What's new

to paint or not to paint

delbertinie

Member
on a air cooled motor does it makes it run hotter with a coat of paint on it.


I painted the case and I am waiting for the jugs to arrive and the heads to be finished at the machine shop.

Just had a thought that the paint might insulate the motor enough to raise the temp.

Can anybody else shed some light on my cloudy mind


off topic

has anybody heard of a piston sleeve kit from aa performance.
are they good parts.
 
Last edited:

ydeardorff

New member
As far as I know, so long as you don't paint the cooling fins you should be fine. But using the right paint is important, not only from a heat stand point, but also from an oil one too. Hot oil will destroy paint very fast!
i repainted all the tins on my 66 beetle I had back in '96. Once the doughnut seals failed under the oil cooler, I had to completely start over. It looked great for about 2 days. *laugh*
 
Last edited:

tgidavid

New member
Not enough to cause issues. If paint was an issue, then radiators would be melting off the endtanks. I would run the engine a few cycles to burn off the protective oil then spray it. Personally I like the look of the edge of the fins painted and the space between the fins left alone.
 

delbertinie

Member
I wiped with reducer, wire wheeled it ,used reducer again. Then used wax and grease remover ran over it with a propane torch wiped it down again with reducer and wax and grease remover. primed and painted it with a 2k catalyzed primer and paint that has a heat additive.
brake fluid does not bother this paint. I.C.I. paint

No I just wondered if air cooled engines where diff. from water cooled.

I wanted to paint the case and heads silver the jugs and the push rod tubes bright red and leave the cooling tins black.

Going for the red baron snoopy look *thumbs up**yipes*
 
Last edited:

letterman7

Honorary Admin
Heads and jugs should be left either unpainted or a flat black for best heat dispersion. Harley motors are in the open air with almost constant airflow - these motors aren't. Paint the block, leave the rest alone. Purchase anodized push-rod tubes if you want some color there.
 

tgidavid

New member
Heads and jugs should be left either unpainted or a flat black for best heat dispersion. Harley motors are in the open air with almost constant airflow - these motors aren't. Paint the block, leave the rest alone. Purchase anodized push-rod tubes if you want some color there.

I respectfully disagree. The fan connected to the alternator/generator is always pushing air even when idling and , if i recall correctly, is most efficient in the 2500RPM-3300 rpm range. The porsche style fan arguable is even more efficient. The engine tins help divert air evenly across all cylinders. V-twin bikes don't usually overheat in traffic because in most states, they can share the lane and avert any issues with still air.
 

delbertinie

Member
do you think if i clear coated the fins on the jugs it would build up heat. just leave them natural with a layer of clear. either that or flat black them

what would be the big stink about painting the tubes do they transfer that much heat out of the motor-confused*
 
Last edited:

letterman7

Honorary Admin
I respectfully disagree. The fan connected to the alternator/generator is always pushing air even when idling and , if i recall correctly, is most efficient in the 2500RPM-3300 rpm range. The porsche style fan arguable is even more efficient. The engine tins help divert air evenly across all cylinders. V-twin bikes don't usually overheat in traffic because in most states, they can share the lane and avert any issues with still air.

Yes, that's true (in respect to the VW fan). But you're comparing a V twin with a huge cross section of fin area to a VW jug that's smaller and needs to be force-fed airflow. Jake Raby had a great article on his site about factory airflow versus his DTM shroud :http://www.aircooledtechnology.com/type1/dtm/part2.htm and http://www.aircooledtechnology.com/type1/dtm/index.htm#results which in part explains how the airflow in a stock system works versus what he developed to improve the flow. And here is the effects of a 911 style fan on a T1 engine: http://www.aircooledtechnology.com/cooling/faq/answers.shtml
Good reading - the guy has been doing this for quite a while.


In any case, jugs should never be painted or if they are, painted flat black. Polishing the edges is fine, but if you have all the tins in place (and you should) you won't see them anyway, so what's the point? Paint the tins (again, satin or flat black is preferable) and be happy. The engines didn't come painted with anything other than black from the factory for a reason - heat dispersion. Don't use gloss paints except for the fan cover and never use a VHT paint. Painting the pushrod tubes is fine, though any oil leaks may negate that effort.
 

delbertinie

Member
again I ask does anybody now how much cfm a stock system delivers at its most efficient rpm range

cfm is a coefficient that I can wrap my brain around.
 

delbertinie

Member
Interesting reading, thought about adding an electric fan to continue cooling once the the motor is shut off. On a timer for another ten to 15 minutes. You and I both know that motor temp climbs after shutdown dramatically.

my thoughts are that heat plus contraction and expansion is what kills a motor. So when a motor shuts down the temp spikes then drops off.
 
Last edited:

ydeardorff

New member
Similar in thought to a turbo timer huh?

Might be a good idea so long as it doesn't hinder the fans operation or airflow while in use.
 

delbertinie

Member
the one thing about us ...........all of us.........here.............is we get a kick out of reinventing the wheel or else we would drive the same cookie cutters as every other dick and jane*thumbs up**insane**love it*
 

letterman7

Honorary Admin
Because an electric fan can generate volume but not a lot of pressure. You'd need a squirrel cage fan the size of the VW unit with the appropriate ducting to produce the same cooling capacity - the fans that you'll see advertised to place over each bank of cylinders is for drag use only - where the motor only needs to be cooled at the end of the race when the car is being pulled (or driven) back to the pits at a low speed.
 

delbertinie

Member
Because an electric fan can generate volume but not a lot of pressure. You'd need a squirrel cage fan the size of the VW unit with the appropriate ducting to produce the same cooling capacity - the fans that you'll see advertised to place over each bank of cylinders is for drag use only - where the motor only needs to be cooled at the end of the race when the car is being pulled (or driven) back to the pits at a low speed.

again not gonna modify my stock setup but how would one measure pressure.

On my car at idle or even at higher revs it does not have that much pressure at the bottom of the cylinders I stuck my hands in the lower cavities under the cylinders it felt like a house fan on the lowest setting

i even capped the heater hoses off to see if i could create more flow didn't seem to make any diff.
Also tighten the fan belt no noticeable diff. either*idea didn't work*

in fact was really hot at the third cylinder but much air movement.

and as far as the drag car setup i have not found one to look at yet.
 
Last edited:

letterman7

Honorary Admin
That's a subject best left to an aeronautical engineer. The flow to the outside of the cylinders where you're feeling it differs from the pressures generated within the fan shroud, and that all correlates to the internal veining in the shroud directing airflow. You can feel the pressure differential at the fan - put your hand just to the edge of the opening on the outside (for God's sake don't put your fingers in the inlet) and you'll feel the pressure and airflow with the engine running. It's quite the amazing piece of engineering for it's day!
 

delbertinie

Member
it felt almost the same at the inlet as it does the exit nominal

i must have something wrong with mine that may be the ultimate cause of this premature rebuild.
i wish i had another one guage the diff or if they are the same flow
 
Last edited:
Top