Head cooling on cylinder #5 - solutions?

[Tony D]

"The early 240s just weren't designed with air conditioning and real hot weather in mind. As long as the car was moving and getting decent airflow across the radiator, the car did okay."

 

Time for subtle rephrasing:

"The early NORTH AMERICAN MARKET LEFT HAND DRIVE 240s just weren't designed with air conditioning and real hot weather in mind. As long as the car was moving and getting decent airflow across the radiator, the car did okay."

 

They were severely decontented, with absence of splash pan, Full Radiator Shroud or the higher BTU radiator that was put into the RHD Vehicles that came with A/C from the factory (an in-dash unit, just like the 260's and 280Z's had!) Being that the cars were marketed and sold in Okinawa, it makes Houston feel like Boston in February. The lack of Aerosols there (unlike Houston) will add to thermal layering at radiator height. Instead of monitoring ambient temperature, put some K thermocouples in the radiator air stream, and under the hood (or monitor your ECU for inlet air temperature) --- I think you will be surprised what you find, but from my testing the temps there aren't that much different than ambient. Go to West Texas and NM where the skies are a deep blue (and not light blue/grey) and you will see a marked increase in thermal layer temperature into the radiator.

 

We ran at Reno LeMons and blistered the race as the leaders for that time... till our harmonic balancer took a dump and the engine burned itself down. And that was a stock junkyard engine, with a junkyard three core radiator, running a Kragen Thermostat for a 1962 Chevrolet Biscayne 327 (160F) and a stock new water pump. I think we had an old 16# cap on there

 

We didn't get anywhere near overheating, and were running a 3.54 at the time with a four speed. Plans are for a 3.9. With the specific output of a stock Z engine there is plenty of margin for it.---if you are having problems, you're missing something big, or mistuning severely. We consume 11 gallons in 2 hours, and do a driver change, and the heating has never been an issue for Mr. Hanky, or his successor Hanky Too (which inherited his heart from Hanky 1)

 

This discussion was really revolving around cars putting out at LEAST 2X what your N/A racer is making, and in many cases 3X that amount. Anything below 300HP to the rear wheels should not have any issues using bone stock parts. If you are detonating, it's not from cooling, but likely more misapplication of parts or lack of attention to assembly detail. This stuff will kill you. For sure, below 200HP the stock stuff should have no issues. We run NO fan, and pray there aren't any stops or slows---as long as we are moving at 30mph, the needle doesn't budge. Why no fan? Because it tends to wreck radiators when you hit something, and we figured 'why risk the failure point' --- though for some track testing it gets reinstalled with the full stock Datsun Shroud. Trying to rethink engineers with millions of yen to back them, and hundreds of hours on the dyno to test sometimes is a foolish escapade.

 

If you are running endurance events differential cooling will hit you as the next failure point after you get the cooling system up to snuff.

[ozconnection]

I was looking at some stuff and saw this head with a temperature sensor boss located between cylinders 5 and 6.

 

Did Nissan already know something about the hot spot in this area? They could have put the sensor location anywhere along the head, why here specifically?

 

This particular engine doesn't have the temp. sensor screwed in. Does anyone know why?

 

[Noddle]

My N47 (closed chamber) head has this as well, I was going to use it for my knock sensor, but under further investigation, it seems it would be to noisy

 

http://forums.hybridz.org/attachment.php?attachmentid=20235&d=1264413284

 

Nigel

[Tony D]

This is particular to North American Emissions Regulations. This is a hotter point than the thermostat mounted sensor. It will run 10C hotter depending on loading of the engine. This puts the car in closed loop quicker, meaning less pollution.

 

It comes in handy for people with High Horsepower cars as they can benefit from sensing the hotter point.

 

In practical experience and application, I have seen no real difference in operation using either point. The sensor has the same curve / response as the one in the thermostat.

 

I use it on my wife's turbo car, because it takes me out of cold start loop faster, and enables O2 correction that much quicker. It results in slightly better fuel economy as a result.

[ozconnection]

Ok, cool.

[ozconnection]

My N47 (closed chamber) head has this as well, I was going to use it for my knock sensor, but under further investigation, it seems it would be to noisy

 

http://forums.hybridz.org/attachment.php?attachmentid=20235&d=1264413284

 

Nigel

 

Yeah, when I look at the location of the factory unit on my L20A ET's, it's quite low on the block. All depends now on what you use to do the detecting.

[hoov100]

Alright, so what I gather out of this thread, the street fix is pretty much tap the coolant passages at 5&6 in the head and run it to the lower radiator hose?

[Tony D]

Alright, so what I gather out of this thread, the street fix is pretty much tap the coolant passages at 5&6 in the head and run it to the lower radiator hose?

 

No, to the thermostat housing. Look at the diagram provided earlier. Let's not degrade this into 'ZCar.com Generalizations' type answers, it's been far to specific in the discussion thusfar to let that happen.

[hoov100]

No, to the thermostat housing. Look at the diagram provided earlier. Let's not degrade this into 'ZCar.com Generalizations' type answers, it's been far to specific in the discussion thusfar to let that happen.

 

Alright! just making sure I got my info strait.

 

 

 

 

 

 

 

(please don't kill me!)

[angel]

We have used bleeder tanks with great results tho.Specially on turbo cars

[Oddmanout84]

I have been pouring over this thread for a while now, and plan to tap bypasses into my spare P90 head. That was a lot of information! Oddly, I don't remember seeing anything about it in the "how to modify your datsun OHC engine" book. I wonder why...

 

Anyway, I remember seeing some posts from people looking to source the higher flow LD28 coolant pump earlier, but I don't remember seeing if anyone found a source. I looked it up and found them on Rockauto.com. I've ordered some stuff from them before, so they're legit. Just not sure if there's any differences between their remanufactured/new products and the stock Nissan part in terms of reliability.

 

http://www.rockauto.com/catalog/raframecatalog.php?carcode=1211230&parttype=2208&a=FRc1211230k475236

Edited March 23, 2010 by Oddmanout84

[Tony D]

I have been pouring over this thread for a while now, and plan to tap bypasses into my spare P90 head. That was a lot of information! Oddly, I don't remember seeing anything about it in the "how to modify your datsun OHC engine" book. I wonder why...

 

 

There is a REAL simple answer for that, which you won't like to hear:

 

"You weren't looking for it."

 

ozconnection can testify, this past Sunday, I stood in his dining room with the VERY book you mention and revealed where I got the information, and at that moment it all became obvious. It's there, right in front of you. It was there in front of him as well and he didn't find it in the book till I showed him the way. Unfortunately many people are very one-dimensional when it comes to learning. They think you just absorb what someone tells you.

 

That, my friend, is a very big misconception!

 

Understand something else, Frank Honsowetz didn't do anything to speak of in that book. The guy compiled what the people on the Electramotive (and other racing teams) chose to tell him. At the time the book was written, this engine was still in competition, competition which would add to Electramotive's headaches on-track. Like any professional race team they told him in the most general terms what they did. And while they told him a lot, they didn't tell him everything.

 

But today, you can't carry a cel phone onto the production floor at Cosworth. Most places have you check any electronic gear up front before you go into the workshop. To paraphrase you "I wonder why..."

 

Some people laugh at guys who buy Playboy for 'The Articles' when we all know it for the photos. But here you only read the words... Go look again and make the Homer Noises when you find what was there, looking at you all the time, right in the face, that you glossed over countless times before never LOOKING, never SEEING. You read, but you did not SEE.

 

I hope that last bit was not to Zen for ya!

[BRAAP]

There is a LOT of info in the book if you read between the lines. Helps to have some mechanical engine building/design background from which to "see" that info...

[zxtman]

... in other words, look closely at the photos. It is shown in more than one occasion and in different configurations.

[Oddmanout84]

 

Some people laugh at guys who buy Playboy for 'The Articles' when we all know it for the photos. But here you only read the words... Go look again and make the Homer Noises when you find what was there, looking at you all the time, right in the face, that you glossed over countless times before never LOOKING, never SEEING. You read, but you did not SEE.

 

I hope that last bit was not to Zen for ya!

 

Oh, I understood. And you're absolutely right. I "read too far into it". Disturbingly often its the most obvious things that are right in front of our faces which we fail to see. Well you know that internet saying; "When you see it, you'll sh*t brix." ? I did.

 

That'll sure teach me for reading!

Edited March 24, 2010 by Oddmanout84

[Tony D]

The neat thing is now talking with some of the guys who worked on those builds and getting quantifiable numbers from them as to the results they achieved.

 

Remember, this was for a very high specific output engine, 333HP per liter +

 

Most people will not need this level of preparation, and likely those who are running 1/6 of that horsepower level will start to think of this as some magic bullet, curing some 'inherent design flaw' which is not the case at all.

 

I've said it elsewhere, if you are overheating on an 85-90 degree day in Georgia or Florida, you got something seriously screwed up with your cooling system! Fix THAT before going to something that wasn't meant nor required for that horsepower level.

 

insurance is one thing, but you don't insure your tin shed for a million bucks just in case the wind blows it away. Putting these mods on a car making 200HP is kinda overkill, and likely any heating problems they are having in that application is related to overlooking basics of a good cooling system.

[Oddmanout84]

The neat thing is now talking with some of the guys who worked on those builds and getting quantifiable numbers from them as to the results they achieved.

 

Remember, this was for a very high specific output engine, 333HP per liter +

 

Most people will not need this level of preparation, and likely those who are running 1/6 of that horsepower level will start to think of this as some magic bullet, curing some 'inherent design flaw' which is not the case at all.

 

I've said it elsewhere, if you are overheating on an 85-90 degree day in Georgia or Florida, you got something seriously screwed up with your cooling system! Fix THAT before going to something that wasn't meant nor required for that horsepower level.

 

insurance is one thing, but you don't insure your tin shed for a million bucks just in case the wind blows it away. Putting these mods on a car making 200HP is kinda overkill, and likely any heating problems they are having in that application is related to overlooking basics of a good cooling system.

 

Well, I highly doubt I'll ever go as far as the engines in the book. It would be overkill for my car which is mostly a fun street driver. However, I do want to track it down the road at Limerock, once I'm ready. At most I wanted to do the simple plumbing similar to what others have done in this thread. I've only had my L28 turbo motor in my Z since last fall. Its been driven in pretty much nothing but 60*F and below weather. Engine was blueprinted, but pretty much stock rebuilt by the guy who owned it before my friend, which was in turn sold to me. Had about 4000 miles on the rebuild before I got it. Stock turbo as well, non-watercooled center section. Radiator is aluminum with an electric fan. The temp gauge stays well in the middle when moving forward, but if I idle in traffic for a few minutes it quickly runs up to 250 on the gauge. I'd considered the gauge was just getting old and inaccurate, but the temp relay controlling the fan kicks on right about where it should according to the gauge. The other day it was about 60* out and I idled the car long enough to seafoam the engine. Upon shut-down it shot out quite a fair amount of boiling coolant into the overflow tank, enough to fill it. I've always tried to burp the system correctly when I fill it, but maybe I'm missing something... I've been running either 50/50 or diluted 50/50 with water wetter in both. It just seemed puzzling that it would climb so fast in colder weather, and made me wonder how this summer was going to be. If its having this much trouble at idle I can't imagine trying to push it farther (than what I currently run) without some serious fixes.

 

Just letting you know where I'm coming from.

[Oddmanout84]

Well, I highly doubt I'll ever go as far as the engines in the book. It would be overkill for my car which is mostly a fun street driver. However, I do want to track it down the road at Limerock, once I'm ready. At most I wanted to do the simple plumbing similar to what others have done in this thread. I've only had my L28 turbo motor in my Z since last fall. Its been driven in pretty much nothing but 60*F and below weather. Engine was blueprinted, but pretty much stock rebuilt by the guy who owned it before my friend, which was in turn sold to me. Had about 4000 miles on the rebuild before I got it. Stock turbo as well, non-watercooled center section. Radiator is aluminum with an electric fan. The temp gauge stays well in the middle when moving forward, but if I idle in traffic for a few minutes it quickly runs up to 250 on the gauge. I'd considered the gauge was just getting old and inaccurate, but the temp relay controlling the fan kicks on right about where it should according to the gauge. The other day it was about 60* out and I idled the car long enough to seafoam the engine. Upon shut-down it shot out quite a fair amount of boiling coolant into the overflow tank, enough to fill it. I've always tried to burp the system correctly when I fill it, but maybe I'm missing something... I've been running either 50/50 or diluted 50/50 with water wetter in both. It just seemed puzzling that it would climb so fast in colder weather, and made me wonder how this summer was going to be. If its having this much trouble at idle I can't imagine trying to push it farther (than what I currently run) without some serious fixes.

 

Edit: I hope this doesn't make it sound like I'm trying to hijack this thread and ask for help on my own issues, just letting you know where I'm coming from. With my current equipment especially, my heat issue seems odd. Especially since this car used to never go above 3/4 temp gauge in hot socal weather with a stock radiator and NA L28.

[Oddmanout84]

why the heck did it double post when I tried to edit...

[Tony D]

I've run a 350HP+ Turbocharged 240Z in SoCal Deserts since moving here in 1989 and with a three core radiator have NEVER had cooling problems. Understand where "I'm coming from:" If there is a problem that is making you overheat on a basically stock turbo fix that issue first before moving on to this modification series.

 

Jumping to this as some "miracle cure" for an engine which should NEVER overheat is NOT the right way to go! This is akin to putting a band-aid on an aortic hemmorage caused by a needle puncture. You stop that little irritation on the surface, but inside, you're falling to hell quickly!

 

The troubleshooting procedures for a car doing what you say yours is doing is clear cut. Putting this modification will NOT solve the issue.

 

Identify, Verify, Isolate, Repair, Operationally Check

 

Given what you say, my SWAG is your fan is a POS and not doing the job, and/or the radiator cap has taken a crap/is leaking. My electric fan will kick on at 170, cool the engine to 155 and shut back off in the scenario you describe. I run cooler at 65 than I do at 55. I run the same temperature from 30mph in 5th gear to 55, where I get a little bit cooler. Up to about 100mph when it starts adding some heat to the 175-185 F range into the radiator. Old 1989 vintage MSA 3-Core Radiator.

 

People tend to put a lot of stuff in their car thinking they are doing something better than stock, when in fact its not very well thought out or engineered nearly as well as the OEM piece removed.

Edited April 12, 2010 by Tony D