back from summit motorsports park

well i think i messed up!!!!!! dropping my exhaust was a big mistake although i added new 411 gears taking my exhaust off really hurt me only ran a best 13.54 several guys said something about scavaging.because i dont have enough compression and hp to run without exhaust.not sure really what that means hopefully someone here can explain.one thing i can say is the car ran awesome every thing improved 60ft 330ft 1/8th 1000ft.so more runs with the exhaust back on.
P.S. i had a blast drag racing is in my blood now
john

 

Old drag race trick: Build you a set of bolt on collectors about 3 foot long. Then paint a stripe longways down the side with regular paint, not high heat paint. Run the car down the track, shutting off at the end. Cut the collectors off right where the paint stops being burnt off. That should be the optimum length collector for your engine.

Disclaimer: I have never done this, so I don't know really how well it works. I read it in a magazine years ago, just never got around to trying it, but it sounds like it should work....

 

Well glad you got to experience some more seat time, after all that is what you built the car for Live and learn, if I was to drop my exhaust I would put a little different tune on the car, bump the timing some and adjust carb. Main thing is you are not frustrated and having fun

I havent been back to the track since I ran the 11.40 with no roll bar, I am sure they have their eye on me, we have a tough teching track and I am glad we do. I changed my gears to 4.00 from 4.11 so I could drop my rpm a little as I was crossing line at 6,800. All this race talk has got me itchy to get back and go a few rounds

 

yeah i put a set of 24 inch extention on and painted them with primer but none burnt off

 

mike i think im going to just put the exhaust back on and try it that way and see what happens.but regardless of what happens im still having a blast

 

Thats what I would do also, loud is nice but hearing what your wife has to say after a day at the strip is important too

 

I would figure it will run better with the exhaust on

 

What did you say??

 

I took my mufflers off and ran a lot faster, but it was great for the 1/8 mile. After that I ran out of oomph. I like it better with them on.

 

yeah don i think thats what happend to me

 

try useing a smaller pipe like 2.5 or even 2.25. scavaging is where the exhast pulses start pulling the next pulse out of the cylinder. it works both in the header tubes and colectors. as said you dont have the compression to run streight open headers. right now when the vavles are both open during the moment of over lap the exhast needs to still be flowing out of the cylinder to help start the draw of the intake charge into the cylinder. with the open exhast, all the exhast gasses are already out of the cylinder. this make it harder for the intake charge to start entering into the cylinder.

 

thanks bryant that makes sence and i was using 2.5 inch pipe exstentions 24 inchs long
would putting turn outs on help

 

they could. they would create a little bit more back pressure.

 

ok i might try that also but for now i think i will put the exhaust back the way it was and see what happens unless i can get in another test and tune day

 

Have you tried running slimmer front tires?

could pick up some time