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RX8 not as fast as it should be

Old 08-12-2018, 01:56 PM
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RX8 not as fast as it should be

I recently purchased an 05 with 26k miles. The car is in excellent condition.

For the heck of it I test drove another 8 with 39k miles and noticed it was faster and the engine roar was louder. It did 0 to 60 in 6 to 7 seconds. Mine takes about 7 to 8 seconds. Kris (furansu) looked at my car and said it was in great shape and said the engine seems to be running really well. He pointed out 3 seperate (I believe he referred to them as actuators) that open up at certain rpms and said they sometimes stick which can affect performance. He will also do a compression test next time I take it to him as well ​even though it seems to be running flawlessly.

Here is my question, beside the things mentioned, what else could possibly cause a lack of performance. Supposedly the air filter was inspected by Mazda 700 miles ago as per documentation from the previous owner. Kris met me at a parking lot to do a preliminary inspection and will do an in depth look at it next time we meet. Kris really knows his stuff and fixed 3 issues right there in the parking lot. He is installing a new engine in his 8 and has a 7 as well plus a previous 7.

That being said, I just wanted to give the knowledgeable members the opportunity to throw in any ideas you might have that could cause this lack of performance beside what has been mentioned.

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Old 08-12-2018, 02:17 PM
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Louder engine roar could be as simple as an aftermarket intake. It sounds faster, but adds no significant power.

Were both cars you drove manual?
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Old 08-12-2018, 03:13 PM
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Have you ended up replacing your ignition components yet? Old ignition components are known to degrade performance.
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Old 08-12-2018, 06:40 PM
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Pull the air filter out and drive it around the block without it. That will be a simple test as to whether your filter is robbing you of performance.
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Old 08-12-2018, 08:04 PM
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Thanks guys
Loki, yes they were both manuals. Initially I thought because the other car was louder, it might have given me the perception it was more powerful. So I went back and test drove it again and did several 0 to 60 runs and it was definitely faster.

JinX, that is what I am planning on doing as soon as Kris is available again.

RX, sounds like a good idea.
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Old 08-13-2018, 06:45 AM
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Replacing the coils, plugs, and wires is the first thing you should do. The air filter would have to be extremely clogged to rob performance. I've seen engines run well and later learned that the filter was pretty scummy. Sticking auxiliary port tumblers would be my first guess. Carbon builds up in them and they are unable to move and turn freely. If they are in fact completely stuck, you'd more than likely see a code as the actuator would not be able to turn the auxiliary tumblers to a fully open position. Is the catalytic converter original?
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Old 08-13-2018, 12:05 PM
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As far as I know, the cat is original. The engine runs particularly smooth and quiet compared to others I've driven. Even Kris noted that as well when he looked at it. The engine compartment is very clean. Kris noted he didn't see anything that normally can get corroded or gunked up. I do know both previous owners kept it garaged and at 26k miles, it is as close to new as possible for an 05.
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Old 08-13-2018, 01:27 PM
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Things like aftermarket wheels, flywheels, trim levels (different weights), or even fuel in the tank can make a car feel faster or slower. Additionally, driver mod can be a huge factor depending who was driving.

thats said however, crummy ignition will have a huge affect, and if he was running high flow cat or catless, or had aftermarket wheels lighter than stock, or anything that affects rotational mass or power production will be enough to cause what you are experiencing.

our cars put out less than 200whp typically, so it is very uncommon for just 10whp to be a noticable and even measurable difference on these cars esprcially weight being factored in.
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Old 08-13-2018, 02:13 PM
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"RX8 not as fast as it should be"

said everyone ever since it first came out in 2002/3
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