adjusting the ignition timing and higher compression pistons

[pj91gsx]

My brothers dsm has wissco pistons with 9.1 compression if I remember correctly. Do I need to set the ignitioning timing to a different degree than stock?

 

[Gamble97]

No. WTF

 

[1992awdlaser]

You have something to tune with, right? Lower the ecu timing adjustments to start with. You don't need to lower base timing unless you have nothing to tune with that has a timing adjustment, you still might not need to change it. It just depends on if it knocks at the boost level he wants to run.

 

[pj91gsx]

I do not have anything to tune with. My brother built the motor and is now selling it, so Im getting it running. I put a cylinder head on it, fixed all the boost leaks, and set the ignition timing to exactly 5 degrees btdc. On the boost gauge it reads a little less than 9 lbs for the max boost. The car idles well at 750 with the ignition timing at 5 btdc. Should I just experiment to get it right by changing the timing to where it runs best? Should I retard the timing or advance it? Just thought I might add, the car is not fast.

 

[1992awdlaser]

Leave it at 5* unless it is knocking. If it is knocking, retard the timing.

 

[toofast82]

WOT+ 9:1+ stock 1g timing+91-93 octane+high boost=BOOM

 

[pj91gsx]

WOT+ 9:1+ stock 1g timing+91-93 octane+high boost=BOOM

Do you have an explaination of why it =boom?

 

[blazebolt]

The stock 1G has lower compression pistons (7.8CR), and you just increased it to 9.0. On top of that the stock 1G timing curve is very aggressive because of the low compression and with higher boost you increase the Final Compression Ratio even more. Combine all that with 91-93 octane = knock city = boom

Things you can do would be to lower timing, lower boost, meth/water/alchy injection, or E85/race gas. For a street car I would do the first two.

 

[pj91gsx]

I see what your saying, Im running stock boost, so I'll work with it.

UPDATE: The car runs best with the stock ignition timing, but i can hear a loud constant knocking coming from the engine. This engine was rebuilt about 50 miles ago. The timing belt spun off a pulley and my brother was convince that there were going to be bent valves. The loud noise that is being made now was being suspected of being bent valves. My brother things it can be a spun bearing on the crankshaft because the crank was polished by the machine shop and it may be egg shaped. Im getting my brother to check the bearing tomorrow to see what we can find.