Exhaust backpressure

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z 28 jari
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Exhaust backpressure

Post by z 28 jari »

Hi,
just make back pressure measurement from exhaust pipe(after headers and y-pipe).Pressure gauge reads at end of accelerate(6500rpm) 13kPa(~1.9psi) .Is this too much or acceptable backpressure?This is na 385 sbc.
RevTheory
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Re: Exhaust backpressure

Post by RevTheory »

I'd say it's good to go but it'll be interesting to hear other opinions.
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MadBill
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Re: Exhaust backpressure

Post by MadBill »

Here's grab from a David Vizard article http://www.superchevy.com/how-to/exhaust/0505phr-exh/
He suggests no more than 0.2 psi (~ 6" H2O), but as you can see, your 1.9 psi should only result in about a 2% loss from open exhaust power
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modok
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Re: Exhaust backpressure

Post by modok »

Trivial for proper mufflers.
Remember that's the average, not necessarily what the engine is seeing at TDC. Pressure can swing as low as half the average absolute pressure if header is tuned right.

IMO 2-3 psi would be fine at peak RPMS, in most cases.
z 28 jari
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Re: Exhaust backpressure

Post by z 28 jari »

Thanks for replys,I was little worried if exhaust system after headers is too small.Engine itself is somewhere 450-500hp range,headers+y-pipe are these: http://www.ebay.com/itm/Maximizer-SBC-E ... 1750439877
and rest of exhaust is one 3" pipe to dynomax ultraflow(3"in 2x2.5" out).
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