he's using a hammer and a hacksaw in a garage...

 

When I built the electric Geo I had a machine shop make a "dummy crank" that is just a piece of round 4" long and it had the crankshaft bolt pattern on the end of it. I had them turn the flywheel all the way down to the OD of the pressure plate. I didn't need the ring gear or the weight. I then popped the dust seals off a pilot bearing, dried it out, oiled it with a light weight oil, and placed it in the flywheel and then slid the bearing over the input shaft of the trans so the flywheel was free to rotate. The heaviest side came to rest at the bottom and I drilled holes in it until it was neutral. I was very surprised how sensitive it was to small changes in weight. I then drilled 2 holes to glue in small magnets that triggered a small pickup coil (taken from a relay) to drive the factory tach. This is the same way we balanced the prop on my friends hovercraft. The Geo motor/flywheel spun smooth as silk at 8000rpm.

I can have a machine shop mark the radius of the PP bolts on the flywheel and if they are all drilled equally it will have little effect on the balance.

Never underestimate human ingenuity. I wish I had the space for a mill, lathe, and, oh I don't know, a laser table? Ah... maybe some day.

I've helped a lot of people over the years and have many friends I can count on to knock out a part here and there. My intake manifold, for example, won't cost me anything but the cost of the flanges to be jetted. In that example, the gaskets will be scanned to DXF and the laser/waterjet guys just slip the DXF into their nest. Very reasonably priced if you do it that way.

 

Come on, Noah only had a mallet and chisel, and he built an Ark

 

I know you guys love these graphs but I never actually compared the Solstice AR-5 to the RX-8 6spd. I like that .73 overdrive but it's a stump puller in first and second. I'm going to have to look into diff gears in the near future.

Solstice---------RX-8
3.75-------------3.76
2.26-------------2.269
1.37-------------1.645
1.0--------------1.187
.73--------------1
na---------------.843

First pic is the 4.44 rear. Second is a 3.50 rear just to see how low it would need to be to get a redline shift to equal the RX-8 in first and second. It put a 75mph cruise at a much more respectable 2400rpm vs. 3100rpm if I kept the 4.44.

 

It's my understanding that the RX-8 R&P can be used in an RX-7 (8"). So rather then look for RX-8 info I looked up RX-7 info. I found a lot of it. Apparently the Mazda 929 gears fit in the RX-7's housing. I shall assume that they will also fit the RX-8. I found a list of these ratios but can anyone verify this information about the 929 gears fitting the RX-8 diff?

Diff ratio 929

929
1986-
Manual
2.2i 3,909
2.2 3,727
2.0i 4,100
3.0 3,583 leaded
3.0 3,727 unleaded

Auto
2.2 3,909
2.2i 4,100

1989-
Manual
2.2i 3,909
3.0 3,727

Auto
2.2i 4,100


B2200 MT / AT 3.909
86-88 RX-7 5-spd 4.10
86-88 RX-7 GXL 4.10
87-91 RX-7 T2 4.10
89-90 RX-7 GTUs 4.30
86-88 RX-7 Auto 3.909
B2600i MT / AT 3.727
B2600i 4x4 MT 4.300

 

dude.. no offence but you are a swirling mass of negativity... you have no idea of what tools/equipment/level of fabrication skill this dude has but yet you sit perched like a spidermonkey ready to sling **** with both hands at every opportunity...

if his pending swap offends you so greatly why don't you just stop posting in his thread??

FYI to balance a flywheel you need either a lathe or if you wanna shade tree it build some apparatus where the flywheel is held horizontally... you'll see which side is the heavier... remove metal from heavy side till you achieve a static balance... *(this is a gross simplification of how to do this... it must be done very very carefully as its easy to remove metal but a bit more difficult to add it back..)..

a simple google search will help clear your confusion... here

point being its not rocket surgery...

 

You have to dynamic balance a flywheel... the engine isn't static. Just like you balance wheels. It's not as easy as you make it look.
I'm just pointing out his flaws but he thinks to know better than all of us combined.

That's how you balance a flywheel btw:

 

Also fictional. Good parallel to draw.

 

yes..... re read my quote.. i specified static balance... i also know a thing or two about dynamic balancing and the need for it...

i also know dynamic balancing can be done WITH CARE at home in a garage....
*(we do it all the time with motorcycle wheels)....

the main thing i am saying is you shouldn't **** on the skills and abilities of people you don't know... i have no idea what you know or what you do for a living... you could be a master machinist or a janitor... but i won't chop on you for the simple fact that i don't know...

the OP could be a genius or completely full of ****.... i don't know buy i will wait patiently to find out without bashing him... or you... or anyone else...

*(btw i am a mechanic for a VERY large airline and work in the miami international airport....)

good day..

 

Motorcycle wheels are one thing. A flywheel, with a integral balance built in, is different. I had a flywheel come back from being resurfaced (on another car) that was not balanced correctly. It was un-driveable.

 

hate to argue but they are the same principle... i don't know how much experience you have on 2 wheels but i have enough for the both of us.....

on a modern sportbike capable of 187+ mph and doing a 9.5second 1/4mile off the showroom floor the wheels/tire balance is critical.... *(i will concede that a flywheel spins at a MUCH higher rpm... but if your flywheel is out of balance it won't make you wreck and slide down the road on your ***/head/etc.. you'll *** up your bearings/seals/transmission/check book..)

MY POINTS ABOUT THIS ARE SIMPLE....

a. you can balance a flywheel at home..

b. never belittle anothers ability when you don't have first hand knowledge...


that is all i am trying to say...

 

Mazda has a few rear differentials.

the Rx8 has the P type diff, which uses an 8" ring gear, its shared with the FD (Rx8 and FD use the same part number ring and pinion), the 929, MPV, etc

the non turbo and 4 cylinder cars use an M type diff, which is a 7" ring gear, its used in the 1994-05 Miata, 1970-1992 non turbo rotary cars, and SOME of the trucks. also the S2000, which is why its fragile, honda put it in a car with 100hp more than Mazda has ever done.

SOME trucks use an oddball 7.5" thing, and the 94+ trucks are ford. i'm not sure what the new miatae use, as they have different part numbers

the 1988 929 MANUAL TRANS, has the tallest gear, 3.7, but its a RARE car. the AT 929 is 3.9, so basically the tallest gear is 3.9.

the 3.5 in your chart appears to not have made it to the US

 

Thanks for the input. The 3.5 in the chart is simply a value not a production r&p. A 3.5 ratio puts the v6 redline at the same MPH in first and second as the stock 8's ratio with the rotary redline. The Mazda 3.727 ratio would work if I can find it.

I understand how balancing works. I used the Geo as an example of how I was able to perfectly balance a flywheel in the garage. I either got really lucky or I know what I'm doing. Most of us know that even the factory balance is never perfect and this isn't a 14,000rpm race engine either. It's an old truck engine that's being converted for use in the RX-8 and the only argument in question concerning the flywheel was that drilling holes to mount the pressure plate would require rebalancing the flywheel. Even if the holes were off by a few .001s it's not going to hurt the balance. The flywheel is probably further off balance from the factory then 6 symmetrical holes would cause.

The most important thing I have yet to know for certain is if this engine is externally balanced. I've been told the crank bolt pattern is indexed. The only reason for that is if the CAS reluctor is on the flywheel or if the engine is externally balanced.

Hey alnielsen, how's the flooding around Chicago? I hear it's pretty bad in some spots. You any relation to Neilson Enterprises?

 

it occurs in the 88-89 929 MANUAL only (auto is 3.9), of which there are 5. and the 89-91 MPV 2wd manual, of which there were twelve. part is NLA new.

so that's perfect.

 

5? Is that a production number? Car-part shows 2 carriers for 929 manuals of that year.

 

sarcastic production number i've seen maybe two stick shift 929's in my life? that makes it a rare car!

if you want perspective, i've seen 13 of 39 Ferrari GTO's all parked in a row together.

 

A manual trans 929? Nice.

 

24" wheels & tires, problem solved ...

 

Disagreeing with you is not belittling you.

I do know what I'm talking about. If you look at my sig, you will see that I have done some amateur racing. That means I have had to modify and wrench on my cars. I have pulled the flywheel of 2 RX7's and this RX8. The oem flywheel has an offset balance. The Mazdaspeed flywheel, and other aftermarket lightweight flywheels, require the addition of a counterbalance made for a automatic trans model to re-balance the rotary engine.
Yes, I've been riding motorcycles since I was 17, that makes it 40 yrs. I've never had a sport bike. The closest thing to it was when I turned one of my Kawasaki triple 2 stroke street bikes half way into a cafe racer. That was 25 yrs ago before it was fashion to do so.
I wish. It would give me easy access to motorcycles and snowmobiles.
My area, in the western suburbs, got hit the hardest by the tstorms. There is a lot of impassable streets due to flooding. Fortunately, for me, I have a second car. I have a lifted Jeep Cherokee. It takes a lot of water before I can't get through. My lowered RX8 is all together a different story.

 

wasn't referring to you... i understand what you posted to me was respectfully written and well reasoned... and i understand 2 people can disagree without malice...

i was referring to this post...

i have read quite a bit of this forum and many many of his posts and unfortunately i have found that practically every one of his i have read creates this photo in my mind...

 

Well, but you quoted me.
While I haven't met him personally (he is 5000 miles away after all), I have had conversations on here with him over the years. He too is a racer and does his own work on his cars. He is a brash young man and should use a little restraint when criticizing. While he has an excellent command of English, it isn't his first language.

 

Hey everyone.

I personally have owned BOTH a RX-8 and a Isuzu VehiCross (with the 3.5L in it). Actually I still own the VehiCross and am still loving it but sold the RX-8 after it took Mazda well over 4 months and 4 different "newly rebuilt" engines to replace my blown one under the 100k extended warranty.

And guess what? 2 years after I sold the RX-8, the 3.5L engine in my Isuzu blew as well. So I have had the 3.5L Iszuz engine removed and totally rebuilt, rebored, everything! And 3 weeks later the head gaskets blew so they had to take it out again.

I know what you guys are thinking, but I absolutely baby my cars to death. Meticulously change oil with Mobil 1 fully synthetic and NEVER run low on oil. BUT BOTH engines are known to be unreliable and burn oil. My RX-8 engine just blew because it was about 80k miles and badly designed, that is why Mazda knew they had to extend the warranty to be forced by outside sources to issue a recall.

My 3.5L Isuzu engine blew because of 2 problems, an oil ring issue that was address and fixed in 2002 and later Isuzu engines AND a faulty Fuel Pressure Regulator that was leaking fuel on top of the #6 cylinder.

My advice, if you are going to replace the RX-8 engine, do not replace it with a 3.5L Isuzu from before 2003. I am speaking from WAY too much experience here ;-)

 

I found a deal on a 2002. The only revision that I know of was some extra drain holes added to the pistons. Don't use **** oil and use synthetic or Rotella it'll be fine. It's just an engine. Ask yourself, who cares for Isuzus anyways? People buy them used and run them into the ground.

As far as I'm concerned (piston) engines are all the same. Metal is metal. It's not 1920 here. The differences come into play when you start asking engines to do more then they were designed for. Like boosting or neglecting them. Supermarine is supercharging the Isuzu in aircraft so that's speaks for it's quality. There's also the off-road guys who beat the hell out of them in the mud. Everything about the Isuzu design is great except for the cast crank and partially open deck. Mazda, on the other hand, blew it and they knew it.

If your blowing head gaskets I'd wonder who your rebuilder is. I'm guessing the deck and/or heads were never resurfaced. The Isuzu engine isn't known for blowing head gaskets even in boosted applications. They're also very detonation resistant. Don't let the name tarnish the engine's design.

 

Your rational on Isuzu engines blows me away. If you look at the forums for them there are a ton of dedicated owners who take meticulous care to keep the engines going and often that's not enough. But it must be the owners beating them up and they how could they be known for burning oil because you havent seen the blue smoke coming from all the Isuzus. Like I've already said your not listening to the input about the engine you've chosen, I agree there are tons of options around transmissions but your still not going to have a worry free car. Hopefully you rebuild the engine with revised pistons and pray nothing else goes.
Decat, sorry to here about your vehicross hope mine continues to hold up like it currently is.

Edit- how much of that Isuzu engine is stock from supermarine. Your plan is to buy a cheap engine not a built, supercharged, engine with standalone programming from supermarine. Also might want to look into how much maintenance gets done on airplane engines and how long before they hour out vs what people use engines for in cars. There's a reason flying costs 100's of dollars per hour for a small plane.

 

You guys might as well as be talking to a brick wall. Don't waste your time here because this swap will never be finished.