mr g lord focker

If I wanted to get 3mm apex seals for my FD would I have to mod the motor at all to be able to accept them or will a stock port FD motor be able to take em? If any mods are needed, what are they and how much $$:?

FormerPorscheGuy

I don't think any direct machining is needed, but you will have to completely disasemble and rebuild your entire motor to do so.

jimlab

You will have to have the rotors machined for 3mm seals. Cost can range from $200-300, give or take.

Here's some good information on apex seals...
http://www.scuderiaciriani.com/rx7/apex_seals.html

maxpesce

The Apex Seal slots in the rotors need to be remachined to fit 3mm seals - the ONLY reasons to add 3mm seals is to reuse rotors w/ excessivly worn apex seal slots or run 22+ psi of boost
Rotary Aviation has recently introduced a new very high strength 2 piece 2mm apex seal that suposedly eliminates seal brakage due to detonation.

radiantRX-7

iTrader: (1)

Dave at KDR could mill your rotor's for you.

911GT2

Any machine shop can mill out the seal groove to 3mm. It should take like a total of a half hour, and 20 mins of that is setup/programming if it's a CNC machine.

But as others have stated, you'd need a reason to want to do this. So unless you plan to be running crazy boost on that motor, theres really no point.

poss

iTrader: (5)

Don't make it sound so easy unless you've done it...cause it's not a 30 min job for a shop that's never done it before, at least a high precision job anyway.

RonKMiller

Agreed. I would never dream of taking them to just any shop since they will most likely mess them up. A job like this is dependent on the skill of the operator in setting it up - if it's not absolutely perfect you'll ruin the rotor - and an engine. The worst part is you won't know until its all back together and running. VERY tricky machining.

Unless you know the shop has done this multiple times before you're better off buying new OEM rotors and staying with 2mm.

911GT2

Ok well I haven't done it, but I've used manual mills, and CNC mills, and both can be very user friendly. If someone who uses one of these machines daily can't enlarge a 2mm groove to a 3mm groove, while keeping the center of the groove in the same place (which is the only "trick" to machining the grooves that I can think of) then he or she should not be a machinist.

Maybe I'm missing something...

Brian7

A 3mm seal will be more forgiving to detonation/poor tuning will it not?

Any word on cost, or the name of someone on the board that has them?

jimlab

The precise tolerances required. It's not "just" a 3mm groove.

Throw a set of Ianetti ceramic seals in a "3mm" slot and see how long they last. Hayes Rotary did exactly that by substituting older 13B rotors which had 3mm slots already (effectively pocketing the "machining" fee I was charged) in my engine and another built at the same time. Mine never ran before the problem was found, but the other owner wasn't so lucky. His ceramic seals bound up and cracked (at ~$300 each) in the first 500 miles of use. Mine had several other problems when it was opened back up, but obviously a "3mm" slot is not necessarily all that it takes to install 3mm apex seals.

Barely. Read the information at the link I posted above.

mr g lord focker

brian7...go to rotaryaviation.com. They are however sold out until late Feb. Thanks for info guys...going 2mm. Running 14 pounds so i figure not needed from what I have heard