Welcome to our Site for MG, Triumph and Austin-Healey Car Information.
MG MGB GT V8 Factory Originals Technical - V8 Exhaust
|Please help me with the exhaust requirements and problems. I am putting 2 inch headers on my V8 engine. I do not want dual exhaust but want to merge the headers into one common exhaust pipe. What are my issues? Thanks. Jack|
|Unless you are running a BBC or other very large motor you do NOT want 2" headers.|
1.5" is more than enough for a Rover, 1 5/8" is even on the large side. Take into consideration that the 5.0 guys are all running 1 5/8" as a upgrade and those motors are 100cid larger and flow lots more air.. Too big a header will drop backpressure and hurt torque.
I would say 1.5 or 1 5/8" header tubes into 2 or 2.5" single exh out the tail would be perfect.
If you are handy with a welder, get some bends from your local muffler shop and start piecing it together.. HArd to know what issues you may have without being under your car..
|I was gonna say 2" is WAY too big for our cars. I did basically what Larry said. RV8 headers going down to a single flowmaster under the drivers seat, and a single pipe going out the back. Sounds JUST like a 5.0 Mustang. Lots of people ask me if there's a 5.0 in it it sounds so good! I would recommend putting a heat shied between the muffler and the floorpan. Sometimes my floor gets so hot I can smell the carpet melting -- not good.|
|Guys, I seriously doubt Jack was referring to the size of the primary tubes. More likey 2" is the collector diameter. |
Jack, unless you are running big HP a Y pipe into a single 2.25 or 2.5 will more than do the job. There are no issues. More of us run single exhaust than dual. You might want to seek the help of a reputable muffler shop.
|On my first V8 conversion (before going to dual exhaust) I used the block hugger headers with a Y pipe into the aftermarket Monza exhaust system that I used with my stock 4 cylinder engine. I purchased the Monza system through the British Victoria catalog. I have a 78 MGB but when I ordered the Monza exhaust I ordered the one for an earlier year that did not require a catalytic converter. Never had a problem passing emissions with the 4-cylinder engine or the V8 with that exhaust.|
I however really appreciate the sound coming from dual exhaust with the V8; there just isn't any comparison, to me the duals sound so much better!
|Michael S. Domanowski|
|That they do Mike, and I'm sure they help more than a little when you hit the nitrous, eh?|
|Hi - Thanks everybody. I was referring to the collector diameter. These are R8 headers I bought with the engine from D&D out of Michigan. I thought that I might have an issue bringing the headers into one exhaust pipe. I am trying to select the proper sized pipe so as to not lose much of this expensive horsepower I bought. The muffler(s) might be an issue too? I appreciate your comments and further advice. Jack|
I'm about to do what you're doing. I'm thinking 2-1/2" exhaust, but welcome suggestions. Flowmaster 500 series mufflers are supposed to fit well, but I haven't decided whether to locate the muffler under the l.h. seat, or back under the boot floor. Also, an outfit called Genesis, 1-800-274-8437, a division of Thermo-Tek makes some modular mufflers that might be worth looking into. You can bolt sections together to make it quieter or louder, different sizes, stainless, hi-flow, etc, they say. Also, there's a picture of the exhaust system under the car at: http://www.mgcars.org.uk/v8_conversions/engine/rv8man/exhaust2.jpg. Sorry, still don't know how to make hotlinks here. Best, Joe
|Jack, I just completed my exhaust system with a setup that might work for you. I used RV8-style headers with 2-inch collectors. I ran 2-inch pipes from the collectors to a Flowmaster Y-Pipe that has dual 2-inch inlets and a single 2 1/2 inch outlet. A Flowmaster series 50 muffler that fits beneath the drivers floor connects directly to the 2 1/2 inch outlet from the Y-Pipe. A 2 1/2 inch tailpipe and Hooker Header chrome tailpipe extension finish off the system. Sounds real good! Rod|
|Is the dualies' better sound due to the stereo effect, or what? For my conversion -- in process; going OK, thanks -- I'd like to keep a single tailpipe because I think it looks more MG-like ... or would that sound worse and be less efficient than a true dual setup? I guess the compromise would be to rig a dual setup but have both pipes right next to each other on the LHS of the rear valance.|
|A friend has one of Towery's 4.6 liter GT's with duals exiting together in the stock location. The left muffler is under the driver in a north-south attitude with the right one under the passenger area yawed about 30 degrees. No balance pipe. It sure sounds good.|
|For just about any V8 with medium power and street driven car. The primary pipes should 1 1/2 or 1 5/8|
With 2 collector, and like Carl suggested use a "Y" pipe with single exhaust into a single 2 1/2 using a free flow muffler from Dynomay. This will produce the must torque from idle to about 6 thou rpm and if larger collector then larger single pipe for lots of hp output engines. Many racecars use the single exhaust with a Y pipe.
|I beleive the reason for the use of smaller primaries is to keep up the speed of the gasses exiting, not to create back pressure. The only engines with which I am familiar that require a certain amount of back pressure are crankcase scavenged two-strokes. Repowering truck specifications will only show a maximum backpressue figure, with no minimun.|
|Jack...THere is a stainless steel y-pipe available for the MGRV8 headers. I got mine from D&D. |
|You might want to think about shifting your hydrolic clutch line, pointing it forward, it's a little close to the exhaust.|
This thread was discussed between 04/06/2003 and 09/06/2003
This thread is from the archives. Join the live MG MGB GT V8 Factory Originals Technical BBS now