Surprise performance exhaust found on my donor HPE VX!

[VXdeMayo]

dear all,
I wonder if you can help me with a query regarding the above. Namely I was grubbing around under my donor HPE VX (1985), with the intention of taking a look at the stainless exhaust system that the previous owner had had fitted. I was trying to assess the possibility of refitting it to my very good HPE VX (1983), and on taking the back box down and cleaned it revealed the name POWERFLOW. I have now taken the long centre section and the 4-2-1 manifold off (without shearing any bolts), and have cleaned all.
What I have is a decent looking 4-2-1 manifold, butting with a sprung flexible joint onto the long centre section which has a straight through looking "cherry bomb or bullet style" silencer half way along. just behind this is another bigger straight through standard shape box. The rear section then has a final straight through standard box before fininishing soon after. the final and main bore diameter is 48mm approx ID. (42mm on standard VX). All three silencers are chromed and look good.
Can anyone tell me what extra BHP this system is likely to give? I remember the previous owner telling me that he spent quite a tidy sum on this before selling this car on to me.
All the best,
Chas (very chuffed), VXdeMAYO.

[MattNoVAT]

Chas,

Sounds like you've had a good result there.  Maybe contact PowerFlow to see what they say?

[rossocorsa]

I can't imagine that this will give massive gains as standard but certainly something and no doubt the drive will feel a lot better, if you plan to tune the engine this will give you a big head start although to be perfect I understand that a 4 into 1 works better with forced induction than a 4-2-1, having said that I will be using a 4-2-1 on my car because I have one and budget is tight. Certainly looks like you've got a good system there.  

some pictures of the system would be nice by the way!

Alan

[VXdeMayo]

Dear All,
After your requests for some photos, I have cleaned up the stainless system with a bit of elbow grease, and wire brushed the mild steel 4-2-1 manifold prior to spraying it with 800 degree c High temp paint. To say it has come up a treat is an understatement!
Perhaps one of you might enlighten me as to the possible BHP gains or benifits from fitting this set of pipes?
All the best,
Chas,
(VXdeMAYO).

[HFStuart]

The manifold looks very much like a CSC one. The system is almost certainly custom made as that's what Powerflow specialise in.

It probably cost the previous owner £700+. As to BHP it's just about impossible to predict unless you have direct experience of before and after. About all that can be said is it should be better and it should deliver maximum benefits for any other mods you do.

Just as an example on this aftermarket manifolds for Peugeot 205/309 GTis have been shown to offer no benefit at all on an otherwise standard car. Some other cars (Fiesta / Puma) can give 8-10bhp more with a decent tubular manifold.

[rossocorsa]

It should make a nice difference to how the engine runs but I don't imagine big power gains maybe 5 to 10 bhp maximum exhaust claims always seem to be overrated and the VX engine is a bit strangled by the standard induction sytem. Interesting layout will be useful to know how it sounds and works in use as I will need a sytem for mine if it ever gets finished (I'm going slow due to lack of funds at the moment) I think GC recommends a 4 into 1 on forced induction rather than a 4-2-1 but it will still be better than standard and I will be fitting an old ansa 4-2-1 to mine as I can't afford a new one. What is the ID on the main run down the car?

[WestonE]

I can confirm this is a CSC front 4 into 2 into 1. For the VX larger primariy and secondary pipes are recommended in the now GC proven exhaust sizing data. The VX engines HATE exhaust back pressure so if your silencers are all straight through without reduced section sizes inside as the originals had you are doing well. It is a better exhaust design for a Beta 2000 on twin 45 Webers but still much better than standard where the manifold and first silencer box are seriously restrictive.

To get more performance you need good integration of induction improvements: Cold air in, DCNF or single DCOE plus cylinder head prep with porting and 3 angle valve seat cuts, plus uprated inlet cam typically Beta 2000 or 130TC inlet and of course a free flowing exhaust.

This sort of setup should see 160 -190BHP with far better throttle response compared to standard provided there is good compression and no fuel system or ignition faults. You risk the engine breaking at the higher end of this through the age of the pistons and rods and the lack of baffling in the sump. Guy Croft's book will give you a lot of this.

Eric
Building Beta Volumetrico Fuel Injection Beta Spyder and Montecarlo VX Fuel Injection.

     

[rossocorsa]

re the main bore size I checked my spare exhausts and they look like 44mm id but it's not too easy to measure??? I seem to recall that something larger than 48mm was recommended in tuned set ups.  Eric where is the specific info on VX exhausts in the GC book? I know I should know but I couldn't seem to find it on a quick glance, or maybe I need to pop in for a cup of tea and ask him (I don't like to say to much tbh as my attempts at engine renovation are very substandard and I'm wary to divulge my incompetence to him!!). Another question anyone know what OE VX exhaust ID was as I think most cars have IE exhausts on them now and the originals were different but never seemingly available in the after market? 

[VXdeMayo]

Dear Eric,
Thanks for that useful info. I would be interested in improving the induction side of things as the air flow into the supercharger looks very torturous! I would like to find a single DCOE or DCNF with approriate cams etc.
Assuming I go the way you suggest, what sort of MPG will I still be able to achieve with all that liberated power?
Best,
Chas,
(VXdeMAYO).

[andybeta]

VXdM,

That's a nice looking exhaust system. The manifold looks a lot like a copy of a CSC manifold which tried to copy the period ANSA extractor exhaust manifolds.

What sort of budget have you got? These sorts of mods are not cheap neither is GCs tuning work. It all adds up. Think of a budget and double, no triple it. Plus there is all the time involved unless you buy a car which already has all the mods done.

If you are thinking MPG now then perhaps these mods are not for you.

If you want consistent economy from your engine, as good as it gets with the Beta engine, I would suggest go the FI route as Eric has done as a carb is old technology and is never going to be as efficient as FI or give an engine that delivers power consistently across the rev range.

The max exhaust pipe diameter you can practically use on the Beta is 2.5 inches as any larger and you won't be able to get the pipes up and over through the space above the rear cross member and beneath the boot floor. Preferred extractor manifold configuration for the supercharged engine is 4-1 with approx 32 inch primaries. 4-2-1 can be used, some say it gives more torque, but still use long primaries around 30 inches with 12 inches for the secondaries. Fit a flexi section and boss for a lamba sensor as well. Go for just one rear box as long as possible as the standard rear tail box is quite short and there is plenty of additional space to make a longer box under the HPE boot floor.

Not sure if this type of exhaust gives massive increases in power but what it will do is reduce back pressure so the engine will rev so much more freely and to a much higher rev limit.

I think Don Pembleton of Huthwaite was making the exhausts for Powerflow at one point. He made the stainless 2.5 inch straight through exhaust system for my HPE VX. Very nice it is too.