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Brummie

Brummie's G50-into-an-SC transplant

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Very Interesting and well written. Look forward to following the progress through to completion. :)

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Finally finished off the underside ....... the new rear bulkhead now fitted along with the plated in center tunnel and rear seating area. Parts of the center tunnel are now double skinned for added strength.

Refurbed the flapper boxes as I plan on hooking them up to the 993 heat exchangers and working them via some sort of cable in a similar way as original.

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Blanked off some of the original holes in the rear baulkhead which will not be used. I decided to use fibre glass here as I may at some point want to use them and removing fiber glass will be a lot easier than if they're welded. Made up some new copper brake lines and fitted along with new tube nuts and union.

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Fitted the rear suspension and torsion bars with the oil tank, all very tight but it is still possible to remove the oil tank without dissmantling the suspension..... ask me how I know.

Ended up having to use an allen bolt in the top fixing for the spring plate as it was just impractical to get a hex head in.

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Fabricated a front gearbox mounting bracket, this fits to the front of the gearbox and original cross member. Needed to fit some slightly longer M8 studs to the gearbox to allow bolting up to this bracket. I'm also utalizing the M12 fixing which the 993 uses to bolt a torque bar to, this now bolts through the cross member and into the gearbox case for added support. A small spacer is needed here to fit between the two faces to prevent distortion. Finally new mounting bushes and washers hold it all into the chassis, I'm using standard mounts for now but may have to change these later.

 

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Next up was the starter motor, I decided to go for a standard 993 starter then make a 19mm packer to space it correctly to engage with the starter ring. A bush then had to be made to support the front end of the starter as the original support ended up being machined away when the gearbox was initially shortened. A standard 993 phospher bronze liner should make for easy replacement as it wears.

 

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I wanted to keep the standard 993 heater blower and air cleaner, in order to do so the engine lid hinges needed to be modified. Firstly spaced out the hinge pivot points by 30mm on the bodywork and added a support plate, next weld on a small plate to the top face the 993 hinges to line back up with the engine lid. This now fits great and clears everything

 

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Next stage engine in and wire up......

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Great work Brummie, it's all looking so good.

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Love it, but that thermostat looks low, will it need a guard or something?

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Excellent stuff.

 

How are you going to make the speedo work?

 

Need to know as I now have 993 box in stock ;)

 

I think I am going to go for the pick up ring on the diff like a G50 Carrera.

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Love it, but that thermostat looks low, will it need a guard or something?

 

It is lower than I'd have liked Nige but its just not possible to raise any further....... I don't think it'll be a problem depends how low you like your ride.

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Excellent stuff.

 

How are you going to make the speedo work?

 

Need to know as I now have 993 box in stock ;)

 

I think I am going to go for the pick up ring on the diff like a G50 Carrera.

 

Not sure if its possible Mr Tea to fit the sensor ring on a 6 speed G50, Mike at MB Engineering's your man.

I was originally going to adapt an old 915 sensor ring but have now changed it for something a bit stronger. I've made a stainless steel disc which mounts to the CV joint, on it are 8 small threaded magnets which a sensor will pick up, its pretty popular with the mid engined Ultima boys.

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Update:

 

Engine and gearbox installed, throttle cable and gear lever connected, clutch cylinder bled, vacuum pipes and fuel pipes connected, drive shafts fitted. I was originally going to use the SC drive shafts and CV's but I've since been talked out of it, instead I'm now using the G50 type.

Time to sort out the electrics.... I'd been putting this off for a while after trying to make sense of the engine electrics and the 993 electrical drawings...... they're pretty confusing at best, it's certainly a test of patience. When I bought the 993 engine it also came with the Motronic ECU, the rear half of the cars wiring loom, the rear fuse box and the engine wiring harness. To help integrate this lot into the original cars wiring I bought a Patric Motorsport conversion kit which has a series of plug in connectors along with various wires connecting into the cars fuse box. The conversion kit has a fused live supply and an ignition live for its DME relay, there's a 12v supply coming from the DME to the old SC fuel pump relay, there's also a new cable from the ECU which will trigger the rev counter. The DME relay and ECU all sit on a chassis plate which mounts under the passenger seat, also mounted on it is an OBII socket for accessing the engine management and a decent earth cable which mounts to a good ground on the car. There's a number connections which are needed to be made from the motor to the original cars loom, I didn't really like the adapter harness that was supplied with the Patrick conversion kit so I decided to do away with that and adapt the harnesses together by soldering the necessary wires. This was all done in the engine compartment inside the fuse box, luckily it's a big enough box to accommodate the wiring connections but more importantly it has all the proper plugs and sockets for the engine loom to connect to. Quite a lot of the wiring colours have remained the same over the years between the two models but there’s still a fair number of new wires from the motor.

 

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Next the exhaust..... One of the reasons I had for relocating the oil tank was to be able to fit a decent balanced exhaust but the original 993 system is far too big, heavy and bulky. I also wanted to do away with the cat so I looked at a number of different bypass systems before finally settling on one from Supersprint. Supersprint were very helpful and gave me all the information I asked for so I could measure up for sizes and clearances. The other thing I liked was the Supersprint silencers, they are about two thirds the size of standard porsche units and unlike those these would fit in without too much modification. The whole system is beautifully made from stainless steel, it fitted perfectly with just a small cut out on either side of the inner bodywork to give clearance to the silencers. I've also wrapped the tubes in exhaust tape in an effort to contain some of the heat, not the prettiest solution but incredibly effective. A little local heat shielding will probably also need fitting but I'll wait and see how hot it all gets first. I've got a couple of fiberglass rear valances which I'll cut up and join to make one complete full length piece when I'm happy with everything....... I'm still messing around with tail pipes but it looks like some simple round tubes work best.

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With the exhaust fitted it was getting close to turning the key, before that though I wanted to try and get some oil pressure up and showing on the gauge. The book says it takes about 11 litres to fill an empty 993 system and that's pretty well what it took, it didn't take too many cranks of the starter for the green light to go out and the needle show signs of life by jumping up the gauge. Next I bled the fuel rails by wiring the fuel pump directly to the battery and pressurizing the system, there's a bleed point on the rails to do this and once all the air was out I reconnected the fuel pump and broke out the fire extinguisher ready to turn the key....... It’s been a long time coming and amazingly it started first turn.... a quick check on the vitals and then it just cut out, I tried it again and it did exactly the same thing. After checking it through I got it down to the fuel pump relay. Power was only being supplied to the relay while the starter motor was operating (position 3 on ignition switch) allowing the engine to start but once the key was released (position 2) power to the relay was lost hence the cut out. A little wiring mod sorted that out so re-tried it and this time it ran great, again a check of the vitals, all gauges reading correct, alternator ok, oil pressure good, no oil leaks so I let it warm up checking everything as it did so. It took a little while for the thermostat to open and electric fan to kick in but it all appears to work ok and keep the temperature stable...... It's a testament to Porsche engineering, this engine was taken from a car which was substantially written off, not run for a couple of years, have countless parts replaced or adapted and yet it just fired up without any complaint as if it had been used daily. I know not everyone on here has had it quite so easy and there's plenty that can still go wrong but when they're good they're bloody great....... can't beat old air cooled lumps.

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Good work Brummie, soon be on the road. :signs118:

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Nice one Brummie, looks really good - what a cracking project :ani_clapping:

 

The Patrick loom doesn't look any better or worse quality than the Timmins loom really, I thought people generally rated the Patrick one slightly higher.

 

That looks quite some exhaust set up that you've gone for. There are a lot of bends and a long way for the gas to travel before it escapes. How come you plumped for that rather than something like a happy crab or a single rear box?

 

Looking forward to hearing your thoughts about the first few drives :)

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Brummie's exhaust is top notch - and he can get away with it because his oil tank is now tucked away up behind the door latch panel. If you stick with the stock 3.2 oil tank you'd not have any room for an offside silencer in that location. This project really sets the bar for 3.6 conversions.

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I think I've already used up all my "top work", "looks great", "wow" comments in this thread - can you do some sh1t stuff now please to balance it up a bit!

 

Have you had a drive yet?

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Brummie's exhaust is top notch - and he can get away with it because his oil tank is now tucked away up behind the door latch panel. If you stick with the stock 3.2 oil tank you'd not have any room for an offside silencer in that location. This project really sets the bar for 3.6 conversions.

 

^^ what he said. This is one of the best conversions ever in so many respects. Exhaust looks great - should flow very well and has enough length and volume to actually quiet things down a bit.

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Impressive stuff as ever, makes me feel inadequete :lol:

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It's a testament to Porsche engineering, this engine was taken from a car which was substantially written off, not run for a couple of years, have countless parts replaced or adapted and yet it just fired up without any complaint as if it had been used daily.

I think you deserve some of the credit too, as it's clear this is an exceptionally well planned and executed conversion. I wish I had the skills.

Enjoy that first drive...!

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Fantastic Brummie :)

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Just a quick point on the fuel pump relay, you probably know this though, does it run when the engine isn't running now? It's like a two stage thing so the fuel pump is only pumping when it's needed, it's more of a fire safety issue if you have an accident and the engine stops but the ignition is on you don't want the fuel pump running, especially if the lines have become split.

 

I had a similar thing with my 912e when I converted to carbs, took me ages to figure what the problem was. When you turn the key the pump fires with the starter motor, once the engine is running the ECU recieves a signal to keep power to the pump. If it doesn't the pump stops. I wired it up directly on the ignition but later installed a fuel pump cutoff relay that senses if you taken a bump and cuts the fuel off. I think Ford fitted some over sensitive ones to Seirras a few years which would cut the fuel off if you hit a pot hole.

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Thanks for the comments everyone, certainly feels great to hear it running after all this time.... Not been able to take it out on its maiden run yet as it has no brakes. Got a nice set of 964 front and rear calipers I'm refurbing and mounting onto some turbo discs, they're well under way so not too long........ hopefully then I'll be able to catch up with some of you guys.

 

Alex, this type of system actually has less restriction.... effectivly each bank of cylinders has its own exhaust, by using standard manifolds and large bore pipes gas flow isn't restricted just muted a little..... I also plan on using the car regularly and didn't want it too loud, this should keep the noise level down a bit inside the car but it still sounds awesome. The functionality of the heating system was also up there on the list...... the little lady doesn't like getting her tootsies cold.

 

Yes you're right Nige..... On pre ECU cars the fuel pump relay actually works opposite to how you imagine, it's energised by the ignition when starting the car via one set of contacts in the relay feeding the pump then once the engine is running the relay switches off but there's a second set of contacts in the relay which are fed via an air flow sensor switch, this monitors the fact that the engine is running and allows the pump to continue working but if the engine stalls then the fuel pump cuts out as the air flow sensor sees that the engine has stopped. With the later cars like the 3.2 Carrera the ECU switches on a DME relay which in turn powers up the fuel pump, if the car stalls the ECU switches the DME off and cuts power to the pump..... both ways are fail safe for safety reasons.

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Cheers Brummie, I don't really understand the principle behind exhausts - The aim is for a free flowing exhaust but still retain X amount of back pressure so presumably it comes down to a balancing act?

 

I've always thought that tight bends are to be avoided so the path of least resistance is what you are trying to achieve and generally the shorter path would mean less pipework so less mass at the rear of the car but the bore size of your exhaust looks pretty big so presumably this becomes less of an issue and the quality of your exhaust certainly looks top notch. Think I need to do a bit more homework on exhausts unless someone can explain it to me in very simple terms!!

 

Congratulations on a first class project.

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Think I need to do a bit more homework on exhausts unless someone can explain it to me in very simple terms!!

google exhaust science by David Vizard

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Nice work young Brummie. It's just possible you may actually finish this before I complete my Mini!

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Oh my good! This looks really high end! Top quality work all the way!

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