since I haven't seen a nice post about cam gear gains for our cars I'll make one. First, we know the 2.4L turbo Eclipse aftermarket cam gear fits our 2.4L mivec engine with slight modifications to the cam gear. Secondly, we have to test an advance of two degrees at least. I believe if you advance it after 4 degrees you lose hp, and if you leave it at 0 you'll still lose hp. Now my question is, since I have RRM's piggy I'll obviously have to tune it because of the degree change, if I tune it properly, how much gain will I expect?

I'd also like to know if people here have done this and what gains did you find?

 

With just a piggy-back as your mods, I dont think you'll see very high gains. Most gains using cam gear tuning are made by performance mods (I/H/E). The more aggressive the setup you have, the more gains you will see while cam tuning.

 

ya i dont see u geting mutch gain

 

2.4 turbo? U mean the 4G64 2.4 n/a right?

Theres cross reference between 4G69 and x64 camgears, b ut I guess very few people have tried it.

I would try it if I can get my hands on one

 

i have the rpw cam gear installed just havent gotten it tuned yet. had way to much going on at work, but i hope to get it done soon and ill let everyone know how it goes

 

you guys need to understang you wont 'gain' anything.. you will just shift the powerbang to lower rpm's or higher....when you retard the cam timing it will shift the power band for top end power, and when you advance the cam timing it will shift for low end power... depending on engine setup this may vary...

 

...and if you leave it at 0*, you won't gain or lose anything. 0* is just like leaving it stock.

 

If 0* is stock, what is the measurement at TDC? In other words, how far can I advance timing without going too close to TDC? I am assuming that stock (0*) is retarded so the plug fires after TDC.

 

I mean 0* on the adjustable cam gear, which would be like having the stock gear on.

Stock ignition timing when read with their scan tool is 5* +/- 3* BTDC. So anywhere from 8* to 2* BTDC. Now if you advance the cam gear more, say 3*, you should see your ignition timing in the 11* to 5* BTDC range. The more you advance it, the further from TDC you get.

Yes, retarded timing is when the spark fires after TDC. The only thing I'm familiar with that calls for setting the timing ATDC is my GF's VW bus. It makes for a smooth idle and cool running, but doesn't make much power. Her bus makes 60hp on a good day.

 

forgive me, what is B and A? Before and After? If so, why is our ignition set to fire before TDC? My understanding of this that would make the engine work against itself

 

With the engine going at all fast, the gasoline does not burn instantly. Contrary to what people believe, the gas does not "explode", it burns. It burns VERY quickly, but it's not an instantaneous explosion. The combustion will be pushing hardest on the piston some time after TDC, where you want it.
If you wait until TDC or later to spark, the combustion doesn't put the most force possible on the piston, and you waste power (and gas that could have done more work.)
In other words, at higher RPM, there is a delay between ignition and full combustion pressure. At higher RPM, this delay is significant.

If you could slow down the engine to like, 10RPM, you would probably wait until TDC or even significantly after it, since the delay between ignition and full pressure is insignificant.

 

If you retard your timing (for higher end power) wouldnt this show as more power on a dyno?