We opened our racemotor today, it had no compression on the front rotor.

It seems like a rotorbearing had come lose and the rotor have been touching the housing.
www.wankelkim.net/rx7/fb/badpphouse.JPG
I know this housing is fucked up and will end its days as a fishtank.
We have this other housing that had similar damage, but not as bad as that one.
it looks like the rotor has been in touch with this one too, the scarred section is about 0.2mm deep and something like 25mm long.
www.wankelkim.net/rx7/fb/damage.JPG
Im pretty sure that we can make it kindda flush again and it being located between the intake and exhaustport it shouldnt affect compression, right?

Am I right or are these housings fuxxored ???

Kim

BTW what caused that fish-scale like "Cracks" ?

More pics of the car: www.wankelkim.net/rx7/fb

 

bump

 

That second one doesnt look horrible. Is the chrome peeling/flaking off?

What did the apex seal's out of that housing look like?

Where that is I wouldnt think it would effect compression, could cause a number of other prolems depening on how bad it is. Do you have any other photo's of this housing?

-Jacob

 

This damage can be from a brookend stationary gear,so if you going to rebuild your engine look after cracks on your gears.

/Jörgen Blennow
Sweden

 

Thanks Jörgen, I will check that.

BTW have You ever build a motor for Alex Buch Larsen or Hans Vestergaard?

 

No!!
Alex had two engines and both was sold to Sweden, one of this (sprint engine) is still here and is in Mohlins racecar.I dont know where they sold the other one,but maby it's your engine.Alex had problem with brookend gear and i rebuild the engine that Mohlins have with new MFR Housing and stationery gear.

 

man, what did you do with that engine ??
high rpm??

 

I didnt do it, they were like this when we opened the motor, We havent driven the damn thing yet. fortunately I have a Bridged 6port waiting to go in, so that we atleast can get some tracktime while we fix the MFR motor

 

I am concerned about all those micro-cracks in the surface.
Is the hard surface plating cracking? Will those cracks get worse and start flaking?

If you smooth out the rough spot, you will leave a low spot right there. Can you get the apex seal to seal properly as it passes over that low spot? Even though the rough spot is in the area between the intake and exhaust ports, there will probably be enough exhaust pressure in the lower rotor chamber to blow through under that low spot, and dilute the intake charge in the adjacent upper chamber that just picked up a fresh intake charge. This diluted intake charge would reduce the power that rotor could make.

A popular alternative here in the USA is to make peripheral port housings from new stock housings. Cost is about $300 to $350 for a new stock housing, and PP labor cost is another $300 to $500 per housing. This would give you a brand new PP housing for about $600 to $850 US dollars each, much cheaper than the $1800 each cost for Mazda Factory Race PP housings. When made from new stock housings, and when they are made by a very experienced Mazda race engine builder, these housings are just as reliable as MFR housings.

 

Thanks Jorgen,
Both stationary gear look to be in perfect condition. The problem, I think ( I am talking about the front rotor, the rear rotor looks good) is the rotor bearing with relation to the eccentric shaft, shows signs of abnormal abrasions and wear. I also noticed no locking screw used for this bearing but remember seeing 2 tapped threads. Perhaps Kim removed them and I did not know this? I need to look again and will post a photo.
The front rotor showed zero compression compared to the rear which had 4 bar. All 3 side seals on the front rotor showed no movement ( locked down) and I think the outer rotor surface to the housing has extensive wear, I'm not sure?. Again, I will try and get some photo's so you can understand what I mean.

//Oliver

 

Tom,
Those micro cracks are everwhere on the front housing. You need to get some good light to see them. They really show up in the photo's using the flash from the camera. You can see the mico cracking but not feel them, only the small area that was damaged from the rotor shows flaking. We also have trailing spark plug cracks over 8mm. It's a real shame because the porting on these housing are VERY nice.

Haven't had time to check for clearence... The minute we saw the conditions decribed above, we were pretty disappointed. Appreciate the prices and information Tom. MFR housings are just out of my price range so we will need to purchase new stock housings and might do our own porting since I have correct equipment at work.

Like Kim said, we have another motor which will give us some needed time to learn the race car and prepare for the PP.

//Oliver

 

/dumb kinda-newbie question
The coating on the inside of the housings and rotor faces is chrome isnt it? Or at least something that is commonly coated on the inside of an engine (any engine, not just rotaries). Why cant it be removed and recoated???

 

The factory PP housing is made without steel inserts so the chrome is directly on the aluminium housing thats why they got all this micro cracks on surface.We have run with housing that looks like this without any problem and all MFR housing cracks like this when the are used so dont worry about them.

 

Can you send me some good pics on you housing so i can se how it looks,last year Mohlin run with housings who hade some dents from rotors who had touch the housing.The main reson why it looks like it does is probably high rpm.Im going to talk to a friend who is working with termic coating about some coating on my 20B engine so i can talk to him about this housing.Is it possible that you can send me your housing to me so i can show him them??.

 

i dunno why u would get cracks like that. high temps maybe?

 

I have a set of used MFR 13b housings and they done show any cracking like that.
matt

 

Lucky you !!!! They will start cracking when they are old and well used.

 

Has anyone ever tried having the housings replated with Nikasil or a TiN coating?? I'd be interested to see the results.