David Wright Posted November 11, 2008 Report Share Posted November 11, 2008 i have a ? our local track used to have a 19 vacuum rule in our local 4 cylinder class ! this is a stock 4 cylinder class ! this year there is no vacuum rule . i was told that there was too many ways around it ! i know it sure kept the racing closer when we had the rule ! anyone have any ideas ? thanks ! Link to comment Share on other sites More sharing options...
1-Crew Posted November 11, 2008 Report Share Posted November 11, 2008 Vacuum rules are used because they are easy to tech but relying just on vacuum leaves a lot of room to play for people that know what they are doing. You can run lots of compression without hurting vacuum. You can use anti-reversion porting techniques and high lift but low overlap cams. You can make up for some vacuum loss caused by cam selection by running more timing at idle and raising the idle speed. You can outright cheat by plumbing an external vacuum pump to the vacuum port on the carb.. The bottom line is, it is supposed to make you leave the engine stock but there are changes you can make to make more power that do not reduce vacuum. If the intent is to keep engines "stock", the only way to do that is by detailed inspection and a very thorough database of what was "stock" for that make model and year. Clearly an impossible task. If the intent is to limit maximum power, one way is to restrict the air into the engine or the exhaust out. Not a popular move but easily enforced, make everyone use a restrictor plate or limit the exhaust to have a mandatory one foot section of a fixed diameter (maybe 1"). Both of these serve the usual stated purpose of limiting cost. Beyond that you can limit tire selection so the extra power isn't really usable as a disincentive to spending a lot on the engine or you can leave it wide open and apply weight limits to equalize competition (which, at least in the beginning, will inevitably result in a few well funded teams running away with the show). Link to comment Share on other sites More sharing options...
HiTech Posted November 11, 2008 Report Share Posted November 11, 2008 david to fix that problem all you have to do is build up you motor and race tps .not many motor rules to abide by .. and crew is correct ..there are alot of ways to beat that vacuum rule .. restrictor works to an exstent ..wieght helps . tires depends ....plain and symple tecking would be the rule .but where do you start with all the different typs of cars you can run with your class .. i know yah had one car that had to much this year ..restriction maybe the answer .... one thing do yah have a left side wieght rule ..tps has different left side rules per typ of chassis you have ..beleive me that makes a differents .man would i love to have 57 percent on the 7 car ...lol anyway there really isnt one answer to this question ..this has been an age old problem with thunders ........ Link to comment Share on other sites More sharing options...
David Wright Posted November 12, 2008 Author Report Share Posted November 12, 2008 is getting around the vacuum rule really worth it in a stock 4 cylinder class that just pays 75 dollars to win ? Link to comment Share on other sites More sharing options...
1-Crew Posted November 12, 2008 Report Share Posted November 12, 2008 Is it worth $20,000 or more to race for a trophy? Lot's of SCCA guys do that all the time.. Some people will always be willing to spend to win, the size of the purse is not important.. Link to comment Share on other sites More sharing options...
HiTech Posted November 12, 2008 Report Share Posted November 12, 2008 david for those who want to win .doesnt matter what the pay is ... they want to win ..we spend a ton more money in our car and travel than you do ..and if you figure what the the top winner gets at our races ..and we were to win all of them .it would not come close to paying what we spend just to race..... look at red river .$1000 TO WIN .even if we had won that race ..it cost $1800 to go race there not counting the $ 350 i spent last time //$450 apiece the first and second trip .. total $ 1250 .... ....now if you would have won ..i would be eating at your house that week ..you would have hit it big ....... Link to comment Share on other sites More sharing options...
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