rsicard Posted August 28, 2009 Share Posted August 28, 2009 Tony: Your point is well taken. After reading the entire thread there seems to be a reluctance to recognize the benefits of cooling the cylinder head directly with cooler fluid. Link to comment Share on other sites More sharing options...
Zmanco Posted August 28, 2009 Share Posted August 28, 2009 I'm in the middle of building up my first turbo motor and am planning on adding the nipples to the back cylinders. My question is if I should do just 5 and 6, or 4, 5, and 6? With the head off it's not big deal to do 4 as well, but I figure that will add more flow into the return line (I plan to connect to an unused nipple on the thermostat housing) and could reduce flow to 5 and 6 which seem to need it most. My goal is to have a reliable 275 - 300 whp engine that I can run on the track (road course with 20 minute sessions) hence cooling is going to be key for longevity. Link to comment Share on other sites More sharing options...
DuoWing Posted August 29, 2009 Share Posted August 29, 2009 I wish I could do what someone wanted, but here's my take on this whole thread. Someone let me know if I got it right. Basically the way Nissan designed the cooling system in the L-Series motors was a design flaw. Along with small casting flaws, etc act to work against the cooling system. Another part of our issues is with people's cooling systems simply not being up to snuff' for years. Anyway it seems like Nissan never addressed the cooling issue in the cars as the normal Z car sold was never figured to be used heavily or used at all as far as racing or heavy load goes. Anyway it seems the best possible solution for our cars is to use a higher pressure pump, reverse flow the entire coolant system with slightly better routing? Although overall the best solution(time/money/ease) for us is to use the suggestion that was repeatedly mentioned throughout this thread. Drill and Tap 1/4" NPT holes above cylinders #4, #5, and #6 then using fittings and lines route them into either the lower Thermostat housing, the upper radiator hose, or even directly into the radiator(however you see fit). As this basically will allow for better overall flow, smoother flow, and in the event of cavitation which is bound to happen a place to allow the steam pockets that form a place to escape quickly rather than sit and manifest and begin to cause damage. Now as Zmanco above is saying about having those tapped could cause less flow to those cylinders, but it seems like having it tapped up in the head really isn't diverting the flow much as the coolant is still making it's way from the bottom to the top. It's just providing more routing for the coolant and to keep it flowing quicker? Oh and with these solutions use the correct antifreeze mix with water wetter, or go a step further and use distilled water with the water wetter as it is another helpful tool in keeping temps down. I can't remember what the other type of coolant people were switching to was called or what was special about it. I'd have to go back and read more towards the beginning. So guys did I get it right? Did my reading comprehension work? I'm definitely planning on doing the 4-6 bypass to my spare P90 head and have it fully rebuilt. I'm probably going to have to end up pulling my existing head as is... Link to comment Share on other sites More sharing options...
Zmanco Posted August 30, 2009 Share Posted August 30, 2009 I read the thread all the way from the beginning (again) and decided to only do 5 and 6. I'm guessing that the benefit of including 4 would be offset by reducing the flow from 5 and 6. We have a track day on Sept 12 that I'm hoping to attend and that will be a good test of this mod. Link to comment Share on other sites More sharing options...
Tony D Posted August 30, 2009 Share Posted August 30, 2009 "Someone let me know if I got it right. Basically the way Nissan designed the cooling system in the L-Series motors was a design flaw." This is a serious overstatement of the situation. The decision was made based on intended usage of the engine. The LY head and FIA heads were designed with high specific output usage. This engine head is NOT in a high specific output application. Characterizing it as a 'design flaw' seriously overstated a marketing decision, as well as a basic engineering decision. The design of the head and it's propensity to detonate is more important than a slighly lower flow of coolant through the last coulpe of cylinders. And that was pretty much state of the art for the day. Remember you are working with EMISSIONS DESIGNED compopnenetry as well. This is US market crap. Don't blame Nissan for compliance with governmental mandates. We are talking about an engine which is easily taking 2X stock horsepower without ANY issues whatsoever. I would consider that pretty darned GOOD designing. Especially when you don't really run into an issue till almost 3X the stock horsepower level! AND AGAIN: We are adding cooling to combat hot runing of a BAD COMBUSTION CHAMBER DESIGN CHOSEN. Spend $2400+ for a reshaped combustion chamber and anotehr $800 for custom pistons to give a fast-burn and I think you will be amaze how much HP you can make on current crap pump gas without needing the extra coolant flow. "Along with small casting flaws, etc act to work against the cooling system." Casting flash. This is unavoidable with the casting methods of the day. Everydoby had it, and if people don't properly prepare their components this can have an effect. "Another part of our issues is with people's cooling systems simply not being up to snuff' for years. Anyway it seems like Nissan never addressed the cooling issue in the cars as the normal Z car sold was never figured to be used heavily or used at all as far as racing or heavy load goes." Not using the vehicle as intended is not a Nissan Issue. It's the builder's issue. Most people don't properly engineer their vehicles for the application, then blame the OEM afterwards. This appears to be what is being said here. Is it? Then I would say 'no'. Nissan had a cooling system outside the US A that worked. But our cars were decontented and lacked things like splash pans, spoilers for air, etc... Again, governmental or marketing decisions that were uncontrollable by the engineering department. "Anyway it seems the best possible solution for our cars is to use a higher pressure pump, reverse flow the entire coolant system with slightly better routing?" If you are looking to make 700+ hp, probably, yes. For Less than that, common preparation and attention to the combustion chamber design is likely to play FAR more dividends with combatting detonation. But at a starting cost of $3000+, nobody wants to do that straight out the gate. So you are left band-aiding everything else to make a misapplied component do something it was never intended to do in the first place. Making a silk purse out of a sows ear, as it were. "Although overall the best solution(time/money/ease) for us is to use the suggestion that was repeatedly mentioned throughout this thread. Drill and Tap 1/4" NPT holes above cylinders #4, #5, and #6 then using fittings and lines route them into either the lower Thermostat housing, the upper radiator hose, or even directly into the radiator(however you see fit)." "BEST"? There is no "BEST"! The most practical may be to do that, but really the 'best' solution is to start with a fast-burn head to prevent an issue with 'cooling' under high specific output. If you have a detonation resistant combustion chamber, then the cooling may not even surface as an 'issue'... "As this basically will allow for better overall flow, smoother flow, and in the event of cavitation which is bound to happen a place to allow the steam pockets that form a place to escape quickly rather than sit and manifest and begin to cause damage." More that there is no flow inhibition by stronger currents closer to the front of the engine causing flow stagnation. Higher pressure caps will help with the cavitation and thermal layer boiling. The big thing is you have SIMILAR flows through ALL cylinder heads. Equal flow. Same as CC'ing a head, or porting the intake to flow the same. "Now as Zmanco above is saying about having those tapped could cause less flow to those cylinders, but it seems like having it tapped up in the head really isn't diverting the flow much as the coolant is still making it's way from the bottom to the top. It's just providing more routing for the coolant and to keep it flowing quicker?" It, as said just above, equalizes flow through the cylinders so they all flow similarly in terms of coolant. This is what you want, not good cooling up front, poorer cooling out back. "Oh and with these solutions use the correct antifreeze mix with water wetter, or go a step further and use distilled water with the water wetter as it is another helpful tool in keeping temps down. I can't remember what the other type of coolant people were switching to was called or what was special about it. I'd have to go back and read more towards the beginning." Evans NPG, it's nucleate boiling characterisic is different. It has surfectant properties, and can be run much hotter. In all ANYTHING other that pure water has a POORER heat transfer ability. Water being 1, Evans being .8, 50/50 Glycol being .7, and increasing as the glycol concentration goes down. Remember I said anything above 10% glycol will require refiguring heat transfer rates. "So guys did I get it right? Did my reading comprehension work? I'm definitely planning on doing the 4-6 bypass to my spare P90 head and have it fully rebuilt. I'm probably going to have to end up pulling my existing head as is..." You be the judge by the commentary. Link to comment Share on other sites More sharing options...
Administrators BRAAP Posted August 30, 2009 Administrators Share Posted August 30, 2009 Good stuff Tony. One question though, as it applies to the L-6 for guys wanting to build a little more power, (N/A or boosted, example is N/A) Lately I've noticed quite a bit of interest in guys wanting intently focused on increasing compression ratio only, even just a little, some for stock applications, as means to increase performance, particularly the N/A crowd. Guys wanting to go from the 8.3:1 to 9.5:1, even 10:1. I have been steering them away from focusing so intently on the C/R increase as that little bit of a power bump from just the mild C/R bump alone, (if it didn't rattle at full ignition advance), is not going to come cheaply. I've been trying to steer them towards other avenues, leaving h low comp ratio to avoid the rattle demons. Linking this thread as an approach to allow a real bump in compression that would be worth while jumping up to, ratios that the L-6 should be able to run with pump gas with full ignition timing without rattling. By rights, an aluminum head 2 valve engine on premium pump gas should be able to full ignition timing with 10.5:1, even 11:1 compression ratio. I have seen Iron head GM small BLock run 9.8:1 on premium pump gas, no rattle. Aluminum head L-6 generally will rattle at that level proving itself to be more sensitive than most to audible rattle at such comp ratios, (I am referring to the US spec Z car heads, not the MN47 or non us offerings). … Spend $2400+ for a reshaped combustion chamber and anotehr $800 for custom pistons to give a fast-burn and I think you will be amaze how much HP you can make on current crap pump gas without needing the extra coolant flow. … You mention fast burn chamber designs with matching pistons, leaving the stock cooling paths as is. I agree that the fast burn design helps, but with the money and time spent on what it would take to achieve a fast burn chamber form the available US Z car heads and matching pistons, with the L-6’s sensitivity to detonate so easily, wouldn’t the engine still be riding that fine edge of the envelope, possibly crossing that line say on hotter than normal days, heavy stop and go traffic, more than usual bugs/dust on the radiator fins, etc? Depending on the budget, parts availability, etc, it seems that in some instances, maybe even more often than not, that a simple rudimentary version of the external bypass, say just the #5 and #6 bypass to the T-stat housing would be a more cost/time effective approach for the typical US L-6 build vs the custom head, pistons etc? Along with that, wouldn't that also allow added buffer room for those really hot days in stop and go traffic etc? Your thoughts? Link to comment Share on other sites More sharing options...
Tony D Posted August 30, 2009 Share Posted August 30, 2009 It might aid in the cylinder to cylinder consistency, as a general matter of building any higher specific output engine, it only makes sense. But it's not the solution---it helps make everything in a bad combination of parts work a little longer, but the solution is a mechanical redesign, rather than an aftermarket 'band-aid' to cylinders in the back detonating. Note KTM's later blowup where all the cylinders simultaneously seemed to go 'boom' at one time. The consistency ended up having it all happen consistently....in every cylinder instead of the two running marginally hotter. Goes back to cylinder combustion chamber design. As I said, the FIA and LY heads both have seriously altered coolant flow from the head...really flow equalization than anything else. They have a tendency to catastrophically go 'boom' in all six when something goes bad. But they are running high compression, and running to 9K rpms+! There are some other things that can be done, but I can't get into them now in public due to some agreements in place. You mention MN47...that is a detonation resistant chamber simply due to the size promoting the faster burn. People seem to be running higher compression with that head on an L28, than the same head will accept on the L24 it was designed to be on... When you compare the slight difference in piston diameter, and how it's a problem with one engine and not the other, you start asking questions, right? There are some secrets out there still, one being the highest horsepower L's out there in the USA used NON-USA HEADS as a starting point for their builds. Similarly to the results that an L24 head on an L28 worked. Don Potter preferred L26 E88 Heads, for instance. Nissan Competition supplied some non-us heads for competitors back in the 80's which have even smaller chambers than the MN47! But it's a 'blank slate' then, and you can shape to promote the best chamber possible without welding and decking the head. I digress... Link to comment Share on other sites More sharing options...
DuoWing Posted August 31, 2009 Share Posted August 31, 2009 Well from the way it sounds at least doing the 4-6 cylinder bypass would definitely be an improvement to what we have. I see what you're saying by redesign the head and combustion chamber, but mainly for the money, time and, effort it seems like the bypass is the most feasible design. At least like you said with KTM's motor eventually going boom consistently sounds like an improvement over stock whether we call it a band-aid fix or not. Anyway like Zmanco was asking, if you were to tap and bypass 4-6 would that cause any kind of flow discrepancy vs. doing the cylinder 5-6 bypass or would you still be alright as far as cooling goes to those cylinders? Basically I'm planning to do 4-6 to my spare P90, so more or less is there any reason to not do the cylinders 4-6 bypass? Link to comment Share on other sites More sharing options...
Zmanco Posted August 31, 2009 Share Posted August 31, 2009 I added fittings to 5 and 6 this weekend. I decided not to do 4 because it's not clear from this discussion if the trade off of better cooling on 4 has any negative effect on reducing cooling on 5 and 6 which seem to need it more. Also, I noticed that the intake manifold has webbing where 4 would need to be drilled. Did others just remove the little plate and drill a large enough hole to fit the nipple, or is there some other approach that I'm missing? This webbing exists on both the ZX and turbo intakes, not sure on the earlier ones without EGR. Link to comment Share on other sites More sharing options...
FlatBlack Posted August 31, 2009 Share Posted August 31, 2009 I added fittings to 5 and 6 this weekend. I decided not to do 4 because it's not clear from this discussion if the trade off of better cooling on 4 has any negative effect on reducing cooling on 5 and 6 which seem to need it more. Also, I noticed that the intake manifold has webbing where 4 would need to be drilled. Did others just remove the little plate and drill a large enough hole to fit the nipple, or is there some other approach that I'm missing? This webbing exists on both the ZX and turbo intakes, not sure on the earlier ones without EGR. Would you upload pictures of your setup? Link to comment Share on other sites More sharing options...
DuoWing Posted August 31, 2009 Share Posted August 31, 2009 The earlier intakes like my non-egr N42 intake doesn't have the webbing which would probably make it easier then for port 4. Link to comment Share on other sites More sharing options...
Tony D Posted August 31, 2009 Share Posted August 31, 2009 internet ate my answer...dammit Link to comment Share on other sites More sharing options...
Zmanco Posted September 1, 2009 Share Posted September 1, 2009 Would you upload pictures of your setup? Here's my setup without hoses. Sorry about the camera phone pictures as I saw your reply just before I had to leave early this am and won't be back until the weekend. The nipples on 5 and 6 will be connected to a T that runs to the thermostat housing. Link to comment Share on other sites More sharing options...
FlatBlack Posted September 1, 2009 Share Posted September 1, 2009 Thanks I will definitely be doing this to the L28ET, and maybe the P79 if I feel lucky. Did you do it with the head off or still on the block? With the head off it's not big deal to do 4 as well *edit* I found the answer ^ Is there any way that you could empirically measure the results? It would fend off the naysayers if we could prove it works. *edit* Should have re-read the whole thing before I posted ^ Link to comment Share on other sites More sharing options...
Zmanco Posted September 1, 2009 Share Posted September 1, 2009 Did you do it with the head off or still on the block? Is there any way that you could empirically measure the results? It would fend off the naysayers if we could prove it works. I had the head off - I wouldn't recommend doing it on - I don't see how to avoid getting AL chips in the cooling system. I'm in the process of converting to turbo so don't have a non-5/6 mod baseline with this engine. However, obviously I am going to be putting more thermal load on the engine when at the track and hope that I won't see the temps go up. If everything goes well, I will have it out on the track in 2 weeks and learn more then. Link to comment Share on other sites More sharing options...
Tony D Posted September 1, 2009 Share Posted September 1, 2009 1) aluminum chip issue is discussed in the thread. (??? Concern of Aluminum Chips in Coolant... Anybody ever hear of alumaseal???) 2) empirically measured results are in the thread. Link to comment Share on other sites More sharing options...
FlatBlack Posted September 1, 2009 Share Posted September 1, 2009 1) aluminum chip issue is discussed in the thread. (??? Concern of Aluminum Chips in Coolant... Anybody ever hear of alumaseal???)2) empirically measured results are in the thread. Sorry Tony Link to comment Share on other sites More sharing options...
DuoWing Posted September 1, 2009 Share Posted September 1, 2009 Zmanco, did you use 1/4" NPT threads? It seems like that's what everyone is using and probably what I'll go with on my head. Link to comment Share on other sites More sharing options...
Zmanco Posted September 1, 2009 Share Posted September 1, 2009 Yes, 1/4" NPT. Easier to work with than 3/8" NPT. Link to comment Share on other sites More sharing options...
WizardBlack Posted September 21, 2009 Share Posted September 21, 2009 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 Link to comment Share on other sites More sharing options...
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