Engine temperature tests and results

[ozconnection]

I just thought I briefly say that this is a fascinating thread, and a very relevant discussion - along with the previously mentioned thread on the coolant flow improvement.

 

If nothing else, I will seriously consider; a) an LD pump, , 5&6 supplementary flow mods, and c) a 1.5-bar cap for my F54/P90 engine currently under construction.

 

Again, I for one appreciate the R&D going into this matter.

 

 

Ben, it's been mentioned by several people, including yourself now, about using a high pressure radiator cap.

 

Firstly, where do you get them from?

 

Secondly, I can't see the point IF you're running a thermostat or a restrictor in the water thermostat housing. I'm thinking that if one were to NOT run either of these, the WHOLE cooling system will run up to 1.5 bar (21 or 22 psi, I think?) Why do this? Just keep the block pressurised, where it's needed, and leave the rest to a more standard pressure of up to 13-14 psi max. Can we save the hoses and radiator from those enormous and perhaps dangerous pressures? People are doing it but do they really understand why they're doing it?

 

Hey, doesn't this just confirm something? Running a higher than stock cap IS an ATTEMPT to increase block coolant pressure???

[ktm]

Ben, it's been mentioned by several people, including yourself now, about using a high pressure radiator cap.

 

I am using the 20 psi Motorad cap that came with my Arizona Z Car aluminum radiator. I can buy 16 psi caps at my local autoparts store any time.

 

Secondly, I can't see the point IF you're running a thermostat or a restrictor in the water thermostat housing. I'm thinking that if one were to NOT run either of these, the WHOLE cooling system will run up to 1.5 bar (21 or 22 psi, I think?) Why do this? Just keep the block pressurised, where it's needed, and leave the rest to a more standard pressure of up to 13-14 psi max. Can we save the hoses and radiator from those enormous and perhaps dangerous pressures? People are doing it but do they really understand why they're doing it?

 

Yes, yes we do understand why we are doing it. Do you understand the Ideal Gas Law and the affects of pressure on water's (coolant) boiling point? Increasing the pressure increases the boiling point of the liquid.

 

Just because I have a 20 psi cap does not mean that my system reaches 20 psi. Read Tony D's posts carefully and let it sink in. If your cooling system is able to reach thermal equilibrium at, say, 10 psi system pressure, then your pressure will not exceed 10 psi. Your radiator cap will not vent the excess pressure because there is no excess pressure.

 

Your 13 psi cap allows the system to reach 13 psi thereby increasing the boiling point of your coolant.

 

The higher the rating of the cap, the higher the thermal equilibrium threshold.

 

Read this: http://auto.howstuffworks.com/cooling-system7.htm

 

Hey, doesn't this just confirm something? Running a higher than stock cap IS an ATTEMPT to increase block coolant pressure???

 

No. It's to raise the boiling point of the coolant.

[Zmanco]

ozconnection asks a question I was wondering about as well, but let me ask it a little differently: I follow how a higher pressure cap will allow the system to reach a higher temperature at thermal equilibrium without venting. However, I think it's also being suggested that a higher pressure cap will help reduce localized boiling that creates steam pockets in the head. If that occurs with a 13 psi cap that is not venting/overflowing, I don't understand how switching to a higher pressure cap would change it. Am I missing something?

[ozconnection]

I am using the 20 psi Motorad cap that came with my Arizona Z Car aluminum radiator. I can buy 16 psi caps at my local autoparts store any time.

 

 

 

Yes, yes we do understand why we are doing it. Do you understand the Ideal Gas Law and the affects of pressure on water's (coolant) boiling point? Increasing the pressure increases the boiling point of the liquid.

 

Just because I have a 20 psi cap does not mean that my system reaches 20 psi. Read Tony D's posts carefully and let it sink in. If your cooling system is able to reach thermal equilibrium at, say, 10 psi system pressure, then your pressure will not exceed 10 psi. Your radiator cap will not vent the excess pressure because there is no excess pressure.

 

Your 13 psi cap allows the system to reach 13 psi thereby increasing the boiling point of your coolant.

 

The higher the rating of the cap, the higher the thermal equilibrium threshold.

 

Read this: http://auto.howstuffworks.com/cooling-system7.htm

 

 

 

No. It's to raise the boiling point of the coolant.

 

We were asked years ago in a Science class "Can someone tell me what is the boiling point of water please?"

Simple, heaps of kids put up their hands and when asked, all of them said "100 degrees celcius , sir".

Of course, he went on to quantify our responses with " at what pressure?" Now we all looked a bit puzzled and didn't really understand the relationship he wanted us to understand at the time. However, it was a good lesson, and one that I've taught my children about!! So yes, yes KTM, I do 'get the gist'

 

By your own statements KTM, you said you haven't solved all of your cooling problems. Have you investigated your block pressure? What size restrictor plate do you use? Do you use a different sized water pump pulley or do you have an alternate sized ie aftermarket harmonic balancer with a differently sized pulley? Is you car pure street or track or somewhere in between? This goes back to what you've said that different situations require different solutions. I hear you loud and clear....mate can you hear me?

 

I re-read Tony's post several times and I think I understand what he's trying to say. Thank you for referring me back to it.

[Ben]

ozconnection asks a question I was wondering about as well, but let me ask it a little differently: I follow how a higher pressure cap will allow the system to reach a higher temperature at thermal equilibrium without venting. However, I think it's also being suggested that a higher pressure cap will help reduce localized boiling that creates steam pockets in the head. If that occurs with a 13 psi cap that is not venting/overflowing, I don't understand how switching to a higher pressure cap would change it. Am I missing something?

 

Thermostats aside, a cooling system that has not reached capacity can only cool to a certain temperature differential (excuse my lack of correct terminology, it's been a long time since I did any physics...). As the ambient temperature rises, the capability to maintain the desired coolant temperature decreases. Hence why cars are more prone to overheat on hot days - a substandard cooling system reaches capacity due to the ambient temperature and cannot shed the heat faster than it's being produced.

 

Where I'm going with this is that in the climate my car operates in, the ambient temperature can rise to well over 40C - we had a 45C last summer - and my work car was operating within-spec at 113C coolant temperature (I tried to boil it, really I did!).

 

In these conditions, the engine coolant certainly gets hot enough to cause a 13psi cap to vent and then recover (I have a recovery cap/tank on my 240Z).

When running my Z-car on the dyno at ~95C coolant temperature, the venting was sufficient to overflow the recovery tank, which then means that when the engine cools, there is a significant chance of having a low coolant level, which in turn leaves compressible gas in the system.

 

That gives the system the perfect opportunity to allow steam pockets to form at the worst time, in the worst place...

 

For me, a higher pressure cap has merit in containing the coolant on a hot day, and reducing the likelihood of hot-spots forming around the chambers when the going gets tough.

 

Not that I'm a big fan of doing it, but my work car operates at around 100C on a 20C day - probably to allow for leaner mixtures and the more favourable economy that follows. I get real nervous of the spring-type hose clamps operating at that system temp/pressure. But it's all by-design, and thankfully it's not my problem if something fails!

[Zmanco]

Ben, the situation I'm asking about is where the temperature as reported by a sensor in the thermostat housing (in my case read by Megasquirt) reads around 195 typical (I run with a 192F thermostat) and even under load on the track, the temps are not exceeding around 215F. I never see anything in the overflow tank, and if I pull the hose off the radiator nipple, it's dry.

 

So my question is if the conditions never cause the 13 psi cap to vent, how would putting a higher pressure cap on reduce spot boiling in the head?

[Ben]

I don't think it would. But I defer to the professionals in the field, as I too may be missing something!

[Tony D]

ozconnection asks a question I was wondering about as well, but let me ask it a little differently: I follow how a higher pressure cap will allow the system to reach a higher temperature at thermal equilibrium without venting. However, I think it's also being suggested that a higher pressure cap will help reduce localized boiling that creates steam pockets in the head. If that occurs with a 13 psi cap that is not venting/overflowing, I don't understand how switching to a higher pressure cap would change it. Am I missing something?

 

You need to go to the grapeaperacing site and read the information on cooling there, this will make it crystal clear why spot boiling will cause a runaway thermal situation in an engine. Steam is an insulator, and once the steam blankets the head from spot boiling, it can't transfer heat, and then it all goes to hell.

 

By raising the boiling point through pressure, you decrease the tendency to spot boil. Look who is having problems: people with 160 degree thermostats running 20psi caps! If it's happening there, what do you think is happening with 190 thermostats?

 

Because you have 'steam' it doesn't mean 'boilover'---it can go back into solution as it hits cooler water. You will never know it!

 

I got into a debate with someone here about radiator cap pressures because they contended c ap pressure was the same as block pressure. The only people who say that are people who have never run a water pressure gauge on their engine...it's a foolish contention to make. You have close to 40psi in your block with a 16psi cap and the engine at speed. With a higher pressure cap, the NPSH on the pump is higher, and your output pressure is higher. When you realize this is the conditions below the restrictor plate/thermostat, you can start to see exactly how hot some of the head pockets are getting!

 

Anybody but me ever jig up a thermostat housing with a thermostat in it and start applying pressure to see at what point the thermostat acts as a 'relief valve' and lifts off it's seat? Once you do that, after you have witnessed for youreslf what pressures exist in the block at speed with a conventional 1 bar rad cap, you will realize why restrictor plates are run, and why they run a 30 psi cap+ on racing L's making 1000 hp.

 

Some of the information in the "How To Modify" book was altered to the expected audience, or because of someone's understanding of why things are done the way they are... but may not necessarily be true.

 

I mean, if a thermostat lifts at 50 or 60 psi anyway, why bother with it at all and simply put in a flow restricting orifice which will do the same thing and doesn't have the possibility of failing or having a variable flow rate dependent on engine speed (and consequently block pressure)?

 

As for comments about ambient temperature, you are off the mark somewhat. I have personally recorded a 25C day where the engine was operating in a more severe environment than a 40C day elsewhere on the same continent. What is important is macadam thermal layering. This is the temperature your RADIATOR encounters on any given day. It may be 40 and overcast, no problems. 40 and clear and you overheat. Because the thermal radiation warming the macadam surface of the roadway up to 1M from the surface can be considerably hotter than ambient. I have seen (I regress to Farenheit for my own specific clarity) 85 Ambient but 130 through the radiator in Southern CA climbing hte Baker Grade and had to slow to 65mph to keep the car from surging (and engine temperatures at 195+), and three days later in Iowa was going 110mph at 103F ambient, with a 105 thermal layer on a clear day (engine temperature no more than 170), but with the midwestern aerosols blocking UV radiation on the roadway.

 

Yes, on some of my trips, I has 100ohm Platinum RTD's and J/K thermocouples taped and wired all over my car, and my kid was writing down numbers as I drove (kept the kid busy... on the return trip from Canada, this 8 year old decided to read Beowulf...)

 

On this particular trip, based on previous long trip experience I brought along 8liters of premix to add to the radiator for the 'shutdown puke' that occurs on the cars after you shut them down hot after a long highway run. The previous summer I puked 4L over a 1500 mile round trip. I assumed it would be similar with similar conditions.

 

One variable had changed: Water Wetter.

 

On this longer trip, I had the coolant in the same ratios, the same thermostat (160F) in the same car, with the same radiator, blah blah blah. KTM has seen 'The Blue Turd' and can attest firsthand that not much changes on that car year to year (or decade to decade!) On my trip to Canada I did not loose ONE liter over the course of three weeks driving and close to 18,000 miles. The decreased surface tension caused by the water wetter completely STOPPED the 'pops and crackles' I could hear within the head after shutdown. It stopped pressure rise to the cap venting point. If you run in hot weather, run a 160 thermostat, and water wetter. I've done so in my Fairlady Z with a recovery tank, and though thermal expansion may occur, in many years of driving I've not lost nor had to add anything to that car either. The Turd does not puke after shutdown like it did before WW.

 

Run a 190 thermostat, and sure as hell you will puke! Even with water wetter. If someone wants to do the theermodynamic calculations to justify the adibiatic advantages of running the hotter water temperature and put them out there for everyone to see, be my guest. But this requirement that we run these 190 thermostats (which in Nissan Manuals is called for ONLY in "FRIGID" climates) is purely based on theoretical bunk... there is a marginal aadvantage but in practical terms the headaches you encounter make it not worth the effort. Your oil gets to the required 180F with a 160 thermostat (the coldest recommended by Nissan---for 'tropical' climates, curious how it works like that, huh?) and will run hotter depending on load.

 

"So my question is if the conditions never cause the 13 psi cap to vent, how would putting a higher pressure cap on reduce spot boiling in the head? "

Hopefully above has told you why. To put it more succintly and without the long read: Higher Pressures in the block will RAISE THE BOILING POINT (and this decreases the tendency to boil...right?) The higher pressure cap IS NOT TO PREVENT VENTING it is there to raise the boiling point so it doesn't spot boil, and then insulate everything---read the grapeaperacing page!

 

I digress...time to go to lunch anyway.

[Zmanco]

Tony D, thanks for the further details. I went and read the grape ape racing article - great read! I follow that reasoning and agree with it. Yet I have to try one more time to clarify the question I'm asking because I suspect we're talking apples and oranges right now.

 

My own experience with puking coolant is a bit different than yours. In brief, mine doesn't do it. I'm sure part of it might be that here in Colorado we rarely see days over 100F. And when I come off the track on a hot summer day I open the hood and let it idle for a few minutes until the temps are normal. But the point I'm trying to make is that regardless if I continue to use the stock 13 psi cap, or if I put a higher pressure cap on, since the cap is never opening up (meaning the radiator (not block) pressure isn't exceeding 13 psi) then what advantage would there be to putting a higher pressure cap on it?

 

Again, I'm not challenging that the pressures in the head are higher and this helps prevent nucleate boiling - I understand all that. I'm just challenging the advice I've seen a few times here that putting a higher pressure cap on the radiator would help reduce detonation. I just don't see how that can be if the system has enough capacity (as mine does) to operate without venting with the stock 13 psi cap?

[ktm]

We were asked years ago in a Science class "Can someone tell me what is the boiling point of water please?"

Simple, heaps of kids put up their hands and when asked, all of them said "100 degrees celcius , sir".

Of course, he went on to quantify our responses with " at what pressure?" Now we all looked a bit puzzled and didn't really understand the relationship he wanted us to understand at the time. However, it was a good lesson, and one that I've taught my children about!! So yes, yes KTM, I do 'get the gist'

 

I did not mean to come across as condescending in my post. However, you asked a question that made it seem like you did not understand why higher pressure caps are used.

 

By your own statements KTM, you said you haven't solved all of your cooling problems. Have you investigated your block pressure? What size restrictor plate do you use? Do you use a different sized water pump pulley or do you have an alternate sized ie aftermarket harmonic balancer with a differently sized pulley? Is you car pure street or track or somewhere in between? This goes back to what you've said that different situations require different solutions. I hear you loud and clear....mate can you hear me?

 

I re-read Tony's post several times and I think I understand what he's trying to say. Thank you for referring me back to it.

 

As I stated in that post, I am now running an Arizona Z Car cross-flow aluminum radiator, continue to use distilled water with Water Wetter, and installed an LD28 water pump. Recent observations indicate that my problems are solved.....for now. It's winter here (50 to 70 degrees F during the day) so the car will naturally run cooler. However, my temperatures are much more stable when cruising and drop quickly after a hard run.

 

Tony cited Electromotive's car as an example of a high horsepower race vehicle using water and a high pressure cap. Jeffp and Timz are both making over 3 times the power of your N/A L28 and have opted to use Evans due to its higher boiling point. However, that (should based on theory) mean that they are operating at a higher thermal equilibrium due to heat transfer inefficiencies compared to water.

 

Wait, you made a statement that your car is running hotter AFTER swapping out the 160 degree T-stat for a 190 degree T-stat. Did you ever change them back? Of course the car will run hotter in the summer with a 190 degree T-stat.

 

So, with the 190 degree F. thermostat in the engine at the moment, here are some temps at idle after a drive around the block to warm everything up properly.

 

So I think I've picked up a few kilowatts, and it feels quite responsive, tip in is great and off the line performance is good too. Do I leave it like this? I'm just worried about the reliability factor now everything is so much hotter than with the 160 degree F. thermostat.

 

 

Tony, the cap and t-stat are new additions, as are the LD pump and aluminum radiator. Things are looking good.....for now.

[Tony D]

1) But the point I'm trying to make is that regardless if I continue to use the stock 13 psi cap, or if I put a higher pressure cap on, since the cap is never opening up (meaning the radiator (not block) pressure isn't exceeding 13 psi) then what advantage would there be to putting a higher pressure cap on it?

 

2) I'm not challenging that the pressures in the head are higher and this helps prevent nucleate boiling - I understand all that.

3) I'm just challenging the advice I've seen a few times here that putting a higher pressure cap on the radiator would help reduce detonation. I just don't see how that can be if the system has enough capacity (as mine does) to operate without venting with the stock 13 psi cap?

 

To address in turn:

1) You are confusing puking coolant with nucleate boiling. If you aren't puking coolant with a 16 psi cap, it does not mean that you aren't nucleate boiling. You may not be, but because it doesn't get to that point doesn't mean it isn't happening. the higher pressure cap gives nucleate boiling margin just as an oversized radiator core does for normal operating temperature. THEY ARE SEPARATE ISSUES. That you have cooling margin is one thing. The largest radiator and pump in the world will give you tons of margin for cooling. Simple cooling. But PRESSURE is what actually CHANGES THE POINT AT WHERE IT BOILS. Because it's operating at a higher pressure, the chance that nucleate boiling will occur, and go runaway is FARTHER away than with the 16 psi cap.

2) My contention (politely) will be that you dont, follow to point 3 and you should see why.

3) Detonation (or tendency to detonate) due to inadequate cooling of the cylinder head caused by nucleate boiling will be reduced by running the higher pressure cap, because of the margin of increase you get by that increased pressure. Instead of nucleate boiling at 230, now it's 265 (JeffP has recorded this temperature in his engine, BTW!) If you are running a 160 thermostat, it does not mean that everywhere in the engine is 160F! The higher pressure cap will save you from the runaway should conditions get to that point. If your system has capacity in excess, the higher pressure cap on the surface will not benefit you, but the MARGIN it will add if anything ABNORMAL occurs between turns 3 and 4, (two miles from the pits) that you will experience LESS of a problem than you would with a stnadard 16psi cap. Again, you mention 'without venting' and that is an IRRELEVANT item when dealing with nucleate boiling. It does not necessarily happen that it gets hot enough to make ENOUGH steam to cause a venting incident. You CAN be nucleate boiling, and not have a venting issue. My example of pukeover after shutdown was intended to show an EXTREME case of boiling (due to no coolant flow from the PUMP...) The PUMP ADDS PRESSURE in the engine ABOVE the CAP. CAP pressure only matters after shutdown for venting issues. If you are venting during running, you are nucleate boiling (outside of normal thermal expansion of volume of the coolant). If you are not venting, it is not proof that you are not nucleate boiling at portions of your head.

 

For Electramotive, we were told the pressures run in their coolant system were in excess of 2 bar static blanket, and they had modified certian aspects of the cooling system to allow a 300% increase in flow through the engine in order to insure no coolant related issues on their turbo car.

 

Frankly, for an N/A car, this may be hard to understand or justify at a specific output of only 100HP per liter or less. When you are talking about 250 or 330HP per liter, on this engine, with this head and combustion chamber design.... it becomes more clear you aren't in Kansas any more Toto!

[HowlerMonkey]

I forgot to mention in my post on page 1 about extended high rev running causing quick multi-cylinder pinging when stepping into boost that my temperature gauge still read the same temps so it seems in my case that I am getting higher temperatures at the combustion chambers but not the entire engine.

 

Maybe I will hook up the egr and see if it changes things.

[jeffp]

From all of the information I have been able to get, there is still some reasonable doubt as to WHAT EXACTLT is happening in the cylinder head with a high hp engine. I guess it is a situaton of I have not personally observed the occurance.

I know that Electramotive when they were running the car did X and that seemed to take of the heat issues with their builds, so it would also stand to reason that they did discouver the problem, but I have yet to see any REAL imperical data on the subject.

So if I was REALLY wanting to SEE the problem, I vould work a head and install some optical windows in specific parts of the cylinder head and physically SEE what is happening. I don't think I am going to go that far with this.

I am going to follow what electramotive did with their engines and see what happens. IF I am required to do additional testing then that is what will be done.

So for now here is what I am working on:

1) I have looked at the cylinder head, and YES there are points of interest that I will monitor for data. One of the big ones is what is happening to the water/coolant @ the exhaust ports of the head? When you look at the cylinder head, you can see that there is little coolant flow in that portion of the head, and thus the reason/rationale for the bypass flow external to the cylinder head back to the radiator. I have noted an improvement with the #5 & # 6 bypass on my last build. Did this help with high HP? Yes it did, the engine took longer to get hot, and it cooled down much faster. On the road though, on a hot April day in traffic on the freeway, the engine would stay cool, but again as soon as I introduced a load to the engine (A/C turned on) the engine would over heat if I let it. So my first change made improvements but did not solve my problems all together. You need your A/C LOL, it is a good basic test to check the cooling abilities of the engine. I have not reached the point that I can run the A/C in start and stop traffic.

2) the cylinder heads and blocks were designed by different people! If you look at the head you see very good water paths for the spark plugs, not so good water paths for the exhaust ports, and that is where all of the heat is being produced, less the combustion chamber.

Improvements in this area of the head has been addressed by me and I am in the process of testing this change I have made. I just need to get the engine back together, but I have gotten side tracked with a few other areas that have bothered me like fuel delivery. I have upgraded that system as well to 1/2" line and a new magnaflow external fuel pump. I am almos done with the setup, but I was getting a vibration that ran the whole length of the fuel lines. I have to change the pump mounting configuration and change some lines from SS to rubber to insulate the pump vibrations. That will be completed next week.

3) I took a look at the engine blocks, N42 and F54 blocks and noted some SIGNIFICANT changes in the number, placing, and size of the holes in the block. I have had information from electramotive, and from my eaxperience with the HKS laminate gasket. I compared these gaskest to the stock gaskets, and I can tell you the stock gaskets , and the felpro gasket SUCK! the gaskets cover a number of the water cooling paths to the spark plugs, and more importantly the exhaust ports.

I have made changes to the F54 block I am going to test, and if all works out well my mods will be the winning ticket along with some of the other mods mentioned here.

4) I am going to run the LD pump, and a higher system pressure as well. My testing will be with water and water wetter to stop the coorosion of the steel in the negine. Also as a NOTE: check your rust in the block, if you have more then a light rusted coating in the block, I would highly recommend a good hot tank to remove the rust buildup on the cylinders specifically, and then the block itself. Rust is NOT a good heat conductor, and it will cause problems with heating. I have always thought this may be some of the problems with a stock engine that will not stay cool. Also, if you hot tank your block, make sure their tank has the ability to remove the rust, seems now days here in CA, gwetting a REAL hot tank that works is not to easy because of the chemicals used to remove said rust are noe outlawed to use without, you guessed it a costly permit and most shops wont deal with the state in that respect, so what we get now is a fufu hot tank. I found a place in Santa Ana that will do it for ??? $200.00 that is correct 200 dollars because of the chemicals used to remove the rust. Hell the last tank job I got did not remove the rust, and it did not even remove the pain on the block, total waste of time and money for that one, and so goes again my education of the way things are now. You use to get a hot tank fo 40.00 and the block was clean, not anymore.

5) I am going to run a better flowing thermostat, there is a flow restriction with the aftermarket thermostats from MSA and others, you are much better off getting a stock Nissan part at you desired temp if they still sell them that way. The flow through hole is bigger on a stock thermostat then the aftermarket parts. I tested this part, it is a 160 degree part and it can come with the bypass or without the bypass.

6) mods to the block along with a good deck flycut. I will use the laminate HKS gasket as it has more of the cooling holes then the stock gasket. I also milled the gasket in specific areas to flow better. I drilled two more holes in the block for flow around # 3 & # 4 along with some other mods that I don't care to discuss at this juncture.

7) in the future I have been working on a new head gasket that I will be testing later this year to verify a new type configured gasket as a replacement to the HKS part. That is still in the works, so that has been yet another diversion to getting my engine built again quickly.

So that is where I am with this issue. I have a number of changes that I think will be nothing but beneficial, but I need to complete my testing before I outline any changes or recommendations on the matter. I think I have this problem fixed, but I need to get my proto engine completed and give it total hell to get the results of all my changes.

 

Good info guys, all of which I seem to have directly addresed for this next build and some of my own non disclosed changes. I don't want to feel responsible in any way if someones engine goes south because of XXXXX I will not get involved with that.

On a sideline topic, the CSR water pump: I had this designed to stabelize the water flow in the system, regardless of the engine RPM, the pump will operate and pump 24 gallons a minute @ 4psi pressure from the pump outlet. Pumping contained within the engine can then be bumped to a much higher overall system pressure, yet still maintain the overall flow rate of 24 gallons per minute at any engine RPM. The pump has worked well for me, but with all of the mods I am doing I am going to run the LD pump for comparison to see what I get. I like the pump, it has many things that can be done like circulate the water after the engine is dhut down, very beneficial on the dyno. In fact that was the ONLY way I could run so many times in one day on the dyno. I had the engine cooled down in about 5 minutes and was ready to go again. The one thing to KEEP in mind is the current draw of the pump @ idle, most of the stock alternators will heat soak over time and lower the system voltage. That is bad also, you can never set the tune where you want it effectively unless you have a good stable voltage potiental to the injectors, and the larger you go on the injectors the more critical the line voltage becomes. TOTAL PITA! and costly for me at this point with 4 setups tested on the car, well three with the last setup also being tested for this next buld.

I just need to get all of the ground work completed and do the testing. Testing will be quick and I wll know if I wasted my time and money for all of these new changes, they aint cheap.

[BRAAP]

Great info Jeff thanks. Regarding the sight windows, something like this? I have two styles, one with perforated shield, the other just glass.

 

Plain glass;

 

With the perf;

 

Regarding the FelPro gaskets and it's covering of ports that should not be covered, I am assuming you are talking about the L28E gasket when used on the F54 blocks. have you looked at the other Felpro head gasket for the earlier L28 to see how its coolant passages line up on the later block, (N42 gasket on a F54 block)? I had both gaskets here at one time with both an N42 and an F54 block and was going to map out the coolant passages that both gaskets covered and uncovered for both blocks, then swap them to see what was changed and if it was even feasible to swap gaskets....

 

Jeff and/or Tony, do you feel it is worth investigating or does it cover too many of the vital areas regardless? I think I still have both blocks here, I can get both gaskets again?....

[FlatBlack]

Jeff and/or Tony, do you feel it is worth investigating or does it cover too many of the vital areas regardless? I think I still have both blocks here, I can get both gaskets again?....

 

I also have a N42 short block, and I can pop off the head on my F54/P90A if you can't get the time, BRAAP.

 

I have an extra Fel-pro sitting around for some reason so if I can help, let me know.

 

By the way, on the packaging the Fel-pro lists the L28 gasket for all years, 75-83.

 

*edit* I took a look at the Fel-Pro and compared it to this picture of my P79. This is obviously just where the head coolant passages are blocked but I guess that's the important part [i'm at home and all I have is this crappy MS Paint, sorry for the quality]

 

The red circles indicate where there are holes in the head [P79] but not in the gasket, blue indicates holes in the gasket but not in the head.

 

 

*edit* Oh. Monzter already did that. http://forums.hybridz.org/showpost.php?p=841826&postcount=9

[BRAAP]

For what it's worth, Felpro offers 2 different head gaskets for the L28, each is respective to the block and its different coolant passages on the deck surface as Jeff mentioned, N42 vs F54.

 

While I had both in hand this last summer, RTz and myself were casually noting the distinct differences between the two head gaskets and the coolant passages when set next to each other, but never took any further than that. initial inspection didn't reveal anything that stood out as "ah-hah", just that they were both quite different in the coolant passages...

 

Out of the FelPro catalog;

Edited January 9, 2010 by BRAAP

[FlatBlack]

I was unaware, I ordered a gasket for my 81 F54 at a AutoZone and that's what they ordered from Fel-Pro, since it had L24,L26,L28, and L28ET written on it I assumed they only had one.

 

Want me to delete the above post? It doesn't really contribute to the thread :/

 

Anyways, I'm closely watching this and the other cooling options thread, I'd like to do some modifying if I rebuild my L28ET this summer.

[BRAAP]

I was unaware, I ordered a gasket for my 81 F54 at a AutoZone and that's what they ordered from Fel-Pro, since it had L24,L26,L28, and L28ET written on it I assumed they only had one.

 

Want me to delete the above post? It doesn't really contribute to the thread :/

 

Anyways, I'm closely watching this and the other cooling options thread, I'd like to do some modifying if I rebuild my L28ET this summer.

 

Mat,

No worries, its all good. You can leave it, I'm sure many others were unaware as well. As we look further and compare the 2 gaskets on the 2 different blocks, we just may find that using the N42 gasket on the F54 block and/or vice versa could be very detrimental to coolant flow, which might explain part of the hypersensitivity to detonation that we experience, or the other way around where using the opposite gasket on one fo the blocks might help flow through the head.

 

Waiting on JeffP and TonyD's input as I get the impression they both have looked into this a lot deeper than the rest of us.

[BRAAP]

Just went out to the shop, I do have one each of the Felpro head gaskets, (8799PT and a 21157PT-1), also a custom Clark Copper head gasket, and one each of the blocks, F54 and N42. I'll go out and spend some time looking them over, pending approval from the owner of the N-42 short block to publicly post pics, I'll post pics as well.

Edited January 9, 2010 by BRAAP

[ozconnection]

I sounds like we should be more circumspect in our head gasket choices?

 

I must admit, my last HG may have been some el cheapo that's probably blocking some critical coolant passageway and thus allowing nucleate boiling somewhere. It doesn't overheat, even with the A/C on, but it does rattle with 8.3:1 compression @ 38 degrees total!!

 

(Hmmmm, putting on that Y70 head is a bit closer because we're all a bit wiser.........thanks).

 

Yes Paul, I'm looking forward to seeing your pictures as well.

 

Sticky, anyone?