Don Terrill’s Speed-Talk

Mark O'Neal wrote: ↑Sat Jun 30, 2018 9:50 pmThere are countries that measure using the metric system...and there is a country that went to the moon, built the most powerful military in history, as well as the largest industrial base ever......

Did the Chinese go to the moon yet? I thought they only had that military guidance satellite installed on the dark side of the moon just on the right orbit.

Here's another question relating to the pin-to-boss overlap. Does the rod small end to pin boss clearance need to be minimal for this kind of small overlaps to survive? My logic is that a lot of exposed pin between the rod small end and the piston pin boss lead to the pin bending and that can't be good with this little overlap between the pin and the pin boss.

.040 per side is our goal.

Rod manufacturers make this difficult.

Mark O'Neal wrote: ↑Thu Nov 28, 2019 4:00 pm .040 per side is our goal. Rod manufacturers make this difficult.

This will get custom rods from a forging intended for 6.2" rods, so I assume we can get whatever small end width we want.

ptuomov wrote: ↑Fri Nov 29, 2019 7:48 am

Mark O'Neal wrote: ↑Thu Nov 28, 2019 4:00 pm .040 per side is our goal. Rod manufacturers make this difficult.

This will get custom rods from a forging intended for 6.2" rods, so I assume we can get whatever small end width we want.

I've seen them from 1.000 to 1.060....so getting the pinboss span from your pistons guy wouldn't be a bad idea. And make sure to beam offset is correct.

Mark O'Neal wrote: ↑Fri Nov 29, 2019 6:10 pm

ptuomov wrote: ↑Fri Nov 29, 2019 7:48 am

Mark O'Neal wrote: ↑Thu Nov 28, 2019 4:00 pm .040 per side is our goal. Rod manufacturers make this difficult.

This will get custom rods from a forging intended for 6.2" rods, so I assume we can get whatever small end width we want.

I've seen them from 1.000 to 1.060....so getting the pinboss span from your pistons guy wouldn't be a bad idea. And make sure to beam offset is correct.

The rod big ends will be asymmetric but the plan is to have the rod bearing mid point under the beam centerline and the beam centerline exactly under the middle of the piston.

So....definitely not a Ford.

Mark O'Neal wrote: ↑Sat Nov 30, 2019 1:47 am So....definitely not a Ford.

No, not a ford.

This is an old and obsolete Porsche V8 from a ‘87 928 S4.

Bore offset is 25mm, journal is 52mm, rod big ends are 27mm wide, stock rods were produced by cutting 2mm off from the one side of symmetric 29mm wide 944 rod. The rod beam is centered relative to the piston and the rod bearing in the front back direction. Stock PPF rods are very strong but also very heavy at 860g for 150mm rod.

GLHS60 wrote: ↑Wed Dec 11, 2019 4:54 pm I believe I can help..

Think of it this way, logically...not some old outdated dictionary definition ..

Engines run on combustible fuel.

Motors run on electricity.

Thanks
Randy

Mark O'Neal wrote: ↑Sun Jul 08, 2018 4:03 amThrice

www.dictionary.com

learn to speak English.

Is this thread turning into a piston wrist pin length measuring contest?

And Randy likes to cruise the lake in his engineboat.

Here's a custom 10mm piston mockup by Mahle and the pin bosses are similarly really skinny. The specified pin is built like a brick house, but it doesn't overlap too much with the pin bosses in the piston!

Photo:

Another picture of 1987 vs 2020:

ptuomov wrote: ↑Fri Jun 29, 2018 7:17 am I’m looking at Mahle 100mm Subaru pistons with 23mm diameter piston wrist pins. The bare piston weighs 406g. The wrist pin is about 57mm long. The gap between pin bosses (for the rod small end) is about 29.5mm. This leaves about 13.75mm (0.54”) of pin inside the piston per side when the pin is perfectly centered. Seems low, no? Must be thoroughly optimized. Welcome to the modern era.

What is the motor's intended use?

LSP wrote: ↑Thu Feb 13, 2020 7:27 am

ptuomov wrote: ↑Fri Jun 29, 2018 7:17 am I’m looking at Mahle 100mm Subaru pistons with 23mm diameter piston wrist pins. The bare piston weighs 406g. The wrist pin is about 57mm long. The gap between pin bosses (for the rod small end) is about 29.5mm. This leaves about 13.75mm (0.54”) of pin inside the piston per side when the pin is perfectly centered. Seems low, no? Must be thoroughly optimized. Welcome to the modern era.

What is the motor's intended use?

Street car, 5.0L, 93 octane pump gas, twin turbo, 8000 rpm fuel cutoff, 78.9mm stroke, probably about 800 lbf-ft torque over a fairly broad power band.

ptuomov wrote: ↑Thu Feb 13, 2020 8:14 am

LSP wrote: ↑Thu Feb 13, 2020 7:27 am

ptuomov wrote: ↑Fri Jun 29, 2018 7:17 am I’m looking at Mahle 100mm Subaru pistons with 23mm diameter piston wrist pins. The bare piston weighs 406g. The wrist pin is about 57mm long. The gap between pin bosses (for the rod small end) is about 29.5mm. This leaves about 13.75mm (0.54”) of pin inside the piston per side when the pin is perfectly centered. Seems low, no? Must be thoroughly optimized. Welcome to the modern era.

What is the motor's intended use?

Street car, 5.0L, 93 octane pump gas, twin turbo, 8000 rpm fuel cutoff, 78.9mm stroke, probably about 800 lbf-ft torque over a fairly broad power band.

Putting Subaru pistons in a V-8?