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Discussion Starter #1 (Edited)
Anyone catch the latest episode of Engine Masters on MTOD about hot intake vs. cold intake's effect on power?

I bring this up because of the long debated topic of blocking the heat crossover in BBF's, and it's effect on power.

Long story short.....heating the intake manifold made ZERO difference in power, but icing the intake increased power, but not because the intake itself was cooler. The big power gain with icing the intake is because it cools the fuel in the carb!

I predict a spike in Cool-Can sales this summer. :laugh:





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I've mentioned this before and will again.

We've on several occasions blocked the cross over in an iron headed 460 hp combo with brass shim stock knowing it would blow through after a couple of pulls. This is with an aluminum intake and jomar spacers to isolate the carb from intake manifold heating.

When the manifold got hot it hurt torque by over 20 pound feet at the peak. Hp to a lesser degree due to latent heat of vaporization at rpm but never the less...

Now increase air intake temps under a hot hood.

Do with that information what you will.

C 66

If the heads do not have a cross over RPM vs. Air Gap would not see a bunch of difference. as evidenced by the BBC test referenced.

Correction: the discontinued heads DO HAVE a heat crossover. I looked at the wrong pic.


SJ
used 2b RHP
 

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What kind of engine platform?
Intake style?

Drag racers have been icing dry EFI intakes for decades for faster ET's.



SJ
 

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Discussion Starter #5 (Edited)
IIRC, there wasn't a lot of difference in dyno testing the Edelbrock RPM vs RPM air gap on the dyno. I don't think it was a 460 test though, and it was years ago. Here it is:


https://www.hotrod.com/articles/hrdp-1111-differences-in-power-or-not-edelbrocks-rpm-vs-air-gap/



The regular RPM appears to have a heat crossover in the pic.


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Interesting. And the heads referenced in that article do appear to have heat crossover passages in them.




Given the difference made with just fuel temp, it seems paying attention to under-hood temps via header coating/wrap, fuel line insulation, carb insulation, etc. and running a return loop fuel system vs. a deadhead could yield substantial power gains.




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Back in 1963 we raced a 426 Mopar B-Wedge and used a big coffee can with a cooper coil inside that we filled with dry ice before each run. We were running one day at Detroit Dragway when Don Nicholson ( was doing a match race)came by and spotted the setup and told us that he needed something like the setup we had. I think that was before the Cool Can came to be, the idea is sound to cool the gas before it enters the carbs.
John
 

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Discussion Starter #7
Back in 1963 we raced a 426 Mopar B-Wedge and used a big coffee can with a cooper coil inside that we filled with dry ice before each run. We were running one day at Detroit Dragway when Don Nicholson ( was doing a match race)came by and spotted the setup and told us that he needed something like the setup we had. I think that was before the Cool Can came to be, the idea is sound to cool the gas before it enters the carbs.
John
That was a little before my time. I spent most weekends "cruising" Telegraph Rd. in Detroit in the 80's, and the two things that were a dead give away under a guy's hood back then were a vacuum can, and a cool-can.

Seems the cool-cans are mostly out of production, but there are quite a few used ones on ebay for ~$100.00.

oh, and back to the dyno test....they also heated up the carb while icing the intake, and it took away all the gains they saw from just icing the intake. So, if you're not doing something to control the fuel temp, it sure seems like any effort at cooling the intake (divorced runners, blocked crossover, etc.) is a total waste of time.




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The NHRA has banned the use of cool cans as far as I know. No artificially cooling of fuel after it's put in the car whether it's cold water, ice, dry ice, Freon. Once your in the staging lanes better not be caught with it.
 

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I use a holley 130 mechanical fuel pump on my LTD.
Even with coated headers, a heat isolater for the pump and insulated fuel lines the AF ratios at idle, transition and WOT lean as the engine warms. Watching this happen with the FAST wideband was / is fascinating.

In short order I simply jetted for proper AF ratios when the old broad was up to operating temp and the outside temps were in the 70's as it typical here in the PNW. Sorting out idle, light accel and WOT took some time but the effort was worth it.

Keeping the air charge as cool as possible via a sealed ram air system and cool intake (typically 160 / 180 f give or take when heat soaked) are things I can control to an extent.

When it is really hot out say in the 80's to 90's, fuel temps go up and density goes down I can again watch the AF's continue to go leaner. If I am at the track tuning for that last 10th I can simply re-jet and recover some of the loss.

At first it seemed counter intuitive that WOT would go leaner as the EOT, air inlet temp and fuel temps rose but my wide band tells the story. The next engine I build will get TBI. Hell maybe this one will. :D

The latent heat of vaporization with heated fuel is not as effective at cooling the intake charge so I can certainly see how a cool can would work but there are two separate issues here.

Keeping air temp and fuel temp as cool as possible is simple common sense.


SJ
 

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Discussion Starter #11
The NHRA has banned the use of cool cans as far as I know. No artificially cooling of fuel after it's put in the car whether it's cold water, ice, dry ice, Freon. Once your in the staging lanes better not be caught with it.
I guess that explains why they're out of production. No such rules in 1/2 mile or standing mile events that I run though.

I wonder how much good an external fuel cooler would be? Something like a trans cooler in front of the radiator, but run fuel through it instead?





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The NHRA has banned the use of cool cans as far as I know. No artificially cooling of fuel after it's put in the car whether it's cold water, ice, dry ice, Freon. Once your in the staging lanes better not be caught with it.
Had to have changed after the 1963 Winter Nationals with the setup I mentioned, we also ran at the 63 Nationals at Indy
 

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Yeap Watched it I`ve seen all the episodes and power nation engine power. Lots of good info. Yeah I was doing that 25 years ago And that's why I run methanol on my big hp race engines A couple quick revs with methanol - your intake is ice cold - plus the fuel is always cold if you have it plumbed right
 
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