hey i jsut got my true duals for my 91 n/a, and there are two stickers/tags in there that said "warning use octane 92 or higher only" should i use 92 or higher only or jsut stick with my regular gas octane, 87.

thanks
eric

 

Ask Mazdatrix for an explanation.

 

hahahah wtf are they talking about?

I have run 87 since I got them a year ago and nothing wrong has happened. :-/

Santiago

PS e-mail MT and ask why they recommend taht **** now.

 

I'm curious too.. They are on my '91 N/A also, nothing has gone wrong with mine either.

 

hey that's funny stuff considering mazdatrix is in SoCal and the best gas we have here is 91 octane . maybe they wan't you to shoot more flame flame

 

Cheapest stuff possiable is what I run. CJ

 

It is NOT a now thing!

I got the same sticker when I purchased the Road header, pre silencer, HKS cat back

 

I think the premium gas thing is misleading. You dont have to run premium, but your timing may need to be adjusted. I had my timing advanced before my true dual(very long time ago), and when I put the true dual on, I had to take out some of the advance due to preignition. Apparently a more free flowing exhaust reduces the prignition threshold.

 

more scavenging = less burned gasses in the combustion chamber for the next cycle

mike

 

KD - what kinda dual did you get? How much? Got pics? Did you notice some good performance when you put em on? Hows it sound?

Sorry for all the questions, im interested in moving to true dual myself. I have a 91 vert n/a.

 

I have the ones with RB mufflers. Search for Rarestrx he also has them and hat a write-up on them. With some very nice pics of them on the car from under it. The performance of True duals is very noticable.

 

Sweet!

Bing!

That looks like a sweet *** exhaust. $1300 though. hmm.... Tax Return.

 

Yes they are very sweet. If you search for my thread where I met up with other peeps from around here namely MAX and Wankel7 you will see some nice sound clips/vids and pics. Some people don't like the sound of the True Duals. But I love the sound. Specially after hearing other exhausts like the cork sport, N1's, etc.

Santiago

BTW- The price is the killing factor for them.

 

Yeah thats a little much for an exhaust system, considering I didn't pay that much for the entire car. Also I can't justify spending more on an exhaust system than it costs for a rebuild.

 

Yeah well I still haven't needed one so there.

 

 

How long you think that bad-boy will last?

 

I've always been confused on why to not run 93 in an n/a, I've ran it for the past year, and my car runs smoother and quicker than before, please explain

 

mazdatrix emailed me back saying..."ignore the tag--looks like we forgot to take it out"

 

It has a higher detonation/combustion rating.

I think(might be wrong) that the lower the number means that it burns quicker while higher octanes burn slower.
Correct me if I'm wrong since I'm guessing.

I ran mid grade in my GTU but didn't notice a thing so Now I'm using the lowest (87 i think) and it's running the same.

 

The car seems to run smoother on 93 octane, but it takes longer to burn. Only a small part of the power stroke is truly efficient. Think about the expanding gasses. You have gas under pressure, but as it expands, the pressure decreases. As the pressure decreases, so does the force exerted by the gas. At low rpm's, this isnt a problem when you have the timing advanced. The mixture still has time to burn within thew window of efficiency in the power stroke. But as rpm's climb, that time is reduced, but the gas doesnt burn any slower. So youre losing more and more of the force during the efficient part of the power stroke as the rpm's climb.

Now, this isnt a difference of 20 rwhp. Nowhere near that drastic. But the reasons for 93 octane are that it is less volatile, which makes it mroe resistant to knock. BUT, the volatility of gas in general is what makes power, and within the safe limits of the motor, a lower octane will always make more power. This does NOT account for timing, as this alters the safe limits of the motor, as does boost. Another thing, you will get better gas mileage with lower octane. Back to the volatility thing. The gas burns faster, therefore more of its energy is used in the efficient part of the power stroke. This requires less fuel to make the same power. If the power stays constant(say cruising), less gas will be used.

Octane can hide other problems. For the longest time, I could not run 87 octane. No matter how much i retarded the timing, it just would not run as good on 87 octane as with 89 or 93. Come to find out, my intake temps were too high(cone filter in the engine bay, no cold air box), and later, my plugs were too hot. Now that that stuff has been taken care of, my car runs like a champ on 87. And the money I save on gas can be put to better use.

 

The octane rating has nothing to do with burning/flame speed. It's just a gauge for resisting preignition/detonation. Some require high octane since they will det/ping with the low stuff.

 

There is nothing wrong with running high octane in an NA other than it's a waste of money for most people. If your engine is in extremely poor shape and detonating, or if your engine is highly modified with advanced timing, then high octane will make the engine run better. Otherwise, high octane will do nothing for you, as it does not run any cleaner, it is not any more powerful, and it doesn't have any other magical properties, despite what the money-grubbing oil companies want you to think.

Read the FTC's response to the misleading advertising of high-octane fuel:
http://www.ftc.gov/bcp/conline/pubs/autos/octane.htm

It's interesting that when it comes down to official statements, the oil companies come clean on the issue:
http://www.chevron.com/prodserv/fuel...i_octane.shtml

You know how all of the oil company advertisements always say that their most expensive gas has their "special sauce" additives? Well, what they usually fail to mention is that ALL their grades of pump gas also have it, lol.
Hey look, Techron is in all 3 fuel grades!
http://www.chevron.com/prodserv/fuel...tech_gas.shtml
Hey, so is CleanSystem3!
http://www.texaco.com/texaco/prodsvc...tm#cleansystem
Hey, all of the Shell grades have their special super-secret additive too!
http://www.shellus.com/products/prod...oline_faq.html

Hmm, I'm sensing a trend here.

Therefore, if the ONLY advantage of high-octane pump gas is it's anti-knock properties, and your engine doesn't have a knocking problem, then what are you paying for?