VX Exhaust Questions

[Pope1]

Can anyone tell me what the differences are between a VX exhaust and a N/A one please? In particular, is there any difference in the design and flow rate of of the back box?

[andybeta]

Chris,
Rather than risk this question going 'bump' I thought I better start a response. Are there any differences in the OE systems? I would have thought the VX system would need to be as free flowing as possible by having straight through boxes to reduce back pressure for the s'charger. Not having an OE system for either variant to put a broom handle through it is difficult to say. But Chris Bastow might know.

Don Pembelton of Huthwaite could do you a nice back and transverse box with connecting pipework in 2.5 inch stainless steel if you fancy. I've seen one he did for a VX Coupe that looked and sounded very nice. If you wanted just the tail box I shouldn't imagine it would be too pricey.

Not sure whether the normally aspirated engines have systems with baffled boxes or not. Maybe the back box was baffled but then Lancia would have had increased production costs if it fitted different varieties of exhaust to the same model. I would have said each model Coupe, HPE, saloon, spider would have had a generic exhaust for the model with varying connecting pipework. The transverse and middle ones were straight through as far as I know.

Probably this hasn't been of much help. But either way I would be looking at a straight through box for your VX. Are you looking at fitting a tail box from a normally aspirated engine then?

Andybeta

[Pope1]

Hi Andy,
Thanks for the response. The official Lancia word was that the VX had a modified exhaust but no mention was made of what the mods were. Like you, I find it difficult to believe that they were significant.

My car currently has centre and rear sections that came from my spare car. I think the rear one might be an Ansa one (rather than a genuine VX) so I'm wondering whether that might be blunting performance a bit.

I was thinking of replacing the back box with a custom one or, if it's not going to cost an arm and a leg, replacing the small mid one with a straight 2.5" pipe and having custom transverse and rear boxes. Not as effective as doing everything from the engine back but not as expensive either.

I believe that Don Pembelton 's system avoids the hoop to the rear box. Do you know whether he takes the pipe over the rear transverse links to achieve that or does he route it somewhere else?

[DJ]

FWIW, the Volumex tech data document (http://lancisti.net/index.php?ind=downloads&op=entry_view&iden=17) in the Beta downloads section states the following.


Engine exhaust system exhaust piping (front, intermediate, rear sections) of increased diameter - silencer of new design.

[Pope1]

Thanks DJ. I'd missed that bit in the documentation.

[andybeta]

If yours is Ansa then it is probably a straight through variety and will not be adding to back pressure as would a baffled box. Put something through it - wire coat hanger, gardening cane. If straight through it will literally go straight through. If baffled it won't.

He can do what ever you want as he custom builds. He did have an OE Coupe VX system as a pattern that he had acquired. On mine (HPE - longer rear floor pan) he took the traditional route over the transverse cross member as both he and I felt there simply wasn't anywhere else for the pipe to go without dramatically reducing ground clearance or interfering with the suspension arms. If I remember he very slightly flattened/ovalled the pipe at the top of the bend going over the cross member as space is tight especially with 2.5 inch pipework, but then again he might have had enough space. I can't remember to be honest. He did a pretty good job though. He made the tail silencer slightly longer as there was some available space to be had especially as I no longer have the middle (first) silencer, just the transverse and rear boxes.

Hope this helps.

Andybeta

[Pope1]

Thanks Andy. If I go ahead, I'll probably get it done locally at a Powerflow place that has done good work for me before. They fabricated a completely new 3" over-axle pipe for the Golf amonst other things when I ran out of patience with the one I had before. It's been perfect for over a year now.

It takes some work to get those suspension arms horizontal let alone to go above that so there might be room to run a pipe above them but I don't think I have the balls to risk it myself. I'll probably stick with the standard layout for the pipe.

[Pope1]

Checked this evening and the rear box is straight through. Does that mean that there is little to be gained (except noise) by tinkering with the boxes and pipes alone guys?

[chrisc]

Checked this evening and the rear box is straight through. Does that mean that there is little to be gained (except noise) by tinkering with the boxes and pipes alone guys?

Not much to go on by my old VX had the middle silencer replaced with a straight through one. It was louder than my current one but didnt 'go' noticeably better.

[andybeta]

Checked this evening and the rear box is straight through. Does that mean that there is little to be gained (except noise) by tinkering with the boxes and pipes alone guys?

Chris,

Not really, the short answer.

If you've got straight through silencers along the length of the system then back pressure is going to be lower than if any baffled boxes are fitted. You are pretty much there. You might achieve slightly less with a 2.5 inch system as opposed to a standard bore system but tbh the cost is probably prohibtive for the actual gain you would achieve if any. The larger bore exhaust may well be noisier.

The next "improvement" would be a 4-2-1 or 4-1 manifold which would only be worth while dependent on the set up of your engine, carburation and the type of use you put it too. If I remember you have the 40DCNF with std inlet cam and exhaust manifold? What sort of power improvement were you anticipating? A more free flowing exhaust and manifold will make the engine more responsive and easy to rev although there might as I understand be sacrifices between torque or bhp power between 4-1 or 4-2-1 mainfolds at the upper rev limits. Think of all that fuel being burned when you red line it!!!! £££££££. I would suggest a good rolling road to sort out how your car is performing or not performing at present and then go from there.

Dave Gregory's (Spartan) has his nice black VX Coupe for sale which has a GC engine and a full straight through stainless system with 4-1 exhaust manifold. Just something to consider.

Andybeta

[DJ]

Dave Gregory's (Spartan) has his nice black VX Coupe for sale which has a GC engine and a full straight through stainless system with 4-1 exhaust manifold. Just something to consider.


Oooohh! Stop teasing me, Andy... ;)

[Pope1]

Chris - your experience appears to confirm my suspicions about what might happen.

Andy - I have no idea whether the other boxes are straight through or not. I only got to wondering about the exhaust as I'm still trying to track down the horses that went missing when my car was laid up and the rear section of the exhaust was one of the few things that I changed. The last RR session produced figures of 135/160 (little better than standard) but also revealed some carb problems that have since been resolved plus a few more I found and sorted last week. It feels like it's doing better than that now but is still not where it was before in terms of power. I'm just trying to get as many things sorted as possible withourt spending loads so that I can enjoy what little time remains before I'm forced to part with it. I reckon both my cars are on borrowed time due to increasing motoring costs and I have begun to seriously consider alternatives. Another RR session is due soon (following a service this week-end) so I'll probably just work with what I have fitted now and see what results I get this time round.

[andybeta]

Yes indeed the cost of motoring is now prohibitive certainly even on a modest budget in the UK. And still the oil price shows no signs of dropping or the gov. reducing it's take. I wish we paid as little for our fuel as they do in the US. But the Beta is still ok for doing a couple of thousand summer miles a year if it even does that. Last year mine travelled 1.8 miles, under it's own steam I hasten to add, to the MOT station and back.

Sorry I can't be much more help on the exhaust front. Difficult not having an OE system to check on spec really.

DJ - yes DG's black VX Coupe is tempting. I'm sure he could ship it if you were very tempted.

Good to read you're recovering some of the horses you think have escaped since you had your major engine work done.

I'm trying to get mine mobile for the MITCAR meet in mid August in the Northants area.
But as always there are other competing priorities that could scupper that. It would be nice to see a few Betas there. I'll try and make it in a Beta or failing that Fiat.

Anyway hope the good weather this weekend has enabled you to get more done with the car.

Andybeta

[A1.6HPE]

Hello Chris,
The one thing I know about the difference between VX and N/A exhaust systems is that the manifold studs are 9mm instead of 8mm. If you shear a 9mm stud that is bad news as such things only existed in Chivasso in 1982 - 1984.
Chris Bastow told me about the lack of studs. The shape and style of the two manifolds are the same, I think that the pipe holes are the same size btw.

Its been a while, best regards, Leo

[Pope1]

Andy - good luck getting yours ready. It will be good to have it on the road again.

Leo - yes it's been a while. Hope you're well and thanks as always for the info.