jarrod83

Damnit this happens every time i take so long to type my point that someone has already made it by the time i say it , good point tho.. but you can actually shift a fair but after peak power and still be making more wheel torque.. considering the great change in gear ratios from first -> second -> third, significantly reducing the torque, you can see in my excel charts that everytime my car changes gear at 6750, the torque to the wheels takes a huge swan dive

i think there probably is no correct answer for this one.. as elite said, its very dependent on the gearing, the peak torque will give you the maximum acceleration for that rpm for any gear ratio, the tricky thing with power is if you looked at the two cars acceleration over a range of speeds the car with the most power would have more acceleration at some speeds, theoretically the highest average power should give you the highest average acceleration even though it may have less peak torque. If you were to compare the torque/power curves of two cars... the car with the most acceleration at a particular speed would constantly change over the course of a quarter mile. If you look at the excel pictures i drew up it shows that although the car with more power doesnt accelerate as hard in a particular gear.. it can use the lowered ratio gear more effectively for longer before it needs to change into the next gear, which is where the power vs speed part of considering a cars acceleration comes into play. The torque curve is still an important aspect, and it would depend on your definition of a better/faster car on whether peak torque or peak/average power is faster, im sure we can all agree that early torque is more important for acceleration/response, whereas late torque is more important for top speed etc.. if you were after the fastest accelerating car say from 3500 to 7000 rpm, comparing to identical gearing setups, the car with the maximum average power through this rev range will have the fastest average accelerating car through this rev range regardless of peak torques, average torque curves or peak power, which is why i say as useful as torque is, average power is more useful..you dont need rpm references for average power quotes. Also any car with a descent peak power, aslong as its in a wide enough power range to keep a descent average power through the gears, it wouldnt matter where in the rpm range it lied the car would still be fast, whether it is 50, 1000, 7000, 200000 rpm. Can you say the same for torque? I would say that people that read torque curves interept them with respect to the rpm, they probably look for good midrange torque that hopefully stays nice and flat to the top end like PMR-33 was mentioning, that torque curve would sitll give you a very high average power. But the peak power figure would give you a better idea of the average power than the peak torque without a rpm reference. At the end of the day you can argue all you want with facts and opinions, all you really need are the laws of physics to back up your claims. If anyone can find me two torque/power curves of skylines one with more average power from 4000-7000 and one with more peak torque down early, ill be happy to determine the acceleration versus time and speed, and distance versus time, i can even include the drag forces if you want with an appropriate drag force coefficient for a sports car

Heres an interesting spin on our dilemma, if you had a variable gearbox that could hold the engine at a constant rpm while the car accelerates, the fastest acceleration would occur while the RPM’s were held at the maximum power not at the maximum torque. Also whenever you quote maximum torque with an rpm, you are indirectly quoting the power. I got bored and decided to do a torque verse speed comparison of a stock torque curve and a torque curve that’s roughly been offset forward 2500 RPM to give two torque curves of similar average area. One has more top end power, would be good to do something similar to two actual torque curves of skylines that have similar peak torques but considerably different peak powers. The final diff reduction has not been included in the torque calculation and assumed to be 1:1, except for the second car B data point, that has been changed it to a 1.3:1 ratio Although its not the most ideal comparison, it does highlight the fact that the rpm range of the peak torque can have a considerable difference to the overall average acceleration of the car due to the torque. Both curves have the same amount of average torque, but the graph that has the most average power has considerably more average torque over the range of the first few gears. I wouldn’t mind working out the acceleration of the car versus speed and the time required to reach each speed.

Hey guys, anyone able to suggest some recommended/preferred rings for a rb30 looking to make around 500rwhp at 25+psi, i was going to use CP or ACL rings, but its been suggested by my new engine builder that i may need some pretty high priced rings to seal properly with that amount of boost. The recommended rings were total seal rings.. and were quite overpriced compared to the other ones and i haven't ever heard of them before Cheers Jarrod

ok i think i know where elite is going wrong, hopefully i can better explain this without offending anyone. People often draw vast conclusions from half vast data, meaning people often assume a car has one gear and often get confused the information that a dyno sheet actually provides, from the posted website this sentence is correct. "First of all, from a driver's perspective, torque, to use the vernacular, RULES :-). Any given car, in any given gear, will accelerate at a rate that *exactly* matches its torque curve (allowing for increased air and rolling resistance as speeds climb). Another way of saying this is that a car will accelerate hardest at its torque peak in any given gear, and will not accelerate as hard below that peak, or above it. Torque is the only thing that a driver feels, and horsepower is just sort of an esoteric measurement in that context" yes the maximum torque produced at a engines rpm for that gear will produce the fastest acceleration FOR THAT GEAR, which i stated im pretty sure in my first post. But once you start comparing the rev ranges the car is in as it goes through all its gears the difference in acceleration becomes blatantly obvious, so yes in 4th when ur car has 400Nm of torque at 1500 rpm at a speed of 43 kmph, with your 1:1 drive train ratio you will have 400N.m of torque at the wheels. you will accelerate faster than my car throughout my entire 4th gear rev range assuming my car only has 350Nm of torque at 4900rpm, but while your in 4th at 43... im in 1st at 43.. hello im at 4900 RPM, so my 350Nm of torque through my first gear reduction ratio of 3.592:1 becomes 350x3.592=1257.2Nm, i now have triple the acceleration of your car.. so you decide to drop your car back to first gear and upto 4900RPM where my car has more torque than your car.. i win again. The only time your car will have more acceleration than my car is when we are taking off, and yes my car will never have more acceleration than that early burst you get in first gear.. but after my torque curve passes yours at say 3500RPM my car will have more torque to the wheels at the end of first and the remaining 4 gears.. as each time i change gear my car drops back to 4000+ rpm, so from 30-260kmph my car will have more acceleration. If you think about it logically... besides a gtr who the hell can get there power down in first gear? I know this point is exeggerated somewhat, but im just trying to display why maximum power decides the maximum "average" acceleration more than the maximum torque, too many people read a dyno and assume there car only has one gear, or dont truely understand the power torque relation, or how it changes once the variable of a gearbox is introduced. If your chasing the biggest push into the back of your seat you can possibly get.. then go after the maximum torque you can get, if your after the fastest accelerating car through the gears then you require the maximum average power between an appropriate rev range. The only time early torque is a really a factor, is for towing, where your require the early down low force for taking off

Rolls pretty much hit the nail on the head with this arguement, i think alot of people dont understand the fact that if you had a car that can rev twice as much as another car, and had the first cars torque curve stretched over its rpm, that the second car could be geared (2:1 reduction ratio) so it had twice the torque at the wheels than the first car, also note that with its new gearing.. what hasnt changed versus its rpm?? its power output. Both curves are pretty closely related and can both be used to interept a cars performance. All the people that are aiming for flat torque curves are still aiming for maximum average power, just looking at it from a different, less descriptive perspective, as the power curve displays the rate of work being done to move your car forward, ie your torque curve can start dropping off long before your power curve and long before its time to change to the next gear.

I think at the end of the day if your happy with how the car drives, then thats all that really matters. Definately tune for the most average power, you cant create more power from torque, but you can create more torque from power., ie stay in the previous gear longer where you would be producing more torque to the wheels.

I had a pretty laggy setup at first with my gt35 0.82 on my stock rb25 with 6boost manifold, plazmaman plenum, 3.5 inch exhaust.. was making full boost to about 5000 rpm, eventually i found out that the wastegate was missing its valve stem seal from when the exhaust got done, omg at the difference... these are the results recorded from my blitz i-colour 2400 rpm 0.53 bar 7.685psi 3000rpm 0.57 bar 8.265psi 3500rpm 0.96 bar 13.92psi 4000rpm 1.59bar 23.055psi 4200rpm 1.82bar 26.39psi i wouldnt call it responsive, but i would hardly call it laggy, i never got it dynod with the valve steam seal fixed but it made 408rwhp on 18psi with it broken, my forged rb30 hasnt come close to making more power yet as its only running 21psi but it manages to make the boost by 3500... quite alot of fun on the street =), i think its a good compromise between power and response when your looking at the 450-500rwhp range... havent had any problems with choke.. only an annoying afm surge issue when i get off the power... map ftw Jarrod

out of curiousity did you drill out the oil returns in your block/head as well as enlarging the 2 rear oil drain oils in the head?? one of the holes in my head is barely a hole at all, the smallest bit is at least a third the size of the narrowest point in the block. did you end up checking your crankcase pressure with your map sensor?

what sort of balancing was done on your crank/rods and pistons? ive had a similar problem on my first pump, which was only a standard rb25 pump, standard balancer etc.. and shattered the pump in a similar matter, only the outside ring was also broken into about 9 pieces, but my oil pump continued to work for a few weeks after the time i think i broke and use to lock up every now and then.. which could explain the outside ring being in so many pieces i have mainly had things suggested that youve already had done.. the harmonic balancer and billet gears, aswell as very good balancing, its hard to make out but your pump seems to have the same unusual wear mine has on the inner gear where it gets driven, as well what looks like heat marks, someone suggested to me that there may not of been enough clearance between the crank collar and the oil pump drive The last thing i have had suggested briefly that i dont understand at all, was something about checking the clearance of the block for the oil pump, i think they mean making sure that the block that the oil pump sits against is flat, but i may be wrong hopefully we can get some experts in here with alot more experience and point us down the right direction and maybe enlighten us to anything we may of missed Jarrod

any updates on how your internal vcts are going with oil restrictors in place.. vct still functioning correctly?? anyone suffering from oil in the head still? Jarrod

i think the gtst power steering pumps may pose a small problem.. different ribs on the pulley and i believe its a slightly different offset, as i had a bit of trouble fitting a gtr pump to a gtst Are the ross drift ones any good?

awesome read, im a little confused with the line that vents the air from the crankcase to the catch can.. if you weld the return onto the sump will it actually be sitting below or above the oil level? Jarrod

there is other ways to fix the note.. i had a 3.5 inch dump/cat, to a 3 inch hks exhaust that megaphoned out to 90mm just before the muffler, it sounded lovely with a 3inch dump but had a horrible drone with the 3.5 inch. replaced it with a dual 3.5" xforce muffler with a section rewelded so it was full 3.5", it is very quiet and no drone, a touch louder than a stock exhaust.. the only problem im having is because of the second oval muffler is where the resonator would usually sit, it does sit a bit closer to the ground Jarrod

do you have the standard ecu? Jarrod

no worries, jumper leads dont deliver enough current to get the car started when the battery is fairly flat, could be due to the cheap leads i have but ive always had to leave them on for a good 15 mins with the other car running to get it started... a jumper pack however fires it up first go every time Jarrod

Im a bit confused to your reference to the "correct settings", as i thought the % was just a trim to the overall base injector duty cycle.. whats wrong with increasing the %?.. when i was running 27psi i had to turn the % up a bit more than the 55%, i always thought that correction was just to get your tune in the ball park of your old injectors so it can be driven to a shop and tuned?? Im probably wrong tho Jarrod

This is not really a solution.. just a similar comparison.. when i had nismo 740ccs in my car.. even tho they were twice as big as standard.. 370/740 = 50%.. i had to set them to 55% to get my tune similar to the stock injectors and fine tuned it from there.. i never really got the idle perfect it would be rich oneday lean the next.. either a air leak or you may have to relearn the idle.. i was just too lazy.. it runned fine. ill check the injector times for you in an hour Jarrod

hard to guess with very little info.. air leaks are pretty common tho.. and can cause it to run rough and stall Jarrod

thats flat battery... either get a jump pack or a new battery... it will start Jarrod

when you try to start it, does it turn over or just make a clicking noise?

are there any good sandwhich plates with thermostats that are reasonably priced?

probably way off the mark here, but i was trying to think of something to explain it using more fuel and making less power. do the nistune ecu's still have the standard ecu's rich and retard if it knocks? Jarrod

nah not yet but im planning to buy a nitto oil pump. Was using motul 8100 5w40, measured my crank collars thickness on the flats to be 41.1mm .. and from the jigsaw puzzle of a oil pump, the gap is about 42mm on the flats where did you score the block from?? my blocks only good for 40 thou now since is has some scratches in the bores.. chasing a new crank/block if anyone knows anyone that has one.. Jarrod

Im pretty sure you can rebuild a os giken, but they havent got alot of meat on the plates.. so you would have to get it inspected to know for sure +1 for NPC... ive had one for about 8000kms, making about 450rwhp, clutch second shitloads. worth every penny.. only im kinda wishing i had gotten the sprung hub instead of the racing solid centre.. might be a little easier to drive, tho its no harder than my old brass button have it out atm and it still looks brand new.. no groves/gauges on the plates/flywheel like my brass buttons use to get.. overall the npc is a way more solid clutch and would have alot more rebuilds in it that an os giken, id more than likely break a os giken Jarrod