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New pistons for vintage racing 100M?

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wangdango

wangdango

Jedi Hopeful
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Hello-
after many years our VSCCA racing 100M is in the need for a re bore and new pistons. We have used JE for many, happy years. Our machinist has used both JE and Venolia pistons and really likes the later better. This engine will have a steel crank, (moldex), and Carillo rods, a worked head (steel, w/big valves,etc). We do not want to use DW pistons but rather JE OR Venolia. Any input from the peanut gallery? The last re bore was done way back in 1990 or so and has held up great but it is finally time to rebore, looks like we will be looking at about a re bore of 40 thousands..... ANy help would be great-
Thanks
Ed
 
Wherever you source them, I recommend that the skirts be coated with a dry-film lubricant, and the crowns coated with a thermal barrier.

Even the undersides can benefit from polymer coating; an oil shedding film will prevent the oil from clinging, keeping it cooler and with less parasitic drag (likewise, the external surface of the connecting rods).

IMG_5973.sized.jpg


Combustion chamber, valves, ports, bearings, etc., etc., can all benefit from thermal barrier, thermal dispersant and dry-film lubricant coatings. In the past nineteen (19) years, I haven't built an engine without them.
 
Ed, With names like, JE, Venolia, Moldex, Carrillo These are the best of the best ! You are in good hands. Like Randy says, maybe a dri-film on the skirts and for sure a ceramic coating on the piston tops to reflect the heat back up to the combution chambers where it belongs. I would use coated Rod, Main and Cam bearings also. Good luck, Quick
 
Hello Ed -

If you're looking to just replace with standard flat top race pistons stick with the JE. If you want something more custom, domed for higher compression and matched to your head then I suggest Arias Pistons.

https://www.ariaspistons.com/custompistons.html

Good luck this season,

Dougie
 
Thanks everyone, I think we will stick with flat top pistons and not domed ones. Our machinist thinks a compression ratio higher then 11 to 1 is just asking for trouble. I think we are going to longitivity vs huge HP. Typically we would be running 3 or 4 events per season and hope with all the correct "bits" we can have an engine that will last 3 or 4 seasons. On top of all the engine work we are looking at having a new set of wheels also made up. In the past we had been running 60 spoked painted, heavy duty spoked Daytons, after a few seasons, these are now shot. Next move is 73 spoked heavy duty painted. As we run with the VSCCA, Mini lites are not an option, and they also dont look right on a 100M. Any other input/opinions on piston choices?
Thanks again,
Ed
 
Ed, Check with Denis Welch. They have Cosworth and Omega forged flat top pistons. They are both very good. You might have your machinist check on Mahle pistons also. Good luck, Quick
 
wangdango said:
Randy any idea on the costs associated with doing the coatings?
Click to expand...
It's not cheap, as it's a very demanding and labor intensive process, but if you're looking specifically for reliability and longevity, I'm certain you'll find it to be cost effective.

This is Swain's website, I have lower overhead :wink: :wink:

https://www.swaintech.com/store.asp?pid=10971

Here's a link to a BMW engine that I coated EVERYTHING: https://www.rfdm.com/gallery/album135?page=28

The coating process (preparation) starts on page 28 of that album, but you're welcome to look at all of it. You might want to keep the link to the entire gallery (>21,647 pictures, at present) in case you suffer from insomnia...

You can contact me directly, if you have any specific questions: erandyforbes@aol.com
 
richberman said:
Randy,
Does the cost per unit drop if the oven is full? :wink: :wink:
I've got a set of pistons too.
Rich
Click to expand...
Nope, just makes for a longer day.

I like to coat the parts as soon as they're blasted, and I like to cook them as soon as they're coated.

More weight in the box just takes longer to reach the setpoint. I always attach the thermocouple to the heaviest part in the oven (sometimes, I just use a block of steel, if all I'm coating are small parts) and the curing cycle (1 hour at the setpoint) doesn't start until the part reaches 300*F.

I don't rely on the oven's thermocouple to tell me how warm the part is, that's what the data logger is for, as well as documentation that a part wasn't overheated.

IMG_3867.sized.jpg


IMG_6007.sized.jpg
 
BlueRidge1 said:
Randy,

Do you install the bottem wiper ring ? I left them off my new pistons. My orginals did not have a bottem groove.

Bob
Click to expand...
I do, but instead of a one (1) piece cast ring, I prefer a three (3) piece low-tension ring set.

Bob (superwrench) was instructed by Total Seal to leave his off; perhaps he'll fill in the details...
 
Total Seal changed my setup and I am now using a low tension oil ring in both grooves. If all you have is the cast ring I wouldn't use one in the bottom groove. What bore size do you have ? I might have a 3 piece oil ring set to give you. Bob {Quick}
 
Bob, SW

Thanks for the offer but I already have it running without the wiper rings. About 1650 miles so far without any ill effects.

Bob G
 
Ed, Think twice about going with 72 spoke wheels. My recollection is that they are quite a bit heavier than the 60 spokers. If it wasn't so late and cold outside I would go out to my storage area and weigh a 60 and a 72 spoke wheel for you. Unsprung weight is not a good thing on a race car. I know, I ran 72 spoke wheels for awhile in the 80s.
 
I've read that the 15x4.5 48 spoke are 7.2kg approx, the 15x6 72 spokes I now run are 10.5kg, and from memory 15x6 alloys 10.2kg.
would like to know if my figs are close or way out, as i thought the alloys were supposed to be a lot lighter!
 
Richard,
I do not think we have an alternative. The 60's last a few seasons and then start to break every time out on the track. The steel can only deal with so many cycles of stretching before they break. I do not like the "busy" look of the 72's nor the extra weight, but we are shooting for a wheel that lasts more then a few years between rebuilds. Our club, the VSCCA, does not allow Minilites, so we have no other choice. I would love to go with a painted Borrani wheel but the costs associated with them are too high....... Unless anyone has a set of used ones they would like to part with......
 
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