Counterpoint

Chris recently submitted a letter to the SEB in which FC cars were proposed to be moved to CM. Below is a counterpoint to that proposal which has been submitted to the SEB and given a tracking number of 33582.

TO: SEB, MAC
FROM: Jim Garry
SUBJECT: Counterpoint to Chris Pruett Proposal
DATE: November 28, 2022

This letter is offered as a counterpoint to Chris Pruett’s recent letter, ID# 33424, in which it was proposed to move Formula Continental to C Modified with the requirement it use the Hoosier R60A tire.

While Chris is to be commended for trying to add numbers to C Modified, this proposal would create a new dominant car type in the class which would render the Formula Ford 1600 uncompetitive given equal preparation and driving. This would disenfranchise every autocrosser with a Formula Ford, the dominant car type since 1990 (32 years).

Simply restricting the tire for FC will not create an equal competition footing between FF & FC. While the tire compound difference would be large on cold days, this would not be the case during warm or hot weather when there wouldn’t be a large enough difference to overcome the FC advantages which are listed below. Furthermore, during wet conditions both FF & FC would compete on rain tire compounds and the FC disadvantage of tire compound would be eliminated.

Wheels FF: 5.5” x 13

FC: 6” & 8” x 13

Tires - Dry FF: 20.5 x 7 front, 22.5 x 7.2 rear

FC: 20.5 x 7 front (on a wider wheel than FF), 22.0 X 9 rear

Tires - Wet FF: Hoosier no longer produces a rear bias ply wet tire to fit FF wheels & despite repeated requests have no intention of re-starting. Using the Hoosier FF spec radial wet is a poor choice because they are different heights compared to the dry bias tires and require changing ride heights and re-alignment which is difficult to do on an active grid at a National event.

FC: Hoosier makes bias ply wets that fit FC wheels using a traditional wet compound

Regardless of the issues above, in the rain the FC R60 disadvantage is eliminated

Horsepower FF: ~110 to 115 (depending on which dyno used)

FC: ~150

NOTE: I contacted a Formula Continental racer in mid-November who just had his long rod Pinto dyno'd at 152 HP

Weight FF: 1100 lbs. [Note: FF GCR wt is 1110, Solo is 1100]

FC: 1200 lbs., all engines

WT:HP FF 10 at 110 hp. 9.57 at 115 hp

FC 7.89 at 152 hp

To obtain a ratio of 10:1 WT/HP for the FC using 152 hp, the FC would have to weigh 1,520 lbs. To obtain a ratio of 9.57 the FC would have to weigh 1,454 lbs.

Aero The following are quotes from Ryan Neff of Zebulon Motorsports sent to me in an email dated November 26, 2022. Ryan has successfully designed and fabricated countless wings for autocrossers and road racers.

"Over the extremely old school F2000 wings on all the cars out there currently, even our road-course wing design for Continentals is ~3x more df for similar drag. A real auto-x setup we could make 5, maybe 6 times the DF the stock VD (Van Diemen) type wing package makes. Maybe more. [Jim Garry emphasis.] But, even with the stock wings, the car would be fast. Likely too fast for a tire restriction alone to compensate.”

"To really quantify it we'd need to do some lap sim work to check it. I suspect it'd suggest we'd need to add something silly like 200lbs to balance out the gains from the aero and power difference.”

In closing please consider that beyond the balance of performance issues laid out above, it likely isn’t yet time to be concerned about C Mod turn-out. It can be argued that the last few years have been more difficult for Mod cars than classes which don’t require cars to be trailered. The high cost of fuel has likely impacted decisions of whether to tow to Nebraska & other National level events. It can be reasonably argued that more time is necessary to make any decisions on changes to C Mod due to recent participation numbers. FWIW, in New England Region there will be four FF’s competing during the 2023 season.

Sincerely,
Jim Garry

Wheels	FF: 5.5” x 13
	FC: 6” & 8” x 13

Tires - Dry	FF: 20.5 x 7 front, 22.5 x 7.2 rear
	FC: 20.5 x 7 front (on a wider wheel than FF), 22.0 X 9 rear

Tires - Wet	FF: Hoosier no longer produces a rear bias ply wet tire to fit FF wheels & despite repeated requests have no intention of re-starting. Using the Hoosier FF spec radial wet is a poor choice because they are different heights compared to the dry bias tires and require changing ride heights and re-alignment which is difficult to do on an active grid at a National event.
	FC: Hoosier makes bias ply wets that fit FC wheels using a traditional wet compound
	Regardless of the issues above, in the rain the FC R60 disadvantage is eliminated

Horsepower	FF: ~110 to 115 (depending on which dyno used)
	FC: ~150
	NOTE: I contacted a Formula Continental racer in mid-November who just had his long rod Pinto dyno'd at 152 HP

Weight	FF: 1100 lbs. [Note: FF GCR wt is 1110, Solo is 1100]
	FC: 1200 lbs., all engines

WT:HP	FF 10 at 110 hp. 9.57 at 115 hp
	FC 7.89 at 152 hp
	To obtain a ratio of 10:1 WT/HP for the FC using 152 hp, the FC would have to weigh 1,520 lbs. To obtain a ratio of 9.57 the FC would have to weigh 1,454 lbs.
Aero	The following are quotes from Ryan Neff of Zebulon Motorsports sent to me in an email dated November 26, 2022. Ryan has successfully designed and fabricated countless wings for autocrossers and road racers.
	"Over the extremely old school F2000 wings on all the cars out there currently, even our road-course wing design for Continentals is ~3x more df for similar drag. A real auto-x setup we could make 5, maybe 6 times the DF the stock VD (Van Diemen) type wing package makes. Maybe more. [Jim Garry emphasis.] But, even with the stock wings, the car would be fast. Likely too fast for a tire restriction alone to compensate.”
	"To really quantify it we'd need to do some lap sim work to check it. I suspect it'd suggest we'd need to add something silly like 200lbs to balance out the gains from the aero and power difference.”