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Head cooling on cylinder #5 - solutions?


TimZ

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sorry i back tracked and saw how many other motors did that. i going to try to make one and put pictures up when i am done. any suggestions. i am going to use 8an fittings and a 1.25" main runner also am considering using a Meziere Inline Thermostat Assemblie. tell me if you think it will work.

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has anyone ever thought about capping the upper t stat housing and making a coolant manifold similar to the one on the os giken head? drill above each cylinder and at the end of the manifold install a thermostat. would this work.

 

Yes, it's been done, photos are in the archives.

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  • 3 months later...

At long last more to report. The 'loop the hose when the heater is bypassed' was finally tested today.

Long and short of the testing was that with the back of the head looped straight to the pump inlet (like some do when bypassing the heater core---instead of blocking it off)the following results were obtained using the Nissan CHT as read through the Nissan ECU.

 

With a 25hp load on the engine running 4500rpms and the hose looped and open, CHT=220F

With a 25hp load on the engine running 4500rpms and the hose BLOCKED CLOSED, CHT=170F

 

Results obtained on a Superflow 900 series Dyno, with the thermostatic water valve set to maintain 160F water.

The tests were stopped at 4500rpms as the suction hose on the dyno would start collapsing above that point.

This would be similar to stock gearing at 80+ mph or thereabouts. What we wanted to see was how high we could go before the 'open hose' started to rise in temperature, but even with a collapsed hose above 5000rpms we could not get CHT above 170, whereas with the hose open and flowing to the pump inlet (which you think would help prevent the hose collapsing...) the temperature started to rise even more above 4500, so we figured stopping the test there was the best comparison. Results at 3000rpms were almost identical when the engine was 'stabilized' --- that is run in steady-state load for several minutes.

 

Yes, we were running the engine for several minutes at a time checking load points, etc. Let temperatures stabilize then run to a higher number. So nice not to have to stop and let everything cool down! Mmmmmm, engine dyno! Gaaarrrrggggh! :D

 

Later the engine was put through...uh..."More Rigorous Testing" Wallpaper, Anyone?

 

post-380-004996900 1293782273_thumb.jpg

 

post-380-068157500 1293782224_thumb.jpg

 

post-380-080266800 1293782332_thumb.jpg

 

post-380-058941800 1293782378_thumb.jpg

Look, you can see Jeff almost looking happy!

And the 'clamping device' to stop the flow in the hose.

So much for the commentary earlier in the thread, huh?

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Oh, and another observation: Use a lower radiator hose with a spring in it!

 

post-380-080875800 1293782633_thumb.jpg

 

Like clockwork, this happened above 4500-5000 rpms!

 

post-380-030124600 1293782689_thumb.jpg

 

post-380-011917400 1293782730_thumb.jpg

Jeff was busy, and didn't see my 'DUDE THE HOSE IS FLAT!' gesticulations...

Edited by Tony D
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Forget wallpaper, gimme a roll of toilet paper!

 

Ditch the shitty hose, use sections of aluminium pipe joined by rubber hose, like intercooler plumbing.

 

"A very expensive engine running a very cheap hose"

 

Boys!!!! :shock:

Edited by ozconnection
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And has taught me something about the 'stock' exhaust manifold. Hmmmmm.

 

Wastegate plumbing.....not finished there by the looks of it. Some more R and D?

 

Oil cooler?

 

Where does that line go to? Mechanical oil pressure guage?

Edited by ozconnection
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And has taught me something about the 'stock' exhaust manifold. Hmmmmm.

 

Wastegate plumbing.....not finished there by the looks of it. Some more R and D?

 

Oil cooler?

 

Where does that line go to? Mechanical oil pressure guage?

So many assumptions...

1) The hosese on the dyno are supplied by the DYNO. Those ribbed reinforced hoses you see? Those were brought TO THE DYNO by Jeff and I. They were confiscated by the dyno owner in lieu of some dyno time he liked them so much. There WERE 4 sections like that, but one was absconded with hence our using an outlet hose on the inlet. There is no spring in it, and that indeed is what was needed. DO NOT run a lower radiator hose without an anti-collapse spring in it!!!

2) Wastegate plumbing incomplete? LOOK AGAIN! The downpipe is turned at a 45 degree angle relative to where it would be in the car. The wastegate fits just fine to the clearly visible plugged connector on the downpipe when it's in the car.

3) Oil cooler? B) Oil throwoff from the mains and rods was around 100C. Sump temperatures were slightly higher. We were doing cooling systems tests holding the engine at steady state to check for some things. The cooler stayed in the car...for a reason. We learned more without it on the engine that we would have with it on the engine (similar to hooking up the head to the pump inlet and being able to block it off during testing.) BTW, do you need an oil cooler with 220F Oil Sump Temperatures and 170F CHT after running for 5 minutes at 5000rpms steady with XXpsi boost and making a load over 390ft-lbs of torque? B)

4) It looks like a stock block, doesn't it? Try gettting the conditions in #3 above to happen in a bone-stock F54 Block, or N42 for that matter! B)

Edited by Tony D
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The dyno owner, for the record, was NOT happy about me sneaking into the test bay to snap photos with the engine under load...or to take I/R readings on portions of the cooling system we couldn't instrument with RTD's...

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  • 1 month later...

My attempt at reducing the temperature above the 6th, 5th and 4th exhaust ports.

This change has stopped the temperature from slowly creeping up after 10 laps and it now peaks at 190 degrees and stays there.

 

The lines are dash 3 brake lines which are well rated for the heat and pressure and are cheap.

post-955-046086700 1297156075_thumb.jpg

Edited by Ricky
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  • 2 weeks later...

I thought that the focus of this thread was to find a way to prevent overheating at cylinders 5 and 6, to avoid problems like dropped valves (Post #1) and detonation. Ricky is just reporting a lowering of coolant temperature in general. Which seems a little odd actually, since the same volume of water is flowing past the temperature sensor and the same amount of heat should be produced by the engine.

 

It's interesting work, but I don't see the connection between specific hot spots and overall heat removal.

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My attempt at reducing the temperature above the 6th, 5th and 4th exhaust ports.

This change has stopped the temperature from slowly creeping up after 10 laps and it now peaks at 190 degrees and stays there.

 

The lines are dash 3 brake lines which are well rated for the heat and pressure and are cheap.

 

I notice the 3 lines from 4,5,&6 return into the coolant flow after the thermostat housing.

Are you using a thermostat or restrictor?

Where is the temp sensor located?

 

If you are taking the temp reading at the thermostat housing, that might explain the temp drop: hot coolant from 4,5&6 is by-passing the sensor.

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I see the point, The 4,5,6 coolant is constantly bypassing the sensor. But if the engine was overheating then it will still overheat.

 

...UNLESS....

 

The overall efficiency of the system has improved due to reduced steam pockets and surface effects. This was Tony's point all along.

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I see the point, The 4,5,6 coolant is constantly bypassing the sensor. But if the engine was overheating then it will still overheat.

 

...UNLESS....

 

The overall efficiency of the system has improved due to reduced steam pockets and surface effects. This was Tony's point all along.

 

I hadn’t considered the fact that I am bypassing the sensor in the lower thermostat housing, there is a thermostat in the housing.

The engine is running noticeably cooler, I will relocate the hoses into a manifold and run them into the lower thermostat housing and see what the temperature is.

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