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Raced the car today, and running slow??

Posted By: 451Mopar

Raced the car today, and running slow?? - 04/10/11 07:11 AM

Took the Charger out today, and having problems getting ET out of the car, also bad 60' times.
The Basics: 1971 Charger street car, Scaled today at 4,090 pounds race weight (car and driver.)
Racing a Bandimere (Morrison Colorado) my altemeter was showing 6,800 ft altitude.
My best run was the first run, they got worse after this one:
60' = 1.868
330 = 5.033
1/8 = 7.664 @ 93.51 MPH
1000 = 9.943
1/4 = 11.866 @ 117.83 MPH.
This run I was short shifting at 6,200 RPM?

My 60' times were usually 1.90's and about 12 flat ET's?

My tires are MT Street Radials, but they are about 7-8 years old and almost worn out. They din't seem to be as sticky as when they were new?
Also, I'm not sure how to launch the car with the new 5,000 stall converter. This new converter seems to leave softer than my old 3,500 stall converter? Or maybe my transition to WOT is going lean? Maybe I need more accelerator pump shot?

Anyhow, looks like I have some tuning to do to get this thing running right.

Any ideas where to start?
Posted By: Randy..

Re: Raced the car today, and running slow?? - 04/10/11 07:24 AM

et looks pretty good, 60ft a little off BUT thats a lot of weight, how much gear? lot of stall for that big of a car.
Posted By: 451Mopar

Re: Raced the car today, and running slow?? - 04/10/11 07:44 AM

The rear is 8-3/4" with a 741 case 3.91:1 gear sure grip that I think may have come out of a truck?
The tires are the 10.5"x27". That was my best ET, aftwards most were right at 12.00?
One of the cars I raced (a claped out race car with lexan windows, etc), ran the same MPH, but with much better ET and 60' times.

Anyhow, when i chassis dynoed this car, it was making 100+ more HP than the old engine which would run 12.50 @ 110 MPH, I figured the extra power and torque would get me closer to 11.50 and 120 MPH?
Posted By: joedust451

Re: Raced the car today, and running slow?? - 04/10/11 07:54 AM

Quote:

Took the Charger out today, and having problems getting ET out of the car, also bad 60' times.
The Basics: 1971 Charger street car, Scaled today at 4,090 pounds race weight (car and driver.)
Racing a Bandimere (Morrison Colorado) my altemeter was showing 6,800 ft altitude.
My best run was the first run, they got worse after this one:
60' = 1.868
330 = 5.033
1/8 = 7.664 @ 93.51 MPH
1000 = 9.943
1/4 = 11.866 @ 117.83 MPH.
This run I was short shifting at 6,200 RPM?

My 60' times were usually 1.90's and about 12 flat ET's?

My tires are MT Street Radials, but they are about 7-8 years old and almost worn out. They din't seem to be as sticky as when they were new?
Also, I'm not sure how to launch the car with the new 5,000 stall converter. This new converter seems to leave softer than my old 3,500 stall converter? Or maybe my transition to WOT is going lean? Maybe I need more accelerator pump shot?

Anyhow, looks like I have some tuning to do to get this thing running right.

Any ideas where to start?



1st. thing i'll say, at that Alt. & weight your doing fine with an 11.8, If you ran at a track with DA around 2000-2200ft. & knocked off a good 800 lbs. that combo would be 1 second faster or better, thats a solid 10.8 right there, You need to match the converter to the engines torgue curve, meaning if your max torgue comes in at 4300, you should select a "flash" stall about 3-400 above that if memory serves me, so your looking at around a 4600 stall, you may have over done it, The quality of the converter is also very important, that'll make or break the ET & MPH.

I myself think your doing quit well with what your up against (weight & high Alt.)
Posted By: joedust451

Re: Raced the car today, and running slow?? - 04/10/11 07:56 AM

Quote:

The rear is 8-3/4" with a 741 case 3.91:1 gear sure grip that I think may have come out of a truck?
The tires are the 10.5"x27". That was my best ET, aftwards most were right at 12.00?
One of the cars I raced (a claped out race car with lexan windows, etc), ran the same MPH, but with much better ET and 60' times.

Anyhow, when i chassis dynoed this car, it was making 100+ more HP than the old engine which would run 12.50 @ 110 MPH, I figured the extra power and torque would get me closer to 11.50 and 120 MPH?



Not at that weight & Alt., be happy with the .7 & 7 MPH you got.
Posted By: MR_P_BODY

Re: Raced the car today, and running slow?? - 04/10/11 02:28 PM

Your problem is just traction... old worn out tires
sure wont help the cause.... a 11.8 run should have
a 111 mph and you have a 118(almost) which should be
11.2..... thats on a racing set up
Posted By: sam64

Re: Raced the car today, and running slow?? - 04/10/11 03:57 PM

i know this wont help,but going from oklahoma to bandimere made my 10.90 car an 11.40 car.you'll get it lined out,new tires will do wonders.
Posted By: 451Mopar

Re: Raced the car today, and running slow?? - 04/10/11 04:33 PM

Thanks for the replies.
I am going to have to get new tires soon anyhow, and I think that may help? If anyone is running the MT street radials, how much pressure do you run? I had 22psi in the tires.
On my last run I dropped the pressure to 20 psi, did a good burnout and launched at a higher RPM, which helped get the 60' times back around 1.85, and got the tires to move about 1/4" on the rims.

The torque converter is an ultimate 9", and I like it. It is really tight on street driving, and dosen't flare up to the stall speed unless I hammer the throttle, but the stall speed may be too high for my combination. I have more tuning and testing to do before making changes to the converter.

My uncorrected Power when I chassis dynoed the car a few months back (on a good wether day) was 469 HP @ 6,100 RPM, and the power pretty much was flat to 6,600 RPM before power started to drop?
Air/Furl was pretty constant at 12.26-12.33:1
Posted By: 451Mopar

Re: Raced the car today, and running slow?? - 04/10/11 04:39 PM

Forgot, Peak torque is 423 ft/lbs around 5,300 RPM?
Posted By: Von

Re: Raced the car today, and running slow?? - 04/10/11 05:27 PM

IMO, converter is fine.

I run 15 PSI in my street radials. IMO, ETs are pretty touchy to air pressure. 7 year old tires are your biggest problem.....

Your MPH shows bottom 11s when hooked....
Posted By: 451Mopar

Re: Raced the car today, and running slow?? - 04/10/11 08:55 PM

One issue I need to check on is my cam button and oil pump drive gear. I didn't reinforce the timing cover and I think there is some clearance between the cover and cam button? I have a hard time getting a good timing mark reading when adjusting the distrubitor, it looks like the timing is jummping around? Dang it, It just occured to me that could be because I hooked the magnetic trigger right near the distrubitor cap, and may be getting false triggers from the other wires
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