V6 exhaust on LX

Nam1911a1

Well-Known Member
Joined
Aug 16, 2016
Posts
708
Reaction score
21
Location
Southern Indiana
So I have a f23 LX sedan. I have found a v6 accord for dirt cheap and I'm swapping parts over

Plan on doing the 5 lug conversion and put the factory Honda aluminum wheels on my car. The wheels have brand new tires so I'm golden there.

My question is will the v6 exhaust bolt up under my car? I'm assuming the exhaust piping is bigger than the f23 exhaust because it's a bigger motor.

I can weld the piping together after the cat. I just want some better flow and I'm not buying an exhaust system. I wanna use what I have. I am not after maximum power gains. Any gain is good.

Will it work?
 

Varnell

Well-Known Member
Joined
Mar 16, 2013
Posts
1,102
Reaction score
4
Location
Charlotte, NC
Its not a true dual exhaust, so welding after the cat will be fine. You'll probably need the exhaust hangers, too, since you won't have a hanger on the left side to hold up the muffler.
 

604ACCORD

Well-Known Member
Joined
Feb 6, 2014
Posts
601
Reaction score
6
Location
Vancouver BC
I went to auto store bought the v6 cat back oem setup and had mufflers welded on from what I remember pipe size is the same or at least looked the same the v6 just had a Y into 2 mufflers. Don't quote me on pipe size it's been a while since I seen an oem setup
 

Russianred

Snail Spools You!
Joined
Jan 10, 2007
Posts
9,455
Reaction score
50
Location
Southern Maine [207]
You definitely don't want a dual exhaist on your 4-banger. You will suffer with power loss and pisspoor gas mileage. You may also experience getting made fun of by those that know the difference when they seen your 4-lug wheels. Sounds like that may change though if you are 5-lug swapping! There are better single-outlet options out there, if you are not boosting mad power, then you will want all the backpressure you can get.

I noticed that I've posted in multiple threads of yours, all for things that may have been covered. Would it make sense for you to just create your own build thread with ongoing topics, versus making individual threads for each question/topic? Just a thought.
 

SupraGuy

Well-Known Member
Joined
Aug 30, 2016
Posts
124
Reaction score
2
Location
Edmonton, Alberta, Canada
Backpressure isn't what's desirable, appropriate flow is.

This is a subtle, but important distinction. A smooth flow is necessary to maximize cylinder scavenging during the exhaust stroke. When the exhaust is properly sized, this happens such that the inertia of the exhaust gasses through the system creates a low pressure area at the exhaust valve about the time that the next exhaust pulse is nearing its completion. The result is that the cylinder evacuates more efficiently, allowing the intake stroke to draw in more fresh air/fuel mix, and ultimately create more power. If you were to restrict the flow of exhaust such that there is greater than ambient pressure at the exhaust valve during this time (IE Backpressure) this would be worse performance, as the engine could not acheive it's potential volumetric efficiency (VE).

An exhaust too large will effectively keep ambient pressure at the exhaust valve all the time.

That said, I would think that the stock size piping from manifold to catalytic converter is probably enough to encourage proper exhaust scavenging, and if you really wanted the dual exhaust, you would probably need a dyno to measure any performance change. Most likely there wouldn't be a significant difference that couldn't be accounted for by the extra weight of the system.

All of this goes out the window when you're dealing with turbocharging. So far as I've been able to model, there's no such thing as too large an exhaust on the outlet of a turbocharger. For one, the turbo itself imparts inertia to the exhaust flow, trying to keep a steady flow despite the pulsed nature of the exhaust as the turbine blades regulate flow, and second the turbo depends on an energy gradient over the turbine, and the easier it is to evacuate the exhaust gas from the outlet of the turbine, the greater that potential energy. The turbocharged system is also much more forgiving of header design as well because of this. Equal length runners are still ideal, but offer minimal gains in a turbocharged setup.

In most normally aspirated engines, the exhaust system will be optimised for an RPM range, where the rate of flow can be managed in order to create that low pressure point at the exhaust valve at the appropriate time. this RPM range is usually placed to coincide with the throttle position (As it modifies the engine VE) and RPM that the designers expect the car to most need the efficiency boost. This tends to be "highway passing" so in the case of the F23, that's probably 4-5k RPM where you will get the most benefit. Of course there are also elements of cost and noise where the exhaust is optimised for.

If you want to move that efficiency band for racing, you probably want to bump it up to 5k-redline. there will be an exhaust size that does that, but most of those changes will need to be on the hot side of the catalytic converter, and not the catback. Of coruse, I'm not a Honda engineer, so I can't say for certain where the exhaust system is tuned for, but I'm absolutely certain that it was tuned.
 
Back
Top