svanni

After seeing what US Gear is doing with their "D-celerator", it sure seems pretty simple to just build your own. I've read previous posts about others thinking about it, but has anyone done it yet ?

How hard could it be ? A piece of 5" pipe, a rod & disc (for the butterfly valve), an actuator, and a 3-way toggle. Doesn't have to be to any tight tolerances, you actually want some "blowby". Clamp it on behind the cat.

Something you might have to do is put a pressure sensor on the engine side of the butterfly valve to make sure you're not building too much. If you are, just drill a hole or two in the butterfly until you're where you want to be.

Somebody with a milling machine call me - I'm doin' it.

dodgezilla04

the materials have to withstand the egt's though. at 1200 degress preturbo, you will see 900* at that butterfly valve. the bushings it rotates in must withstand that temp and still be able to turn without sticking. good luck, post some pics.

stock03

What about installing it towards the end of the exhaust system?

TIMMY22

I would think it would leak like an SOB around any connections. probably have to weld the exhaust sold around the joints.

scottsjeeprolet

You could use graphite inpregnated bronze for the butterfly bushings.

Mglass1045

They've got a bushing repalcement kit. You could probably just use them, cause well, that's what they use. Would you have to use a cast housing, or would there be another material that could handle the heat? I'd love to have one but the price is a big issue for me. Keep us updated!!

JimmieD

I note that you refer to "...some blowby...' for the ex-brake. You also mention a pressure sensor to make sure you're not building too much pressure. The question I have had which I haven't gotten an answer for is just how much blowby you want and just exactly what is too much pressure?

The only clue I've gotten so far is that the Jacobs unit, of an entirely different design, requires something referred to as '60 lbs. springs' on exhaust valves. I don't know if that is the actual valve seat pressure [doubt it very much] or what, but it is for a single cylinder. I would guess it's 60 psi but seems there's something missing from the equation that might explain how high the actual seat pressures are. I don't even know how to do the math to translate that 60 psi to the actual seat pressure of say a 2" exhaust valve.

I see 3 ways to regulate exhaust back pressure:

1] an orifice or bleed hole in the butterfly plate.
2] a pipe bypass around ex-brake
3] a spring loaded actuator of a specific pressure less than that which would cause engine damage.

I will be building my own also. As mentioned in another thread, I figure on starting with a very oversized bleed orifice and then gradually closing it until ex-brake performance helps deceleration. Still scares me that I'll get sucked into "If a little is good, more is better...." to the point KABLOOEY!

I happen to have a small engine cylinder sleeve/liner that is of top quality high-nickel steel @ 4" diameter so it's the perfect size for exhaust brake on my 4BT's 3" exhaust. I also found a really nice piece of 3/16" stainless steel plate, already stamp cut into a slightly concave round, that will do for the butterfly. Figuring on at least a Grade 8 stainless 7/16" bolt for pivot pin, but may need 1/2". Stainless exceeds my tool's capabilities so I'll fab a mockup out of mild steel and grade 8 non-stainless bolt, then pay to have the final copy welded up.

May try an electric solenoid actuator bt doubt there's enough oomph there to close the butterfly against exhaust pressures even with leverage, don't know. Might go with 'over center' linkage so it's locked closed, then pushed open with another solenoid?

Please post if you find out anything about maximum safe pressures or exact bleed orifice/bypass piping size. Hope yours works...!

RustyJC

The exhaust brake functions by making the engine act like an air compressor during the exhaust stroke of each cylinder. If you placed the e-brake at the end of the exhaust system, you would have so much fixed clearance (a compressor term) that the e-brake would be much less effective. That's the reason that a Jacobs e-brake bolts to the turbocharger exhaust housing - to minimize the fixed clearance. The closer to the engine you place it, the less fixed clearance you have and the more effective the e-brake will be.

Rusty

svanni

JimmieD,

A few thoughts.

I've read that US Gear makes two "sizes" of exhaust brakes: A 35 psi version, and a 60. Their website shows a graph of braking power, RPM, and pressure. That graph is on a 0 to 35 psi scale. So if it were up to me, I'd start somewhere around 20 psi, and work up to 35.

When I mentioned "blowby", I was thinking about the butterfly disc being smaller in diameter than the ID of the pipe. My thought was that when the butterfly is in the fully closed position, the disc DOES NOT come in contact with the ID of the pipe. I've heard the soot can cause sticking.

Lastly, and I know you know this, if the butterfly valve is centered on the pivot axis, then all "exhaust rotational forces" will cancel. You just need the actuator to overcome the forces of the soot on the bearing surfaces.

Keep us posted.

svanni

Here's a 4" cutout for $190.

http://www.buickgn.com/electricexhaustcutout.htm

If you had the flanges, you could bolt this in-line, somewhere behind the cat. Drill the proper sized hole in the butterfly, and you're done.

Question about cutouts: are they either full open/full closed, or can they be stopped at any position ??? That would be handy to adjust the amount of braking.

RustyJC

Something to consider....an exhaust cutout is designed to handle perhaps 2 PSIG back-pressure in the exhaust system, not (let's say) 60 PSIG that could be generated in an exhaust brake application.

Rusty

duner

so far the answer to the original question stands at "nobody"

Moose10

I may be totally wrong here, but I think the 60# valve springs are only required on the 12V engines. Guys running Jacobs brakes on 24V's like mine don't need any changes.
svanni, If you can pull this off, and have a reliable unit, more power to ya ! I'm not saying it can't be done, but I definitly lack the engineering skills to build something like that I paid my $625 and pressed on.
Please keep us updated on your potential project. I'd like to see the end result

DJ

How about a long pto cable going to a valve at the tail pipe with a spring to keep pressure under 30 psi, just pull the cable **** and stop. A little leakage around the clamps would help release excess pressure. You could use a potato wrapped in tin foil for a valve, just replace it every 20 stops with a fresh uncooked one. You would always have a good supply of baked potatos around

Raspy

I'm planning on doing it too. To a VW 1.6 with turbo. The new exhaust brake will be mounted in the usual place, at the manifold outlet. It's just a piece of stainless pipe with a butterfly on a shaft. Some clearance around the butterfly to limit the backpressure. An arm on the butterfly shaft with a cable running up through the dash on the Samurai. Simply pull a "T" handle on the dash for downhill braking or for quicker warmups in the morning. Simple.

Wetspirit