engine and drivetrain Heat shield for DCOE Webers

[GazM3]

Hey there.  

 

I was thinking about forming up a heat shield for some separation of air from the hot side of the engine so it can draw cold air from behind the light etc.  

 

i done a quick Google image  search on this and could not find any example of one on any model using dcoe carbs let alone the Bmw 2002.  

 

Does this not happen due to the fact there is no maf with temp sensor inside?   I would have thought due to the light weight and modest power even a small gain in drawing the coldest air possible without any weight penalty would be worthwhile.  

 

There te are a few blank plenums kicking around on the net but they would effectively dilute the spectacular intake noise of the doce carbs.  

 

Thoughts?

[visionaut]

FWIW, Weber does make a heat shield for DCOEs (its fitted to the bottoms).  But they're rarely fitted with an M10 set-up, as they were designed for Weber applications on other motors where the carbs sit right over the exhaust (both same side of engine), not for a straight flow-through set-up.

 

If you want coolest intake air temps, run an airbox.  For all the effort required to fully try to 'keep the hot side hot and the cool side cool' on an M10 in an 02 engine bay, it might only be marginally better than nothing there at all (I doubt there's much steady cross-engine airflow), and it still won't work as well as an airbox.

 

You also have to be careful trying to direct or feed a hi-flow airstream directly toward/past the DCOEs, lest you mess with intra-/inter- carb throat flow variances (I know it can mess up flow especially at the #1 cylinder). I guess you could try fabbing up something to try to improve it, but the carbs side of the 02 engine bay already seems to draw ambient outside air in pretty nicely through the grilles and from below the car while driving.

[zinz]

we chatted about this race car's setup in Beauty Shots, last week... interesting cool air duct, sans box.  I mentioned disturbed air flow, but this is apparently not an issue for this car.

 

Very cool  and simple setup, though

 

 

Ed

 

 

[TobyB]

yeah, you have to be very careful creating a tuned airbox in front of dcoes.

 

They work partly by spitting fuel back OUT, so anything you do tends to mess with them in odd ways.

I had a very pretty airbox that netted me 1.5 seconds a lap when I took it OFF and ran with open trumpets...

 

'DCOE airbox' as a search string nets you hundreds of images, many from right here on the FAQ...

 

t

[GazM3]

Cheers guys.  

A heat shield would be easy for me to fabricate.   Seperating basically from the radiator back to the start of the trumpets with a rubber seal to the underside of the hood is what I'm looking at

[TobyB]

That's probably a pretty good idea- just make sure it doesn't get too restricted at the inlet. 

Grabbing the whole headlight area is probably good enough.

You have the added 'advantage' of not having the brakes or steering in your way over there. 

 

Carbs DO like a nice, cool morning, so getting more of that cool morning to them can't hurt.

 

t

 

[GazM3]

Yes being RHD and dual low sitting boosters make a nice opputinity to make an effective heat shield.   I'll make a template first out of 5mm thick waxed cardboard (corflute) material and line it with medium temperature silver foil tape.  It will keep it light.  I can use large rivets or the adhesive tape to hold it all together.  

 

Perhaps if I'm happy with it and it performs well may line the hot side with blingy gold foil adhesive heat shield material.  

[Chris_B]

You may be wasting your time on this. That side of the 02 is pretty open, and it seems like a fair amount of outside air would be forced up into the area of the carb air intake when the car is moving. There is no doubt that having cooler (more dense) air at the carb intake will produce more power, but without a temp comparison of the actual and potential intake points, you won't know.

[andreb]

The OE set up on a real Ti had an airbox that directed filtered air into each carb and picked up from the fresh air inlet located on the left/top of the rad. Those were Solex carbs (right?) though and Weber's are a bit more finicky. There are "fresh air" boxes for DCOE's but be careful to not create any ram-air affect. I would say all the time and effort would be worth little gain, we never ran anything like this on any race motor. The engine compartment on the 02 stays pretty cool like to the OP said. Plus, IMO part of the fun of having side drafts with open bells is the clattering, bug sucking whoosh at WOT. Air box dampen all that fun!

[GazM3]

I don't want to put an airbox/plenum just a heat shield.  

 

I guess it's on the cold side of the engine so any gains may be minor.    Even if I can get 10degC drop its worthwhile.  I guess most gains will be on the road in traffic keeping the intake as cold as possible. I'm thinking more in terms of less losses in traffic rather than outright gains.  

[downhillwolf]

Anyhow, any filter system (that I'm avare of) on DCOE's have a tendency to bring hot air down the throats...
I have Alpina version of ti airfilter, with bigger filters and after a uphill run in summer and airfilter housing gets hot to about 40-45 degrees celsious with outside air at 28 celsious. I have rear mounted baterry, open battery cutout and top cutout and this still happens. So kind of good and stealth heat shiled would be fine but probalbly hard to produce.

 

[KFunk]

On my truck the intake manifold is bolted directly to the exhaust manifold, and it still runs fine except for occasional vapor lock on real hot days, hah.

 

(example pic, mine isn't that shiny.)

[downhillwolf]

Wondering about 4 years long challenge to bring cold air to webers... The plan was to get airfilter behind the grill and throght tube then deliver cold air, but this fall apart how to keep original looks of the BMW-Alpina beauty.
There were some atempts(theoretical) how to manage good looks and usefullness...
So had a lot of ideas and a steering box to tighten, so when car was "apart" cardboard and a loot of brainstorming and options. Probably used a ton of tape and cardboard, garage was a mess.

The main concerns were about how every line(booster, brake, electric...) should go. Had a ton of options, but one prevailed.

Now finally this thing is made out of plastic, but not tested jet :/
But after so much thinking about air flow and everything else this is a small peek...
What do you think?

[GazM3]

Nice one.  

 

Im thinking of doing similar but continuing the heat shield to link up with the weber trumpets.   Ill have my car back from the mechanics very soon then I can start working on heat shield.   

 

The battery is directly in the path of the ideal cold air pickup point.  I may in the future relocate the battery to the trunk with one of those upgraded stress braces.  

[downhillwolf]

14 hours ago, GazM3 said:

Nice one.  

 

Im thinking of doing similar but continuing the heat shield to link up with the weber trumpets.   Ill have my car back from the mechanics very soon then I can start working on heat shield.   

 

The battery is directly in the path of the ideal cold air pickup point.  I may in the future relocate the battery to the trunk with one of those upgraded stress braces.  

Had same idea but, if you make a little calculations, cold air way more important than heat shielding carbs.