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-   -   Use your A/C to cool your engine! (http://forums.pelicanparts.com/porsche-911-technical-forum/273344-use-your-c-cool-your-engine.html)

Duckworth 03-26-2006 08:10 AM

If it were 1975 right now, and Porsche had poured money into a prototype 3.0 litre motor - using an experimental water cooled cyl head - can anyone imagine how well, or not so well it might have worked ?

If millions $ had gone into the project insuring that the motor had a teutonic, professional look about it and plumbing done in a superb manner - it's a strange hypothetical of what 'might have been.'

Fan housing would be out altogether and alternator over to the side - as 911mot suggested. Lots of room at the center for the pump (belt driven)....

Let's get busy ! ..:eek:


Phil

Duckworth 03-26-2006 03:22 PM

.....hope you guys will stick around a bit longer - thread seemed to die with my last post.



Phil
_________

'80 928
'82 Targa - sold

kach22i 03-26-2006 03:51 PM

Quote:

Originally posted by Duckworth
If it were 1975 right now, and Porsche had poured money into a prototype 3.0 litre motor - using an experimental water cooled cyl head - can anyone imagine how well, or not so well it might have worked ?
You must be talking about the 959.:)

Off by six years?

http://en.wikipedia.org/wiki/Porsche_959

Quote:

Development of the 959 (originally called the Gruppe B) started in 1981....................

Porsche began with an engine they already had, and moved on with development from there. The powerplant, a twin turbocharged boxer six engine, with an air cooled block and water cooled heads displaced 2.85 total litres, about half a litre less than a contemporary 911 engine.

patkeefe 03-26-2006 03:57 PM

Can you still buy an air cooled Porsche at the dealer?

RoninLB 03-26-2006 04:51 PM

Quote:

Originally posted by Duckworth


.....hope you guys will stick around a bit longer - thread seemed to die with my last post.

I'm going to have some hard info around by Tuesday concerning the 65mph, 5th gear, 4th gear posts above.

I can very accurately measure CHT on all 6cyl under all conditions using the plug gasket sender. The thing is the test will be low key to keep from getting arrested.

My current position is that those with high oil temps need bigger oil cooling. Achieving max hp combustion without detonation is partially related to low oil cooling.. imo so far.

bigchillcar 03-26-2006 04:58 PM

ron..keep in my mind that for my test..there was no (still isn't) auxillary oil cooler..
ryan

RoninLB 03-26-2006 05:41 PM

Quote:

Originally posted by bigchillcar


ron..there was no (still isn't) auxillary oil cooler..


oh.. I didn't know that.

A single engine oil cooler + the hoop fender cooler is maybe good for a 150hp engine, can't really say. A simple thought is the more hp the more oil cooling necessary. More added power than good stock means more wasted heat must be channeled away some how/one way or another if heat control was borderline before. Your combustion chamber is the center of the power universe. Heat control of this chamber is absolutely necessary when building more hp. Adding more fuel to control detonation at high hp levels without proper heat control is more of preventing the engine blowing up than proper operation. The conventional knowledge is that added fuel itself cools combustion just as throwing water on your face to cool down does. It's wrong imo. The added fuel is slowing down the speed of combustion and is a sort of ignition timing retard. Combustion speed varies not just with the piston pressure but with the A/F mix. That method may be safe but it doesn't allow the theoritical max hp.

what's that said !

bigchillcar 03-26-2006 07:14 PM

ron..i'll still be interested to see what your result is with an auxillary cooler. i suspect the difference will be less dramatic than mine. in other words, i think your temps will increase cruising in 4th for an extended period, say 30-60 minutes, but not as much as in my car. we'll have to wait and see.
ryan

RoninLB 03-26-2006 08:54 PM

Originally posted by bigchillcar

auxillary cooler.
-------- I have the Lemke front right and I may have to do a front left cooler also. I missed a ride to the 4 Corners last May to find out. If I don't need a front left cooler these carbs are going to impress me again. Right now all I can figure it's a 50/50.

i think your temps will increase cruising in 4th for an extended period, say 30-60 minutes,
-------- that means my oil will be gathering increased heat from somewhere. Somewhere has to be my CHT. Greater heat from CHT has to come from excess heat of combustion. More combustion heat means I'm creating more power at the engine. I guess so until someone tells me I'm wrong.

More power = more heat.. so then If I downshift and create more CHT heat then it should eventually be reflected in oil temp heat. The oil temp heat lags maybe a minute or two behind CHT before you can actually get a clear idea that's it's starting to move. That was figured in summer Rockys, summer high deserts, etc, at around 3.5-4k in 5th.
Around here I'll figure oil temps within 20mi in each gear.

So then.. Am I making more power from the engine when downshifting?
I don't think so because of gearing? Without a log then all I can say now is that it don't happen. I should be able to spit out the hard #'s but I pay little attention to slight specific oil temps. I watch CHTs like a hawk w/oil secondary. It's one of those "it's good enough" things.

I kinda hit a brick wall now 'cause I'm sure the gearing affect on combustion power output is not linear. But it's only gonna be a series of 65mph straight pedal runs thru the wetlands. It's a 12mi straight with 7mi of HP freedom w/plenty of U turns available. It's where I jerk around with my testing. That's where i got the 5th gear, 4k CHT #'s from. Flat, straight, fixed rpm, consistant humidity, no cars, no HP.. perfect for baseline tuning imo. I'll know oil temps within 20mi in each gear.

Jim Sims also threw his thoughts in this mix which I think are unintended consequences concerning other issues. I think?

but not as much as in my car. we'll have to wait and see.
-------- a 2.7 is crippled unless it has a good front cooler. A start is a fender cooler. It's a glorified air cooled VW when naked.



I could be nuts on all of above and before?


ryan/ Ron [/B]

Duckworth 03-26-2006 08:57 PM

Quote:

Porsche began with an engine they already had, and moved on with development from there. The powerplant, a twin turbocharged boxer six engine, with an air cooled block and water cooled heads displaced 2.85 total litres, about half a litre less than a contemporary 911 engine.
Good point Kach22i. But a 3.0 to 3.4 normally aspirated motor using a belt driven waterpump - rather than the shroud and fan assembly - would maintain simplicity and alleviate heat concerns. More than a Subaru motor - something that could function and appear as clean (or almost ) as an MFI 911 motor.

In other words a 'flat' motor that stays extremely flat - one without every supertrick item taking up every cubic foot of space, as in the 959...But water into those cyl heads and back again to the pump. Goal: 220 - 240 horsepower with no detonation and summer trips to Tuscon or Death Valley if desired.


Phil
____________

'80 928
'82 Targa - sold

bigchillcar 03-26-2006 09:23 PM

well, as far as being 'crippled', ron, i'd bet you're right under hot track conditions..wouldn't doubt it for a second, in fact. high temps and humidity in arkansas sometimes make my car TEMPERATURE limited during summer highway cruising. in other words, i can't maintain 90 mph for too long without temps beginning to creep into the 230, 240 range, etc. if i keep it at 80 and under, i can stay close enough to the magic number 220. i'd love to add a cooler..until then, i can drive balls out until it gets close to 80+ degrees.. :(
ryan

RoninLB 03-26-2006 09:37 PM

you need cams.

bigchillcar 03-26-2006 10:12 PM

Quote:

you need cams.
i actually think i prefer the basic cams over the 's' cams available in '74, at least for street use i think they're fine..no doubt i'd have more breath in the upper ranges with the 's' cams. now, whenit comes time to break this puppy down..who knows what the devil i'll do.. ;) in the meantime, i need that front cooler more than anything..and you'd have to agree, ron! SmileWavy
ryan

Duckworth 03-27-2006 06:07 PM

There are thousands of you out there who have gone to some pretty great lengths to control temperatures.

...many of you are working engineers. My Dad was a successful engineer - I don't have as much training as you engineers. But my bet is there is a ton of engineering left in a 911.

The 928 of mine is a nice car but w/ more weight can never give the 'feel' of a 911. I would like another vintage 911, but with a motor that I can live with in any climate. In a previous thread Grady mentioned about his attempt years ago with a liquid cooled head....few seemed interested - regardless, that to me was a great idea.

My interest has always been long distance cruising - as opposed to track events. Cross country to me is the ultimate. So, water flowing thru the heads of a protoytype 911 engine would knock my socks off. If I had Seinfeld's banking - I would be modifying aircooled motors for liquid cooling. Rather than just purchasing and collecting millions of dollars worth of rare Porsches - and polishing them for 'concours'. But it's his money to do as he pleases.

Phil
________

'80 928
'82 Targa - sold

RoninLB 03-28-2006 03:30 AM

Quote:

Originally posted by Jim Sims
[BI've observed this too in my 911 and attributed it to the increased pumping and friction losses due to the engine turning at a higher rpm; part of the losses will show up as hotter oil and higher CHT.[/B]
Quote:

Originally posted by RoninLB I'm going to have some hard info around by Tuesday concerning the 65mph, 5th gear, 4th gear posts above.

My oil temps rose.

45F ambient, 170F oil in 5th, 170F + 1/2 thickness of the needle in 4th.

I couldn't notice any increase in CHT although the group of cyls must have risen a bit.

bigchillcar 03-28-2006 12:21 PM

Quote:

My oil temps rose.
yep..another data point that supports my experiment last summer. either with or without an aux oil cooler, all else being equal, oil temps rise switching from 5th to 4th gear for crusing in hot and even 'not so hot' weather..
ryan

RoninLB 03-28-2006 12:23 PM

it seems my rise would be more radical under more demanding ambient temps.

bigchillcar 03-28-2006 12:30 PM

Quote:

it seems my rise would be more radical under more demanding ambient temps.
i'd intuitively agree..and even moreso without an aux oil cooler.. ;)
ryan

Nitrometano 03-28-2006 01:52 PM

My neighborg 2004 supercharged Mustang Cobra with 659 hp use the a/c to cool the fuel into an homemade cool can. He is planing now to cool the water that recirculates thru the water-intercooler inside the intake manifold. I think that he is "thinking outside the box".


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