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Duration/Lift : Power Guideline on RB26.

25K views 26 replies 11 participants last post by  R32 Combat 
#1 · (Edited)
I was wondering if anyone had the knowledge to comment on a general guideline to power limit on an RB26 (stock displacement) with varying Camshafts with different Durations and Lift?

Starting with;

Stock Camshafts - Max Power Expectancy ?

And then varying levels of Aftermarket Larger Camshaft;

252deg/9.15mm Lift (Tomei)- ?hp
252/10.05 (Mine's) - hp?
256/8.7mm (HKS)
256/9.1mm (Trust) - hp?
256/9.25mm (Tomei) - ?hp
260/9.15mm (Tomei Poncam) - ?hp
260/10.25mm (Tomei) - hp?
260/10.8mm (Tomei) - hp?
264/8.7mm (HKS)
264/9.1mm (Trust) - hp?
264/9.7mm (JUN)
264/10.0mm (HKS)
270/10.25mm (Tomei) - hp?
272/8.7mm (HKS)
272/9.7mm (JUN)
272/10.2mm (HKS)
272/10.5mm (JUN)
272/11.35mm (JUN)
280/10.2mm (HKS)
280/10.25mm (Tomei) - hp?
280/10.3mm (HKS)
280/10.7mm (HKS)
280/10.8mm (JUN)
280/11.35mm (JUN)
280/11.5mm (Tomei) - hp?
288/10.7mm (HKS)
288/11.0mm (HKS)
288/11.35mm (HKS)
290/11.5mm (Tomei) - hp?
296/11.1mm (HKS)
296/11.3mm (HKS)
304/11.4mm (HKS)
304/11.6mm (HKS)
312/11.6mm (HKS)


Maybe if you have any of these camshafts fitted, would you be able to post what power (flywheel or wheels, please state) your engine produced.

Also, at what level (in terms of lift)

Are head modification needed to fit camshaft?
Are Uprated Valve Springs needed?
Are Uprated Lifters needed?
Are Uprated Retainers needed?

Which Cam for;?
Street Tunes on Stock Turbos with Upp'd Boost
HKS GT-SS or 2510
HKS 2530 or similar on 1.5bar
or larger?


I need to start looking at what camshaft will fit my needs and wanted to do some homework but also compile the information in one place for others to refer to.

I want 550-500 whp with HKS 2530's at max boost on stock displacement (with all other modification to support), I want to circuit race the car but also drag race it (would like low 11's).

The 260/9.15mm Poncam seems like a nice popular camshaft, however am concerned with 9.15mm lift I will not hit my target hp. ???
 
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Discussion starter · #2 ·
>9.15mm Lift = Head Modification.
??? True?
Modification as in grinding of "bucket" area? Can anyone go into more detail?
 
Discussion starter · #5 ·
As far as I know. as long as the titanium grade of material is high (or durable) enough, titanium retainers from the aftermarket manufacturers will work level and for sustained period of time, where the concern was the wear rate.?

R32combat, cheers for informing about the economy/mpg relation to overlap/duration, I wasn't aware it was so related/proportional.

Stock Camshafts then are 240deg/8.25mm lift?


Do RB Motors respond in the same way as a general increase in output across the range with " greater lift as possible : shorter duration as possible " ? is that a good general rule of thumb?


Will HKS 2530's run out of steam before a 9.15mm lift cam will raise efficiency issues? In other words, would the money be wasted on modifying the head for c.10.5mm lift with this turbo setup?

It's a big difference (in terms of cost and time) between slapping in a set of Poncam's (260-9.15) and going to 10.Xmm lift Pro Cams + Headwork + Springs + Lifters + Retainers.

I'd hate to get the car on a dyno for mapping .. everything else being engineered enough (the turbo's, the fuel, the correct egt) ....with the wrong choice of camshaft and not hitting the 500whp goal I'd love.
 
Discussion starter · #9 ·
Q. When running camshafts with more than 9.15mm lift,.. physical modification is only needed to the lifter buckets? (Material grinded away from the top of the bucket? the bottom of the bucket? where? please can someone explain?)

R32Combat, what did you have to do (physical modification and parts replacement) to fit 272 / 10.5mm camshafts into your cylinder head with stock valve springs please mate?


PS. I'm not going to do the camshaft fitting myself, I will send to RBMotorsport. I just want to research what is done at each level and why to fit larger cams into the RB26 Head.
 
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