JAM* Spec Venolia forged pistons.........simply the best.
Sep 8, 2008, 06:52 AM
#19
Evolving Member
iTrader: (1)
Join Date: Sep 2007
Location: AZ
Posts: 211
Likes: 0
Received 0 Likes
on
0 Posts
was great before i left though. hope its great when i get back.
Be back from Iraq in Nov
Sep 8, 2008, 12:29 PM
#21
Former Sponsor
Thread Starter
iTrader: (9)
Join Date: Aug 2006
Location: Maryland
Posts: 283
Likes: 0
Received 0 Likes
on
0 Posts
Glad to hear it Richard. Stay safe over there in the sandbox
These are the same pistons that we use in all of our Stage 3 and soon to be released Stage 4 Full Race shortblocks.
The procedures that go into our shortblocks are outlined in this thread;
https://www.evolutionm.net/forums/sh...jam+shortblock
Sep 8, 2008, 02:25 PM
#22
I usually refrain from making negative comments on the forums, but this piston looks like it was made by Henry Ford in the 1920’s. I'm not attacking JAM (your products/services have a good reputation), but am very surprised at this piston design.
1. Top land: The top land looks to be over .400" thick. This is ridiculously thick and will hurt efficiency. I can't think of an application (other than maybe Nitro methane) that would require a top land thickness like that. Most manufactures (including OEM) can safely run between .180" and .280" without problems.
2. Skirt length: What’s with the long skirt? The piston can be stable in the bore without a long tail on the skirt. No piston manufacturer other than Venolia or Arias has used that old school “technology” in current piston designs since decades ago.
3. Skirt grooves: The grooves in the skirt for “oil retention” are unnecessary and do nothing but collect oil/carbon and help transfer material to the cylinder wall. Way Old School.
4. Wrist pins: Considering this piston probably weighs close to 400 grams (very heavy), I hope the wrist pin has at least .180” of wall thickness. The wrist pin is NOT the place to save weight, especially in a 4 cylinder engine that turns well over 7000 rpm. It may be the picture, but it looks very thin.
5. Buttons: Why buttons? A wire lock works great.
6. 2618 alloy: Most manufactures use 2618.
7. Forced pin oiling: This is a standard feature on 90% of aftermarket pistons available today.
8. Full round forging vs. Slipper Skirt Style forging: Most turbo pistons are made a full round style forging, but "slipper skirt" forgings have proven reliable in application above 4hp per cubic inch. This is misinformation.
This piston really isn’t superior to any others on the market. Venolia is a small piston manufacturer that primarily makes big, heavy pistons. Their engineering capability is limited at best. I’m not saying JAM is a bad, only this piston.
1. Top land: The top land looks to be over .400" thick. This is ridiculously thick and will hurt efficiency. I can't think of an application (other than maybe Nitro methane) that would require a top land thickness like that. Most manufactures (including OEM) can safely run between .180" and .280" without problems.
2. Skirt length: What’s with the long skirt? The piston can be stable in the bore without a long tail on the skirt. No piston manufacturer other than Venolia or Arias has used that old school “technology” in current piston designs since decades ago.
3. Skirt grooves: The grooves in the skirt for “oil retention” are unnecessary and do nothing but collect oil/carbon and help transfer material to the cylinder wall. Way Old School.
4. Wrist pins: Considering this piston probably weighs close to 400 grams (very heavy), I hope the wrist pin has at least .180” of wall thickness. The wrist pin is NOT the place to save weight, especially in a 4 cylinder engine that turns well over 7000 rpm. It may be the picture, but it looks very thin.
5. Buttons: Why buttons? A wire lock works great.
6. 2618 alloy: Most manufactures use 2618.
7. Forced pin oiling: This is a standard feature on 90% of aftermarket pistons available today.
8. Full round forging vs. Slipper Skirt Style forging: Most turbo pistons are made a full round style forging, but "slipper skirt" forgings have proven reliable in application above 4hp per cubic inch. This is misinformation.
This piston really isn’t superior to any others on the market. Venolia is a small piston manufacturer that primarily makes big, heavy pistons. Their engineering capability is limited at best. I’m not saying JAM is a bad, only this piston.
Sep 8, 2008, 05:46 PM
#24
Former Sponsor
Thread Starter
iTrader: (9)
Join Date: Aug 2006
Location: Maryland
Posts: 283
Likes: 0
Received 0 Likes
on
0 Posts
I will address your points and try to avoid a pissing contest here. Let's try and keep this purely technical. If you have anything to add please feel free to PM or call me 410-859-3269
The top land is positioned farther away from the crown of the piston to isolate the top ring from the excessive heat in the chamber from high boost and unleaded fuels. The .180" will not hold up in a high boost application for any extended period of time.
The skirt isn't as long as it appears to be. The photo is deceiving. The length is comparable to the OEM piece. It can't be any longer because then there would be clearance issues with the crank, oilers AND rods.
Incorrect. The grooves are designed for oil retention and is not detrimental as you imply. The thin film of oil serves to supress noise (piston slap) during cold start and DECREASES the wear on the cylinder walls due to the added lubrication. They do NOT collect carbon! Blatant misinformation. How do you end up with carbon past the rings if they're sealing properly? Sound like a result of poor piston design to me.
Everything about the pins is designed for strength. The material has been moved to the highest load bearing area which is the center. Please go back and read the thread. This is called "taper boring" or "taper walled".
Please go back and read the original post again. The buttons are NOT for pin retention. They are used in place of an oil support rail on stroker pistons where the pin intersects the oil ring groove. We use a spiral lock for pin retention. This is FAR superior to a wire lock. More misinformation.
Yes, but not all. It is a feature of the piston that is worth mentioning and describing the benefits of.
You are correct, however it's not true forced oiling. Most of the pistons that we've seen come through the shop have the oil hole in the bottom of the pin bore which creates a weak spot in the most critical area and also inhibits proper lubrication and engine life. The Venolia forces pressurized oil between the pin and bore.
But for how long? I can make 1000hp with just about any parts on the market but what we're after here is high HP AND longevity. You can't win a race if you can't finish a race.
You couldn't be farther from right. Venolia is a HUGE manufacturer that supplies pistons to all forms of racing around the world. Just because you don't know what they do, how they do it and why it's done is no reason for you to make derogatory, slanderous comments towards their products. They aren't as widely known as some of the other companies because they don't offer a shelf piston and don't sell to the general public. Don't use this as ammunition against them.
I usually refrain from making negative comments on the forums, but this piston looks like it was made by Henry Ford in the 1920’s. I'm not attacking JAM (your products/services have a good reputation), but am very surprised at this piston design.
1. Top land: The top land looks to be over .400" thick. This is ridiculously thick and will hurt efficiency. I can't think of an application (other than maybe Nitro methane) that would require a top land thickness like that. Most manufactures (including OEM) can safely run between .180" and .280" without problems.
1. Top land: The top land looks to be over .400" thick. This is ridiculously thick and will hurt efficiency. I can't think of an application (other than maybe Nitro methane) that would require a top land thickness like that. Most manufactures (including OEM) can safely run between .180" and .280" without problems.
4. Wrist pins: Considering this piston probably weighs close to 400 grams (very heavy), I hope the wrist pin has at least .180” of wall thickness. The wrist pin is NOT the place to save weight, especially in a 4 cylinder engine that turns well over 7000 rpm. It may be the picture, but it looks very thin.
Please go back and read the original post again. The buttons are NOT for pin retention. They are used in place of an oil support rail on stroker pistons where the pin intersects the oil ring groove. We use a spiral lock for pin retention. This is FAR superior to a wire lock. More misinformation.
Yes, but not all. It is a feature of the piston that is worth mentioning and describing the benefits of.
You couldn't be farther from right. Venolia is a HUGE manufacturer that supplies pistons to all forms of racing around the world. Just because you don't know what they do, how they do it and why it's done is no reason for you to make derogatory, slanderous comments towards their products. They aren't as widely known as some of the other companies because they don't offer a shelf piston and don't sell to the general public. Don't use this as ammunition against them.
