A known cooling mod?

[AliK]

Came across this (somewhere) while looking for something else. I believe it’s a “well known” mod to sort out cyl6 getting hotter than the rest. Apparently you have to also block some water hole somewhere towards the front of the block.

Is anyone aware of this and done it?

 

[jonbills]

 

[jonbills]

The thing they say you need to block is the bypass in the front of the block, which just returns coolant to the pump when the thermostat and heater are closed (to prevent cavitation).
Its where my new engine leaked because its not present on the diesel block but is on the petrol head.
I return the flow from #5/#6 to the thermostat lower so it doesn't bypass it.

 

[toopy]

Any particular reason for taking the feed pipe round the head and not over the inlet manifold?

 

[jonbills]

Any particular reason for taking the feed pipe round the head and not over the inlet manifold?

I think I may have originally intended to plumb it into the water pump return, and then changed my mind, so no good reason now.

 

[Fairlineguy]

Those front cam lobes look dry of oil or is it just the picture

 

[jonbills]

Those front cam lobes look dry of oil or is it just the picture

Mine? I hope its just the picture

 

[SeanDezart]

Came across this (somewhere) while looking for something else. I believe it’s a “well known” mod to sort out cyl6 getting hotter than the rest.

Why would no.6 get hotter when running Bosch EFi ?

 

[jonbills]

Why would no.6 get hotter when running Bosch EFi ?

I believe the suggestion is that there is poor coolant flow in the head at 5 and 6.

 

[SeanDezart]

So, why his and not ours ? Sounds like the original problem* should be rectified before throwing fixes at it !

*specific to his own engine.

 

[jonbills]

So, why his and not ours ? Sounds like the original problem* should be rectified before throwing fixes at it !

*specific to his own engine.

I not sure what 'his' and 'ours' refer to, but it is said to be common to all L gata heads. I don't know if it is true, but the mod is easy and hasn't done any harm on my engine.

 

[SeanDezart]

I not sure what 'his' and 'ours' refer to, but it is said to be common to all L gata heads. I don't know if it is true, but the mod is easy and hasn't done any harm on my engine.

Sorry, thought that was clear enough - here it is again : So why his ENGINE and not our (s) ENGINE ?

It is "said" ? Who started that rumour ? Why didn't Nissan themselves do this ? Why don't race engines have this whose temperatures far exceed our road cars ?

I'm not knocking the idea - it simply looks like a solution for symptoms without addressing the orginal problem of an overheating end of cylinder block....which is not inevitable nor that common !

 

[zbloke]

Is anyone aware of this and done it?

Nissan did it on the L6 FIA heads.........slightly more elegantly then the one in the first pic

https://forums.hybridz.org/topic/117848-fia-cylinder-head-on-race-car-in-us-more-info/

 

[jonbills]

and https://forums.hybridz.org/topic/59029-head-cooling-on-cylinder-5-solutions/

 

[SeanDezart]

"No. It's got an Oppama modified E31 head."

The 'Safari' head you mean ?

 

[SeanDezart]

and https://forums.hybridz.org/topic/59029-head-cooling-on-cylinder-5-solutions/

Quotes :

"I've heard several times that #5 is problematic due to water flow issues, and johnc posted the following in that thread:

Had that happen to the cylinder 5 in the ROD but the seat blew apart and I found most of it in the intake manifold. The cause was very slight detonation in that cylinder. What caused the detonation was a localized hot spot in the cylinder. This is a well known issue for high cylinder pressure L6 engines.

What cured the problem for my car was increasing the cooling system pressure to 28 psi to reduce nucleate boiling at that point."

"My suspicion is that the "#5 issue" is more due to eddy currents or cavitation caused by the flow path inside the head. That end of the head gets the coolest water, so I don't think it's an issue of the water getting progressively hotter from having to pass over all the chambers from back to front."

I've not had any problems, ever during +30yrs....I can't merely be 'lucky' !

 

[zbloke]

I've not had any problems, ever during +30yrs....I can't merely be 'lucky' !

You've probably not had an L6 running high cylinder pressures Monsieur

I believe John Coffey's Sunbelt L6 was in the region of 13:1/13.5:1 static compression

 

[Alphabettispaghetti]

This place makes me chuckle sometimes.

 

[SeanDezart]

You've probably not had an L6 running high cylinder pressures Monsieur

I believe John Coffey's Sunbelt L6 was in the region of 13:1/13.5:1 static compression

Nope but going back to the original photo of a 280Z....do you suspect it of having high cylinder pressures too Mister ?

 

[zbloke]

Nope but going back to the original photo of a 280Z....do you suspect it of having high cylinder pressures too Mister ?

I have absolutely no idea

And guessing whether it has or hasn't won't help