Head cooling on cylinder #5 - solutions?

[Xnke]

Or better yet, has anyone considered the Z2(x) series water pumps? I have heard on several forums that they have a larger diameter *cast* impeller, as opposed to the smaller folded sheet steel impeller of the L-series pumps. Looking at http://www.allwaterpumps.com, I found several different types of L and Z series water pumps with the same part number, and some had cast impellers, others had folded sheetmetal. The cast impellers looked like they filled the housing more. Anyone got experience with these?

 

Maybe with a larger impeller, the flow could be increased enough to make a difference.

[Tony D]

The LD28 has a larger impeller. This is documented in another thread.

 

The folded metal pumps are junk, and are an aftermarket unit, the stock Nissan pumps are all cast impellers.

 

I have often thought of having an impeller cut on a five axis using some developmental software we have at work...it's just getting time in the milling machine without anybody looking...

 

Personally, I paint all the cast impellers with Glyptal before installation. When one finally craps out, I'll dissect it to see if it helps prevent corrosion and/or cavitation damage to the impeller.

[ktm]

Tony,

 

I've been running my car with the setup we discussed (#5 into turbo, #6 into lower T-stat housing) and the car is running much cooler, even when running it HARD, the engine temps never get above 88 degrees C - hard as in repeated, back to back 2-3-4 redline runs. The needle never even covers up the F on the gauge and Wolf shows it running around 88.

 

When cruising, the temps drop to below 80 degrees.

[X64v]

Good to hear it seems to be working. My head still needs to be dropped by the machine shop, so it'll still be a while before I get it on the car.

 

How about ping? Any change in tolerance?

[ktm]

Sean,

 

I am running a 50/50 mix of 91 and 100 octane as well as meth injection right now. The 50/50 mix is for precaution as I tune for methanol, so I can't tell you about detonation tolerance.

 

I am amazed at how much cooler it is running though, and I have not blocked off my front radiator support or sealed any lower gaps.

[Slow_Old_Car]

pics!

[Six_Shooter]

pics!

 

x2.

 

I'm interested in keeping my head gasket in the shape it's in now, once I put the turbo on, and know that cooling is paramount, in keeping everything together and working.

 

I'm not going to be using a water cooled turbo, I also don't know where the water cooled turbos return thier water to.

 

So I would think that returning both fittings above 5 and 6, to the bottom of the T-stat housing, would do the job.

 

I'll have my intake off soon, for the EFI swap, so I'll drill and tap at that point.

 

The best solution I think would be to place the T-stat, or at least the coolant return at the back of the head. The T-stat could still be located neare the front of the engine, just fed from a tube or manifold that is fed from a fitting at the rear of the head.

 

Hmmm, I really wasn't planning on pulling my head, since I just want to play with the L28 in my car for the next year or two before I swap in a larger V6.....

 

Just as reference for other cooling modifications on other engines:

 

The small block Doge guys like to drill and tap the water pump outlets (feed to the block) and run a 3/8" to 1/2" hose to the two block drain ports, about midway in the block. It was found that this helped push the stagnant water/coolant from the bottom of the block, where it's really not needed out through the heads, providing a significant drop in engine temp, some say as much as 20 degrees. A Froiend of mine who ran Dodge engines in his dirt cars, found this to be accurate, and actually had to resit to running a T-stat instead of just a restrictor, to get the engine warm enough.

 

Other modifications are very similar to what is being proposed here, is to drill and tap the intake at the rear, where the heads have ports that would line up with the coolant passage at the front of the engine, that leads back to the T-stat. The modification in this case, uses tubes or hoses about 3/8" in diameter and plumb them back into the intake at the front in that same passage that leads to the T-stat. This is done to equalize the temp accross all the cylinders, since it's been found that in a lot of cases the coolant goes through a cycling that is similar to what was posted back on page 2 (IIRC) of this thread where the the coolant doesn't really exit the engine, but cycles around the same cylinders.

[ktm]

As soon as I can get my hands on a camera, I'll take detailed pictures. I've asked to borrow my neighbor's camera (wife has ours) and will post pictures as soon as I get it.

[ktm]

Pics, I got pics. Nothing like a picture to show you how dirty your engine gets in So Cal's air.

 

The first picture shows the 1/4-in. NPT to -6 fittings above the #5 and #6 exhaust port.

 

The second picture is a general overview of the engine. You can see that the hoes from #6 goes up, over, then back under the intake manifold and connects to the lower t-stat housing. The reason for this convoluted shape is clearance. You can not run a -6 line under the intake runner without affecting the orientation of the fuel injector. The #5 hose feeds the turbo. The outlet from the turbo then goes to the stock bypass line shown in picture 4 (its the braided hose that goes around the distributor).

 

Someone is bound to ask about the silver foil line and heat shield. The foil is actually reflective tape over a 1/2-in. neoprene hose insulator that covers a Goodridge fire sleeve over a 1/2 stainless steel hardline. Why the triple redundancy? I am having issues with my methanol boiling and thereby having no methanol pressure. I have tracked it down to the pump as the culprit, hence the heat shield (I will clean it up a bit if it all works out).

 

The third picture shows the stock bypass hardline. I cut the ends off and silver braised -6 AN fittings on the end.

 

I hope this helps.

[Six_Shooter]

Cool. looks good.

 

The turbo coolant return then goes where? To the port at the rear of the block (head?) on the passenger side?

[ktm]

The turbo coolant return then goes where? To the port at the rear of the block (head?) on the passenger side?

 

The turbo coolant return goes to the water pump inlet via the stock bypass hardline. If you look at picture 4, notice the braided hose to the left of the distributor? That is the turbo return feed. It attaches to the bypass hardline when then conveys the coolant to the water pump inlet shown in picture 3.

 

The rear of the head is plugged.

[Six_Shooter]

Ahh, ok, cool, thanks.

[TimZ]

Interesting solution - just a couple of comments on the hose routing, though...

 

Hopefully it's just an illusion from the pic, but it sure looks like the hose from #5 is really close to the exhaust manifold. Standard SS braided hoses are only good to ~350degF. The coolant flow through the inside should help some, but the SS braid will transmit heat from the exhaust manifold directly into the outer sheath. You should at least put some firesleeve over that section.

 

Also, probably a non-issue, but it looks like you have a pretty high loop in the hose from #6, which might make it difficult to get trapped air out of it. The fact that it's routed back to the lowest pressure point in the system should mitigate this. Just remember that the water has several choices as to the return path it takes. If it ends up taking a bigger pressure differential to push the trapped air out of the hose than what is present, the water will simply find a different path and the air will stay in the hose.

[ktm]

Tim, thank you for the comments. This is not the final solution and is still a work in progress. The loop you are referring to had me concerned for the same reaons you mentioned. I am looking at ways to reduce the height of the loop. As you rightly said, it is all about pressure differentials.

 

The fire sleeve for #5 is a good suggestion.

[X64v]

Here are some pictures of my setup (finally got it all installed this week). I haven't had a chance to evaluate the effectiveness of this yet (i.e. hard repeated runs), but so far it certainly hasn't hurt anything.

 

 

 

The hose running from the T connects to the metal Y pipe where the original carb heater line used to join in with the cabin heater return. I'll post a picture of that when I post a testing update.

[Careless]

Hi X64v,

 

that looks awesome. what kind of hose is that bright blue stuff?

 

May I ask why you did not run a straight 180' fitting rather than a 90' angle fitting to the side? Or was it a direct heat issue? I think making a small cover plate to separate the two and having a the 90 turned the other way and going into another 90 would make it seem invisible.

 

but it does have that coolness factor.

 

Also, i've never quite seen this on an L head before, but are those punched out exhaust ports and liners fitted to the old square shaped exhaust ports?

[Xnke]

Nope, that's a P79. It's just clean.

[X64v]

what kind of hose is that bright blue stuff?

 

It's Aeroquip Push-Lok hose. Earl's also has it under the name Super Stock hose. The only difference between the Earl's stuff and the Aeroquip is the outer texture; Earl's is smooth and a tad soft, the Aeroquip stuff is knurled and hard (which I prefer). I used the Earl's Super Stock hose ends with the Aeroquip hose.

 

Many people talk down about it, but I really like the push-on hose. It's very flexible, super quick and easy to work with, and the hose ends are less expensive.

 

 

May I ask why you did not run a straight 180' fitting rather than a 90' angle fitting to the side? Or was it a direct heat issue? I think making a small cover plate to separate the two and having a the 90 turned the other way and going into another 90 would make it seem invisible.

 

I did it that way 'cause it's the first plumbing set up that popped into my head, and seems to work just fine. A 90 degree fitting and straight hose end is cheaper than a straight fitting and 90 or 180 degree hose end.

 

And yes, it does have it's cool factor, which is why I had no problem routing that hose above the intake runners and having all the AN fittings exposed.

 

 

Also, i've never quite seen this on an L head before, but are those punched out exhaust ports and liners fitted to the old square shaped exhaust ports?

 

Nope, just a plain old P-79. The machine shop did have to take a tad over .100" off the manifold mating surface to remove some imperfections due to corrosion, so perhaps that's why it looks different than normal.

[TimZ]

It's Aeroquip Push-Lok hose. Earl's also has it under the name Super Stock hose. The only difference between the Earl's stuff and the Aeroquip is the outer texture; Earl's is smooth and a tad soft, the Aeroquip stuff is knurled and hard (which I prefer). I used the Earl's Super Stock hose ends with the Aeroquip hose.

 

Many people talk down about it, but I really like the push-on hose. It's very flexible, super quick and easy to work with, and the hose ends are less expensive.

 

Not me - as you said, the push on hoses are much easier to work with and have more than adequate pressure capacity. Plus, it's lighter and doesn't eventually destroy everything it comes in contact with. I'm slowly in the process of converting all of my SS braided hoses to either push-lok or the Nomex-braided hoses(Start-lite, Pro-lite, etc) etc.

[Slow_Old_Car]

.10 here...

 

is there a reason ya'll are tapping these rather than just drilling and then tigging on a bung to the two hole areas?

 

i'm just curious if there is any answer to this that isn't "because i don't have a tig"

 

cause if thats the only answer, i think when i do this i'll try tigging on bungs.