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EA Modeling of a Chevy 292 Inline Six, Siamesed Ports

General engine tech -- Drag Racing to Circle Track

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Cris
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EA Modeling of a Chevy 292 Inline Six, Siamesed Ports

Post by Cris »

I am hoping someone can give me some guidance on modeling a chevy 292 inline six on Engine Analyzer Plus. My sticking point is how to deal with the siamesed intake ports. The ports are siamesed in both the head and intake manifold. Presently I am assuming I use the full area of the siamesed port for each cylinder since the firing order is far apart for the shared ports. Any help would be appreciated.

For information:

The firing order for the 292 is 153624. One and two share a port, three and four share a port, and five and six share a port.
ProPower engines
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Re: EA Modeling of a Chevy 292 Inline Six, Siamesed Ports

Post by ProPower engines »

Questions Regarding Siamesed Intake Ports (9 Port Head)
See thread below 2nd from bottom of page
Real Race Cars Don't Have Doors
Cris
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Re: EA Modeling of a Chevy 292 Inline Six, Siamesed Ports

Post by Cris »

ProPower:

I had seen the thread started by Enigma57. I am hoping he will see this thread. Not sure where he ended up for a model, one approach mentioned in the thread was to treat the siamesed port as a large plenum until the ports diverge in the head. This would leave relatively short port lengths.

Thanks, Cris
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Re: EA Modeling of a Chevy 292 Inline Six, Siamesed Ports

Post by panic »

The pairs do not have the same crankshaft rotational interval for their intake strokes.
The 1-2 is 240-480-240, the 3-4 is 360-360, and the 5-6 is 480-240-480.
This affects jetting: the even interval required richer jetting (per Jaguar specs)
Cris
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Re: EA Modeling of a Chevy 292 Inline Six, Siamesed Ports

Post by Cris »

Panic:

The most problematic for the model is when the 1/2 and 5/6 cylinders are 240 degrees apart. I am trying to model the stock performance first and the cam has only 188 degrees of duration with a 111 LSA. My hopes are, though there is some overlap with 240 degrees of separation, the effect is minimal with the small cam. The other cases of 360 and 480 degrees of separation have very little or no overlap.

I have been playing with the model and the best match I am getting to GM measured data for torque and horsepower comes when I model the siamese ports as (large) plenums. The intake port length is very small for this case.

Here's the GM plot and the EA calculated profile of HP and torque.
292 Horsepower Graph.docx
EA Model Resutls.docx
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