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oztracktuning
April 27th, 2006, 06:28 PM
I tuned a car today with a 218 224 114lsa crane cam - that ended up going fairly well - but it is idling at 64Kpa at 800rpm .....and reasonably smoothly!?

The full throttle Kpa drops as low as 95Kpa when Baro was 102Kpa.

Stock airbox
Shaved heads
extractors - exhaust

Is there is a reason for such a high idle Kpa - my car was a smaller cam and heads has 45Kpa?
caver
April 27th, 2006, 06:31 PM
The bigger the cam the higher the idle kpa.
If the manifold pressure is lower than atmo at wot then there is a restriction in the intake system.
I find that standard the manifold pressure drops above 4000rpm thats at 5000ft at sea level it must be worse.
Atmo pressure this run was 94kpa you can see the pressure drops to 88kpa. This is a bog stock car.
This was at a lower altitude than I live at normal for me is 85kpa

http://i2.photobucket.com/albums/y38/razzo/83e3b704.jpg
Tordne
April 27th, 2006, 09:18 PM
You could also try playing with the timing and AFR at idle as I have found that that can affect the idle MAP as well. My car currently is stock cam :frown: but I suspect it will make the same (or perhaps more evident) difference on a cammed car.
GMPX
April 27th, 2006, 10:16 PM
I have a slightly larger cam and 112lsa, and it idles around 62kPa at 700RPM in gear, 22deg timing, 14.6:1 AFR, WOT MAP can be between 95 & 98kPa. Idles much nicer at about 13.8:1 AFR's but smells too much.

I also looked at some logs when it was stock (apart from exhaust and headers).
Idle at 40kPa at 600RPM in gear, 26deg timing, WOT MAP 100kPa :Eyecrazy:.

Cheers,
Ross
TAQuickness
April 27th, 2006, 10:58 PM
I tuned a car today with a 218 224 114lsa crane cam - that ended up going fairly well - but it is idling at 64Kpa at 800rpm .....and reasonably smoothly!?

The full throttle Kpa drops as low as 95Kpa when Baro was 102Kpa.

Stock airbox
Shaved heads
extractors - exhaust

Is there is a reason for such a high idle Kpa - my car was a smaller cam and heads has 45Kpa?

Interesting... I'm on a 238/242 115 and I get 55-58 kpa at idle. On a 103 kpa day, I can get 103 kpa in the manifold till about 3500, then it drops to 102