Dual Exhaust Vs. Single Exhaust

[Chetan]

Hi,
I have a Honda 1.5 Vtech SOHC used car which has currently single exhaust, originally the model has one manifold and split the exhaust pipe after the muffler. Changing from single exhaust fitted by previous owner to origional one like “split exhaust pipe after the muffler” should I expect any change in avg or horsepower, please suggest.

–Chetan

Topic

[Steffen Nyegaard]

Nope. Makes no difference after muffler. Most straight 4s I have seen benefit more from single pipe systems.

[road2perfection]

[quote=”Nogood” post=51709]Nope. Makes no difference after muffler. Most straight 4s I have seen benefit more from single pipe systems.[/quote]

Having unequal length may give nicer sound, easier to muffle without restricting flow.
all this is walking into complex design territory and is not as easy as putting something together….

I muffle mostly everything after the cat where mine splits into twin 3″ before I have some larger sections and a racecat that improve the sound and doesn’t really give much restriction, as it travels to the end I have 2 glasspacks and 4 harmonic silencers bringing the noise level down to 92 DB.
end points are restricted to twin 2″ that result in the same as single 3″ but doesn’t have that sound comin out of a hole sound.
Stock is 86 DB, but the sound is better, and have taken a while to improve this design, slowly and trying out things, just taking parts testing out how they act on sound and then on power.

[Chetan]

alright, I wonder why my car responds better at 2.5k rpm & above & gets very sluggish below 2.5k rpm. Mine is 1.5 Vtech engine & pickup or throttle response of 1.5 (normal /non vtech) model is far better than mine. Compression is 200 psi per cylinder.

[joseph bullock]

i used to have a 2000 accord vtec, and drove it normally until a friend showed me how those engines were ment to be driven. from my understanding they start producing actual power at a high rpm. after he showed me, i was shifting at 5k and had high power with no ill effects on the engine. sometimes shifting at 7-8k.

[Chetan]

Thanks for your input, a local mechanic was able to reduce the lag by correcting ignition timing setting, and now my car responds quite better. Also local Honda service guys told me that Vtech kicks in at 1.5 K RPM & it is not only dependant on RPM but other factors like oil pressure, input from ecm, engine temperature & throttle response. One can reach high RPM’s even by a linear throttle accleration but a sudden acceleration most of the time engages Vtech operation.
Now for IVtech it is more different as it operated in three stages like low,mid & high rpm.

[Chetan]

Can you talk more on your testing with twin 2″ for power.

[Author]

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