Zetec Mods Dyno Comparison

[Yofavcracka]

Originally Posted by buffdaddy

horrible example. backpressure and exhaust is crap. I made a post about this a while back in garage talk

ive had 2.5 inch exhaust and 2.25 inch exhaust on my old honda. believe me, i know from personal experience about this.

[bdiddy]

Originally Posted by Yofavcracka

ive had 2.5 inch exhaust and 2.25 inch exhaust on my old honda. believe me, i know from personal experience about this.

do you know how much of a difference you will tell between a 1/4 of an inch difference in exhaust..... on a HONDA at that......

[Yofavcracka]

yes, yes i do. 2.0l vtec.... and we all wonder why grant hates hondas sooo bad, but seriously, i went from a custom made exhaust hat the guy put on before me to a greddy exhaust. 2.5 inch piping to a 2.25 inch and i guarantee it had more pep to it.

i dont know all the specifics Tim, im just stating my experience with the issue.

[cbman]

The trick to resonance (or sound) tuning of the IM is to have these maximally amplified waves arrive at the intake valve just as it opens . The basic mechanism of intake manifold "tuning" or design is to provide high pressure at the intake valve so that the mass flow rate into the cylinder is boosted at a given engine speed or rpm. We do this "tuning" by changing the IM runner length and diameter (area).

Neat link: Runner Length Tuning

[bdiddy]

Originally Posted by Yofavcracka

yes, yes i do. 2.0l vtec.... and we all wonder why grant hates hondas sooo bad, but seriously, i went from a custom made exhaust hat the guy put on before me to a greddy exhaust. 2.5 inch piping to a 2.25 inch and i guarantee it had more pep to it.

i dont know all the specifics Tim, im just stating my experience with the issue.

it was probably mostly in your mind. think about it though, 1/4 of an inch..... in a small honda engine that produces almost no tq..... you might have gained like, 2 hp by going up by 1/4 of an inch, if that.

[Yofavcracka]

Originally Posted by buffdaddy

it was probably mostly in your mind. think about it though, 1/4 of an inch..... in a small honda engine that produces almost no tq..... you might have gained like, 2 hp by going up by 1/4 of an inch, if that.

i went DOWN a 1/4 of an inch... which is why im saying it INCREASED backpressure.

[bdiddy]

Originally Posted by Yofavcracka

i went DOWN a 1/4 of an inch... which is why im saying it INCREASED backpressure.

the whole backpressure thing is a myth, and NOT TRUE

[kpeeks]

Well back pressure is how you get the mpg rating on a car. But its a double-sided blade. Too much/little back pressure your mpg is decreased & if too much your engine starts backfiring too. You can increase mpg by tuning the back pressure & it in turn does gives you engine performance.

[bdiddy]

http://www.uucmotorwerks.com/html_pr...torquemyth.htm

here is an explanation on a honda forum about it. this might be what you were trying to get at, but still dispells the whole backpressure=tq thing.
http://www.hondacivicforum.com/m_39893/tm.htm

[pwhitelock]

Cool, thats good to know. Thanks. Iv had a crappy custom exhaust made up that i wanna replace at some point. I quite like the look of the truebendz one you guys get in the states. I may have to order one at some point