(Research) Dual Exhaust / Larger Front Pipe for Solara V-6

[PhreakdOut]

Every once in a while, our company buys a complete exhaust system from Toyota on new model vehicles. (These are systems that we do not currently make. AKA competitor's parts.)

Last friday I picked up the system for a 2005 Avalon. I knew there would be similarities to the Camry / Solara system, but I didn't expect this much.

Why do I post this information? I figure there have got to be a few crazy persons out there who are dying to do something different. I'd never expect anyone to buy the Avalon parts, modify the hell out of them and install it on a Solara. Custom exhaust is cheaper.

As soon as our company is done with these parts, I'll see if I can fabricate a dual system out of the parts.

Here's some images and my observations:

Camry Solara V-6 system:


note the area I marked in Red. (Fuel evaporative cannister?) This would need to be shielded if a dual exhaust were to be routed here.

Here's the 770N '05 Avalon

Note the area in question is not a problem. (I may research if we can use the 05 Avalon cannister in order to open up this area.

Also, the spare tire well is more narrow on the Avalon. Allowing the dual exhaust on the driver's side. (Or the car is wider in general.)
However, note that the routing of the center pipe with the Y for the dual runs down the same path.

(I apologize for the poor resolution on these next few pictures. The only camera handy at the time was in my phone.) I'll replace them with better pictures after I return from Japan.


The Solara pipe is on the left and the Avalon pipe is on the right. The routing is close, but the Avalon system is longer by 3-4". The flange rotation on the outlet of the center pipe is different. Avalon's seems better for reaching the upper bolt when installing on car. The Avalon submuffler (resonator is a larger diameter. I'd estimate it's a 150mm vs the 120mm on the Solara.

The front pipes: Avalon on the left, Solara on the right.

The length and routing is almost the exact same. The Avalon pipe has larger diameter down pipes from the manifolds. However, the flange rotation has changed again on the second inlet. A good welder could cut the flange and pipe loose , rotate and reweld. Again, the fabricator's got to be good. The bad side is that that converter comes with the front pipe. This means it's un-godly expensive. (I won't say how much Toyota marks up their service parts with converters, but I can tell you it's just short of 9x the cost. My biggest complaint on Toyota service parts.)

The dual exhaust ...
Here's the famous "photo-shopped" dual exhaust. (Remember - this picture is fake. Nicely done, but a fake.) My compliments to the originator.


Because of the tight clearance on the driver's side, it will be VERY difficult to fabricate a pipe to route around the spare tire well and exit in a symmetrical spot as the current exhaust cutout. (I'll take underbody pics later.)
The entire driver's side must be completely custom. There's not enough room for a full sized muffler. So I'd recommend a polished "Bullet" style resonator less than 4" in diameter. Not much would be needed on that side anyway due to the extra length in pipe and additional bends. (Compared to the pass. side exhaust.)

Again, I'll take a stab at making the dual portion work sometime in June. (Just before the show at Elmhurst Toyota on 7/10. )

One way or another, I'm going to end up with a dual by this summer.

I created this post so I can update the progress. Please comment or add on if you have tried to make a dual for the Gen2.

[dvdchris45]

I got a question. Don't we have to make a cut or some type of groove around the left side of the bumper for a proper outlet?

P.S. This Avalon dual exhaust does sound promising. Good luck!

[JayDubz]

Nice work, very interesting.. I know when i purchase my car this fall/winter.. i will def, want to get dual system.. and with research already under way it will be way easier to take to a custom exhaust shop and get more accruate cost of whole project... But yes please keep up the good work.. good luck with the dual setup...

[PhreakdOut]

I got a question. Don't we have to make a cut or some type of groove around the left side of the bumper for a proper outlet?

Yes. This has me a little nervous. Screw ups are expensive here.
I will not attempt the cutout myself.

Atleast the body kit portion is easy since it can be removed and cut. The arch in the bumper is another issue.

[MikeATL]

how would a dual exaust setup effect performance?

[PhreakdOut]

how would a dual exaust setup effect performance?

I'm, not sure at this point. The key is finding where the flow restriction is in the OE system. (In the muffler, resonator, converter, Y-pipe...)

In this case, the most apparent restriction is in the Y-Pipe. Here, two pipes at 42.7mm OD are flattened into a "D" shape and forced together into a 51mm ID pipe. (See my sketches)




As I calculate the area for just one of the 42.7mm pipes, I see this much of a reduction:

42.7mm OD (t1.5mm): area inside the pipe = 1.92in
D-Flat pipe (½ of the joint): area inside the pipe = 1.29in

The resonator is straight through with very little restriction in diameter, so I don't see much gain there.

The OE Muffler has a valve on the outlet pipe exiting the muffler. This valve opens a few mm when backpressure is enough to overcome the force of the spring keeping the valve closed.

I'd expect there to be some gain at upper end of the RPMs. Bottom end is not terrible (with exception to the throttle lag issues.)

[Astro]

This is awesome, I hope to put dual on June's ride soon.

[michaels artic frost]

Keep us posted Brian. Great work on the pics and research!

-M

[mmcdonald]

I would be interested in a custom solution if anyone knows anyone in MD that can do this, around Columbia.

I think a single exhaust with a 3" pipe would be better than a fake dual. Having been brought up on V8's with true dual exhaust systems, I know a single 3" would be fine. If you push 2.5" on a V8 dual, then you are doing really well. A single 3" on a 6 would be okay, I think.

In any event, the construction on the Avalon system looks like crap. That bend in the pipe where it splits to the dual pipes scares me. That can't be good for performance.

I want the real performance, not the look.

[mattyboyl]

I would be interested in a custom solution if anyone knows anyone in MD that can do this, around Columbia.

I think a single exhaust with a 3" pipe would be better than a fake dual. Having been brought up on V8's with true dual exhaust systems, I know a single 3" would be fine. If you push 2.5" on a V8 dual, then you are doing really well. A single 3" on a 6 would be okay, I think.

In any event, the construction on the Avalon system looks like crap. That bend in the pipe where it splits to the dual pipes scares me. That can't be good for performance.

I want the real performance, not the look.

You have a valid point. I noticed the Avalon layout and the bends around the gas tank are almost 90 degrees. That is a huge restriction. You look at our exhasut setup and it is pretty straight through until you go into the muffler. A dual setup for us will give us no more performance than a single outlet unless you could do a true dual, which I don't think is possible on our cars. If you go dual you will get no more performance thana single outlet setup. I personally was contemplating dual exhaust. When I looked under the car this past weekend, I noticed the cutout would not be in the same spot as the other side which would look bad with the body kit. We need a custom rear lip to give the rear a clean and symetrical look.

[Astro]

This is how my rear y-pipe bends on my gen1, which is almost 90 degrees. Which probably wouldn't be much different in the gen2.


If you have the money, why couldn't you go true dual? Greg did it in the gen1. I think it's possible with the gen2.


edit: What's up with the red x's, the pics showed up fine on my preview?

[Mandarinsolara]

i miss the autocad days
... thanx for the good flashback

[PhreakdOut]

I would be interested in a custom solution if anyone knows anyone in MD that can do this, around Columbia.

I think a single exhaust with a 3" pipe would be better than a fake dual. Having been brought up on V8's with true dual exhaust systems, I know a single 3" would be fine. If you push 2.5" on a V8 dual, then you are doing really well. A single 3" on a 6 would be okay, I think.

In any event, the construction on the Avalon system looks like crap. That bend in the pipe where it splits to the dual pipes scares me. That can't be good for performance.

I want the real performance, not the look.

You have a valid point. I noticed the Avalon layout and the bends around the gas tank are almost 90 degrees. That is a huge restriction. You look at our exhasut setup and it is pretty straight through until you go into the muffler. A dual setup for us will give us no more performance than a single outlet unless you could do a true dual, which I don't think is possible on our cars. If you go dual you will get no more performance thana single outlet setup. I personally was contemplating dual exhaust. When I looked under the car this past weekend, I noticed the cutout would not be in the same spot as the other side which would look bad with the body kit. We need a custom rear lip to give the rear a clean and symetrical look.

You both have excellent points. There's no NEED for dual exhaust on the Solara. The reality is that it would just look good.

A single exhaust would be just fine if performance is what you seek. However, I caution the use of too large a diameter pipe. Oversized pipes changes the pitch but not necessarily the flow. They lose their effectiveness at that point and end up just adding weight. Find the smallest diameter in your system and go with 1/4" larger pipe.

The dual system though, is a matter of style. I think the rear of the SE needed the dual to make the car look right.As Mattyboyl pointed out, the driver's side would look wrong if it came straight out. It would require a tricky pipe with overlapping tangent points in the bends in order to exit in the right spot.

I love a challenge.

[PhreakdOut]

i miss the autocad days
... thanx for the good flashback

Event though we use Catia and Togo/Caelum for our 3D CAD, I still whip out the old school AutoCAD for the simple stuff.

[Mandarinsolara]

i miss the autocad days
... thanx for the good flashback

Event though we use Catia and Togo/Caelum for our 3D CAD, I still whip out the old school AutoCAD for the simple stuff.

gettin all fancy now arent we?
Autocad was a pretty sweet class for highschool
especially the freakin lan parties we would have when the teacher wasnt around. played like liero x and doom and all kinds of sweet games.

sorry to get off topic. what are you using this for? engineering school or something?