Spark Plug Heat ranges, what gains have you made?

[Stan Weiss]

Originally Posted by MoJo Risen

Thats approximately 2.5% gain?

There is more potential HP in a corrected Piston pin offset.

I'm glad we all know now that NHRA DOES NOT TECH THIS FEATURE.

Remember it is not one size does the same for all. This is a 426 ci Chrysler with the same 0.06" offset.

Bore = 4.25 Stroke = 3.75 Rod Length = 6.768 RPM = 6500
Wrist Pin Offset = 0.06
Actual Piston Stroke 3.75015962277
Cylinder Volume 53.200718 CI 871.803575 cc
Engine Size 425.605745 CI 6974.428599 cc
Crank Angle Piston TDC -0.39775244513 Piston BDC 179.29739772523

Stan

[pmrphil]

Wasn't the Boss 302 a dome piston? Can't put that in backwards.

[MoJo Risen]

Originally Posted by pmrphil

Wasn't the Boss 302 a dome piston? Can't put that in backwards.

No need to do that, any stocker can Submit their own piston for the class.

[Bruce Fulper]

Originally Posted by Rob Petrie E395

David Frieburger (might be spelled wrong) from Hot Rod magazine, engine masters, road kill ect ect. Just posted within the last couple of days that they tried the reverse piston trick on a 360. They saw no changes on the Dyno.

Fryburger....hahahahaha.

[Bruce Fulper]

Originally Posted by MoJo Risen

Enhanced tune for my vehicle is, running ignition Timing right on the edge of pre ignition.

"on the edge of pre ignition" ?? Detonation and pre ignition are two very different things. Pretty sure you meant detonation.

[MoJo Risen]

Originally Posted by Bruce Fulper

"on the edge of pre ignition" ?? Detonation and pre ignition are two very different things. Pretty sure you meant detonation.

No Bruce, it's a TURBO car, high Combustion pressure.

Turbo cars have a tendency to have low speed Pre ignition with much higher Combustion pressure....

But, I am here to gather ideas and have looked further into detonation.
I can see how they can be confused with one another.
Thank you for the response.

I do look forward to the NGK heat range 9 plug to test.

[GTOMayhem]

Originally Posted by Stan Weiss

A wrist pin offset normally is 0.060" to 0.080". When people reverse the wrist pin offset (do people still do this in stock?) this moves the pin center line 0.120" to 0.160" they may see a very small difference. Lets look at a 0.060" reverse and we a talking a little under 1 degree change in Piston TDC to crank journal TDC

Bore = 4.0 Stroke = 3.25 Rod Length = 5.7
Actual Piston Stroke 3.25019600382
Cylinder Volume 40.843168 CI 669.299602 cc
Engine Size 326.745340 CI 5354.396814 cc

Wrist Pin Offset = 0.06
Crank Angle Piston TDC -0.46932221356 Piston BDC 179.15635067565

Wrist Pin Offset = -0.06
Crank Angle Piston TDC 0.46932221356 Piston BDC 180.84364932435

Where you can really see a difference is with an inline motorcycle engine where the crank line has been moved 10 mm.

Stan

Help us slow ones out a little bit. What exactly am I looking at and how would it affect power?


Rick Thomason
GTOMayhem

[Stan Weiss]

When you add wrist pin offset a number of thinks happen. The piston and the crank rod journal are not ATDC and BBDC at the same time. Now based on which way you have the offset decides if piston TDC is before or after crank rod journal TDC. Another thing that happens is all 4 cycle are not long 90 degrees each. 2 become less and 2 become more. Again which 2 do what is based on where the offset was placed.The is also a very very small change in stroke and displacement. (For inline engines where you can move / offset the crank center line these can be larger).


Stan

[Greg Reimer 7376]

In light of all this study of the laws of physics, what does the installation of an offset pin piston have on piston to valve clearance ? Sounds like a way to close up excessive clearance on one valve while opening it up on others. Or, like so many things out there, is it significant or just one more gnat to swat at?

[Stan Weiss]

Originally Posted by Greg Reimer 7376

In light of all this study of the laws of physics, what does the installation of an offset pin piston have on piston to valve clearance ? Sounds like a way to close up excessive clearance on one valve while opening it up on others. Or, like so many things out there, is it significant or just one more gnat to swat at?

Within a normal range of piston pin offset the piston travel curve does not change very much from centered. So if you are using piston TDC there should be almost no difference in VTP clearance because of wrist pin offset.


Stan


PS Above I am talking about if you degree the cam. If someone just installs the cam dot to dot (crank rod journal TDC?) There will be more of a change in VTP clearance from the offset over centered pin.


Stan