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Old 09-13-2010, 01:49 PM   #1
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Default engine knock

I've got an '03 VTT motor, which I think has a 10:1 compression ratio.

Could I still get detonation on this motor at 5 or 6 psi (non-intercooled base kit) in 11 to 12 in-boost-AFRs and stock timing on 93 octane gas?
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Old 09-13-2010, 01:59 PM   #2
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Umm. hell yes.

And its got 10.5:1 iirc
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Old 09-13-2010, 02:32 PM   #3
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Go 93 like you are doing, get the coldest plugs NGK-7 and a detonation device. Advance as much as you can until you hear engine knock. Check spark plugs when dialing ignition timing.


AFR and ignition readings are two different things.
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Old 09-13-2010, 02:42 PM   #4
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Quote:
Originally Posted by mazpr View Post
Go 93 like you are doing, get the coldest plugs NGK-7 and a detonation device. Advance as much as you can until you hear engine knock. Check spark plugs when dialing ignition timing.


AFR and ignition readings are two different things.
Most importantly, don't listen to ANYTHING this guy says about miata's.
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Old 09-13-2010, 03:05 PM   #5
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What would you suggest, 18psi?

So getting good AFRs alone isn't indicative of running your motor safely.

If the timing is too advanced (or still stock in the 10.5:1 motor), could you still ping even running rich?

Last edited by Scigano; 09-13-2010 at 03:16 PM.
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Old 09-13-2010, 03:11 PM   #6
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Quote:
Originally Posted by mazpr View Post
Go 93 like you are doing, get the coldest plugs NGK-7 and a detonation device. Advance as much as you can until you hear engine knock. Check spark plugs when dialing ignition timing.


AFR and ignition readings are two different things.
You're a total retard. Seriously, stfu. We jack with people on this forum but when someone asks for help don't yank their chain on something that could really hurt the car.
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Old 09-13-2010, 03:13 PM   #7
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What he said/\
Has nothing to do with elite or junior. He is giving you bad advice cause he knows literally next to nothing about miata's. You don't have to believe me though, frankly I don't give a **** if you listen to him.


What do I suggest?
Get proper engine management. Tune your car for optimal fueling and timing in and out of boost. Or get dyno tuned by someone that knows what they're doing. Win win win all around and not blow up your motor.

The 01+ has the highest cr of all na's/nb's. It also has vvt. The potential to make good power at relatively low boost is highest. The potential to blow up is also highest.
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Old 09-13-2010, 03:45 PM   #8
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Quote:
Originally Posted by 18psi View Post
What he said/\
Has nothing to do with elite or junior. He is giving you bad advice cause he knows literally next to nothing about miata's. You don't have to believe me though, frankly I don't give a **** if you listen to him.
fair enough, that was cheap - I worded that retarded.

So I shouldn't get those colder plugs? I'm in Orlando, I went to Central Florida Turbo to get my BEGI-S kit dyno tuned. I have a Voodoo Box, but I originally had a Jackson Racing Powecard from TDR.

I think one of the Potentiometers was **** b/c it kept trying to waterboard my engine right from tip in (AFR's as low as the 9's if I didn't give it the business!)

The Voodoo Box ran much nicer. Even when running rich on the Powercard, 10:1 to 11:1 under boost - with two degrees of retard (Keith Tanner's suggestion - but since returned to stock timing to clean up lowend), I'd get this light tick sound (like if something was rattling) sometimes.

On the dyno - CFT guys said they didn't hear any detonation (but that was in the garage - engine blazing, widows down, and they say you have to have the windows up and buttoned up to hear knock)

they rode on the street and thought they didn't hear knock either (but they're not Miata boosting specialist exclusively though).

Thank you, guys.
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Old 09-13-2010, 03:54 PM   #9
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How did they retard your timing? Voodoo box doesn't control timing
Often times 2 degrees retard is not enough, even at a measly 5psi.
If you hear pinging/rattling that is likely knock. If its at peak boost then its very likely knock.
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Old 09-13-2010, 05:02 PM   #10
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I also have a Flyin'Miata Timing Wheel.

I took it to CFT again and they think that the sounds coming more from the rear and that it's exhaust rattle in their opinion, they didn't think it was knock.

I've got another guy that's got an FMII disgusting Miata, so he knows a thing or two also.

I'll ask him to ride along as well and get his opinion.

(newb inexperience ftw )
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