Tyre pressures?????

68northantsdart · Post by **68northantsdart** » Tue May 20, 14 7:30 pm

So with the 14 inch steels on we use for moving the car around there were roughly 4.25 turns of the prop to 1rotation of the rear wheel?

68northantsdart · Post by **68northantsdart** » Tue May 20, 14 7:31 pm

It's in third les at around 5700/5800 rpm

Pete · Post by **Pete** » Tue May 20, 14 7:34 pm

Sounds like 4.10's which is pretty good for a Drag Racing application.

You seem to be pulling a lot of MPH (good bhp) for a less than impressive 60 foot time - I thought that the gears would have come out numerically lower (i.e. 3.23:1 or 3.55:1)....very interesting........

68northantsdart · Post by **68northantsdart** » Tue May 20, 14 9:37 pm

The cars in for paint but hoping to make the first rwyb in June to test for dragstalgia so will see what happens then I guess, I've learnt that I was running the slicks far too low so maybe that will help.we can't find the timing slips but we are both sure it ran 115/120 mph at 12.20-12.40 ish. My brothers convinced that it seems to be flat out though as it goes over the line??

Les Szabo · Post by **Les Szabo** » Tue May 20, 14 9:41 pm

mmm......

60 Foot E.T. : 1.55
1/8 Mile E.T. : 7.05
1/8 Mile Trap Speed : 96.41
1/4 Mile E.T. : 11.17
1/4 Mile Trap Speed : 120
1/4 Mile Trap RPM : 5,905
this is at 425hp and weight of 3000lbs...28" slick and 4.10 gears.

60 Foot E.T. : 1.61
1/8 Mile E.T. : 7.32
1/8 Mile Trap Speed : 92.88
1/4 Mile E.T. : 11.60
1/4 Mile Trap Speed : 116
1/4 Mile Trap RPM : 5,689
At 380hp

All I can think of is that it hooks on the hit and then spins till it hooks again on the next shift or that it just doesn't hook, but thats suprising with SS springs...was that with the brake used or just footbrake?....

68northantsdart · Post by **68northantsdart** » Tue May 20, 14 9:43 pm

Just off the foot brake, did have nitrous but we took it off as a real old system so we never tried it?

Les Szabo · Post by **Les Szabo** » Tue May 20, 14 9:48 pm

only way is to see the car launch and a few of the old hands should come up with a solution for its lack of ET

68northantsdart · Post by **68northantsdart** » Tue May 20, 14 9:50 pm

I hope so!! All your help is much appreciated and will be paid for in beer!! Lol

Pete.S · Post by **Pete.S** » Fri May 23, 14 10:46 pm

Another quick way for giving yourself a baseline for you own set up/car weight/ temperature / and tyre side wall support as they are all different is observe the flattened section of tyre in contact with the ground this ideally should be around 10-11 inches once this is achieved take a pressure reading and this is your base line, if car is unstable top end add .5 at a time

Mick · Post by **Mick** » Fri May 23, 14 11:03 pm

Mark a white line with a shoe marker on the rear tyres, then film the car from the side as close as possible, then play it back in slow motion and you will see what the tyres and the suspension are doing. Tyres will crease on the sides but it only needs to be a small amount, excessive wrap up or the part of the tyre on the track creasing is too much. I learned to pump the tyres up untill they spin and then back the pressure down a little.
Mick

68northantsdart · Post by **68northantsdart** » Sat May 24, 14 2:25 pm

Thanks for the advice, we're hoping to test the first or second weekend in June so I'll give everything a try as recommended

Pete · Post by **Pete** » Sat May 24, 14 2:29 pm

There is a RWYB at the end of May at the 'Pod.

We hope to have the Barracuda ready for that and up the Nitrous and trans-brake revs!!!

Les Szabo · Post by **Les Szabo** » Sat May 24, 14 4:53 pm

I always used to get the car running its best on motor first before hitting it with squirt, you'll learn more about the N20 that way but that takes more track time....good luck with it....cars got mid to low 9 sec potential running it soft or maybe a high 8 with 250hp, maybe not on a RWYB track though?...should be much faster than my old slug '69 was with that motor.