rev210

HKS do enough to make the turbos work better than garrett's off the shelf. In some the case of the -5's it's a few mm or fractions on the inducer /exeducer and trim, basically a different wheel made just for them. They also have their own housings at least on the compressor side and sometimes as we know the exhaust housing too.

-5's and 2530's are different enough to make the 2530's perform far better infact on average the GT-SS perform better than the -5's. -7's aren't the same as GT-SS either. I had a quick look over some of the results (about 10 to 12 of each type except for the GT-SS , they seem to only just start to be flavour of the month) and did some totals of cars that are similar, standard capacity rb26's on pump fuel. I didn't include some of the hardcore 2530 setups like dirtgarage's to make it a little easy on the -5's. The average for the 2530's is; 388rwkw The average for the GT-SS is; 335.4 rwkw The average power made by the -5's is; 313rwkw Of the same data the best power of the -5's was 388rwkw Best of the 2530's was ; 451rwkw (have an examples of a few a fair whack higher again but, left those out). Best of the GT-SS was 364rwkw going purely of budget un-opened/ non-built motors maybe with just some drop in cams it looks like this; -5's average ; 298rwkw 2530's average ; 358rwkw GT-SS average ; 332rwkw -5's aren't bad but, then again they aren't HKS either.

bump

they are cheap certainly. Have more power than stock. But, aren't as good as Trust/HKS/Garrett/Apexi units by virtue of thier lack of power curve. Certainly not horrible for a cheap upgrade. As long as you don't expect them to go as well as a more expensive HKS unit , I'm sure you won't be greatly let down. If it were me I wouldn't personally buy one as the turbo is a major factor in determining the characteristics of performance and so I don't believe skimping is the best idea. Just my opinion.

big fat waste of time. Unless you are bored.

Could be a few things but, most will give other symptoms. A loss of compression will slice power off, to some degree this can happen without appearing a massive smoke fest. Worth a quick compression and leak down test just to check overall engine health. A range of possibillities there. The cam timing can possibly be at fault if the belt is stretched. If the belt has been changed but, not the idler and tensioner then this is possible. The shift in cam timing can cause a dip. Small intake leaks. Check the pipes and clamps. Intake pipe sucking closed. $5 fix for that one.

bump

your idler bearing could be on the way out. Often these aren't changed when people diy thier cam belts at 100k.

Not emo' just sarcastic. Don't take it the wrong way... I'm putting in my 2c of actual experience with these motors, limited as it is. I have plenty of evidence to substanciate what I am reccomending for this type of engine. I am trying to be helpfull not argumentative....ok so maybe I'm being a bit mean on the odd occasion From my actual experience Response and flexibillty are vastly improved over stock cams. If by response you mean how quickly boost comes on and by flexibillity you mean the width of the power band or average power. The stock cams aren't optimised for either else they would lose out in emissions and to some extent fuel efficiency. If we look at the profiles they have they are really conservative. Driving a nice set of well sorted Tomei drop in's is chalk and cheeze, the car pulls like a freight train unlike the stock cams. I have a graph or two of dynos that demonstrate this that have been stuck up before and if you search you can find a number of other examples of what I am talking about. You have a nice GTR I see and if you haven't considered cams before I'd be happy to show you some results specific to the RB26's. You will also be pleased to hear I have no engineering background so any time you like you can dismiss what I say, I won't be offended.

Robbo's was 12.18 with the 2535. So thats pretty much all you need ......and a 1.9 60ft or better.

Good to see you had a go at the advancing of the exhaust cam, at least in the interest of science we have some data to help others out with the install of a similar setup. I regret not taking more notes with the cams I have done in the past, especially as I am going to be dropping in some more to the GTR I have now.

Motec system YO! Yep they are fully sick. They wind lag out of motors and wind up clocks too. Strange really as I had mistakenly thought that an aftermarket ecu's abillity to add more timing brought boost on earlier and that I thought (also mistakenly) this also had the effect of advancing the intake cam timing therfore increasing the cranking compression..... You seem to be the expert mate. I've just tuned and help tune a few cam setups in RB's that seem to be at odds with your extensive and superior knowledge. I'll leave it to you to explain it all on this thread from here on as clearly I'm wrong. People who would like to hear the rantings of a crazy fool like me on putting cams in an RB can PM me but, remember there is far better info in this thread.

2530/35 should get you there.

You assume the standard cams are designed for a wide power band only? Are they optimal for the motor for power? What about lift? What about the reduction in airflow restriction in the valve opening moment? Re-think the possibillity of a better designed cam than stock. The only way to make a semi-accurate guess is to plug the data into a cam design program. I can assure you an off the shelf 256 duration set will lay smack down on stock cams even on a stock turbo. It will bring the turbo on boost sooner and make more average power. I've had the benifit or having someone run some cam ideas for an RB in the past on a cam program and it accurately predicted a result. The motor was an Rb25 with a stock turbo, it made more down low and everywhere. I have also demonstrated a 40rwhp gain at as little as 3,000rpm on a standard gtr setup with rather big 260's. Size the cam right and you get excellent results. On RB's the stock cams are ok but, far from great power wise.

The benifits of well matched aftermarket cams and aftermarket ecu are ; For an old motor: * Make the same power with : less boost / less timing / less aggressive fuel map / less rpm For a motor aimed at better performance: * More power through the entire rpm of the power band * Extended length of power band, earlier power and power into higher rpm. You can gain lots out of mild cams on an RB, particularly for a street/response motor. Any suggestion that they are a waste of money on an RB comes from a lack of experience. Even on a stocker motor ,you may have stock turbo imposed limits to the 'peak' power number but, the bottom end and mid range gains from cams make the motor night and day different if setup correctly. In most cases 20rwhp or more can be had on all the RB series, through the whole power band. Cams are very good in terms of an upgrade when done right end of story.

Thats a great gain there.

bump

only of any use when car is stationary for heat soak. Use a water spray instead.

No worries dude. Best of luck with the tune

spend a little time making some foam air guides (or a nice metal guide if you have the skills with the material) for between the intercooler and radiator so the air doesn't 'spill' making the standard fan setup work more efficiently.

oh and be prepared to advance the exhaust cam, it's not always retarding that works best.

yep. set exhaust at 0. The muck around you have is really with the ignition timing for each setting of the intake cam. I think this is related to the compression changes the intake cam effects. You want more timing to bring the turbo action in earlier but, it's striking the balance between what you are safely able to run at different cam positions. It's a good idea to really focus the tune on the 'bottom end/mid' and even go as far as to say to the tuner you don't give a rats behind about the top end, even if it decides to take a big drop. Fix that later, it's pretty easy to do. You need to make it crystal clear as most of the guys who walk in are chasing a bigger number. These are the guys I find make up the back of the field on race days.

My tip is to tune for the 3000 - 5500 rpm range first and disregard any power drop off up top initially. Most people seem to go and tune cams and shoot right away for top end and work down. The first cam to play with is the intake cam. The advancing of the cam timing increases the cranking compression, this increase is the reason (part of) why you can gain more mid range/earlier boost response. Really try to nail the turbo's full boost rpm. the basics I work off; * Advancing the intake cam moves the valve closer to the piston (be careful- not too far) and as a result you get increased cranking compression. You end up with better bottom end power. The peak magnitude of power changes is centred around really the peak of the hill (one spot) but, kind of moves the whole hill under it. You advance and generally the power peak moves down the rpm range, to a point. I think you find due to the relation to cranking compression , things like turbos airflow/boost characteristics make it slightly more tricky and effect which way you go from 0 -or+ and how far. * Retarding the exhaust cam moves the valve closer to the piston (be careful not too far) it tends to effect power more generally over the entire curve. But to less magnitude than the intake changes do. The exhaust cam setting is more of a mystery to me (someone may be clever enough to help here) sometimes advanced sometimes retard. * Tune at an initial boost a little lower than you want to end up at. Tune for increased boost later. * Dial in and advance/ retard intake cam first , then the exhaust cam. * I think the idea with the bigger cams , is 'not' to assume they need more overlap like the stockers 2+adv and -4/-6 exh, they have bigger overlap out of the box anyway. Thats why I think the stock cams need help and they are too small. being designed with some sort of emissions in mind compromises them in this way.

Have a look at the new GTR's turbos here; http://2009gtr.blogspot.com/2008/02/r35-gt...-know-your.html

I wouldn't buy it myself. It sounds like a pile of crap. It's far from a 'good clean skyline'. Unless the check on the car is free, don't waste your money. Look elsewhere.