free horsepower
10-08-02, 07:55 PM
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free horsepower
im going to build a 1st gen for road racing and want to get as much power as possible. The class has srict rules and only alows smog equipment removal, straight pipe exhaust, and high flow intake filter. i was wondering what the best diameter pipe would be for the exhaust. A company that builds these cars use a 2.5 inch straight exhaust, but that seems a little big to me for such a small displacement engine. what do you guys suggest? also what are some suttle things i can change to get a few extra horsepower.
10-08-02, 08:15 PM
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I have dual 2-1/4" exaust, one off each port, it is very nice. you might have to use a pre-silenser, they are starting to ban un-baffled rotarys. grab a k&n filter and one of the top cover things that are filters too, any old holey carb bottom pan will work. or you can get the k&N filter for the stock pan and use dryer hose to get cold air from the ground. use the same idea if you are running a SE model car with EFI, get a cone style filter from you local rice shop.
10-08-02, 09:31 PM
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im preping it for the pro-7 class. im not really fimiliar with all the classes but i think its even more restrictive than spec rx-7. i figured 2.5 was way to big. the engine will be a stock internal 12a with only a few mods. i guess i can try a few different sizes, but i just want to pick your rotorary brains. right now i have a honda prelude, and know practally nothing about rotorarys. anyways thanks for the suggestions
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10-08-02, 11:37 PM
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I'm just getting into Spec 7 racing myself and the SCCA Rules sheets I've seen say 3'' is the max and I've heard thats what some of the guys run. It seems a bit crazy to me but I guess you wouldn't need to worry about any restriction.
10-09-02, 12:30 AM
#9
http://www.sevensonly.com
guys check this link out (:
has the rules and specs
Spec 7 is more restrictive than Pro 7
guys check this link out (:
has the rules and specs
Spec 7 is more restrictive than Pro 7
10-09-02, 12:58 AM
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Run 2 inch primary pipes (preferably long), collecting into a 2.5 inch pipe somewhere before the diff, a straight through muffler, maybe a pre-silencer or two and you can't go wrong.
10-09-02, 08:33 PM
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thanks for the link, buti have personal talked to sevens only racing. In fact they are the ones who got me interested in the pro-7 class. the exhaust from sevens only racing is 2.5 inch and supposedly makes 2 more horespower than any other exhaust. that 2.5 just seemed a little big. in a way i wish the class was less restrictive, but oh well thats makes it cheap and thats the reason i want to get into it. it is the only serious racing i could possibly afford.
10-10-02, 12:01 AM
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i was talking to a guy that was in the spec-7 series, dont remembe his name, but his car was pretty damn sweet. they were racing on road america about 2 miles away from where i live THANK GOD 
, if any of you guys ever get a chance to go on it, trust me, do it, its one of teh funnest things i have EVER done!! its unreal.
, if any of you guys ever get a chance to go on it, trust me, do it, its one of teh funnest things i have EVER done!! its unreal.
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