Viper Tires on CSX3170

[Cobra #3170]

We ran the Viper fronts square on the Cobra last weekend at the Pleasanton GG event and found that they do not perform well below about 75 degrees. Scott set fast time of the event and won the shoot out but not by a large margin as he usually does. He was from .5 to 1 second faster than our other competitors instead of 1.5 to 2 seconds. Looking at the data those little 25 aspect ratio sidewalls do not put power down well. The foot print is shorter and slightly narrower than our Bridgestones but we thought compound would still be superior. Our major competition next week at the year end championship shoot out all have the 355/30/19 rears (we can't fit bigger than 335/30/19) witch put power down really well so we have a big task trying to be competitive. We will try to improve weight transfer front to rear to see if that helps but as always in this game any change has both positive and negative affects.

I have attached two more boring autox videos for those of you interested enough to watch. The first Video is from an airport autox the only thing of interest here is the engine flexibility. Scott starts in second gear and makes the whole run in second at about 55 seconds in he is over 9300 rpm. The other video is Pleasanton with viper fronts on all four wheels.

https://www.youtube.com/watch?v=owpI...NccUhpJ1Q&t=0s

https://www.youtube.com/watch?v=sa7c...NccUhpJ1Q&t=0s

[Anthony]

Oh, So Beautiful !!!

[t walgamuth]

I'm guessing by watching him work his shoulders there is manual steering in it...? Anybody know how many turns lock to lock? All work done there in first gear, right?

[Cobra #3170]

Originally Posted by t walgamuth

I'm guessing by watching him work his shoulders there is manual steering in it...? Anybody know how many turns lock to lock? All work done there in first gear, right?

That is a custom power gear, you could never drive this car with a manual gear (one turn lock to lock). He is making big corrections and is always ahead of the car. Even with power it is hard to really move the wheel that fast I hurt both my shoulders trying. We don't want to lose steering feel so not too much boost. The whole premise of the new de-stroked engine was to give us a first gear range of 16 to 68 mph but to also prevent bogging on slow corners, Rear gear is 4.88 and first gear is 2.2. The car explodes off slow corners now compared to our old set up that had more power but bogged on slow corners. It was 4.27 rear with 2.2 low and would only turn 8200. GoodGuys corners can be really tight so we have to be careful to keep manifold velocities up or we get poor throttle response and stumble. When we run SCCA events we just use second gear and have a workable range of 30 to 85 mph with no shifting. Shifts cost time unless you have a DCT or automatic.

[t walgamuth]

What engine are you turning 9300 rpm? Yeah running without shifting is the way to go. You running a carburator? I have a TBI by Holley I am planning to install. I have a cam that will give nearly all its torque at about 1800 and pulls right up to the limited 6500 rpm limit.

[Cobra #3170]

Originally Posted by t walgamuth

What engine are you turning 9300 rpm? Yeah running without shifting is the way to go. You running a carburator? I have a TBI by Holley I am planning to install. I have a cam that will give nearly all its torque at about 1800 and pulls right up to the limited 6500 rpm limit.

It is a Shelby FE block with Blue Thunder heads 440 cid. Fast XFI port injection, Sonny Briant crank, Carrillo rods, Dailey dry sump, 15 to 1 CR, Chevy mains and Honda sized rod bearings, MSD ignition, titanium intake and exhaust valves, really good valve springs and a cam with .818 lift and over 287 degrees duration at .050. 820 hp @8200, 790 @9000 and 562 lb/ft at 7500. Over 430 lb/ft @ 3250 so not bad on low end. Wilson 1650 cfm Throttle body on Victor JR highly moded manifold. Headers are 21/8 ' primaries with 31/2" collector. One reason I destroked this engine was to kill low end torque. Too much low end torque just results in wheel spin and that slows the car. Soft cut is 9300 hard cut is at 9500 rpm, we have seen 9400 numerous times.

[t walgamuth]

That is some outrageous rpm! .818 lift? Outrageous too! My hat is off to you and your engine builder!

[Ron61]

Great videos and thanks for posting them. You are doing great and as with any change, there will always be some other things that it affects. The car looks and sounds great and Scott did a great job. Congratulations and good luck in the next race.

Ron

[t walgamuth]

I am finding my elbow room on the left arm to be very restricted. I'm sitting too low to put my elbow above the door edge and keeping it inside restricts movement. Maybe that is why you have gone to one turn lock to lock?

I had one turn in my Lotus 7 replica with adjustable electric steering. I'd have done that in the Cobra but not enough room down where the assist motor has to go.

[Moto One]

Second video at Pleasanton, bring back memories, I had Jack Frost as a mentor back when I was 19 year old driving CSX3263. Sure looks tight now at that site, I also never got out of first gear there, at the Ford plant (Milpitas, same time frame) once in a wail there would be a course that second was useable, as was Cal Expo. We are getting new Axels out of NC in SFR0012 and will be looking forward to a few autocross events next summer.

Mark.

[Anthony]

CSX3170,

What transmission are you using ? Jerico ?
Who built your engine ? Engine shop in MI ?

Beautiful Car ! Beautiful Package !