Tire Inflation/Deflation - Is it Legal in BITD/SCORE ?

Proformance Motorsport

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Are there any restrictions in running CTIS (Central Tire Inflation Systems) in SCORE or BITD?

We are planning to include CTIS standard in our new V8 SXS 4X4 Buggies and wanted to ensure our customers can legally use it competing in Score/BITD events

Deflate and inflate as you drive with constant tire pressure monitoring, low pressure tire alarms, data logging etc....
 

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SMS81

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Don’t know of a rule against it, but CTIS was removed from the race hummers, but I think Robby May have ran one at Dakar?
 

MikeLeung

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We dont race in sand dunes really...so I'm not really seeing the point for on board tire inflation and deflation.
 

GMS74

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We used CTIS sometimes with the Hummers because AM General demanded it. SMS81 is correct though, as soon as AM General wasn’t paying attention we’d disconnect the system. It’s a very useful feature off road, just not well suited to the types of terrain in our style of desert racing.

Our problems with CTIS were twofold, it’s slow reaction time and the likelihood of failure under race conditions.The terrain we race on changes very quickly, for a mile or so we are in a sand wash then we pop up onto a rocky ridge then onto a high speed hard pack for few miles for instance. The Hummers CTIS system just couldn’t keep up, by the time you finished deflating for a sand wash you were at to low a pressure for the rocky ridge. In addition we were very likely to melt an air line, rip off an air line or have adeflation valve fail and cause a flat (or two sometimes). When Robby got “caught” with his deflation lines running to the intake manifold I knew exactly why after using the Hummer CTIS. I’d bet he was using the manifold vacuum after the restrictive plate to more rapidly deflate his tires (brilliant!). The FIA’s argument was bunk, there’s not enough air volume in four tires to make more engine power for more than a fraction of a second.

The system could be made to work in our style of desert racing with the addition of larger deflate and inflate valves, a large on board air tank and wheels with large air ports on them. We just never found the result worth the effort in our style of racing, particularly with the Hummer already being 4wd. If we ran hundreds of miles of dunes like Dakar it would be a completely different story.
 

Bricoop

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We used CTIS sometimes with the Hummers because AM General demanded it. SMS81 is correct though, as soon as AM General wasn’t paying attention we’d disconnect the system. It’s a very useful feature off road, just not well suited to the types of terrain in our style of desert racing.

Our problems with CTIS were twofold, it’s slow reaction time and the likelihood of failure under race conditions.The terrain we race on changes very quickly, for a mile or so we are in a sand wash then we pop up onto a rocky ridge then onto a high speed hard pack for few miles for instance. The Hummers CTIS system just couldn’t keep up, by the time you finished deflating for a sand wash you were at to low a pressure for the rocky ridge. In addition we were very likely to melt an air line, rip off an air line or have adeflation valve fail and cause a flat (or two sometimes). When Robby got “caught” with his deflation lines running to the intake manifold I knew exactly why after using the Hummer CTIS. I’d bet he was using the manifold vacuum after the restrictive plate to more rapidly deflate his tires (brilliant!). The FIA’s argument was bunk, there’s not enough air volume in four tires to make more engine power for more than a fraction of a second.

The system could be made to work in our style of desert racing with the addition of larger deflate and inflate valves, a large on board air tank and wheels with large air ports on them. We just never found the result worth the effort in our style of racing, particularly with the Hummer already being 4wd. If we ran hundreds of miles of dunes like Dakar it would be a completely different story.
Any concerns about snagging and breaking the air line?

@SMS81 You're correct. The Gordini also ran them.
1599152134484.png
 

GMS74

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A few things we did learn from racing with CTIS. Each wheel needs to be its own circuit, no tying two tires together to a inflate deflate valve. You don’t want one flat to deflate the opposite tire (the stock Hummer system was notorious for this). Also, to facilitate tire changes, some sort of quick disconnect (we used a very short air coupler) is needed at the hub. We also found if you have some slack in the air line from the wheel to the hub the hose can move a bit with impact and is less likely to be torn off. I’d recommend steel fittings on the wheel hoses. Ductility and strength is your friend. They will be hit!

In answer to your actual question, I’ve never seen anything in the rules against CTIS.
 

Racer Tim

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We used CTIS sometimes with the Hummers because AM General demanded it. SMS81 is correct though, as soon as AM General wasn’t paying attention we’d disconnect the system. It’s a very useful feature off road, just not well suited to the types of terrain in our style of desert racing.

Our problems with CTIS were twofold, it’s slow reaction time and the likelihood of failure under race conditions.The terrain we race on changes very quickly, for a mile or so we are in a sand wash then we pop up onto a rocky ridge then onto a high speed hard pack for few miles for instance. The Hummers CTIS system just couldn’t keep up, by the time you finished deflating for a sand wash you were at to low a pressure for the rocky ridge. In addition we were very likely to melt an air line, rip off an air line or have adeflation valve fail and cause a flat (or two sometimes). When Robby got “caught” with his deflation lines running to the intake manifold I knew exactly why after using the Hummer CTIS. I’d bet he was using the manifold vacuum after the restrictive plate to more rapidly deflate his tires (brilliant!). The FIA’s argument was bunk, there’s not enough air volume in four tires to make more engine power for more than a fraction of a second.

The system could be made to work in our style of desert racing with the addition of larger deflate and inflate valves, a large on board air tank and wheels with large air ports on them. We just never found the result worth the effort in our style of racing, particularly with the Hummer already being 4wd. If we ran hundreds of miles of dunes like Dakar it would be a completely different story.
The other part of using vacuum to deflate the tires and this is even more important on small lighter weight vehicles is that at higher speeds the centrifugal force is expanding the tire and deflation is even slower, i know Robby talked about this and this would be an even larger issue on a smaller SXS type vehicle when the air pressures are on the lower end.
 

Proformance Motorsport

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A few things we did learn from racing with CTIS. Each wheel needs to be its own circuit, no tying two tires together to a inflate deflate valve. You don’t want one flat to deflate the opposite tire (the stock Hummer system was notorious for this). Also, to facilitate tire changes, some sort of quick disconnect (we used a very short air coupler) is needed at the hub. We also found if you have some slack in the air line from the wheel to the hub the hose can move a bit with impact and is less likely to be torn off. I’d recommend steel fittings on the wheel hoses. Ductility and strength is your friend. They will be hit!

In answer to your actual question, I’ve never seen anything in the rules against CTIS.
Thanks so much
 
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