FD3S_wanted

iTrader: (5)

Hi guys,

I'm rebuilding my 13B-REW engine. I would like to re-use the rotor housing however I'm worried about some micro-cracks around the spark plug holes. There is four tiny cracks on each spark plug hole (north, east, south, west) that are almost not visible when looking quickly.

Please see pics in attachment. What do you guys think? Is it considered "normal" and re-usable?

Thanks.

Alex

RotaryEvolution

iTrader: (30)

don't lose any sleep over it. if you're really concerned then buy some used low mile housings that don't have the cracks, they will eventually crack though under your nose.

FD3S_wanted

iTrader: (5)

Thanks.

Is it possible that the engine compresses in the cooling system via those cracks?

Jeff20B

iTrader: (13)

Nope. They're too small.

RotaryEvolution

iTrader: (30)

even larger cracks i have yet to see make it all the way to the coolant channels. generally it is just the steel/chrome sleeve that is cracking anyways.

blmcquig

iTrader: (15)

yeah, as Karack said, dont loose any sleep over it. ive built a couple engines with small cracking around the spark plug holes, and one is still fine, the other let go due to oil issues...

GoodfellaFD3S

iTrader: (213)

That's not horrible.... I've seen much worse. Much larger than that and I wouldn't be too comfortable using them. I've heard (from another engine builder) of the coating peeling away when the cracks get very bad, but never seen this first hand.

Typically the worst cracks are from cars that are tracked or driven hard with insufficient heat range spark plugs installed. IE using standard bur9eq's for 20 psi on the street, or even less boost on the track. I typically recommend proper 'race' plugs (greddy/ngk) for applications above the aforementioned. Notice i did NOT say 'b10eix, b10egv' etc snowmobile plugs

RotaryEvolution

iTrader: (30)

it's really just caused by heat, the more heat the engine generates the more the cracks will show and grow. so yeah, cars that see the track often and higher modified engines usually will get the cracking earlier than cars that aren't abused much.

the non turbo engines almost never had any cracking issues even with the thinner chromed housings.

i have yet to see the cracks cause any real issues but they could potentially leave a hot spot for preignition if it is bad enough.

GoodfellaFD3S

iTrader: (213)

Boost does cause heat, and lots of boost causes lots of heat

RotaryEvolution

iTrader: (30)

that it does

Jeff20B

iTrader: (13)

Here's a maybe-related heat question. Competition oil jets swapped in the shaft for cooler rotors? Anyone ever used these?

GoodfellaFD3S

iTrader: (213)

Those won't affect the issue we're speaking of.

I believe those jets are not acceptable for street cars that operate at low rpm moreso than high rpm.

RXvedub

iTrader: (1)

the cracks will continue to grow so its best to get new housings.. Then modify the water jackets to improve cooling in the spark plug area to prevent this from happening again. my motor builder did this to my turbo motor.

RotaryEvolution

iTrader: (30)

+1, will keep the rotors cooler but not the hot spots on the rotor housings. i did run modded oil jets a number of years ago and the oil pressure was a bit lower than i really liked to see in a street driven car.

Jeff20B

iTrader: (13)

Ok thanks. I just figured since my shaft already had them, they'd limit the possibility of cracks forming once I go turbo. But you're right about the oil pressure. I hate seeing only 14psi at idle. I'm thinking about a quickie rebuild just to change the jets to the checkball type. My mistake was not checking the shaft before I used it. All modern R5 shafts have them is what I've discovered. Who knew?

RotaryEvolution

iTrader: (30)

if they are in anything over a 2 rotor, ditch em for sure.

Jeff20B

iTrader: (13)

Agreed. The 4 is getting small checkballs and matching long screw caps from some early 12A shafts. Figured big ***** found in later engines with high volume oil pumps would be a bad idea.