All Things Chev

[poindexter]

this image shows simplistic airflow, underbody is considered low pressure

Aerodynamics_DragLiftDownforceOverBodyFlow.png

[PeeBee]

this image shows simplistic airflow, underbody is considered low pressure

Aerodynamics_DragLiftDownforceOverBodyFlow.png

Wish I had this image before I blabbed on for 1000 words last night! So negative below engine and on 2/3 of bonnet.

[rainsey]

Running lean will make things cooler in a diesel.

Lower twmp thermostats wont reduce your under bonnet temps. 2 extra cylinders pumping out heat will bring them up. I would be more inclined to be looking at reducing the radiant heat from the exhaust manifolds. This can be done in the form of coatings, wraps or heat shields.

Thanks for the feedback. I understand that the thermostats will not affect the under bonnet temps, but what they will do is cut in earlier and get the water in the block circulating earlier hopefully reducing my water temp from what it is currently reaching.

My Turbo has a cover and the exhaust is rapped all the way down so yep, this is accounted for.




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[PeeBee]

Oh. My other thought was in regards to the excessive heat in that hot air does rise. If this was the case it would exacerbate the whole under bonnet pressure issue .... i think..


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Heat in the form or radiant heat is not related to pressure and air flow, so as the low pressure zone pushes the air to the road, the radiant heat in the form of conducted heat, causes the metal components to rise in temp, heating the air locally - can only be local because air is a poor conductor, hence if you allow a vent path, vertically, the airflow will strip the latent heat from the surrounding area by erosion.

[PeeBee]

Guys, when sorting out the fuel flow issue on the aux tank tonight I saw first hand just much of a fuel flow is leaving the tank to feed the engine. My aux fuel tank was custom manufactured and its apparent that level dampening is not marvelous, because when the vehicle is idling, the fuel gauge needle is static, but increase revs to 2000-2500 and the fuel needle dances over in time to the demand. Its amazing how dramatic the flow pattern is. certainly having the hose , which is 8mm dia, choked off by maybe 50% had a dramatic impact. Something to watch for with older vehicles perhaps.

[Kimbo63]

G'day Rainsey, sorry no ones got back to you yet mate. Seems the only 6.5ers posting at the moment are Turbo&Intercooless NA's :-) Engine bay air pressures of big donks squeezed into smallish trucks has been one of my concerns for a while now. Finally about to install my NA reverse scoops wacky concept to increase theoretical flow through. I must admit the physics of top Chev/Trol mounted intercoolers with forward facing scoops has always confused me for fighting air pressure performance. Front mount IC is probably the go but again more hinderence to your already stressed radiator system. @Kimbo mate, how does your beast run so perfectly as driven :-)



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Hey mate just seen this have been busy working and no time to get on the net
I think my truck runs cool due to good air flow my front bar is very open and offers no restriction to air flow also I got rid of the flex radiator hoses that BD fit and used silicone hoses and Aly pipes

[jay see]

I haven't read much on this thread, so if it's been mentioned already apologzie.

Have played around with low/high pressures on the last 4by I had.
Vents in the lower part or the bonnet (like what a Subaru sti have) are something to consider. So is chocking up the rear of the bonnet (closert to the windscreen)

[MB]

I had choked up my old DX4.2TD bonnet years ago and to the best of my memory what NNB and Poindexter have kindly posted above makes sense now. It did seem to help at low speeds but that high pressure zone pictured above at the windscreen base must have been the issue at high speeds. Reckon I'll still give the cheapo Saas reverse scoops a go somewhere in the middle of the bonnet low pressure zone. My NA truck finally goes up to Mansfield later this week for a free flowing new Millweld bar with built in oil coolers far left and far right and I'll piss off the last flexy top radiator hose too thanks Kimbo :-)
Rainsey mate, in regards thermostats, I researched heavily the yank sites from posters in the snow and desert regions, consensus seemed to be the ACDelco 88DCelsius for best all year round. About $40Aud each from Autobarn-USA online.

[rainsey]

Rainsey mate, in regards thermostats, I researched heavily the yank sites from posters in the snow and desert regions, consensus seemed to be the ACDelco 88DCelsius for best all year round. About $40Aud each from Autobarn-USA online.

MB,

Thanks for the info. Re the thermostats, yes it appears the 88 degree units are what Greg from BD thinks is in my engine. Now not really having any knowledge of what I am saying.... Greg also stated that they do not fully open until around the 95 degree mark. Sooooo on that thinking he is sending me a lower temp high flows.

Watch this space. When I get them I'll see if they make any improvement.

Kindest Regards
Rainsey


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[MB]

Made a quick video for you mate that may be helpful.

The Yanky 88's currently installed outperform the originally installed Aussie 82's by miles. I've done each cooling system mod slowly over stages and the best stability mod noticed to date was these thermos even throughout 35+ Vic heat this summer at times up our test hill.


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