how to read dyno chart?

TE27levin

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why some ppl run adjustable pulley at 20v run faster?
how we make our car run faster?
20v is a high rev engine, to make it run faster we need to push all the power band according to the engine's habits.

this taken from http://turbomagazine.com/tech/0304tur_chart/

""
Powerband Identification
When you're driving your car in a spirited fashion, what's the engine doing? When you shift, where does the tach needle fall? Using our Project Code Name SE-R (the project car formerly known as SE-Rious Sentra) as an example, let's get a rundown on the revving habits of its SR20DE.

This is pretty straightforward. Get on the throttle until 7000 rpm and shift. Eyeing the tach, we observed the needle drop to 5100 rpm. Shifting at 6500 rpm netted a drop to 4900 rpm. So our engine's "sweet spot" is in the 5000-rpm to 7000-rpm range. This fact is proven on the dyno, where we see the power curve develop a real aggressive arc at this point in the pull.

Parts Have Power Targets
Now that you understand the habits of your engine, you need to know what to expect from the parts you add-not just how much power they generate, but where in your engine's powerband this power will be realized.

For instance, there are what can be called efficiency parts like intakes, headers, high-flow cats and exhaust systems that address restrictions in the OEM components they replace. This type of component should impact top-end power. Since a restriction becomes more apparent the higher the engine revs, these performance parts see gains in the mid to high ranges.

Cams are a different animal. The design of a cam's lobes dictate where in the powerband the bumpstick will make power. A more aggressive grind translates into a cam that delivers the goods higher in the rev range. Looking to get cams for your street car? A set of race cams designed to make power from 7500 rpm to 9000 rpm would be a disaster.

Talk to the manufacturer about where its cams will make power and be sure the bumpsticks you buy match your engine's behavior.

Power pulleys make power constantly. By virtue of weighing less, their reduction of rotating inertia is evident at all engine speeds, so the curve is merely bumped up in a proportionally equal amount throughout the measurable powerband. This proportional phenomenon can also be seen in some ECU ROM tunes that optimize the performance of a collection of components.

Turbos make power everywhere, but turbine housing size and wheel trim will affect how quickly the peak is reached. The maximum boost and efficiency of the compressor wheel will also affect the ultimate power produced by the system.

Factors such as intercooling efficiency, fuel enrichment capabilities and tuning will also be felt on the bottom line. The dyno graph allows the tuner to see how quickly the boost is being made, how much power is being made so he can make changes to A/R ratios, compressor wheels or entire turbos to realize the correct power curve for a given engine.
 
but many want a street driveable car...so dun wan to set everything for high RPM neh....if power between 6k-8k how to drive on street...traffic jam...wan to fast oso kenot...

but for racing different story
 
Originally posted by TE27levin@Mar 15 2005, 14:03
to make it run faster we need to push all the power band according to the engine's habits.
yin yang theory - very good :)
 
cam lobes.. hmm.. some sifoo please verify this for me, dunno correct or not my understanding:

degree of the cam lobes determine the duration of the opening of the valve

the higher the degree, the longer the valve will open

if the engine runs very slow, the best time for the valve to open is when the piston hits the top end and start to move down. and the best time to close is when the piston hits the bottom end and start to move up. Its because the air manage to go in fast enough and open and close like that can suck in the most air.

but in reality engine move very fast. and like what acoustic said sometime ago, forget when, that air is "stupid" it will keep on rushing in because of the air velocity.

if the engine moves fast, closing the valve sooner (short duration cam) will cause the engine to suck in less air, cuz the air tak sempat masuk.

thats why high reving engine use high duration cam to get more power. opening the valve for a longer period of time and close much later, so that more air can be suck in because of the air velocity/vacuum in combustion chamber (cuz air tak sempat masuk, so even if the piston hit bottom end there's still vacumm inside).

high duration cam makes more power than retarding cam timing because retard timing makes valve close later, but also make it open later. high duration cam can open earlier and close later, so more air come in.

reason why racing cam with high duration don't make power at low rev is because it close so late, the air manage to fill the combustion chamber, but the valve don't close, which result in the air pushed back into the intake manifold..

turbo make power at low rev or high rev, as long as the turbo's size is correct. this is why most (if not all) force induction user uses low duration high lift cam. this is because the air is pumped inside, not suck in by the vacuum. so with a cam that make the valve close nearly after the piston hit the bottom end, the turbine can pump in most air into the chamber. The high lift cam is to let more air come in easier.


----------------------disclaimer------------------------
i'm not trying to say anything or give info... before i get flame for nothing.. i wan to say i just want verification on what i understand so far... :ph34r: and hope can correct what i misunderstood... only do some reading on intake cam so far.. haven't understand exhaust cam much yet :(
 
yes..good explanation.........
read about overlap..and you will understand about the exhaust cam.....
 
i read abt overlap from a web tht explains abt VTEC oso....forgot where liao

slightly higher duration cam for turbo will oso increase lots of hp...
see them using abt 10++ degrees hinger duration cam from stock's for intake edi add up so much hp...
turbo can still pump in a large ammount of air even whn the piston is already starting to move up frm BDC.
 
but extreamly high duration cam isn't very good for turbo right? never heard anybody with 300+ degree cam on turbo engine
 
The thread doesn't really tell u how to read dyno chart at all, rather how to make more horses ;)

rollakid said:
reason why racing cam with high duration don't make power at low rev is because it close so late, the air manage to fill the combustion chamber, but the valve don't close, which result in the air pushed back into the intake manifold..

To add with my own (primitive) understanding of how camshaft works, u can indirectly said air being pushed back into intake manifold (at low RPM, for racing cams), is equal to loss of compression ratio at low-RPMs (less air in combustion chamber). That's why engines with racing cams normally have their static compression ratio increased, to compensate this kind of loss.

I guess understanding valve timing concepts and how racing cams make power is like learning a fizik class, I only understood it recently too :p
 
Te27, 35 psi boost, not scared meh, long term life span ???

I just played at a hill somewhere, very clean, very bright, very little traffic, very wide, not dangerous at all, around 50 corners one way, only a few are cliffs, all corners have natural mountain wall barrier so won't fall off one.

Go up hill around 6:30 and go down hill also around 6:30. The timing is not 100% accurate because the starting line was not determined, the end line also not determine.

Considering the fact of uphill same as downhill means my skill through the same corner is the same speed, hence nearly same time. This is such a shame, I feel very discourage and does not deserve to increase engine power anymore :(

The limit is myself :( - how to break??? it has been like this for many years ???
 

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