duration and rpm ranges...

[KiD-ViD]

yes this is a question about an L6 but I think there are alot of people here who know quite abit about engine formulas and whatnot.(*cough* grumpy *cough*) anway...I am looking for a formula that would be able to tell me about where peak power would be depending on duration. I plug the msa cams into desktop dyno and they come out about 8k peak power and it just doesent seem right to me for a cam with 270/280 duration on the L6. I would like power to peak at either 6500 or 7000 on this engine. thanks alot guys.

[Mudge]

It will also depend on lobe profile, remember the cam is the most complex item in the engine, practically a "brain" if you will.

 

Desktop Dyno requires full cam specs (other than lobe data, it just guesses), this means you need .050" info, 270/280 @ .050" WOULD be a revver, but realistically a 270 intake on an L6 cam is what a 220 or 230 @ .050"?

 

For something to peak at 6500 you'll be shifting above that, so that when you drop into your next gear your not outside of your powerband, so you can do calculations on that also. I'd look at a 230 intake approximately if your going to rev it out, and thats about as big as I think I'd go from what others say about cams on these cars, they already aren't making monster torque but at least they are light. If its a stock bottom car I would be hesitant to take it past 6500 myself, but I dont like unexpected supprises, some people get lucky some dont.

[KiD-ViD]

oh ya I forgot they are going to do it at advertised and not at .050. also, I was planning to shift at 7500 or 7000 so I wanted peak at 7k or 6500. I will prolly go with the latter of the two. as for the bottom end I was planning on completely rebuilding it and lightening, balancing, and peening the internals. besides whats the worst that could happen? shattered crank? rod through the wall? just go to the junk yard and pick up another for $60 thanks for the insight. I will try it again on desktop dyno when I get home from work. still looking for that magic formula though.

[Mudge]

True, the engines are somewhat cheap, its labor intensive to swap though and yada yada. Rebuild is definately a good idea, I dont know what RPM the stock crank will take - but full floating rods would be a nice idea, Grump has a post about it in fact, stock L6 has pressed stuff.

 

If that is 270/280 @ .050" then I have a hard time believing its all over at 7k RPM, that is huge, at least its solid but still that is a nutso size. I'd look at 245-255 if your looking to stick in the 7k RPM range, JMO though

[KiD-ViD]

I just tried it on desktop dyno and im still lost...I think it is good for roughly estimating power and power changes with different parts ('specially v8s) but it just doesent do small motors well. if I set the duration at 210 @ .050 it still comes up with peak power at 7500...that just doesent seem right. I will try to find a formula somewhere or somthing else to compare it to

 

if an l24 makes 130 @ 6000 with 248 duration then with ~270 it would make peak power at ~7000...but that isnt the case in desktop dyno

[Mudge]

Peak power comes way before 6000 RPM.

[grumpyvette]

"I would like power to peak at either 6500 or 7000 on this engine. thanks alot guys."

 

thats going to require a cam of about 255-265 duration@.050 lift on the intake, and cams like that don,t run worth crap at rpm level lower than about 3500rpm unless your turbocharged (NOT A GOOD STREET COMBO!)

 

 

 

 

 

while this chart is designed to show the older sbc and the older design heads its still close to correct for the newer design engine or for that matter most other engines because the main factor is THE AVAILABLE TIME THAT THE VALVES REMAIN OPEN IN RELATION TO THE RPM

 

BUT ID LIKE TO POINT OUT THAT SIX CYLINDER DATSUN ENGINES DON,T NORMALLY RUN UP MORE THAN ABOUT 6000RPM AT PEAK POWER

THIS CRANE CAM IS A BETTER CHOICE

 

Grind Number Part Number

DA-282-2-10

168-0014

 

Advertised Duration

Int/Exh Duration @ .050

Int/Exh Lobe Separation Gross Lift

282 / 292 236/246 110 450/450