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MG MGB GT V8 Factory Originals Technical - MGC - V8 exhaust system question.

Has anyone seen the twin exhaust system for the MGC
sold by the MG owners club ?
The twin pipes are routed in parallell all the way
and they are exiting on the same side if the car.
Connecting the two pipes to the V8 manifolds should not
be that difficult.
Could this be an alternative to the single pipe exhaust ?

Jhonny Sokura

Jhonny, if you want to run a dual system;
1.Start off with, at the least a pair of RV8 style manifolds,
2. Have Mike the Pipe build the rest of the system for you to
include a balance pipe joining the two separate exhaust pipes
just behind the bell housing,
3. Move the tank over, and make a little notch in the rear valance
to accomodate the second pipe.

Running a dual system with RV8 manifolds is of course an
option. My thought was that by using these MGC pipes one
could increase the breathing capacity in a simple way by
connecting the pipes with homemade adapter to the manifolds.

Jhonny Sokura


I follow your train of thought but have doubts as to the efficiency of the twin 'Downton' style system being able to provide any worthwile improvements over a single pipe system. The MGC even in tuned form was never rally pushing the performance of even a mildly tuned V8 and I think it may actually be restrictive in that use. I had given that route some thought before, as I have the RV8 system. My end choice will be a single pipe system, but the idea of a twin pipe system of the style of the MGC twin is not forgotten, but would be an item created specifically for the V8.

Roger Parker Tamworth


I assume that if this 'Downton' system is too restrictive a
'home mode' twin parallell system would need larger diameter
pipes and some other type of silencers too.
Something like the PECO HDR for each manifold if one only could fit two silencers in parallell at the rear.


PS. I'm off to Greece for a couple of weeks so I won't be reading this BBS for a while.
Jhonny Sokura

Yes this would be the first route to investigate. I know that at least one car recently featuired in the MG press followed this route. Quite what is best needs some comparitive testing that hasn't (as far as I am aware) been done.

Roger Parker Tamworth

Why do you want a dual system? Here in Australia we still have a lot of performance V8 cars. In fact, one of them has just been launched in the UK, the Holden HSV.

The go now days is a large bore single system, 3-4 inch diameter. This is a lot simpler than a twin system and probably a lot lighter to boot.

You havent heard a properly balanced BV8 dual system when the engine getson the cam
David or you wouldnt ask!
It also looks nice!
BobP to David

You got that right, BobP! Us 'Murricans over here have known about the sound of Duals on V-8s for years, from the mellow burble at idle up through the high revs.

If it weren't for the fact that I am doing a totally stock Factory B-GT V-8, that would be my first modification. Of course, maybe I will tire of the show circuit in a year or so, then it will be time for the duals, and the RV-8 front suspension, and the air conditioning, and the Doug Jackson composite rear springs, and and....YAAAHHHH!

(The last we saw of Paul Kile, he was being hauled off by two guys in white coats with mosquito nets...he was heard to be mumbling something about the cost of a Costello fuel injection system)

Paul Kile

So build another V8 to play with! Thats what I did, (although
my factory '76 V8 could hardly be called standard.)
You have to fit a balance pipe between the two banks though
or the car sounds like an off-road monster truck!
Next Summer ,if I still have the roadster, I shall take it to SS
exhausts and have them duplicate the MTP system in stainless.
Vey interesting article in MG World comparing the Weber aka
Edelbrock aka Carter with the 4150 Holley.
I have just bought a 600cfm 4160, to which Im adding a secondary metering
block. Ive already removed the choke mechanism, including
the butterfly and fitted a quick change accelerator pump housing.
Im going to do some comparisons on Sigmas rolling road between
the existing 600 double pumper and the new vaccuum secondary unit.
The dp gives 140 bhp at the wheels on the first two barrels
and then goes up to 215-220 with all four. Sigma think it would be better
to get all four barrels going earlier. Interesting.
BobP to Paul

Bob P.- Sounds like fun! Did Holley make a mechanical linkage to open the secondaries, or are you stuck with the vacuum system? I admit I haven't played with Holley carbs much, I'm a lot more familiar with SUs from all my British stuff, although I had a pretty neat small Carter AFB on my '65 Barracuda with the Hi-Po 273 V-8.

I would consider building an MG V-8 from scratch, but my finances can only handle one major project at a time. Then there is the Better Half, whose first reaction will be "Why do you need another MG V-8, you've already got one! I think I would have more luck getting her to agree on the Studebaker Avanti project I've always talked about.

But that's a whole 'nuther story....

Paul K.
Paul K. to Bob P.

Now I'm back from my vacation in Greece I didn't see any MG's there thow some Austin's that's all.
The balance pipe you people are talking about does it add anything in performance or is it strictly a sound issue ?

Jhonny Sokura

The balance tube, or coss-over pipe, improves torque and gives more usefull RPM range on horsepower. It also removes some of the crackle from the exhaust note.

HTH, George B.
George B. Wildomar

My car ,which initially had a V8 developments twin system married
up to RV8 manifolds without the benefit of a balance pipe,
sounded diabolicaly lumpy and uneven.


Bob, so does my big-cam '68 Camaro and my Harley. I LIKE IT! Both have a balance or crossover pipe, by the way.
Carl in TN

I dont suppose you hillbillies in the Ozarks have to fit mufflers! Or is it the cam. Once I had fitted a balance pipe and better silencers the cars exhaust note still echoed off the stone walls in Merry Old England, but it was a lot more pleasant on long journies. With only 215 ci as against the 350 or so you have in your Camaro you need to make sure you get torque as well as burble!
Bobp to Carl

Any rules for how the balance/crossover pipe should be
fitted ?

Jhonny Sokura

Don't have it welded in permanly. Have it joined by flanges. This will make any future under car maintenance/repair work easier to accomplish . Barrie E
Barrie Egerton Sydney

In order to contribute in as objective a manner as possible, given the highly subjective comment which has been made, I have considered the two parts to the ongoing discussion: -

Balance Pipe

During our extensive period of development we investigated other available twin systems. We did this through business contacts, advertisers in kit car magazines as well as asking other V8 specialists to seek their advice. We asked a number of questions: -

1. Were there any other twin systems available
2. Do they have a balance pipe or not
3. What are the benefits of a balance pipe
4. What are the downsides of running without a balance pipe

In summary our research showed:-

1. There were other systems available
2. Some of the other systems available were balanced, some were not.
3. We can confirm that the following benefits quoted in previous emails are correct: -

 Improved low down torque. This is true, however the accompanying observations were that with an engine like the V8 which has a naturally massive torque characteristic, the torque difference that the driver will 'feel' with a balance pipe is negligible.

 RPI recently observed "With reference to the balance pipe, it would have to be fitted so low down that it wouldn't be effective enough"

 A 'smoother', less 'lumpy' sound (discussed later).

Extra power (BHP) has been quoted, however this was not corroborated during our research. Power is the result of many factors but importantly also the ability of the system to breathe freely, this is not measurably improved by introducing a balance pipe.

4. If a balance pipe is fitted it adversely affects: -

 Longevity of the systems. By introducing a T-piece into the downpipes, it means more parts, which can be damaged in use and allow leaks to develop.

 Potentially lowers the ground clearance depending where the balance pipe is fitted (the lower down the system it is fitted the less effective it is).

 Increases production costs, which would increase price to our customers.

 Would take the 'edge' off the exhaust note, especially on the four box systems (See Sound).

I recall during my degree years, what seems like a lifetime ago, ago pogo'ing to the sounds of the Jam, the Sex Pistols, and many more. These Pop groups were described by my Mother and Father as diabolical. However their opinion has got to be questioned as they had previously described the Beatles and the Rolling stones in a similar fashion to my elder brothers and sisters. 'Some things never change'.

The Twin system Bob referred to (Turbo Tourer) is by far the loudest system we have developed and all our customers are advised of this fact. They are also advised that as the systems are modular, their sound can very easily be changed, either 'up' or 'down' by swapping pipes for boxes or vice versa.

I have listened to balanced and unbalanced Twin Systems and again my own preference is for that 'lumpier' unbalanced note. There is no mistaking a V8 on Twin Unbalanced Open Pipes.

My favorite quote from Len, one of the Edinburgh MGOC members was "I could follow that forever", needless to say, he and many other club members were very enthusiastic about the loudest of our systems. It was my own personal favorite for a while, but I have since gone to the opposite end of the scale as I have now swapped the center pipes for center boxes, resulting in the 'Tourer' system. Perhaps it's due to my hitting 40!!!

I have concluded that the appeal of a particular sound can be influenced by many factors, from age to cultural influences.

When all factors were considered our development team concluded to stick with unbalanced twin systems and offer a wide range of sounds and volumes.

Having been selling systems for many years now, I am very pleased to say that of all our customers, the only negative feedback we have ever received has been from Bob. It's just a pity that he is such an avid advocate of the 'balance pipe' and highly prolific on the web! But as I said in Classic Cars a while ago, "that’s showbusiness"!!!

For pictures and feedback from some of our other customers cars and Twin System installations, see.

Most importantly… Keep enjoying those V8's as there isn't anything else like them.

Kind regards to all

Dave Lord Proprietor V8 Developments

Dave Lord

Paul Kile
I have a 69 GT with a professionally installed 289 Ford v8. I live in Sacramento, and would like to see your car. Email me if that is possible, maybe you can give me some tips on my car.
Steven Taylor

I have been told that you can't just put the balance tube anywhere you want. I believe that the way to find out where the balance pipe needs to go would be:
Mount the dual system
Get some cheap spray paint and put a few stripes down each tube
Start the engine and see where the paint burns off
This would be the point where you cut the tube to put the T in.
Apparently this is the point where pressure builds up.
Maybe someone can tell me if this idea is fact or fiction.
Michael Hartwig

What Dave fails to mention in his comment is that the action of the balance tube is different depending on whether you are using 4-2-1 headers (interference type) or 4-1 collector type. The addition of a balance tube on collector header V8, which most are, gives some measure of interference between the two banks and thus improved torque. The place to fit it is right behind the pipes leaving the collectors, (assuming you are using RV8 manifolds) using an H-Piece where the uprights are of larger diameter than the exhaust system so that they sleeve the collector to the rear sections. The system I bought from Dave was for a non RV8 set-up which I knew and didnt work out. What I didnt like was that it was made up of a number of short lengths of pipe and the size of the silencers. Perhaps I am more exacting in my requirements Dave plus of course knowing a little about exhaust sytems. I therefore went to MTP who has made many good systems for a variety of my cars over the years bearing in mind advice from Dave Franklin (V8 and Lola 5000 racer ) and had him make me a system to suit the RV8 collector type headers, complete with balance pipe and larger rear silencers. I was delighted with result. However in my opinion ithas all been a waste of time! My V8GT with a 3.9 giving 215 bhp at the wheels seems to manage very well with a single 2&1/2 inch system! Just by the way, I have had an excellent stainless exhaust system made for my wifes Maestro at SS Exhausts in Cullompton. Mick at Torque Techniques in Gillingham (Dorset) will be making the system for my M16 Magnette together with thw twin SU inlet manifold.
So save your money guys and use the RV8 Headers with a single big system!
robert pulleyblank

This thread was discussed between 15/09/1999 and 27/10/1999

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