tuning my sr

Discussions concerning the M7790 cpu

Moderator: Matt

PL
 

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Post by PL »

Yeah, RNN14 is quite a different engine. Different cams, I believe 8:1 compression (?) etc. I never cease to be amazed at just how different the RNN14 SR20 is to other "mere mortal" SR's. They really put some effort into them.

Don't try it on an S13! I've run my own car on 14 degrees at 14psi boost (98 RON fuel) and that was right on the ragged edge!

PL
Josh K.
 

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Location: Makawao, Maui, Hawaii.

Post by Josh K. »

it seems the knocklite output is a digital waveform...
PL
 

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Post by PL »

Yeah, I suspect they have some sort of serial comms so the knocklite can talk to their other boxes.

PL
Josh K.
 

Posts: 42
Joined: Fri Nov 16, 2007 3:30 am
Location: Makawao, Maui, Hawaii.

Post by Josh K. »

I have to chose between another knocklite or dyno time. if I tune my timing on the dyno how many pulls will I need? I was thinking 6 would get me close? whats the best way to ramp up timing to find the limits on the dyno?
PL
 

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Post by PL »

Hey Josh,

I wouldn't use the knocklite to tune until you have verified its operation with another method anyway.

You really shouldn't need to tune much at all.

1) First check mixtures.

2) Once they are right take a couple degrees timing out on the last 4 columns.

3)Get boost level where you want it.

4) Adjust dyno printout so you get the torque curve to take up as much of the screen as possible so that any changes are easy to see.

5) Check that engine temp is 85 degrees and do a baseline run.

6) Add a degree of timing and note the affect it has on the torque curve. It should show an increase across the range.

7) Keep doing this until torque ceases to increase. It's very important to be consistent - keep an eye on coolant temp mainly. But things like oil temp and even tyre temp can also influence things. Allow engine to cool down to 85 degrees between runs.

8) As soon as torque stops increasing you are at the detonation threshold. It may happen sooner in some places than in others. Adjust timing map to suit. The rough way is to just take a couple degrees out across the board as soon as torque stops increasing anywhere. Ideally you'll see it stop increasing pretty much everywhere at once. Then you know the overall shape of the curve is correct.

PL
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