CENTERMOUNT FAN SHROUD DUCTING INSERT

[Piledriver]

Bumping a great idea

[58Dub]

anything new on this??

[FJCamper]

Hi Stripped66,

We have the prototype center-mount housing on a 1600 now for road testing, and a 36hp insert plotted in the CNC machine for cutting.

The test parameters for the centermount housing is in a 1600 street Ghia, stock engine compartment sealed as factory spec. None of our racing venting, air ducting to fan housing, etc.

We've just gotten this street Ghia, a '72, and it is to remain a daily driver.

FJC

[Ukhozi]

Great minds think alike even when separated by the Atlantic.
I have a highly tuned 1641cc T1 in an Eagle kit car, (Cimbria to the USA guys). http://ukhozi.page.tl

Due to the high ambient temperatures (36C plus) and very possible traffic snarl ups with summer tourist, I have been trying to improve the air cooling on my center shroud and tossing around many ideas from multi-stage electric powered 1500CFM fans, Porsche type fan, electric fan assisted OEM fan, and I finally after a lot of negative feedback from people who 'think' it wouldn't work, but never tried it, I was thinking of adding internal vanes to the center shroud as it was obvious to me that the internal 'flow' would be crap in an empty space with just the top and bottom 'V's in place but by using alloy vanes 'Lumiwelded' in place I could direct flow to where it should be as in an OEM shroud (didn't even think of the porker one) and then our Stirling forum master Rick, pointed me in this direction.

Would the insert be as effective or more so than adding internal shapes and if so when and how much?

Peter

Estepona, Spain.

[farmer]

Great minds think alike even when separated by the Atlantic.
I have a highly tuned 1641cc T1 in an Eagle kit car, (Cimbria to the USA guys). http://ukhozi.page.tl

Due to the high ambient temperatures (36C plus) and very possible traffic snarl ups with summer tourist, I have been trying to improve the air cooling on my center shroud and tossing around many ideas from multi-stage electric powered 1500CFM fans, Porsche type fan, electric fan assisted OEM fan, and I finally after a lot of negative feedback from people who 'think' it wouldn't work, but never tried it, I was thinking of adding internal vanes to the center shroud as it was obvious to me that the internal 'flow' would be crap in an empty space with just the top and bottom 'V's in place but by using alloy vanes 'Lumiwelded' in place I could direct flow to where it should be as in an OEM shroud (didn't even think of the porker one) and then our Stirling forum master Rick, pointed me in this direction.

Would the insert be as effective or more so than adding internal shapes and if so when and how much?

Peter

Estepona, Spain.

Why not just install a Puma Shroud with a venturi ring ? That is THE best cooling you can get for a dual purpose type 1. The only one that beats it (that I have seen) is a DTM shroud. They are getting quite expensive though.

T

[Slow 1200]

what farmer said....plus being a kit car, sealing the engine bay can be challenging to say the least, make sure that's sorted out first thing, plus it's a lot cheaper than reinventing the wheel

[FJCamper]

Gentlemen,

Our hopes for the centermount fan insert is that it optimizes (evens out) side to side airflow and ducts it to the factory cylinder shroud deflectors for the best possible aimed delivery using a single-plane housing.

In short, something better than stock factory. We're not challenging the DTM, which looks like a really nice piece of work.

Our street Ghia will have a properly-sealed engine compartment and we'll compare OEM doghouse, an aftermarket 36hp style housing, and our centermount hybrid for efficency.

FJC

[Ukhozi]

The 'Puma' shroud is just pain ugly and again with oil cooler. The DTM shroud looks great but useless if you have a remote oil cooler like my Dynaflow one, also on our kit cars we do not have sealed engine bays but complexly open with a lot of through air flow from under the car and from rear wing scoops, firewall is louvered so not so much a 'fire' wall as a decorative gearbox hider.

[Lo Cash John]

Seems like that upwards airflow into the engine compartment is a MAJOR problem. You said there's a lot of airflow from under the car up into the engine compartment. The problem I see is that airflow is carrying all the HOT air from around the header and that's already flowed across the cylinders and heads and leading it into the engine compartment and into the fan. Not this hot air blows down through the engine tins, across the hot engine and out the bottom. From there it blows up into the engine compartment, through the fan and across the hot parts of the motor. Repeat. Repeat. Repeat.

I think with some work, if you'd segregate the incoming cold air from the hot waste air, you'll see a DRAMATIC decrease in engine temperatures.

[Piledriver]

The other way of keeping hot/cold separation is a duct to draw the cold air in in a controlled manner... up is usually a good place.

I'm trying to get my son to do that on his buggy if only to keep the garbage out of the fan.
(sticks/grass etc from running off road)

[Max Welton]

Yep, like the type-3 and type-4 cars.

Max

[Marc]

I just put ~3000 miles on my trike, which has a center-mount shroud with no vanes. I used a "Super Beetle" fan since I was concerned about adequate cooling headed into 100° weather in the midwest. Even at 75-80MPH my cylinder head temp rarely exceeded 160°F or so (highest I ever saw was 185° after a long pull up a 9,000+ foot high mountain). J-type digital gauge with the sender under #4 spark plug, extremely accurate compared to the ubiquitous VDO CHT gauge. I don't have a sender on the right head so can't say what its temp was, but presumably it's even cooler - perhaps even too cool for the NGK B6HS plugs I'm running. Case/oil temp (thermocouple probe inserted in dipstick tube) was typically 185-205° under the same conditions. I don't travel light, with me on board the rig scaled out at almost a ton, and the huge tailbox is like dragging a parachute, so my li'l 1600 was working pretty hard....about 26-28MPG overall.

My conclusion is that (at least with the wide fan) there's more than enough pressure inside the shroud to provide adequate head cooling for a mild motor...not to say that the vanes shouldn't improve distribution, and I'd still like to add them when I put in a 2-liter for next year's run to Sturgis.

[Lo Cash John]

Marc, can you explain why your oil temps are higher than your head temps? I'm very much doubting the accuracy of your head temp readings. Something does not jive with those numbers. Have you verified the accuracy of the gauge and sender?

[Marc]

Yes, I have confirmed those numbers. Senders were tested in icewater and boiling water, read exactly 32° and 212° F respectively.

You can rest your hand comfortably against the head fins (about 140° is the pain threshold for most folks) until the engine's warmed up for about 10 minutes. At IDLE, in stop-and-go traffic, the head temp does sometimes run higher than the crankcase, but at 3-4000 RPM that's seldom the case. Certainly I'd expect higher head temps on a higher-performance engine, but this is a bone-stock (other than carb & exhaust) ~7.4:1 `74 1600DP. I'm using an in-and-out filter pump w/oversize gears and the oil pressure is somewhat high, which I suspect is causing the cooler to be bypassed more than ideal - with normal oil pressure the oil/crankcase temp would likely be lower, but I flogged the hell out of this engine climbing the Continental Divide and since then I can hear the death-rattle of loose main bearings, so as long as the temp is <210° I'll leave the pressure up where it is until I build another engine.

BTW, it's the same gauge with a selector switch to choose which sensor is online.

[Piledriver]

Oil temp and CHT are loosely correlated at best. CHT is ~load, oil temps are more RPM related.

He doesn't have a huge load on the motor despite the non-aero setup,(low frontal area) but is still turning normal RPMS... Thus the ~normal oil temps. Friction~- RPM, and friction is heat.

A high power condition adds to it, but IIRC Jake found that on his spintron setup (no pistons/rods IIRC) he was still getting hot oil just from spinning the crank/cam/rockers/valves etc and pumping oil at typical RPMs.

Took significant power too: That power ended up as hot oil, mostly.

Another example that a big oil pump is probably not really your best friend.