I have a 2.5" exhaust, and a lot of all-motor guys have a 2.5" exhaust system.

2.5" = 63.5mm

Prelude throttle body is 60mm, and can be bored out to 63.5mm.
B-Series throttle body can be bored out to 63.5mm as well.

Proceed w/ the following steps:
1. Put in a weaker spring.
2. Use a bigger throttle stop screw to always keep the throttle body plate open at least some degrees.
3. Plug all other holes, like the ones for idling, etc.
4. Weld it inline w/ the exhaust piping, or flange it so that it can be removed on race days.

Theory:
At low rpms, the throttle body plate will be closed or near closed for quiet operation.

While WOT or at high rpms, the pressure will push the plate open for max power and sound.

When slowing down or cruising, the spring will push the plate back to maintain a balance of power and sound.

The key is not to use a spring that's too weak, nor one that's too strong.

What do you guys think?

 

great seller he knows his shiet

 

hehe

 

it might work

 

definitely worth a shot.... the worst part isn't failing -- its not trying at all

 

its been done before . ive seen posts on ht about it before so give it a shot!

 

I've thought of using smaller ex pipe , like 1.5 inches , then settin up a dual exhaust with with 2 mufflesr and b pipes and all but only route 1 set straight back with no restriction. Send the 2nd one to an E cuout .The when I want to slam it , hit a switch and a E cut out opens and I'm now on both 1.5 ex's with is basicly now 3 in.. I was going to do it wit 2 of the small bullet style mufflers that are made to put on the primarys of headers or something....
I know,, I'm crazy..lol
I say go for it man...If it works you will sav alot of guys alot oh headaches..

 

Too bad the exhaust won't pust the throttle plate open. It rotates in the center...

You'll either need to help it open or make it pivot off center so the exhaust gas creates a moment about the axis of rotation.

 

<TABLE WIDTH="90%" CELLSPACING=0 CELLPADDING=0 ALIGN=CENTER><TR><TD>Quote, originally posted by drdisco69 &raquo;</TD></TR><TR><TD CLASS="quote">Too bad the exhaust won't pust the throttle plate open. It rotates in the center...

You'll either need to help it open or make it pivot off center so the exhaust gas creates a moment about the axis of rotation. </TD></TR></TABLE>

<TABLE WIDTH="90%" CELLSPACING=0 CELLPADDING=0 ALIGN=CENTER><TR><TD>Quote, originally posted by cpforyou &raquo;</TD></TR><TR><TD CLASS="quote">2. Use a bigger throttle stop screw to always keep the throttle body plate open at least some degrees. </TD></TR></TABLE>

I guess I could also cut off half of the plate so at the least, air flows through it through 1/2 the cross-sectional area.

 

Use a vaccum solenoid to open the butterfly. you shouldn't have to use throttle springs...it will be setup like a boost actuator cut out/wastegate. very simple and easy to make.

 

<TABLE WIDTH="90%" CELLSPACING=0 CELLPADDING=0 ALIGN=CENTER><TR><TD>Quote, originally posted by cpforyou &raquo;</TD></TR><TR><TD CLASS="quote">2. Use a bigger throttle stop screw to always keep the throttle body plate open at least some degrees.</TD></TR></TABLE>

That doesn't matter, it still won't open farther due to air passing by it. Think about it.

 

yamaha uses this on there road bikes its called "exup" a electronic controled damper/butterfly in the exaust allows alot of back pressure for good bottom to mid power, then opens 100% when @ wot, for the flow needed to support top end power. bassically does the same thing as a power valve on a 2-stroke. if u could use the 0-5v output from the tps to operate the butterfly like yamaha's "exup", then it would increase the the bottom-mid power without loosing any top end.
now that would be neet.

 

hmm you could go through all that ot you could buy this

http://www.ultrafitexhaust.com...r.htm

or this

http://www.jcwhitney.com/webap...10101

 

sounds like a great idea
http://www.apexi-usa.com/produ...Num=1
too bad japan beat you to it.

 

seen this on a SE-R ....found the thread on here.....search first y0!

I thought of this a long time ago, but i guess it's not that original of an idea. That doesn't mean it's not a good idea.......It's actually proven to be a good idea. Do it.

 

nevermind. It was used as an exhaust cut-out

 

<TABLE WIDTH="90%" CELLSPACING=0 CELLPADDING=0 ALIGN=CENTER><TR><TD>Quote, originally posted by JCushing &raquo;</TD></TR><TR><TD CLASS="quote">hmm you could go through all that ot you could buy this

http://www.ultrafitexhaust.com...r.htm

or this

http://www.jcwhitney.com/webap...10101</TD></TR></TABLE>

yep...the new bmw 7 series (forgot which one i saw it on) has something similar to this and they use vac solenoids to open the second outlet.

 

It's basically what the Mugen or other twin loop mufflers do right?

At low rpm, it'll make the exhaust loop round. And at WOT, the velocity of the flow is great enough to push open a flap therefore making it a straight through system?

 

<TABLE WIDTH="90%" CELLSPACING=0 CELLPADDING=0 ALIGN=CENTER><TR><TD>Quote, originally posted by mx621 &raquo;</TD></TR><TR><TD CLASS="quote"> alot of back pressure for good bottom to mid power </TD></TR></TABLE>

I bet you wish that were true.

 

<TABLE WIDTH="90%" CELLSPACING=0 CELLPADDING=0 ALIGN=CENTER><TR><TD>Quote, originally posted by Tbone &raquo;</TD></TR><TR><TD CLASS="quote">I've thought of using smaller ex pipe , like 1.5 inches , then settin up a dual exhaust with with 2 mufflesr and b pipes and all but only route 1 set straight back with no restriction. Send the 2nd one to an E cuout .The when I want to slam it , hit a switch and a E cut out opens and I'm now on both 1.5 ex's with is basicly now 3 in.. I was going to do it wit 2 of the small bullet style mufflers that are made to put on the primarys of headers or something....
I know,, I'm crazy..lol
I say go for it man...If it works you will sav alot of guys alot oh headaches..</TD></TR></TABLE>

sorry to call you out tbone if youre infact being serious, but (2) 1.5" tubes are not even close to (1) 3" tube in cross section area

 

<TABLE WIDTH="90%" CELLSPACING=0 CELLPADDING=0 ALIGN=CENTER><TR><TD>Quote, originally posted by dfoxengr &raquo;</TD></TR><TR><TD CLASS="quote">

sorry to call you out tbone if youre infact being serious, but (2) 1.5" tubes are not even close to (1) 3" tube in cross section area</TD></TR></TABLE>

according to math everyone should have learned in the 6th grade they are exactly the same. to find the area of a circle you take .5 the length across and multiply it by pie. in this case we get .75*3.14=2.355*2= 4.71 then 1.5*3.14= 4.71 so the area in the pipes would be indentical.

 

<TABLE WIDTH="90%" CELLSPACING=0 CELLPADDING=0 ALIGN=CENTER><TR><TD>Quote, originally posted by therealpoorboy &raquo;</TD></TR><TR><TD CLASS="quote">

according to math everyone should have learned in the 6th grade they are exactly the same. to find the area of a circle you take .5 the length across and multiply it by pie. in this case we get .75*3.14=2.355*2= 4.71 then 1.5*3.14= 4.71 so the area in the pipes would be indentical.</TD></TR></TABLE>

try pi*r^2 bud

your (2) 1.5" tubes (2*.75^2*3.14) = 3.53 "^2
while the 3" tube(1.5^2*3.14) = 7.065 "^2
so then you only actually have half the area.

to get the same area with 2 tubes they would each need to be 2.12" - dia

-derek


pie does not = pi, lol

and .5 the distance across could simply be called radius so as not to confuze people


Modified by dfoxengr at 1:06 AM 12/29/2005

 

<TABLE WIDTH="90%" CELLSPACING=0 CELLPADDING=0 ALIGN=CENTER><TR><TD>Quote, originally posted by drdisco69 &raquo;</TD></TR><TR><TD CLASS="quote">

I bet you wish that were true. </TD></TR></TABLE>

dont worry, i know its true.

 

quoted by http://www.cartestsoftware.com....html

"the exup alters the back pressure in the exaust system at various revs. it consists of a gate valve in the exaust collector. at lower revs the valve restricts the exaust flow, improving the scavenging of the motor and increasing torque."

if more back pressure dosnt improve low-mid power/torque, then why does yamaha use exup, why does honda use vtec, why do 2-strokes use powervalves, and exaust that have expansion chambers.

 

<TABLE WIDTH="90%" CELLSPACING=0 CELLPADDING=0 ALIGN=CENTER><TR><TD>Quote, originally posted by dfoxengr &raquo;</TD></TR><TR><TD CLASS="quote">

try pi*r^2 bud

your (2) 1.5" tubes (2*.75^2*3.14) = 3.53 "^2
while the 3" tube(1.5^2*3.14) = 7.065 "^2
so then you only actually have half the area.

to get the same area with 2 tubes they would each need to be 2.12" - dia

-derek


pie does not = pi, lol

and .5 the distance across could simply be called radius so as not to confuze people


Modified by dfoxengr at 1:06 AM 12/29/2005</TD></TR></TABLE>

You put about a years more thought into this then I even did when I had the idea years ago.. It was a example used to get a point across, I'm sorry you missed that and took it seriously..