Tranny Gearing. Options

[749142]

Hey guys.
does anbydody know about regearing a 914 transmission with a steeper final drive ratio differential. do they make aftermarket differentials? if so any links?
thanks
steven

[Bleyseng]

The final drive/5th gear setup was setup to keep the fan moving at the right speed for cooling.

Changing that for a street car means looking at how you will cool the engine.

[749142]

The final drive/5th gear setup was setup to keep the fan moving at the right speed for cooling.

Changing that for a street car means looking at how you will cool the engine.

my dad has done such extensive polishing to my heads and pistons that my engine runs about 65 degrees cooler than stock. so there for if i can gear it steeper i can get back some of that heat for efficiency and then have more topend if i have the power and have more efficiency becuase of lower rpms. i have video of my heads that are polished. they look like mirrors. you can see the reflection of my dad with the camera in the valves. it took him about 4 months to do the two. but it was well worth it. next best thing from ceramic coating.
steven

[jd74914]

The final drive/5th gear setup was setup to keep the fan moving at the right speed for cooling.

Changing that for a street car means looking at how you will cool the engine.

my dad has done such extensive polishing to my heads and pistons that my engine runs about 65 degrees cooler than stock. so there for if i can gear it steeper i can get back some of that heat for efficiency and then have more topend if i have the power and have more efficiency becuase of lower rpms. i have video of my heads that are polished. they look like mirrors. you can see the reflection of my dad with the camera in the valves. it took him about 4 months to do the two. but it was well worth it. next best thing from ceramic coating.
steven

How do you know it runs cooler than stock?

Polishing does not help you loose heat. If you polish the inside of your ports and combustion chambers you increase surface tension and hurt mixing, and if you polish the outside you loose surface area over the rough castings (heat exchange is dependent on surface area). (IMG:style_emoticons/default/wacko.gif)

[749142]

The final drive/5th gear setup was setup to keep the fan moving at the right speed for cooling.

Changing that for a street car means looking at how you will cool the engine.

my dad has done such extensive polishing to my heads and pistons that my engine runs about 65 degrees cooler than stock. so there for if i can gear it steeper i can get back some of that heat for efficiency and then have more topend if i have the power and have more efficiency becuase of lower rpms. i have video of my heads that are polished. they look like mirrors. you can see the reflection of my dad with the camera in the valves. it took him about 4 months to do the two. but it was well worth it. next best thing from ceramic coating.
steven

How do you know it runs cooler than stock?

Polishing does not help you loose heat. If you polish the inside of your ports and combustion chambers you increase surface tension and hurt mixing, and if you polish the outside you loose surface area over the rough castings (heat exchange is dependent on surface area). (IMG:style_emoticons/default/wacko.gif)

(IMG:style_emoticons/default/WTF.gif)
its just physics. when you polish the chambers. you remove surface area. the casting has peaks and valleys if you stretched those peaks and valleys out its more surface area, which collects more heat. if you remove those peaks and valleys the chambers dont soak up that heat. that heat is therefore used more in pushing the piston instead of being soaked up in the chambers. your right in saying that polishing doesnt help you lose heat, when you polish that extra heat
was never able to be soaked up by the chambers in the first place. and i have seen the results first hand on my car. and im not sure wut you mean by surface tention and hurt mixing?(typo?). polishing the chambers helps keep the engine run cooler but polishing the rough castings on the outside of the head is counterproductive.
steven

[jd74914]

(IMG:style_emoticons/default/WTF.gif)
its just physics. when you polish the chambers. you remove surface area. the casting has peaks and valleys if you stretched those peaks and valleys out its more surface area, which collects more heat. if you remove those peaks and valleys the chambers dont soak up that heat. that heat is therefore used more in pushing the piston instead of being soaked up in the chambers. your right in saying that polishing doesnt help you lose heat, when you polish that extra heat
was never able to be soaked up by the chambers in the first place. and i have seen the results first hand on my car. and im not sure wut you mean by surface tention and hurt mixing?(typo?). polishing the chambers helps keep the engine run cooler but polishing the rough castings on the outside of the head is counterproductive.
steven

I know that polishing will reduce heat into the heads, but it also will create more surface tension which slows down airspeed. The increased air speed and eddy currents cause by a slightly rough texture are important for mixing. While you are keeping more heat in the exhaust you are at the same time impeding mixing. At best its a trade off.

I wouldn't' think my engine has overheated lately (from looking as the valve seats and lack of cracks). I haven't personally run it enough to know. You didn't answer how you definitively know it runs 65* cooler.