What ratio to cut C14 for street cruising/ putting around.

General engine tech -- Drag Racing to Circle Track

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MAT
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What ratio to cut C14 for street cruising/ putting around.

Post by MAT » Tue Apr 12, 2005 7:29 pm

4.5x4 509ci iron head BBC (fully ported 280cc oval World), true 13.7:1, 280/288@50th soft ramp roller, 5K 9" converter, prosystems 1088cfm nitrous pro IV carb, stock rod length, 113cc open chamber polished, all hard edges rermoved from domes. Water temp stays below 185F at the top of the intake manifold.

I run C14 / 38 degrees at the track - 94 jet squared from the dyno tune.

I want to cut my race fuel with 94 octane Sunoco 94 10% ethanol fuel - just to cruise around with (1200-4000 rpm, all on the primaries, well below torque peak, always under high intake vac.)

How light a load of fuel can I run? I have one multistep retard on the shifter, so it's no problem to pull 4 degrees (eg) if I have to pass someone.

I am familiar for looking for detonation signs on plugs for N20 tuneups, but don't know if a light rattle would show up this way.

Please lend a hand,

MAT

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Walline
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Post by Walline » Tue Apr 12, 2005 9:13 pm

I have ran a Static compression SBC with 115 Sunoco and 92 pump gas mixed 50/50. The dynamic compression was 9.72. I limped it around on the street a lot. I ran it locked down with 36 total at the track and would pull about 8 out of it on the street. It did not like hot days, I must say, but cool nights seemed to be fine.

mars
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Post by mars » Wed Apr 13, 2005 11:05 am

Mat, with that much cam, and that loose a converter, drop a little timing and use 100% pump fuel.
You will not get into detonation, as the cylinder pressure will be way down with the throttled engine, you will be fine.
Use the race gas come race day though..
How many degree's past BDC does the intake close ?
Have you done a compression test on this eng ?

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