engine lightening

[squidrope]

12 wrist pins completed. I estimated a 10 gram loss per pin. I am happy to say I was wrong. Wrist pins lost 15 grams each. They went from 105 to 90. :)

[squidrope]

Almost wish I'd bought aftermarket rods. After all of the machining, balancing and polishing I just dropped $340 to have the 12 rods shot peened and magna-fluxed. The good news is that I have a fair amount of experience working rods... Bad news is that I'm getting frustrated by the pace and amount of work involved. Wrist pins are being finish EDM'ed and the lower edge of the piston skirts have been radiused for better oiling.

[squidrope]

Although I made fixtures to help with the rod balancing process we struggled to get consistent numbers especially when weighing the large end of the rods. After much head scratching and process modifications we were able to get some consistent results of the smaller ends. All of the smaller ends varied less than a gram from one another, which was probably due to that end being mostly machined. Rod caps were placed in the CNC, programs written, and material machined off to balance the rod weights. Woo Hoo the connecting rods are 95% done! Total weight removed is about 85grams per rod. Now I'll have them stress relieved (bead blasted) and they'll be ready for assembly.
The wrist pin EDM fixture is in need of modifications as the grit from the process is making it impossible to fit subsequent pins in the fixture. that should yield another 10ish grams of weight loss.

[squidrope]

Been busy polishing the rods. It takes me a little more than an hour per rod. Ugh. Polishing removes another 7 grams per (82grams/rod so far). I've also built the 2 rod balancing fixtures and will try and get the rods balanced this weekend.

[squidrope]

Big block is now a narrow rib. Weight loss in the transformation is about 27 grams. Upon closer examination of the big block on the cap, I believe it's main purpose was to balance/equalize the weight of the rods.
I've been machining 16 rods (6 race, 6 spare motor, 4 spares for balancing) during this adventure. All 16 of the rods weigh within 9 grams, 14 are within 6 grams of each other. I haven't started to equalize the end weights as I will be polishing the forge finish and have some hand work to blend the machined areas. I'm not sure how much material will be removed by that process, but I've trimmed about 75 grams per rod so far. After the equalizing, polishing, and blending I estimate that another 10-15 grams will be removed. That's a 85-90 gram loss on a 600ish gram rod (w/bolts).
Very happy with how everything looks so far, and can't wait to be done with the rods.

[squidrope]

Best focus on rotating part of rods the reciprocating mass has little effect on how fast the engine revs up or responds.

Didn't know that. Thanks. The big block on the cap is going on it's diet tomorrow.

[digger]

Best focus on rotating part of rods the reciprocating mass has little effect on how fast the engine revs up or responds.

[squidrope]

7 more grams from the wrist pin area. Rethought original narrowing of the wrist pin area. Tapered O.D. for upper 180 degrees.

[squidrope]

I've put a full radius along the edges that run parallel to the rod bolts and the rods lost an additional 20 grams. That's 40 grams so far and I haven't touched the large block on the cap end, or tapered the wrist pin end.

[squidrope]

Interested in the particulars on these.

BMW motorcycle alt. (constructing the mounting bracket was a huge PITA).
Machined off harmonic pulley and built smaller diameter "pulley" that I then attached to the harmonic dampener.


I'll put some pics up on our facebook page "Squidrope Racing"

Pics are up minus the altenator stuff, that stuff's hiding in a box somewhere...

There are pics of the beginning of the rod lightening and pics of the lightened flywheel as well.

[vpilarrt]

swapped to a motorcycle altenator, reduced water pump rpm

Interested in the particulars on these.

[squidrope]

What are you trying to achieve by lightening parts ? I would focus on the low hanging fruit e.g lightweight flywheel if you want it to rev quicker

I've already lightened the flywheel, swapped to a motorcycle altenator, reduced water pump rpm, and removed weight from fixed portion of harmonic dampener.


This car is a track car (24 Hours of Lemons) and I'm looking to improve throttle response.


I'm replacing the valve guides with longer guides. The intake and exhaust ports will be machined to remove the "bump" by the guides, and the longer guides will also be machined flush to improve flow. Intake manifold will be pinned and matched to the head and o-ringed instead of gasket. etc etc etc

[digger]

What are you trying to achieve by lightening parts ? I would focus on the low hanging fruit e.g lightweight flywheel if you want it to rev quicker

[squidrope]

Glad I found this thread as I'm undertaking a similar build. Any info on how the final build ran?

Profiling the CR (I-beam and piston end) has netted 20 grams. Planning on taking more weight off the crank end (haven't decided where or how much) and will taper piston end so the wrist pin hole is thinner on the top same thickness on the bottom.

Tapering wrist pin holes in piston area on both ends.

Thinking of windowing pistons to improve oiling and decrease weight.

Will be knifing crank leading edge and want to lighten counterweights but unsure if lightening will make crank unable to be balanced?

[homegrone30]

i would welcome any actual answers as to the purpose of the giant freekin block at the base of the rod caps.

I always were told those were for balancing from the factory.