engine brake question/idea

[jaluhn83]

Maybe I'm wrong but i always thought when you let all the way off the throttle at speed there was no fuel being delivered at all. At least not to the injectors.

I'm not sure if this is true or not. There's an idle governor that comes into play at min throttle but I don't know if it'll completely shut off fuel flow or if it just reduces it to a minimal amount. I would guess there's still some fuel flow even at min throttle and high rpm.

 

[jaluhn83]

Oh, I know how good exhaust brakes can work, got one on my Fummins, thing is godsend. Problem is, as you said, the cost - in comparison I got the materials and skills and time to build a throttle blade, so no out of pocket expenses there. But if it is in fact a silly idea that's more dangerous than it's possibly useful, well then it likely won't happen...

How, dare say I ask, were you planning to build one? It's not as simple as one would think because you need a good valve seat and a bypass valve. Then the actuator and all the other auxiliary parts. And sealing the shaft, and.....

I'm all for fabricating stuff, but at the same time I've learned that sometimes it's not worth it.

 

[79jasper]

I'm not sure if this is true or not. There's an idle governor that comes into play at min throttle but I don't know if it'll completely shut off fuel flow or if it just reduces it to a minimal amount. I would guess there's still some fuel flow even at min throttle and high rpm.

I don't think it does completely stop fuel. With my chevy 6.2 engine braking down a offramp at night, I can see a pretty good haze in cars headlights. My 7.3 idi does it a little also. So really I'm not sure what all that means.
But Mr. Mel would probably know for sure.
If it was that big of a deal, people with manual trans could just kill the fss power while braking.

LCAM- do you really think you'd need that big of one like off a Detroit? (I have no idea what one looks like though)
I mean have you seen the small opening for the turbo intake hats? That being said, I know for a n/a application you would need a bigger opening.

 

[LCAM-01XA]

Well, if you have the time and materials, could you build it for the exhaust instead? Just an idea...

Exhaust brake is a very different animal, for one thing the materials I have are fine for use in clean cold air but may not be ideal for dirty hot exhaust gases. Then I gotta find a way to seal the shaft (so no exhaust leaks are present), and devise an actuator system, and some sort of backpressure monitoring/reference... If it's to be done right it's a lot of work, and quite frankly I ain't got that much patience. I know my limitations, I can modify an existing exhaust brake to fit my needs, but building a proper one from the ground up is beyond me.

How, dare say I ask, were you planning to build one? It's not as simple as one would think because you need a good valve seat and a bypass valve. Then the actuator and all the other auxiliary parts. And sealing the shaft, and.....

Well since I'm making the blade smaller than the housing opening anyway to provide enough airflow so the engine can idle even when blade is closed, perfect seals and bypass valves and all that are not needed... And remember this thing will go in front of the filter, so anything that passes by it will be stopped by the filter much like how it happens in factory form. It's really just a simple butterfly flapper to limit the amount of air the engine can pull thru the intake housing, a use very different from that of a gasser's throttle body where precise metering of air is crucial to proper engine operation.

LCAM- do you really think you'd need that big of one like off a Detroit? (I have no idea what one looks like though)
I mean have you seen the small opening for the turbo intake hats? That being said, I know for a n/a application you would need a bigger opening.

I dunno how big the DD valves are, I'm sure those installed on 8V92s or 12V71s are gonna be massive, but something from one of their smaller engines may be a good candidate... It will probably need some modifications so it don't close all the way (after all I don't want it killing my engine, just restricting airflow to what's needed for normal idle), but it's still a better start than devising something from the ground up. Again, all this is if it even exists in 4" size, I haven't looked that much into it yet.



Also, about the RDT - couldn't I still run a CDR, but relocate it so it connects to the intake before the butterfly valve? Kinda like how it's done on turbo engines, CDR on valve cover and from there a big hose to intake ducting. Then it won't be seeing any of the vacuum formed inside the housing, so no chance of sucking the crankcase dry of oil.

 

[79jasper]

Maybe you could drill some holes in it, so that you wouldn't have to worry about it closing too far. Just enough holes so that it'll idle like 100 rpm lower than normal with it fully closed. I don't know, just some random ideas.
I agree with what you said on the cdr.

 

[LCAM-01XA]

That random idea is actually not random at all - older Ford gassers do indeed have holes drilled in their throttle blades, they are not large holes and do not serve as primary idle air feed, but are holes all the same. If the engine has a low and unstable idle and an adjustable-bleed adapter for the idle air valve is not available, slightly enlarging the hole in the throttle blade can be a feasible solution.

 

[79jasper]

Well good. I thought it may be easier than making something to keep it from fully closing.

 

[79jasper]

Any update to this idea???

 

[racin460]

http://www.ronsfuel.com/flying_toilet.cfm Buy one and let us know how it works?

 

[79jasper]

http://www.ronsfuel.com/flying_toilet.cfm Buy one and let us know how it works?

Da fuq is that? Roflmao.
I think the idea was to "junkyard" build something. Not spend a few grand. Lol
I could buy and setup a parachute for that price.

 

[RLDSL]

jaluhn83, I dunno about the valve seals either - that's why I'm asking questions before doing anything stupid. From what I've read on the internets the 7.3 IDIs actually have too good of an intake valve seal, apparently it don't let enough oil thru to lubricate the valve stem and guide properly and eventually causes the valve guide to wear out faster than it happens on a 6.9 w/ their older non-positive seals. I'd think if these issues are present, the 7.3 valve seals should hold up quite well under vacuum. But thanks for pointing out this concern, maybe someone more experienced w/ different styles of valve seals can shed some light on this...

.

THis would only apply to original equipment valve stem seals, and there aren't many 7.3s still rolling around that have never had the heads off. Once off, all replacement valve stem seal sets are retrofitted same as the 6.9 with the umbrella seals on the exhaust. They found the positive seals a cause of eating exhaust valve guides on the 7.3s ( however when I built mine, I put positive seals all around knowing that I wasnt going to use anything but synthetic in it and I'm comfortable with the extra lubrication and not worried about guides, but that is not what you will find in most engines )

 

[LCAM-01XA]

Any update to this idea???

Negative. And there won't be any any time soon. I'll necromance this thread after I've fabbed stuff up and got some testing done, don't you worry about that...

http://www.ronsfuel.com/flying_toilet.cfm Buy one and let us know how it works?

Absolutely, as soon as I get the proper drag-strip assault vehicle. My IDI sadly is a far cry from one. lol

THis would only apply to original equipment valve stem seals, and there aren't many 7.3s still rolling around that have never had the heads off. Once off, all replacement valve stem seal sets are retrofitted same as the 6.9 with the umbrella seals on the exhaust. They found the positive seals a cause of eating exhaust valve guides on the 7.3s ( however when I built mine, I put positive seals all around knowing that I wasnt going to use anything but synthetic in it and I'm comfortable with the extra lubrication and not worried about guides, but that is not what you will find in most engines )

In that case guess I'm in luck, when I was replacing the valve cover gaskets methinks all I saw under there were positive seals... Could be wrong, but since relocating the CDR requires modifying one valve cover anyways I will verify the type of seals once cover is off again.