Spec Racer Ford for TT4 rules questions

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PostPosted: Fri Mar 09, 2018 10:02 am
I think you're going to have more success on a NASA forum than here. I don't imagine many (or any) of the folks on this forum have looked into this.

kesizewi wrote:HI,

Looking at the "non-production" rules for TT4, I see that the gen1 and gen2 spec racer ford prototypes are approved for TT4, but the gen3 cars are only approved for TT3 or higher. For both, no mention of "additional aero mods" is made in the rules, unlike some of the other non-production vehicles listed.
I have a few questions.
1. If using a gen2 car, taking the 0.6 model specific mod factor, am I able to also take the "OEM aero" mod factor if I make no aero changes? If I don't take the oem aero factor, can I make additional aero mods to the car (wing, splitter)?
2. May I use any engine / engine mods in order to hit my power target, or do I have to use an original, unmodified gen2 SRF motor?
3. If "yes" to #2 above, then why do the gen2 and gen3 cars have different classifications? The only real difference is the engine. Chassis/aero are identical.
4. Can additional tubing be welded into the space frame of the car? This would serve multiple purposes (safety increase, stiffness increase, weight increase).

please help

I did not find the right solution from the internet.

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PostPosted: Fri Mar 09, 2018 11:42 am
The most significant classification factors for the Gen3 are both the additional horsepower and the lower minimum weight. At 1,560 lbs, the power to weight ratio of a 130hp engine would be right at 12:1. I expect most Gen 3 engines will actually dyno signficantly higher than 130, so now you're below the TT4 threshold of 12. As I recall, tire mods offset as they're narrow, but not DOT compliant.

The easiest adjustment to keep it in TT4 is the weight. There's plenty of room for ballast in the side pods and new SCCA rules allow ballast in the center cockpit area. For example, if you had a 135 HP engine, then ballasting to 1,620 would put you right at 12, again.

Since this is a tube frame (not space frame) car, it's possible to "mod" in additional tubing, though I'd suggest the ballast route is a lot simpler way to go.

We did extensive aero mods for the Enduro car we ran in NASA. There's definitely some performance advantage at higher speed tracks, but there's also loss in straight line performance, so your mileage will vary. I doubt that it would benefit you much in performance or benefit your TT classification.
Bob Breton - SRF 51 - San Francisco Region

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