Changing the timing

[evil_weevil]

I did search, but still couldnt find relative info for my liking, so thought I'd apologise first LOL

I have heard people of changing the timing on their mx5's for a little bit more power providing they run 98 octane with stock ECU and cams/cam gears etc

Now, questions on the timing...

what is the stock NA8 timing?
And what would be a safe level/number to change it to? (have really basic mods, exhaust and intake)

Is it important to change? worth while gains/benefits?

Cheers,
Chris

[Guran]

The stock timing for manual NA6 and NA8 cars (1989-1997) is 10 degrees BTDC. For max horsepower and regular shifting above 6500rpm, 14 degrees BTDC should liberate an extra 9bhp according to Garrett's book. You can set at 18 degrees BTDC for an extra 20% torque at 1000rpm (good if you shift below 5000rpm) but need 98RON for that. I find my car doesn't knock with 14 degrees BTDC and 91RON fuel. Even so I usually top up with 98RON before a track day, just to make sure. I definitely noticed the extra poke at Wakefield with an extra ~5km/hr at the end of the straight.

[evil_weevil]

Cheers Guran!

Another "silly question" - how do you know its knocking? And if it is, how do you know its minor or major?
I know with my R33 - I had the apexi powerFC that showed knock levels, so I could monitor the knock that way.

How hard is it to advance the the timing to 14 degrees?

Cheers,
Chris!

[kazjim]

"Another "silly question" - how do you know its knocking? And if it is, how do you know its minor or major?"

If you can hear a light tapping from the engine bay, then it is already 'knocking' or 'Pinging' pretty hard ...

the basic rule is that if you can hear it, then its major.

J

[evil_weevil]

Sweet,
Cheers kazjim!

Is it a different noise to say...a noisy lifter? (Got a mate with a very loud noisy lifter n his SR20 silvia )

[Fuzzlet]

Its similar but different. Advancing the timing aint hard, just a matter of using a timing light and adjusting the position of the CAS

[evil_weevil]

CAS...?

[Guran]

Crank angle sensor. It's located near the back of the cam cover. Adjusting the timing is a 5 minute job. If you're coming to the club track day on 21st June I can show you how to do it yourself. Easy peasy! All you need is a timing light, multimeter (optional), screwdriver, 12mm spanner and a paperclip (seriously!).

As for knocking, drive up a bit of a hill at low revs (say 3000rpm) and try to accelerate. If you hear something like a bag of marbles being rattled, that's knocking. Try it again with a tank of 95RON and it should go away. If not, step up to 98RON.

[evil_weevil]

Guran,
Cheers mate, your answers are awesome!!
Unfort I wont be able to make the track day due to work committments

but it does sound fairly easy, i'll have to give it a go sometime!

I always use 98 octane anyway, so thats no drama!

Iwas at OP GP today, no official timing, but was there with another club (SAU NSW - Im still the VP) and was keeping many skylines honest for the whole track apart from main straight!

So Ineed that extra HP!!!

[StanTheMan]

well to be honest with you.......I personally doubt you keep those skylines much more honest along those straights after the timing bump. But I do agree. The timing bump has to be done regardless. every killer wasp counts.

[evil_weevil]

Yeah the straight Ive got nothing, but as soon as Im at turn 2, so are they - then the back of North section and south parts of OP GP Im all over them and could take a few under brakes. But again, as soon as I got to the straight - vvvrrrooommmpsssccht! off they go, and same again, catch them at the turns and under brakes!

God its fun!!!!

Ok cool, My next sprint is in august now so time to get stuff organised