I searched and didn't see much on this topic.
Wrapping your headers to reduce engine heat. I've seen this in FI cars with the wraps on headers near turbos, but do you think there's any benefit to wrap in the VW engine with tins in place?
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The wrap will (of course) keep the heat in, but (on a street car) if it gets wet at all the wrap will take a long time to dry out and the extra heat and moisture can reduce a very nice (and expensive) header to rust VERY QUICKLY! I think you'd be further ahead looking at insulating the underside of the rear tinwork that's over the exhaust. Al
Some Subaru owners express concern about high engine room temps. To help lower those temps, headers are either ceramic-coated, wrapped, or both. Other mods, such as vents, louvers, hood offsets are used also.
Mine's a VW 1905cc. It doesn't have the cutout in front of the fan like a CMC should (my guess is the PO never removed it) but it is open to the ground in front of the fan area.
My car runs at a consistent high temp so I'm trying everything to reduce this to a much lower level. I'm not sure if I know enough about the vacuum and pressure on aerodynamics to fab up a ram air w/o running a front mount air inlet.
All my engines previously have been in the front!
Heat is both friend and enemy for our engines. We only use 1/3 of engine heat to produce power, with the rest either going out the exhaust, or being cooled by engine management, such as oil coolers, rads, etc.
Not sure what your setup is, but there are well-established means of lowering oil temps in a/c engines. Good engine tins and sealing are first priority, then an efficient oil cooler, preferably one with a fan and thermostat control. All our engines need lots of air. As we increase HP far beyond the parameters early 356 engineers contemplated, increasing waste engine heat becomes a factor. That's why so many of us spend lots of time scratching our heads.
I know I need to redo the rand around my tins bc of the foam deteriorating. I"m wondering since there are some gaps there that it may be sucking in all that exhaust heat. I'll tackle that first.
I've a oil cooler in the right wheel well that runs properly and the tune, while it isn't perfect , doesn't seem to be that out of wack. Being my 1st aircooled engine I'm probably doing something majorly wrong there but it runs strong 
So my thoughts are the primary cooling actions have been made.
Just looking for anything else I can do that I haven't done yet. It may also be that my calibration on the gauge is unhealthy...who knows.
Where is your oil temp sensor.
Timing can also affect temps as well as carbs not being synched.
I've thought about adding a heat shield between the headers and the tins surrounding the rear apron tin work. I have no heat issues so I've not tried it.
Post some photos of the engine bay. You mentioned there was gap in front of the engine. It'd be good to see how big of a gap it is and if it something that needs to be closed up.
I have a 1915cc and there is no hole cutout of the firewall in front of the fan shroud and mine does not run hot. You may want to check the timing if it hasn't been checked in a while. Mine had been running fine but it was warm. When I checked the timing it was off quite a bit from 32 degrees TDC.
Keying off on the question about where the oil temperature sender is. Where SHOULD it be? Perusing the net I find that there are several locations possible. Mine is currently mounted w/ the pressure idiot light sender at the engine bung just fwd of the distributor. Mounted with a T fitting. Hmmm . . . I see that one can mount the temp sender in the hole where the rear oil pressure relive valve/spring are housed. Remove the plug,, and replace with the VDO sender. OK, I like that one. Another idea is to tap into the oil circulation system of the pump or case somehow, and I do not understand this one. If one has a full flow oil filter (as do I, and most here I think) seems there would be opportunity to plumb a T into that line and get excellent flow over the sensor and a good signal. So what do all y'all who know for sure have to say about all of this??
And yes, a radiation shield inserted between the hot pipes and the std tins will reduce the heat transferred up into engine compartment. Also note that said std tins are in fact a radiation shield, and as such do a right good job blocking the radiation even so, as well as keeping convection (air currents) blocked. A second radiation shield will help, but it will not double the resistance to radiation heat transfer, I'd have to do the math, and what the surface is plays a big role. Heat reflective (i.e., shiny) will be best. There are special paints one can apply, but how they weather is a potential limit. And the color of the coating (white vs black, say) has little to do with the transfer/refelction of the radiating heat, as the heat transfer happens in the infrared (not visible) wavelengths.
El Frazoo out.
Oil temp sensor is on the underside of engine at drain/filter area.
I've a secondary trigger replacing the dipstick that is y'ed in to the same wire to trigger the green oil light.
Tins are black and chrome. Not a lot of room for pix but not entirely sure if every thing is there or not...
I bet my timing is jacked causing hotter temps
Engine tin helps to dissipate heat - hence desire for semi-flat black paint over chrome plating. Look at the CMC build manual that came with car or here in library (for donating members). CMC supplied a fiberglass panel that fit below the 2x2" rear tubing completely across back. There is another across back on top of same 2x2" bar - it gets fiberglassed to rear shell. That should completely seal off engine from exhaust.
WOLFGANG posted:CMC supplied a fiberglass panel that fit below the 2x2" rear tubing completely across back. There is another across back on top of same 2x2" bar
Yup, those are there. And all tins easily visible.
I just can't tell what's behind the engine by the firewall...almost impossible to see back there...I'm wondering if that is the source introducing excessive heat
I've got the actual build manual from CMC. There's not much to tell what was placed in by the PO as even tho the manual says to open the firewall in front of the fan, that wasn't cut and mine is still enclosed
You don't really have to worry about air coming in from the front; it's not introducing heat into the engine compartment, and any leaking air from around the front breastplate (on the bellhousing) or a hole in the front (front of the car ahead of the engine) firewall is actually beneficial and feeding the carburetors and fan/cooling system. Most of these cars benefit from a hole in the firewall; if you look at the engine compartment closely there isn't enough fresh air intake for long engine life without it.
If you are fortunate enough that your car has positive air pressure in the engine compartment at speed, the air moving through the engine compartment (and out the engine lid grille) will be removing the heat radiating from the engine surfaces, so it's not re-ingested by the fan and carburetors. You'll know it's right when a remote air temperature taking thingie (I'm having a brain fart at the moment!) mounted on the fan shroud reads the same as (or just a few degrees above) the temp outside.
Remember, these things are air (and oil) cooled, and the more air you can feed it (and the cooler it is) the longer your engine will live and the more power it will make over it's operating parameters. Al
Kelly, Bruce did some extensive testing on the subject document oil temps from senders he set in various locations on the block. There can be as much as 20* difference in some cases.
Tapping the case near the dip stick was the most accurate if I recall.
https://www.speedsterowners.com...nometer-test-results
Yup...Near the dip stick turned out to be the most suitable location. In my case (I have a universal case) I drilled and tapped the block-off plate that covers the hole that would be used for a type 3 dip stick. Previously, I had it in the side of the "add-on" sump. There, it measures the temp of the oil right after it has been thru the engine. That was a little scary. As high as 250 F and it varied as much a 50 F depending on how much air was flowing over the sump (Read car speed here) Typically, now, I get 179F to 190F and that's in the Summer here in So Cal.
I have the stock cooler and a 72 sq" remote with fan in the left rear wheel well. I use a 180F thermostat sw for the fan and a MoCAL oil bypass sandwich on the remote filter. One of the most surprising discoveries of all my fooling around with testing the engine oil temps is what the stock oil cooler does. I actually drilled-welded-tapped ports in the oil cooler adapter (doghouse cooler) and installed two Dakota Digital senders in the inlet and outlet passages. That cooler only drops the temperature of the oil 4 degrees F !! The remote drops the temperature about 20 F between the inlet and outlet. Between the two, they do a pretty good job if the engine compartment is really sealed up well so that the only way Air gets in is thru the hood grill. I have a VS and it came with the hole in the firewall in front of the fan but I blocked it off. It wasn't needed. I have a 2110 and the cyl head temp has been consistently around 350F.
I did find, using a manometer, that there is a slight negative pressure (1"H2O)in the engine compartment at Fwy speeds. This tells me that the grill in the hood is slightly inadequate. Actually, the grille isn't at fault but the size of the two final openings into the engine compartment on either side under the grille are. Their aggregate open area is 50% LESS than the grill opening area. Rusty Smith solved this by installing a cool looking screen in that "rain baffle" under the grill. I cut out just enough of the baffle on both sides to eliminate the 1" H2O vacuum at fwy speeds. I'm too scared to see if it's still there at say...100mph on the fwy
Anyway...the bottom line is to seal up that engine compartment all the way like the original VW's and Speedsters and then get cool outside air in there by any method you deem suitable..... I hope this helps. I had fun tonight looking over my older posts on this subject.....Cheers.......Bruce
Bruce- Could you post the links to those threads?
Thank you sir.
It's a great read and I thank Bruce for all the time he put into this.
