unclematt

Hi,
I am curious if you have ever heard of anyone applying diamond-like-carbon to their rotor housing friction surfaces? Diamond-like-carbon (or DLC) supposedly reduces friction and requires little in the way of lubrication to maintain its anti-friction properties. Moller uses a high tempcoating from NASA on his rotor housings after first applying a coating of zirconia to the cumbustion part of the rotor housing, but I am curious if anyone has tried DLC? If not DLC, has anyone tried to apply advanced coatings to their rotor housings to reduce friction, or contain heat, with any success?

Blake

I can't honestly answer this one. The person to ask would probably be Marc at JHB Performance, who is the coating expert. I would suspect that if anyone is trying it, they are keeping it under wraps.

unclematt

forive my unfortunate misspelling of "combustion" in the OP.



If anyone has tried DLC in an engine, I would love to hear about it. I will contact Marc as well and get his take on this coating.

I have read Moller's patents on coatings and would like to explore alternatives to his coating choices. However, when these coatings insulate the rotor housing from heat, the exhaust gases of course become much hotter. Currently Moller is supposedly trying to create a "compound" rotary engine where one rotor is used for combustion, and then a second rotor scavenges the energy remaining in the high temperature exhaust gas. I wonder how difficult it would be to fabricate an engine based on this concept?

unclematt

Here is a link to the patent on Moller's 2 coating system.

locopr1

I finally got my engine apart to rebuild it. It had a major oil leak into the rear rotor chamber. I bought the car with the engine broken. Interesting thing was that ALL FOUR oil control rings were damaged in the rear rotor. I dont believe in coincidences. What could have happened to cause this? The car was sitting for about ten years. The engine parts are in remarkable shape for a car that was sitting so long, but I will post pictures to see if you think they are reusable. Engine had only 70K. Would love to get this 79 on the road again soon!

LOVE THIS THREAD!

rotativo21

Blake, at the beggining of this thread (page 1), you stated that a 4 rotor can be purcahsed from pineapple racing. I can't find a listing on the site for the 4 rotor motor.

Blake

Well, it's not exactly a stocked item, if you know what I mean. If you are interested, email Rob Golden <rob@pineappleracing.com>. However, please DO NOT contact him if you are not serious, lack the budget (if you have to ask...) or are price shopping.

apexFD

Hey Blake,



Ive being kicking around the forums and taking info from here and there like always, my FD is supposed to land from japan in 4-5 weeks and ive being doing a lot of research on the 3rd gen in general.

I think this may have being covered but here goes..

I have read that their waterseals last from 50-75 000 miles.... or more depending on all of the variables. I am just wondering if these poor results are because of the materials used in the stock FD water seals, or if this is just the nature of the rew?

And your water seals are obviously the only way to go over the stock seals.. do they moot the problem of the rew blowing water seals at 50-75k??

And what are some of the preventative measures that can help the longevity of the stock water seals, so far i know that keeping the engine cool is a big factor.


Thanks,


=Ben

apexFD

In addition to my above question... Does the use of evans NPG+ coolant show any relation to longer STOCK water seal life? What about evans NPG+ coolant on pineapple water seals?

I have being debating the benifits vs cost of this product. However because pineapple recomends it i am 80% convinced already.



Thanks a lot Blake,


=Ben

Blake

Sorry, I hadn't noticed your earlier question. The water jacket o-rings on the REW are the same material as the earlier engines. The shorter life expectancy of the REW is due to a number of factors, including heat, but part of the story may be how they are maintained and -- equally critical -- how they are driven. Cars like these are usually play toys, which don't see many long, easy commuting miles, so you get more heat cycles for the mileage. Or if they are daily drivers, the owners won't let them warm up fully before getting on the boost because they are late for work or just like the power. The maintenance is a pain, as I am sure you know, and qualified mechanics (even at the dealer) are hard to find, so maintenance was not as good as it could be. But there is still some engineering culpability on Mazda's part because they could have done more to make it bulletproof, in my opinion. If it were an Italian sports car we would all be raving about the reliability, but it's Japanese and the expectations are much different.

Another thing to consider is that the FD is the first RX-7 without a mechanical clutch fan. While they get a bad rap for sapping performance, the real benefits of the clutch fan are that they (1) pull HUGE amounts of air and (2) because of the progressive lock-up, the volume is controlled according to need and you get less coolant temp fluctuation. Electric fans basically have one or two speeds, or are off entirely, resulting in more variability in coolant temps. Fans are theoretically only important at lower speeds or at stops, where there is little or no natural airflow, but in such a packed engine bay with questionable ventalation, that can be a life-shortening factor. And don't forget the plastic air separation tank that can rupture and instantaneously cause a serious overheating problem.

What we have seen on performance FDs is a tendancy to build up localized hotspots around the spark plugs. Because the coolant flowing in this area is overtaxed, localized nucleate boiling effectively insulates the area, causing a vicious, progressive overheating that is not detected until it is too late. This is because the insulated area cannot transfer the heat as effectively to the coolant, so the coolant temps lag behind as the hotspot grows. By the time you see the temperature spike, the damage is done. It might not shrink the housings, but the coolant seals can get cooked pretty good. We also see a lot of REW and TII housings with cracked trailing spark plug holes, which suck coolant. There are usually other contributing factors, but we believe this is the mechanism: The coolant is overtaxed on the hottest parts of the motor resulting in a progressive overheating. Now, if the coolant temps were better controlled by, say, upgrading the radiator and improving the flow of air through it, that may get your coolant back to the point it can handle the hotspots. But it is still marginal at best. The solution, as we see it, is to improve the coolant. The Non-aqueous Propylene Glycol (NPG) product by Evan Cooling doesn't boil until 375ºF at ZERO PSI! Compare that to traditional Ethylene Glycol and Water (EGW) that boils around 225ºF. Even with pressure, it is dangerously close to boiling in the system. If the system temp creeps up and the hot spots are flaring up, you get a situation where the coolant temps will no longer reflect what is happening inside the engine and the coolant is doing little to control the runaway situation. With the Evans, we believe it is more effectively bathing the hotspots and pulling out the heat. At any rate, the engine seem to like it and we can add more ignition timing without melting down the block. The coolant temps will tend to be a bit elevated, partially due to the properies of NPG (it gains more temp per calorie consumed) but also because in those situations it is actually pulling out more heat. We are not concerned with coolant temp; we only care about engine hotspot temps. If you can control the hotspots, you have mastered the problem. Also, the hotter the coolant, the more effective the radiator becomes (bigger temp differential). We have has a lot of impractical engineers claim the specs can't support what we are seeing, but they seem to forget that when the theory doesn't match the reality, you throw out the theory. We are NPG believers. As for the longevity of NPG, it is basically indefinite so long as it is not contaminated. It's tricky to install because you must have ALL the water out of the system, and because of its low surface tention, it wants to sneek out of places that you may never have had problems before. The reason it can last indefinitely is because there is no water, so there is less need for corrosion inhibiting addatives found in EGW, which eventually fail and require replacing. NOTE: NPG is not that nasty "lifetime" orange coolant that has such a bad rap. That stuff used water and therefore required a LOT of addatives to meet the lifetime expectation. It is the addatives that are suspected of causing the problems.

With all that said, opting to use NPG is not necessarily an easy decision. As I said, it is a pain to install because of the need to keep it uncontaminated by water. But it is also not available at any autoparts store that I am aware of, so you need to carry extra in case of emergency. And even if it does last indefinitely, it is a pain to capture without contamination so you can reuse it after performing maintenance that requires draining the coolant. The cost is also almost $35/gal plus shipping from wherever you can find it. Don't bother ordering it from us. We stopped stocking it recently because Evans won't cut us a very good price unless we buy an entire pallet of the stuff and even then, the profit margin is too low to contemplate tying up all that capital. Most of our customers for it have been diesel truck owners, as that is the market the product was intended for in the first place and where it's benefits are widely known. We only stock enough for personal use, because we believe in it.

As for our HD Water Seals, the original intent was to create a water seal that (1) could take higher temps without failing and (2) be reusable if there was reason to get back into the engine for a freshen-up -- mostly for racing where we inspect frequently, but also for street performance motors that may need periodic fixing from over-ambitious tuning, nuts dropped down the intake or whatever. Often, we build a motor destined for ceramic apex seals using conventional metallic seals so we can get the tuning done as well as accomplish some of the break-in before pulling it back apart to install the expensive ceramic seals. It's nice to be able to pull the block apart and not have to replace the water seals every time. The longevity is not really known definitively, except that in seven years of testing on the street and track and about three additional years of selling to the public, we have yet to hear of a failure. We have many motors using these seals that are well past our 5 year warrantee, so we have no reason to think they will suddenly fail at a given mileage. Rob would have a better idea of which engines have the highest mileage. Give him a call if you want to ask more about the testing. At any rate, they seem to last and last. However, they won't stop you from overheating the block to the point the housing shrink/warp and leak around them. We have seen cases where the housings were SERIOUSLY overheated resulting in damaged housings yet the HD Water Seals were still intact and able to be reused. But I don't want to make any specific longevity claims because without the resources to test them scientifically, as Mazda might do, we have to rely on years and years and years of field testing. Ten years down, hundreds of motors using them, but that is still too early and too small a sample to go around making claims. A lot of these guys don't put a lot of miles on their toys, so it might be a while before we see a large sample of 100K+ engines with HD Water Seals. All we know is that they are doing a hell of a job so far, so we have no problem warranting the engines we build for 5 years when using these seals and have no reason to believe they won't last as long or longer than the stock seals when properly installed.

GoodfellaFD3S

iTrader: (213)

Very informative post Blake, thanks

apexFD

Wow Blake, thanks for the exellent response.


I am yet to receive my FD from Japan (2 weeks left!!) i have being hard at work generating a tune up/reliability mod list and a maintenance schedule for it, as I want to take great care of it as I do with all my vehicles. I drive my vehicles respectfully, ie. <3000rpm/<0psi until FULLY warm/reducing short trips/ and do ALL of the work myself, except rebuilding the engine, I do not have the resources to properly undertake something like that and complete it to my standards.

Anyways, I really want to focus on cooling for my FD. All the information I have read predominantly points to cooling. I have being sketching out custom IC/Rad designs with custom ducting to maximize the cooling efficiency and maximize the amount of air getting to the IC/Rad/Oil coolers. Then with a superior coolant like NPG i hope this will equal in long waterseal life and an over all healthy engine.

I mean one does have to be chemically inclined to design superior coolants, however a custom radiator (cooland/oil/ic) set up does not require a lot of specialized knowledge. So the combination of both is obviously the way to go. I mean in reality mounting a radiator/IC then fabricating ducting to direct air into then and a shroud/fan set up is NOT rocket science… I would much rather make my own then buy a $2500 ‘kit’ with an overkill IC and no ducting.


As far as the NPG coolant goes, the only grey areas I see with this coolant are the following...

1) "low surface tention, it wants to sneek out of places that you may never have had problems before"

More prone to leaking through microscopic gaps?

However running at 0psi might be a blessing in disguise for NPG compared to normal coolant. Ethylene Glycol may have a higher surface tension but the fact that it runs at 6-10psi (if my guess is correct), hence the force of volumetric pressure pushing the coolant into the gap, may make both coolants have a similar leaking ability at operating temperature. We cannot forget that the general trend of surface tension is to DECREASE with INCREASE in temperature; every liquid having a different constant ‘k’ of decrease based on properties. As you said NPG will run at a higher temperature because it absorbs more heat from the engine, this would lower its surface tension which is bad for leaks, but good for thermal conductivity. Also as you stated a higher temperature differential in the radiator is better anyways. Concentration also plays a factor, but with no numbers to work with its hard to asses its involvement. But ya you are totally right, normal coolant operated very close to its boiling point, in fact the pressure it operates at is what gives EGW a higher boiling point, so in a way it relies on pressure to enhance its performance… and obviously the pressure throughout the entire cooling system will NOT be the same, higher pressure will be found at the ‘hot spots’ and the coolant will create more water vapor and run at a higher pressure still. However the hotspot will only get hotter because it is a bit of a positive feedback loop; the engine has to produce heat to increase the pressure to increase the coolant boiling point… haha, I want NPG.

As far as the coolants ability to leak, I think that the net force on both coolants, with all factors taken into account, will be similar but not identical -obviously-. EGW will have a 6-8psi (remember hotter=more pressure) force pushing it into the gap, whereas NPG would only have a lower surface tension working against it in terms of leak ability. This would be the only obvious difference between both coolants as they both experience gravity/capillary action/pressure cooling system flowing. And besides a low surface tension is more favorable for cooling anyways because it will form smaller bubbles if it produces any at all.


But i mean, if the water seals are prone to leaking because of a slightly lower surface tension anyways... then the use of EGW at 6-10psi and a subsequent higher water seal temperature/fatigue -because EGW cannot absord as much heat from the housings and surrounding areas, therefore they will be a higher operating temperature- then certainly EGW cannot be better for the seals then NPG. But this is comming from a 20 year old with no first hand experience...



I would love to compare the chemical properties with actual numbers, but i doubt NPG would redily give me the specs. They would charge me $35/letter instead of per gallon haha.



2) A pain to install.


Obviously the best time to introduce NPG would be after a rebuild, with NO contamination. But even still, what about the heater core and the rest of the obscure coolant lines that are either below the drain plug mark of simply un-drainable?


Im sure compressed air would help, but could there be any better way to make sure that 100% of contaminates are eliminated? And what about the coolant/gunk that will naturally adhere to the walls of the coolant passages/hoses? You would almost have to run water through the entire system then a LOT of compressed air to dry everything off internally… Even then im sure solid gunk would still be present… hmm. Why didn’t Mazda use this coolant to begin with!



Anyways, thanks again for the excellent information as always. I want to run this coolant now, ill just have to figure out a good way to eliminate contaminates.




=Ben

elwood

iTrader: (1)

I converted to Evans NPG+ on my last rebuild, and it's not that difficult if you take the engine out of the car and disassemble it. According to Evans, removing all the coolant isn't nearly as important as removing all the water. Even so, I flushed everything with water, then rigged a hair dryer to blow though the hoses and through the heater core. I did the same thing with the radiator. After a few hours of this, I felt confident they were both bone dry.

mustang_kicker

i recently bought an 89 rx7 gtu (n/a) and a stuck apex seal trashed the rear housing. i found a 89-92 turbo engine for 1400 bux and the description claims it comes with the ecu and everything to do the n/a - turbo swap. what all would be needed to do this swap ?

Uncle Hungry

iTrader: (2)

Here's one for you. I am in the process of rebuilding my 13b rew from my 93 r1. I just want to make sure i'm doing this correctly.I've just begun the measuring process and here's what I get for the max rotor width in 3 spots as per the fsm. Apex a = 3.1996 apex b = 3.2073 apex c = 3.2164 . Then I measure the specified spot on the rotor housing and get 3.1495. Now taking the widest measurement of the rotor which was 3.2164 and subtracting the width of the housing of 3.1495 leaving me with a clearance of .0669. Acording to the fsm the minimum clearance is .0039. I thought the rotor housing was supposed to be wider than the rotor, is this not the case? It also says the standard measurement is between .0047 and .083, is it possible for me to be that far out or did I just read it wrong? I know that's alot of info but I really appreciate the help.

Uncle Hungry

iTrader: (2)

I just called pineapple and couldn't ask for a more thourough explanation for my problem, pineapple racing is awesome!!

Uncle Hungry

iTrader: (2)

One more, Rob told me last night but I forgot.I can't seem to find the spec for land petrusion on the rotor. The only spec I found is side seal and oil seal petrusion. This is a 93 fd 13b rew by the way.

charlies7

iTrader: (4)

are you guys going to have a large streetport template soon, for a REW??

Blake

No, but what I should do is re-name the "medium" template as a "large" so people won't imagine there is a larger porting template we will eventually sell. An honest-to-God "Large" street port is out of the realm of skill for those who are not capable of making their own template. In other words, if you could do it you would not need a template. The "medium" *is* a "large" for DIYers. Even if we believed people could do it, 99.9% of them would be going backwards on performance because (1) even if they didn't blow through the plates they would not get the bowl shape and other contours right and (2) bigger is not always better. If you don't have the WHOLE system to support a larger port, you will get crappy performance. Perhaps the peak power will be okay, but you lose a lot of torque needlessly. That's my opinion. Perhaps some day I will bend to the will of the masses, but not today. I am honestly on the verge of renaming the "medium" a "large" and then calling the very extreme jobs we do on some customer motors an "extra-large" or some such nonsense. Sorry to rant.

cp1

Hi Blake,

i was just wondering if the rx8 renesis engine has the same transmission mounting pattern is the same as the manual 13B-REW from a 3rd Gen rx7?

Im asking because it has been something ive been considering swapping into my rx7, have you had anyone ask you a about the pros or cons of doing this and what has been your advice to them?

Blake

Yes, it's the same for all the rotary engines. Rob put one in his daily driver REPU. I would not recommend on for an FD. The durability is a questionmark and the ratios are better suited to an NA.

apexFD

Hi Blake,



Im wondering what your thoughts are on premix.

From what i have read the most popular ratios are 128:1 WITHOUT OMP, and 256:1 WITH OMP.


I ran a good quality 2 stroke oil in my FC and it seemed to like it very much. Smoke on start up was rare and exhaust didnt seem to smoke at WOT.


Anyways, just a short question.


Thanks,


=Ben

cp1

Hi Blake

I remember seeing an article sometime ago which i believe was on the pineappleracing website about removing all of the emissions cleaning up the vacuum hoses and wiring on the 3rd gen cars. It also described how to convert the sequential setup into a non-sequential one at the same time. Basically it stressed that there was no point in doing just one or the other, now that im looking for that exact article and cant find it im wondering if you could go through the specific steps necessary to do this?

Uncle Hungry

iTrader: (2)

R.I.P Blake...........

apexFD

I have just found out of Blakes passing...


I am speechless.


Rest in Peace Blake...



=Ben