stroker kit question.(tuning)

[greenberet]

To get back to your original question about how an increase in stroke affects ignition timing, I'm not sure if you've seen the following webpage: http://www.jcna.com/library/tech/tech0013.html. It lists various things that affect timing.

As RON98 mentioned, the flame front travels faster the higher the compression ratio. Therefore, all else being equal, the higher the compression ratio, the less ignition advance you should have in order to avoid detonation. When you increase the stroke of an engine, you increase the speed at which the piston is traveling and decrease the amount of time it is spending at top dead center. Since the compression ratio is highest at top dead center, the engine reaches that compression ratio for a shorter period of time. At the lower compression ratios around TDC that a longer stroke engine will have, the flame front will travel slower. So, all else being equal, a longer stroke engine will need more ignition advance than the standard engine.

However, if you change not only the stroke but anything else as well (compression ratio, piston top shape, rod length, etc.) all bets are off as to what the net effect on the timing will be. In any case, it should be tuned on a dyno.

Now as to the relative merits of a stand-alone EMS custom programmed on a dyno vs. a chip for the Honda EMS custom programmed on a dyno...

 

[Swift]

^ thanks for the help and the link. According to everything I have been reading because i have increased volume effieciency, better exhaust flow(slight porting and test pipes), higher compression, etc that i will need less timing up top. My new chip programmer is going to add 10% fuel across the board and i told him above 5k to retard it 3degrees compared to stock. Hopefully that will work.

I to am trying to run this as good as i can with a new ROM to then dyno and improve chip. Then when i go FI I will go AEM even though our map sensor is good to 10psi our ECU throws a code at 4psi.

 

[Bob Kenney]

I figured I would ask a technical question here since we have alot of very experience people here in regards to increasing stroke. My question is simple and yet I cannot think clearly to find the answer. The question is this: If you increase the stroke, lets say a 3.8L stroker kit, would the ignition timing need to be advanced or retarded based on the time it now takes to reach TDC? Longer stroke would equal slower piston speed but thats all I got.

thanks in advance.
Ben

Ps-If thread needs to be moved feel free.sry

Ben,

Going back to your original question and the statement you made concerning piston speed; I would like to clarify that the longer stroke means the piston is travelling faster. This is due to the greater distance the piston needs to cover in the same given time.

 

[RON98]

^ thanks for the help and the link. According to everything I have been reading because i have increased volume effieciency, better exhaust flow(slight porting and test pipes), higher compression, etc that i will need less timing up top. My new chip programmer is going to add 10% fuel across the board and i told him above 5k to retard it 3degrees compared to stock. Hopefully that will work.

I to am trying to run this as good as i can with a new ROM to then dyno and improve chip. Then when i go FI I will go AEM even though our map sensor is good to 10psi our ECU throws a code at 4psi.

wow good luck.

hopefully your increased VE and displacement only contributes to a 10% change in air intake and also 3 deg in igntion retard.

looking foward to hearing back from you about your results.

 

[Swift]

The chip is in the mail out to the guy burning it. I shortly will order a burner myself.

I also want to let everyone know that I do understand the need to go standalone in the future however at my current level I think a chip will do just fine so i can make it to the dyno BEFORE it lets go lol.

Also in regards to 10% change in air intake...yeah i may have to take that into consideration more. We did some math and comparisons before hand but I will look into it more.

Also thanks for clarification on piston speed etc. Helps alot and I finally got some straight answers.

Will update in about a month give or take.