Volvo Amazon Exhaust system

[grumpydad]

Hi
I must ask have you done much classic rallying
i have done quite a bit over the last 25 years
for Hero and HRCR MSA events
you dont want a noise exhaust cos if you do have one
your navigator will have to shout all the timeit becomes very tiring
especially on things like LeJog

[Classic rally]

I have the stock SU carburetors. As you have said. The side draft carbs will sound a lot nicer. I am planning on fitting some Webers to the car to get that nice induction noise.

Also, I have found a custom exhaust place near me who have said that the mild steel tubing does not help with the sound as mild steel absorbs a lot of the sound. They have said that the stainless steel piping will sound better and they will make a small round muffler at the rear. With 2 inch or 2 1/4 inch piping there will be no droning noise. But first I will need to sort out my exhaust manifold. I will start a new post with regards to exhaust manifold to see what others have done as there is not much info online.

Plan is to switch to webers, change exhaust manifold to a 4 2 1 setup and custom stainless exhaust with one small muffler at the back. This muffler will be interchangeable so I can fit a mild muffler for Hero events etc.

[grumpydad]

HI
exhaust manifold

This one is a copy of the volvo R sports
https://www.skandix.de/en/spare-part...s-4-1/1007529/

this one is a copy of the Rudspeed one
https://vp-autoparts.com/en/artiklar...2-b18-b20.html

[Rustinmotion]

Originally Posted by grumpydad

HI
exhaust manifold

This one is a copy of the volvo R sports
https://www.skandix.de/en/spare-part...s-4-1/1007529/

this one is a copy of the Rudspeed one
https://vp-autoparts.com/en/artiklar...2-b18-b20.html

In theory 2nd option should give more torque than 1st
I changed a cast twin down pipe manifold to the 1st option and to be honest I can’t say I noticed any difference, I’d think a new profile cam would be needed to get the best out of any extractor manifolds but don’t expect huge gains

[Derek UK]

The cast twin outlet manifold is fine for states of tune up to about 145bhp. That's about the limit for SU's and the next step would be Webers. Component selection and specs get a bit more complex at that point.
As you say. 4 into 1 is for top end power and 4-2-1 for torque.

[Classic rally]

I am looking at getting the 4-2-1 exhaust manifold as you have all said it is better for low down and mid range torque. I am not sure what the difference is with the different ones though. Brook house have this one that is designed like R-sport headers. What are they referring to when they say R-sport?

https://www.classicvolvoparts.co.uk/part.asp?
pID=9125&carID=3&cID=61&scID=315&page=FOUR+BRANCH+ EXHAUST+MANIFOLD+%284%2D2%2D1%29%2E+DESIGNED+LIKE+ ORIGINAL+VOLVO+R%2DSPORT+HEADER%2E+

I have been told that I should get it ceramic coated.

or there is this one which is stainless steel which is not available now so not sure if it will be soon.
https://www.classicswede.org.uk/deta..._13110638.aspx

Alternatively I could get one custom made out of stainless steel.

I keep seeing different figures for the HP rating for the 123gt. I think it has 115 hp so if I convert to webers it should give at least 15 HP increase no?

So I am planning on sticking with 2 inch piping for the exhaust or going to
2 1/4 inch though some of the exhaust manifolds are 2.5 inch.

[Rustinmotion]

Originally Posted by Classic rally

I am looking at getting the 4-2-1 exhaust manifold as you have all said it is better for low down and mid range torque. I am not sure what the difference is with the different ones though. Brook house have this one that is designed like R-sport headers. What are they referring to when they say R-sport?

https://www.classicvolvoparts.co.uk/part.asp?
pID=9125&carID=3&cID=61&scID=315&page=FOUR+BRANCH+ EXHAUST+MANIFOLD+%284%2D2%2D1%29%2E+DESIGNED+LIKE+ ORIGINAL+VOLVO+R%2DSPORT+HEADER%2E+

I have been told that I should get it ceramic coated.

or there is this one which is stainless steel which is not available now so not sure if it will be soon.
https://www.classicswede.org.uk/deta..._13110638.aspx

Alternatively I could get one custom made out of stainless steel.

I keep seeing different figures for the HP rating for the 123gt. I think it has 115 hp so if I convert to webers it should give at least 15 HP increase no?

So I am planning on sticking with 2 inch piping for the exhaust or going to
2 1/4 inch though some of the exhaust manifolds are 2.5 inch.

Ceramic is to keep the heat in you get two benefits
Keeps under bonnet temps lower which is good if your using open carbs and two hotter gas by volume is larger so it has to move faster to clear the same volume, faster gasses give better extraction at valve overlap which is why headers are
more useful with hotter cams
I just wrapped mine with heat wrap
One thing I had issues with dynamo hitting cyl 1 down pipe so had to convert to alternator which is no bad thing

[Classic rally]

This is a very interesting articles on stainless vs mild steel and ceramic coating etc.

https://burnsstainless.com/blogs/art...rounding%20air.

It would probably be better to have a custom exhaust manifold made out of good quality stainless steel and not ceramic coat the mild steel manifold. For the cost of buying a mild steel manifold and having it ceramic coated would probably cost more or the same as having an exhaust manifold made out of stainless.

[Burdekin]

Originally Posted by Classic rally

I am looking at getting the 4-2-1 exhaust manifold as you have all said it is better for low down and mid range torque. I am not sure what the difference is with the different ones though. Brook house have this one that is designed like R-sport headers. What are they referring to when they say R-sport?

https://www.classicvolvoparts.co.uk/part.asp?
pID=9125&carID=3&cID=61&scID=315&page=FOUR+BRANCH+ EXHAUST+MANIFOLD+%284%2D2%2D1%29%2E+DESIGNED+LIKE+ ORIGINAL+VOLVO+R%2DSPORT+HEADER%2E+

I have been told that I should get it ceramic coated.

or there is this one which is stainless steel which is not available now so not sure if it will be soon.
https://www.classicswede.org.uk/deta..._13110638.aspx

Alternatively I could get one custom made out of stainless steel.

I keep seeing different figures for the HP rating for the 123gt. I think it has 115 hp so if I convert to webers it should give at least 15 HP increase no?

So I am planning on sticking with 2 inch piping for the exhaust or going to
2 1/4 inch though some of the exhaust manifolds are 2.5 inch.

Twin SUs can support 115hp easily supplying enough air and fuel so doubt changing to Webers will give you any increased HP if the SUs are setup properly. Have you tuned the carbs with a rolling road or wideband O2 sensor, you might be able to richen the mix and you can get them flowing better with work.

Go the custom route. There’s a guy here that makes beautiful stainless exhausts, there will be someone near you I’d imagine.

[Classic rally]

Originally Posted by Burdekin

Twin SUs can support 115hp easily supplying enough air and fuel so doubt changing to Webers will give you any increased HP if the SUs are setup properly. Have you tuned the carbs with a rolling road or wideband O2 sensor, you might be able to richen the mix and you can get them flowing better with work.

Go the custom route. There’s a guy here that makes beautiful stainless exhausts, there will be someone near you I’d imagine.

The main interest in the webers apart from the the possible increase in power is the sound. For me one of the most enjoyable parts of driving a classic is the sound and from experience with the datsun 280z and 240z I had with weber, stainless exhaust manifold and stainless exhaust was the difference in sound from stock setup. Of course we are talking about different engines with the volvo but the Tasmin volvo amazon with webers and exhaust etc sounds amazing. This is what I plan to get close to.

I have found a couple of fabricators that specialise in stainless exhaust manifold fabrication. I'll check prices tomorrow.