Edenney

I tried searching for an answer to this question, but despite search criteria specifically related to power gain at high rpms, all the results I find are related to power LOSS at high rpms.

My question is, in a stock 2005 RX-8 (automatic), is it normal for there to be a huge power boost around 6000 RPMs give or take? I've never driven another rx-8, so I don't know what "normal" is for that car, but it's always seemed to be under powered from a dead stop and at low (1-3K) RPMs, but takes off like a rocket as if a turbo kicks in when it gets up around 5-6000RPMs. It runs fine but it's always idled rather rough, despite replacing several things over the last several years that other members on the site have said were common fixes for rough idle problems. May be zero connection between the rough idling, the low-rpm lack of power, and high-rpm huge power gain, but I just wanted to throw it out there in case it might be relevant. Thanks in advance for any constructive input.

RX8Soldier

iTrader: (24)

Well, it all depends on your description of "a huge gain"...

Could be:
1. It's not a boost. You're just experiencing an untuned "butt - dyno.
2. Your ignition or exhaust is in poor condition.
3. A component of you VFAD is malfunctioning.
4. You have a turbo and you didn't know.

Could be other issues, but your description is lacking some info...

Edenney

Thanks for the reply. If you could request specific info that I can reasonably obtain, I'll try and give it to you.... It's not my car, it's my mom's, so I don't know everything about it by heart. Bought it 2 years old with very low mileage in 2007 for my mom to drive, so she's had it for several years and I drive it every once in a while.

It's definitely not a turbo (no turbo sound, no boost gauge, no visible turbo under the hood, and nothing in or on it anywhere that says turbo, and it's stock). When I say a huge boost, I mean compared with the power it has in the low to mid rpm range, it literally feels almost like a turbo kicking in around 5-6K. It's always been very weak at the bottom end though as I said, like a pretty weak economy car. Probably isn't much on the road that wouldn't beat it 0 to 40, but it flies along on the highway and has lots of power in the upper rpm range. Plugs and wires have been replaced at least once since purchasing. Did the Catalytic Converter 4 or 5 years ago. Car is only driven about 8Kmi a year. Had one of the solenoids changed out today (p0661 errors for a few months), apparently a fairly common problem with them. Can't speak to anything else about the ignition or exhaust system, and I honestly don't know even know what the VFAD is (vacuum related?), but I'll look it up after this reply.

BigBadChris

iTrader: (4)

The RX8 is notorious for a lack of power in the low RPM range. I think youre looking at this all backwards, my friend. Its a lack of power everywhere else. Once its in the power band, youre off to the races.

wankelbolt

iTrader: (21)

Edenney, add your general location to your profile, there may be other RX-8 owners near you who you could compare to. It's likely there's nothing wrong, it's just the nature of the automatic RX-8.

BigBadChris, Every time I hear that "lack of power" line I like to follow up with "Yeah, those crap LS engines are notorious for having no power over 6000 RPM."

Striker-7

iTrader: (3)

As a RX-8 owner, and a LS2 (LH6) driver, I'll chime in here.

Anyone who has driven a Wankel for any length of time knows why it is called the 'torqueless wonder'; very little "oomph" below 5 grand RPM, but rev it above that, and hang on while it sings to redline and beyond. The inherent nature of the rotary is that of a 2-stroke piston engine, it needs to spin fast to make power. Contrast that to the LS motor (thanks a lot there, 'Bolt!), which makes power virtually off idle to about 4500, then trails off to 6K, where the ECU shows it mercy and limits it from thrashing to death. Honestly, the upper range of the tach in my truck should be labeled, "What's the point?".

My dear sister, who among other things used to drive long-haul trucks, observed that driving a rotary well was akin to the thrashing she had to give a Detroit Diesel; "You have to rev it like you hate it!". The simile is apt; the Detroit was a 2-stroke diesel, it needed high revs to generate torque, and was really potent at the upper limit of the RPM range.

TL;DR: Rotaries are simple, ya gotta spin it to win it.

logalinipoo

Right in line witheverybody else. They develop power better at high rpm. Look into the manuals that Rev to 9k and have quite a bit more power.

Also if it's a6 port auto. You might be feeling the last 2 ports opening. That gives a nice Lil kick.

ouimetnick

The 2005 & 2005 RX-8 automatic uses the 4 port engine, and also lacks the VFAD, so no 2 extra ports opening, and no malfunctioning VFAD.

logalinipoo

Thanks for the note, 6speed here so I've never really paid attention, but I think he meant SSV. The VFAD wouldn't cause much trouble if it was malfunctioning anyway.

reni04

The rough idle is a little bit in my 2004 rx8 automatic. The only way i know of to fix that rough idle is to get a cobb/passport tuner and change the fuel idle settngs in the ECU. The turbo effect is in all rx8 . The rotory renisis is basically a turbo design it self. My 8 does that about 4500 rpm all the way to the fuel shut off bell/rev limiter. I ring that daily every time i drive it. 100,000 plus miles only things replaced so far are coil pacs/plugs/plug wires.