intake manifold coolant port question.

[1970mule]

ok well, i know now that edelbrock no longer puts the rear coolant ports on their performer intakes. so my question is how does this affect the engine, it seems not to make sense that it does not have a use now. I mean how does the coolant flow thru from back to front? ?:?

 

[Viperwolf1]

Coolant flows through the block and up in the back, into and through the heads to the front.

 

[1970mule]

so why doesn't the new design with 2 less ports in the back not cause any problems?

 

[Viperwolf1]

so why doesn't the new design with 2 less ports in the back not cause any problems?

Because the coolant needs to run all the way through the length of the head anyway. Remember the coolant comes straight up from behind the last cylinders and into the heads and out the front of the heads.

 

[1970mule]

oooooooooook, gatcha now i see. sorry i was confused. i put alot of work into the engine and did not want it going fubar by something silly . thanks viperwolf1

 

[blubuckaroo]

The reason for the port at the back of the heads is because both left and right heads are the same casting and can be used on either side. They only need a port on the front. Some aftermarket intakes have both. I have to question their engineering staff's reasoning. I've actually had one Edelbrock Performer manifolds with and one without.

 

[1970mule]

thanks also blubuckaroo.

 

[DirtDonk]

What are you building there 1970mule? Reason I ask is that, last I heard, the ultra high perf crowd, especially on 351's, still use a special crossover circuit between the heads in the back ports to keep steam pockets out of the combustion area.
Not needed for most of us, but if you're building a 351 race motor, I just thought I'd mention it.

Paul

 

[1970mule]

OH no Dirtdonk, i like to squeeze every drop out of my 302, i just wanted to know what the major difference and or benefits if any to the old and new style of intakes. but i am leaning more to building an over all rig, with more pre-running in mind. but i still like to do some crawling and mudding. but out here we have a surplus of sand so thast where i will start

 

[Broncobowsher]

There was a time when Ford used the water from the rear crossover. And it isn't steam pockets. Back in the early 80's Ford was using the water to cool the EGR gasses. to keep the flow even through both banks of the engine, they put in a crossover. Then tapped water from the crossover to cool the EGR. Why take water from the crossover? couple of reasons. One was the front of the intake was already crowded with temp sensors and thermo ported valves. Second is the water is cooler there. The water had only traveled from the water pump through the cylinders to the back of the block. It is after it rises into the heads and flows forward does it pick up the majority of its heat. So it had cooler water to cool the EGR gasses. Since many of the intake manufacturers were doing there best to remain emissions compliant, they added the crossover in order to stay in the market. Even on the non-emissions castings. Same basic casting.

There should not be any flow between the ports at the back of the heads. For those of you stuck on the steam pocket theory, where do you think the steam is going? Do you really think it is leaving one head and traveling into the other?

 

[DirtDonk]

There should not be any flow between the ports at the back of the heads. For those of you stuck on the steam pocket theory, where do you think the steam is going? Do you really think it is leaving one head and traveling into the other?

Why would steam moving from one head to another be desirable anyway? I'm guessing there was some other dynamic at work rather than just pushing steam to another hot spot though.
I don't have any personal experiences with it anyway, so I'm not stuck on anything other than what 35 years of hop-up artists held as an absolute. Seems that the crossover changed the flow pattern in the rear and reduced the instances of steam pockets forming in remote corners and such. Or something to that effect.
Don't know from theory, but if not steam pockets, then apologies for my memory lapse. But the modifications were indeed performed for some reason. Often by seasoned race engine builders. That, and the fact that many many people talked about it, wrote about it in magazines, performed the mod and said it worked, still remains. Whether or not they were smoking dope at the time remains to be admitted.
Seems to me we've even spoken of it here on the forums a time or two. Hopefully some members here who have actually done it can shed some light on the subject.

What's your actual take on it?

Paul

 

[broncnaz]

While I havent done it and some of the actual performance mods are quite a bit different than just a rear cross over as most run a line from the cross over to the water pump. Here's my understanding of the reasoning. the mod/rear crossover helps water circulation preventing hot spots and probably steam pockets as well so in a Hipo application it has great benifits. In a standard application the benifit may not be as noticeable although some people have gotten lower coolant temps with this mod. Overall If your not having unfixable cooling issues then its probably a mute point. But if you've tried about everything else it may be a option. I kinda wanted a rear crossover as most of the old aluminum manifolds without the corssover have been badly corroded at the rear water ports some even develop leaks that are hard to seal. so I think the cross over would slow down that issue.

 

[Viperwolf1]

If the cooling system pressurizes as it should there won't be any steam inside the engine.

 

[broncnaz]

Not always true. Air pockets tend to get trapped in high spots pressurization has nothing to do with removing them. In reality its steam that creates the pressure most is released through the cap but if its trapped in a high spot it wont move.

 

[Viperwolf1]

Pressurized pockets of air and steam are two different things.

 

[DirtDonk]

At first perhaps. The way I understand it though, whether it's a trapped pocket of air or a corner where coolant flow is hindered for any reason compared to the surrounding areas, the heat buildup in that spot is great enough to create steam due to the high localized temperature.
Like I said though, I'm not a cooling system engineer, but that scenario sounds very plausible to me. Even still as I'm writing about it.
But then, I've fooled myself before...

Paul

 

[Quick & Dirty]

I have to question their engineering staff's reasoning. I've actually had one Edelbrock Performer manifolds with and one without.

What I've seen is the Performer EGR has the rear crossover, the non EGR doesn't. Makes sense if the factory used the crossover for cooling the EGR.

Performer 289, vs Performer 302 (EGR)

Seems to me the Performer 289 is more power oriented, while the Perf 302 is emissions legal.

351W (#2181)

351W EGR

 

[blubuckaroo]

No, it has nothing to do with the EGR. I've had a 2121 with the crossover port and one without.

 

[BoltBuster]

Why is this such a good tip then?

http://classicbroncos.com/tech/351-cooling-tips

 

[blubuckaroo]

I don't know if it would be needed. The author stated that the front ports were partially blocked by casting mess. Maybe fixing that would have been sufficient. Looks like a lot of leak sources. I've seen a lot of good running 351Ws without all that.