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[runsfromdacops]

just got her home. i will pull the motor out tomarow so i can see whats going on in there.

[98vtec]

couldnt it have been heat soak that can bring down power? maybe thats what they were thinking?

i have yet to see heat soak do that much change on the dyno.  Typically very subtle unless you are doing some serious "hot lapping" without shut downs....which isnt exactly smart to begin with.

do you have an oil pressure gauge to moniter?

[narfdanarf]

I wouldn't waste my time with a girdle.

[bigdaddyvtec]

i would.

[Joseph Davis]

The problem with anything spun high is usually the head, but girdle motors simply last longer when making power.  Non-girdle motors make more power, however, at narfy's end of the spectrum 3% more.

[runsfromdacops]

im just going to do the things i NEED to to get the car back up and running. this is just my backup motor any way,i just want to to get me to the end of summer and ill be happy

[98vtec]

The problem with anything spun high is usually the head, but girdle motors simply last longer when making power.  Non-girdle motors make more power, however, at narfy's end of the spectrum 3% more.

rod bolts?  no...?

[BoostedSchemes]

can someone start a separate thread in tech and explain girdles, their pros/cons?

i understand them from an old fart v8 perspective, but i did not think they applied to hondas as much.

but their on the hype motors for a reason i guess.

[Teg2boo]

can someone start a separate thread in tech and explain girdles, their pros/cons?

i understand them from an old fart v8 perspective, but i did not think they applied to hondas as much.

but their on the hype motors for a reason i guess.

I second that.

[runsfromdacops]

can someone start a separate thread in tech and explain girdles, their pros/cons?

i understand them from an old fart v8 perspective, but i did not think they applied to hondas as much.

but their on the hype motors for a reason i guess.

and gsr. if i had one id put it in jsut to be safe but im not going to run out and buy one just becuse

[HiProfile]

Girdles, why?




http://www.epi-eng.com/piston_engine_technology/torsional_excitation_from_piston_engines.htm

Second picture - a normal 4-cyl sees almost 400% of the average torque on that spot of the crank each time the ignition fires. The crank can take the beating and uses the ductility of steel to deform slightly, but an aluminum block isn't a solid chunk. The girdle spreads the load, reducing bearing distortion and movement (both ovaling and overall block twisting). Why do you think the high-displacement, high-rpm K-blocks have a giant girdle, aka lower cassette? Forces square inside an engine relative to RPM, meaning 2x rpm = 4x internal forces.



It also has a bit to do with 2nd-order harmonics (vibrations). Ever notice how inline-4's 2.0L and greater have balance shafts and lots of lower block bracing? Basicly the crank vibrates up & down at twice frequency of the crank (double the rpm). In the first link below, look at the 2nd yellow picture labeled "inline engine". Specifically, look at the difference in length between "a" and "b". In the second link, the 4th graph (fig 9) shows secondary vibration (middle wavy line; note the extra from a poor r/s ratio). The text directly next to fig 2's top explains why. It's sort of a mind-bender, all stemming from a non-infinite cod rod length. That simple detail causes almost all of a inline-4's vibration. :/

http://www.autozine.org/technical_school/engine/smooth2.htm

http://www.epi-eng.com/piston_engine_technology/piston_motion_basics.htm

Oddly enough, "boxer" engines are not vibrationless, and have these same vibrations. They're 180* opposed to each other so they cancel out.

[Joseph Davis]

Oddly enough, "boxer" engines are not vibrationless, and have these same vibrations. They're 180* opposed to each other so they cancel out.

Even Subaru?