Hello , Im a new member here . Im working as tunner in my city.
But I don’t have a lot of knowledge and calculation about engine bulding (im working on Normally Aspirated). So Im gonna ask a lot of information from you all of the Honda Master ,and forgive me if I had some language and spelling problem that gonna make some miss communication

im working on my brothers civic fully modified NA ,
this car was for drag racing use, old D13B engine (4 barrel 45mm weber ,complete head job, big Bullfrog 330 degree cams, 4 speed close ratio trans. , etc).
Now im trying to use light weight & knife edge crankshaft for it .
But my senior who ever tried that crank says “Even that would make the engine acceleration better and good to cut the oil ,but the cars would not run better. Because the light crank reduce torque ” . And his car ran only 14.7 sec with the lightweight crank, and goes 14.5s with the standart crank. And also D13b crank only had 4 counterweight , so it was already light enough. If i reduce the weight ,it’ll become “overlight” then loose lot of torque .

Is that True ??????
Im confuse about what crank to go.
explain me about that torque reducing

Regards


Odie Knownothing




[Modified by jt-sport, 2:32 PM 3/8/2002]

 

well iam not sure about the d13's but on most honda engines the crank does not lay in the oil. you would have to take off the oil pan to see if this is true about the d13. hondas use a oil pick up tube usually so it wont be cutting through the oil any better (it will a little better) but the parasitic drag. but lighting the flywheel is safer and does the same effevt. but if you so both parasitic drag sucks and scince this is a drag car doi both.

 

how if we just think about the crankshaft weight,
some says d13 crank that only had 4 counterweight was already light , if i plann to lightening it more (to gain spontaneus engine reving acceleration) will there be "overlight" case that'll reduce the overall torque??




[Modified by jt-sport, 4:16 PM 3/8/2002]

 

Nope. You will free up more by lightening the rotating masses.

 

nah man you can lose tq from a lighten flywheel.

 

Well, you will gain horsepower in the higher RPM's won't you?

I seem shoot off from the mouth a lot. But, most of the time if the conversation is about racing applications then it is stuff that I have heard tech's doing to there machines.

I.E. C5 racing team is limited with restrictor plates and had already ported and polished to the legal limit so to create more power they lightened the load the engine had to use to spin itself. In other words, they got more power by using lighter parts. That is where I got my "Nope. It will create more power" statement from.

 

With a lighter flywheel you lose some off-the-line torque because of the reduced flywheel effect, but will rev more easily due to the decreased rotational mass.

Think of it this way... a heavy flywheel will have a lot of momentum as it spins while you're sitting there waiting to launch. As you engage the clutch the flywheel's momentum is transmitted to the front wheels via the tranmission. Once the clutch is fully engaged, the heavy flywheel is simply additional mass to have to accelerate to speed (proportional to rpm,) which robs some power.

 

wow ,thankss pall !! now im on the way to go with the light crank for this machine..

this lil banger run from 8200 - 9500 at every gear (5 super close tranny), except on the 1st gear to launch.
after i read articles about D series mod. on http://www.theoldone.com/articles/ . It says "we dont need to lightened the crank ,because it not use for above 7500" . and its mean contrary for my purpose above 7500

 

Thankss a lot pallll...
You've all make me confident to planted the lightweight crank
and thats work pretty WILD from 7000 to 9000, and reduce my ET by 0.2 second

NO DOUBT WITH THE LIGHT ONE FOR ALL OUT RACING USE


[Modified by jt-sport, 2:09 PM 3/17/2002]