[Steve C.]

We changed gears and were surprised at the results, results which might be of interest to some.
For years we have been running 4.30 gears, with the previous 462 motor that made peak power around 6400 rpm and most recently with the 450 motor that makes peak power at 6900 rpm. The 4.30 gears seemed to work out well, for example with the current 'loose' 8-inch converter and a 6800 rpm shift chip the shift light was coming on just before the traps. Best et to date with the 4.30's was 10.525 at 127.55 mph (foot brake/no nitrous/about 3650lb. race wt.) On that run the 60-ft was 1.539 and the weather was 78 degrees & 65 percent humidity.
We made the change to 3.73 gears in preparation for running a small amount of nitrous for the first time in the near future, but first we decided to see how the gears would effect the performance using the 'loose' converter (knowing that a tighter converter would need to go in when we try the nitrous). We thought the et's would fall off some with a small improvement in the mph... we'll surprise, the car ran faster! During time trials the car ran a 10.48 at 128.3 mph with a 1.52 60-foot, this with similar weather as before at 77 degrees & 63 percent humidity. During eliminations in the evening with slightly cooler air the car ran faster, a 10.459 with the brakes being applied before the traps... in an unsucessful effort not to breakout on our dial-in!
Lesson learned, the motor with its torque (581ft.lbs.@5400 rpm) likes to grunt thru the gears [img]/infopop/emoticons/icon_smile.gif[/img] As far as the mph not increasing, the converter is probably slipping on the big end more than before.
The big plus from all this, the car will be a little more street friendly with the 3.73 gears. I'm pleased.

[Steve C.]

We changed gears and were surprised at the results, results which might be of interest to some.
For years we have been running 4.30 gears, with the previous 462 motor that made peak power around 6400 rpm and most recently with the 450 motor that makes peak power at 6900 rpm. The 4.30 gears seemed to work out well, for example with the current 'loose' 8-inch converter and a 6800 rpm shift chip the shift light was coming on just before the traps. Best et to date with the 4.30's was 10.525 at 127.55 mph (foot brake/no nitrous/about 3650lb. race wt.) On that run the 60-ft was 1.539 and the weather was 78 degrees & 65 percent humidity.
We made the change to 3.73 gears in preparation for running a small amount of nitrous for the first time in the near future, but first we decided to see how the gears would effect the performance using the 'loose' converter (knowing that a tighter converter would need to go in when we try the nitrous). We thought the et's would fall off some with a small improvement in the mph... we'll surprise, the car ran faster! During time trials the car ran a 10.48 at 128.3 mph with a 1.52 60-foot, this with similar weather as before at 77 degrees & 63 percent humidity. During eliminations in the evening with slightly cooler air the car ran faster, a 10.459 with the brakes being applied before the traps... in an unsucessful effort not to breakout on our dial-in!
Lesson learned, the motor with its torque (581ft.lbs.@5400 rpm) likes to grunt thru the gears [img]/infopop/emoticons/icon_smile.gif[/img] As far as the mph not increasing, the converter is probably slipping on the big end more than before.
The big plus from all this, the car will be a little more street friendly with the 3.73 gears. I'm pleased.

[dammen8]

Just out of curiosity what did you cross the line at for the rpm? I am wondering if you went to a higher gear it would be harder to move the car so the convertor should slip more. I am just wondering if you noticed a difference at the end?

Chad Dammen

[Half-Inch Stud]

Steve,

Aside from this success in MPH and ET, seems your MPH is still low for your ET. Dumb question: Is there a chance that backing down the timing advance [1deg or 2 deg] may add some MPH?

Also, would a 10Inch converter ruin the combo?

H.I. Stud

[Steve C.]

The 4.30 gears seemed to favor the 462 motor that made its peak power at 6400 rpm. We used a 6200 shift chip, other shift points were tried but it didn't seem to make much difference so we left it there. With this motor we had a custom 10-inch converter that stalled around 4200. A very good short time with this combination was 1.49, happened twice but that was not the norm.
For the 450 motor that makes peak power at 6900 rpm we use a 6800 shift chip, again tried other shift points but that seems to work ok. We just left the same 4.30 gears in place but the 10-inch converter would not work, it was a real dog off the line. Inorder to get it to launch we had a custom 8-inch converter built that stalls around 5200. With this combination good short times are 1.5-1.52.
At 127 mph and 28" tires the 'formula' says 6600 rpm, but that's without converter slip. As mentioned with the 4.30 gears the shift light would come on well before the traps... probably zinging thru at 7000 or more rpm! Now with the 3.73 gears the shift light comes on just as you enter the traps. I wish I could report the exact rpm's for the trap speed, and the stall, but we don't have a play back tachometer.
We never mess with the timing. On the dyno 35.5 to 36 worked best so we just keep it there with a crank trigger. I'll bring up the subject at the shop with John.
I inquired as to a tighter converter with the 3.73 gears but the general concensus is that it would hurt the launch. We will see because when we try the nitrous later on we will need to put in a tighter converter, we can try it on the motor and see. It would be nice if it worked since a tighter converter would be better on the street.
FWIW I have a 4-series carrier in the rear end and 3.73 is the only choice with it, otherwise it's 4.10 and up. Thus the choice.

[Half-Inch Stud]

sounds like backing down the Total ADV from 36/35.5 to 34 may bear fruit on MPH.

I don't know how the launch [chasis shock] and 60foot would be affected. not my bag.

[SLOW 77]

I told my dad how fast you went last night, he was [img]/infopop/emoticons/icon_smile.gif[/img]. Very nice times! Nice to see it was done with a set of 3.73's in it, with a tighter convertor and the bottle you will be running in the 9's.

[johnta1]

Steve, what was the 1/8th mile et and mph?

------------------
johnta1
Pontiac Power RULES !!!
www.wallaceracing.com

[Steve C.]

With 4.30 gears:
60-ft 1.539
330-ft 4.336
1/8et 6.723
1/8mph 102.6
1/4et 10.525
1/4mph 127.55
With 3.73 gears:
60-ft 1.521
330-ft 4.319
1/8et 6.7031
1/8mph 103.06
1/4et 10.486
1/4mph 128.31
And
60-ft 1.523
330-ft 4.307
1/8et 6.681
1/8mph 103.21
1/4et 10.459
1/4mph 128.20
(note: brakes applied before traps this run)
More runs were made but I don't have the time slips here at the house. When I took the car to Norwalk in Aug with the 4.30 gears we had some 1.50 to 1.51 60-ft times but with the higher altitude the car was running 10.60 at 127 mph. The weather was very similar on all the runs shown and the car had the same tune-up each time. Nothing was changed except the gears.

[johnta1]

Nice runs!

Half Inch stated that he thought the MPH was low compared to the ET.
I thought it looked the other way around.
Compared to my Bird,the 60' and ET were slow compared to the mph at least in the 1/8th.
I think you could pick up a lot of ET and possibly 60' with some chassis tuning.
You had traction bars didn't it?

My car would run the 1/8th in 6.80's at about 101 mph.Kept playing with the ladder bars and rear shocks,and front shocks until it got to 6.40's and 1.39 60's,with nothing else done to it.

I also had my best ET's short shifting to 2nd.As soon as the wheels came up,bam,shifted.If I tried it at higher RPM's,like 6000 or so,it fell off.Didn't feel bad,just didn't run the fast number.
I had to manually shift it.(air shifter)



------------------
johnta1
Pontiac Power RULES !!!
www.wallaceracing.com

[Goatman]

Seems to me that his MPH and ET are a little slow for the 60', but within margin. Probably has too much converter slippage before. Seems to have gotten better with the 3.73's. Will pick up a bunch with a tighter converter.

[Half-Inch Stud]

I'm a rookie at this, but have data within the signature.

I think the MPH appears low, since I had 3MPH less for 1/2 second more.

johnta1, yea, short-shifting to second also helped my ET, from 11.3 to 11.1/11.0. MPH was most always there.

Overall, I'm a believer in dual carbs for good MPH.

------------------
"11.00/123MPH/1.50 60foot/29.5"/4.10:1/10"/472 #48/Flat HYD/DualQuad/Wenzler/3250Lbs
12.00/112MPH/1.61 60foot/26"/3.31:1/10"/472 #48/FlatHYD/Q-Jet/Torker/3650Lbs"

[PONTIAC DUDE]

Taking gear out really works, But loosens up the convertor. I have gone from 4.10's, then 3.90's and now 3.50's and the converter balloons to 4500 on motor and 5800 on spray, then would just keep slipping in high gear.
Sent it back and had it tightened up. Seems to really work now.
Here ya go. Went to Ga on Fri, but came home with a ring blowby problem on Nitrous, but seemed OK on motor last pass. Didn't want to chance it thought and if I stayed. you know what would have happened. The Dude just watch????.
10.59 @ 126.95 on motor. 9.8-1 compression(87cc's with the piston .020 in the hole) and a 3.50 gear with a 29.5 BFG Drag radial. 1.54 60 ft'er. estimated 3550 lbs with driver. Shifting at 6200 and thru the traps at 6000.
9.68 @ 143.42 on spray leaving in 2nd gear (Dolp,,,didn't pull it all the way back into low!!!!), but had excessive crankcase pressure blowing pure oil out the breather I have installed where the valley PCV valve was. Time to re-ring after 35 400hp nitrous passes(75 total). Damn those moly rings and low tension oil rings. LOL.
I wonder if I go to 3.23's......Hahahahahaha.

------------------
Injection is Nice, but I'd rather have 'GAS'....Nitrous that is.
http://www.angelfire.com/fl4/pontiacdude428

[Half-Inch Stud]

.68 FOM for Pontiac-Dude on all motor.
That's very nice.

[David Holmberg]

Hey DUDE, I have a set of 2.41's in the garage... [img]/infopop/emoticons/icon_wink.gif[/img] 2nd gear is all you will need... [img]/infopop/emoticons/icon_biggrin.gif[/img]

[Torment]

Dude, them tall gears kinda murder on the rings huh? Specially leaving in second gear [img]/infopop/emoticons/icon_redface.gif[/img] Hope it don't start a trend for ya.