (thats what the dyno tech told me, not sure what that means). if thats the case, seems to me like im making power a little too late in my power band.
Wow! your car is way lighter than mine, I think Im sitting at about 3800lbs. Your 10 bolt is more efficient than my ford 9" as well. Here is an et calculator that I input info from your previous ET...... I think I remember you saying you ran a 11.7 in the past. It comes very close to the RWHP number that you saw on the chassis dyno. <FORM><CENTER><TABLE cellSpacing=0 cellPadding=0 width=520 border=3><TBODY><TR><TD align=left bgColor=#c0c0c0 colSpan=2><CENTER>Estimated 1/4 Mile Horse Power Calculator</CENTER></TD></TR><TR><TD align=middle bgColor=#a8c7a7><CENTER><TABLE cellSpacing=0 cellPadding=3 width="100%" border=0><TBODY><TR><TD>1/4 Mile ET: <INPUT size=10 value=11.70 name=qtret> </TD><TD>[SIZE=+0]1/4 Mile MPH: [/SIZE]<INPUT size=10 name=qtrmph> </TD></TR><TR><TD>Vehicle Weight: <INPUT size=10 value=3250 name=wgt> </TD><TD>[SIZE=+0]60' ET: [/SIZE]<INPUT size=10 name=sxtyet> </TD></TR></TBODY></TABLE></CENTER></TD></TR><TR><TD align=middle bgColor=#a8c7a7><CENTER><TABLE cellSpacing=0 cellPadding=3 width="100%" border=0><TBODY><TR><TD>[SIZE=+0]RWHP from ET: [/SIZE]<INPUT size=10 value=401.06 name=rwhpet> </TD><TD>[SIZE=+0]Break HP from ET: [/SIZE]<INPUT size=10 value=481.272 name=brkhpet> </TD></TR><TR><TD>[SIZE=+0]RWHP from MPH: [/SIZE]<INPUT size=10 value=0 name=rwhpmph> </TD><TD>[SIZE=+0]Break HP from MPH: [/SIZE]<INPUT size=10 value=0 name=brkhpmph> </TD></TR><TR><TD>[SIZE=+0]Max G's Acceleration:[/SIZE]<INPUT size=10 value=Infinity name=sxtyg> </TD><TD>Hook Factor: <INPUT size=10 value=0 name=hook> </TD></TR></TBODY></TABLE></CENTER></TD></TR></TBODY></TABLE></CENTER><CENTER><INPUT onclick=HPcalc(this.form) type=button value=Calculate name=compute> <INPUT onclick=clear(this.form) type=reset value=Reset> <INPUT onclick='window.open("HPCalc-help.htm","Help","toolbar=no,location=no,directories=no,status=no,menubar=no,scrollbars=yes,resizable=yes,width=450,height=450")' type=button value=" ? " name=help></FORM>[SIZE=-2]Copy write 1999 by Kenneth R. Zink II (S-Series.Org)[/SIZE] </CENTER>
Wow. With that build, those numbers seem pretty low. I am planning on dyno'ing mine soon and have been doing some reading. I know that chassis dynos can vary a lot, but how much? Jon P.S. ( I'm gonna start a new thread to see what I can expect at the rear wheels based on my build. I think I've been getting a little over zealous.)
whammo. unfortunatly, i ran a 11.9, but that was before my head work and cam change, and that was with the 850 carb, not the 1050. if that calculator is right i will be prety upset that i spent about 2,500 between porting heads and cam/carb upgrades (almost 3,500 if you include the TA front timing chain cover) for .2 tenths.
Dan, what is your target ET? Did they do any tuning on the chassis dyno? To take advantage of your engine combo you may need to fine tune timing and mixture as well and possible gearing or converter set up?