Just cleaning the engine parts up when I came across this dent on one face of the rotor.

First of all is it bad, is the rotor useable? Secondly, what would actually cause this?

thanks

 

was this engine a rebuilt? it looks like some one dropped that rotor because i don't think combustion can caused that unless you where making crazy horsepower.

 

That's a dent from detonation. Does an apex seal slide through the groove?

 

I concur. A dent in the rotor, is either caused by a foreign object entering the combustion chamber, or detonation.

From the pictures you have posted they look to be of detonation. The main problem you have to worry about with this, is although the rotor is technically still usable; that dent well lead to carbon deposits on that spot, which in turn can turn into a hotspot on the rotor, leading to detonation again. Not good. Your best option is to either source a new rotor, or a decent used one that is no more than one letter off from the other rotor you are working with.

 

656cc


=Ben

 

Scrap it, its worthless

 

Is it ideal? No, is it worthless, definitely not. I know of people making near 500rwhp on pump gas with rotors in worse shape than that. That is a noticeable dent but if you are using it in a lightly modded fd, 400whp or less, it is fine as long as there is no damage to the apex seal groove as GoodFella pointed out.

 

I wouldn't use it except maybe in some kind of junker motor. That's a pretty good size dent.

 

So your telling me you would use this rotor in a customers car? I hope not for your sake.

 

Yeah, it should be ok to re-use, although for piece of mind I think I won't.

 

If the customer wants it reused, yes I would. Would I run it in one of the rebuilds I build and sell, no I wouldnt. If you guys only knew what other big builders used it would really open your eyes. I have seen engines from about every shop out there and sometimes it is scary. Hell, look at David's 3 rotor thread, Jesus Padilla is reusing one of his rotors that has apex seal damage, and I am pretty sure he is thought of as one of the highest end builders in teh country, even recommend by Gmonsen

I have a customer who I rebuilt his engine for him back in April/May of last year who had a rotor dented similar to that, due to being tight on funds he wanted to reuse it. He has put about 7-9k miles on the car at this point as it is his daily driver and he has had absolutely no problems out it.

Once again, is it ideal? No, do I use parts like that in my builds? NO. If a customer sends me their engine and wants to reuse a rotor like that will I, sure it is their engine. Will it effect anything on a car that is making 400rwhp or less, nope.

If everyone had the money like you did to replace new housings/rotors/irons every year rotary shops would be a lot happier. In a perfect world every customer would buy a new wiring harness($800.00) New injectors($900.00), New Housings($1200.00) and new Irons($1100.00) during every rebuild. But when you are dealing with a car that is worth $9-13k most people dont want to spend $6-8k on a rebuild.

 

I would NOT use it in one of our performance motors and wouldn't offer a warranty. While it will work, the combustion may be uneven and cause hot spots. I believe that is one reason I kept pinging on the same rotor many years ago. Couldn't find anything else wrong. I wouldn't use it on anything except a budget no frills rebuild, which I do not do.

 

It is now a paper weight....get a known good one.



Later

 

Logically thinking this dent would make bigger chamber, you would get more cc. While injectors would be running same duty cycle, this chamber would have leaner A/F ratio compared to other two, so while gaining HP this dent might lead to another detonation

 

I'm not going to be running anything more than 400bhp atw, so it should be ok?

This is a budget rebuild, so don't want to spend if I don't have to.

If this happened in an engine, what else would it damage as everything else seems fine. The engine did fail though... A little water was found in this housing. No other evidence of failure.

Is it possible for this to somehow take out a water seal without actually damaging the end plate or the apex seal?

 

This didnt cause the water seal damage, the compression ratio on that face has been slightly changed. It will run fine in your engine, but as I said, it isnt ideal. I can sell you a good rotor for $220.00 Shipped to Scotland if you can afford it, but if not you will be fine running this but not recommended.

 

Can I ask why it's not recommended although it should be fine to use?

 

Just saw this. To clarify, my rotor didn't have a dent in it, it had a small gouge (maybe 1/4 inch) caused by the ceramic apex seal. Jesus repaired this by smoothing out the gouge. The dent in the rotor in question is pretty big and I would have had Jesus replace it.

 

That was offered above:

If you are going through the trouble to rebuild the motor, I would at least try to find a usable used rotor. You might find that a good used rotor a lot less expensive than you might think.

 

i don't think the displacement changes, but the compression ratio would be slightly lower.

 

djseven:

displacement wont change. the rotor will displace exactly the same amount it normally would. but since the chamber size is slightly larger (very slightly) the compression ratio changes. But not displacement.

 

That is exactly what I said above Maybe you misread or confused someone else's post with mine? Either way, since it was a water seal failure and the apex seals werent damaged it is likely this engine ran this way for several thousand miles, of course I dont know the history of the engine.