Ceramic coat vs foil for heat reflection?

[Seymour Snerd]

If I could I would but I can't so I shan't

OK, then here's my final offer: DCOE webers a la GS Corvette and Lamborghini. After all, who wants to look at an ugly old four barrel. Might as well paint the window. :shocked:

 

[Alex]

OK, then here's my final offer: cross-ram webers a la GS Corvette. After all, who wants to look at an ugly old four barrel. Might as well paint the window. :shocked:

Or, do what Lamborghini did with the front engine cars (and the early Countachs) when there was a clearance problem: DCOE webers.

Noooooo, 1 carb is problem enough to get tuned perfectly ......... any more, forget that!

I present you my solution

It fits, rear clip opens perfectly w/o interferences. I <3 it. Now i Just need to figure out how to get the filter to it.

 

[Seymour Snerd]

OK, now rotate it 180 degrees....

 

[Alex]

OK, now rotate it 180 degrees....

.... and be unable to open the rear clip, lol =)

I could rotate it 90* BUT I'd still need to filter it and I'm out of ideas how to do that, lol.

 

[Alex]

It fits!

It was touch and go for a little bit because I'm working with +/- 1/4'' tolerance basically (Around braded hose, the body, etc.. etc..), but it fits.

Now I just have to do the air box and get a nicely designed carbon fiber air intake for it

 

[Seymour Snerd]

It fits!

It was touch and go for a little bit because I'm working with +/- 1/4'' tolerance basically (Around braded hose, the body, etc.. etc..), but it fits.

Cool! You know you haven't done your job unless there are some parts that just barely avoid touching and thus are always at risk for causing the car to self-destruct. That's called "fully optimized space utilization."

 

[Alex]

Yep yep.

If I get a nice day I plan on taking the intake and swapping it onto my cobra (which is using a drop dish + 14x3 round + extreme top) and do some driving/data logging - I'm hoping I see no difference in the a/f or anything unusual (e.g., surging, stumbling, etc...).

Not many people use blow-through carb hats in a n/a application, however the EV pro hat seems to the best of the best (e.g., 6'' tall so the air has plenty of time to smooth out over the bleeds)

 

[Cliff Beer]

Alex, if you don't mind me saying it, I think you're over thinking it on this one. All you need is a decent filtration system with some reasonable surface area. You don't need a 4" diameter pipe without twisties or lesser radius. In other words, it's OK if the inlet pipe to the carb takes a hard turn or two or is a somewhat convoluted shape to clear the rear deck. And, the ram effect of a scoop (if that's something you were wanting to engineer) won't add anything. I recall seeing some test data of an engine being fed with a stock under-hood induction system and the same engine with a cold air hood scoop - even at speeds of over 100mph there was absolutely no ram effect (air doesn't compress that easily...) and the differece in intake temps wasn't that great (~25 degrees F.) which had a very nominal effect on power output. For normally aspirated engines this is generally the case (not so however with turbocharged engines where inlet temps ahead of the turbo do indeed make a big difference in power output).

Frankly, if I was you I'd a) look for, and use, a low profile manifold (dual plane is going to be quite tall, for example) just to get as much clearance as possible, and b) lay up a custom inlet tube in fiberglass which conforms to the shape of the back deck and gets its air from somewhere in the engine bay that is as far away from the headers as possible and ideally near an inlet in the bodywork. Get some large blocks of foam (4' by 4' is good) and just shape it how you want and lay up the fiberglass over that.

Good luck and persist!

ps. if you want to insulate against heat (radiant and conductive) the absolute best material is foil over asbestos. I have some of that stuff - aluminum foil over 1/8th inch asbestos - and it can be shaped and contoured (if done gently) to whatever surface shape you're working with. It is shockingly effective. Might want to put on a mask when cutting it with the old band saw.....

 

[Alex]

Alex, if you don't mind me saying it, I think you're over thinking it on this one. All you need is a decent filtration system with some reasonable surface area. You don't need a 4" diameter pipe without twisties or lesser radius. In other words, it's OK if the inlet pipe to the carb takes a hard turn or two or is a somewhat convoluted shape to clear the rear deck. And, the ram effect of a scoop (if that's something you were wanting to engineer) won't add anything. I recall seeing some test data of an engine being fed with a stock under-hood induction system and the same engine with a cold air hood scoop - even at speeds of over 100mph there was absolutely no ram effect (air doesn't compress that easily...) and the differece in intake temps wasn't that great (~25 degrees F.) which had a very nominal effect on power output. For normally aspirated engines this is generally the case (not so however with turbocharged engines where inlet temps ahead of the turbo do indeed make a big difference in power output).

Frankly, if I was you I'd a) look for, and use, a low profile manifold (dual plane is going to be quite tall, for example) just to get as much clearance as possible, and b) lay up a custom inlet tube in fiberglass which conforms to the shape of the back deck and gets its air from somewhere in the engine bay that is as far away from the headers as possible and ideally near an inlet in the bodywork. Get some large blocks of foam (4' by 4' is good) and just shape it how you want and lay up the fiberglass over that.

Good luck and persist!

ps. if you want to insulate against heat (radiant and conductive) the absolute best material is foil over asbestos. I have some of that stuff - aluminum foil over 1/8th inch asbestos - and it can be shaped and contoured (if done gently) to whatever surface shape you're working with. It is shockingly effective. Might want to put on a mask when cutting it with the old band saw.....

I think I'll pass on the asbestos =)

I understand where you're coming from, but at the same point in time I have to disagree to some extent - when searching around for filtration ideas, I came across several I thought had promise, but after reviewing the followup results, found out it was a horrible idea (e.g., causing massive changes +/- 2pts in air/fuel by using/removing the filtration method)

I've also learned just how finicky a carb is - for example, I thought as long as you had some clearance over the vent tubes, you're fine (hence why a low profile carb plenum might work) .. not so; you want around 1.5+'' above the vent tubes in order for the air to straighten out and flow over it and the bleeds properly.

Anyways, can't get a lower profile manifold (I'm stuck using a gmpp lsx tall deck one, unless I want to make a custom sheetmetal manifold, which would probably be a really bad idea in this application), and definately can't route tubing to the side vents - I've studied Cam's setup and on my plastic LS1 block I can see how to do it. However, on my RHS w/ massive all pro heads, ain't going to happen unless the tubing goes from like 4'' OD to 2.5''OD and back to 4'' (which would be a pretty bad move obviously)

 

[Jim Cowden]

Why not make a duct come tray out of alloy sheet and use the rear window as the lid.
So you have an alloy tray with a large seal on the top that seals on the underside of the window.
You can use K & N foam to put the filter in a position that suits.

The pic is the one I made for my car it runs a clear lid, but lets say it was taller and sealed on the window when the clip was put down.

If you are worried about heat cover it in turbo blanket or similar on the outside.
IMO the hose and 90 deg hat thing looks pretty ordinary.

Jim

 

[Alex]

Why not make a duct come tray out of alloy sheet and use the rear window as the lid.
So you have an alloy tray with a large seal on the top that seals on the underside of the window.
You can use K & N foam to put the filter in a position that suits.

In order for that idea to work I'd need a filter than is, approximately, 18''x12'', and it to be situated ~4'' above the carb - that would make designing a rear scoop virtually impossible (at least now it just needs to bubble in the middle of it)

My filter dimensions are roughly constrained by needing at least 1200cfm flow through a filter, and if you look at the above picture of my rough layout, you can see I'm really constrained in what I can do, filter properly, and have adequate flow.

 

[Jim Cowden]

Who said it has to be above the barb you need to think outside the square when you have space restrictions, Put the filter all the way down floor or sides of the tray as per the pic.

The tray starts at the carby area with a seal to the window it can run down the inside of the window to the rear, you could tear drop it as it travels down the window and put the hose and filter on the end were it is not seen if that suits you.
OR just run it down the inside of the window and have the filter in the side or floor of the tray as per pic.

Or a tray goes under the carby it seals on the window the tray drops down into the massive void of space at the rear of the intake manifold ,the filter is mounted into a sheet alloy box, use the foam or panel filters, bring a duct in for cold air.

You are stuck with the materials you have chosen ,I would look at sheet alloy ,if you want the trick more modern look get it covered in carbon adhesive.

People look in that window I would do something special but not complex

I think the bend out of the carby is setting the layout for your design.
You change that via a tray or whatever and you can the change the rest of the layout.

Also I would think a filter area of say 3 times the entry of the carby would be more than enough. the large it is the less you have to clean it.

Jim

 

[Alex]

Who said it has to be above the barb you need to think outside the square when you have space restrictions, Put the filter all the way down floor or sides of the tray as per the pic.

The tray starts at the carby area with a seal to the window it can run down the inside of the window to the rear, you could tear drop it as it travels down the window and put the hose and filter on the end were it is not seen if that suits you.
OR just run it down the inside of the window and have the filter in the side or floor of the tray as per pic.

Or a tray goes under the carby it seals on the window the tray drops down into the massive void of space at the rear of the intake manifold ,the filter is mounted into a sheet alloy box, use the foam or panel filters, bring a duct in for cold air.

You are stuck with the materials you have chosen ,I would look at sheet alloy ,if you want the trick more modern look get it covered in carbon adhesive.

People look in that window I would do something special but not complex

I think the bend out of the carby is setting the layout for your design.
You change that via a tray or whatever and you can the change the rest of the layout.

Also I would think a filter area of say 3 times the entry of the carby would be more than enough. the large it is the less you have to clean it.

Jim

All good ideas, but I'm liking my nice, simple setup, hehe (plus you won't see it once my carbon fiber racing scoop is built and in place). Plus, unfortunately as I've learned, you don't want to think too far outside the box with air filtration and a carb - I've had enough chats w/ experts like Braswell to know just enough about stuff like what can weaken signal strength to be dangerous, lol.

The good news is I borrowed the setup from the superlite and stuck it on my cobra. Right now my cobra (408w, 4150 Holley 850cfm) uses a drop dish with a 14x3 + xtreme top lid. I wanted to try out this setup to see if anything unusual happened (e.g., loss of signal strength or stumbling or something unusual due to air not having enough time to smooth out over the bleeds). It went better than expected - my LM2 wideband showed no abnormal changes in a/f, everything (throttle, etc..) was crisp and clean. Actually, truth be told, I thought this setup was a little bit more responsive than the 14x3 I'm using. (despite the fact I was lazy and hung the filter directly over my headers - now THAT's a heat soaker, lol).

If the extra responsiveness isn't in my head, I'd hypothesize that the extra 2'' above the vents i have may be making a bit of difference (more time for air to smooth - when I was speaking to Gordon (he makes the ev pro hats) he explained why this would work perfectly in my n/a setup - how it smooths the air nicely before it hits the bleeds).

Also, as an fyi, here's how you size air filter:

Engine cfm = CID x Maximum RPM / 20839 (assuming n/a)
Round filter cfm: Diameter x Height x 6 x 3.14
Flat filter cfm: Length x Width x 6
Tapered filter cfm: ((Top OD + Bottom OD)/2 ) x Length x 6 x 3.14

You can match them, but it'd be better to upsize the filter cfm, especially w/ more bends (the more bends the more cfm you should have in your filter)

Jr. Air Engineer at work, lol :idea:

 

[Alex]

I think I have my final setup

Need to powdercoat the box and then cover the outside w/ reflective foil, but this gives me the proper sized filtration, minimal bends, reflects radiant heat away (headers/transaxle) and will ram cold air at speed into the box.