Another Stihl 460 build

[Rich Fife]

Dimpled Pistons Use Golf Tech to Improve Diesel Power, Efficiency

Speed of Air claims their dimpled pistons make more power and reduce particulate emissions of diesel engines, and have the data to back their claim up.

www.motortrend.com

I was sent this link moment's ago.

 

[thompsoncustom]

Dimpled Pistons Use Golf Tech to Improve Diesel Power, Efficiency

Speed of Air claims their dimpled pistons make more power and reduce particulate emissions of diesel engines, and have the data to back their claim up.

www.motortrend.com

I was sent this link moment's ago.

Well only one way to find out

 

[Rich Fife]

Well only one way to find out

Exactly

 

[thompsoncustom]

Something I didn't see mentioned was the under side of the piston, I would think that would be just as important to reduce drag when the piston is headed up. Looks like a fun piston mod might have to try it sometime.

 

[Wonkydonkey]

I'm not sure If I’m on the right page or not ? Is this a woods, irons, wedge & putters thread ?

But anyhow I thought the squish is lost fuel in the combustion and there’s something important about it’s velocity as well.

I can’t remember if it was Bell or Jennings

 

[Rich Fife]

I'm not sure If I’m on the right page or not ? Is this a woods, irons, wedge & putters thread ?

Yep, you're % on the wrong page. We don't build saws to cut, we build them to chip. Like golf. I'm assuming your golf game is weak?
I can hit a nasty slice, straight into the other fairway.

 

[Rich Fife]

Something I didn't see mentioned was the under side of the piston, I would think that would be just as important to reduce drag when the piston is headed up. Looks like a fun piston mod might have to try it sometime.

Idk... I think there's too many obstructions in that area to put any thought into it.

 

[thompsoncustom]

Idk... I think there's too many obstructions in that area to put any thought into it.

ya trying to dimple that area sounds terrible but that's where the drag would be kind of like the back of a semi trailer. those weird panels on the back of some trailers improve fuel mileage by 5%

 

[Rich Fife]

ya trying to dimple that area sounds terrible but that's where the drag would be

agreed.

kind of like the back of a semi trailer. those weird panels on the back of some trailers improve fuel mileage by 5%

I figured those panels were for airflow, but, I always wondered if they helped and if so, to what degree. Definitely interesting for sure.

 

[srcarr52]

Next up was the cylinder... and jamming out to CCR.

I rarely find a cylinder that has the flange perfectly orthogonal to the bore. Having a dial on the flange is good to get you really close, but like you said in the video, you better check top and bottom of the bore for your final dial in.

 

[srcarr52]

ya trying to dimple that area sounds terrible but that's where the drag would be kind of like the back of a semi trailer. those weird panels on the back of some trailers improve fuel mileage by 5%

Those are to smooth the air flow after the trailer to decrease the low pressure region which is where the majority of the drag comes from. Dimples are more like the vortex generators (inverted naca ducts) at the back of the sleeper to keep the flow attached down the trailer. Sometimes you'll see another row of them at the end of the trailer.

 

[timg]

Love it when talented machinist and car chiefs share their thoughts. Keep this thread going guys. In your scenario Shaun both hats fit you well. So on a late model or modified the extended tail sections of the side panels have dual purposes? Both to catch the air into the turn and also reduce the low pressure area on the rear? Interesting.

 

[srcarr52]

Love it when talented machinist and car chiefs share their thoughts. Keep this thread going guys. In your scenario Shaun both hats fit you well. So on a late model or modified the extended tail sections of the side panels have dual purposes? Both to catch the air into the turn and also reduce the low pressure area on the rear? Interesting.

Do you mean the spoiler sides?

 

[Rich Fife]

I rarely find a cylinder that has the flange perfectly orthogonal to the bore. Having a dial on the flange is good to get you really close, but like you said in the video, you better check top and bottom of the bore for your final dial in.

The worst cylinder that I came across had to have been made on either an early Monday morning or Late Friday night.... either way, it was F'd... the base to bore reference was insanely out from being perpendicular... it was enough to where I had to use the squishband and 4 point that because Even the squishband was funky.... that was my 1st bad experience with a Chinese 660 cylinder...

 

[Rich Fife]

Those are to smooth the air flow after the trailer to decrease the low pressure region which is where the majority of the drag comes from. Dimples are more like the vortex generators (inverted naca ducts) at the back of the sleeper to keep the flow attached down the trailer. Sometimes you'll see another row of them at the end of the trailer.

I love how simple remedies yield positive results.

 

[huskihl]

The worst cylinder that I came across had to have been made on either an early Monday morning or Late Friday night.... either way, it was F'd... the base to bore reference was insanely out from being perpendicular... it was enough to where I had to use the squishband and 4 point that because Even the squishband was funky.... that was my 1st bad experience with a Chinese 660 cylinder...

If you’re cutting the base though, the only thing that matters is the X and Y axis on the cylinder wall. If you’re not cutting the squish, there’s nothing you can do about it.

 

[Rich Fife]

Do you mean the spoiler sides?

We played around with our spoilers on our race cars... angles, heights and we even angled our spoiler in the sense that the RR spoiler had a lesser degree than left side... in my mind, it changed the downforce on the rear section of the Decking...

 

[Rich Fife]

If you’re cutting the base though, the only thing that matters is the X and Y axis on the cylinder wall. If you’re not cutting the squish, there’s nothing you can do about it.

For me, It's the small things that "should be" right, that aren't... that send my OCD though the roof. over the years, I've been dialing/throttling that $h!t back but, sometimes... that stupid *s-word flares it up...

 

[huskihl]

For me, It's the small things that "should be" right, that aren't... that send my OCD though the roof. over the years, I've been dialing/throttling that $h!t back but, sometimes... that stupid *s-word flares it up...

I get that. But if it doesn’t matter because you’re cutting the base anyway…

 

[srcarr52]

We played around with our spoilers on our race cars... angles, heights and we even angled our spoiler in the sense that the RR spoiler had a lesser degree than left side... in my mind, it changed the downforce on the rear section of the Decking...

It would have lessened the downforce on the right side of the deck some and maybe decreased the drag.

Here is about the only published cfd results for dirt cars, notice the name on the nose!

Simulating a Dirt Late Model Racing Car in CFD - Advanced CFD Technology Engineering Experts - TotalSim

TotalSim has completed an aerodynamic analysis of a Dirt Late Model using CFD showing how these cars are able to corner at high speed on slippery tracks

www.totalsim.us