tips on building a high rpm motor

[My5ABaby]

http://www.rx7club.com/showthread.ph...ighlight=crank
http://mazdarotaryclub.com/forums/sh...ad.php?t=34296

I'd also seriously put on a scatter shield...

[j9fd3s]

Originally Posted by IH8DSM

I got a s4 so I guess it'll be ok, what's your opinion on reusing tension bolts vs buying new ones or studding it fczach and I have went back and forth on this topic

mine is a 12A, and i wanted to use studs, but at the time we couldn't get em short enough, the 20mm between a 13B kind of matters if you want to use a flywheel...

so anyways i just used stock 12A bolts and did the RB silicon thing.

the problem with stock bolts is that they hit a resonance in the 9K range, the factory fix is a bit of rubber in the middle, so the RB silicon should work just as well. no resonance = no problem

-mike

[RETed]

It was a really good thread up until the last few posts.
Please keep the good discussion going and on topic.
Thread cleaned.


-Ted

[My5ABaby]

http://www.summitracing.com/search/D...?Ns=Rank%7cAsc

I'd also check with Racing Beat and see what they say. Atkins is currently selling a drag 1st Gen that has one on it so you could ask them how they did it.

[j9fd3s]

Originally Posted by My5ABaby

http://www.summitracing.com/search/D...?Ns=Rank%7cAsc

I'd also check with Racing Beat and see what they say. Atkins is currently selling a drag 1st Gen that has one on it so you could ask them how they did it.

i think i'm going to go with a blanket. i know this is kind of cheesy, but on a 1st gen the flywheel is actually pretty far ahead of the drivers feet, so its not like you're right in the line of fire.

on something like an Rx3, the drivers feet ARE in the line of the flywheel, so its a bigger deal

i'm not sure about the FC, i've had all 3 (Rx3, 1st gen, and FC) in the driveway, and the Rx3 was actually the longest (fc is the smallest), the Rx3 has the driver further forward than the Rx7's

[IH8DSM]

I've been thinking at blankets for awhile now but just haven't followed thru

Rb silicone hmm I'll have to look into that( never heard of it).

Not sure what you had to clean up Ted but thanks I'm learning a lot from this thread

[RETed]

Originally Posted by j9fd3s

i'm not sure about the FC, i've had all 3 (Rx3, 1st gen, and FC) in the driveway, and the Rx3 was actually the longest (fc is the smallest), the Rx3 has the driver further forward than the Rx7's

Ask Paul about his getto clutch hook-up and his FC...
When the clutch disc let go, one of the pieces took out the clutch slave cylinder on the bell housing.
You can get an idea where that will lop your legs off by the clutch slave cylinder position now?
He's lucky!


-Ted

[j9fd3s]

Originally Posted by RETed

Ask Paul about his getto clutch hook-up and his FC...
When the clutch disc let go, one of the pieces took out the clutch slave cylinder on the bell housing.
You can get an idea where that will lop your legs off by the clutch slave cylinder position now?
He's lucky!


-Ted

so you're saying before we haul peepers up to sears point for Wednesday night drags, i should do something?

-mike

[NoDOHC]

Check the clutch speed rating, if you intend to rev past the rating (or even to it) you should have a scatter shield.

Mine is rated for 9500 RPM. This is a pretty typical rating for a performance rotary clutch. You can get a better rating for NA drivetrain. 9500 is about it for turbo drivetrain.

Also, check your alternator (you may have to underdrive it), I ruined my s4 alternator by turning the rev limiter off, forgetting that I had, and trying to see how fast I could go in first gear. The fan belt broke at about 52 mph - about 10,000 RPM (because the alternator had seized).

For future reference:
I have run my engine for 3-4 hours on the dyno on several occasions with no issues at 9500 RPM. I had to do a teardown about 6 months ago due to thermal expansion in the spark plug area killing two apex seals. When I tore the engine down, the bearings looked like they were brand-new, the rotors had not touched the housings, the engine was in excellent shape with the exception of the blown seals (which really didn't do much damage, as I was able to re-use the rotor).

I have an 88 TII engine, stock planetaries, stock rotors, stock counterweights (using auto-trans counterweight in the back) stock oil pump, stock oil pressure regulator, and thermal pellet in operation.

The rotors have been clearanced, polished and lightened to 4.2 kg and the rotating assembly has been balanced with these rotors. I am running 15W-50 Mobile 1 synthetic oil.

To clarify - I only revved to 9500 RPM in second gear on the dyno, as the engine would overheat before I could get there in 3rd or 4th, thus the engine wasn't running at high speeds for extended periods of time.

Last time on the dyno, I made peak power at 6800 rpm (mild street port). This makes the 9500 RPM rev limiter seem a little like overkill... You might want to make sure that your porting supports making power at that high of speed before you spend a lot of time and effort worrying about it.

If you are turning that fast, You should definitely make the modifications that everyone suggested above (especially hardened planetaries and balancing). I merely posted what I have gotten away with so that you have some peace of mind.

Spark notes version:
Check clutch rating
Balance engine (absolute must)
Verify porting supports higher speeds
Even semi-stock rotaries will handle high speeds for short bursts

[j9fd3s]

Originally Posted by NoDOHC

Even semi-stock rotaries will handle high speeds for short bursts

yep. also the stuff that they outline in the competition prep book (www.foxed.ca) from 1979, has eventually become standard on the street engines.

the FD engine has the hardened gears, multi window bearings, high oil pressure, oil pan for corners, etc stock.

the Rx8 has the side clearanced rotors. which is applied retroactively, so if you buy new FC/FD rotors, they come side cut too

-mike

[FC Zach]

And also, make sure your drivetrain is bulletproof. And no matter how solid of a drivetrain you think you may have, you'll have to accept the fact that it won't last long. Ask me how I know, I just blew my fourth trans tonight, the latest being a JDM S5 T2. Even though it outlasted all the others combined I knew that one day it too will go and its life ended tonight. RIP tranny

[IH8DSM]

figured id update this i havent forgot about a nice na build

Originally Posted by IH8DSM

-s4 turbo motor ran as a na bridge ported(used housings/irons)
-s5 rotors
-race rotor bearings -
-rx8 eshaft
-rx8 front and rear stationary gears
-cryo treated 2mm apex seals atkins
-cryo treated side seals atkins
-solid corner seals
-new apex seal springs, corner seal springs and side seal springs
-aluminum light weight flywheel
-rotating assembly balanced

figured id add to this
- turblown studs (zachs gonna yell at me for this one)
- oil pan baffle
- shimmed front cover/ shimmed rear opr
- turbo2 oil pump
- studded oil pan w/brace
- some kind of transmission blanket/ scatter shield

figure thats enough for now a lot of parts have been ordered already so hopefully i can start porting cleaning and finish gathering parts to where i can build me a motor after christmas.