Project Cosmo 20B rebuild thread

Sorry to open up that old can of worms regarding oil in your thread Frank. I have been looking at zillions of threads regarding oil since buying my first turbo rotary, the Cosmo I currently own. Thousands of years ago when I was a young fella I raced a wee 12a bridge port RX2 for about 5 seasons in a sport saloon class which was always run on Castrol GTX. When I first had the motor built for a road car it was a bridge port secondary only which I drove for about 2 1/2 yrs on the road before racing 2 seasons in the same spec. When it was pulled down to make a full bridge port the engine builder said it was mint inside and I continued with GTX after that with no probs. It wasn't till buying the 20b that I worried about putting mineral into a turbo. One of the more interesting threads I found was on RX8 Club which is where I stole the pictures below from. It was mainly about Mazda saying they were supplying a Japanese factory oil when it was a Castrol blend. The renesis is a NA motor vrs our turbo though. The weight also is quite different to some oils put foreward in forums, notably Penrite HPR 30 which is a 20w 60 oil. I currently run a 10w 30 and have put on about 3000 km with it.

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As I said, bit of a can of worms but is always an interesting subject.
Darryl
 
mmmmmmm, interesting stuff, Mazda definately endorses mineral oil as the only option and who are we to argue, lets face it they are covering themselves for any possible warranty claims,,, as somebody who in the past has owned high performance piston engines it was always a given rule that you dont skimp on oil ,,hence why I used Mobil 1, (still have 8 litres sat in the garage) so it goes against all of our past pereptions with a Rotary as our natural instinct is to use the best quality oil we can buy, but if we do then we are probably doing more harm than good.

My engine builder has raced a 20b ( not in a Cosmo) with much success in the past and I know he only uses mineral oil in all his builds, he has been building Rotarys for over 20 years,

as you say an interesting subject, but I will stick with the mineral oil,, anybody want to be 8 litres of mobil 1?(drinks)
 
Ahhhhhhhhhh, the great oil debate!
I recently revisited the oil issue due to a respected rotary engine guy suggesting that the oil I was running was to light. I.E. to runny. Penrite HPR 20, which is 10w/50 After some years of running HPR 30, 20w/60.

Firstly - the factory manual quotes both as satisfactory. HPR 20 has a broader temperature range of applicability as the only advantage. There is a debate that HPR 20 is best used for new engines with strong compression, switching to the thicker HPR 30 when the engine is "older". But how old and when to make the switch seems to be an enormously grey area.

Secondly - other well respected engine builders have told me many years ago to only use Penrite and never synthetic.

Thirdly - pre-mixing. I've been adding 250 mills of a good quality Caltex two stroke for the last four years in every full tank. The plugs have never fouled.

Fourthly - Mazda RX8 oil. I also have PDF scans of Factory documents that state not to use it in pre-Renesis engines. It isn't compatible with the older formulation seals. Essentially the same as above. It's also synthetic. I've only had one engine builder in the time I've been involved with rotors suggest that synthetic oil is ok.

For what it's worth, that's my 10 cents worth! There seems to be a great deal of myth, legend and "belief" about oils in rotors. That's why I go back to the OEM owners handbook and manuals first.

Kramer
 
cosmojc said:
Ahhhhhhhhhh, the great oil debate!
I recently revisited the oil issue due to a respected rotary engine guy suggesting that the oil I was running was to light. I.E. to runny. Penrite HPR 20, which is 10w/50 After some years of running HPR 30, 20w/60.

Firstly - the factory manual quotes both as satisfactory. HPR 20 has a broader temperature range of applicability as the only advantage. There is a debate that HPR 20 is best used for new engines with strong compression, switching to the thicker HPR 30 when the engine is "older". But how old and when to make the switch seems to be an enormously grey area.

Secondly - other well respected engine builders have told me many years ago to only use Penrite and never synthetic.

Thirdly - pre-mixing. I've been adding 250 mills of a good quality Caltex two stroke for the last four years in every full tank. The plugs have never fouled.

Fourthly - Mazda RX8 oil. I also have PDF scans of Factory documents that state not to use it in pre-Renesis engines. It isn't compatible with the older formulation seals. Essentially the same as above. It's also synthetic. I've only had one engine builder in the time I've been involved with rotors suggest that synthetic oil is ok.

For what it's worth, that's my 10 cents worth! There seems to be a great deal of myth, legend and "belief" about oils in rotors. That's why I go back to the OEM owners handbook and manuals first.

Kramer
Click to expand...

very interesting Kramer

I am really interested in how you feel about the two stroke pre-mix in the fuel, do you feel any benefits from it? and does it smoke much?
what about fouling up the back of the car with oil splatters out of the exhaust or is the quantity that low you do not notice anything?
I am tempted to run a tank full with 2 stroke in it just to try it

Frank
 
Frank,
I know a few guys who have been into rotors for a long while who use a little premix for insurance. That's all I'm doing - its not mixed to replace the omp.
Yes I get a film over the rear bumper, but then you get that anyway as omp oil is not completely burnt. Yes I get a bit of blue smoke, happy to have that in a motor with 3 fresh chambers, new eccentric shaft and lots of other expensive bits - insurance as I said.

I'm going to put an oil pressure gauge in as well as a couple of engine builders have mentioned wear in the oil pump as a critical factor in the rear chambers failing. Also, to make sure that you don't go more than twelve months on a fuel filter. Every motor from a Cosmo that he pulls down has a non functioning fuel filter!

Kramer
 
cosmojc said:
Frank,
I know a few guys who have been into rotors for a long while who use a little premix for insurance. That's all I'm doing - its not mixed to replace the omp.
Yes I get a film over the rear bumper, but then you get that anyway as omp oil is not completely burnt. Yes I get a bit of blue smoke, happy to have that in a motor with 3 fresh chambers, new eccentric shaft and lots of other expensive bits - insurance as I said.

I'm going to put an oil pressure gauge in as well as a couple of engine builders have mentioned wear in the oil pump as a critical factor in the rear chambers failing. Also, to make sure that you don't go more than twelve months on a fuel filter. Every motor from a Cosmo that he pulls down has a non functioning fuel filter!

Kramer
Click to expand...

interesting stuff

I am shocked about the fuel filter being a factor in an engine fail, but I will take note and follow your lead on that one,, mind you I have not had the Cosmo on the road for 12 months consecutive yet ha ha
 
Hi Frank
Checked out the clip, sounds sweet. What mods have you done to the exhaust. What km s you up to.
Darryl
 
Cams said:
Hi Frank
Checked out the clip, sounds sweet. What mods have you done to the exhaust. What km s you up to.
Darryl
Click to expand...

Hi Darryl, how are you doing?

the exhaust is a custom made 2.5" full stainless steel from the down pipe back, pre cat removed and fully de-catted, it has 2 very small slim silencers, not much bigger than a motorcycle size silencers so very little restriction,, it also weighs about a third of the weight of the original exhaust.

I have done about 600+ kms so far and now ready to drop the oil and filter, the builder wasnt me to do 1000 miles (1600 kms) before it goes back in to him for a set up and then I can use boost, I want him to restrict the boost until I can get the stand alone ecu sorted as I do not want an over boost situation again as that what took the tip last time,, and I DONT want another repar or rebuild bill

Frank
 
Hi Frank, I'm good thanks. That is a big mod to the exhaust system if you still have a factory ecu. I can see why you would want to keep the boost down.
Darryl
 
Update

just got some new rims and tyres for the Cosmo
19s all round not a staggered fit as I originally wanted but at least I can do tyre rotation if required
this was the last set of these rims as they are not manufacturing these anymore and managed to get a good deal as a result
I have wanted these for a while but have been hanging on,, I am glad I didnt hang on any longer as may well have sold out

still cant make my mind up if the centre spokes would suit it better in gold,, against the red paint and chrome off the rim lips
what do you think?





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This is a link to a video of the cosmo being put away to bed for the day - http://www.youtube.com/watch?v=JGqr0wWTmv4&feature=youtu.be
 
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Wow, Frank...Your Cosmo looks great, I like the stance and the new rims...Thanks for sharing those vids as well!

As for the stand alone ecu, what system are you going to use?

Got pics of the gold spokes?
 
Antoine said:
Wow, Frank...Your Cosmo looks great, I like the stance and the new rims...Thanks for sharing those vids as well!

As for the stand alone ecu, what system are you going to use?

Got pics of the gold spokes?
Click to expand...

Hi Antoine, long time no speak

lookng like it will be a Motech, had a quote for this and the wiring loom, all being well manual box and ECU in September
regards the gold spokes, need to get a phot shot of them in gold before I decide, have left the side skirts in to be painted
so once these are fitted will look at getting the photo shop done,,, then decision time !! Gold or Silver
 
Antoine said:
Wow, Frank...Your Cosmo looks great, I like the stance and the new rims...Thanks for sharing those vids as well!

As for the stand alone ecu, what system are you going to use?

Got pics of the gold spokes?
Click to expand...

Thanks Kramer,, it is starting to take shape now,, slowly
 
Ok it has been a while but the engine break in period is over (headbang)
I have booked her in on Saturday for the 1,000 mile service,, while I am at the garage I am going to book her in for the manual gerbox conversion and the ECU
I also have the bigger intercooler to go on at the same time,, all being well it should be in getting sorted by end of September,, I hope!!

will keep you posted as things develop,, I am off to a rotary meet called Rotorstock next Saturday,, it is held at Santa Pod drag raceway so it has the aded benefit of a lot of street rotary cars having a blast up the strip,, not me though,, been there done that and left a back axle off a 66 GTO at santa pod a few years ago,, and after 2 engine builds on the Cosmo,, no way jose.. I will be watching ,, and poloshing the Cosmo

Frank
 
Cosmo has had it's 1,000 mile service today, therefore now I can use the turbos,, I forgot how nice these cars are to drive when you can accelerate,,
I have been told to watch the boost with the exhaust system having virtually no back pressure the ECU will start compensating and lean the fuel off,, so only giving it little bursts just to wind them up a bit,, still great fun though,, I have got used to shifting manually while I was breaking the engine in and have carried that on as to be honest you use less boost for the acceleration and you can wind the revs up,, good practice for when I get the manual box..

spoke to Pip today and he has been offered a getrag 5 speed with all the adaptor plates for a mazda rotary,, a tad expensive but will be able to cope with 600bhp easy,, so I have told him to secure it for me,, I think the wife is going to kill me (sssh)

he is putting a price together for the gearbox, standalone ECU and wiring loom for the same,, I will get the larger intercooler fitted at the same time,, should be in getting this done in the next Month or 2,, but TBH as long as it is done before next summer I will be happy as it will be nice to use it a bit before winter arrives..

Off to Rotorstock next Saturday,, a yearly Rotary car event here in the UK,, have to show these RX boys what a Cosmo looks like,, had some new number plates made with a little slogan at the bottom,, I have not taken a picture but this is what it says " Eunos Cosmo the true home of the 20B Turbo Triple Rotor " that should upset those RX7 boys that have nicked our engines (evil)

keep watching out for updates,, oh and the car sounds awesome at higher revs,, I will have to post a vid soon
 
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