Brazilian Kombi - Exhaust Options

Another issue! More new parts required.

OK driving home from work this evening I heard a scraping sound every wheel turn coming from the rear off-side (drivers side)

Just about to join a major roundabout the noise worsens. Oh great, my initial thoughts turned to the major works I did a few months ago (see earlier posts) so I had a mental image of a CV joint and drive shaft dragging on the road.

So went round the roundabout and back to a small side road. Pulled into a space and decided to reserve into a better space to inspect, fearing the worst.

When reversing there was a allmighty noise and loud bang.

So got out and found the exhaust final box sitting on the tarmac.

Oh.... at least its not the gearbox......

Put the rear box in the sliding door and got out the inspection lamp to inspect for any damage. NONE! Clean break at pipe. No damage.

Ohh... off I went.... sounding like a monster truck / tractor or boy racer.... took it slow on way home but made the 16 miles avoiding police cars and cruising mainly in 4th gear to keep the noise down....

So NEW Exhaust required - Been putting this off for a while (Exhaust filler and jubilee clips to hold the boxes together)

Right onto the main reason for this post - WHICH EXHAUST should I buy?

Here are the options:

Brazilian Bay

Stock System:

Stock Costings:

VW Heritage:

Stock Steel.

Silencer, Left, T2 EFI VW Brazil Aircooled 1600
Left hand side exhaust silencer for Air-cooled Brazil Kombi
Part ID 040253609
£131.95

Silencer, Right, T2 EFI VW Brazil Aircooled 1600
Right hand side exhaust silencer for Air-cooled Brazil Kombi
Part ID 040253610
£116.95

Gasket, 3rd joint, VWB Kombi

3 hole exhaust gasket joins left and right hand sides towards front of engine.

Part ID 040251509

£4.01

Total = £131.95 + 116.95 + (4.01*3) = £260.93

Cool Air:

Stock Steel.

Exhaust Silencer - Aircooled Brazilian Bay - Left, EFI

Brazilian Bay Danbury fuel injection exhaust for all Aircooled Brazilian Bay Buses.Left Hand Side.

Part ID 040253609

Price: £129.50

Exhaust Silencer - Aircooled Brazilian Bay - Right, EFI

Brazilian Bay Danbury fuel injection exhaust for all Aircooled Brazilian Bay Buses.Right Hand Side.

Part ID:040253610

Price: £114.50

3 Hole Exhaust Gasket - Brazilian Bay

Replacement 3 hole exhaust gasket which joints the left and right hand side 3rd joint of the exhaust on all aircooled and watercooled Brazilian Bay Buses.

Part ID: 040251509

Price: £3.50

Total = £129.50 +114.50 + (3.50*3) = £254.50

Longlife.

Brazilian Bay special price from Longlife Exhausts (Swansea)

Left & Right boxes + Pipes Stainless Steel

£359 Delivered.

Early system

This early system was fitted to Brazilian Kombis in the 1990s. Neat simple BUT impossible to buy in the UK and very hard to find even in Brazil! Hens teeth!

Custom Options

CSP make classic bay parts. Could use the muffler but on further investigation the flange is the wrong size and the tail pipe exits on the wrong side so the tail pipe will face upwards and clash with the valence. There are CSP parts so they could be bought in parts and a system "could be made to fit" High risk and expensive.

CSP Universal Parts:

Universal high quality CSP Python exhaust performance muffler 2,5"

Vintage Speed:

This is the heater version

This is the merged version with no heaters and also equal pipe lengths from both sides.

The vintage speed has been fitted on one other Brazilian Kombi owner and is said to pass an MOT even without the stock CAT fitted. It has the Lambda port (right hand side) so ECU and injection system will be happy.

Short and compact and trusted on many a classic bay.

Only risk is it fails the emissions test as there is NO Stock CAT.

Vintage speed prices:

Box £380-410

J Tubes £80

Options Table:

Name	Description	Price
Stock Steel	Steel 2 Boxes, rusts, stock emissions	£260
Stock Longlife	Stainless Steel 2 Boxes stock emissions	£359
Stock Header+J	Stock Header system - Steel Only available	£300
Stock Early	Single Box - Not available	N/A
Custom	Kit form s/s expensive parts, assembly costs No CAT	£300+
Vintage Speed	Simple s/s, Lambda port. No CAT, emissions unknown	£460

After considering the table my main options are Longlife (Using my older header and CAT) OR Vintage speed

Which one? I will sleep on it...............

Running Rich - Exhaust Investigation

As part of the investigation into the apparent running rich mixture and higher fuel consumption I have started working on looking at the last piece of the "jigsaw" The exhaust.

I have been thinking that the exhaust system could be partially blocked or  restricted either by the CAT or the two exhaust boxes.

This would lead to back pressure where CO etc in the exhaust was coming back towards the lambda sensor causing the typical 0.8 to 0.9 readings. Also this would also cause the exhaust analyser to try to suck air during the MOT sampling causing the over Lambda (o2) reading

So I managed to find a second hand CAT from e-bay and some new gaskets. Plan was to remove CAT inspect and run diagnostics to see what Lambda sensor reads without CAT or any exhaust restriction. Then try "new" CAT to see if anything changes.


1. Removal of the CAT involved soaking the bolts in penetrating fluid over night.
2. Bolts where not that bad to remove. CAT came out - noticed that a gasket was missing from the CAT out side.

3. Inspected both ends - Both looked like running a rich mixture. Lots of black soot on both ends.

4. There is no sign of blockage of any of the honeycomb inside the CAT. Seems not to be blocked but unsure of any catalyst material or function. 

5. Ran the engine without CAT It was very very noisy sounded great but I am not sure the neighbours where too impressed!

Captured a diagnostic log of the usual functions (rpm, coolant, injector, engine load).

   
From the graph you can see that sensor warms up quickly dropping down to a lean level of 0.1 / 0.2 engine does richer upon acceleration. I would expect the engine to run lean as the lambda sensor is fitted just before the CAT so would be quite lean exposed so close to air.

If I compare this to a typical run with full exhaust fitted it normally goes straight to rich 0.8 / 0.9. Did not dare take it for a drive but would have been interested in knowing if any changes to injector timings would happen.

Removing CAT and having an unrestricted exhaust does improve mixture (all be it a little too lean)

6. While I was under the van working on the exhaust I thought I would treat my van to some new exhaust hangers.

7. Carried on not sure if to put on new CAT but decided if I did not change anything then I would just get the same result again. New CAT was similar but looks like to be a different shape. Maybe a replacement from the original Brazilian one.

8. Once new CAT was fitted took the van for a drive along my "typical" A6 drive which gives two dual carriageway constant speed sections.

Logged the data as before.

Did not manage to capture the initial warm up but still the two humps at the start are the same sections as other logs.

As before there seems to be running yet again as constantly rich (0.8/0.9)

Changing the CAT has seemed to have no effect on Lambda levels. So I suspect its running the same as before

so what I have learnt? I think the following:

1. CAT does not look restricted but running rich for so long will reduce effectiveness.
2. Running free non restricted exhaust does not show a rich mixture.
3. If exhaust is restricted then it must be CAT or two boxes further.
4. To confirm I will remove the CAT to BOX 1 connection and re-test and remove connection from BOX 1 to BOX 2 and re-test.
5. Try the back pressure measurement. No idea of how much back pressure is acceptable.

I think there is a possibility of a restricted exhaust. so will need a new exhaust but the choices are:

1. Stock steel - VW heritage sell Box 1 / Box 2 for approx £250
2. Longlife Stainless - £359 for stock but stainless.
3. Remove all including the CAT and opt for a S/S vintage with Lambda port £410

I am tempted by the vintage speed BUT concerned without a CAT it could fail. I think Stainless Steel Longlife is good BUT expensive £££ but at least will last and an investment.


UPDATE - Did the back pressure measurement - Connecting into Lambda port.

NO BACK PRESSURE AT ALL - ZERO PSI at idle and only 1-2 PSI on acceleration etc. SO no back pressure.