Dans '81 316 > M42 > Rotary

Dan! · Post by **Dan!** » Tue Feb 21, 2017 7:03 pm

Been busy with work so not much action recently. But today I managed to get a few bits sorted out ready for next week...

I picked up my new radiator, a BMW E36 air con rad. Fit's really nicely in the E21 with minor mods, has a handy built in header tank and I think will offer slightly more cooling capacity than the RX8 rad. Despite being slightly smaller in height/width, it is nearly double the thickness.

Picked up some sheet steel for my new new sump. I've decided to cut the entire sump pan off the sump frame/mount and make a new custom pan, just keeping the original frame/mount section. Sheet steel cost me £3, 2mm thick and cut to size, ready to be bent up and welded. The long part will make up the sides and the large piece will be bent as required for the bottom section.

Also got my rear tyres fitted, slightly larger circumference than the fronts to try and gear it up a bit.

Engine mounts are on order so they should be fitted next week. Also received some D585 uprated coils and magnecor leads for the engine. Got them for a good price and they are a known weak point of the rotary engine, so worth replacing. I know the plugs were done last year so they will be left alone.

Also, I offered up the entire RX8 propshaft and it's literally just 5 inches to short. I'm wondering if it might be easier to use this prop and get a 5 inch adapter/extension piece made up...

No progress made on the exhaust manifold situation but the suggestion above seems like a good starting place, so I will be looking into altering the rack mounts next week too.

uwbuurman · Post by **uwbuurman** » Tue Feb 21, 2017 7:56 pm

Oeh, to bad, that short propshaft.

Dan! · Post by **Dan!** » Thu Apr 06, 2017 8:47 pm

As usual, terrible at regular updates....

I think we last left off when I was making a custom sump so the engine could sit as low and far back as possible. Pictures of said sump during and after...

Sure I took some pictures of it fitted, but I can't find them now.

Made up the coolant pipework using bits and bobs in my spares tub. Not filled with coolant yet as they will all be removed again for exhaust manifold work.

Cut the top off the clutch slave arm so it will clear the bulkhead. Bled the clutch up and it feels good, so hopefully won't have any issues with the BMW master and RX8 slave working together.

Then had the subframe modified, rack mounts extended to shift the steering rack across 15mm and make a bit more room for the exhaust manifold.

Also got the propshaft measured up, decided to just use the RX8 spline shaft and not the UJ. The result is a very short little shaft which just goes from the gearbox to the centre bearing mount, shouldn't have any issues with vibration, hopefully...

And, it's very tricky to get a good picture of, but the standard rx8 drivers side engine mount wraps tightly around the exhaust manifold. See below

So, I decided it would be easier to make a new simple mount up and allow extra room for the exhaust manifold. Pictures of before and after, but again, not fitted, sorry!

So, the big obstacle, the exhaust manifold. I had considered cutting up, modifying, re-welding etc on the standard RX8 mani, but it was just going to be too clumsy and bodged. It will be going to a friend of mine for the exhaust work to be done, but to make his life and the whole task a bit easier, I bought a 3-1 stainless manifold. It will certainly require 2 of the runners chopping and a couple of extra bends/straights welded in, but it should be a whole lot easier overall and will look 10x better.

More on that once it's been to have the work done, on the 15th April...

Lastly, I decided to drop the car down onto all fours again, just to remind me what it looked like as a 'car' and not a pile of crap in the garage. Cannot wait to have it sitting nicely and sounding awesome in a couple of months time.

Thanks for taking time to have a read/look through. As always, comments and advice appreciated.

uwbuurman · Post by **uwbuurman** » Thu Apr 06, 2017 10:32 pm

Wha, lots of working space in that engine bay. Nice progress, but I recommend to make those extended strips of metal on the front subframe more solid. Make it square or weld in some reinforcements.

Jeroen · Post by **Jeroen** » Tue Apr 11, 2017 3:55 pm

Thanks for the update! What's next?!

Dan! · Post by **Dan!** » Wed Aug 30, 2017 5:35 pm

I have to apologise again - I'm absolutely awful at updates! However, the good news is that the car is now running, roadworthy and pretty much problem free!

I really do wish I had spent more time taking photos and documenting the build, for my own reference as much as for my build thread! Anyway, below is a selection of photos and even some videos from the last few months...

The troublesome exhaust manifold situation was resolved nicely

A friend of mine kindly demonstrated the room at the front of the engine bay (minus a radiator and pipework)

The wiring loom was all over the place while I was chopping it, testing it etc.

Mounted an oil cooler. The RX8 has 2 of these coolers, but I'm going with just one for a few reasons... 1. There is basically no space/airflow for another one. 2. The coolers on an RX8 are mounted in triangular grills in the front bumper, they each only have about 60/70% surface area exposed to air flow, this one is fully exposed. 3. Mazda will have almost certainly over-engineered the oil cooling system, this car will not be driven in anger for long periods of time as the RX8 will have been designed for. 4. My water cooling system/radiator is much more effective than the RX8 radiator. 6. My oil capacity is higher due to the larger sump, and the sump is also exposed well to air flow, unlike the RX8's 'plastic-covers-everywhere' design.

My lad tried out the recaros

The final state of the propshaft. The ones pictured previously of a solid front section ended up giving terrible vibration, not from balance issues but from a lack of alignment. The solid one meant that there was no flex when the engine moved and anything above 40mph was a killer. I ended up getting it cut in two and having a BMW rubber 'donut' ring fitted to give it a tiny amount of flex. This has meant it runs fine up to legal speeds...

Did a few bodywork bits with a rattle can. I hate bodywork but it turned out fairly respectable.

When I sprayed the rear panel, I couldn't decide if it looked better with or without the rear plinth

But I ended up decided on with, so got it screwed on and tried out a show plate I bought for it

Got it roadworthy 3 days before I got married

And quite recently, took it to the Rollhard show and a local VW show

And finally, a few videos of the first start, first movement, drive by and in car...

https://youtu.be/Illu_Buzxkg

https://youtu.be/1lz09LG44Ks

https://youtu.be/HQFq9P9zILI

https://youtu.be/7Zhgj2r54K0

I've probably covered 400 miles or so now and there are no obvious issues, other than the lack of compression causing some slow hot starts and a slightly iffy idle/over run. I'm hoping I'll have the funds to do a DIY rebuild over winter to sort it out and make it 100%. It handles brilliantly, no thanks to my homebrew tracking and camber adjustments, which I will get checked by a professional at some point. The engine is a peach in such a light car, the lack of torque which is obvious in a RX8 is nowhere near a problem in the E21, anything above 3krpm and it just goes, it's actually quite scary driving it flat out. I want to try some 0-60 runs/videos soon, It's going to be around 6.5/7 seconds though, by the feel of the bum dyno.

Anyway, there will be bits I've missed out, so feel free to ask questions and offer your thoughts and opinions.

Cheers, Dan.

Wilmo · Post by **Wilmo** » Wed Aug 30, 2017 11:05 pm

At some points during your build I have thought, why o why

but it turned out really nice! Nice to have a small engine further to the back, compared to some much heavier and larger engines! Really a really impressive built.

The pic with your wife really shows the relation 'we' have to our cars ;D