mokompri

btw, doesnt the rb20 have HLA's ? afaik only the rb26 runs solid lifters right ? the HLA's are the problem with high revs on an sr20, not the rocker arm system.. im pretty sure f1 engines ran rocker arms at one stage did they not

this thread was never serious, i dont know why some people get so worked up over nothing :sorcerer: sau emoticons ftw !

of all the years ive been in the silvia scene, i only know of 1 broken rocker. whats wrong with the chain drive ?! not surprisingly there is alot of bias here

scavenging occurs in the 'tuned'/extractors part of the exhaust, and yes as i already mentioned it is more important to have properly timed pulses over all out flow. the cat-back however has no effect on scavenging, the more free flowing the better.

point taken cheapie manifolds off the shelf are cheap as chips these days, and add all those extra accessories on top would still be under the cost of an extra turbo me thinks ! but i could be wrong

roy, i thought the general consensus was that the sr20 was the more responsive of the 2 certainly i hear alot about the dreaded lag of the rb20.. although im biased, but no more then you !

how many awkw is needed for a 10 sec pass in a gtr anyways ?

im pretty sure i saw a stock turbo'd xr6t do a 10second pass (article on autospeed i think). 20K is over the top, if you put it together yourself you could do it under 10K easy. why has everyone gone for twins on a 'cheap' drag setup ? go for a big single (garrett off the shelf). injectors, map sensor PFC, clutch, exhaust and ALOT of nos. i rekon you MIGHT just scrape in under 5K, with some second hand parts

i cant comment on a car i dont have personal experience with.. but i can name an n/a 2L silvia that went from 2.5" to 3" cat back and gained everywhere in the rev range, how do you explain that? you cant and theres no point in trying because you know nothing about the car other then the small bit of information i have given you. but heres some food for thought. alot of carby cars can easily lose power after swapping to a higher flowing exhaust. the reason for this is quite simple, fitting a higher flowing exhaust changes the breathing characteristics of the engine, often to a point where the mixtures set by jetting on the carby are no longer optimal for the new 'setup', this caused a loss of power. of course re-jetting and retuning of the car, would then see an increase in power from its previous state. Another example is the late model wrx. the ecu of these cars did not cope well with changes to the airflow of the engine, and as such what would happen is after fitting an exhaust people found no gain up top. how do you explain that ? turbo cars always gain from a more free flowing exhaust dont they ? well its simply because the ecu noticed the increase in airflow and thinks there is something wrong, and does the equivalent of a nissan 'rich and retard'. with ecu tuning, these problems are all solved. im not saying this is what happened in that circumstance, but im saying your lacking information and im certain that a 'lack' of backpressure wasnt the problem. i think YOU should be the one reading some autospeed articles, i actually have had a subscription for quite some time and know that they take the same position as i do in regards to backpressure in exhausts. as djr pointed out, backpressure reduces from a temperature reduction. here are the common gas laws V = kT P = kT PV = k V = volume P = pressure T = temperature k = a constant of proportionality you can see that, with a reduction in temperature, with a fixed volume (which is the exhaust pipe, because the gas will always fill it), you get a reduction in pressure/backpressure. theres no 2 ways about it. a pipes capacity to move mass is whats important, because each combustion cycle produces the same amount of mass, what changes is only the temperature and density. yes, energy is lost by loss of heat which slows down the gas, but this is outweighed by increased mass the exhaust can flow due to the colder gas, this is shown by this equation: speed = kinetic energy^0.5 (the kelvin temperature is directly proportional to the kinetic energy of a gas). no matter what numbers you plug in, you will always get more mass of gas flow with a lower temperature, which gives less backpressure.

i agree with djr.. in simple terms, with a lighter flywheel there is less rotational mass to move, thus meaning it requires less energy/power/throttle to spin. with everything else constant, this means there is less mass for the engine to deal with pushing the car up the hill, this means less throttle required. now where a heavier flywheel WOULD help on the uphill, would be if you were simply coasting up and NOT applying throttle, because you have more stored energy to use up, your car has more momentum/inertia and i think this is where people are confusing seat of pants results with whats really happening. under a certain rpm the car wont be making enough power to accelerate uphill, and will continously lose rpm, and so requiring a downshift, because there is less momentum/inertia, rpm's will drop faster and therefore you will need more throttle and rpm to keep yourself in the usable rpm range after you clutch it in and change gears. so a heavier flywheel also helps changing gears on the uphill. but this shouldnt be confused, with how much energy/throttle is required to move the car at x rpm on a certain hill, the lighter flywheel will always require less. not necessarily, it doesnt hold true as an absolute statement. a longer intake *can* give better intake velocities up top which will increase VE (sometimes over 100%), giving more power. theres a balance between restriction and length which has to be made, but its quite easy to reverse the logic of what you have said in a proper setup. i have to strongly disagree. with exhausts, its a matter of attaining the least amount of restriction, after the 'tuned' extractor section of exhaust. backpressure by definition is something that pushes against the cylinder coming up to TDC, and causes a loss of power, this is simple physics, backpressure is not desirable, EVER (not counting 2 strokes ). the velocity is simply a side effect of pressure in the exhaust, so if the gas is just 'sitting' there, it means there isnt that much pressure in the exhaust relative to its size, BUT this isnt a bad thing, it just means there is low backpressure, which is GOOD. in extractors, backpressure is also not desirable, but there needs to be a balance struck with velocity for pulse *timing* and an acceptable amount of backpressure. the *net* gain for power may require some back pressure to exist, to get the right velocities, but this is a side effect and not something that you aim for. backpressure being 'needed' for power is old school

normally i dont comment in these threads where i have no business, but since you seem to think your opinion is so highly valued here, i thought i would give mine to you. every single post of yours in this thread has been nothing but worthless slander or opinion, being quite a serious situation for the people involved i dont see the need for you to troll blindly. SK is a grown man and can defend himself, as he has. fwiw, theres a very large difference between paying large sums of money for contracted work, and getting your 'mate' to help you out.

although a retune isnt *necessary*, i agree with you. a more free flowing exhaust causes an increase of airflow, which gives a higher voltage on the afm for the same load and rpm, which then means your hitting different cells on the fuel maps = running richer. same thing happens on sr20's an exhaust which gives you more power up top, means that it flows better then the previous/stock exhaust. flowing more up top, means it flows better down low as well, its not selective - and with less back pressure response and power is always increased, no matter where in the rev range. the lack of zip is probably associated with the richer afr as explained above.

this was harolds idea ???

i agree your extractor piping size and length will affect your power band, but the same principles dont apply from the cat-back onwards. least restriction is whats best, and the 3" achieves that better then the 2.5". also i think your calculations are off. i couldnt follow your calculations, it seems like you have skipped inbetween steps, i couldnt make out all the variables and its been a while since i used moles in chemistry so it was a bit hard for me to follow. maybe a bit more step by step would be good.. but basicly what your saying is that @7000rpm, the velocity of gas out of the 3" pipe is going to be ~70cm/sec, that to me is way off, seems way to slow. rev your engine to 7K and see how fast the gas is travelling out the tip, certainly much faster then 70cm/sec to me... putting all that aside anyways, i dont see what those calc's prove anyways. back pressure, by definition, causes a loss of power. even in the extractors, the least amount of restriction is desirable, the only reason why you dont go for the least restriction in the extractors is for scavenging purposes. the scavenging gives a net power increase, even if its not the least restrictive setup. in the catback there is no scavenging effect so the least amount of back pressure is desirable. velocity is not desirable, its a side affect. change to a 2.5" catback and i'll guarentee you wont increase any low down power at all. also for what its worth, "sufficient" doesnt mean best

doesnt matter whether its a supercharger or a turbo.. what im saying is, that afm's measure mass of air the peak consumption of mass of air is at max power, not at max torque (unless that rpms also has max power), for any given period of time. so yes, 2 engines making 300rwkw will show the highest voltage on the afm at peak power, and since they both make 300rwkw peak neither will max or both will max.

my bad i misunderstood you

yeap your right, julian makes mention of this in the book and the manual, he says the solenoid 'hovers' between the open and close state with a high enough frequency (not necessarily a bad thing). if i had a multimeter that measured frequency i would have tried around 15hz and see how that went on my sr20 stock solenoid. yes i realise all of that and that the frequency remains the same when you change duty cycle, but your missing the point, there is[/] a reason why you would want to adjust the frequency. like i said, with too low a frequency the output stream of air is too 'choppy' (pulses of air are too big and seperated) and gives fluctuating boost, increasing the frequency within the limit of the solenoid gives a more linear stream of air that goes to the wastegate that gives a more stable boost. as for the avcr, ive never used but if thats what it displays then its one of the exceptions

power is determined by how much fuel and oxygen is burnt ie mass of fuel and mass of oxygen/air afm measures *mass* of air, so regardless of engine capacities a 2L and 3L both producing 100kw at whatever rpm, are both consuming the same mass of air.

im not sure what your trying to say cameron, whats your point ?

nope ones frequency, ones duty cycle. it can adjust both. all other ebc's only allow an adjustable duty cycle, with a set frequency - which is understandable since they come with their own solenoid and they probably found whats optimum. the jaycar ebc doesnt come with one, so you use your own, so they allow you to fine tune that - i believe the jaycar runs at 10hz out of the box, which i think is a bit low but anyways.. also the jaycar shows the ACTUAL duty cycle you are running, where as most other ebc's have their own numbering system representing the actual duty cycle. edit: fyi, as an example a solenoid running at 10hz means it opens and closes 10 times a second, so at 50% duty cycle it opens 5 times a second. too low a frequency can cause fluctuating boost when you reach max boost (which is the problem i had).

i used one of these. if your looking for something with every variable adjustable, then this is it. PROS: -can adjust the solenoids operational frequency, no other boost controller i know of allows this -can adjust 'gain' through the whole rev range (through adjustable duty cycle of solenoid), not just for the boost build up/spool area like all jap controllers do, this allows for example, a higher boost setting for the midrange then the top end, which i find very good.. again i dont know of any other controller which allows this -cheap compared to most other ebc's -held boost really well when setup properly\ -has 2 complete MAPS for the boost curve, which you choose between with a simple switch. its possible to hook this switch up to give different boost maps for different gears, say map 'low' for gear 1 and 2, and map 'high' for all others etc. CONS: -it takes time, patience, and a bit of thinking to get it setup properly, quite tedious -have to build, although debateable as to whether this is a downside -not as flash looking as ready built jap ebc's -lacks a feedback system, so spiking did occur on higher gears, although a change of solenoid frequency could have fixed this, but i never got around to trying it.

they may flow different amounts throughout the rev range, but if peak power is the same and if it doesnt max out on one, it wont on the other either.

are you serious ?!

very nice increase, quick question though how come the blue torque line ends earlier then the red. are the graphs overlaid correctly ?

ive never seen a fake WITH the red greddy sticker, how much you pay for it maybe you should ask this question instead, is the person who 'advised' you it was fake, trustworthy ? knowledge wise, idiocy wise, bangwagon wise etc..