honda throttle body for cut out

[dsmcurse]

so i have this idea to use a TB as a exhaust cut out. i think to releive some pressure out of the down pipe would do some good. i tryed to mock up a stock mitsu TB under there. and she seemed a little to bulky. a friend gave a honda TB to try. the outside shape of it is considerablly smaller than the mitsu one i had for this.

i know i could buy a electric cut out for cheap but the natural design of those are to be spliced in line past the flex pipe section. like way under the car. heres my idea. the very first bend in the down pipe, where it 90's to go under the oil pan, right there at that 90 i put in a old throttle body so that when it opens some air can blow straight out to the ground.

as far as the opening and closing of it. i think i could get a choke cable from napa for like 5-10 bucks that way when i pull it the flapper stays open. then i push the cable in to close it.

i have a boost gauge tapped into my turbo header to moniter exhaust manni pressure. the gauge is a diesel boost so it has no vacume to display. that and i feed the gauge with copper hose so it wont melt like a nylon hose would.

any feed back on a cut out right there at that first bend in the down pipe would be great. thanks for any ideas or suggestions

 

[Voodoo262]

Sounds like a really rigged way of doing a cut-out. Do you think the extra 6" of pipe and one 90* bend you shave off would really be worth the hassle of opening and closing the TB with a cable? If your downpipe is mandrel, I can't see it making a huge difference

 

[sniver]

Interesting Idea. My thoughts are It will sound like it has a exhaust leak when closed, they're designed to let air through when closed, not sure if they could be closed 100%. Next issue would be the throttle body o-ring will melt.

Not sure what the plate is made of, but I bet the housing is cast aluminum. How well will it hold up to the heat of the exhaust. I know they've made aluminum catbacks, but the temp is down significantly by then.

If your'e set on having a cut out, and can weld, it may not be a bad experiment. Worse thing is it doesn't seal, or distorts horribly. Then you cut the flange off, weld a new one on for a real cutout and go on your way.

I think the odds of this working long term, and sealing completely are low, but I'm only guessing. I have one off a prism I would try if I had a mild steel downpipe, I don't have the provisions for welding SS here. So prove me wrong!

I like tinkering, hacking sh!t up, and going against the grain. I put a sport bike motor on a off-road buggy,so how much common sense do I have?

 

[dsmcurse]

well soon me and myn buddy will be making are third trip to the all wheel dyno at cobb tuning (surgeline) in portland. i hope to have the homemade cut out on the dyno to see any gain from the reduced amount of back pressure.

the throttle body does indeed flow air when closed. but thats all on the outside edge. not in the actual flapper hole. the hole im gonna cut right at the first bend in the down pipe will be the same size of hole in the honda TB. a small lip about a 1/4"" will be welded on, then the homemade flange for the throttle body. the flange will only allow air to go into the flapper section. NOT the outer edge.

the shaft inside and the actuall flapper should hold up fine. i dont worry about anything melting. i have thought about carbon build up in there tho. but i work on the car so much i doubt that would ever be a issue.

the down pipe is real live 3" turbo back with apexi N1 3" straight through muffler. it has no cat or any other muffler of any kind. the 44mm wastegate off of the hx40 is external dump with a 14" dump tube. so the car is already loud any how.

i think a free TB cut out perfectly placed would be nice. who knows, if it works great maybe it'll be a new trend.

 

[914g63gsx]

Sounds like a really rigged way of doing a cut-out. Do you think the extra 6" of pipe and one 90* bend you shave off would really be worth the hassle of opening and closing the TB with a cable? If your downpipe is mandrel, I can't see it making a huge difference

I agree. Why don't you just get an electric cut out and have a pipe shooting straight down if your worried about it going down. Just my .02

 

[dsmcurse]

cause i want it to relieve pressure out of the system as close to the turbo as possible. my buddy is rigging a old 44mm external wastegate in the same spot that im talking about. i think a TB is better than a old WG. the cut outs you buy are to big and bulky and are intended to be spliced in mid way down the exhaust piping. like under the belly of the car

it makes more sense to put the cut out VERY close to the turbo. any one else on here watchin there exhaust mannifold pressure? any one tap a boost gauge into there turbo header? try it. you'll be surpised by the amount of pressure build up in that manni.

if your intake manni pressure is 18psi (boost) and your exhaust manni pressure is also 18psi. then your engine is working at its peak. after my buddy saw the amount of exhaust manni pressure he was building up he switched to twin exhuast. (yes i know, dual mufflers on a 4 cyl = rice) but not when you dyno at 517awhp it dont.

he now has dual exhuast and is rigging a wastegate very close to his borg worner turbo to be a cut out to reilieve downpipe pressure. im gonna attempt to do this with the help of a honduh throttle body. we'll post the differance in back pressure change after this is all completed.

i would recomend tapping a boost gauge into your exhaust mannifold to any one that is taking there performance serious

 

[sniver]

Sounds like a really rigged way of doing a cut-out. Do you think the extra 6" of pipe and one 90* bend you shave off would really be worth the hassle of opening and closing the TB with a cable? If your downpipe is mandrel, I can't see it making a huge difference

I agree. Why don't you just get an electric cut out and have a pipe shooting straight down if your worried about it going down. Just my .02

Is that really needed? You don't think he knows its a rigged idea? Why not come up with a list of probable points of failure, or sucess. If he wanted to get talked into buying a electric cutout, he'd ask if its worth buying .

In his whole endeavorer, he'll be one flange away from a electric cutout if thats the route he decides in the end. But really electric cutouts suck pretty bad to,they work well while they are new, but two winters and they're probably seized up. This happened on my buddies camaro, both seized up after not using them a whole winter.

cause i want it to relieve pressure out of the system as close to the turbo as possible. my buddy is rigging a old 44mm external wastegate in the same spot that im talking about. i think a TB is better than a old WG. the cut outs you buy are to big and bulky and are intended to be spliced in mid way down the exhaust piping. like under the belly of the car

it makes more sense to put the cut out VERY close to the turbo. any one else on here watchin there exhaust mannifold pressure? any one tap a boost gauge into there turbo header? try it. you'll be surpised by the amount of pressure build up in that manni.

if your intake manni pressure is 18psi (boost) and your exhaust manni pressure is also 18psi. then your engine is working at its peak. after my buddy saw the amount of exhaust manni pressure he was building up he switched to twin exhuast. (yes i know, dual mufflers on a 4 cyl = rice) but not when you dyno at 517awhp it dont.

he now has dual exhuast and is rigging a wastegate very close to his borg worner turbo to be a cut out to reilieve downpipe pressure. im gonna attempt to do this with the help of a honduh throttle body. we'll post the differance in back pressure change after this is all completed.

i would recomend tapping a boost gauge into your exhaust mannifold to any one that is taking there performance serious

Wastegate, designed for exhaust, but not strait through...
Intake throttle,out of its environment, strait shot..

I do agree that its a much better idea to dump as close to the turbo as possible, and making the exhaust gas have as little impedance as possible.

Pauls cars has the cutout in the down pipe, but has it turned to come out the driver side of the bumper.

 

[50trimgst]

The tb won't work unless you Do lots of modification to it. Now there are lots of people who have made a waste gate work. It's real nice cause you drive around town with normal exhaust then when you hit boost it opens. Plus I do not think getting all the pressure out right away is best. Reason being my dp gasket blew and nut backed off. Now this let's pressure out right away and let me tell you it killed my bottom end. I vote waste gate I know I'm going to attempt it.

 

[sniver]

The tb won't work unless you Do lots of modification to it. Now there are lots of people who have made a waste gate work. It's real nice cause you drive around town with normal exhaust then when you hit boost it opens. Plus I do not think getting all the pressure out right away is best. Reason being my dp gasket blew and nut backed off. Now this let's pressure out right away and let me tell you it killed my bottom end. I vote waste gate I know I'm going to attempt it.

Please do explain, I'd love to hear this one..

 

[BrokenTsi]

I run this cutout in place of my test pipe.

Stainless Exhaust Electric Cutout Bypass w Remote 3" - eBay (item 120671503744 end time Feb-12-11 11:09:38 PST)

Damn, it used to be 99 bucks. It uses a key fob remote. Works awesome. I welded on vband flanges and clamped it on to my exhaust. I notice a pretty good increase in spool by running it right off the end of my downpipe.

 

[sniver]

I run this cutout in place of my test pipe.

Stainless Exhaust Electric Cutout Bypass w Remote 3" - eBay (item 120671503744 end time Feb-12-11 11:09:38 PST)

Damn, it used to be 99 bucks. It uses a key fob remote. Works awesome. I welded on vband flanges and clamped it on to my exhaust. I notice a pretty good increase in spool by running it right off the end of my downpipe.

Thats pretty slick and cheap. How long have you had it?

 

[dsmcurse]

im full v-band so a blown gasket isnt ever a prob. the idea is if i can fab a freebee and it works awsome, then great. the waste gate down there is a good idea, but to have full controll of its flapper you would have to rigg something. right....?

im super curious to see the back pressure change with a cut out closest to the turbo. think all that pressure breathing out of two holes insted of just one.

does any body else tap there exhaust manni to watch the amount of pressure build up in there? if so please post your turbo set up and exhaust manni with differance in intake manni pressure and exhuast manni pressure

 

[BrokenTsi]

Thats pretty slick and cheap. How long have you had it?

I've had it for about a year now.