[SnowDevil]

think I answered my own question, not finding an engine dyno in the area. guess Ill find out when I install it.

[gotgoat]

Just got back from Pontiac Heaven with the new combo 469 that I built. correction 1.5's on the exhaust and 1.6's intake on the rockers. I expected to run a 12.2 or 3 ran a 12.24 at 111mph. Shifting on the governer at 5200 and running a 28" tire. 1.9 short time. Will reset the trans shift point too 5800 and change the 323's to 373's. See what it does next year. (too bad were losing all our tracks out here in calif.) 600 miles to Arizona and back with the a/c averaged 12.9mpg with a 950hp "wow I'll take that"

Bill Baker

[Cliff R]

Bill, why such "low" expectations from the combination? I'd have expected running into the mid to high 11's over 115mph. Do you know the race weight?......Cliff

[harry k]

Originally Posted by blueghoast

LMAO

for ????

[gotgoat]

Originally Posted by Cliff R

Bill, why such "low" expectations from the combination? I'd have expected running into the mid to high 11's over 115mph. Do you know the race weight?......Cliff

Had the car weigh yesterday: 3760 w/ 9 galllons of fuel add 12 gallons for a full tank


4840 with a full tank with the pick up need to run with over a half tank.

update on my time slip I had a best short time of 1.81 averaged 1.84 most runs.

still shifting on the governor 5200 will set it up and a 355 gear. should lower the short time to a 1.72-4 hopefullly.

First time out with the new combo I'm satisfied. It will be in the 11's next year.

[harry k]

"4840" with a full tank with the pick up need to run with over a half tank

"3840" he meant .

[wheelspin]

Originally Posted by Cliff R

Bill, why such "low" expectations from the combination? I'd have expected running into the mid to high 11's over 115mph. Do you know the race weight?......Cliff

Cliff,
Bill and I were comparing time slips and car specs since this was his first outing with his new SD top end and cam. We have identical cams, heads, rocker ratios, intakes , and similar race-prepped Holley HP carbs. I'm zero-decked and Bill is .010 above. Bill runs a T400 trans and I have a 700R4; I run 9" wide 255 MT Street Drags and Bill runs 10" 275s. I think that he will be able to tune his combo into the 11s given a few changes. I believe that his race wt. is within 100# of mine which is 4180#. Strong head winds reduced my trap speeds to 113 from last years 115.4.

I am happy for Bill that changing his top end and cam took 1/2 a second out of his 4000#+ car on the very first outing . Bill is an ASE-certified mechanic and like me, a lifelong hot rodder.

[Steve C.]

Your Horsepower computed from your vehicle weight of 3840 pounds and MPH of 111.0 is 431.63.
http://www.wallaceracing.com/et-hp-mph.php



My previous 462 made 580.2 hp on our local engine dyno, first outing it ran 123.59 mph at 3750 race weight. The Wallace calculator using mph suggest my hp is 581.83.

Bur then this calculator suggests differant, it suggests 559.2 hp
http://www.dragtimes.com/horsepower-...calculator.php



.

[gotgoat]

Thanks for correcting my math Harry 3840 with a full tank

[Cliff R]

There is a LOT more in the combination.

Nearly identical engine as I'm using with a bit less compression. I use a bit less gear and a higher stall converter.

The last time I went out in good air the track was like wet grass, spinning to a "slow" 1.85 60', I went 11.64 @ 121mph. The air was around 800' on that outing.

At 3900' DA I've went 11.30's at 119-120mph with 1.61-1.62 60' times.

Race weight is 3740lbs, that's with the tank nearly full and me in it.

BTW, for most racing, I shift at 5000rpms. The car only slows about .04-.05 compared to shifting clear up at 5500-5600rpm's.

I would think high 11's for your combo would be relatively easy with a tad better traction. It should be running at least 114-115mph with that much power at the flywheel.

How much converter slip are you seeing?......Cliff

[gotgoat]

28" tire (et streets) 323 rear gear, 250 extra pounds (ME) Traction felt good no slip

well race weight with me in it and a full tank is 4090

Have a few changes to make, just to list two of them:
adjust governor to shift at 5800 (at 5200 now)install the 355 gear


converter slip... maybe Harry K can answer that Have the 10" Pontiac Special from continental

[Cliff R]

RPM's at the finish line should have been less than 4800rpm's. Those converters are very well coupled on the top end.

MPH is low for the combination of parts. Unless you were running into a 20-30mph head wind, there is a quite a bit of ET and MPH left on the table.

That car should easily run mid to high 11's over 115mph in full street trim, without a gear or shift point change....IMHO....Cliff

[harry k]

ok Mr. Cliff
according your auto math "RPM's at the finish line should have been less than 4800rpm's"
at 111mph he did, look at my dyno plot in the bottom 4870rpm but hes power @ 412rwhp oppose to 430+that he made,needs more lower gear ......

[Cliff R]

Harry, I'm not exactly sure what point you are trying to make? Most of our street combo's could use a little more gear, for optimum dragstrip performance. That's statement is pretty much a no-brainer. I'd leave the 3.23's in place, and continue to enjoy the vehicle on long runs with the GV's. About all that adding 3.55's will do is increase rpm's cruising. They will not have a big impact on ET or MPH.....IMHO.

If you want to test my theory, install a set of 26" DOT's and make some additional runs. The 26" tires will mimic the gear change to 3.55's.......Cliff

[harry k]

i am trying to point out there is no converter slip at 111mph that when he went thru traps at 4870 rpm as you stated rpm's should be close to 4800,
not a debate , hes not at his peak power when hes crossing the traps when you look the bottom plot eng rpm vs speed mph .

i agree with your theory of changing the tires to 26" tall, thats hes call, i think he will still change to 3.55 though retaining the 28" tall tires.

[Cliff R]

A few years ago I took three sets of tires to the track for back to back testing. I had a 24" tall set of full racing slicks, 28" Mickey Thompson DOT's, and a set of 9"-30" full race slicks.

We were at a local track on test and tune night, and got to make as many runs as we wanted to.

The difference is ET and MPH for all runs was barely measurable, the shorter tires just "buzzed" the engine harder on the top end of the track.

The effective gear change using 3.42 gears and tires from 24" tall to 30" tall is significant, and considerably more than a change from 3.23's to 3.55's. The big 455 engine just didn't care, it ran equally as well with any of the tires we tested that night.

Point here is, with a street driven car using an engine with a broad/flat torque curve, the expense of a gear change may not be worth it, considering about all that could result is buzzing the engine harder at speed on the highway, and on the top end of the track when racing.

We have quite a few of these engines in service, some in cars equally as heavy as Bill's, with similiar gearing and converter. Here are my observations based on the results we've obtained here with this engine combo.

The MPH is down considerably from where it should be, so there is some considerable improvements to be had without changing rear end gears. It should be running considerably quicker in 60'. I'd expect 1.70-1.75 60' time with that converter/gearing and good traction. A tenth right there will be apprx .25 tenths improvement in ET right to start with. Combine that with improving top end charge a bit, and the car will EASILY run into the 11's without a tire, gearing or converter change.....IMHO....Cliff

[Old Man Taylor]

The challenge we have out here is that most of the tracks that we run on aren't prepped well enough to get a really good 60' time. I have the same issue with my car. MPH is another story. I just ran a 10.04, and my best 60' was 1.44.

[Bruce Meyer]

Originally Posted by Cliff R

RPM's at the finish line should have been less than 4800rpm's. Those converters are very well coupled on the top end.

MPH is low for the combination of parts. Unless you were running into a 20-30mph head wind, there is a quite a bit of ET and MPH left on the table.

That car should easily run mid to high 11's over 115mph in full street trim, without a gear or shift point change....IMHO....Cliff

That car would be in the 11,s if he ran at your track. In phoenix its a different story due to altitude and there was a strong headwind at PH this year.
Example would be in 2003 when I won the division 7 campionship I had to slow my car down from low 12,s to 13.0 for the finals in Pomona. They have different rules for some reason.
In Phoenix I disconected the secondaries on my 850 Holey and it ran a 13.2. I figured I was good to go in Pomona. First run of practice I ran a 12.9. Not bad for 425 cfm.

[Old Man Taylor]

Bruce - You are right on. Since Pomona does not run "regular" races, we are pretty limited to getting on a good track. That's a classic problem comparing ET's in the southwest to other places. We had a guy visit us from back East for our Pontiac Drag Days races at Palmdale. He said he had run 10.13 back East. The best he could do at LACR was in the 10.80's. He didn't even stay for eliminations as his ego was too deflated.

B/T/W, sorry I missed you at the event. I saw your car in the car show, but I wasn't able to be around when you were there.

[Cliff R]

OK, if the track is totally at fault here, why would a gear change even be considered until runs were made at lower altitude, in better air, and with a tail wind?

The runs still look very slow in 60' and down in MPH for what I've seen from very similiar combo's, even in pretty crappy track conditions, near 100 percent humidity, and up near 100 degree outside temps.....IMHO.

Specifically on 60' times. In very good air with good traction my car will 60' around 1.61-1.62. In the very worst months when it's to hot all you want to do is go home and sit in the air conditioning and drink iced tea, it slows to 1.64-1.66.

Here's a run with the timing retarded, in really hot/humid air, shifting at 5000rpm's:

http://www.youtube.com/watch?v=6zVdo...uYW1txXWpCQ0s=

Nearly as I can remember, the 60' time on that run was 1.65 or 1.66. The only way I'd get it to slow to 1.75, or 1.80, would be to pull two plugs wires off of it and disconnect the secondaries!

Anyhow, not trying to be too critical of the OP's vehicle, I think it will run a LOT quicker when everything everything gets sorted out, including the crappy track deal......Cliff