puff of blue smoke at higher rpm decel

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Re: puff of blue smoke at higher rpm decel

Post by user-23911 » Sun Feb 04, 2018 3:35 pm

If you don't have turbos then you should be using alpha N tuning, not MAP.
But I think I said that a year or so ago.

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Re: puff of blue smoke at higher rpm decel

Post by Belgian1979 » Mon Feb 05, 2018 6:31 am

The plate was bulging towards the valley. A bit riddled about that. Only cause I can think is an intake backfire

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Re: puff of blue smoke at higher rpm decel

Post by Newold1 » Mon Feb 05, 2018 9:42 am

I think the bulging is definitely from back pressure (backfire).That bottom plate is too thin. Since you really don't need to get into this area a lot I would fabricate a 3/8" thick plate with a couple of 1/2" threaded holes with plug for future clean out, etc. Then weld that plate all the way around the outside and be done! That thin plate and that slippery silicone is never going to seal properly. ELIMINATE POSSIBILITIES!

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Re: puff of blue smoke at higher rpm decel

Post by Belgian1979 » Mon Feb 05, 2018 2:13 pm

I evaluated possibities of drilling on the top but there is simply not enough room.

Meanwhile I found a 2K glue that holds up to 200°C and is oil/fuel resistant. Maybe that will work with some extra bolts on the short ends.

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Re: puff of blue smoke at higher rpm decel

Post by Newold1 » Mon Feb 05, 2018 5:10 pm

I am guessing you don't have a welder available who can tig a thicker plate for you?

I also think there might be another problem with that vacuum plenum in that it may be filling somewhat with gasoline vapor and possibly a small amount of fuel and that mixture is lighting off in that chamber and creating a pretty strong explosion in that plenum that did the blast forming? That area is pretty big in volume and I am thinking it might be possible?

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Re: puff of blue smoke at higher rpm decel

Post by mk e » Mon Feb 05, 2018 7:12 pm

Belgian1979 wrote:
Mon Feb 05, 2018 2:13 pm
I evaluated possibities of drilling on the top but there is simply not enough room.

Meanwhile I found a 2K glue that holds up to 200°C and is oil/fuel resistant. Maybe that will work with some extra bolts on the short ends.
The glue is very unlikely to work. You could add a bunch of m3 or m4 screws along the edges......better to plug the holes and move on.

This is your manifold right?
DSC03192 (1).jpg
It looks like 6" or so or runner you have easy access to. Drill and tap 1/8" npt pipe. Put an not to barb fitting in with red loctite, grind it smooth in the runner, add rubber hoses to a canister and be done with the silly under manifold plate that will always be a failure waiting to happen.

You could tap the holes on the bottom an hose metal lines or maybe braided. That would work.

A way stronger plate is probably an option too...3/8" or 1/2" thick at the flange, you could mill ribs to lighten it if you were so inclined. That would probably be reliable .

But just trying to glue what you have.....not so much
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Re: puff of blue smoke at higher rpm decel

Post by Belgian1979 » Tue Feb 06, 2018 3:59 am

That's and old picture, image it with airboxes attached to the horns, the fuel rails connected, wiring looms running over it, the CNP coils that sit above the stacks and finally the throttle linkages. Plugging with attachments for a 3/8' alu line for all 8 is going to take a huge amount of room and I would only have place right below the stacks and in between the injectors, were normally my wire loom sits. There's just not enought room to properly get the lines in there. On top of that 3/8 lines don't give the short radius I would need so the tubes would have to come out on top, where they would be in the way for the linkage and other stuff that's up there.

To reinforce a similar plate I would place angular ss pieces along the lines created by the bolts. The angular piece would create a triangle with the plate itself so it would be reinforced substantially. I can wel those on.

Would be that some fuel is entering the chamber althought the holes sit a lot higher than the injector. Originally the were right below the injectors, which I plugged with JB weld. (I also contoured the runners with the JB WELD stuff to fit the head perfectly but it was already bulging, so it was a good thing I took the manifold off).

I'm not so much in favor of welding as I'm afraid the manifold would warp.

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Re: puff of blue smoke at higher rpm decel

Post by Belgian1979 » Tue Feb 06, 2018 4:04 am

Newold1 wrote:
Mon Feb 05, 2018 5:10 pm
I am guessing you don't have a welder available who can tig a thicker plate for you?

I also think there might be another problem with that vacuum plenum in that it may be filling somewhat with gasoline vapor and possibly a small amount of fuel and that mixture is lighting off in that chamber and creating a pretty strong explosion in that plenum that did the blast forming? That area is pretty big in volume and I am thinking it might be possible?
Could be although the traces on the plate suggest a spit back, which happens but not often.

To combat this I was also thinking of a screw in check valve but to withstand the forces it would need to be of copper or similar and small but still provide enough flow. Haven't found one that fits the bill.

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Re: puff of blue smoke at higher rpm decel

Post by mk e » Tue Feb 06, 2018 7:11 am

I wouldn't weld it either and I weld everything as a general rule. Guaranteed you'd need to recut the gasket surfaces before it would seal again.

Adding a frame is a fine plan. I would go carbon steel rather than SS as it's easier to work with and inside so rust is not a concern. SS would work just fine too though.

Fittings can take very little room, a 1/8"npt street elbow would be about 1/2" tall, 1/16" street elbow maybe 3/8"tall and fine for MAP but maybe not enough flow for your iac.
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Re: puff of blue smoke at higher rpm decel

Post by Belgian1979 » Tue Feb 06, 2018 9:17 am

Mark, I've been trying several places, but those that have enough room to accomodate a 90° fitting are obstructed by the mentioned parts. The places that are not, do not have the room to screw in such a fitting on average.

As for the deformation : I went out and bought a SS plate today (4mm/0.18"). The weight is remarkably heavier than the one that cam out although thicker. I assume the plate is therefor made from alu and not SS as I first thought.
Now for the caveat with this : I think the bulging is therefor not caused by blow back or by a fuel explosion but by the expansion of the alu plate which seems to be higher than the sideways expansion of the manifold. This will explain the rupture of the silicone as well.

This then begs the question if a plate in ss would be better in terms of thermal expansion.

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Re: puff of blue smoke at higher rpm decel

Post by MadBill » Tue Feb 06, 2018 9:25 am

The temperature would be very similar between the plate and the manifold; there really couldn't be enough difference to cause such distortion.
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Re: puff of blue smoke at higher rpm decel

Post by mk e » Tue Feb 06, 2018 10:33 am

MadBill wrote:
Tue Feb 06, 2018 9:25 am
The temperature would be very similar between the plate and the manifold; there really couldn't be enough difference to cause such distortion.
Right, and they are both aluminum so have the same thermal expansion rates, that can't be the issue now but could be once the plate is replaced with SS...SS has about 1/2 the expansion rate so it won't buckle but might break the seal.
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Re: puff of blue smoke at higher rpm decel

Post by Belgian1979 » Tue Feb 06, 2018 10:47 am

MadBill wrote:
Tue Feb 06, 2018 9:25 am
The temperature would be very similar between the plate and the manifold; there really couldn't be enough difference to cause such distortion.
I understand, but on the other hand an explosion (unless unburnt fuel in the vacuum chamber) would damage the throttle plates first before buckling the plate. I can hardly image any unburnt fuel running upstream from the injectors, especially with the inclination the runners have in this case.

Then there is also the rubber hoses connecting to the chamber. Those would burst first I think.

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Re: puff of blue smoke at higher rpm decel

Post by Belgian1979 » Tue Feb 06, 2018 11:09 am

FYI
Image
Image

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Re: puff of blue smoke at higher rpm decel

Post by MadBill » Tue Feb 06, 2018 12:09 pm

However unlikely the possibility (Have you experienced any substantial intake backfires?) it's hard to imagine that plate being distorted that way by anything but exploding mixture. One way to guard against same would be to fill the chamber with SS scrubbing pads https://www.google.ca/search?q=stainles ... 45&bih=863 They would serve as flame arrestors and prevent the igniton of a combustible mixture.
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