Milwaukee Midget

[fordboy628]

midget,

Quote from Diamond for a set of 4 pistons & pins, at cost:

75.5 mm bore dia; 30 mm comp ht.; 16 mm pin dia.

Fully machined billet only, grooved to suit rings supplied.
pins H11 custom only


No ring pack in quote.  You need to supply

   $807.00
+$250.00    for scanning combustion chamber mold
+  shipping, etc.

Probably looking @ $1100 total cost and you will need to either throw them a "bone" or order yourself.    Not sure what price you might get quoted as an individual buying direct.

Good news is:  delivery in 3-1/2 weeks or so plus time in shipment.

 
F/b

[Rex Schimmer]

Chris,
I was searching back in you build post for some info on your pan chop and ran across your thinking about possibly using an Accusump for additional oil volume. If you and F/b decide to go that way let me know I have an approx 2 qt Accusump that you can have for the cost of the freight, I will also provide a 12VDC isolation valve. These are parts from our lakester that I decided we really didn't need and so removed. Just taking up space in the shop.

Rex

[Milwaukee Midget]

Chris,
I was searching back in you build post for some info on your pan chop and ran across your thinking about possibly using an Accusump for additional oil volume. If you and F/b decide to go that way let me know I have an approx 2 qt Accusump that you can have for the cost of the freight, I will also provide a 12VDC isolation valve. These are parts from our lakester that I decided we really didn't need and so removed. Just taking up space in the shop.

Rex

I'll take it, and THANK YOU, Rex!

 

[Jack Gifford]

Sounds like "at cost" is a good deal. Four billet pistons for my hemi were $1,600 from Diamond.

[fordboy628]

Sounds like "at cost" is a good deal. Four billet pistons for my hemi were $1,600 from Diamond.

YIKES! ! ! !

This racing crap is just getting too darn expensive . . . . . .

Certainly it has been that way all along, but now, even I am staggered by the dollar amounts.



Fly fishing & fly tying is WAAAAYY more affordable.

 
Flyfishingboy

[fordboy628]

midget,

In order to get the oil pan welded up, I am going to need you to send down or bring down ALL the fasteners for the oil pan, the lower sump/girdle, and the balance of the old head bolts.  The need is not immediate, so just fit it into your schedule so that they arrive next week.

 
Weldyboy

[fordboy628]

midget,

Quote from Diamond for a set of 4 pistons & pins, at cost:

75.5 mm bore dia; 30 mm comp ht.; 16 mm pin dia.

Fully machined billet only, grooved to suit rings supplied.
pins H11 custom only


No ring pack in quote.  You need to supply

   $807.00
+$250.00    for scanning combustion chamber mold
+  shipping, etc.

Probably looking @ $1100 total cost and you will need to either throw them a "bone" or order yourself.    Not sure what price you might get quoted as an individual buying direct.

Good news is:  delivery in 3-1/2 weeks or so plus time in shipment.

 
F/b

midget,

I'm not sure whether this quote specified any coatings or max lightening or anything else.

I'll work on getting that information today.

 
F/b

[Milwaukee Midget]

Unlike last time, I want to leave a little extra meat on the piston tops, just in case we need to do something unforseen. The

[desotoman]

midget,

Quote from Diamond for a set of 4 pistons & pins, at cost:

75.5 mm bore dia; 30 mm comp ht.; 16 mm pin dia.

Fully machined billet only, grooved to suit rings supplied.
pins H11 custom only


No ring pack in quote.  You need to supply

   $807.00
+$250.00    for scanning combustion chamber mold
+  shipping, etc.

Probably looking @ $1100 total cost and you will need to either throw them a "bone" or order yourself.    Not sure what price you might get quoted as an individual buying direct.

Good news is:  delivery in 3-1/2 weeks or so plus time in shipment.

 
F/b

Maybe this is a silly question, but why do you need Billet pistons?

Can't you find a motorcycle forging, or other forging that would work in your bore size?

Tom G.

[Milwaukee Midget]

Maybe this is a silly question, but why do you need Billet pistons?

Can't you find a motorcycle forging, or other forging that would work in your bore size?

Tom G.

We're looking for the sweet spot with respect to overall piston height and rod length.  Most MC pistons are fairly short.  We'll likely want a crown height of between 30 and 32mm, with a pin substantial enough to handle 10,000 k.

The issue is the deck height.  We need to go with a taller piston overall in order to construct a rod that doesn't give us a R/S ratio that is ridiculously high.

[jacksoni]

 Pin height vs Rod ratio- argued about more than TQvsHP, which is more important. Trade offs of all sorts. My rod ratio is 2.42. Izzat "ridiculously high" ? Makes 145+hp/liter. Makes cam design interesting.  And my pistons from JE were in that range first go around and they were starting from a design they already had. 

[Milwaukee Midget]

Well, if we can go with a 30mm crown height, then we're talking a 2.59 R/S ratio. 

I'd rather see it at 2.42, but if my calculations are correct, then we're talking almost a 40mm crown height.

Again - trying to find a "sweet spot" . . .

[jacksoni]

Chris, my comments here are not to try to push in any direction but just to add to the mix a bit and with personal experience. Mark has I am sure pitched in already and surely go with his ideas. Of course the whole issue is taking an engine that works  and change something significantly for your purposes. Destroke from whatever it was to 1 L. It will rev high and piston speeds will be OK even with  high revs but there are cam, intake, exhaust etc issues that make design of those parts problematic to work best with the new configuration. Among the things that change a lot will be the "rod ratio". Many people say there is an "ideal' ratio that is in the 1.6-1.7 range. (maybe up to 1.9). Interesting as F1 goes up to 2.4 or so in order to have the really low deck so fits under the body work. Whole different animal.  Anyway, I only destroked from 2.5L to 2L and decreased bore at same time to help. I spent lot of time reading and talking to some very respected engine builders (Pro stock, Nascar) etc. The guy who built my cylinder head, and it was a good one, said: "Pick your stroke, pick best piston you can get for weight- impacted by pin height etc_ and the rod connects the two. Don't worry about Rod Ratio". I ended with  2.58 stroke and 6.25 rod with  1.48 (about 37mm) pin height. He said is that all you can do?- Wanted shorter pin height. Reason being the piston weighs less and is less likely to rock in the bore with the pin moved up.  There is some trade off in rod weight but on balance most I have seen suggest lighter piston is better compromise. This guy said on dyno you can't see the rod ratio and we have tested many many combinations. ( Reher Morrison Race engines). On the track there may be some difference in some circumstances which is why some engine builders do want more "ideal" rod ratios. Bonneville I do not think falls into this category. If you look there are all kinds of things that people will say with such and such situation (port limited engine for instance) you want a longer rod and other situations you want a shorter rod etc. Problem is you can realistically make only small differences once you have crank and block specs set. If you want to see such charts , I will look them up and post. But in your case, you are stuck. You can't deck the block a lot and you trade off piston weight and rock for rod weight and ratio (which may make little difference.) A good cam designer will want to know everything ( have we heard " what matters?"= EVERYTHING on this thread) including rod ratio to best design your cams. Including what you are doing with the engine. = WFO for 2 minutes with just go through gears getting there one time. 30mm pin height doesn't leave lot of space for ring package, though is certainly done,  and that is an important consideration. If that works and it does give a lighter piston etc etc, I wouldn't worry about the rod ratio. that's just me though and I readily admit to not being a pro here. Point is, don't think there is really a sweet spot in this setting, just which sort of compromise seems to work best with part availability and cost.

I continue to follow with great interest. 

[desotoman]

We're looking for the sweet spot with respect to overall piston height and rod length.  Most MC pistons are fairly short.  We'll likely want a crown height of between 30 and 32mm, with a pin substantial enough to handle 10,000 k.

The issue is the deck height.  We need to go with a taller piston overall in order to construct a rod that doesn't give us a R/S ratio that is ridiculously high.

Thanks for the reply.

Tom G.

[Milwaukee Midget]

Hi, Jack -

Your input is always welcome, and if my comment seemed to give short shrift to your input, then I've failed in my tone.

In our case, the "sweet spot" will probably wind up being anything that might actually work.

And yes, the arguments go back and forth on the R/S "debate".  At the end of the day, my choice in conjunction with rulebook-imposed class limitations, puts me into territory few builders - and fewer hobbyists - ever wind up exploring.

You and your builder friend are probably right about the R/S - we simply have to build around it, or, if possible, use it to our advantage.

The big bugaboo I see on the immediate horizon is the relatively long time the piston spends toward the top of the stroke at overlap with respect to the timing events.  This is partially the result of the big R/S ratio, but is also a result of our desire for a high compression ratio and a small engine capacity. 

This time around, of course, we have the advantage of being able to adjust cams independently, so that gives us wiggle room for physical operations within the combustion chamber. 

I was able to accidently introduce a valve to the piston on the A-series and we lived to tell the tale, but that was a vertical valve head.

A pent-roof, four-valve would likely be less forgiving.