Club 80-90 Forums

Steve from Gasure (lovely bloke) mentioned in passing that he thought my van seemed down on power and that a possible reason for this was that the exhaust bores seem quite small for my engine (1984 1.9 petrol DG). It's an aftermarket stainless steel exhaust that the previous owner fitted. I've not measured them on my van properly yet, but what is the standard/recommended exhaust bore size for my engine?

Thanks

Iain

Haven't a clue....however, I wouldn't imagine the restriction (if there is one) lies with the headers (the pipes coming from the heads), rather, if there is an issue, it will be into and out of the silencer. Either collapsed silencer internals or the physical size of the entry or exit to the silencer (tail pipe like a pea shooter)

Can you feel a variation in exhaust blow (individual pulses) as the engine goes through it's firing order. OR are you feeling a constant 'blow' which may signify restriction.

Martin

Hi Martin,

At idle, I can't really feel any pulses or anything like that. It does rumble a little bit towards (what I think is) the end of the sequence. The exhaust tailpipe was just welded as part of it's MOT, so it may well have been blowing due to that. Just to explain, this isn't something I would have noticed myself. This is the only T25 I've driven and although I thought it was slow and thirsty compared to a more modern car, I had no frame of reference for how the DG engine should perform.

Steve (Gasure) told me he thought it seemed a bit strangled but couldn't explain why without some serious investigating. The exhaust was one possible reason he suggested for it. Also, he told me that the timing was 'very advanced' for reasons unknown to him (or me). To make it even more fun, the previous owner put a new pulley wheel on it that doesn't have the timing marks on it. My very limited understanding of this suggests that setting the timing is more difficult now as a result.

Iain

Who made the exhaust? pics?

I'll post some pics when I get home.

Not sure on the manufacture of this particular exhaust, however I have never seen stainless tubes at this small a diameter on a T25 before, they are roughly only an inch diameter, hence the suspect strangulation, however I did say that some more investigation should be done before the system is junked.

Ha!

I'm a bit embarrassed that I didn't realise Steve was a founder member of this site.

D'oh!

Bore size is only a part of it, 1 inch is about right for the early systems from each port. more important is the ideal length, for these engines 2mtrs from port to exit hence the spaghetti system fitted to the latter engines or the nice expansion box fitted to the earlier engines.

I beg to differ on this one, I've just measured a standard early bore and its 38-40mm not 25mm and I only mentioned it could be strangling the engine, like I said before it needs investigating, I know when we port the heads on the CU motor and get Richard from Turbo Thomas to build us "j" tubes to match we get a very big variance in power from the stock.

Easy chaps.

I don't want any arguments to start on my account, I meant no disrespect to anyone and was only querying something I was told about.

The upshot of this is, as it was in the beginning, that my engine does need a proper looking at to find why it's down on power. Investigating/changing the exhaust was something I thought I might do myself, but will have the van checked out properly in case it's something else (hopefully something cheaper than a new exhaust )