Bongo Fury

Ok - I believe I am ploughing my own furrow here (but I am used to that!!) so a bit of an update but first a re-cap.....


Having bought a 4wd diesel Bongo the engine gave up the ghost and it wasn't the head gasket!!!!

Some Japanese bodger had bodged the engine back together after the tip of a glow-plug had dropped into the engine. Cutting a story short, bottom-end was shot but kept running for a couple thousand miles perfectly OK then no go. Head was OK apart from a little bit of shrapnel and a glow-plug shaped dent!

As the head wasn't immaculate (and whilst my new bottom-end turns up hopefully being fitted as we speak) I decided to clean-up and rebuild the head as it was full of oily sludge in the inlet ports and manifold. Whilst cleaning the head up I noticed that the ports are quite constrictive due to poor casting/machining and design with the pre-combustion chamber bulging into the inlet ports but they at a nice semi-down draught angle. The main problem area is where the valve seat inserts sit into the ports (valve throat area) and also where the pre-combustion chamber bulge encroaches onto the valve throat area.

With my trusty dremel and other tools I blended the valve throat area to encourage good gas-flow and smoothed out various, numerous lumps and bumps in the head and inlet manifold including the valve guide boss area. I also polished the backs of the valves as they were covered in crud and had a nasty ridge around the valve head. I lapped the valves in, one of the exhaust valves was peppered with glow-plug fragments stopping it sealing so I repaired that and also fitted new valve-stem seals. .

At this point those of you who haven't already given up reading this are probably thinking why do such work on a slow revving diesel van and not a race car? Well..... my thoughts are that the standard bongo head constricts the flow of air into the cylinder head even at low revs. Improved cylinder at lower revs filling will mean better power at lower revs leading to better efficiency/MPG.

The turbo itself didn't escape unscathed. The mouth (inlet) of the turbo had a step in it so I removed the step and tapered the mouth outwards as where the turbo meets the pipe from the air filter there is quite a step/change in size.

I picked-up an early Celica charge-cooler cheap off ebay (it was listed as an intercooler) for those not in the know a charge cooler is basically an inter-cooler immersed in a water jacket as water is much better at heat transfer and also the chargecooler can be placed anywhere such as closer to the engine shortening the length of pipework from the turbo to the cooler to the inlet manifold (there is a few metres of it on a diesel bongo!) This would mean that the shorter length would mean the turbo wouldn't have to pump the air over such a distance and would build up pressure quicker due to a much smaller volume of air in the pipework therefore less lag. Also the chargecooler cooling air more efficiently would mean cooler denser air (cooler air is better for combustion, the denser the air the more oxygen by volume it contains).

I have still to experiment with the chargecooler to see if it will work vertically instead of horizontally as it is the only way it fits between the block and the fan but the inlet and outlet holes line up perfectly. The chargecooler will have it's own coolant set-up with an electric pump (another well-used ebay cheapy) lengths of hose and a motorcycle radiator (yet to purchase) at the front. I can't decide whether to put the chargecooler radiator where the standard intercooler goes or right in front behind the grill. Any thoughts?

I have removed the EGR and will be blanking them off for obvious reasons. I am also considering removing the crankcase breather from the inlet pipework and simply running a hose to the back of the van and venting it there as having hot spent gases in the inlet pipework does nothing for combustion.

I'm sure I have missed things out but as you can see I am quite ambitious and possibly mad! Hopefully though this will lead to a more efficient Bongo engine. Either way it will have cost me mostly time, only a little bit of money and a lot of brain-ache! If people are interested I will take a few pictures and if there is real interest I will remove the cam and a few valves to show people the ports.

Any constructive ideas or thoughts?

Not got my Bongo yet - just ordered one.

Only idea I can give you off the top of my head is : Does the Bongo traditionally suffer rust in any one area underneath? Particularly notorious box section somewhere etc? If so, then that's where I'd be plumbing the re-routed breather to.

I did this on a 2CV based kitcar many years ago. 1974 chassis, built into a kit car in 1984. Still going strong now with the engine breather plumbed into the main chassis box-section. No signs of rust. Got the idea when restoring 2CVs - they always rust in the chassis / floors, but never up near the engine due to the 'protective' oil leaks. Can't be many cars still driving around after 35 years made of French steel.

Commendable mods you're planning to the Bongo though. I'll be reading with interest.....

Interesting stuff that... good for you!

Top end work is certainly something I have wanted to do to mine, especially when there is so much room for improvment on the production standard. If my head ever comes off, I will be doing the same. I will be interested in seeing the effect of the chargecooler.

Has anyone ever tried winding up the boost on the turbo? If so, how far did you go before it went bang?

I agree, fascinating thread, keep us posted.

Thanks guys.

What kind of kit-car was/is it? One of those 3-wheel Morgan style ones? They look like fun! I read about a stream-lined 2cv based 3-wheeler mostly made of wood in Practical Performance Car with 5 gears and incredible mpg and good performance to boot!

As per routing the breather in the chassis, the fumes from breather can be quite noxious and as much as I would like to stop it rusting if the fumes get inside then it isn't good. The breather pipe if I did it would exit right by the rear bumper.

One trick racers (and boy racers) often do is feed the breather into the exhaust via a little pipe protruding into the exhaust stream with a slash-cut facing down stream. This creates a vacuum helping draw out the crankcase fumes. It also makes the emissions read higher from the exhaust at MOT time!

Space is tight for the cooler and I have to jiggle the fan over a bit and make some brackets and test to see whether the ropey electric water-pump works with the chargecooler the wrong way round!!!

It was inspired by a Lomax (They do 3 wheeler/Morgan style and a 4-wheeler version) - but TBH they aren't too pretty, so we borrowed the lomax chassis mods to lower and level the 2CV chassis, and made a one-off body. Steel frame with aluminium skin, and a couple of 2CV panels grafted in for good measure.

http://www.facebook.com/album.php?aid=2 ... 1463373183 <- the image thing didn't work!

I like it! Looks like the bastard child of a proper Lotus 7 and a 2CV! is the engine standard? They sound quite mean uncorked! My understanding is that the Citroen GSA 4 cylinder air-cooled lump could be slotted in, also the Citroen Visa barrels and heads were used to upgrade the 2cv to a whopping 650cc!

My dad used to have a 2cv, great fun on Cornish lanes, he used to drive it flat-out at any corner and bounce around! less weight and lower c of g will equal even more fun!

Sounds like a great bit of work you've done - I'll be really interested to read how the motor runs when it is fired up. Fingers crossed 4u

Your description is pretty much spot on. The engine started life as a standard 2cv lump (602 cc, 29bhp). When I sold it the engine had been bored to 650, visa pistons, gas flowed heads and a 'knotted stick' camshaft - one of a short run of cams made by a 2cv racer in Glasgow. (Have you seen 2cv racing?). Also had a revised gearbox using some Dyane ratios and a higher final drive. It went really well like that - could easily run out of numbers on the speedo in top. (Only went up to 110KPH, I could get the needle round to 0 on the wrong side of the endstop, about 100mph). Handling was fantastic. Sounded like a very angry wasp driven hard. The next owner ended up replacing the engine and box for standard ones - never did find out why. Still tops 80 like that though.

I looked at the lomax 424, which has the GSA engine but the extra weight spoils the handling and the extra lump makes it difficult to get the bodywork pretty. I did have a 1300 4-pot 2CV for a while (rebodied Ami Super). It went like a rocket, rolled more than a standard 2CV, doors started to open at the top above 100mph. All in all a truly terrifying machine. Gave it away.

My dad still has the Mk2 version of my car, which he built a few years later. 650cc, twin bike carbs, slightly different bodywork. Goes very well.

Aye, we're slightly mad!