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DRR Pro |
Converters are fun !!! We tried a BBC spec'd 10" continental in the Firebird a few years ago. Was slower in every part of the track than our FTI. Roy said it was aggressive in his Camaro, it was a dud in the Firebird. We made more power than Roy too, I was surprised and disappointed . Converter voodo science | |||
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DRR Top Comp |
They're both one way clutches which make the stator active. Active meaning, when turbine picks up enough speed above stall, oil is directed onto the front side of the fin of the stator causing it to turn/spin in the same direction as the turbine. The example for 0% slip at the finish line would be when the turbine, stator and pump are all one down track. The input shaft is splined to the turbine and the one way clutch and stator assembly is splined to the stationary stator support tube. Below stall where the turbine hasn't picked up speed, the oil is directed onto the backside of the stator fin and locked stationary by the one way cluth. Now having said all that, the one way clutch, be it mechanical diode or dog bone sprag allows the stator to freewheel the same direction as the turbine once the turbine picks up enough speed making the stator active above stall. Now here's where it gets tricky, a spragless acts the same below stall, the stator is stationary.It has no one way clutch which allows it to freewheel above stall. So the theory goes like this, because the stator can't freewheel above stall, the stator becomes a restriction above stall, runs hotter and is slower. My guess is this limits what can be done with the stator to affect torque multiplication below stall, and still have an equally fast converter, I think the fast spragless converters have a proprietary stator, to solve / overcome the restriction. I guarantee my TSI spragless is fast, faster than any sprag converter on the market. Can't nobody outrun me. Conventional 23 degree sbc, 3200lbs. | |||
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DRR Pro |
Mike, your car is barely off the starting line beam 0.30 after TB solenoid is released. So I assume that leaving in 1st gear is just for RT. For how long in time and at what rpm do you think this be riding on the convertor stall after launch? Great mph at 6.4x. When are you testing? | |||
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DRR Top Comp |
Legally I can't dial faster than 6.39, otherwise I'll fall under the regulations neck collar, gloves , NHRA license. So I've already been slower than 6.39 at 112.55. The problem for pulling the 14 degree's timing I did, while shift to high simultaneously 3tenths after transbrake release Super Pro bracket racing, is consistency. The reason I could get away with it index racing on a 370 pro tree was because I had the field covered by 030 on the tree, so it didn't matter how consistent the car was. The strategy every round was take less stripe than I won the tree by and win light comes on 100% of the time. With that being said, I gotta find another way to knock the wind out of the sails early in the run, other than pulling a bunch of timing. Try thinking of it as power and not time at stall. Power meaning average A to B power, which results in any given et. Average A to B power at the back tire. At stall it's multiplying torque at the back tire, so I definitely don't want it riding at stall. What I do need it to do is, when it shifts to high 3 tenths after T brake release, it'll look like it needs jet extensions, or in other words the ignition is shut off, after that I need an inefficient converter for the fuel curve to 7200 rpm at the stripe. Which is what I have, a inefficient low stall converter. I had 300 lbs of ballast in the trunk to go a bunch of 6.41's at 109 mph in 100 degree heat and 55 degree semi mineshaft conditions, it won't take much when I pull the lead out of the trunk, as long as it looks like the car was shut off early in the run, trust me. The only reason it's not already done,is because I'm working on getting wheels on the 71 split bumper, so I can back it out of the shop and get the Nova on the lift. There won't be any testing, the car went 6.41 109 off the trailer first hit with 300lbs of lead in the trunk, it'll go 6.41 112mph off the trailer when I change to this converter, no lead in the trunk. 4500 converter. It'll be as consistent as it is now, if the converter is as inefficient as I think it will be. I'm gonna get the dominator carb back on it as well, to up the chances of a successful outcome. This message has been edited. Last edited by: Mike Rietow, | |||
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DRR Top Comp |
The only thing I'm not exactly sure about, is what gear I'm gonna use, I'd like to have it right first attempt. It has been 113 mph with the 3.89 that's in the car now. But I have a 4.10, 4.30, 4.56, 5.00, 5.29 to choose from, I can throw at it. I'm thinking the 3.89 will have the converter REAL inefficient for the fuel curve. | |||
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DRR Trophy |
ok , back on track . if this is going to hit harder where should i be looking at adjustment ? i lowered 2 step to 3500 from 4500 - lower ? I loosened ext and tightened compression on rear shock to hit it harder . MT PBR 29.5x10.5R15 . I raced this weekend .Different track , 15 hours away . Track was a bit sketchy so i gave up on transbrake and footbraked from 1500 rpm . I still managed to spin a few times . Though i did top qualify and lost in the final . Spun and 0.022 cherry . Should i look at taking a swing at rear tyre pressure ? maybe go 17-18 ? Tex | |||
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DRR Top Comp |
You got an aggressive converter, not ideal for radials. The phenomenon that the car is now experiencing is the velocity of the rear end is higher. What you do to control any amount of velocity of the rearend using the clickers dampers. Dampers dampen any given amount of velocity of the rearend. Tighten the extension, loosen the compression. Loosen the front, it should wheely. Add air pressure, it'll drag the boat bumper reciever and dig a groove in the rubber build up on the track surface. | |||
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DRR Trophy |
Thanks Mike , So it it seems i may have gone the wrong way adjusting rears . I thought to hit harder . I will try tightening ext looser comp . Front is already loose . Car is already small wheely , but is probably a bit nose heavy with World iron block . from Sunday https://www.brightdesign.com.au/p525191146 Tex | |||
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DRR Top Comp |
Nice looking Mopar, I dig it Or ya could just tighten extension to slow (velocity) the rear planting the tire. To match velocity of the rearend, with the other converter in play. Try both approaches. | |||
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DRR Trophy |
thanks Mike . that is a footbrake launch 1st elimination pass Tex | |||
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DRR Trophy |
just a little follow if anyone interested . After Portland, runner up so thats ok even with massisve spin footbraking, i went to another T&T here in Sydney . 4 passes tightened up rear ext from #5 from loose to #10 . Spun all passes , even swapped on my Hoosier radials , no go . Went hme and then straight to my workshop and pulled the trans and refitted the footbrake trans . Last weekend raced @ the Australian Top Fuel Championships - 6 passes , 1.49-1.51 sixty leaving from 1500 , and took the win . Zero turn back to its usual numbers . 10.40-10.48 across 2 days DA 15-2500 . So just waiting for a responce from converter shop and back it goes . ## not sure if i noted before but the converter shop said they changed the stator as well though not noted on invoice . and this is probably biggest issue ## Tex | |||
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DRR S/Pro |
So was the weather sub Da? Better than normal or the same? Never mind I see that now . Hoosier radial 9 “ @ 20-23 lbs ,I foot brake, and at 3600# California Screaming! Raceless in California! | |||
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DRR Pro |
First experience with my spragless converter was that I could leave at 800 RPM higher 2-step than I ever had. I kept turning it up until it scared me, then backed it off 400. Diode or traditional sprag makes no difference. I run a 2.10 low range 3-speed. "Despite the high cost of living, it remains popular." Dave Cook N375 | |||
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DRR Trophy |
BP758 , i use the Hoosier 29.5x10.5 radial slick heavy type . I am running 18psi on a 8" rim all i have for spare rims . I am @ 3780lbs there abouts Goob , when i got trans to hook , rebuilt vert , i found i could leave 500rpm lower but have as good or slightly better sixty . With equivilent DA . I was leaving @4500 then dropped to 4000 Tex | |||
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