Mods for 90's Citroen Break (STW for folks in US))

[jtbo]

Originally Posted by Piwoslaw

Oh, how nice it would be to lower the roof. If the car is a goner anyway, then why not have some fun?

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As for the Megane Coupe, I checked that is has Cd=0.33 and frontal area only 1.9m2 (as opposed to my 307sw's 2.55m2). Iirc the ZX's FA is closer to mine and has Cd=0.36, so getting the Coupe would score you a lot, especially if you don't need a big car. You could also look for the convertible version and make a custom aero hardtop, as proposed here.


Much more than we would like, but that's the price we pay for being better than the rest

I try to make some mods, but have to keep car legal and usable, also I'm mostly using scraps for parts, so that even there would not be much gain from mod, it will not cause more load to world, even I'm not really eco person, I try to do things reasonable way and there is no point of buying much new stuff for vehicle that is going to be replace by christmas if all goes according to my plans.

That of course limits a bit what I can do, so far only paint, tape and some rivets have been bought for mods, rest are odds and bits left out from other projects that have had no other possible usage, new tool I needed anyway and fiberglass I needed anyway to repair bumper.

Latest improvement was to add side supports for that last 50% of kammback, this time I had no more plywood available so found scrap pieces of thin metal, it was bit too little really, but I made supports from that anyway.

After driving some 30km on gravel road I did notice that it is not very good, supports are getting dusty from outside facing surfaces, so they are too much inward.

Other thing I did notice is that now dust swirls, there are two swirls at sides, like in aeroplane when landing and at middle there is tiny gap where dust is not rising so high.

Swirls rotate inwards, also rear window is still gettin bit dusty, not so much as before. Hard to really tell much of difference as there was not enough dusty roads to see full effect, only small areas of dusty roads. Rain would be rather good test.

I must still add 3rd brake light to lower part of window, so that it is seen by other drivers, I think that I have one unused one that I got free years ago as it was going to dumpster, yeah, I'm a hamster

ABS got broken again, just few weeks ago was fixed, did cost 180 euros, one of the gremlins in this car.

I was wondering if that cd value in database is for break or normal ZX? If it is for that hatchback then break would be bit more 0.02-0.04 is perhaps typically added for break/stw compared to hatchback, sedan being somewhere in the middle.

Megane and ZX are same size cars, imo, only that I now have break, but I really don't need one as I do have a trailer, aerohead would probably get excited about that one and if I would need to pull it more than once in two years then I might do full mods to it for sure

[jtbo]

Okay, I don't know if I did anything right, but I added now few things, to front I made small lip, barely visible in a photo, then I added wheel well covers, rears need still bit of work, some support so it does not look like curtain, but I'm yet to come by appropriate scrap metal.

You can see in photo that my kammback attempt, I checked that car's sideline is straight in gimp and measure bit under 11 degrees for first section and around 13 degrees for latter section (that has red metal supports). I think that those red parts could of been larger, but metal piece was so small that I got barely those two out from it.



Added new 3rd brake light too:


Yes, car is covered in clay, mud and who knows what, it is this time of year and these roads, no point washing car until about month or so.

I did some Flow Illustrator testing, but I don't think that it really tells much, front lip could be lower, but it is already around 60-70mm from ground and is touching ground on bad roads, good thing it is still flexible, might need some supports to that one too.

Black material is vinyl carpet, used in house floors, this one had lot of mould and it was rather small piece, just enough for car.

Rear belly pan and sideskirts are perhaps next that I will do when I will have time again. Underside is horrible, rear bumper is like U-shaped air brake, there is spare wheel too, I'm thinking of leaving spare wheel out and getting one of those bottles that promise to fix tyre, then I could put cover to that area so it would be smooth, probably largest effect.

I also did the ultimate mod:

[cleanspeed1]

Got to get the engine to run hotter. Evans Coolant ( biodegradeable, 375 F boiling point ) and raising the operating temp will help you gain mpg. Turn the engine fuel delivery down with smaller injectors ( I saw the hitch in the back, do you tow with it? ).
Heat the fuel up so that it reacts better inside the engine ( diesel needs all the help it can get to go from ambient to auto ignition point ), add propane or cng assist as a range extender. If you are feeling real frisky, get a cam ground or find a factory camshaft that brings the torque peak in at 1600 or lower rpm, and modify the fuel delivery so that the powercurve peaks quickly and falls off ( like a semi truck engine, car diesels keep the powerband flat and long so that it accelerates well ); see if your engine is used in commercial apps that require that type of powercurve and use it.

[jtbo]

Originally Posted by cleanspeed1

Got to get the engine to run hotter. Evans Coolant ( biodegradeable, 375 F boiling point ) and raising the operating temp will help you gain mpg. Turn the engine fuel delivery down with smaller injectors ( I saw the hitch in the back, do you tow with it? ).
Heat the fuel up so that it reacts better inside the engine ( diesel needs all the help it can get to go from ambient to auto ignition point ), add propane or cng assist as a range extender. If you are feeling real frisky, get a cam ground or find a factory camshaft that brings the torque peak in at 1600 or lower rpm, and modify the fuel delivery so that the powercurve peaks quickly and falls off ( like a semi truck engine, car diesels keep the powerband flat and long so that it accelerates well ); see if your engine is used in commercial apps that require that type of powercurve and use it.

Fuel is heated to coolant temp before injecting into motor, filter is in same housing as thermostat is, so when cylinder head warms, also fuel warms, it is great in our winters, where temperature can drom to -40C.

To heat air, that is easy as it requires only limiting air flow to intercooler, however it is very easy to to loose power and get excessive diesel consumption with that.

I don't tow too much, once in two years, but most of time I have 200-300kg of load in trunk, so I'm pretty much always driving near gross weight limit, this means that climbing those long hills means lot of load to engine and this means again lot of heat. Current grille block is about maximum I can have and still be able to climb hills without crawling, but when coasting temps tennd to get bit lower, that engine is producing quite a bit of heat for a diesel, also headgasket is common failing point so I'm bit afraid to get too much of heat there.

There was one valve for turbo cars, which lets pressure to wastegate actuator only after set pressure is reached, this causes turbo to spool up earlier as wastegate is not open at all until pressure is reached and such would bring more torque to lower rpm if I'm not horrible mistaken.

I'm running at 1850rpm @50mph which is what I can drive with that car, maximum torque comes at 2250rpm from my memory, however at least before mods putting bigger tires under the car caused rpm to be too low for car to run well, diesel consumption did increase dramatically, even with hypermiling I had hard time to meet rated consumption levels, surely car did have power in reserve, but I had to push pedal down more so that turbo came into play, but if turbo would come in with less throttle, then I think that I could save a bit with bigger tyres.

[cleanspeed1]

What kind of injection pump do you have?

[jtbo]

Originally Posted by cleanspeed1

What kind of injection pump do you have?

Mechanical Lucas, Bosch would be better, but of course car had not that one. Lucas is PITA to tune as screws are hidden under blind plugs and so that one can't see there without tiny mirror.

There is not much electronics in a car, old fashion engine with old fashion mechanical management, that I kind of like, less to worry.

edit: I don't know if I did this horribly wrong, but I got these:


Perhaps not so good improvement in reality, but at least there is some change.

[Piwoslaw]

The mods look quite good on your pics

It appears that the sides of the red Kamm extension are drooping inward. My guess is that they shouldn't be - the airflow will detach too early and they won't help any. But the top looks OK, as do the skirts.

And I love the sponge under the gas pedal: It lets you now when to stop pressing, but still allows max acceleration when needed.

The yellow circle with the '80' is to let other drivers know that you don't expect to go faster than 80 km/h, correct? Does that really help reduce the number of tailgaters?

[cleanspeed1]

Originally Posted by jtbo

Mechanical Lucas, Bosch would be better, but of course car had not that one. Lucas is PITA to tune as screws are hidden under blind plugs and so that one can't see there without tiny mirror.

There is not much electronics in a car, old fashion engine with old fashion mechanical management, that I kind of like, less to worry.

edit: I don't know if I did this horribly wrong, but I got these:


Perhaps not so good improvement in reality, but at least there is some change.

Ok, so it's a Lucas CAV ( rotary ) pump, similiar to the one used on the early Cummins 5.9. It may be a pain in the butt to get to the screws, but there is gold in changing the settings. Add more timing but cut the fuel back. If you are not comfortable doing it, you are in the best place to do diesel tuning. Between the Germans and the Finnish, there has to be someone that can optimize the torque curve for lower rpm operation.

[jtbo]

Originally Posted by Piwoslaw

The mods look quite good on your pics

It appears that the sides of the red Kamm extension are drooping inward. My guess is that they shouldn't be - the airflow will detach too early and they won't help any. But the top looks OK, as do the skirts.

And I love the sponge under the gas pedal: It lets you now when to stop pressing, but still allows max acceleration when needed.

The yellow circle with the '80' is to let other drivers know that you don't expect to go faster than 80 km/h, correct? Does that really help reduce the number of tailgaters?

Yes, just a tiny bit inwards, they are almost straight, but last piece of black top side was bit narrower than first part, of course this is the idea of kammback to narrow towards rear, but it would require rotating sides and that I did not manage to do properly, so there is tiny bit of curve on support, mostly on other side, while other side is pretty much straight, I have only thumbs on my hands, someone forgot to install other fingers at factory

Anyway dust seem to settle to red support pieces of Kamm so that means they are too much inwards, I could try to bend them more outwards when time permits, it is quite thin metal so easy to work with bare hands.

Sponge is very old trick, they used that already in 60's in here, probably the most effective mod, when tuned properly, it should not be too restrictive but not too easily compressing either, should be set so that when foot is resting on pedal relaxed, then you are travelling normal speed on level road, so it is bit like drive by load cruise

80 sticker on back is required here if car is converted to van class, cheaper tax and insurance, but not allowed to drive faster than 80km/h, I have not really converted mine, but as I don't see anymore point trying to drive 100km/h because there is very short pieces of such speed on our roads and even on those sections there are always many drivers driving slower, so I drive only 80km/h.
It helps on faster roads and there is not much tailgaiters anymore as I put that sticker on, they are now kamikazes that overtake at insane places, but I often show when it is ok to pass and usually slow down or go side of road just to make road bit safer, when others seem to be uncapable of doing even small amount of reasonable thinking.

It seems to be rather difficult to cut that last 0.3l/100km, but maybe with mods it will be possible.

[jtbo]

Originally Posted by cleanspeed1

Ok, so it's a Lucas CAV ( rotary ) pump, similiar to the one used on the early Cummins 5.9. It may be a pain in the butt to get to the screws, but there is gold in changing the settings. Add more timing but cut the fuel back. If you are not comfortable doing it, you are in the best place to do diesel tuning. Between the Germans and the Finnish, there has to be someone that can optimize the torque curve for lower rpm operation.

I might ask some quotes next week, don't like to mess pump by myself as my job requires to have a car and I need to travel really a lot with it, again tomorrow I need to fill the tank, will be really poor MPG as I have been driving on very soft roads and one night had to forget hypermiling and drive rather quickly, so I would not be surprised to see lowest MPG, but car has surprised me before and now I have mods on, so let's see how it goes.