I hope it doesn't rain thurday night. I plan on going to Atco raceway for a few runs to try out my new mods. The R sure feels like it pulls harder in Vtec but I'm not sure if it's just all noise or not. I'm not sure if the 2.5" straight pipe is steeling some power due to the lack of back presure. My best run with just a Comptech Icebox was 14.85X, I've only been to the 1/4 mile run twice for a total of 5 runs. Let me know if anyone on this board plans to be there. I wouldn't mind meeting fellow Honda Tech members. Anyway do you guys think I'm loosing power due to tha lack of back pressure with my current setup. I know I'm headed in the right direction for my future mods, but right now is my R slower in a 1/4 mile run. My mods are in my sig. Thank you in advance for your reply.

 

Anyone

 

I think you'll be ok.

 

I hit almost 200whp allmotor with stock ITR exhaust.
For your mods, ITR exhaust is fine.
Unless you WANT that raspy annoying sound of a can?

 

But am I gaining or loosing power with my setup?

 

your talking about the straight pipe right? it should'nt lose much power....mugen

 

What I meant to say is 2.5" straight pipe exhaust over stock exhaust with my mods am I gaining or loosing power?

 

So I'm loosing power?

 

i wouldnt worry about it, you might be losing torque but i think youd gain it back in the high revs..

 

So would the 2.5" straight pipe give me a better 1/4 mile run over stock with my mods?

 

well its hard to say. If you make more power it just might help your 1/4 mi times.

 

Anyone Know

 

http://www.superhonda.org/board/show...623#post249623

good stuff there..

 

NO, as long as you have no harsh "steps" in the connections of your exhaust, you shouldn't be losing any power anywhere... "not enough back pressure" is a shad tree mechanics tail of what happens when you go so big on the exhaust diameter that the flow loses too much velocity... reducing proper exhaust gas scavenging... if it's a smooth fitment, your "pipe" may be good for another 5-10hp... I think Dan swears by them on ITRs...





[Modified by Zeus, 8:51 PM 10/2/2001]

 

I have a question. Why did you run 2-1/2" tubing and then install a 2-1/4" muffler?

The above link has a lot of good info.

 

I didn't see any 2.5" magnaflow mufflers, and the next step was 3" and I knew I didn't want to go for that. Why do you think this will cause a problem? Oh and I fell for my machanics good to have some back pressure myth. Is 2.5" straight pipe to a 2.25" muffler going to hurt my performance with my current mods?

 

Magnaflow has a lot of 2-1/2" mufflers and resonators, just not with tips. Neck downs don't help performance. How it necks down can effect it even more.

Lets see, if the mechanic told you that back pressure was good. I know how he installed the muffler. He probably slid the 2-1/2" tubing OVER the inlet of the 2-1/4" muffler. Muffler inlets are expanded in order to slid the corresponding tube size into the muffler. For example, a 2-1/4" muffler will have a 2-1/8" ID through the muffler but the inlet and outlet will be 2-1/4" ID or about 2-3/8" OD. So a 2-1/2" exhaust pipe may slip over your muffler's inlet. Now you have a sharp edge inside the tube and then another neck down inside the muffler. Not the best thing in my book.

A muffler guy once told me that something like the above doesn't make a difference because the exhaust doesn't care what the inside of the tubing looks like.

 

He cut the 2-1/4" inlet of the muffler back to where it expanded to 2-1/2" and welded the 2-1/2" straight pipe over the expanded 2-1/2" inlet part of the muffler. Should it have been done another way?

 

Not sure if I follow. Are you saying the muffler has 2-1/2" OD tubing through it but the inlet was reduced/necked down to an ID of 2-1/4"? If this was the case he should have just expanded the inlet to a 2-1/2" ID and slid the straight tubing in.

 

No the muffler is 2-1/4, but the inlet that was 2-1/4 that had a small section that expanded to 2-1/2 so he cut the 2-1/4 inlet section off and welded the 2-1/2" straight pipe to over the 2.5" section of the inlet.

 

I'd still get rid of it and go with all 2-1/2" components. Maybe George Knighton will post some pictures of his system that we installed today on his ITR. It only uses a 2-1/2" tip that I sanded a little bit to a brushed finished which I thought looked pretty good. The muffler I used was a sst 4" x 9" Magnaflow with a center/offset set up with the extra long (22") resonator. He and Victor can comment on the sound if they like.

 

i think youll lose top end , , , , ,i always have when i went with that set up . you wont notice it too much , but i think you will lose, that has been my exp with that set up .

 

ttt

 

you might be slower in the beginning due to loss of low end power but gained back up top.