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Discussion Starter · #1 ·
Could someone tell me the positive and negative effects of advancing your timing. You do have to run a higher octane right?
 

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Discussion Starter · #2 ·
Noone knows huh????
 

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I thought it was already at 15 degrees?????
 

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On the B15 it is set at 15, B14 and under it is at 13 I think.
And as for the pros and cons:
from what i know, pros are that you gain a few hp and imporved throttle response.
Cons are the higher price paid for high octane gas.

You can learn more than you want to know over at se-r.net. Check it out. later
 

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Discussion Starter · #7 ·
You know I don't find any of those sites useful. Especially not for the b15. The search engine hasn't even worked on se-r.net for how long now? If anyone can find something on there, you must have a gift I don't. From what I hear SE-R.net is useful but I seriously have never been able to use there search engine. Do they have public forums????
 

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Can you just advance it when you go to the tracks and then put it back to normal after?... I'm not gunna do that, but i just wanted to know the effects that will have on the car.
 

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Enemigo said:
Can you just advance it when you go to the tracks and then put it back to normal after?... I'm not gunna do that, but i just wanted to know the effects that will have on the car.
I'm sure it will have some kind of long term effect on your car....
 

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aslong as you keep your car tunned and dont try takin on the rockie mountains in fifth gear you wont have any problem you get a better "pull" and throttle response....it is reversible it you want to ...only takes like fifteen minutes to do.....its free hp!
 

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Ok...what timing does is change the times where the intake and exhaust valves open during the compression stroke (when the piston moves up and down in the cylinder).

So basically, the intake valves open, air comes in, the fuel injector sprays some gas into the cylinder, the piston compresses the air/gas mixture, the spark plug fires, then the exhaust valves open so the burnt off gases can escape. The combustion is what kinda forces the piston back up, which turns your crankshaft. On our 4 cylinder cars, 2 cylinders are always opposite each other so that the pistons can be in constant motion.

Now when you change your timing, you're changing the overlap time of when the intake and exhaust valves open and also when during this overlap the spark plugs fire.

If the exhaust valves open at the same time as the intake valves, our cars will get almost no power cuz of no compression. (I think this would be a timing of zero). With a 15 degree timing, the exhaust valves open 15 degrees after the intake valves open so that there will be some time for combustion to take place and some of the force from the explosion can be transferred to the piston. With more of a gap between the opening of the exhaust valves and intake valves, more of the energy is transferred to the piston. So a timing of 20 degrees would give 5 degrees more time for pressure to be put on the piston...therefore, more power.

Now the downside of the increased timing is that there is also more heat that gets trapped in the cylinder head for a longer time. Also, too much stress on the pistons, rods and retainers can damage the engine. You also don't want to increase the timing so much that you interfere with the downstroke of the other pistons in the other cylinders.

This is why when you increase timing, higher octane fuel is needed. Higher octane fuel is actually LESS combustible than lower octane fuel. BUT we WANT less combustible fuel for higher compression engines cuz we want a more CONTROLLED combustion.

If you bump up your timing about 3-4 degrees and change to premium fuel, your car will be fine. The only reason that manufacturers keep the timing kinda low is cuz they know that people don't want to be forced to buy premium fuel. For enthusiasts who don't mind spending the extra money for the extra hp, bump up your timing.

It would be nice if someone out there could make an adjustable cam gear for our cars, but if you have a timing light and know how to use it, you can change your timing just at the track.

Sorry that was kinda long but it's a complicated topic and I wanted to fully explain it.

Note: I read this in Sport Compact Car and Car and Driver a while back so there may be some errors in minor details but the general concept is correct.
 
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