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Location: Birmingham, AL ... before Cincinnati, OH
Thinking about buying an 8...
I'm finally thinking about replacing my daily Acura and thinking about buying an 8... This time, pretty serious about getting one.
Since I'm pretty new to the 8 (not to rotaries) I need some pointers.
1. I have a Mazda compression tester and wanted to know how to hook it up to an 8. I don't know much about where all the fuses are and some direction on how to measure compression.. and what the compression reading I should be looking for in an 8 (I'm guessing similar to other rotaries?).
2. What are some common problems with 8s? Ie, is there certain parts that breaks often than other or that should of been replaced? Anything I should look for??
Any info would be greatly appreciate it!
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I can't so I'm going to pretend to. however these cars are not the deadaches the FD's are. As you probably know the vacuum system in that car is ridiculous and if you are not careful with actually tuning for your new mods you can pop and engine pretty easily and the factory PSI was pretty difficult to actually ever see. Throw in the abomination of a cooling system that car had from the factory and the car is...as you say....a headache.
The 8 on the other hand is naturally aspirated and has an adaptive ecu so you are not going to blow a motor by opening up the exhaust.
Life is tough. It's tougher if you're stupid
Oh he can drive. He can drive beyond the limits of the tires, the engine, the car or anything else.
You run the comp test on the 8 the same as you do the FD and other rotaries. You can use the leadings OR the trailings...most use the trailings. Remember the renesis sits about 4 inches further down, and 6 inches further back, than the FD engine...so they are considerably harder to get to, but it can be done.
The rx8 FSM actually gives instructions for the comp. test. Mazda appears to have revised their expected/acceptable compression readings from ~85psi to ~95psi. Since 95 is roughly the threshold of consistent flooding/hotstart issues and poor idle, they finally acknowledged what we have known for years, that an engine with 95 or below is getting too weak to use reliably.
Issues with 8's include weak ignition/coils, expensive sparkplugs, clogged stock cats at low mileage (my cat was totally destroyed with 111k on it), squealing brakes, and motor mounts that cause vibration at idle. And of course a theorized lean OMP injection ratio that causes the need for replacement engines...so just run about 4-8oz premix per tank once you get one.
however, according to my early research, you pretty much buy the rx-8 for what it is, not for what you want to make it (like an rx7). Sure, you can do an intake and exhaust and pick up 20rwhp at redline. There's not a lot else you can do for major hp, unless you want to spend a shitload of money on a small turbo and a computer to run it, and struggle to make 300rwhp while being on the edge of blowing the motor the whole time. There's little porting that can be done, and no options for changing compression ratio at this time. Also no options for changing apex seals to different materials, sizes or strengths due to inability to machine the rotors. And the renesis will be more expensive to rebuild/refresh once it actually blows apex seals, versus the older rotaries. OF course, I gather that you and your builder are "all new parts" guys anyway, so I guess that won't impact you much.
Last edited by RotaryResurrection; 07-18-2007 at 02:38 AM.
Location: Birmingham, AL ... before Cincinnati, OH
Kevin, Thanks for the great info... I totally forgot to ask you about your 8 when I saw your yesterday..
Razz1, My wallet is already broken by owning FDs.. And I don't consider 8 to be more of a sports car then the FD. If I were to buy the 8, I'm not spending any money on engine related performance mod and maybe upgrade the suspension and wheels (which wheels I've bought for my FDs will fit - SSR comps).
Well, I met couple of 8 owners at the Grand Am race this weekend and got some honest opinion about owning an 8.. I'm going to make another offer and if the seller doesn't take it, then I'm going to either find another or move on and buy something else..
There's a special way to test compression on the 8.
Uh, no, no there's not. At least, not compared to previous rotary compression test procedures. I did forget to mention an important part above...either unplug the crank angle sensor, or remove EGI fuse/relays to disable the fuel injection during the test.
Never turn the car off as it may or may not flood.
Yes, because it specifically says in the owners manual to leave the car idling, like a diesel at a truckstop, 24/7/365 so as to prevent flooding.
Your wallet will be broken. It's a sports car.
It is a sportscar but it's a fairly tame one, and they're not prone to breakage in stock form with a responsible driver. If you can afford the gas and oilchanges, plugs and tires, there should be no issues.
Phil, if you have any questions I can try to answer them for you, just shoot me a pm or email.
Sorry I did not get a chance to look at that link you sent me about the 8 you were looking at. In fact I think I deleted the pm after I replied without thinking...so resend it if you'd like.