ET Prediction vs Consistency
#700778
05/17/10 06:38 PM
05/17/10 06:38 PM
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Joined: Jan 2009
Posts: 52 Bakersfield, CA
MarkKirby
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Ok so here's the problem......well to some it's not considered a problem.
This weekend I made 9 passes with the ET never varying more than .006 the entire day. A dream day from the standpoint of consistency, which is not unusual for this combo. Everybody says I should not complain and be thankful the car is so freakin consistent. R/Ts were all .00X-.01X so it was a good day by going to the money window as well.
So what's the problem????? The problem is....the weather varied about 1000' feet during the day. This car should have slowed down at least 2-3 hundredths(if properly tuned).....but it didn't. Carb builder says I'm way lean but LM-1 disagrees at 12.5-13.0. Engine builder says quit whining and keep winning. I still think something is wrong. Any ideas?
416 SB at 13.5:1 Holley 950HP Jetted at 84/86 No PV....Idle a little on the rich side perhaps 575hp @6500...550tq @4700 Protrans 904 A-1 8" converter @5500....launch at 4600 5.13 Dana 3300lb loaded A-Body, 4-link Overtired at 16 x 33 x 15 GY ET 10.649 to 10.657 at 124.74(every pass same mph) DA between 2150 and 3172
What do you think????
Mark & Nancy Kirby
1971 Plymouth Duster
The Grape Ape
10.20 @129mph 1.32 60'
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Re: ET Prediction vs Consistency
[Re: MarkKirby]
#700779
05/17/10 06:47 PM
05/17/10 06:47 PM
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Joined: Nov 2009
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dennismopar73
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top fuel
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well yes id say something wrong dont think you have given enough info because if i was building small blocks and car that weighs as much as youres i want to rebuild it exactly as youres and lose some wieght get her down 2800 maybe put a 1050 dom on it
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Re: ET Prediction vs Consistency
[Re: MarkKirby]
#700780
05/17/10 06:53 PM
05/17/10 06:53 PM
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Joined: Jun 2003
Posts: 52,972 Romeo MI
MR_P_BODY
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When a engine is lean they do stay very consistent so it could be the A/F ratio reading is wrong... to close to the end of the collector can cause this...I dont like it lean and just move the dial to compensate... JMO
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Post deleted by Defbob
[Re: MR_P_BODY]
#700781
05/17/10 08:01 PM
05/17/10 08:01 PM
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Anonymous
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Anonymous
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Re: ET Prediction vs Consistency
#700782
05/17/10 08:10 PM
05/17/10 08:10 PM
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Joined: Jan 2009
Posts: 52 Bakersfield, CA
MarkKirby
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I never shut down in the lights. Can't get to neutral and I think this is too hard on tranny. I quit using this test years ago.
The plugs look a little fat to me with tan porcelain and a couple threads darkened on the body of the plug.
Mark & Nancy Kirby
1971 Plymouth Duster
The Grape Ape
10.20 @129mph 1.32 60'
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Re: ET Prediction vs Consistency
[Re: Brian Hafliger]
#700784
05/17/10 08:23 PM
05/17/10 08:23 PM
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Joined: Jan 2003
Posts: 5,488 SoCal
Brian Hafliger
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Another thing I noticed Mark is your MPH...I ran 126-127mph and only had 560HP with 3350lbs. Either the dyno HP is not matching the e.t. or there is a problem with the car. What kind of 60ft. does it normally do?
Brian Hafliger
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Re: ET Prediction vs Consistency
[Re: MarkKirby]
#700787
05/18/10 11:44 AM
05/18/10 11:44 AM
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Joined: Dec 2008
Posts: 184 Central Coast
Plumcrazyracing
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Central Coast
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Quote:
Ok so here's the problem......well to some it's not considered a problem.
This weekend I made 9 passes with the ET never varying more than .006 the entire day. A dream day from the standpoint of consistency, which is not unusual for this combo. Everybody says I should not complain and be thankful the car is so freakin consistent. R/Ts were all .00X-.01X so it was a good day by going to the money window as well.
So what's the problem????? The problem is....the weather varied about 1000' feet during the day. This car should have slowed down at least 2-3 hundredths(if properly tuned).....but it didn't. Carb builder says I'm way lean but LM-1 disagrees at 12.5-13.0. Engine builder says quit whining and keep winning. I still think something is wrong. Any ideas?
416 SB at 13.5:1 Holley 950HP Jetted at 84/86 No PV....Idle a little on the rich side perhaps 575hp @6500...550tq @4700 Protrans 904 A-1 8" converter @5500....launch at 4600 5.13 Dana 3300lb loaded A-Body, 4-link Overtired at 16 x 33 x 15 GY ET 10.649 to 10.657 at 124.74(every pass same mph) DA between 2150 and 3172
What do you think????
Kirby, was this past weekend the first time out with the new combination?
If you ran this combination previously, how did the E.T. compare to previous DA's and track conditions.
What type of weather station? Has it been calibrated?
As far as weather, if the DA went up did you guys end up with a decent tail wind? (Notorious at famoso)
Last but not least, did your 60' drop off (and then pick back up on the top end) at all or was it consistent as well?
Steve
Oh yeah, Dave has a nice valve body with a clean neutral.
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Re: ET Prediction vs Consistency
[Re: Plumcrazyracing]
#700788
05/18/10 02:59 PM
05/18/10 02:59 PM
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Joined: Jan 2009
Posts: 52 Bakersfield, CA
MarkKirby
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Wow! A lot of good thoughts here. Thanks for the help.
Brian
Yes it's the same cam. You have mentioned before that you think I can pickup with a cam change. What cam in particular are you thinking of. I currently have .627/.637 with 276/281 @50 in at 106. And yes, I installed the Super Victor which did not gain anything over the previous Offy Port O Sonic I have run for 20 years. Not one single HP! The Dominator is an interesting idea and one which I might try if I can find an adapter somewhere. I might just go ahead and jet the thing way up to see what happens. It's just that with an aggressive racing schedule we have so precious few TNT opportunities to woodshed these things. The MPH discrepancy is probably due to the big gear and tire(5.13 and 16x33). And yes, the 60' times also do not vary with weather.
Cab
I am prepared for the car slowing down and loss of consistency. I would trade consistency for predictability any day. No problems with idle it's clean and steady at about 1000rpm in gear.
340B5
No real urge to go any faster....just looking for predictability in the face of constantly changing weather conditions.
Steve
Where the heck have you been? I've been looking for you the last couple of races. This is not a new problem for me. Ever since I stopped predicting ET by the seat of my pants and started using sophisticated weather equipment the car has not followed the rules. I use an Alta Lab and Crew Chief Pro that are both good pieces and regularly calibrated so that's not the problem. I'm sure it's the car. Yes, we did get a bit of a tail wind that I think I factored in appropriately so I can't blame it on that. You need to get out there buddy...we miss you!
I'm just going to jet the thing higher than I would have expected to see what happens.
Mark & Nancy Kirby
1971 Plymouth Duster
The Grape Ape
10.20 @129mph 1.32 60'
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Re: ET Prediction vs Consistency
[Re: MarkKirby]
#700789
05/18/10 06:04 PM
05/18/10 06:04 PM
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Joined: Jan 2003
Posts: 5,488 SoCal
Brian Hafliger
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That confirms my thoughts...you not moving enough air through that engine to use that intake! So once again, I believe the heads are letting you down in the HP dept. But that's a different post!
I would start at 87's square. Also, you might pick up more than normal by going to the dominator with that bigger intake. You can only get so much flow out of a 950HP!
Brian Hafliger
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