Have you checked end weights on the rods to determine which end to shave? That would be my next step.

It easy to see your outlier on the pistons.

Jamie, I see your point, but the rods are coated with oil shedding coating, so I am hesitant to start grinding. I'd prefer to work on the pistons. Not to mention, the R&R rods are pretty brutally perfect...you should see them. The put Carillos to shame.

Here are the weight-matched assemblies (g):

Pistons Rods Pins Total
419.9 538.1 108.9 1066.9
419.9 538.6 109.0 1067.5
419.9 539.1 109.0 1068.0
419.6 539.1 109.1 1067.8
419.4 539.1 109.1 1067.6
418.5 539.2 109.1 1066.8


1.2g delta is the max (heaviest to lightest) when the assemblies are matched for weight, but even smaller when you compare the deltas for weight matched assemblies on opposite sides of the crank:

bank1 bank2 bank3
0.2g 0.1g 0.1g

Is it even worth trying to get all parts to zero delta? Seriously, .2g net...

Mmmmmmm...titanium wrist pins:

Diameter__Length___Wall____Weight
.866"_____2.500"___.206"___76g

76g for the pins shaves ~33g from each end of the rotating assembly. Only $100/ea :eek:

http://pppcenter.com/pinprices.html

Well, yea, that IS a good question. Big picture, I'd have to think some assemblies will have more oil on them than others at any particular point, and that difference alone would, I think, be more than .2G.

Kenik,

I think the overall balance is great. 0.2g will not be noticeable and it is certainly a tighter tolerance than factory spec.

I was referring to the end weights of the rods. I don't expect any differences but you have gone this far you might as well check.

The one piston that was a gram lighter then the others caught my attention. I did not realize you had a rod that weighed enough to compensate. I would think that the difference in piston mass would be more highly "weighted" than the difference in rod mass. Remember, the piston/pin assembly is always in full 1D motion. The rod weight will be partially offset by the crank angle since it is attached to both the crank and the piston. Will it make any difference based upon the sum numbers you have posted? Probably not. would I personally spend a few moments considering the impact. Yes. Would I then act upon this thought. likely not.

I guess it just comes down to not liking the one single light rod and one single light piston. I know the rpm level you are going to run the motor. IMHO, Anything you can do to increase balance at that engine speed will pay dividends in longevity.

So you changed your mind again?

No, all is the same as the last time we talked. Some things just haven't been updated. I'll share more as things progress. Right now, it is all about the short block assembly. :D

subscribed.

Just for sport, I am curious if someone out there has the piston velocity numbers say at Keniks peak rpm and what the resulting forces would be once you plug in the weight differential across the pistons.

Fun build!

@7800 RPM

Piston Speed 3377.953 FPM
Piston Speed 56.299 FPS

I will need to find teh formula for force at crank angle...

Unverified google'd list I lifted off of a VW forum which makes for some interesting reading/comparisons. The thought of making 40+ year old technology spin up to 8k is very intoxicating. Go Kenik Go!

1. Honda S2000:
Engine Code: F20C1
Bore/Stroke: 3.43" X 3.31"
Redline: 9000rpm
Piston Speed: 4965 Ft/min
2. Lamborghini Gallardo
Engine Code: N/A
Bore/Stroke: 3.25" X 3.65"
Redline: 8000rpm
Piston Speed: 4866.67 Ft/min

3. Acura Integra Type R
Engine Code: B18C5
Bore/Stroke: 3.19" X 3.43"
Redline: 8400rpm
Piston Speed: 4802 Ft/min

4. BMW M3 (Germany)
Engine Code: S54
Bore/Stroke: 3.43" X 3.58"
Redline: 8000rpm
Piston Speed: 4773.33 Ft/min

5. Honda S2000 2004
Engine Code: F22C
Bore/Stroke: 3.43" X 3.57"
Redline: 8000rpm
Piston Speed: 4760 Ft/min

6. Honda Integra Type R (JDM)
Engine Code: K20A
Bore/Stroke: 3.39" X 3.39"
Redline: 8400rpm
Piston Speed: 4746 Ft/min

7. Acura Integra GSR 2001
Engine Code: B18C
Bore/Stroke: 3.19" X 3.43"
Redline: 8200rpm
Piston Speed: 4687.67 Ft/min

8. Saleen S7
Engine Code: N/A
Bore/Stroke: 4.13" X 4.00"
Redline: 7000rpm
Piston Speed: 4666.67 Ft/min

9. Acura TSX
Engine Code: K24A2
Bore/Stroke: 3.43" X 3.90"
Redline: 7100rpm
Piston Speed: 4615 Ft/min

10. Suzuki Hayabusa Sport Prototype
Engine Code: W701
Bore/Stroke: 3.19" X 2.48"
Redline: 11000rpm
Piston Speed: 4546.67 Ft/min

11. Honda Civic Type R
Engine Code: B16B
Bore/Stroke: 3.19" X 3.03"
Redline: 9000rpm
Piston Speed: 4545 Ft/min

12. Toyota Celica GTS / Matrix XRS 2001
Engine Code: 2ZZ-GE
Bore/Stroke: 3.23" X 3.35"
Redline: 8100rpm
Piston Speed: 4522.5 Ft/min

13. Honda Prelude Type S (JDM)
Engine Code: H22A
Bore/Stroke: 3.43" X 3.57"
Redline: 7500rpm
Piston Speed: 4462.5 Ft/min

14. Acura RSX Type S
Engine Code: K20A2
Bore/Stroke: 3.38" X 3.38"
Redline: 7900rpm
Piston Speed: 4450.33 Ft/min

15. Ferrari 360 Modena (incl. Challenge, Stradale, etc)
Engine Code: N/A
Bore/Stroke: 3.35" X 3.11"
Redline: 8500rpm
Piston Speed: 4405.83 Ft/min

16. Lamborghini Murcielago
Engine Code: N/A
Bore/Stroke: 3.43" X 3.42"
Redline: 7600rpm
Piston Speed: 4332 Ft/min

17. McLaren F1
Engine Code: N/A (BMW V12)
Bore/Stroke: 3.39" X 3.43"
Redline: 7500rpm
Piston Speed: 4287.5 Ft/min

18. Renault Clio 2.0 RS 2003
Engine Code: F4R
Bore/Stroke: 3.26" X 3.66"
Redline: 7000rpm
Piston Speed: 4270 Ft/min

19. Porsche 911 GT3 RS 2004
Engine Code: N/A
Bore/Stroke: 3.94" X 3.01"
Redline: 8500rpm
Piston Speed: 4264.17 Ft/min

20. Pagani Zonda C12S
Engine Code: M120 7.3 AMG
Bore/Stroke: 3.6" X 3.64"
Redline: 7000rpm
Piston Speed: 4246.67 Ft/min

21. Peugeot 206RC 2004
Engine Code: EW10 J4 S
Bore/Stroke: 3.35" X 3.46"
Redline: 7300rpm
Piston Speed: 4209.67 Ft/min

22. Porsche Carrera GT
Engine Code: N/A
Bore/Stroke: 3.86" X 2.99"
Redline: 8400rpm
Piston Speed: 4186 Ft/min

23. Acura NSX-T
Engine Code: C32B
Bore/Stroke: 3.66" X 3.07"
Redline: 8000rpm
Piston Speed: 4093.33 Ft/min

24. BMW M5 2002
Engine Code: S62
Bore/Stroke: 3.70" X 3.50"
Redline: 7000rpm
Piston Speed: 4083.33 Ft/min

25. BMW M5 E60
Engine Code: S65 (?)
Bore/Stroke: 3.62" X 2.96"
Redline: 8250rpm
Piston Speed: 4070 Ft/min

26. Nissan Primera W20V
Engine Code: N/A
Bore/Stroke: 3.39" X 3.39"
Redline: 7200rpm
Piston Speed: 4068 Ft/min

27. Ferrari Enzo
Engine Code: F140
Bore/Stroke: 3.62" X 2.96"
Redline: 8000rpm
Piston Speed: 3946.67 Ft/min

28. Ferrari 575 Maranello
Engine Code: 650 V21
Bore/Stroke: 3.50" X 3.03"
Redline: 7750rpm
Piston Speed: 3913.75 Ft/min

For reference: 66mm = 2.5984"; 85mm (my bore) = 3.3465"
The only engine that compares is the Hayabusa!

You have to love the sane piston speeds a 66mm stroke brings. :) That said, the old school JE pistons are not nearly as light as X-member skirtless flat top pistons, like in more modern cars. This is where the piston forces come into play. Also, since the 911 is 2 valve, you have interesting dynamics to deal with in terms of valve train momentum that doesn't exist in 4 valve heads. Only the Vette motor (assuming this is what the C7 uses) has 2 valve heads from what I can see above and those new Vette's use titanium valvegear and lower engine speeds (assisted by huge displacement) to manage valve float.

I would love to get some scaled down GT3 heads! :eek:

66x127x7800
 

Hope my calcs are right....

66 stroke + 127 rod + 7,800 rpm = 27,738 m/s^2 peak acceleration (about 2,800 G's)

Careful tightening those conrod nuts....

http://forums.pelicanparts.com/uploa...1257382893.jpg

You missed one thing - the rods are GT3 spec, 130mm.

130mm ---> 27,606 m/s^2 (not a great difference, but every bit helps)

Thanks for the numbers jcge!

http://forums.pelicanparts.com/uploa...1193167485.jpg

I don't think it's worth it, for an F1 engine, yes.

Damn, John! NICE spreadsheet. You are even using the Porsche font!

Man this is a good "how to" video on balancing rods:

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Kenik, all you have to do is build your conrod weight or massing jig and buy a belt sander :D

Great vid.

Well, I am a bit of a multistasker, so I am setting down the motor bits until I can get access to my buddy's cc'ing fixture.

As you will recall from the first page of this thread, I did some pretty serious surgery to the rear fenders. The process of attaching a set of nice '69 fenders has been dependent upon my getting around to fitting tires to my wheels, for fine tuning of the fender placement. Well, I finally got around to it. :)

This was the best deal out there, given my tire size preferences, meaning narrow body and vintage high sidewall (meaning NO 205/55/15 and 225/50/15 combos):

Bridgestone Potenza RE960AS Pole Position
Currently Available Prices and Sizes
They are damned near the equal of the Michelin Pilot Sport (which can't be had in our fitments anymore).

$315 for a set of 4 and great traction/reviews:

http://forums.pelicanparts.com/uploa...1250363265.jpg

I kept thinking I would buy the Avon CR6ZZ tires, but FOUR of these tires cost as much as ONE of the CR6ZZs...decision made.

Their speed rating isn't great, but I won't ever see any road speeds above what these tires are rated, so it is an academic point.

Anyhow, below are my newly mounted wheels and tires: all are widened deep sixes with the 7R offset. The fronts are 7" wide (7R spec) and the rears are 7.75" wide (what I call 8R spec ;)). These will fit under the narrow body fine and I could have gone 7R all the way around, but really wanted to dial in the sidewall "bulge" to be identical, front to rear. All wheel work, of course, done by Harvey Weidman.

http://forums.pelicanparts.com/uploa...1257798569.jpg
http://forums.pelicanparts.com/uploa...1257798584.jpg
http://forums.pelicanparts.com/uploa...1257798599.jpg
http://forums.pelicanparts.com/uploa...1257798611.jpg
http://forums.pelicanparts.com/uploa...1257798623.jpg

Next, I will need to procure some 100mm studs and install on all 4 corners so I can fit the wheels. I will start fitting the rears by stacking 7mm spacers for test fit, then shim up the studs with washers until I get the wheels to just clear the fenderwell hardware. Then if the critical dimension is under 21mm, I'll take my turbo spacers to be turned down to the final dimension of the spacers/washers. If larger than 21mm (I am pretty sure it isn't), then I will need to source some larger spacers or check the viability of stacking spacers (initial gut check = not a good idea). Finally, I'll mark my studs, remove them, then turn them down to a nice flush fit for the lug nuts.

From there I can section the rear fenders to fit my panels and trim the panels to fit. With the help of a few welding clamps, I should have the fenders ready for test fit, then it is just a few tack welds and time to get TIGing.

Some will comment that this combo leaves me a bit undertired, but I just don't care. So THERE! :p If it is half as fun as the 165 tired, 2.7 twin plugged hot rod that was in one of the British 911 mags this month, I'll take it.

I will of course share pics when available.