jarrod83

0.4 isnt too bad, i think the new cars are down under the 0.3s, but the old cars were closer to 1, i think i remember watching on top gear they claimed the veyron required 250hp to get to 150mph and an extra 750hp to get the extra 100mph, id say you would be surprised how much power is required to overcome wind resistance at 130mph

Also rolls there power curves are usually pretty different, Im not sure about the supercharged v8s, but when i was comparing the NA V8 torque/power curves to my rb30, i noticed that the v8s power curves usually have pretty flat torque curves that result in the peak power being made almost at their peak RPM, while my car had a lot less torque off boost, but once on boost picked up a lot of torque through the mid-range and started dropping off a fair way before redline, so although they made the same peak power, my car had more torque in the top end, as its power curve had a rounded top earlier in the rev range while the NA v8 had a straight line power curve. If the supercharged dyno curves are similar could explain it.. tho im stikking a v8 in a r32, so i suppose we'll see what sort of top end speed it will get with a car thats light and has a descent drag coefficient. Anyone got a gt3788r dyno curve yet?? I've been following this thread waiting for someone to post one, so i can compare the response to my gt35r Jarrod

why not poncams and vct?

i never got to make much power, i had the worse luck on the dyno, my car would run fine for months but play up on the dyno. I made 420 hp on 16 psi low timing, moved it up to 21psi and it made 440hp at 4900 rpm with still low timing, but the run had to be cut short because the car started leaning out, that run looked like it was heading towards 460-470 easily without any timing added, we thought it should make 500hp easy and the tuner sent me home to work out the fuel issue, which after alot of head scratching i found that the alternator nut had worked itself loose. After that i had some bad luck and broke my oil pump on the limiter, so im currently rebuilding trying to get everything right for the next attempt, my goals 400rwkw with all the extra money spent now, as well as the added poncams and methanol injection, which hopefully is enough hp for quarter mile time i want to run. Only question mark left in the car is this cheap intercooler kit i bought on ebay for like 270$ when i first got the car Anyone know if these 100mm core coolers will swap directly with a 76mm 3"inlet n outlet styled intercooler? Jarrod

you could always get the 100mm cooler for extra flow.. and spend the 800$ left over on a water methanol injection kit, which will most likely help you alot more than any intercooler upgrade.

what turbo and boost were you running to make 465rwkw? jap_muscle, have you by any chance measured the pressure drop across the intercooler?? just curious as i have pretty much exactly the same setup, and im trying to squeeze every last hp i can out of the gt35r, been contemplating the upgrade to a 100mm cooler for a while Jarrod

anyone know where you can get a normal extended cover? mines got this poxy bit of metal i hammered and riveted together

what coilpacks are you running?

do you still have the 4" intake pipe, air filter and heat shield? would you seperate them from the turbo? Kind Regards Jarrod

It does sound like it would be a mean setup.. but a big turbo is always going to feel like a big turbo and not a responsive v8 I have a rb30 with a gt35r and its pretty damn responsive, but it really cant compete with v8 torque anything under 3200 rpm even tho its making 12psi of boost there, it just doesnt make the torque/hp until the turbo really gets going at 3500+... theres also that slight delay before you come onto boost when you put your foot down even when your high up in the rpm. Jarrod

map sensor for the win, the afm pissed me off to no end. the volume will decrease proportionally provided the temperature doesnt increase, but yeh generally the air is alot denser on the intercooler side, so it makes sense that the inlet side would need a bigger sized pipe to flow the same amount of air, also considering the pressure differential is probably alot smaller on the intake side as well. Always sounds good in theory but probably only makes a bees dick of difference, although it makes it easier to run a larger air filter which probably helps as well.

it looks like a rb20 head to me in every way, as far as im aware the rb20s dont flow as much air due to the smaller valves.. without knowing exactly whats been done its hard to speculate what sort of power its capable of, but i guess 400-450hp may be more realistic than 650hp.. i would stick on a gt30r n see how it goes

Hey im in perth, can i come and check it out? keen to buy it today 0406029037 Jarrod

the threaded end in the rb30 block is for a oil filter to screw onto, you have to remove that from the block and replace it with the piece from an rb25 block that fits into the back of the oil cooler... Jarrod

That was an awesome explanation of the problem.. its funny how he summed up so many points me n rolls covered.. with the whole cvt etc, and this bit "Hmmm... P = F * V ...rearrange to get F = P / V ... that means that you get the maximum force pushing the car if you maximize your *Power* at any given velocity. This gives us another useful rule: Shift to maximize engine POWER, not engine torque!" funnily enough i had to use all these formulas for my exam today, except i had to calculate the maximum power i could get a car to produce at 80kmph and the equivalent engine rpm with different gears and the diff, subtract the drag power loses, then calculate the maximum hill gradient the 1800kg car could cruise up, P=mg sin(hill angle) * velocity ftw

Ben i think they are just saying although you were probably trying to help.. it just wasnt a very helpful suggestion, simply because even if you had a bent throttle body it wouldnt give his symptoms, if it was bent so it was leaking in air at idle it would be idling higher than usual, if it was stuck in a position you would know and if it was opening up but bent.. it would not stop your car from making boost, i would imagine that even if it was bent so it was half covering the hole, it would still easily make 7psi of boost... simple because those turbos begin to make boost as soon as the throttle body starts to crack open

stupid explorer

if your going to be pulling off the exhaust bolts to have a look, just make sure you hit them up with some wd40 a few times the days before, by the time i pulled mine off they felt lose, while my mechanic friend broke 4 of his studs off the head. maybe the best solution would be to see where that swoosh noise is coming from before you start pulling things apart, if its on the exhaust side you can usually feel around and find any leaks while the engines cold once you start it up, although i would expect to hear any leak big enough to stop boost.

the speeds in mph, liking the 900Nm of torque by 2500

maybe you's are thinking about it the wrong way?? we have clearly proven that if you gear down the maximum power to match the speed of the maximum torque, that the maximum power will have more torque?? correct?. If you look at the torque that occurs at the maximum torque though, no matter how you gear it, you can not gear it so that the maximum torque will have more torque than the torque of the maximum power at the maximum powers speed!? simple enough.. so it stands to reason that at the speed or rpm's that the maximum power occurs.. that the car will be geared to accelerate at its maximum FOR THAT SPEED. so the more time you can get your car to stay accelerating around the maximum power, or through the maximum average power range, the highest average acceleration it will have. No matter what you do, youll never be able to out accelerate the maximum power with maximum torque through the maximum powers power range. the same can be said for all 5 gears that when your passing through the rev range of the maximum power, your car will be accelerating at the maximum possible rate FOR THAT SPEED.. for all 5 gears now it can be clearly seen that power is very important at accelerating a car verse its speed.. if your car can have the maximum average power through the range of speeds you spend the most time in, then your car will be accelerating at the maximum average rate it can be.. the only gear where maximum torque plays a significant role over the maximum average power is the first gear. from this its simple enough to see that yes, your car will accelerate faster where you have your peak torque for that gear... but your car will accelerate on average, faster when the rev range it spends the most time in has the maximum average power... this is why cars that have nice big fat power curves are generally alot quicker than cars that have narrow power bands or lots of torque early and not enough in the top end resulting in bad average power or lots of torque too late giving a very narrow power band and not very much usable average power. You can tune for peak torque or maximum average torque, but without looking at the power curve or estimating average power of the torque curve you have no way of knowing how well it will perform to looking at the area under the power curve. now if you had a average car and tuned it two ways... first way sacrificing maximum and average power for a higher peak torque.. then sacrificing the peak torque for a higher average power and compared the accelerations to their top speed or even the first 4 gears. If you compared the acceleration versus time, you would see that the maximum torque car would have higher acceleration peaks but spends considerably more time with a lower acceleration, which verse time isnt very effecient. If you looked at the maximum average power car, it wouldnt have the same peaks, but it would spend alot more of the time with a higher acceleration especially in the higher revs where the car spends alot more of the time, its acceleration curve would be alot more effecient with alot more area under the curve. If you add to the fact that when your trying to get the maximum power to the ground.. its better to have less peak torque and more average power so you dont spin the tyres as easy now honestly i cant make it any easier than that... if you dont understand it, then you simply dont understand physics.. if you really want to argue though.. prove the car can out accelerate the speed it has at its peak power at with its peak torque.. or better yet.. work = power x time.. if the car is doing more work at the higher power range, work goes towards kinetic energy, over coming friction and over coming drag.. which both cars have to do.. where is the extra work that the higher powered car is producing going towards.. if its not going towards increasing its kinetic energy? which causes it to accelerate faster than the lower powered car. Plus once you understand power as a rate of work, youll understand that just quoting torque(work) is useless, it would be like me saying look i need you to lift these 40 boxes onto that shelf.. which is the amount of work... your thinking, yeh i can do that.. then i say do it in 1 second.. which is the rate of work, 40boxes/sec.. can you still do it? In the same manner quoting work(torque) without the time its done in or the rpm is meaningless, once you add either time or the rpm..then you have the rate of work.. i.e power!!!! Last of all, if you actually sat down with the two torque curves, one with higher torque, one with more average power... you have the torque for every rpm range in 4th gear, you can then work out the torque for the other 4 gears, with the diff ratio you can determine the torque at the wheels, from the torque at the wheels you can compare wheres the best place to change the gear for both examples. Once you have narrowed down when you are changing the gears you have the torque versus speed from 0 to 260 or so, from there you can calculate the force the tyres are applying on the ground based on the tyre size. With the mass of the car you can determine the accleration for each force versus speed. you can then use numerical intergration to determine the required timed to get between each speed with the accelerations between the two points. you now sum the times and have the time taken to get to each speed... determine how far the car goes with the time between each point.. you now have torque vs speed vs distance vs time vs acceleration...

no worries r33 racer, i was about to send my block off without my ARP main and head studs, maybe i should add them in. Overall the build up went pretty well first time around, when i first started the rebuild i had like 3k and was planning just a standard rebuild, bore ended up being rusted and stretched the budget as much as i could to include forged internals, arp steds, ceramic coating etc.. probably should of payed a little extra and gone to a better machine shop and a new oil pump. The ring gaps ended up being huge.. they were considerably larger than the 21thou i had calculated, i was 2 weeks past the end of my holidays and decided to through it together anyway, decided to run the internal vct feed and left the oil restrictors unrestricted, had tonnes of oil going to the head and had the vct doing some weird clicking.. so going to go to an external vct, run oil restrictors and replace the solonoid this time. Engine was running sweet for a while, had a few teething problems on the dyno and never made over 450rwhp due to it leaning out with a melted alternator bolt first time around, went to a different place second time and melted all the wires around the dump pipe.. boy do they get alot hotter once everything is ceramic coated but the dump pipe, plus it doesnt help that my wastegate runs between the dump pipe and the body of the car. Ended up discovering that the timing belt was out half a tooth, so considering that my 450rwhp effort wasnt half bad considering it stopped early and look like it would of easily made 470+ on 21psi with low timing. the goal was 500rwhp, should make it. had a few problems with the harmonic balancer and the keyway, whether the bolt wasnt done up enough or the keyway was flogged out, it ended up getting weird pitting all on the inside of the balancer, had to replace it along with a new keyway. A few burnouts later i was going up a hill one night, clutched second and bounced to the limiter and got a strange knock reading, after that, whenever it hit high boost it would knock and occasional when you were driving around town at low speed it felt like was hitting a brick wall for a split second.. swapped the ecu and afm for a haltech ecu n map sensor and it seemed to fix the problem, sent the car to get re-dyno'd and the oil pump shat itself. Pretty sure i broke the pump on the limiter and it was bouncing around still working for abit before it completely let go, possibly caused by the problems i had with the harmonic balancer.. though im sure the limiter bashing in the burnouts didnt help whilst i was pulling the engine apart to replace the bearings and pump.. i found ceramic spark plug insulators in the exhaust, most sickening feeling.. anxiously pulled the head off only to discover the spark plugs had all came apart and trashed the engine. The spark plugs are a bit of a long story, in short i changed my usual plugs from bcpr7es to the equivalent v-notched ones, picked them up a day later to find out they were 5s and that the 5s were infact a colder plug than the 7s, took the car to the tuner with the 5s in and questioned, inwhich he agreed that the 5s were no good so we went back to my original 7s, i said they were a little bit fouled up and that i would give them a quick clean and pop them in, in which he claimed he could just give them a quick clean up by quickly burning the oil of with a oxy, bringing them up as good as new. So rebuilding, hoping to get all the little things right this time, starting with a new block/crank, sending it away to get machined this time, getting a proper oil pump, harmonic balancer, oil cooler, cams, springs etc.. hoping to crack the 400rwkw mark with some help from the water methanol injection. hoping this time to spend alot more time doing away with lines and wires i dont need and simplifying the engine bay as much as possible and fixing all the little things that i wasnt happy with last time Spewing i have to wait so long to have a play with my new haltech ecu and WMI

when i said power causes torque i meant the power at the engine, will determine the torque and the angular velocity at the wheels, so when comparing an acceleration at a speed you would compare the possible gears you could be in for that speed. Im pretty sure you are right about the torque causing power because if you applied a torque to a bolt and it didnt move, then youve applied a torque.. but no work or power has been done, power wouldn't exist without the torque. Though you are wrong about the power and work relationship, as work can be calculated quite a few ways. Power 1W= 1J/s=work/sec or Power x sec = Work Watt=work/sec=1kg.m^2/s^3 work =1J=1kg.m^2/s^2 Work =power(watt)*time(time)=1kg.m^2/s^3*s= 1kg.m^2/s^2 work=1J=1N.m=torque... work = torque.. rate of work = power.. 1N=force=Mass x acceleration 1kg.m/s^2 work=force x distance=Fd Work=Fd=m*a*d=maV/t=FV/t etc etc there are alot of variables in determining whats best at the end of the day, maybe they dont like to rev there engines that much? maybe the gearbox loses with the extra torque and revvs add a considerable amount to the drivetrain loses, extra torque places extra tangential forces on the gears, especially considering the lower gears have a higher reduction ratio, requiring a smaller pinion to fit in the same sized box.. F=T/r=more force+ more friction due to higher revs.. and it doesnt pay to rev the engine out as long as you would if you were assuming there are no drive train loses.

and i forgot to mention that obviously the torque for the given power causes acceleration.. but as i clearly pointed out, what determines the torque? the power. dynos may calculate their power from torque.. but power is still the measure the amount of work being done.. the work is what adds to the kinetic energy causing an increase in speed and overcomes the forces of drag and friction. Therefore to compare the peak torque a engine produces at 2000 rpm in 4th at 60 kmph to the lower torque it produces a 5000 rpm at 142 kmph, without taking into consideration the work the engine is actually producing and the increase of wheel speed. It kind of similar to how everyone compares the speed/cost of a bike and a car without taking into consideration how much more a car weighs. If you dropped the wheel speed of the engine at 5000 rpm down to 60kmph instead of 142kmph then it will have a proportional increase in torque, so for a given amount of work a lot more torque would be produced. Similarly, if you dropped the weight of the car to the bikes weight, for a given amount of work, it would produce a lot more acceleration.

yes but torque is meaningless without rpm.. to make the same wheel torque at 100 times the wheel speed is impossible... its simply not the way the world works.. combustion engines make it alot harder to understand the power/torque relationship, if you consider an electric engine with a fixed power applying work to an input shaft. They apply a fixed power, therefore a fix amount of work to the input shaft, yes the motor will be working also at a fixed torque and rpm. But the amount of work it can do is determined by the power the motor is making. The motor then runs through a gearbox, the amount of torque it can supply to the output shaft is directly related to the gear ratio and speed of the output shaft. The faster the output shaft has to rotate, the less torque it can apply to the shaft due to the increased velocity ratio. Although the motor is now outputting less torque.. it is still producing the same output power and work neglecting energy losses. P=TxRPM from the peak power you can output any torque and any rpm.. but not without proportionally effecting the other, this is simply because the electric engine can only produce so much work, even if you had multiple gears as soon as you gear up to increase the wheel speed you are doing so by sacrificing torque. Combustion engines are exactly the same except there power is a variable with engine rpm.. however the total amount of work the car can do that goes directly towards accelerating the car occurs while the power is the highest, at this power range you can output any torque/rpm.. in the case of a 5 speed gearbox you have fixed gear ratios... whatever way you look at it its easy to see that the torque output to the wheels is directly related to rpm of the wheels, the amount of torque for the given wheel rpm to determined by the amount of power the engine makes at the current engine rpm. Its also very easy to see since Work = Power x time, that more work is applied to the car while the power is at its highest... its also the reason why the highest average power will give you the fastest average acceleration. Comparing torque at a fix gear ratio over a range of rpms is meaningless without taking into consideration the amount of work that torque is doing to the car.. ie the power at that point.

so power has nothing to do with acceleration? P=wheel Torque x wheel angular velocity Torque = F/r, angular velocity = rads/sec, wheel velocity = angular velocity x radius of wheel P=F/r x angular velocity P=F x wheel velocity F = ma P=ma x wheel velocity wellah rate of acceleration for a car, that has a variable gearbox, so power and rate of acceleration is very closely related to velocity. Please find me the acceleration rate with respect to wheel speed from the torque alone. You can find the acceleration due to torque at the known measured dyno torque, but each torque point is only accurate for the fixed engine rpm and fix wheel speed, although the same can be argued for the power curve with a fixed gearbox but the maximum acceleration using the maximum power and velocity will be higher for a given speed than the maximum acceleration using the torque curve for that speed, therefore a gear ratio exists for that speed.. that a higher wheel torque is possible with the correct gear ratio for the maximum power than any possible peak torque/gear ratio... although cars dont have variable gearboxes they do have multiple gears.