boost timing retard.

[mulot30th]

We all know the 1deg timing retard per # of boost rule of thumb

But if someone want to go very high boost, 35# of bosot for an example to be extreme.


and the timing retard kick in at lets say 15# of boost.


is there a logical limit as to how much timing to pull max??


because in this extreme case it would be a whopping 20deg timing retard at 35# of boost... can't imagine it would produce much power at all with so much timing retard.


And let assume a 36 deg base timing (as hurricane says) .

 

[Wildman]

You can run 35 lbs by pulling 10 degrees out threw the peak tq curve & then putting 2 to 4 more back in down track. Vp import fuel will allow you to do it. We have a stock compression rx-1 motor right now running full timing at 27 lbs of boost. This is all for 660' ice though. We did lift the head on one at 25lbs of boost on a stock compression running c-16. Import fuel allows you to run 6 to 8 degrees more timing than c-16. We have seen on the rx-1 motors that after 12 degrees of timing is out they really lay down. For racing 660' I would rather run 25 pounds of boost with stock compression and more timing. You get into the 1000' speed runs I could see the lower compression, bigger turbo, less timming and more boost for the big end power. Keep in mind these examples are running on the edge.

 

[mulot30th]

C16 racing fuel, 10-1 compression ratio

20,25 and 30 psi boost

total timing advance would be around what at pktq and pkhp?

 

[Wildman]

Do you have any dyno runs on this engine as this would help to see were the pk tq is made on your engine (everyone is a little different).

 

[mulot30th]

I have no full dyno pass.

But being a centrifugal blower, peak torque will be at whatever rpm I clutch it for.

lets say 10800 rpm

 

[TWIN TURBO]

Wildman has the right idea. Avoid Big timing at peak Torque, 9000-10000 RPM I would also add very IMPORTANTLY A/F Ratio will make a big difference on what you can do with boost and timing. A simple equation More Boost + More Timing + More Fuel + More Octane = More Power up to the point of detonation Then 0 power!!!
Tip of the day is get away from the 2 stroke mentallity that leaner makes more power. WRONG It takes fuel to MAKE power Let the engine have it.