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Superspec Turbo Diesel


Guest samss

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Guest samss

After owning the superspec for 12years but having been off the road for most of that, I decided it was time to get her back on the road!

 

I've had a long term desire for a fast diesel, and after falling in love with the "superturbodiesel" scene a few years ago, I'd slowly been collecting parts to make my vito van into a 500bhp monster. This project hadnt been progressing, and the van was slowly falling to pieces. The mrs rightly said "keep one, kitcar or van". So the decision was made!

 

So far the spec of the 'spec is as follows:

 

- 3litre straight six OM606 turbodiesel engine as found in the 1996-1999 era merc e-classes. Theyre 176bhp as standard i believe and are fuelled by an electronically controlled fuel rack yet mechanical injection pump. This means they have an ECU which can only control boost and the fuel rack position.

 

- Holset HX40 from some large truck, this is capable of 500bhp worth of boost, although it may be oversized for the hood, and be laggy and lack low end boost, as I have it I will try it!

 

- Mercedes 722.6 Electronically controlled 5 speed automatic gearbox. It's from a larger power engine so has a higher torque ability before slipping than the standard e-class one, although its essentially the same gearbox. This will be controlled by a stand alone ECU which will support a sequential gearstick (had paddles on a smart car, not sure i like that)

 

- large Air to water chargecooler allowing remote mounting of the cooler radiator.

 

To accomodate all of this the engine radiator will be rear mounted, ducting air from underneath through vertical mounted radiator and out large louvres and the apare wheel will be incorporated as a vent.

 

- the differential will be the mercedes eclass one as they are proven to take obscene amounts of torque, whereas sierra ones seem limited, although i'm not sure how much torque it will see before spinning the wheels up! By chance the lobros are same size as sierra cosworth ones and shaft length will be same as the diff flanges are same distance apart.

 

The usual method of producing serious power with a om606 engine is to swap the injection pump for a modified larger element rebuilt manual pump. However I'm opting for a standalone ECU and uprated electronic pump. This will communicate over CAN with the gearbox ECU allowing the possibility of cruise control, torque limiting on gear changes to protect gearbox, and all sensors to be shared. It will also allow me to run smoke-free by means of altering the map, allegedly!

 

So far I have got the engine and gearbox into position, this required only the front rover engine mount crosstube to be removed and some footwell mods. I will replace this tube slightly further forward. The passenger footwell requires narrowing 15mm to allow movement of the gear selector cable mechanism. The tunnel requires slight modification to allow the thicker propshaft clearance.

 

Amazingly the length of the engine doesnt really pose a problem. It is tight, but not too tight. The gearbox back end just clears the chassis tubes, there might be 5mm in it! The clutch pedal area of the drivers footwell has been modified and will make use of a "footrest" to hide the modificaion to make room for the gearbox cooler pipe banjo. The height means the bonnet will need a bulge, however I have decided to lift the scuttle and bonnet and nosecone to avpid this as i am yet to see a bulge that i like. It would need 50mm to clear and allow movement on mounts, however having driven a lowered beetle round and realising the state of the roads has declined somewhat I realised I should make the sump as high as possible so have made the bonnet clearance 100mm taller. I have some 100x50 stainless box to do this with. It may look odd being taller, but then it is an odd project!

 

The engine mounts on most rwd mercedes are two giant bobbins that bolt vertically through engine mount arms and into the subframe. I was concerned about strength of the chassis in this area as its in the middle of the run between front suspension and where the tubes are tied together around the steering column area (where original superspec mounts were). I decided a simple box section subframe was the best solution that could span under the engine (no lower than sump) this would tie the side rails together side to side and the 3x members vertically. It should be very strong. Yes it will be heavy, but The superspec is no racing car, it always was a larger cruiser!

 

Updates to follow!

Sam

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Guest samss

The mostly complete cradle frame. Just needs sleeved holes, and the ends capping off.

 

post-14091-0-69042400-1500247726_thumb.jpg

 

 

 

Having a practice go at some TIG welding some stainless brackets onto the stainless chassis. The finished brackets on the chassis didn't turn out anything like as neat as this! But.... aslong as it's strong, I'm not too bothered, as it won't really be seen. Turns out welding in situ is alot harder with TIG than it is on the bench. Mig is so much more "point and shoot".

 

post-14091-0-62321900-1500247727_thumb.jpg

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Thats an interesting plan.

Proves my theory that all Hoodies have inbuilt "tinkeritis".

Best of luck with it....it should be fun.

Ive had a chipped 2.2 Citroen C5 and a chipped 320D. They were both

great fun, 175 bhp & 198 respectively but loads of lazy torque too.

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