Lightened rods

[jdoclogan]

As I move forward on some Alpine engine builds it occurred to me I should go through all of the Max Phameier parts I acquired. Particularly the engine parts from the 1960's Stetina race car. What I found was a set of lightened and polished rods. The photos below show the lightened rod (L) and the stock rod (R).







The weight comparison:

Lightened 553 grams with bolts (83 grams) = 636 grams
Stock 661 grams with bolts (86 grams) = 747 grams

 

[Aladin Sane]

Wow, that looks like a lot of beef was removed.

 

[husky drvr]

Wow, that looks like a lot of beef was removed.

With the listed weights, it's right at a pound (0.9504 lbs.) of rotating and reciprocating weight.

 

[alpine_64]

Jerry great period parts... The rod mods are extensive.. And under scca in period they had to use stock rods iirc.. So work them as hard as they can..
Tbe irony now are the stronger lighter substitutes we can buy and substitute.. But nevertheless. Great period performance sunbeam.history there

 

[jdoclogan]

And I find another set of lightened components from the 1960s Stetina race car. Modified rocker arms that move with significantly less friction (bottom set) than the stock rockers (top set).
Note: the solid spacer between arms in modified vs spring in stock.

Stock assembly = 2100 grams
Mod assembly = 1870 grams

 

[jdoclogan]

The connecting rods at the top of thread are from a 1725 engine. I found a set of lightened 1592 rods with the same treatment.
Comparing the 5.7 inch lightened 1592 to stock 1592:

Lightened/with bolts = 576 grams
Stock/ with bolts = 692 grams
Again 1lb of rotating weight eliminated.

Now compare some modern marketed rod substitutes.

Eagle 5.7 inch H beam rods = 570 grams $103 per rod (One Lot of 6)
https://www.summitracing.com/parts/esp-5700slw-6/make/chevrolet#overview

Speedway Motors H beam = 622 grams. $44 per rod (one lot of 8)
https://www.speedwaymotors.com/Smal...am-Rods-Bushed-Pin,1790.html?sku=91015328-5.7

I will point out any of these rod sets are able to handle engines with 500+ horsepower. That's 62+ horsepower per rod for a V8. Our entire engine can only do around 125 horsepower maximum (31 horsepower per rod). I believe any one of the above rods would do just fine for the Alpine 4 cylinder engine.

 

[Alpine 1789]

I wonder what the Chevy rods weigh? I never thought to weigh mine and don't recall ever seeing it in any of the discussions on them. Jan Servaites included extensive measurement comparisons between them and stock rods in an old Marque article, but I don't see any mention of the weight difference. https://sunbeamalpine.org/wp-content/uploads/2017/10/issue_14.pdf. I remember being told that the Chevy rod conversion reduced the rotating mass by 4 lbs, but I don't know how accurate that is and it would include the metal removed from the crankshaft.

 

[Bill Blue]

I wonder what the Chevy rods weigh? I never thought to weigh mine and don't recall ever seeing it in any of the discussions on them. Jan Servaites included extensive measurement comparisons between them and stock rods in an old Marque article, but I don't see any mention of the weight difference. https://sunbeamalpine.org/wp-content/uploads/2017/10/issue_14.pdf. I remember being told that the Chevy rod conversion reduced the rotating mass by 4 lbs, but I don't know how accurate that is and it would include the metal removed from the crankshaft.

In addition, I think that Jim Ellis said the 4 pound reduction included the use of modern pistons and possibly different piston pins. In other words, total reciprocating
weight comparison.
Bill

 

[Alpine 1789]

That would make sense. Note to next owner building a Chevy rod engine: please weigh the rods and the crank before and after.

 

[spmdr]

Oh the fun of Decades gone by!

And OH, would the balance shop have fun Balancing those rods that are already trimmed to the Bone!

I'm wondering what, and better yet HOW, to trim the counter weights on the Crank to match the lighter parts?

...And I mean how to determine how MUCH to take OFF.

 

[jdoclogan]

That would make sense. Note to next owner building a Chevy rod engine: please weigh the rods and the crank before and after.

Jim,
Apparently Bernd did just that (weighed stock Chevy rod) based on a comment Bernd made a few months ago:

"Here is an excerpt of my initial studies which I shared in UK Forum earlier:

Chevy rods on 1592cc: Actually they would fit even better (compared to 1725cc )since they also have the 2" big end diameter. Same as for the 1725 the crank must be slightly ground at the big end sides (+ 1mm would make them suit perfectly). Small end needs to be slightly bored to accept piston pin (same as for 1725).Ultimately the Chevy rods are substantially lighter than the originals

After all this confirms my theory that a real 1592cc screamer could be built out of the components mentioned

.

P.S. The weight saving per rod is around 180g ; total therefore = 720g -> Very substantial for a smaller displacement engine..."

If I incorporate some simple math it appears the Chevy rod is:
Stock 1592 rod = 692 grams - 180 grams = Chevy rod = 512 grams
That comes to 1.5 lbs of total rotating weight loss for the Chevy rod replacement.

EDIT:
I'm not certain how accurate this is because I'm only finding one modern rod in that low 500 gram area that is very expensive ($230/rod). But, I haven't got access to an original straight six Chevy rod to confirm.

 

[jdoclogan]

Oh the fun of Decades gone by!

And OH, would the balance shop have fun Balancing those rods that are already trimmed to the Bone!

I'm wondering what, and better yet HOW, to trim the counter weights on the Crank to match the lighter parts?

...And I mean how to determine how MUCH to take OFF.

Dan,
I believe I have found an engine build shop that has the best reputation around my area for building excellent race engines. I've spoken on the phone to the owner. Now I need to go see the operation and have a face to face conversation with the owner.

 

[jdoclogan]

I wonder what the Chevy rods weigh? I never thought to weigh mine and don't recall ever seeing it in any of the discussions on them. Jan Servaites included extensive measurement comparisons between them and stock rods in an old Marque article, but I don't see any mention of the weight difference. https://sunbeamalpine.org/wp-content/uploads/2017/10/issue_14.pdf. I remember being told that the Chevy rod conversion reduced the rotating mass by 4 lbs, but I don't know how accurate that is and it would include the metal removed from the crankshaft.

I just found a H beam rod that is claiming 16.1 oz = 456 grams weight for $230/rod. That would get you the 4lbs of rotating weight savings just from the rods. https://www.alpermotorsports.com/index.php?l=product_detail&p=1160

 

[spmdr]

Just to all get on the same page...

A lot of rod weight savings comes from the Big end.

In the balance world, Rod big ends are basically known as Rotating weight.

Rotating weight is not as critical as Reciprocating weight.

And it's usually WAY easier to remove rotating weight from a Flywheel than rods.

Of course, removing as much unnecessary weight from EVERYTHING is a big goal in general.


One of the Tiger engines I built had early unique custom rods with extra wide big ends.

It has FAR and away more balance bob weight than any other engine I have built ( BUT with quite low reciprocating weight)!

Yet it still revs as quick as any other engine I have built.

...but of course, it also has just about NO flywheel!

SO, the bottom line: Reciprocating weight, Let's compare THAT.

 

[jdoclogan]

It appears as though I have found a good match. While processing all of the options I never got away from the thought that Jan Servaites stated "The straight six Chevy Rod is the way to go." Here is what I found and it is very economical:

A set of 8 Chevy rods $299/free shipping (that is $38/rod). This matches the original Sunbeam rod dimensions with improved quality.

Edited 12/18/2021: this is the bush type rod.
Brand:
Eagle Specialty Products
Manufacturer's Part Number:
SIR5700BBLW
Part Type:
Connecting Rods
Product Line:
Eagle SIR I-Beam Connecting Rods
Summit Racing Part Number:
ESP-5700BBLW
UPC:
793348068602
Quantity:
Sold as a set of 8.
Connecting Rod Length Center to Center (in.):
5.700 in.
Connecting Rod Beam Style:
I-beam
Connecting Rod Material:
Forged 5140 steel
Connecting Rod Finish:
Shot-peened
Wrist Pin Style:
Floating
Rod Journal Diameter (in.):
2.100 in.
Big End Bore Diameter (in.):
2.2250 in.
Pin End Bore Diameter:
0.927 in.
Big End Width (in.):
0.940 in.
Clearanced for Stroker:
No
Cap Retention Style:
Cap screw
Connecting Rod Bolt Brand:
ARP
Connecting Rod Bolt Diameter:
3/8 in.
Connecting Rod Bolt Material:
8740 chromoly steel
Fastener Tensile Strength (psi):
160,000 psi
Connecting Rod Bolt Head Style:
12-point
Approximate Connecting Rod Weight (g):
535
Advertised Horsepower Rating:
500 hp
Advertised RPM Rating:
6,000 rpm
Weight Matched Set:
Yes
Remanufactured:
No
Magnafluxed:
Yes
https://www.summitracing.com/parts/esp-5700bblw

Yes, Jim, hard to beat the cost vs weight savings with this purchase. Set of 8 original matching Chevy rods for $299/2 = $150 per set of 4 rods. I have three engines to rebuild and may still use the original lightened 1960s Stetina rods. Dan, I'll know better what they can provide in terms of balancing if I use the Stetina lightened rods. Actually the savings of 14 grams the Stetina rods give over the Summit Racing Eagle rods is negligible. Maybe the Stetina rods just become a display. As I mentioned earlier all modern rods no matter the cost support 62 Horse Power per rod. We are only doing about half that with a Sunbeam engine.

 

[husky drvr]

It appears as though I have found a good match. While processing all of the options I never got away from the thought that Jan Servaites stated "The straight six Chevy Rod is the way to go." Here is what I found and it is very economical:

A set of 8 Chevy rods $299/free shipping (that is $38/rod). This matches the original Sunbeam rod dimensions with improved quality.

Rod Journal Diameter (in.):
2.000 in.
Big End Bore Diameter (in.):
2.1250 in.
Big End Width (in.):
0.940 in.

Yes, Jim, hard to beat the cost vs weight savings with this purchase. Set of 8 original matching Chevy rods for $299/2 = $150 per set of 4 rods. I have three engines to rebuild and may still use the original lightened 1960s Stetina rods. Dan, I'll know better what they can provide in terms of balancing if I use the Stetina lightened rods. Actually the savings of 14 grams the Stetina rods give over the Summit Racing Eagle rods is negligible. Maybe the Stetina rods just become a display. As I mentioned earlier all modern rods no matter the cost support 62 Horse Power per rod. We are only doing about half that with a Sunbeam engine.

Jerry,

These rods you're showing are for a small block Chevy V8 and are not the same as a six cylinder rod. The big end WIDTH is narrower than the six cylinder rods, and smaller than the O/E rods as well.

From Jan's article:


Another point to make is the Chevy rod’s big end
width (1.030" vs. 1.000" for the 1725) is also larger that the stock rods.
This is really great because the unusable 1725 crankshafts, that have
sloppy ground crankpins, can be reground to have the correct side
play again. An additional benefit is to grind a larger radius in the crankpin
fillets. This will help reduce fatigue cracking. To find these Chevy rods,
you could ask for the Chevy inline-6, 250cu-in, from a 1968 Camaro, or
the Chevy inline-4cyl/140 Mercruiser boat engine. The larger & later Chevy
292 engine should be avoided because the 292 rods are too long (rod
length = 6.750"). The Chevy small block V8 should also be avoided
because the rod’s “I” beam is offset to one side of the rod

 

[jdoclogan]

Don,
I began my reflective processing and was not finding something aligning. You did me a solid by redirecting me to Jan's article quote. Whew, I will continue the search..

 

[husky drvr]

Jerry,

Thank you, glad to be able to help.

 

[bernd_st]

Jerry, all,

some pictures which I took earlier (1st is STD , 2nd is Chevy rod - both with bearing shells):

 

[bernd_st]

Some more (3 mains 1592 crank) :