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Discussion Starter #1
I run a screamer sb 440" Mopar similar to sb2. The power range is 7,400-9,000. I an competing in two different venues. I index race 5.90-6.00 wwith power killed. As long as the car is quick on the tree it's fine. I also run larger tires and nitrous for heads up noprep racing.

Lenny fixed me an 8" converter to try and accommodate both venues. The car is still deadly with the index stuff but lost 6mph on motor running all out, go figure. On a 150 hit off the brake and another 150 at .320 the engine rpm, driveshaft rpm and g meter look great. We were looking to have a 7800 stall speed. On the shift it drops to 7400. That should come up when we actually shift at target rpm 9000 instead of 8,500, right? The data shows the slip at 10% at the stripe but it gets better as the engine climbs in rpm. Hopefully on a 1/4 mile pass it will prove to get tighter.

I haven't run car on the bottle for many years. I still have my old PTC 9.5" converter. It is a little tight. Might try it anyway. With some chassis work sense it is a wheel standing monster hopefully the 60 can go from 1.24 rear wheel to mid teens.

I know this is lengthy. Question is running 5.2's wouldn't you expect more than 132mph? I run dexron. Would another fluid pick up the back half of the run? Or is the answer a 9.5" converter for best results? We are looking at less than 1200 HP 3000# car.
 

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Discussion Starter #2
OK no replies no ideas.

Well I'll share what's been tried now.

A 9.5" PTC with 17 fin stator spragless. It was a complete bear to stage. Maxed the intermediates to get even close. Just don't have enough power at low rpm for this one. But, it still ran [email protected] on a mistaken motor pass.

Called Kenny and he shipped out that day a 10" with 8" stator spragless. It stages great. The slip is less than 10% at the stripe. It also 60fted as good as the previous 8". But, clearly was down on wheelspeed and g's. The 330 ft was .5 slow and the et also. It stalls about 7000. Probably would run better with second stage in a lot earlier.

There is no question the UCC is much more productive in the first 200ft. But, it's stalling 8,200. Slips 18% at the stripe. If we could just get this 8" UCC to slip less than 10% and stall 7800 I think we would have something.
 

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Looking at slip numbers with a car geared for the 1/4 seems like useless information to me if your basing slip numbers at the 1/2 way point of a run. Those numbers are really just telling stall speed rather than slip at that point. If the intended stall speed is not where you want it then I would suggest getting that right first and the rest will fall into place.


Hutch
 

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Discussion Starter #4
I would be inclined to agree. But, the slip % is not changing as the rpm climbs. With 18% slip the rear gear will not make a 1/4 mile pass. Ran out of RPM on one kit. Also it slips the same on motor, one kit, and two kits at the stripe. Different rpm for each but the exact same % of slip according to racepak.

This is why I tried a different converter.

I agree none of these converters have the ideal stall speed. We will get there hopefully. Just got to keep trying.
 

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Discussion Starter #6
660ft. Race 1/8 mile mostly.
Test at vmp some and have held it just to see if we gained any efficiency. Did not still 18%.
 

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Discussion Starter #8
Looking at the data so I can actually type what I see instead of what I remember. Lol

The peak rpm is 9000 for the combo. Have not been comfortable with all the other things going on to try different shift points. Shift at 8500 need to try more RPM. Drops to 7500 on the shift. With the 8". And the efficiency gets better as rpm increases as it should on good runs. 8100 at the 660 ft mark with 20% slip. I have seen 18% on some runs. Did the math and only have 9% @8,500 in low gear. Would be tighter at 9000.

Hutch, thanks for the questions. After looking at the data for the 8" I think it needs to go back in car and shift at 9,000. Maybe think about a lower gear. If maxing out et in the 1/8 more gear should make the car run harder then we need more rpm at the stripe. The engine should make more horses even on spray and the converter is closer to minimum slip.
 

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Sounds like you need that 8" converter but you need to shift at 8500 minimum and have a rear gear that better suits the 1/8th mile if you want to optimise the combo. I don't think 9% is horrible at 8500 rpm if your target is 9000 rpm it can only get better as you have already stated. Let us know what happens.


Hutch
 
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