Author Topic: FED & Transbrake  (Read 7368 times)

Offline JrFuel Hayden

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    • Hayden Enterprises Speciality Wheels
  • Your Best Time: 6.02, 236 mph, 1/4 in 1973 Div 3 TF Champ
  • Your Engine: SBC, Alky, 403 ci, Best 6.99 @ 190 & 409 Hemi
  • Your Track: Bakersfield
  • Your Vehicle: 225" FED NHRA Heritage Jr Fuel
Re: FED & Transbrake
« Reply #15 on: May 25, 2019, 01:43:52 PM »
Wow, Greg, 500 rpm under stall, that would be way too high for us , we stall 8500-8700 with the SBC JF car , but what seems to work good for our car is leaving around 6400 rpm giving us 1.01-1.04 60' times. Keep in mind the higher you launch at the quicker the RT you get.
Again it's all about your combination , Greg you are running a blown alky SBC, running in a breakout class, we are running a 10k rpm injected alky no break-out JF . We need to get some tire spin going at the hit, yours makes more torque because of the blower, and you no-doubt run a 8" tighter converter than my alum light weight 7" converter. I still run a 7" but tighter converter with our Hemi [ more torque].
We shift at 9600-9800 rpm with the SBC, and 9500 with the Hemi.
How high you launch has to do with what RPM the motor comes on at, track prep, tires , tire pressure, rim width.
The other issue is tire shake, I think tire shake is caused by TOO much bite dead hooking then unwiding of the side walls. Too much bite , I let some tire pressure out so the tire works more on the edges of the tire thus reducing the footprint . To check that out I use my temp gun at the turn-out and read temps across the tire, ei hotter on the edges. On our Gooyears we run 5 1/4 to 6 1/4 lbs, depending on track conditions. i have heard as low as 4 3/4 with bead locks on a low torque engine combo. My  GY guy has said that more and more racers are having tire shake issues because the tracks are over preping the tracks [ TOO much VHT] that is why I'm going to try some other tires, like 31x10.5wx15 M/T and M&H. No doubt I'll need to try different tire pressures [ MT like high pressure] launch rpm , and rim widths. 
Jon C. Hansen

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