Do you make your own collectors, or do you buy pre-made ones?

 

I did, it made 183rwhp. lol

For testing I make my own. Once its where I want it, then I purchase one built to spec from SPD. On this car however I dont know if the 1-2 hp is worth the cost. Its a very very cheap test mule.

 

Man megaphones are a pain to fab, so I know your pain. Its using a megaphone, but no reverse cone. I have not yet seen a gain with one, so have been leaving them out.

 

That they can't is an old wives' tale. They do, no problem.


It's not ideal for power, but they'll run just fine.

 

do you mind share your finding why 2.5 works better?
thank you

 

I don't have a finding, I simply just thought it would be so. I don't have evidence or theoretical math to back it up.

 

nice numbers great job..

 

Most AM drag cars well at least the ones that run good all have mufflers. There's a reason for that and only testing will reveal it.

The piston motors are more sucessfull with the reverse cones. Piston motors are more effected than rotaries when dealing with high overlap.

There's no substitute for testing.

The one thing I've learnt when dealing with NA rotaries is that there is no set equation when designing a header/collector. Every combination requires a specific setup to be most effective. Everything else is just a compromise. The same holds for intake tuning.

 

Thanks Ito!

 

look what you've done now ... you've got the big boys in ... How do you guys play around with megaphones? I'd like to play around with some when i'm redoing my exhaust.

 

From what I tried so far testing is that a full exhaust setup will like a 4-6" megaphone, and a header only setup will like 12" or more. As Crispeed said there are so many combinations, I could be way off from the ideal setup however.

 

Forget the megaphone, it's all about the expansion chamber!!!! I can't wait until I get mine from ISC. There is a thread about the GB in the race tech section, and the highest NA HP thread has some information on them.

 

id actually like to see how much gain that give over a straight pipe in that section. and then against a reverse cone megaphone.

 

Hmmm I guess I figured out an easier way then cause it only takes me 30mins to make one. Wasn't hard at all. Now the merge collector was a challange.

 

Wow never knew this. Well now I guess I need to try both ways to see what kind of difference it makes.

 

[QUOTE=crispeed;

The one thing I've learnt when dealing with NA rotaries is that there is no set equation when designing a header/collector. Every combination requires a specific setup to be most effective. Everything else is just a compromise. The same holds for intake tuning.[/QUOTE]

Please let me know if i get this right:

it is better to design/build a exhaust header length(wise)and intake length(wise), so both systems have their best effeciency at the same rpm, to get the best "drafting" so to speak,
right?

 

yes you don't want to tune your intake for best ve at 7500 rpm then tune your exhaust for peak torque at 5k. unless you want tour car to be really flat and not make much power.

 

Would make a nice generator though!


It boils down to a lot of R&D.


It sure gets the job done!
Nice radius on the header exiting the ports!

 

Do you do it the same way I do ... lay it out the pattern on metal plate then roll it?

 

Hmm that seams kind of hard. I don't have that kind of equipment so I have to get creative. I take your average medium sized paper cup (like what you would get from Burger King and cut it in half. The taper on these cups are perfect. I then trace that pattern on 3" diameter exhaust tubing and use my miter saw with metal cutting blade to cut it. Join both peices together and tack weld. The two ends will be football shaped so you will have to shape the ends to make them perfectly round. Using this method I have one end at 2.5" and the other at 3.5". Takes about 30mins to do it.

 

ya thats another way too, probably better your way

 

I just think some people don't like to read.

 

very sweet!!!! ive bee wanting to go n/a on mine but with some itb's and im actually thinking of doing just that!!


congrats !!!!

 

you might be interested in my mid pipe expansion chamber exhaust street port six ports scca e-production cars we make(195whp 48ida 38choke 1st gen -230whp sec gen efi stock intake ported stock t-body) have shown gains on even stock motors
in back to back testing on 2 sec gen its cars running(motec) identical set ups the pipe showed gains of 4-7whp between 4-6.8k and after peak(8200)gains at 9000 were 9.8 hp over none pipe set up.if you are interested drop me a email or call me at 954-825-8288

 

230whp at what rpm?