quote:

Originally posted by CURTIS REED:
I did quite a bit of high gear racing in 2017. I am a footbrake car though so I can't comment about consistency of leaving off the brake in high gear. I can comment on the car and heat.

Heat is your biggest concern. If you don't have 2 coolers on board or one of the fluid circulation pumps to use between rounds you will probably have to have a fan of some sort to help cool. I started using one of the carpet drying type fans that I could just blow air under the car (roadster in my case). I later got a cheap electric leaf blower and made a pvc tube that had an ell on the end to blow air right on the pan. Worked great. It's really only a big problem when you get in the later rounds and time gets short. Instead of being 190° after a run it would be 220° usually depending on ambient temps.

A WAG about the car leaving is probably .020 slower RT.

Here is a nice thing about being able to do it. I have changed to high gear only in the middle of a race when the track started getting iffy. It also messes with people when they think they know you. The bad part is that it feels sooooo sloooooow. LOL It took a little getting used to it. My car went from high 5.90s to mid 6.20s and I lost 1-1.25mph It definitely make the race look different for your competitor.

I have had guys spot me and pass me early only to drive back around them when they think you are covered. My car was stupid consistent doing it. It just gets boring.

Curtis

quote:

Originally posted by Curly1:
That is impressive. I think in your case the old Shogun? flexplate type cooler may be a big help. They were a very thin fan that bolted between flexplate and convertor and they moved a lot of air around convertor and transmission. Not sure what ever happened to them but you could feel them moving air and heat out.

quote:

Originally posted by wideopen231:

WAIT WINNING GET BORING? New concept there. I do think that if you know number it will change it would confuse hell of of competition. 1st round 5.90,2nd rd 5.90 and 3rd rd you dial 6.20.

quote:

Originally posted by markemark:
If presently using a 1st gear TB, here’s something you can try that won’t cost you anything if you have a delay box with a timer output or ignition with timer function. What this will do is give you very close incremental numbers of what to expect when leaving in a gear other than 1st.

Using your delay box timer output to shift your transmission, program the timer to turn ON at 0.001 and OFF at 0.300 after TB release. This will NOT give you consistent RT numbers, but all the incremental times will be very close (faster) to .015 as if leaving in a gear other than 1st.

To use the above method and HAVE consistent RT, you program the ON time to 0.32 and OFF to 0.62. This allows the car front tires to clear the Stage beams as consistent as your normal rum, but will reduce (faster) all the incrementals by another 0.05 to 0.08 over the first method I list.

Like Curtis wrote, “had guys spot me and pass me early only to drive back around”, this very often happens when your opponent is dialed up to 0.30 faster than you when leaving in a different gear. You will be chasing.

My experience is that you can possibly run 5 to 7 mph faster 1/8 mile than your opponent that is dialed the exact same as you when not leaving in 1st gear.

quote:

Originally posted by Lenny5160:

I can't remember the minimum 'safe' shift time that he gave, but I remember Greg at FTI saying that shifting too early at WOT is hard on stuff.

quote:

Originally posted by FTI:
Here I am.

High gear valve bodies are very popular. I will first say that everything has its time and place. We are running these now behind BIG (2400) power with great success. I have spent many hours developing converters and valve bodies to make them live and be consistent in this environment.

As far as shifting early such as .02 to say .05 on a power glide here is what happens. As with any car when the car leaves the starting line and before the turbine in the converter meets 40% of impeller speed (you can see this on your Data logger) torque multiplication IS occurring!! So lets use an easy torque multiplier of 2.5:1 as any typical hard hit converter would have for our scenario. 800 ft lbs of torque multiplied by 2.5 equals 2000 ft lbs. So now we are asking our transmission to release the band and apply the clutch under the heaviest of loads(the first 60FT) and at 2000 ft lbs of torque. Premature clutch wear will occur regardless of line pressure!!!! It can be done and has been done. It may not cause immediate failure but I promise your transmission will not like you. When you leave the starting line in high gear the clutch is already applied not trying to come to a stop to hold. You ask "why doesn't it bother it when it shifts down track". Well because torque multiplication is gone and therefore easier to stop the clutches. This is why when you do go up in power you must put more clutches or more line pressure to combat the time it takes for the clutch to stop.

TH400 shifting early!! Much easier on this unit as the gear ratio difference, the size of the clutch and the fact that the clutch is not inside the drum that reacts in low gear makes it a better candidate for shifting early. In a powerglide a component has to release and one has to apply to shift. In a th400 a component never releases,it just keeps applying more components with each other!!

We currently have a high gear only car that many of us know (Danny Nelson) who has been 6.0's @ 240+ for many runs in high gear only without hurting the unit.

Greg

quote:

Originally posted by DANGERBOY:
Mine slowed down .5 in 1/8 little over 1 mph 2800# SBC with 4.56 gear.I had no heat issues with trans.Did notice reaction time window did open up.Had to adjust delay box around .060,and some suspension changes.