exhaust thoughts

[athoose]

The stock exhaust system, 73 620 L-16, is not a 4-2-1 it

[banzai510(hainz)]

dont worry about it!!!!!!!!!!!!!!!!!!!dont make this hard on yourself

[RacnJsn95]

Not sure about gains, losses, etc, but the way I built my y-pipe was just so I could make the merge easy, seeing as I had limited tools at the time.

 

I've always read a 4-1 is better for low end torque, and a 4-2-1 is better for top end, but I highly doubt you'll notice a diff either way.

[Pacific coast Datsun]

It's an L 16..not gonna notice any difference. Other than sound.meaning muffler choice & or size of the pipe.

[datzenmike]

The '78 and up L20B (maybe all?) are basically cylinder #1 joining #2 and #3 which seem to join together just after leaving the head, and #4 coming in from the back to make one big single pipe.

[fiveNdime]

Yeah, I think performance isnt going to be a major deal, but I would stick with trying to get more bottom end which you need all you can get with a 16. I wouldn't go much more then 2.5" pipe and keep some back pressure.

[agentalpha]

I've always read a 4-1 is better for low end torque, and a 4-2-1 is better for top end, but I highly doubt you'll notice a diff either way.

 

Actually, ya have it switched.

 

 

And I wish people would quit saying "Backpressure".

You NEVER want "Backpressure", and it's a BS ignorant term anyways.

I HATE that frigging word. Almost as much as "upscale".

 

What you want is to keep your exhaust temperatures hot, thereby velocity up.

If the gasses are allowed to expand, they cool, and slow down, basically clogging your pipes, as the engine has to work extra hard to pump them out.

Edited January 12, 2009 by agentalpha

[ggzilla]

Yes, agreed, fast flow is what is important. But if you make the pipe too big that slows down. Exhaust piping needs to be the "right" size, not just "bigger is better".

 

As to 4-2-1, tri-Y or equal length, etc. -- Sure it'll make a performance difference. Instead of 125 HP, you could be getting -- just by rearranging the header pipes -- oh say 126 HP. You decide if it's worth that. Many racers feel it is, difference between winning or losing by a hair.

Edited January 12, 2009 by ggzilla

[athoose]

So it sounds like minimal difference on this application. Though, one horse here and there on 70 hp motor is large. :) I need new exhaust otherwise I wouldn

[fiveNdime]

Actually, ya have it switched.

 

 

And I wish people would quit saying "Backpressure".

You NEVER want "Backpressure", and it's a BS ignorant term anyways.

I HATE that frigging word. Almost as much as "upscale".

 

What you want is to keep your exhaust temperatures hot, thereby velocity up.

If the gasses are allowed to expand, they cool, and slow down, basically clogging your pipes, as the engine has to work extra hard to pump them out.

 

Backpressure:fu: