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Head cooling on cylinder #5 - solutions?


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  I assume you did try to source the LD pump in Australia, I saw a thread and you mentioned you got it from Japan (?)

My thoughts on the Summary:   - The path of coolant through the L engines results in the rear of the head receiving the hottest coolant having stagnated water flow, insufficient for the he

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Next I will try a couple of p79s on that same block.......one pristine and one that likely rarely saw anything than rusty water.

I'm pretty sure the was talk of being able to see (or possibly chip at) the flashing via the plugs on the top of the heads. Perhaps a comparison of your pristine and crusty head might be possible that way?

 

Endoscopes are getting pretty cheap on Ebay...

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  • 1 year later...

Reviving this thread to show what I came up with, So far 100 miles of testing, it seems to be doing it's job, have had zero spark knock so far, t3/t4, 440cc injectors, 26 degrees advancement at full boost so far

 

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That looks like a nice job of tapping the head and a nice way of running all the lines together and routing back to the thermostat housing, using some existing hardware for the manifold.   One dumb question though - how did you get the air out of it,since the water manifold is sitting higher than your fill point?  Is there a bleeder/fill point that isn't visible in the pics?

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That looks like a nice job of tapping the head and a nice way of running all the lines together and routing back to the thermostat housing, using some existing hardware for the manifold.   One dumb question though - how did you get the air out of it,since the water manifold is sitting higher than your fill point?  Is there a bleeder/fill point that isn't visible in the pics?

Thank you.

 

I worried about this same dilemma, i initially mocked it up with the head on head stands on my work bench, when i installed it is when i realized just how high in the cooling system it is. The top of the rail has a port that I tapped for a pipe plug, it's originally for a FPR, so I opened that up, and bled the cooling system with a bleeding funnel and an extension which brought the funnel to the highest point in the cooling system.

 

Once i did that, t-stat opened and all that, between the water movement from the water pump and the pressurized system, it continues to push coolant into the rail and through the thermostat housing.

 

I have verified several times just for my own redundancy and it still pushes coolant out every time i crack the bleeder plug.

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Thank you.

 

I worried about this same dilemma, i initially mocked it up with the head on head stands on my work bench, when i installed it is when i realized just how high in the cooling system it is. The top of the rail has a port that I tapped for a pipe plug, it's originally for a FPR, so I opened that up, and bled the cooling system with a bleeding funnel and an extension which brought the funnel to the highest point in the cooling system.

 

Once i did that, t-stat opened and all that, between the water movement from the water pump and the pressurized system, it continues to push coolant into the rail and through the thermostat housing.

 

I have verified several times just for my own redundancy and it still pushes coolant out every time i crack the bleeder plug.

Awesome - that was pretty much what I was going to suggest if you hadn't already done it!

 

I figured it was a good thing to make clear in the event that others want to reproduce what you've done.

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How come your using fuel hose and not heater hose?

 

it's what i had in bulk at home, been using it for years with cooling system hoses, no issues.

 

When you say this mod has been effective - are you saying that you couldn't run this much boost or timing before this mod ?

 

technically i said it seems to be doing it's job lol. in that aspect, coolant is consistently flowing into the rail and exiting to the t-stat housing.

 

However, I do not have any dyno sheet to prove before and after results. I've ran 18psi consistently on my old N42 setup, but could never get more than 9 degrees max advance under full load with 93 pump gas before i would experience light spark knock.

 

I'm sure a lot has to do with the fact that this is a p90 head with a better combustion chamber design for boost, also lower compression, and on top of that, i've lost about 3-4ccs per combustion chamber from the valve de-shroud, so according to my calculations, i should be around the 7:1 compression range.

 

Given that i've read all 25 pages of this thread, in theory, it should make a noticeable difference compared to not doing this mod at all. Also, setting this entire thing up cost me under $50, so it was really just time, figured I would give it a try and see how it works out.

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Awesome - that was pretty much what I was going to suggest if you hadn't already done it!

 

I figured it was a good thing to make clear in the event that others want to reproduce what you've done.

Yes it would be relatively easy to make on your own for anyone who would like to try this. you would obviously need a decent drill bit set, 1/4" NPT and a 1/8" NPT tap. 5 1/8"NPT to 3/8" barb fittings, a few pipe plugs, 4 1/4"npt to 1/8"npt adapter bushings, and 2 straight 1/8"npt to 3/8" barb fittings.

 

From there, pipe thread sealant, EFI hose clamps and bulk hose

 

I may also explore the idea of a higher pressure cap as some have done in this thread.

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it's what i had in bulk at home, been using it for years with cooling system hoses, no issues.

 

 

 

technically i said it seems to be doing it's job lol. in that aspect, coolant is consistently flowing into the rail and exiting to the t-stat housing.

However, I do not have any dyno sheet to prove before and after results. I've ran 18psi consistently on my old N42 setup, but could never get more than 9 degrees max advance under full load with 93 pump gas before i would experience light spark knock.

I'm sure a lot has to do with the fact that this is a p90 head with a better combustion chamber design for boost, also lower compression, and on top of that, i've lost about 3-4ccs per combustion chamber from the valve de-shroud, so according to my calculations, i should be around the 7:1 compression range.

Given that i've read all 25 pages of this thread, in theory, it should make a noticeable difference compared to not doing this mod at all. Also, setting this entire thing up cost me under $50, so it was really just time, figured I would give it a try and see how it works out.

 

 

I was hoping to see a more direct comparison . I plan on doing this on my mn47 head .

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read through the first few pages of this thread and see if your application applies. I do alot of highway running with mine, hard highway running, it's not my daily, so when it's being used, its being abused. I saw it as a necessary modification, I also plan on using water/meth, running more boost and more timing, i figured for the cost factor it was a cheap investment.

 

Are you going to be running carbs or megasquirt? You could see how much timing you can give it before you get spark knock, then do this mod, and see if it increases your threshold. I would imagine it would.

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Without going back to your original head and set up and only making only this one change it's impossible to know how much this is helping.

 

One thing I would suggest is to increase the size of the hose and fittings from the manifold to the thermostat housing.  The setup you currently have has 5 hoses coming in and one going out, all the same size.  The hose between the manifold and thermostat housing is a restriction to flow. There are no guarantees it will help but it should maximize flow thru the system and improve cooling in the back of the head.

 

it's what i had in bulk at home, been using it for years with cooling system hoses, no issues.

 

 

technically i said it seems to be doing it's job lol. in that aspect, coolant is consistently flowing into the rail and exiting to the t-stat housing.

However, I do not have any dyno sheet to prove before and after results. I've ran 18psi consistently on my old N42 setup, but could never get more than 9 degrees max advance under full load with 93 pump gas before i would experience light spark knock.

I'm sure a lot has to do with the fact that this is a p90 head with a better combustion chamber design for boost, also lower compression, and on top of that, i've lost about 3-4ccs per combustion chamber from the valve de-shroud, so according to my calculations, i should be around the 7:1 compression range.

Given that i've read all 25 pages of this thread, in theory, it should make a noticeable difference compared to not doing this mod at all. Also, setting this entire thing up cost me under $50, so it was really just time, figured I would give it a try and see how it works out.

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Without going back to your original head and set up and only making only this one change it's impossible to know how much this is helping.

 

One thing I would suggest is to increase the size of the hose and fittings from the manifold to the thermostat housing.  The setup you currently have has 5 hoses coming in and one going out, all the same size.  The hose between the manifold and thermostat housing is a restriction to flow. There are no guarantees it will help but it should maximize flow thru the system and improve cooling in the back of the head.

Good point. I'm just happy to have this money pit running after 3 months down lol. I will more than likely make such a revision down the line

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For what it's worth, If anyone is uncomfortable drilling into their own head without proper measurements, and would like something as bolt in as possible, I have a spare junk cylinder head I can use to mock up and sort of produce these in small numbers if there is any interest. I could make a drilling template to tape to the head, provide a drilled and tapped rail and fittings, all you would have to do is drill the holes in the head, tap them, and put everything together.

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The internal path to the thermostat is still there, right?  I thought that the point of this was to removed dead flow zones, hot spots.  So, total flow is maintained, but there's a side current introduced.

 

Seems like flow control valves in each port might help, to balance flow.  To avoid creating a dead zone somewhere else..  

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Yea there is enough information within this thread for anyone toying the idea, anyone halfway competent with a drill and taps should be able to tackle this fairly easily. I might talk my buddy into doing this mod on his 240z turbo, if he does, i'll do a timing map before and after and see if it made any significant threshold increase.

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