zxtman Posted February 24, 2011 Share Posted February 24, 2011 But if the engine was overheating then it will still overheat. Overheating? There is no mention of overheating in Ricky's post. Ricky, it would help to know what temperature you were experiencing after the 10 laps before the by-pass, ...190 degrees is awfully cool for 10 laps of racing. Link to comment Share on other sites More sharing options...
Ricky Posted February 24, 2011 Share Posted February 24, 2011 Overheating? There is no mention of overheating in Ricky's post. Ricky, it would help to know what temperature you were experiencing after the 10 laps before the by-pass, ...190 degrees is awfully cool for 10 laps of racing. The engine would peak at around 215 degrees and the performance would drop off, since adding the by-pass lines and fitting a header tank on the suction side it peaks at 195 when racing. The interesting thing is that after a race if I get held up returning to the pits the temperature will creep up to 220 before it slowly drops back to 180. I have resorted to shutting it down and allowing the fan to cool the water in the radiator then starting it for a minute to pull the cooler water thru. It never boils or loses water other than a little thats blown into the overflow bottle which is drawn back as it cools. I added the by-pass lines after we had some issues with the engine losing compression on those cylinders which was caused by the exhaust valve seats losing their seal. We used a vacuum gauge to test the valve seat to confirm this. At present the engine is producing 330hp so it should be making some heat. Link to comment Share on other sites More sharing options...
Tony D Posted February 25, 2011 Share Posted February 25, 2011 ...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 get giddy when someone actually reads the posts and gets the root benefit out of it. The temperature you read at the THERMOSTAT is considerably LOWER than what is present at the back of the engine. Spot boiling at the back of the engine affects the WHOLE engine and can lead to 'overheating'... One thing to note is that on Jeff's engine we have done CONSIDERABLY MORE than what you can see externally to get it to the point that 170 at the thermostat housing is the same as 170 at the 4/5/6 CHT position. If you have not done our 'internal mods' likely you will have higher temperatures at the CHT reading point (KTM mentioned this in the post earlier.) You may not notice it during regular driving or even 10 laps (KTM says the mods to the head reduced the temperature, but this wasn't held at 450HP for 5 minutes straight, either...) There are other things to do to the engine to improve coolant flow through the block and head that reward you with consistent temperatures, which happen to be lower. I would say with the modifications Jeff and I have done I could now run a 190 degree thermostat without reservation for added thermal benefits... But without these modifications, unless you are running a stratospheric pressure radiator cap to suppress boiling at the back of the head, running a 190 thermostat is asking for problems with heat... Link to comment Share on other sites More sharing options...
Tony D Posted February 25, 2011 Share Posted February 25, 2011 I also call to note that Nissan started different cooling systems on 'high specific output' engines in the L line consistent with 300HP for racing. This is right where Ricky is, and where Zya got his Bob Sharp parts (which block the internal water bypass to the pump suction, and put vent lines into the system...) Ricky next time the head if off, plug the water bypass on the inside of the block---tap the hole and put a flushseal plug in there. You will see added benefit, and if you have a bypassed thermostat with those hoses, you have plenty of flow capacity to prevent pump cavitation during warmup... Link to comment Share on other sites More sharing options...
NewZed Posted February 25, 2011 Share Posted February 25, 2011 I've read the whole thread and it has drifted some from the original Post #1 (not surprising after 22 pages) but Ricky's post has kind of brought it back on topic, to specific problems at the back cylinders. Ricky stated that they "added the by-pass lines after we had some issues with the engine losing compression on those cylinders which was caused by the exhaust valve seats losing their seal. We used a vacuum gauge to test the valve seat to confirm this." He then reports a stable 190 degrees after ten laps as the result, as opposed to creeping up over ten laps. The question of compression loss and loose valve seals due to localized heating is still unanswered. If this mod has fixed that, then the engine should produce more power over the course of the race (no more compression loss), with no loose valve seats at the end. That would make the result of the modification more clear. I've read the whole thread before and I recall waiting for the definitive results to solving the dropped valve seats, or detonation at 5 and 6 problems, but never really saw it. The closest I recall was a report of producing equal, sharp, "sudden onset" detonation across all cylinders. Anyway, thanks to everyone who does this kind of work and shares it. It's fascinating stuff and I wish I had the resources myself to add more to the discussion. Link to comment Share on other sites More sharing options...
rossman Posted February 26, 2011 Share Posted February 26, 2011 Ricky next time the head if off, plug the water bypass on the inside of the block---tap the hole and put a flushseal plug in there. You will see added benefit, and if you have a bypassed thermostat with those hoses, you have plenty of flow capacity to prevent pump cavitation during warmup... Tony - Are you referring to this hole? Tapped and plugged from the deck side? Link to comment Share on other sites More sharing options...
Tony D Posted February 27, 2011 Share Posted February 27, 2011 (edited) Rossman: "yes" If there is a single small external bypass for pre thermostat opening curculation within the block, that passage can be blocked. Most of the guys here are running a turbocharger which has water cooling---a 10mm line which is more than large enough. The previous arrangement was two 8mm's usually... NewZed: "The closest I recall was a report of producing equal, sharp, "sudden onset" detonation across all cylinders." That would be opposed to the consistent detonation across the hottest rear cylinders previously. Or the runaway temperatures at the rear of the engine, as opposed to a consistent temperature at hte Thermostat Housing compared to the CHT monitoring point. Stock the CHT reads 20F or so higher...and that's 'indicated'---you can't go by Thermostat outlet temperatures, that was one of the first things mentioned in the thread. The monitor point for tne engiine water temperature should be CHT, and when you concentrate on decreasing CHT, you result in even temperatures across the whole engine, without the disparity present in the stock engine. Throughout the thread it was mentioned that it wasn't audible detonation that killed you, it was the stuff you didn't hear. By getting a consistent temperature, the tendency to detonate in 4/5/6 first (inaudibly) is greatly reduced. Some may see it as you characterize it above if they push it beyond the point where mixture/combustion chamber design/octane will support smooth combustion. It was happening there before but only in the hottest cylinders at the back. Comprende? Edited February 27, 2011 by Tony D Link to comment Share on other sites More sharing options...
NewZed Posted February 28, 2011 Share Posted February 28, 2011 Si. Maybe there have been more measured results than have been posted in the thread. I just haven't seen many focused results, like actual temperature measurements at the back cylinders, or running more races before the back cylinder exhaust valve seats loosen up, or more boost possible since the modification, or similar. It seems like many people are doing this but it's not clear if they're really getting any benefit. I'm just trying to draw out some more before and after anecdotes about this proposed improvement. Something measurable. Maybe some of the other people who have done this will post their results. Link to comment Share on other sites More sharing options...
Tony D Posted March 1, 2011 Share Posted March 1, 2011 Had a very long response, keyboard dumped it, I'm not doing it again. The modifications work and are documented on a Superflow 901 Dyno. The engine runs a 450HP actual load at 5500+ rpms for 5 minutes straight with stable oil and water temperatures. No difference between the front and back of the engine at coolant temp of 170F... Try that with a stock engine, and then dispute there is any lack of benefit. I PURPOSELY did not give readings along the way and instead concentrated on beginning and ending results. Read my last posts again to read the difference between a stock engine with a paltry 25hp load on it and the temperature disparity with just that load on it. Then realize we had 18 TIMES that load on it and maintained 170F at the CHT and Thermostat with absolutely NO disparity in temperatures. If this is not effective, what is? Like I said, I had a very detailed response and I'm pretty P.O. right now that it was dumped. I'm not going into it further, and I'm not writing a white paper on it. Long and short of it, VW and Corvair heads will melt near 600F CHT and they won't drop their seats, if you are dropping yours, discuss the proper assembly techniques with your head builder, they don't have enough interference! It's an assembly issue more than a head heat issue. This modification if meant to keep heat moving out of the engine to prevent runaway temperatures and a detonation or thermal lock of the engine. Your valve seat issue is with your assembler and technique, likely it will still happen with this modification, but take longer as it's running cooler back there... Link to comment Share on other sites More sharing options...
jeffp Posted March 8, 2011 Share Posted March 8, 2011 The bottom line of all the testing I did in the car, on the engine stand points to one thing, the engine getting hot, to hot to run hard. I have had heating problrms that I could see between 3&4 and I am sure 5&6 were having problems as well. Now that there are people pushing over 350hp they are starting to see what I have been dealing with for a number of years. The head cooling on the L series standard engine SUCKS! The second part is that the block sucks also! I don't know how much time and effory any of you have put in on this issue, but I can tell you I ended up spending close to 3ooo.oo with machine work, and dyno time to get the engine so that it could be tested with its new changes. I have run the car, and now I see that when the engine starts getting hot, and I have the fan set to about 175-180 degrees, that as the fan turnes on, the engine starts to cool down. That is one improvement I was very happy to see, when the fan is on the engine cools, and I can watch the temp gauge go down. Running down the road, I have not seen any problems, so far, but I have not pushed the engine to hard thus far. I was having problems with the alternator belt. I am not done with testing, i want to run the car in its, new home, container so that the ambient temp rises to about 80-90 degrees F and observe the temp of the engine. that will be my best test, with the A/C on. I could make the car overheat in my garage in santa ana in the summer time running the car in the garage with the A/C on, so if that is not happening any longer, then as far as I am concrened the problem is a non issue now for the most part. One thing I do know for sure, if you are running 500hp or higher, you need to do something about the cooling of the engine, no question about it! The last thing to deal with is the system pressure, and if you increase the pressure as Tony said you hinder the bubbles from starting in the exhaust port of the head. Take a look at the sectioned head Jeff did, note the rust build up in specific areas of the head water passages. You will see that there is very little water flow in those areas, and that is the big problem. Link to comment Share on other sites More sharing options...
zxtman Posted April 6, 2011 Share Posted April 6, 2011 Ok so with all of this discussion, I think I am going to jump off this cliff and have the cylinderhead done from #2-#6. I don't think #1 is really an issue as it is right at that large hole for the thermostat housing. I have completed #5 & 6, and was intending on doing # 3 but between 3 & 4 is difficult to do. I have already invested about 300 in what I have done, but the union T I used (swedgelock) is to big to get between 3 & 4 so a redesign is in order. I will get the 1/4 NPT fittings, do the intake clearancing for 3-4 use the A/N fittings and run the tubes to a common tube 1/2" but instead of using fittings have each tibe TIG welded to the common return pipe. I use a local welder here Master Craft Welding to do the work. This guys TIG welding is the best I have ever seen, very percise and very clean. I have him do the work I want to look good and be strong. I have already bought all of the -6 45 1/4" NPT fittings. Getting around the head stud between 3-4 is going to be the tough one, but I think it is doable. And just to make sure where it needs to go, I have a good door stopper P90 head I will section to make sure of the fitting locations. Why is it that every time I get involved in this stuff it starts costing me lots of money LOL, but its only money right? Anyway this is just part of the crap I am working on right now, and since I just dropped close to 4 grand on components for a race head what the hell! Were you successful at installing fittings at 3 & 4?? Link to comment Share on other sites More sharing options...
Tony D Posted April 20, 2011 Share Posted April 20, 2011 Oh, this is where the thread went... Yes, it was a successful install. Jeff and I (as well as Frank 280ZX and Andy Flagg) had a little get-together at the MSA event to discuss some more things on this. Really, with the size hoses everbody is using it's amazing the results we are achieving. Reviewing archival photos recently with a caliper in-hand, the stuff used in the past was much larger! So for you 1100HP L-Gata Endurance Racers.... use bigger lines than discussed in this thread! Link to comment Share on other sites More sharing options...
Oddmanout84 Posted April 26, 2011 Share Posted April 26, 2011 (edited) I'd just like to add that it's really annoying that I can no longer view the photos in this thread due to the latest restructuring. Edited April 26, 2011 by Oddmanout84 Link to comment Share on other sites More sharing options...
Tony D Posted April 27, 2011 Share Posted April 27, 2011 that's an interesting development... Link to comment Share on other sites More sharing options...
zxtman Posted April 30, 2011 Share Posted April 30, 2011 Yes, it was a successful install. Before I start making swiss cheese out of my P90, I'd like to know where the water passages are above 3&4, and whether one fitting is needed above each, or one fitting for both (centered between 3&4)??? Reviewing archival photos recently with a caliper in-hand, the stuff used in the past was much larger! I've noticed this as well: looks like -8 minimum, maybe even -10 was used on the Electromotive car. Originally, my plan was to use 1/4 NPT to -6 fittings, but I am considering going with 3/8 NPT to -8. I just need to resolve the issue with 3&4. Thanks.. Link to comment Share on other sites More sharing options...
Oddmanout84 Posted May 1, 2011 Share Posted May 1, 2011 I'm using -8 for mine, and trying to send #6-to-#5-to-thermostat housing via a T-fitting. I'd like to do #3 and #4 as well, but I have to figure out the situation with the previous two before I try to tackle that. The size of the -8 fittings and hose makes it really difficult to cram everything in there together. The hose end fittings from #6 to #5 are almost touching each other, with no hose installed! Link to comment Share on other sites More sharing options...
Tony D Posted May 1, 2011 Share Posted May 1, 2011 You need to send JeffP a PM or e-mail. I believe he did a single tap abouve 3/4 because of the proximity of the exhaust. He can tell you in thousandths of an inch where he tapped referenced off some existing hole or stud or whatever. Thousandths of an inch... Link to comment Share on other sites More sharing options...
Administrators RTz Posted May 1, 2011 Administrators Share Posted May 1, 2011 Are the pictures coming in for you guy's now? Link to comment Share on other sites More sharing options...
rossman Posted May 1, 2011 Share Posted May 1, 2011 Are the pictures coming in for you guy's now? I see them. Link to comment Share on other sites More sharing options...
Tony D Posted May 1, 2011 Share Posted May 1, 2011 Works now for me as well, thanks. Link to comment Share on other sites More sharing options...
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