Head cooling on cylinder #5 - solutions?

[Daeron]

I don't think people were noticing without a link or the pics popping up right in their face.

 

 

Support for that theory!!!!

 

 

My reaction to seeing these four pics was "Holy freakin CRAP his engine bay is gonna be nice!!"

But this neck on the left needs some more cleaning to be up to par, man!

[Tony D]

I did -6 (3/8" NPT taps) on mine with no problem. Here is a link to my project post for this mod. I don't think people were noticing without a link or the pics popping up right in their face.

 

http://forums.hybridz.org/showpost.php?p=1025069&postcount=13

 

WOAH!

That looper aroudn the back of the head to the water pump inlet is not doing you any favors, as a matter of fact you'r putting the hottest water in the head back into the inlet of the pump---terrible! That needs to go to a COOLER before being recirculated to the inlet of the pump!

[ktm]

Tony, remember your discussing about expedience earlier in this thread?

[jeffp]

Ok so with all of this discussion, I think I am going to jump off this cliff and have the cylinderhead done from #2-#6. I don't think #1 is really an issue as it is right at that large hole for the thermostat housing. I have completed #5 & 6, and was intending on doing # 3 but between 3 & 4 is difficult to do. I have already invested about 300 in what I have done, but the union T I used (swedgelock) is to big to get between 3 & 4 so a redesign is in order.

I will get the 1/4 NPT fittings, do the intake clearancing for 3-4 use the A/N fittings and run the tubes to a common tube 1/2" but instead of using fittings have each tibe TIG welded to the common return pipe. I use a local welder here Master Craft Welding to do the work. This guys TIG welding is the best I have ever seen, very percise and very clean. I have him do the work I want to look good and be strong. I have already bought all of the -6 45 1/4" NPT fittings. Getting around the head stud between 3-4 is going to be the tough one, but I think it is doable. And just to make sure where it needs to go, I have a good door stopper P90 head I will section to make sure of the fitting locations.

Why is it that every time I get involved in this stuff it starts costing me lots of money LOL, but its only money right? Anyway this is just part of the crap I am working on right now, and since I just dropped close to 4 grand on components for a race head what the hell!

[WizardBlack]

WOAH!

That looper aroudn the back of the head to the water pump inlet is not doing you any favors, as a matter of fact you'r putting the hottest water in the head back into the inlet of the pump---terrible! That needs to go to a COOLER before being recirculated to the inlet of the pump!

 

Bo's goes through a turbo (to get heated even more) before going to that point. Expediency is true, yes. It works, so I am happy. I think making the flow even was a higher priority than overall load on the cooling system. It's not a perfect solution, I know. I also reasoned that this would help boost the flow through those two cylinders versus routing both to the t-stat housing; helping overcome the natural restrictions in the head jacket there.

[WizardBlack]

Support for that theory!!!!

 

 

My reaction to seeing these four pics was "Holy freakin CRAP his engine bay is gonna be nice!!"

But this neck on the left needs some more cleaning to be up to par, man!

LOL, thanks. Overall pics are on my build thread (in my sig). I need to update it, but my "to install" stack of parts is getting larger than my accomplished list.

 

The neck is corroded a bit, so definitely difficult to get really clean. The inside is deburred, smoothed, etc. just like the front cover's coolant circuit, however. Eventually (if I still stick with L-motors) it will have a nice billet plate with AN fitting instead.

 

I am contemplating if drilling a (very) carefully placed 1/2" hole at each tap spot is beneficial to clean the cooling jackets (and then install a threaded plug) wouldn't be helpful.

 

Honestly, I've been wondering why my stock N42/N47 motor doesn't make more power at 15 psi with new HG, rebuilt top end and isky cam than getting the cooling system better.

[WizardBlack]

Ok so with all of this discussion, I think I am going to jump off this cliff and have the cylinderhead done from #2-#6. I don't think #1 is really an issue as it is right at that large hole for the thermostat housing. I have completed #5 & 6, and was intending on doing # 3 but between 3 & 4 is difficult to do. I have already invested about 300 in what I have done, but the union T I used (swedgelock) is to big to get between 3 & 4 so a redesign is in order.

I will get the 1/4 NPT fittings, do the intake clearancing for 3-4 use the A/N fittings and run the tubes to a common tube 1/2" but instead of using fittings have each tibe TIG welded to the common return pipe. I use a local welder here Master Craft Welding to do the work. This guys TIG welding is the best I have ever seen, very percise and very clean. I have him do the work I want to look good and be strong. I have already bought all of the -6 45 1/4" NPT fittings. Getting around the head stud between 3-4 is going to be the tough one, but I think it is doable. And just to make sure where it needs to go, I have a good door stopper P90 head I will section to make sure of the fitting locations.

Why is it that every time I get involved in this stuff it starts costing me lots of money LOL, but its only money right? Anyway this is just part of the crap I am working on right now, and since I just dropped close to 4 grand on components for a race head what the hell!

 

I am not sure that doing five of the six is a good way to go. I believe we talked about that earlier in the thread and Tony made some great comments on it. If you did all of them, you still have a flow bias, no? Someone who remembers their engineering better than I could confirm, but you could very well increase the discrepancy.

[WizardBlack]

By the way, post 13 of my build thread includes my notes on how it affects bleeding the cooling system and some other minor things if anyone intends to do it.

 

Build thread

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V

[Zmanco]

So I've got the motor up and running with the #5/#6 feeding into the bottom of the thermostat housing on my turbo motor. Unfortunately the motor is somewhat new to me (more in a moment) so I don't really have a baseline to compare, but I've noticed that the temps seem to swing up and down more than my old NA motor.

 

The new motor has a P54 turbo stock bottom end (untouched), shaved P90 head carried over from the NA engine, Schneider turbo cam (2nd level), stock exhaust manifold and T3/T4 turbo with 3" exhaust. Basically the only new parts on the "new" engine are the block and internals, timing cover, thermostat housing, injectors, exhaust manifold and turbo. The head, water pump, thermostat, temp sensors, and intake manifold are all carried over from the old motor.

 

As an experiment I tried routing the 5/6 coolant into the water return on the passenger side of block to see if the temp swings I'm seeing were more of an anomaly due to dumping hot water right where the sensors are located. Turns out it didn't make any difference that I could tell driven on the street, so I moved it back.

 

The old block was an N42 which without the siamesed cylinder walls is said to have better cooling. The new block is a P54.

 

Any thoughts why the temps are different with this motor even when driven with a light steady foot, such as cruising on the highway at 65 mph? Ex. old motor temps stayed pretty close to 180, maybe rising a few degrees on a warm day, but moving slowly and never more than 2 or 3 degrees at most. Now the standard cruising temp, even on a cool day, is 185-188 and the temps will sometimes surge up to 193-195. Again this is when cruising off boost with light throttle and steady highway speeds. Could the switch from N42 to P54 block be the reason? Oh, and I have not yet put the splash guard back on, but in the past it never made any measurable difference on the street.

[Tony D]

What is the instrumentation?

If you are getting superheated steam pockets back in 5/6 and they now have a direct way to get to the sensor and blast across it...instead of sitting back there festering, or coming back into solution on the way to the front of the block.

[Zmanco]

What is the instrumentation?

If you are getting superheated steam pockets back in 5/6 and they now have a direct way to get to the sensor and blast across it...instead of sitting back there festering, or coming back into solution on the way to the front of the block.

Measurement is via the stock sensor/gauge as well as megasquirt. The MS sensor is mounted in the factory turbo thermostat housing next to the factory sensor. They are pretty much in sync with each other.

 

I thought that the temp swings were due to what you described as well so I tried an experiment where I routed the 5/6 hose to the water inlet on the passenger side of the block. I drove around like that for a few days and it didn't seem to be any different in terms of the temp swings and elevated temp. I will add that this was not a controlled test in that I just drove the car, not on the same routes or under the same conditions. But there was enough variety (city streets and highway) and the temps were similar enough that I think it was still a valid test.

[rossman]

Measurement is via the stock sensor/gauge as well as megasquirt. The MS sensor is mounted in the factory turbo thermostat housing next to the factory sensor. They are pretty much in sync with each other.

 

I thought that the temp swings were due to what you described as well so I tried an experiment where I routed the 5/6 hose to the water inlet on the passenger side of the block. I drove around like that for a few days and it didn't seem to be any different in terms of the temp swings and elevated temp. I will add that this was not a controlled test in that I just drove the car, not on the same routes or under the same conditions. But there was enough variety (city streets and highway) and the temps were similar enough that I think it was still a valid test.

 

Are you running an intercooler? Maybe it is blocking air across the radiator.

[Tony D]

I would do more investigation, but I think you may be tracking instrument anomalies more than anything really substantiative.

 

Are you running a 160 thermostat, or higher? I noticed more swings in temperature when running the 180 and 190 thermostats, than when I switched to a 160. I chalked it up to the hotter thermostats allowing spot boiling, whereas the 160's kept everything in the liquid format. Truthfully with the 160 in there, I have issues keeping the temperature high enough at idle to stay out of the normal range of the cold start loop (but since it's MS and can disable that bin!)

 

You may simply be running too hot and boiling in spots no matter what. What is your coolant mix, what pressure on the cap, etc etc etc...

 

There are way too many variables to note the anomaly without checking all the basics first. Way to many to say it's from venting of the 5/6 head area as well, and by the repositioning showing no effect, it shows (to me at least) that it's something else entirely causing it.

[Zmanco]

Are you running an intercooler? Maybe it is blocking air across the radiator.

I am and it's mounted a few inches in front of the radiator, not flush with it. I wonder if there is turbulence between the two which is reducing the airflow?

 

TonyD, what you're saying is indeed in the back of my mind. I don't want to get too carried away with one datapoint that wasn't even obtained with any sort of real control. I was just throwing it out there to see if perhaps someone else had seen this and tracked it down. Right now the weather has cooled a lot and so it's hard to stress the cooling system without track time. I'm just driving it and since I'm not having any overheating issues, am not going to worry about until it warms up again.

 

BTW, I am running a Nissan 180 t-stat. Just to be sure, I replaced it but there was no change.

[Tony D]

Replaced with another 180?

My focus was that when I ran 180's I was getting steam with the standard cap.

 

There exists two possibilities:

1) Put a 24psi cap on and see what the temperature does.

2) Put a 160F Thermostat in and see if you still get swings.

 

If it goes away, in either case, then you know what is causing it. If it doesn't go away with the 160, then install the 24# cap with the 160 and see what happens.

 

My bet is there is a hotspot in the cooling system causing it, and the only way to fix it is to either run more static pressure, or cool it down below the boiling point.

 

I run 160F thermostats because I'm not hung up on Adibiatic Theory, and figure if the oil is at proper temperature (at least 180F) then I'm fine. It keeps the radiated heat within the engine bay much lower, and that means rubber and plastic lasts longer. Good nuff fer me.

 

Heck, I could put a 30psi cap and run 215F thermostats and be 'really thermally efficient' but I'm thinking other problems would creep up along the way. In a tropical environment Nissan Specs a 72C thermostat, so I'm not that far off a standard fittment for my situation anyway!

[datman]

On this subject I finally got around to sorting an old p90 out for modification. I commissioned a local company to make certain changes to the head.

Stage 1 will be to strip it and acid dip it to clean out the internal water ways.

Stage 2 will be to modify the combustion chamber (pics to follow)

Stage 3 will be to tap into the water jacket for each chamber and route to a common manifold.

Finally the combustion chamber will be ceramic coated.

I'm looking forward to comparing the head to the standard p90 I'm running right now.

The combustion chamber mod looks to be different from any I have seen on here so far. I will post up pictures as they send them to me.

I'd like to thank the guy that cut the heads into cross sections, the pictures have been of great help.

[RTz]

Finally the combustion chamber will be ceramic coated.

 

While you're at it, you may want to coat the exhaust ports.

[X64v]

I'm no longer running a heater so I was able route the return line much nicer. It's still the same to the T, but now:

 

 

 

I've got right at 10,000 miles on the bypass ports right now. I have no proof that they've helped, but I do know they're not hurting a thing, I've found zero adverse effects from this.

[datman]

While you're at it, you may want to coat the exhaust ports.

 

Good idea, Thanks

[B00STDZ]

OK, Here's what I have used and seen in practice. None of this is my original idea. My friend Oz has been the source for much of this information. So first is the water pump, I use the LD28 water pump which does have a larger impeller. The only modification you have to make it to trim roughly 1/8 - 1/4 inch off the leading edge where the pump mounts to the timing chain cover. I have illustrated this in the below pictures. The LD28 pump is Nissan part number 21010-17SY7. Do not go to a local parts store to buy the LD28 pump. You will just get a regular L28E pump and not the one with the larger impeller. For some reason they don't recognize a difference. I also should say that I have never noticed an improvement with the larger pump. I know the larger impeller moves more water but since I have never had a cooling system issue I can't say for sure that it helped my application. Either way, I think it's a good idea and the principle is sound.

 

I have not done this modification but my friend Oz did this on his Bonneville 280ZX. Basically he drilled and tapped three ports above the exhaust on what looks like cylinder 3, 5 and 6. He joined the three ports into a single manifold then had a separate inlet back into the radiator bypassing the thermostat. His application did not use a thermostat so that would be something to consider for a street application. Even under extreme boost and and environmental conditions, the Bonneville L28 setup never had any cooling system or detonation problems he was aware of. There are many other factors that helped but these modifications were key. The picture I enclosed shows the engine in 1991 trim so things are a little aged but you get the idea. I hope this helps.

 

 

 

 

 

 

Interesting points made about the ld28 water pump being larger...

 

These past few days I have been eyeing the electric water pump that msa sells wondering if it might possibly flow more than the ld28 pump... and keep the head cooler at idle. Seeing that this pump is electric, it wont be dependent on high rpm's to turn fast...

 

http://www.thezstore.com/page/TZS/PROD/PCLC06/16-7025

The pump im referring to...