Dual Exhaust Question

[gmtofd]

On my Malibu, and the daughter's Monte SS, that both have semi-mild 350's been using basicly, the stock Monte SS set up. The daughter's is a Dynomax set-up,. It's a duplicate of the stock Monte SS except for 2.25 whereas the stock is 2 inch. There are FM super 40 muffs because she wanted noise. amd tail pipes to the bumper As you may or may not know, the Monte SS set-up uses a single bell month converter cat. IMHO, the OEM bell mouth converter would not be a flow restriction for something making up to 400HP. For headers, both are running ceramic coated Edelbrock, which unfortunately are no longer available.

The Malibu uses a 2.5 inch section from the converter to the muffs, Super Turbo Dynamax muffs, and GN style 2.5 inch tailpipes. This is a less restrictive flowing of the two systems, but regret not going with 2.25 size tailpipes.

 

[gmtofd]

thanks for the detailed reply...why do you regret going with 2.5 tailpipes?

Neither car is ever raced and IHMO, the 2.25 tail pipes may of provided a little low end torque. If the Malibu was street/strip, then the present 2.5 tailpipes would of been the correct choice.

 

[gmtofd]

Notice that Summit sells a Monte SS style catalytic converter: http://www.summitracing.com/parts/mpe-93440/overview/make/chevrolet/model/monte-carlo but it's not the same dimensions as the OEM converter and IMHO will not flow as well. The OEM bell mouth converter was also used on C4 Corvettes. Suppose the answer would be to try and locate a OEM converter thru the Monte SS and Corvette C4 forum. Of course the concern buying used would be whether it's clogged-up.

 

[axisg]

x2 on the Monte SS exhaust. I am running Edelbrock TES Headers, Hi-Flow cat ( hollow ), and 2.5" Mandrel Bent Cat Back. Its a Torque Tech System and it was $ 450-$ 475 IIRC shipped to my dock in Mississauga appx 5 years ago. ( there was a guy on Kijiji for a year or so flogging a complete system for $500 or so )

If I was over 400 hp then I would take the risk and run a true dual system,

FYI, I was warned the Smog Nazi ( MTO ) can fine you for dual exhaust as the gbody was never offered in that configuration. As an alternative I have seen GN Guys run a 3" Cat Back system which is a single pipe & muffler. Sounds pretty mean and it's cheap

Single System

Professional Service

www.torquetechexh.com

 

[t5montecarlo]

They nail you because the car was only certified with 1 cat. You are not able to deviate from what was certified.

 

[Doober]

Interesting... here in AZ you can run more, but not less than, what the vehicle came with.

 

[axisg]

First off, I know its a slippery slope, below is the knowledge I have gathered over the years ( theres not much LOL ).
There have been rounds and rounds and rounds of bench talk about this since Drive Clean came in to effect in 99. Everybody seems to have their own opinion about what they are comfortable with and how "legal" they want to be ( or think they are ). Ultimately its up to the Officer and if you disagree with the officers opinion then ask the Judge as to what you can and cannot do. FYI the last couple years MTO has been at the occasional car show at 400 & 7 , 427 & Queensway, and Californias on the QEW randomly pulling over a very small number of vehicles for inspection as people leave the show. They have been known to walk thru the car show as well and boy a lot of hoods are closed fast !

Per below the Gbody falls under 2 categories for emissions exemption from Driver Clean ( pre-88 and/or Hot Rod ). MTO Link below

http://www.ontario.ca/environment-and-energy/drive-clean-test

Pre-88
This means that provincial officers — anywhere in Ontario — are authorized to stop and inspect your vehicle if they believe:
• your vehicle is emitting excessive exhaust smoke
• emission control equipment has been tampered with or removed

Hot-Rod
** if you can prove your vehicle had a motor swap pre-99 then you are exempt but the vehicle must meet or exceed 1980 emissions levels
- Otherwise
• Vehicle cannot legally operate if there are visible emissions for more than 15 seconds in any 5-minute period
• For Drive Clean testing, the vehicle model year is the model year as designated by the manufacturer
• Vehicle must meet or exceed what were the emissions standards for the original motor when all original emission control equipment was functioning
• All emissions control equipment must be attached and functioning (equipment refers to what came with the replacement motor or be equivalent to what would have come with that motor)


So if you can prove the motor in the car currently was orig equipped with dual exhaust and dual cats then you will be OK, otherwise it could be considered tampering. Everything else is up to the discretion and knowledge of the officer ( which is typically limited to a visual inspection of the EGR, Charcoal Canister & Cat Convertor ) then they may send you off to be tested.

So in my case I got the used TES Headers for cheap, plus a used / gutted hi-flow cat and then started saving for my cat-back. The exhaust in my car is Quasi-legal but able to pass the "visual" inspection for a regular V8 Monte Carlo. Under the hood I have the stock air cleaner, EGR, PCV, and Charcoal Canister all "hooked up" to my stock looking "305". ( you can figure for yourself what is in-between the " " )

I know a guy who is really struggling with this now as he's building a Twin Turbo LQ9 in a Gbody and he's trying to figure out exhaust options ( he used to run the 3" single exhaust on his GN ) as he wants to drive it daily in the summer and doesn't want the hassle of the MTO flagging his car. His friend ( my trans builder ) had his SBC w/blower Powered '39 Furd run thru MTO last summer and he ended up with a bunch of fines ( court case pending ).

Can you say Cash Grab ??

 

[LS6 Tommy]

I will challenge any officer inspecting the car and fining us for 2 cats on a dual exhaust.Ill fight it in court and use the excuse that I am exceeding polution standards by doubling the amount of COs by 2 cats...
as for egr,charcoal,pcv, all good, motor is 100% orig and stock. No chrome.

IDK about Canada, but you'd lose that if you tried to take that to court in the USA. It's not legal to replace a cat without showing receipt from your shop that the OEM one was faulty...

Tommy

 

[axisg]

I will challenge any officer inspecting the car and fining us for 2 cats on a dual exhaust.Ill fight it in court and use the excuse that I am exceeding polution standards by doubling the amount of COs by 2 cats...
as for egr,charcoal,pcv, all good, motor is 100% orig and stock. No chrome.

I would be interested to know what your Tech Friend says when he's back. I know there is the risk with dual cats too far back in the system to not get hot enough to operate efficiently and ultimately produce more emissions and end up clogged. Again not knocking it because before my next motor swap I too will be running true dual exhaust and cats myself ( likely with cutouts as well ).

 

[malibuguy]

So my incentive for moving to canada has been removed...