Time for a Torque Converter??
 

Hello and Happy LD!

While my current setup has been doing well all things considered, I am looking to bump things up a little to gain better ET . I can eek out a 10.5 in perfect weather, but normally hanging around 10.7 to 10.8 at 125-127mph. I have some room to grow while still staying within my 6pt bar rule.

The areas that I am thinking that will have the best bang for the buck are:

-- Higher stall converter - currently a tight 10" Continental, "Jim Hand special"

-- Larger cam

-- 2 step ignition, either activated by a foot brake switch or install a trans brake.

For starters, i have access to an almost new 8" PTC converter that flashes at 4500. I called PTC, and the tech felt that converter should work well for me. Although I only have 3.50 gears, I am running a low gear set in the trans and a short 26" drag radial.

Before I go through the work of swapping converters, what is the concensus of using this unit behind 600hp and 3,350 race weight? Or, will I not be able to take advantage of the higher stall without a cam change, etc?

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What does your current converter flash to RPM wise? What cam are you currently running?
Do you have an idea what RPM your combo makes peak torque at?

Current flash right around 3k. Using SD "OF 2.0" with peak torque coming in at 4,400/4,500 rpm. Peak HP around 6,200.

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I would try the new converter. It will get you in the peak torque range quicker.

Just for reference, my last motor made peak torque around 5200-5300 rpm. I had a 9" converter in it. Flashed to 3600. I sent the converter back to loosen it up came back and would flash to 4300
Before rework on converter it went
10.40s at 130mph with 60' in the 1.60 range.
After converter rework
10.20s at 129 mph. With 60' in the high 1.40s

1.52 60foot and 125 mph are a good match.

the 1.52 @ 60foot has very little room for "improvement";maybe 0.1 sec is being optimistic.
I would think the combo 60foot can benefit from DRIVER TECHNiQUE, to find that best 60foot:
Tune mixture, Accel Shot, and Total ADV.Probably done.
Rear suspension slap-bar tune; probably done that too.
and finally, the Driver launch technique: off-idle reaction vs holding RPM (and foot-brake, trans brake). I think the lower RPM converters deliver the low 60foots with off-idle launch.

Simply-put; Keep driving.

I am sure there is plenty of room for driver improvement :) I do have quite a few sessions run with this combo, trying many different shock settings, caltrac pre load, carb tuning etc. Not a whe lot different launching off idle vs 2k rpm with foot brake.

Here is a launch video from last wknd where my best run was about 1.55 60ft., 6.75 and 105mph on the local 1/8th track.

https://photos.app.goo.gl/3MABQVY9DxZAyBEq6

Again, I am sure some improvement can be had with the current combo, but am looking to take a little bigger swing at it ....

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You might benefit from a gear change and a higher stall converter to get you where you need to be. When I drove on the street, I had 3.73's and 4.10's with a 3800 stall and was a good all arounder

Interesting outcome at the track yesterday where I turned an identical best 60ft time of 1.526 from a previous run this year and last fall! Good news on yesterday's run is I also managed a personal best of 10.515 @ 128.96 in so-so air conditions. Was about 2k on the DA and some moisture in the air.

Trying out a new converter is getting very tempting... For reference, Darby was kind enough to video a slow motion launch attached here

https://youtu.be/C4PdQmWAL-4

Goodness.

I wonder how much additional HP is needed to turn 10.5 into 10.00? is it like 50 HP?

Not gonna find that in a Converter right?

May find it in swap off the 850&Torker II. I happen to have a 10.0 ET capable Torker I laying around ( okay a couple left) that matches well to a Spacer-ed 1050, Spreadbore. Can handle the 850.

I have just switched from the 10" continental 3200 to a 9.5" TSP 4800 and gone from 1.60 to 1.52 with no other changes. It put me in my torque band much quicker and has really helped.

Can I ask what shocks you have on the front?

Good to know, thx. I am running the viking 18-way warriors at all four corners. I did install the Smith Racecraft rear shock mount, which brings both shocks inboard and in front of the axle.

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I'm not sure about finding 50hp..its utilizing and tuning the combination to its fullest...I'm 350 lbs heavier with a very similar engine ..and fully expect to get to 10.5 with a 3200 converter and 308 gears.
I'm pretty sure Lee can whittle his times down to very low 10's at his weight..it takes time.

"I'm pretty sure Lee can whittle his times down to very low 10's at his weight..it takes time."

True, but I also like short cuts :)

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Me too..but sometimes my shortcuts go the other way!

If U can I would get all the specs on that converter, it can flash good for you and be tight up top, but too loose in the middle.
I still think its worth a shot to try it, Nothing to lose but your time and possibly ET lol, I'm sure it will pick just depends on how much
with the gear u have

First off, the car is gorgeous!! Personal opinion, do the converter swap and soften the rear shocks. But one change at a time.

UPDATE
 

Went ahead with the converter swap. First impression on the street was negative- way too loose! But... decided to make a run at the 1/4 mile today and my first run actually scared me with a personal best 1.43 60ft time- with no other changes! My previous best was 1.52 with the Continental. I followed that run with a personal best ET of 10.48 (previous 10.51) and the best part is I hit the brakes on that run as I had the other car beat in our 1/2 second index race.

On another 10.48 run the MPH was 126.6. As seen here in this helmet cam video, the flash on this 8" PTC is too high for me, as it almost feels like I am driving a CV transmission with very little RPM drop on shifts. I had to bump my rev limiter up a little so I could run a full 6500 RPM- which was the RPM across the stripe- so plenty of slippage.

But i consider this test a success. It showed me that a looser converter will noticeably improve my 60ft times- just need to have this one or another tightened up a little. Here is a video of the tach and another under the car...

https://www.youtube.com/watch?v=z8sYA-tSRUA

https://www.youtube.com/watch?v=V-Uj-b-wXtk

Congrats on finding that 0.1 in the 60foot. And MPH and ET walked up for getting rpm north of 6000 rpm for 10.48 seconds :eek:

I think that 8" flashed to 6000 and sat at 6500 the whole ride. You are making good power up there. Which my Street/Strip translation is you make great power from 4000-6500 as well. This is the region where a well-matched Converter will yield similar Strip results, yet show tightness on the Street pullaway.

Rear Axle seems very well behaved.

The Street/Strip will be more Strip with that 8", butt hay, some Fans on a remote cooler and a Trans Temp Gauge may be all you need.

Hmmm, Can the 10" be re-worked for higher Stall, and sell the proven 8" ?

PTC is saying they can tighten up this converter, but too your point an 8" may not be overly friendly on the street. In reality, my street driving is literally a few hundred miles per year, so I should probably not put too much emphasis on it.

I have a note out to Lenny at UCC as well to get their thoughts, as I do hear a lot of good remarks about their product.

Just for kicks, I am dropping my exhaust for a day at our local 1/8 mile this wknd running the loose converter. Supposed to be high of 52 degrees, so hopefully some clean air for a few fast runs.

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