Perkins engine exhaust dia

flyingbanana · Nov 13, 2020

I've been doing odd jobs on my 2a 109
And it looks like the exhaust is a standard Diesel one apart from join to perkins manifold,
Do you think It should have a bigger bore pipe to allow for better running and what diameter would be better suited for my engine

Stretch · Nov 13, 2020

flyingbanana said:
I've been doing odd jobs on my 2a 109
And it looks like the exhaust is a standard Diesel one apart from join to perkins manifold,
Do you think It should have a bigger bore pipe to allow for better running and what diameter would be better suited for my engine

Well you could make some calculations such as those here =>

https://www.exhaustvideos.com/faq/how-to-calculate-muffler-size-pipe-diameter/

(estimations as a function of displacement)

But if the manifold on the Perkins is bigger than the Land Rover exhaust I'd just match the diameter if you want something that is kinda intended for the Pertkins

On the whole a slightly smaller diamter isn't going to cause trouble unless you constantly drive around at max rpm - slower rpm == less air flow

With a bigger pipe you are more likely to make more noise though so perhaps that's something to consider (depending on your intention)

tottot · Nov 13, 2020

Hi, Is the diameter of the Perkins manifold exit much larger than the standard 109 exhaust ? If so an increase in the exhaust pipe size may be beneficial up to the size of the perky manifold but no more.
If you go down this rout a complete system for early 110 may do the job. Handy if you can stick to as many standard sections as you can even if mounting points have to be changed.

Turboman · Nov 13, 2020

tottot said:
Hi, Is the diameter of the Perkins manifold exit much larger than the standard 109 exhaust ? If so an increase in the exhaust pipe size may be beneficial up to the size of the perky manifold but no more.
If you go down this rout a complete system for early 110 may do the job. Handy if you can stick to as many standard sections as you can even if mounting points have to be changed.

Exhaust manifold on a 4/203 is pretty small internal diameter, as are the outlet ports on the head.
I don't have one here to measure, but thinking no bigger than 1 1/4 inch.

Turboman · Nov 13, 2020

flyingbanana said:
I've been doing odd jobs on my 2a 109
And it looks like the exhaust is a standard Diesel one apart from join to perkins manifold,
Do you think It should have a bigger bore pipe to allow for better running and what diameter would be better suited for my engine

Any Landrover exhaust is fine for that.

tottot · Nov 13, 2020

Given what Turboman say's you may as well stick with what you have.

rob1miles · Nov 13, 2020

Just doing this now. Perkins manifold is about 1 1/4 and opens out to be about 1/8" bigger than the std series exhaust. I recently made up an adaptor to allow me to fit the std exhaust to the Perkins manifold, its about 5" long. It works fine and I bleive I'm getting the full 63 hp out of my Perkins, it will shift the loaded LWB, with camper roof and loaded roof rack up to 60+. BUT, I think there is a problem with the exhaust, my engine temp rises very sharply above 2000 revs (ie 60mph) and I think the manifold is the culpret, it has 2 right angle bends plus another to the exhaust. Some of the conversions had a free flow manifold, I can't find one but I have a picture and I'm looking to buy the bends off e-bay in mild steel and weld one up. Its about £25 in bits. This is what I'm aiming for, it fits to the std LR down pipe.

Turboman · Nov 13, 2020

rob1miles said:
Just doing this now. Perkins manifold is about 1 1/4 and opens out to be about 1/8" bigger than the std series exhaust. I recently made up an adaptor to allow me to fit the std exhaust to the Perkins manifold, its about 5" long. It works fine and I bleive I'm getting the full 63 hp out of my Perkins, it will shift the loaded LWB, with camper roof and loaded roof rack up to 60+. BUT, I think there is a problem with the exhaust, my engine temp rises very sharply above 2000 revs (ie 60mph) and I think the manifold is the culpret, it has 2 right angle bends plus another to the exhaust. Some of the conversions had a free flow manifold, I can't find one but I have a picture and I'm looking to buy the bends off e-bay in mild steel and weld one up. Its about £25 in bits. This is what I'm aiming for, it fits to the std LR down pipe.
View attachment 223153

Possible that the manifold is causing overheating, but I would be doubtful. What you have looks a very nice manifold compared to most I have seen on those.

What radiator do you have? My Perkins engined Series had 6 cylinder rads, which were a large capacity of coolant.
Neither of them ever overheated, and in both cases, the manifold was just straight tubes welded up at right angles.

rob1miles · Nov 13, 2020

No that's what I DON'T have. What I have the the horrible one with the 90 deg mitred bends. I think it sets up a standing shockwave between the ports. That's why I like that design in the pic and the only way to bottom this out is to make one. I've tried searching and no joy, the one in the pic was a sold item on e-bay. Ideal lock down project me thinks.
Mine looks like this:

but there are better ones about: But I think the only way to get one is make it.

Turboman · Nov 13, 2020

rob1miles said:
No that's what I DON'T have. What I have the the horrible one with the 90 deg mitred bends. I think it sets up a standing shockwave between the ports. That's why I like that design in the pic and the only way to bottom this out is to make one. I've tried searching and no joy, the one in the pic was a sold item on e-bay. Ideal lock down project me thinks.
Mine looks like this:
View attachment 223159

but there are better ones about: But I think the only way to get one is make it.
View attachment 223160

That is pretty much exactly what I had on both of mine, and more or less similar to the manifolds on the several Perkins engined tractors I have had. Never caused any problem at all, that sort of engine is not that bothered about exhausts.

Have you taken the thermostat out, and driven around to see if it overheats like that?

lynall · Nov 13, 2020

I know nowt about the perkins, but when I fitted my tdi I used the original exhaust system, and tbh it ran fine, then I made up a complete new exhaust system and it revved faster and cleaner.
Few years later, and it needs a new one again, this time its going to be stainless.

Turboman · Nov 13, 2020

lynall said:
I know nowt about the perkins, but when I fitted my tdi I used the original exhaust system, and tbh it ran fine, then I made up a complete new exhaust system and it revved faster and cleaner.
Few years later, and it needs a new one again, this time its going to be stainless.

I am sure that would be right, I know people who have improved Tdi just by removing the rear silencer.

But a 4/203 is a different animal. Not turbocharged, and revs 2500 rpm less, or thereabouts.

rob1miles · Nov 13, 2020

Just looking at the exhaust the most restricitive part is the tail pipe, its smaller than the rest of the system, so looking for a back box with a bigger tail pipe could be an idea.

adrian hogg · Dec 20, 2020

Back in the murky distant past we used to get lots of owners bringing in landrovers asking us to check their none standard diesel engines as they were disappointed with performance following fitment of perkins/isuzu.toyota/daihatsu etc. invariably we would find the standard "pea-shooter" series exhaust would not let the bigger/more powerful engine breath. Have a look here Anglo Agriparts I Tractor Parts UK I Tractor Spares UK (anglo-agriparts.com) for perkins manifolds/flanges/gaskets etc you may find they are so cheap its not worth making things. Massey 165 and 65 was fitted with 4/203

Perkins engine exhaust dia

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