What's overheating is the water-based coolant. Evans NPG+ (nonaquaeous propylene glycol +) boils at 375 F @ zero psi cooling system pressure. From what I've read about Evans, it's the localized boiling from water-based coolants and the resultant hot spots are what cause rotor housing warping and detonation leading to either water seal failure, or apex seal failure. From the Evans threads I've read, not one FD owner using Evans has reported an engine failure directly related to the Evans coolant. With FMIC and hot summer open lapping events, my cooling options are limited to switching to Evans NPG+.

 

That's true to a point Manny but the laws of physics clearly state that aluminum expands at a different rate than iron. That expansion rate becomes critical above 240 degrees or so which allows for normal tolerances in several key areas to become greater than the engine can tolerate leading to failure. Could be the o-rings, could be detonation, could be seal clearance. Maybe it shows in increased wear on the side plates. It isn't advisable to run a rotary that hot no matter what coolant system you're using. And if the water temps are that hot, the oil temps are probably in the critical range too. 2/3 of all cooling in a rotary is done by oil, not the cooling system. One can relate it to good tuning. There's no substitue. Same with the cooling system. There's no substitute for keeping the coolant below a certain temperature. If Evans helps to do that, great. But I think it would be irresponsible for people to believe that you can run a rotary hotter just because one is using Evans. I do acknowledge Evans may stop localized boiling. It's just not a cure-all for a rotary that runs hot.

 

My motor only runs that hot, b/c I drive so fast on track. If I drive like "Miss Daisy", I'll probably be ok. Being "fast" is a double-edged sword LOL

 

Very, very true! :-)

 

Process have begun.. I've pretty much taken most of the stuff of today.. Tomorrow, I should be ready to pull my engine..

I've decided that I'm going to ditch my AC.. Also, found a way to channel some air to my radiator.

Here are some pics..

 

Nothing really.. My 5th gear synchro is gone and also RZ have longer 5th gear.. I've heard they are stronger.. but I don't think so..

 

HERBLENNY, sorry about that engine...hopefully you be kicking back them gears soon!

ps..love the exterior, what you have on their??

 

Where did you get your factual basis for this assertion: that the expansion rate for aluminum is critical above 240 degrees or so? In other words, above 240 degrees F, the expansion rate of aluminum changes greatly in relation to cast iron?

I have never heard of this, 240 F being a critical temp for aluminum. So if you can't back it up with some reference, I'm going to call it for what it is: cow manure that you pulled out of your ***.

 

that has been me so many times its like deja trois or something....i feel for ya man.

 

Phil, sorry to hear about your motor. What kind of port are u going to get on the new motor? Are u going single are u still keeping the twins. Keep the AC. Your going to regret it living down there. If u need anything just let me know. Later!

 

The motor is already built he just got to break it in and drop it in.

 

Awwww, come on guys....swaping out the engine is a right of passage for any hardcore RX7 owner hahahahaha


Sucks that it happened so far from home though. At least you already have the replacement ready to go in.

 

Vila,

Good to hear from you.. Its large street port with custom porting that my builder did.. Eventually I'll be putting a single in.. but for now, its going to be stock twins.. I have few sets of stocks so, I'm going to push 14-16lbs... until they blow out.. Its too late about AC>. I've removed all the lines and ready to pull the compressor.. I haven't used AC in past 2 years..

 

Actually--this is a fair question. RTS3GEN has seen 265 F with Evans @ Homestead. Jack has seen at least 265 F @ Watkins Glen with Evans.

 

Poo poo man, from Roger Mandeville when he spoke to a group of us at MADS several years back concerning engine building. But hey, you know more than him and apparently me. I'll spell it out for you since you apparently like to be spoon fed... it's not "critical" as in aluminum will fail...it's critical in terms of what the expansion rates can do to clearances within the motor in relation to their iron counterparts. There's also this little thing called warpage. Why do you think motors fail when they get too hot? How many stories have you heard concerning a rotary that was overheated once and was toast? But hey, reading most of your poo poo posts, you're a friggin expert. Tell you what...call a reputable rotary engine building shop (other than Pineapple) and ask them. Do your own friggin homework. I hate spoon feeding.

Who's RTS3GEN? Any idea what track group he runs with? I've seen as high as 105C at Moroso but never higher. I don't see very many third gens down here at the track which is why I ask. Anyhoo, one only has to look at the temperatures Mazda designed the engine to run at and what temps they deem critical. 265F is way over that limit and there's no way in hell I would continue to run a car on the track seeing those temps on my PFC (or whatever gauge one is using). You're asking for trouble plain and simple. If one believes the engine is running in a more optimal condition at 265F versus say 210, I'd love to hear why.

 

hmmmmm....im guessing you got on OEM front bumpers and border racing fenders...So this engine you have on the side; how much it cost you if you dont mind telling... And who's the builder?
-iNjen 7

 

So you've no factual basis for your second hand hearsay of the gospel.

Just b/c it supposedly came out of the mouth of Mandeville, it's supposed to be kosher?

And just blowing me off by referring to other unspecified tuners(except Pineapple) just shows that you're lazy intellectually. When in doubt about your own bullshit, just start dropping names. Works like a charm for newbies around here.


As to your half-assed mishmash explanation of "warpage" : Warpage is caused when the local temperature of the metal is not being controlled by the coolant. As long as the local temperature of the metals, both Al and Iron, are controlled by transfer of heat energy to the coolant, i.e, the rate of change in temperature over time, isn't out of control, it is ok to run at an average temperature of 240F. This is true notwithstanding that Aluminum has an expansion rate of 1.7 times that of cast iron from room temperature to about 800F.

My 4 cylinder cast iron block Al head 1999 Camry runs at around 230-240F average coolant temperature in traffic. It runs this high for OBDII compliance. It has done so for the last 50,000 miles. My 2002 Toyota mini van runs even higher temperature than this. And these are on Toyota red coolant water mixture, not Evans. Why hasn't it failed?

My buddy 1993 VR6 Passat runs at 240F-250F (I'm not sure if it's all Al though) for the last 80,000 miles. Same emission reason and on VW orange water coolant with a 21 psi cap. Why hasn't it failed?

Consider me the bullshit-artist patrol around here ...

 

Seriously...do a search to discover why it's not healthy to run a rotary at those temperatures. I said anyone but Pineapple which you would have understood if you realized that Rob is the one that pushes and sells Evans (but certainly not the only). Lazy intellectually...no, actually I've seen enough of your posts, banter and argument (you're supposedly a lawyer?) that quite frankly, you're not worth the effort. You spend more time harassing people on the list and flaunting your $200/hr rate to prop up your inflated ego instead of contributing to the rotary community with actual, personal knowledge. If you would like to run your engine at those temperatures on the track, be my guest. Really...how f*cking hard is it to look up the expansion rate of aluminum on the internet? What, two seconds?

But again, talk to an engine builder. I've taken the time to talk to many over the years. Perhaps talk to Cam Worth at Pettit. Maybe Nick Riefner at N-Tech Engineering. Ask Cam what temps he runs the race cars at. Have you ever taken the time to learn how to build your own engine, the work it takes, the careful clearances (emphasis on clearances)? I suspect not. Do I have personal knowledge, as in my own engine failing due to overheating? No I don't because I've engineered my oil and cooling system accordingly. There's a reason why the stock ECU goes into limp mode at a certain temp. There's a reason why the stock piece of crap engine gauge heads north at a Mazda-determined temperature and not sooner. Just look at the stock ECU's fan logic which dictates the second, high speed fan comes on at 210 degrees F. But wait..I'm just making stuff up.

The interface between a cylinder head and block is quite a bit different from a housing and plate. A rotary motor is quite different from a piston engine when it comes to cooling needs, optimal temperatures, etc...You cannot compare the two. The Renesis doesn't run at 240F in normal operation and it's OBD-II compliant. Take into account tension bolt torque differences around the circumference of the rotary motor. When did a Camry come with a rotary? Must be an interesting car. And what sort of temperature gauge do you have on said Camry? The OBDII compliance...this you know yourself how? I'm wondering what that catalytic converter is stuck in there for....What factual information do you have to say that running a rotary motor at 240 degrees fahrenheit coolant temps at the temp sender is healthy for the motor? What, if any, hands-on experience do you have with anything relating to this topic other than you apparently drive a rotary-powered vehicle and like to hear yourself talk?

And let me ask you this...at what temperature do things get out of control since you're such an expert. Which allows for greater heat transferrence by volume, water or Evans? I dunno...maybe Roger's engine builder sat there and lied to everyone for two hours. I guess anything could happen. But the thing is, it's not just Roger's guys I've heard this from. It's other engine builders as well. And again, high coolant temps means oil temps aren't in check either. Remember that a majority of the cooling in a rotary is done by oil. But Evans will solve that, right? Again, I'm not doubting the fact Evans boils at a higher temperature. I'm simply saying there is an optimal temperature range for the rotary engine and running over that temp, especially under heavy load for an extended period of time, will shorten engine life and could lead to catastrophic failure. I post this for people who have cars which run hotter than normal and believe by simply adding Evan, their problems will be solved. It's called covering your bases and making sure everything is in perfect working order.

Heresay...this entire list is heresay. What's your point? Do I trust Manny when he gives advice on alignment for a particular wheel tire setup? I do. Going by your logic however, it's just heresay and therefore invalid. Do you really believe that to be true?

 

>>>Seriously...do a search to discover why it's not healthy to run a rotary at those temperatures. I said anyone but Pineapple which you would have understood if you realized that Rob is the one that pushes and sells Evans (but certainly not the only). Lazy intellectually...no, actually I've seen enough of your posts, banter and argument (you're supposedly a lawyer?) that quite frankly, you're not worth the effort. You spend more time harassing people on the list and flaunting your $200/hr rate to prop up your inflated ego instead of contributing to the rotary community with actual, personal knowledge. If you would like to run your engine at those temperatures on the track, be my guest. Really...how f*cking hard is it to look up the expansion rate of aluminum on the internet? What, two seconds?

So what if I have an overinflated ego? It must be the Viagra (but that's another story) The issue here is that you threw in an assertion that isn't applicable when running evans NPG+. And you state this assertion with some authority. I challenged you on it and you throw a hissy fit.

>>>>But again, talk to an engine builder. I've taken the time to talk to many over the years. Perhaps talk to Cam Worth at Pettit. Maybe Nick Riefner at N-Tech Engineering. Ask Cam what temps he runs the race cars at. Have you ever taken the time to learn how to build your own engine, the work it takes, the careful clearances (emphasis on clearances)? I suspect not. Do I have personal knowledge, as in my own engine failing due to overheating? No I don't because I've engineered my oil and cooling system accordingly. There's a reason why the stock ECU goes into limp mode at a certain temp. There's a reason why the stock piece of crap engine gauge heads north at a Mazda-determined temperature and not sooner. Just look at the stock ECU's fan logic which dictates the second, high speed fan comes on at 210 degrees F. But wait..I'm just making stuff up.

What is this paragraph about?? Engine builders as the word of the rotary god and then segue into the ecu gauge??

Do you realize that the stock gauge is plumbed directly into the block so that it senses metal temperature? As such, it doesn't really correspond 1:1 with coolant temperature once your coolant starts boiling. My VDO coolant temperature is mounted near the same location as the thermosensor below the filler neck. It and the PFC gauge have gone to 260f on at least one occassion running Evans NPG+ and my stock gauge never moved. In contrast, with EG and water, when my last motor started going, I could see the coolant gauge at 230F yet the dash gauge went to "H". That was my first inkling that I had an engine failure on my hand.

>>The interface between a cylinder head and block is quite a bit different from a housing and plate. A rotary motor is quite different from a piston engine when it comes to cooling needs, optimal temperatures, etc...You cannot compare the two. The Renesis doesn't run at 240F in normal operation and it's OBD-II compliant. Take into account tension bolt torque differences around the circumference of the rotary motor. When did a Camry come with a rotary? Must be an interesting car. And what sort of temperature gauge do you have on said Camry? The OBDII compliance...this you know yourself how? I'm wondering what that catalytic converter is stuck in there for....What factual information do you have to say that running a rotary motor at 240 degrees fahrenheit coolant temps at the temp sender is healthy for the motor? What, if any, hands-on experience do you have with anything relating to this topic other than you apparently drive a rotary-powered vehicle and like to hear yourself talk?

The above rant is so twisted and convoluted that I wouldn't even want to unwind it. You are the one who lectured everyone on never to run 240 F b/c that is the critical temperature. I challenged that assertion but you never provided any factual basis for not running 240F or above WITH evans NPG+. We still don't have an answer from you because all the wisdoms from the engine builders are for EG and water, not evans NPG+. Rather than sitting around spouting my mouth off I am putting my money where my mouth is by running Evans NPG.

>>>And let me ask you this...at what temperature do things get out of control since you're such an expert. Which allows for greater heat transferrence by volume, water or Evans? I dunno...maybe Roger's engine builder sat there and lied to everyone for two hours. I guess anything could happen. But the thing is, it's not just Roger's guys I've heard this from. It's other engine builders as well. And again, high coolant temps means oil temps aren't in check either. Remember that a majority of the cooling in a rotary is done by oil. But Evans will solve that, right? Again, I'm not doubting the fact Evans boils at a higher temperature. I'm simply saying there is an optimal temperature range for the rotary engine and running over that temp, especially under heavy load for an extended period of time, will shorten engine life and could lead to catastrophic failure. I post this for people who have cars which run hotter than normal and believe by simply adding Evan, their problems will be solved. It's called covering your bases and making sure everything is in perfect working order.

To answer your question: the optimal range for the FD running EG and water should be less than 240F but yet how do you explain two motors that never reached 240F at any point in their lives died b/c of the o-ring failure at 50K miles? The reman that I'm running now sees 240F in traffic daily with AC on full and with Evans NPG+ and I see no ill effect. It has gone as high as 260F with no ill effect (and mind you the Mazda gauge never moved from its middle position). I thrashed my car against a Ducati 996 in 90F for 15 minutes with the coolant temp showing 240F with no ill effect.


>>>>Heresay...this entire list is eresay. What's your point? Do I trust Manny when he gives advice on alignment for a particular wheel tire setup? I do. Going by your logic however, it's just heresay and therefore invalid. Do you really believe that to be true?

It is hearsay when the assertion itself can't be quickly confirmed with common knowledge. For example, when Manny tells you to run -10 deg negative rear camber, do you run off and do it or ask him on what factual basis he has for running this type of camber?

In your post, your assertion didn't make any sense with what I know of high performance engines so I challenged you on it. Rather than giving a coherent answer you throw a web-rage.

 

I guess I should put my 2 cents into this whole NPG+ vs. water vs. EG..

Only thing that gets me about NPG+ is the whole heat transfer rate. I read other discussion thread and I believe that is the reason for higher running temp.. Far as running high temp is good or bad.. I believe (with my limited knowledge) that its not good to run high temps.. I've heard that it will increase chance of detonation, warping of housing due to change in expansion rate, warping of e shaft, etc.. Far as I know about rotary engine is that tolorance level is very small when it comes to rebuilt.. so small amount of change (warping) could mean reusing your old housing or getting a new one.. I'm hoping that my new set up will avoid my previous mistakes.. but I still can't justify using NPG+ knowing my car will run hotter.. and having higher boiling temp means safer.. I just can't quite grasp that concept..

 

NPG+ isn't for everyone. In my case, I had two motors failed from o-ring failure when none of the motors had ever overheated, i.e., coolant temp greater than 240F. Short of changing my driving habits, I elected to experiment with NPG+.

My hunch is that the twins caused the failure because they store so much heat during running and after shutdown that it caused the housing to warp over time.

It's still too early for me to tell (3000 miles on the motor) but up to now, it has met my expectations: low pressure, no overheating, no corrosion, large headroom before loss of nucleate boiling. The temperature gauge does read 10-15 degrees F higher but that's due to the characteristics of NPG+, which the sensor is reading from. The more telling indicator would be the metal temperature but since the OEM stock gauge doesn't give a numerical readout, I can only guess.

Don't do it if you're uncomfortable, it's just an option to think about.

 

If you don't have cooling issues, stick with what works (EG/water). I'm not trying to sell everyone on Evans NPG+. IMO, Evans is worth trying with FMIC, and hard open track driving. EG/water didn't work for me at open track, but the EG/water mix was fine for road cruising.

 

Where did you get a low pressure cap for the AST? Can I just use the stock filler neck cap for both the AST (Pettit can) and filler neck? Evans tech person said I can use my 15 psi pressure caps (which I have installed on the filler neck).

 

I have an aftermarket AST that uses standard size rad cap. The cap is a 7 psi cap.

 

pomanferrari - all those engines that had coolant failure where they Mazda remans? Where did you have them built at? Did they replace all the irons?