Motor Swaps

niall · Joined: 06 Sep 2007 Posts: 153

The car is a 1979 Bmw 323i. Originally it was a 2.3 6 cylinder 4 speed with a 3.45 diff ratio, kerb weight is around 1100kg, this set up was probably good for 90-100 rwhp i estimate. The car then had a 2.7 block with a big port head and larger throttle body, this set up probably made a strong 120- 130 rwhp. The 2.7 was sold to another e21 owner as i wanted a more powerfull engne and 5 speed gearbox. I was initially swayed towards a m30 3.5, then an m60 4.0 v8, even a rover v8 had crossed my mind. finding clutches/flywheels and suitable manual gearboxes made most of these swaps too difficult.

i decided to rethink my engine choice. i realised that for street use with small tyres getting power to the ground would be difficult. I realised i would need an engine with little low down torque but high power and torque higher in the rev range. Turboing a bmw engine was an option but would not be as good as using an engine designed for turbo'd use. I prefer 6 cylinders to 4 cylinder engines because they are smoother and better balanced. closer power pulses mean that a lighter flywheel can be used which helps it rev even more.

I knew then that the Rb20 was the engine for me, cheap an plentifull because they are not as popluar as the rb25 or the Sr20. Browsing the forums i found a suitable conversion package for a good price so i bought it.

the car when i got it.

then after a few mods

First thing i did was dummy the engine into place to see if any modification was required and if the shifter location lined up somewhere near the factory location.

Engine mounts made.
I overkilled a bit and used 8mm steel plate with a 5 mm gusset. all the 8mm was seam welded but i just stitch welded the gusset in.

I made these mounts with no special tools at all apart from the use of someone else's mig welder. I could have got the plates laser/water cut but i decided to do it all with the angle grinder to show all you people who dont have access to a workshop that these things can be done. and here's how.

First i spoke to the mod plate engineerand showed him a few sketches, got the nod so then i rang up a local steel merchant. got 8mm plate 200mm wide x 800 long. I only used about half of that but i wanted leftovers.

Back to the crib armed with a 4 inch angle grinder, 4 1mm cutting disks, a grinding disk and a sanding disk. Grabbed a cardboard box and a stanley knife and started cutting it to suit, go all the peices in place, then transfered the cardboard to steel. cut them out and grinded them a bit.

I used a little arc welder to tack them in place. only a little 100 dollar jobbie. then took the plates down to the mig and welded them up. if you cant weld em a blacksmith or engineer would do them for under 50 bucks id say. then primed and painted them

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niall · Joined: 06 Sep 2007 Posts: 153

i dropped the donk out again. to do the final remodelling on the firewall and to bolt the box to the engine for the last time. i cleaned up the lower engine bay and sprayed some single pack matt black around. I havent chosen the final colour for the car yet but either way matt black in the lower part wont be an issue. i then cleaned down the crossmember and painted it too as it was starting to rust on the surface.

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niall · Joined: 06 Sep 2007 Posts: 153

i got the head back today so i dummied it on the block and chucked on the manifolds and turbo's, now this is only a pre assembly just to see if everything fitted.

im really happy with how everthing fits, i just need to remove the battery tray, relocate a few pipes and ill heatsheild everything around the turbo

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niall · Joined: 06 Sep 2007 Posts: 153

heres a quick sketch i did in paint of the gearbox mount i would like to use, it will be made from 8mm steel plate which is very strong, so i am not sure if i will need the 5mm gussets on the underside , there is only 1 drawn in on the pic, the light grey triangle. but there would be 4 if i decided i need them

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niall · Joined: 06 Sep 2007 Posts: 153

well i actually got a bit done today in between all this internet posting. since the gearbox is up where i want it i did a quick pre-assembly of the shifter and interior bits
heres some pics
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the gearbox on a jack, but up where i want it. you can see the standard nissan rubber mount on the gearbox and the recess where the studs are coming out, thats wht my crossmember is reduced to 40mm in the middle
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the nissan crossmember, wrong shape so i cant use it, very thin metal too.
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the gearstick is quite tall but i am going to keep it that way for the moment because it is nice and close to the steering wheel. The box has a very short throw standard and a positive feel because it is direct into the top of the box, not through a linkage arrangement like my old Getrag
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this is what it will be like put back together, the interior wont win any awards thats for sure.
It doestn look very BMWish but i gues its not anymore....
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niall · Joined: 06 Sep 2007 Posts: 153

project for tomoro.

This is the front balancer for the RB20 of course, the furthest out pulley is for the A/C which has been removed so i am going to mill the pulley off for extra clearance.

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niall · Joined: 06 Sep 2007 Posts: 153

Well i have really been getting into this project lately, i put in a long night last night and a full day today. On the agenda was

1. Remove interior
2. Remove sound deadening and foam stuff
3. Relocate battery to Boot
4. Wire and test all electrical systems

Removing the interior did not take very long, i needed to remove it for a few reasons, th run the main power cable through the car, to remove all the sound deadening material and to drill and mount the gearbox plate.

I removed about 40kgs of material from the interior that will not be going back in so it will be interesting to see hwat the final vehicle weight is.

The cables i used are genuine jaguar battery cables which are rated to 1000 amps. i have got but not yet fitted a 500amp fuse right at the positive battery terminal which will blow if the main power cable goes to ground anywhere up to the front, this is very important to prevent electrical fires on a main cable like that.

I also used a genuine jaguar power isolation stud as the main power distribution point up on the inner guard. this allows a solid insulated mounting point which is close to the starter motor. i then used some smaller power cables to go from there to another distribution point beside the factory fuse box for the power wires that were connected to the battery in its previous location.

The process then began of finding suitable earth points on the engine and body, filing the areas and mounting hardware back to bare metal , once i was done i checked each one for resistance and then resistance from various parts of the engine and suspension to the body.

Before i connected the battery i checked witht he multimeter that no part of the power sstem had continuity to ground, and when i connected the battery there was now sparks at all.

I checked the operation of all the lighting systems , horn , wipers etc. everything worked.

The orignal engine harness was removed very easily with jsut one plug leaving just the body systems in place. I then connected the starter motorand checked the wiring diagram for the small signal wire to the starter then becomes live when the key is switched to position 3. That was easily found and connected. the starter spun into life very quickly with a good positive engagement.

Now the pics.....
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The battery in the boot. not mounted finally yet as i will be installing a battery box and a few other items.

One of the main power cables . including insulation the outside diameter is 14mm!

The interior stripped and ready for new carpet

The power distribution stud. The other side of it is identical and the 2 nylon parts are the only bits in contact with the body
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niall · Joined: 06 Sep 2007 Posts: 153

here's some port work i have done,

What you can see here is the sandwich plate between the cylinder head and intake runners. Originally this housed butterflies which opened and closed some of the intake runners to boost low rpm torque.

On my engine they were mostly seized up and damaged so they are being punted. The butterflies and shaft alone cause quite a restriction so removing them will improve flow. then i noticed the lip and sealing area around the plate, this should be removed too. here's what i ended up with

Before

after
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niall · Joined: 06 Sep 2007 Posts: 153

Well i really go stuck into it today. got the head from the machinist around 9am , so i went home and got the die grinder out to match the ports to the inlet manifold that i ported out a bit. Then i started cleaning and blowing it all out. i cleaned and installed the bucket lifters - cam and then cam caps. each cam turned over nicely. so i set up each cam and turned the engine over to the timing marks.

Then i installed the head with a new OEM headgasket, torqued it up, fitted the waterpump, cam belt and idlers then the lower cover and cam covers
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niall · Joined: 06 Sep 2007 Posts: 153

The exhaust was the job for yesterday. To save time and to have it quiet for the transport inspection and roadworthy i decided to marry up the 2.5 inch single downpipe into the rest of the factory 323i system just after the gearbox. The details of the engine are sketchy so i dont know if it had a CAT from the factory. the downpipe went half way along the car, so i think it didnt.

The exhaust is a bit lower than id like it, but i dont know how much clearance it has, when it is all put back together ill measure it and try toi raise it if i need to.

As i have said in earlier posts, i am installing the engine witht he intention to run it at a very mild spec to begine with as it has been not running for a long time. so once everything is legal and running nice, then i will make a single 3 inch system to go witht he other mods i have planned.

you can see in this pic, the single front section is the nissan pipe, the coloured piece is a 3 inch stainless pipe with some sort of coating on it and the 2 rear pipes are the factory bmw pipes

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