Exhaust bore size

[highlander]

Hello,

I phoned my local Powerflow dealer with the intention of booking my Coupe in to get the stainless exhaust from my old 1.8 saloon fitted. But the guy there was wary - he said the bore size between the old car and the new car may be too great. He also said the route the exhaust takes, and the positions for the hangers (etc) may be too different.

He said I could take the car up there and ask him to have a look - will be doing that at the start of next month - but I was hoping maybe someone here might know the bore sizes of the 1.8 and 2.2 exhausts, or be able to tell me if they would be compatible.

Much as I love the rasp of a stainless exhaust, I don't know if I can afford to get a new one made up at the moment - I was kinda counting on this one being compatible with little or no modification.

As always, any help is greatly appreciated.

Cheers
Graeme

[Welly]

I don't know the bore size you need but I do know it is critical for the engine to develop torque. I had a full stainless 'thing' made my Honda Integra and they cheerfully increased the bore size to approx 50mm (from about 40mm) and it ruined low-end torque - it was really flat the correct bore size (which is designed with the original engine set up) is critical to effect something called 'exhaust gas scavenging' something which normally aspirated engines require. Of course I learnt all this after the event

I had to revert to an OE replacement at considerable cost and embarrassment in the end, in fact my wife hasn't referred to this episode in my life for quite some time. Perhaps my calamities have a shelf life? being as it is now some 6 years old

You might also need to bear in mind the 2.2 will be louder than the 1.8 (bigger bangs) and could sound too loud?

[highlander]

I'd been planning on asking them to change the exhaust note anyway - it is quite noisy at about 3,000 RPM, which is less than ideal for long-range motorway driving.

Ideally, it needs to be a low burble at idle and quite quiet at cruising speeds so it's not too loud on the motorway, but it should still give a good loud snarl when I put the foot down.

[plod]

I do know the position of the hangers will be the same, so not a problem there as I have a V6 Powerflow from a "coupe" sitting on my HDi saloon


Mine is quite subtle, and there is a nice roar from 80mph onwards - allegedly

[steve_earwig]

Exhaust bore?

I know it doesn't give sizes on Service Box but what about clamps?

XU7J4P/B/P4 (don't know which yours was) - 61mm
EW12J4 - 74,5

Hmm, how much difference can half an inch make?

AFAICBR one of the hangers changed but I guess you won't know until you get it up in the air. I guess if it fits without too much messing about you could see how it goes and if it slows you down you can flog it on when you have the cash to replace it.

[plod]

AFAICBR one of the hangers changed but I guess you won't know until you get it up in the air. I guess if it fits without too much messing about you could see how it goes and if it slows you down you can flog it on when you have the cash to replace it.

When fitting mine we had to turn one of the brackets for the back box round 180deg, otherwise all the other hangers lined up

[highlander]

Exhaust bore?

Me? How dare you!

Hmm, how much difference can half an inch make?

Quite a lot, potentially; Welly mentioned moving from a 40mm to 50mm bore exhaust, and the power just disappeared. I would hate to strangle the engine with exhaust gases.

I guess I'll just need to go see them and see what they have to say about it - maybe they could trade the components in for a discount for a complete new system. Fingers crossed.

Does anyone have access to Autodata? Is that likely to have the information I'm looking for?

[omega]

i bet the bore is diffrent
i have stripped a few 406 d8s and i can tell you that the bore is diffrent between petrol and diesel.
have a look on ebay as that might give a clue.

[highlander]

Thread necromancy here...

Took the old exhaust up to see the guy who installed it, and had the car up on the ramp. Immediately he spotted there was a massive difference in the size of the piping.

The pipe that comes out of the cat and goes into the first silencer box enters that silencer box quite far to one side (in comparison to that of the old PowerFlow). On the old PowerFlow that silencer box is also markedly smaller. Basically, the old exhaust wouldn't physically fit, and even if it did, the diameter of the OEM pipe vs. the diameter of the old PowerFlow pipe would mean the engine would be strangled.

He did say we could maybe use the back box and the piping, and connect it to the rear of the car's original middle silencer, but given the diameter of the piping, he reckoned at higher revs, the performance would be reduced.

However, while it was up on the ramp, we saw that there are several spots where the exhaust is leaking quite badly.

I've booked the car in for Tuesday afternoon to get a brand new PowerFlow exhaust system custom-designed and fitted. Should look, sound, and perform quite nicely; looking forward to it (if not the bill).

This also means I have a PowerFlow exhaust system available for sale to anyone nearby (face it: it won't fit in an envelope!). Will be suitable for a 1.8 litre, or maybe a 2.0 litre (unsure). Was on my old car for about a year. Offers pls if you're interested!

[highlander]

Update: I am one happy chappy; the Coupe now sports a lovely new cat-back stainless system

Photos to follow