My Rx-8's cooling system VS Rx-7's. LOL
 

Tell me this isn't funny. My first big trip in my 8, I went to reno. On my way back there is a 40 mile descent. Going up and down the hills that will last up to 5 or 6 miles each. anyway, I have done with many, many times with my FD and my old 99 Miata. With My FD during the summer I have to turn my heater on to keep the damn thing from overheating.
My Rx-8 has no such problem. No folks, no overheating issues.

With my Rx8 I have to turn the damn heat OFF during deceleration cause the gauge needle drops all the way to the left after doing down a hill. when I start to climb a hill again, my 8 warms back up and goes back to the middle.

Anyway, I thought this was funny as hell. Turn on the heat in the summer if you have an FD and turn off the heat during the winter if you have an FE!! Go Mazda!!! Oh yea, these are extreme conditions climing and droping elevation for miles at a time like I said.

Oh yea and my miata? the needle never moved, but either did the car.

If your needle in your 8 is moving around, something is wrong with your thermostat. Unless the 8 is set up in some strange way, your temp shouldn't drop like that. I mean, just idling in your driveway, it should maintain a certain operating temp.

in my driveway or driving around (I put about 450 miles per week) no problems at all.

It was just in the mountains when descending for 5 or 6 miles the engine got too cold. after I got into sacramento it went back to normal.

I dont know, I just think its funny. if it ever happens around here I would be worried.

I have never had to turn my heat on in the summer.. and never had any cooling issues at all with my FD.

well I should explain, I turn my heat on in my FD when the water temps hit 105 on the power FC, I guess thats a bit extreme. Climbing high elevation in 100 degree weather could cause the water temps to hit 110+. but in fairness I never had my guage on my FD move other than the times when my hoses/ast/fans/etc broke.

If the needle goes all the way to the left, I agree, something is wrong. Car makers have a "normal operating range" for coolant temperatures. The 8 is a water cooled engine, so there shouldn't be a rapid temperature drop coming down the hill. A small aircooled airplane engine is very quick to change temperatures on a rapid descent, especially after a full power climb, to the point where you can cause thermal shock to the cylinders. This isn't the case with cars though. The mass of metal in the engine and roughly 2 gallons of coolant would not allow such a large delta T on a gradual descent like yours. The engine is still producing heat while driving downhill also. It would be interesting to see if other owners have the same issues.....

Wanna race?

I'll ask the dealer, but it wasn't exactly rapid. It may have been 20 minutes of coasting down the hill for the gauge to move all the way to the left. and it wasn't completley, it was maybe 3 ticks from the end.

It doesn't sound normal, but its a mazda rotary so it probably is.

Sure i'll race your infinity G35 coupe. I'll bring my Rx7 you bring your title, deal?

I don't have a G35 anymore. I'll bring my RX7 you bring your "easy to keep cool" RX8

wait so are you selling your car or what zero?

Says so in his signature.

nah, I'm keeping my FD today Check back tomorrow, I keep changing my mind. LOL

i don't think there is anything wrong with that...if your traveling down a hill for 6 miles or so, you never touch the throttle, you only ride the brake...so it seems to me it would be like idling your car with 60 mile an hour winds blowing through your radiator...wouldn't that cool the coolant down a bit?

I read somewhere that the cooling system of the Rx-8 is based on a motor controlled system. i.e. no belts o anything. Is this true?

Because I like the idea. Belt efficiency is often lower than motor efficiency. Plus, you get a much more rev-independent control of the radiator pump. :)

Let us know what it does after you add a couple of turbos... :p:

FWIW, I've never had any heat issues with my FD as well... and I still have the stock AST!

|aFk| LiMiTz: Who's the cutie in your sig? Wow!

I never have cooling issues either on the street.
Take it to the track and in hot weather your eyes better be on that temp gauge ;)

This also happened to me in my FD with stock cooling system. It was winter around here (Seattle) and I had my heat on high and fast speed setting. When going down a 1 mile hill, just coasting in neutral, the temp gauge slowly began to move to the cold side.

That shouldn't happen. Doesn't matter if you are idling and lots of cool air going through the radiator. The temp is taken from the engine side of the thermostat. If it starts getting cool, the thermostat should close, and the engine at idle should produce more than enough heat to keep the temp up to normal. Sure the water in teh radiator is super cool, but that isn't being used or metered.

:werd:

...and this spring will be 11 years in my custody. I've driven in 110F temperatures in Tucson, up and down Vail Pass, CO in 80F temps at 11,000 feet at well over 100 mph. Never a problem.

(Well, except for the stock radiator which leaked...)

RX-8 also doesn't have a turbo. How long does it take to warm up the 8 and your 7?

I think this says more about the difference between the FD's water temp gauge and the 8's.

your comparing a N/A rotary engine to a turboed rotary engine. Yes i know, good call sherlock, point being the turboed rotary will run hotter no matter what chassis. Bolt a turbo kit to that sega genesis renesis and see what happens.
Why did you dump your 7 for a Rx8??:confused:

Im not hating on rx8's but when i first saw one on the road cruising on the highway.(silver) As i saw it pull on the highway i thought, god damn that is the ugliest bodykit ive seen for a hyundai tiberon. So i paid no attention to it as i passed, then i saw the HID's. So then im thinking, those POS's dont come with HID's so i slowed down and was like,, Oh F---! thats a rx8. IMO i dont like their styling, but thats just me. Everyone has an opinion just like everyone has an asshole.:D

Edit: what do you have now a 7 and an 8? :confused:

Actually, while the renesis will run more hot with a turbo, I would highly doubt it will have any cooling issues. For 1 the radiator is very big, 2 the opening under the car is simply sick, and lastly its sealed very well. My money says there will bo need to upgrade the cooling system when a turbo gets installed. The rx-8 in general is far better engineered than the FD.

I didn't, I have both cars.

I happen to very much like how they look. they have an animated look, a ton of character and are probably the coolest looking car on the road.

Yes I have a 7 and an 8.

Remind us again which one has a turbo ?? :rolleyes:

I dont get it. I didn't even post this about the FD overheating, I posted this because the Rx-8 appears to "Under heat". I found it amusing considering the FD's rep.

Hey Zero... I thought your FD didn't have cooling problems after you took the front plate off :rolleyes:



Sounds like to me your RX8 and FD have problems.



Or your just making up some lame story.

What is your problem with me? Why must you attack me?

why would I make this story up? And this has nothing to with my license plate. I have never overheated my Rx-7 since I replaced the radiator fans (2 times), AST (1 time), overflow tank (1 time), Throttle body hose (2 times), Upper radiator hose (1 time).

The FD's water temps rise like the nasdaq in 1999 on a hot day when I climb a hill. As I said earlier although my water temps in my FD (and this is like last summer) when Im going to reno rise very high (105+) so I turn my heater on. yes I may be going to extreme but its an FD, if something can go wrong it will.

please refrain from attacking me.

zero has a very nice fd.

If i am correct I thought the 8s were blowing up within 1500 miles due to a coolant seal failure. Not trying to be an ass but I dont think the renesis is that much of a great advancement in the rotary world. We are still yet to see someone put a lot of miles on a turboed 8 to see how the seals will hold up.

no they haven't been blowing up within 1500 miles (I have 1550, lol). There have been a handfull that have had coolant seals leak and got a new engine. The last I heard out of nearly 15,000 US cars sold, 80 had replaced engines. While I agree that number is much higher than it should be, the theory is the problem is with the assembly of the engine and in the scheme of things its insignificant (unless its your engine).

The engine is so superior to the 13B and 13B-REW. Its meets emissions, makes way more hp, gets better gas mileage (I drive both, I know) has a higher redline, weighs less, is smoother and quite frankly.....Better.

Like any other form of bad news about something on the internet, I'd wager a guess that the problems with the RX-8 occur with far less frequency than we may have been led to believe.

All ZeroBanger said was that when ascending and descending freaking mountains that temps in both of his cars fluctuate and noted the differences. Many of you seem convinced there's some kind of problem or that he's an idiot and I don't get it.

Speaking of hp what is the final # mazda released for the 8s. I know they changed it quite a few times and is it the reason for the buy back option? Not to familiar with the N/A 13bs but I thought they were around 180 hp. So I was just wondering how much more power the renesis had and was the weight of the 13b-rew with the turbos or without. Not trying to argue just trying to learn the differences. Also compare ride quality of the two if you dont mind.

180rwhp? that's weak.

Insane Gideo...my sig is kristen kreuk, she is my soon to be wife.....jk... http://home.earthlink.net/~ac90/sodamncute.gif
hottie

I believe the final US figure is 238hp, I don't know if that's to the rear wheels.

It was, on release, announced as 247hp. I'm not sure if this was to keep the claim that the Renisis meets future emmissions requirements (for 2006, and I don't recall which standard that was).

Although the Renesis is good engineering, it only equals its peers accomplishments.

It by no means competes with some of the latest German big blocks; some with better gas mileage (than the Renesis), and a ULEV certification. I realize it isn't fair to compare the Renesis with these $70k+ vehicles, but it seems some of the RX-8 advocates would like to put it's powertrain on a pedestal with them.

I like it! The RX-8 is a practical sports car and well suited for the current market. It is not in the same segment as the FD3S RX-7, which is a super-car. It is in a segment more like the original RX-7, the rogue.

The RX-8 is great engineering for the time, so were our awe-inspiring FD's.

-C

The n/a 13B was 160 HP at its peak. This engine is 247 HP (Japanese version). The us version was also going to be 247 but they could not meet a new regulation that required the cats to live 100,000 miles. They reduced the power to reduce the heat to meet that requirement in the US.

You cant dyno an rx-8 because its ECU will cut the power to the wheels (even with traction control off). This is not an issue in racing the car, just on the dyno.

The weight of the 13Brew with the turbos was some 390 lbs. I dont have the exact numbers with me, but the engine itself is 30 pct lighter than the 13B-rew and is smaller (12 inches high) actually the same hight as the transmission.

There is no comparison to the ride quality of the FD vs the RX-8. The FD is very harsh and is put together like crap. Its cheap plastic that just breaks, squeeks, rattles and squeels. You hit a bump or a pothole and as you know it just jars you. The rx-8 has a very, very refind feel and is quick. It soaks up pot holes and un-even surfaces. The really cool thing is that the car gives you feed back from the road. You know you hit a bump, but it doesn't transmit to the chassis or your body.

Having said all of that the FD has much higher limits in most catagories. While the steering, chassis and stabililty during braking is fars superior in the rx-8, grip, overall handling and power are far superior in the rx-7. The rx-8 gives you a very smooth ride but isn't quite as neutral as the FD. You feel SLIGHT body roll during a turn, but its very very minor. Interms of fun, both cars are equally fun, but on the street the rx-8 is superior. It gives you a level of confidence that the FD doesn't. It offers 95 pct of the handling of the FD without the punishing ride. Take the FD around a corner at 75 MPH and hit a pothole or a bump in the road. Then do the same with the Rx-8. It grips so hard and you feel like you can keep pushing it harder and harder.

If you remember just prior to production mazda showed an rx-8 and an rx-8 in the twisties. During the turns the rx-8 easily caught up to the rx-7. During the straigts the rx-7 easily put distance on the rx-8, but again as soon as the turns came the rx8 gained ground again. I was very skeptical about this when I first saw it. But after driving them both hard I understand it. An average driver in the rx-8 would beat an average driver in the FD in the "twisties". A very good driver in the FD will easily beat one in the rx-8. Watch the top gear video it describes alot of this to you.

http://homepage.ntlworld.com/andy.wray/topgear.wmv

why are all you guys being so critical of zero's story.... thats the only lame part of this thread......

It sounds like Mazda may have over engineered the Renesis' cooling system to make up for the FD's faults.

The temps should not not drop when coasting. As stated before, the temp is measured at the engine and if the thermostat is closed, the engine should easily be able to maintain that temp, even in below-freezing temps. However, I wouldn't worry to much about it.

I personally did not like the RX-8's styling at first but it has grown on me. It's definitely not in the same league as the FD, but not bad for the cars that have been coming out lately.

Also, Zerobanger, you initially called it an FE. Is it really considered the fourth-generation of RX-7s? I don't consider it in the same class and it doesn't even carry the name.

the sig "FB", "FC","FD" and "FE" are all chassis codes. you can find the letters in the VIN. I'm not saying the rx-8 is or is not a replacement for the rx-7, but its definately the FE.

Remember, the RX series has had all different types of cars, station wagons...even a truck? sedans, 2 seat sportscars and the what ever you consider it Rx-8. There may not even be a new rx-7. If there is I will sell my FD for it, not my Rx-8.

To start off, I will say I really like the RX-8. I'm building piggyback fuel controllers for it (Canzoomer's Stage 1). Lots of fun. Best engineered rotary car yet!

A few facts:
The water pump runs off the belt.
The power steering is electric (EPS) as is the air pump.
The RX-8 has the same temp gauge setup as the RX-7 - it's a go/no go readout.
The engine produces around 220 HP (we measure 180 to 210 HP at the wheels, depending on mods. - 180 in stock EPAII configuration). Not bad for a N/A rotary.
Most cars will get too cool going downhill on long mountain pass'. Both my RX-7 and my Pathfinder do.
My RX-7 gets better fuel economy than my friends RX-8 - both city driving and highway cruising. I found this kind of funny (he doesn't). My car probably runs about as lean as it can without det.
You can dyno your RX-8. Just remove the bolts for the rear ABS sensors, back onto the dyno, pull the sensors out and tape out of harms way. Do your dyno runs with DSC turned off (hold button 5 sec.), but keep the runs to less than 20 sec. per pull. Put the sensors back in before driving off the dyno, but put the bolts in after driving off the dyno (if you drop them into the dyno rollers you will have to leave the car there until you can get replacements).
I thought the 1st gen was not an FB (everyone here calls it that except Mazda). The RX-8 is an FE. IF the next RX-7 is built, it would probably be an FF. Suitable designation, I'd say (F'ing Fast!).

As for how fast the RX-8 is, my friend's car (he is known as Canzoomer) is now close to stock RX-7 territory. Handling is at least as good as an RX-7, maybe better. Yes, the power is down. Interior appointments are far and above the RX-7. Cup holders, comfortable rear seats. It has LEDs in the dash doing things for you before you even put in the key! The RX-8 is amazing with DSC and ABS. It's pretty hard to "get in over your head". The car will save you. There have been several posts by owners whose lives have been saved by that car. The RX-7 has the right combination of power and handling to get us in over our heads too often!

All I'm saying is if you take an FC T2 and an FC N.A. you'll find the N.A. has lower temps with the same Coolant mods... due to the fact that Turbo Chargeing creates heat, so what he's saying 1 Isn't news, and 2 he's not even close to comparing the same car, as I did with the FC....

David,

thank you for your post that was great. The only thing I would like to add, the 220 hp was a result of the last minute de-tuning that mazda did. Otherwise the engine definately makes more. Probably makes closer to 240 flywheel.

And about the gas mileage. My 94 rx7 has about 350 rwhp and is ported, etc. In the beginning I found that I was getting better gas mileage in the FD. It took awhile to realize but in general I am at lower RPM in the FD, and I believe that is why.

during my trip to reno I did some tests. I have taken my FD many times on the same trip. On the way back during several 95 mile stretches I put on the cruise control at various RPM's to see my gas mileage in the rx-8 and compared to my 94 Rx7. I would get 25 MPG in my FD with the cruise control on at 3000 RPM on the highway. In my Rx-8 I got 30.22 under the same conditions, same road. I was very shocked by that number, but its what I got.

Keep in mind, I was at 3000 RPM 6th gear. That translates to about 60 MPH vs 80 in the FD.

During my normal driving to work keeping a steady foot on the gas, I take highway and some city mixed, I get about 18-19 in the FD, my Rx-8 gets 20-21.

When I push the FD hard I almost never get less than 16 MPG, 17 is normal. With my Rx-8 its comparable. I need to do some more testing with 91 octain to see my gas mileage when I am abusing the 8 in comparison to the FD.

I dont think you understand why I made this thread. I thought it was funny that my rx-8 almost "Underheats" while the FD almost "overheats". turning the heat on in the summer with the FD driving up a hill and turning the heat off in the Rx8 going down a hill during the winter has some humor, dont you think?

Thats all it is about. I'm sure driving down a mountain pass in 30 degee weather the FC's needle doesn't go almost completely to the left side, does it?

This has got to be the most pathetic forum in the world.... David has been the only one with useful info everyone else has flamed zero for telling a story that did not put the FD on a pedestal, get over it, knock that chip off all of your shoulders... if the FD was the greatest car ever produced they would not need the amount of maintenance and TLC that they require to keep them running well.... If you guys had wanted reliability you would have done what i did and got rid of the rotary and put a NISSAN engine in... why can't you guys just except that the RX8 is what most budget sports car are heading towards---> less power more reliabilty and 4 seats...... Good Luck zerobanger enjoy both cars don't pay attention to all these idiots....

Shaun

i would also assume its cold around reno, thats prolly 90% of the problem.