My Pro7 car has basically no exhaust. Just the "reactor", as required by NASA's Pro7 rules, and then a dump pipe about 2 feet long.

A few questions.

1) What are other racers using? Length and mufflers/silencers?

2) I'll be driving at Laguna Seca, and they have a noise limit, 92db or so. What is recomended to quiet the exhaust?

What I'd like, is a bolt on pipe to lengthen the current exhaust to get the ball of fire behind the car, not under. Then have another pipe the same length, with a muffler or silencer or _____ to run for reduced sound.

Thanks,

Todd

 

The longer the pipe, the better. IIRC Mazda recommended a length of 10 feet from port to outlet for max power potential.

You'll get many different answers. Some say to go with 2 2" pipes till over the axle then to a 3" muffler, others say 3" all the way back.

Check out http://www.iscracing.net/ They've got a very nice IT exhaust setup, but I'm not sure what they've got for a Pro-7.

 

Another key piece, per the pro7 rules is a mandated max of 2.5 inches.

I have 2.5 all the way back to a dynomax ultraflro round (straight thru) mounted and exiting in the stock location.
Its "Laguna" quiet. 87-88.5 DB @ Buttonwillow in 65 degree dry weather.
I'm going on the dyno soon, but it doesn't appear to have hurt power at all.

Hve you run the pro7? Have any pics?

Marcus

 

It's strange that you say that. I was going to suggest that exact same setup. I guess it does work good!

 

Thank you for the links and tips.

Some info:

I went to a few track days in my street car with www.clubz.org out of the SF Bay Area , but decided that my car worth too much to me, to ball up.

I found a built Pro7 car, for pretty cheap. I bought it in Feb '04. I've tracked it just once, at a ClubZ event, and had a blast. I tried again last week, but worn shaved RA1s and a cracked brake rotor stopped my day short.

I'd like to put more time into driving it, and work towards a racing license.

Here are some links to some pics, taken from the guys at Gotbluemilk.com:

http://gotbluemilk.com/040308/20/IMG_2059.jpg
http://gotbluemilk.com/040308/20/IMG_2893.jpg
http://gotbluemilk.com/040308/20/IMG_2964.jpg
http://gotbluemilk.com/040308/20/IMG_2981.jpg

and the only one from last week:

http://gotbluemilk.com/web041111/20/HT4U5124.jpg



-Todd

 

Cool :tu: Love to see a new pro7 in Norcal.

What tracks have you run?

 

So far, just Thunderhill, once in my 7, 3 times in my street car.

Just signed up for Laguna Seca 12/15.

 

You'll love it, just watch the sound limit.


Marcus