# Mechanics behind fast revving.... **URL:** \ **Category:** SON240sx Automotive\ **Created:** [November 22, 2005, 8:31am UTC](https://forums.speedlife.net/t/mechanics-behind-fast-revving/90538 "2005-11-22T08:31:02Z")\ **Posts on this page:** 12\ **Page:** 2
**Author:** ![mr200](https://yyz2.discourse-cdn.com/flex034/user_avatar/forums.speedlife.net/mr200/32/5495_2.png) [@mr200](https://forums.speedlife.net/u/mr200)\ **Post date:** [November 25, 2005, 11:37am UTC](https://forums.speedlife.net/t/mechanics-behind-fast-revving/90538/21 "2005-11-25T11:37:09Z")
Not me. The KA is an oversquare engine (long stroke) Long stroke motors don’t want revs. They make torque instead. Plus the KA’s head design isn’t the greatest for high RPM flow. Notice how they fall flat at 5,800? If you want to build a high RPM screamer, I (and I feel dirty saying this) suggest an NA SR20DE … as long as you toss the valvetrain. And put it in something smaller and lighter than an S chassis. ---
**Author:** ![240GTR](https://avatars.discourse-cdn.com/v4/letter/2/8e7dd6/32.png) [@240GTR](https://forums.speedlife.net/u/240GTR)\ **Post date:** [November 25, 2005, 12:44pm UTC](https://forums.speedlife.net/t/mechanics-behind-fast-revving/90538/22 "2005-11-25T12:44:21Z")
> [@mr200](#): > > Not me. > > If you want to build a high RPM screamer, I (and I feel dirty saying this) suggest an NA SR20DE … as long as you toss the valvetrain. > > . LMAO hahahah…I know what you mean so you mean to say…high-revs and torque practically wont come hand in hand (as in the case of civics/prelude etc) or is it due to the oversquare nature of the engine? or did i just repeat myself??? ahhh gotta love working long nights inhaling propane lol i have this possibly idiotic idea in my mind…how about de-stroke a kA24DE and increase compression? ---
**Author:** ![ADAM](https://avatars.discourse-cdn.com/v4/letter/a/4af34b/32.png) [@ADAM](https://forums.speedlife.net/u/ADAM)\ **Post date:** [November 25, 2005, 12:51pm UTC](https://forums.speedlife.net/t/mechanics-behind-fast-revving/90538/23 "2005-11-25T12:51:30Z")
me either… forced induction or displacement is the way to make power… high rev’s are expensive and unreliable ---
**Author:** ![Sasha\_SG](https://yyz2.discourse-cdn.com/flex034/user_avatar/forums.speedlife.net/sasha_sg/32/5477_2.png) [@Sasha\_SG](https://forums.speedlife.net/u/Sasha_SG)\ **Post date:** [November 26, 2005, 12:09am UTC](https://forums.speedlife.net/t/mechanics-behind-fast-revving/90538/24 "2005-11-26T00:09:57Z")
haha adam its soooo true. any motor that revs to 9k all the time needs rebuilds quite often it seems! I figure the faster you have stuff spinning the faster you’ll have stuff breaking. As far as motors that like to rev making torque. HP is simply a calculation of torque. The same torque at a higher RPM will make much more HP, oversquare engines dont like to rev because they have such a long stroke, however this long stroke allows them to make more power. Since they can’t rev, this power is seen mostly as torque (due to low rpm) I hate the SR valvetrain. Such a peice of fucking shit. When i see KA valvetrain i get so jealous. WTF was nissan trying to do here??? ---
**Author:** ![face](https://yyz2.discourse-cdn.com/flex034/user_avatar/forums.speedlife.net/face/32/5504_2.png) [@face](https://forums.speedlife.net/u/face)\ **Post date:** [November 26, 2005, 11:58am UTC](https://forums.speedlife.net/t/mechanics-behind-fast-revving/90538/25 "2005-11-26T11:58:03Z")
very good discussion going on. one thing though, isn’t the ka classified as an undersquare engine? 89mm bore, 96 mm stroke… ---
**Author:** ![240GTR](https://avatars.discourse-cdn.com/v4/letter/2/8e7dd6/32.png) [@240GTR](https://forums.speedlife.net/u/240GTR)\ **Post date:** [November 26, 2005, 12:26pm UTC](https://forums.speedlife.net/t/mechanics-behind-fast-revving/90538/26 "2005-11-26T12:26:45Z")
i’d think it would be an over square (tall rectangle actually but meh) since the stroke will be the height and the bore will be the width ---
**Author:** ![dnash](https://avatars.discourse-cdn.com/v4/letter/d/f6c823/32.png) [@dnash](https://forums.speedlife.net/u/dnash)\ **Post date:** [November 26, 2005, 12:41pm UTC](https://forums.speedlife.net/t/mechanics-behind-fast-revving/90538/27 "2005-11-26T12:41:50Z")
No, it would be undersquare. I don’t know how this term was created but that is what it is. bore\>stroke = oversquare bore\ **Author:** ![240GTR](https://avatars.discourse-cdn.com/v4/letter/2/8e7dd6/32.png) [@240GTR](https://forums.speedlife.net/u/240GTR)\ **Post date:** [November 26, 2005, 12:48pm UTC](https://forums.speedlife.net/t/mechanics-behind-fast-revving/90538/28 "2005-11-26T12:48:05Z") > [@dnash](#): > > No, it would be undersquare. I don’t know how this term was created but that is what it is. > > bore\>stroke = oversquare > bore\ bore=stroke = square > > The proper rod/stroke ratio should be used as well. A long rod engine should rev better then a short rod engine(assuming everything else is equal). Having longer rods increases dwell time at TDC and lessens piston acceleration. thanks for clearing that up… ---
**Author:** ![Solarian](https://yyz2.discourse-cdn.com/flex034/user_avatar/forums.speedlife.net/solarian/32/5514_2.png) [@Solarian](https://forums.speedlife.net/u/Solarian)\ **Post date:** [November 26, 2005, 3:33pm UTC](https://forums.speedlife.net/t/mechanics-behind-fast-revving/90538/29 "2005-11-26T15:33:05Z")
Build a high revving rotary 😉 If you knew that at about 6k rpm the piston accelerates from a stop, past Mach 1, to a stop, and back again, you wouldn’t want a piston engine revving high ever again 😃 ---
**Author:** ![alesserfate](https://avatars.discourse-cdn.com/v4/letter/a/f6c823/32.png) [@alesserfate](https://forums.speedlife.net/u/alesserfate)\ **Post date:** [November 27, 2005, 11:37am UTC](https://forums.speedlife.net/t/mechanics-behind-fast-revving/90538/30 "2005-11-27T11:37:34Z")
:wackit: mach1… anyway than is the engine in the 86 in initial d that revvs to 11k all bullshit ? ---
**Author:** ![Sasha\_SG](https://yyz2.discourse-cdn.com/flex034/user_avatar/forums.speedlife.net/sasha_sg/32/5477_2.png) [@Sasha\_SG](https://forums.speedlife.net/u/Sasha_SG)\ **Post date:** [November 27, 2005, 11:48am UTC](https://forums.speedlife.net/t/mechanics-behind-fast-revving/90538/31 "2005-11-27T11:48:37Z")
nah, bike motors rev to 14-15k and come stock. I dont know the exact physics formula but i asked this back in grade 12 and basically the more weight you add the force on it goes exponentially up or some shit. so the heavier a motor, even at the same rpm the forces inside are not proportianally higher. So say you have a 50% bigger motor that is about 50% stronger, well now you have like 4times more force on that peice that is only 50% stronger. so you cant rev as high anymore ---
**Author:** ![ADAM](https://avatars.discourse-cdn.com/v4/letter/a/4af34b/32.png) [@ADAM](https://forums.speedlife.net/u/ADAM)\ **Post date:** [November 28, 2005, 6:17am UTC](https://forums.speedlife.net/t/mechanics-behind-fast-revving/90538/32 "2005-11-28T06:17:21Z")
this is the reason why displacement and forced induction are better in a crux… revs increase the load EXPONENTIALLY forced induction increases the load linerally…due to the angle of the piston to the crank and when power is being applied through the stroke of the engine… these are two vastly different type stresses… [Previous page](https://forums.speedlife.net/t/mechanics-behind-fast-revving/90538.md?page=1)