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Discussion Starter #1
I was wondering if some of you might shed some light on this for me and share some of your experiences with your camshaft choices in your RB26 builds and WHY you made those choices.

What are the Advantages/Disadvantages/Pros/Cons of running:

1) BIG Lift/Short Duration Camshafts.
vs....
2) Low Lift/LONG Duration Camshafts.

I am having a difficult time wrapping my mind around the 'Powerband' of each, as both Lift and Duration affect low speed/high speed (RPM) performance.

Theoretically, a Turbo'd Motor likes Duration much more than it likes big lift, but take for instance, the 'Mines' way of tuning (Big Lift/Shorter Duration) and explain their exception to the 'rule of thumb'.

I, myself, chose to go with Tomei ProCams 10.25mm Lift/270 Duration because I saw that choice as a logical STEP-UP from basic Bolt-In 'Type-B' camshafts.....and NO other reason. I am now wondering if I made the right decision.

I also realize that Turbo choice plays a large part in this, but let's focus MORE on Cams and RPM/Powerband and NOT Turbo choices.

Thanks in advance,
Allan
 

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id go with low lift high duration and say these are the more torqey cam.....


high lift low duration are the high rpm cam... since at high rpm you have velocity from the turbocharged air you dont need to open them up for a long period of time...


duration is expressed in degree... each 4 stroke in a 4 stroke engine gets 360 degree of crankshaft rotation.. so for each 360 degree rotation your cam will take 270 degree for the power stroke if i got this part right.... and the 10.25mm is the lenght that the valve goes down into the cylinder.... so if you want high end rpm try to go for cams in the 270 and 280 degree bottom end torque? 260 and i even think there are some less involved cam.. but what they give in the low end rpm range they take out in the high rpm.....
 

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Discussion Starter #4
2 examples about as far away from each other down the scale as possible, to further help explain my interest....


Mine's Super Camshaft Shore Pro II. 10.05 lift, 252 Duration.
Mine's SUPER CAMSHAFT SHORE PRO II
The highest lift, shortest duration combo that I am aware of currently for an RB26.


Kelford Cams L182-C Camshafts. 8.95 lift, 282 Duration.
L182-C Camshaft
The lowest lift, longest duration combo that I am aware of currently for an RB26.


What are the benefits of each Spec/Design ?

Like I said, these are pretty extreme examples when compared to each other.

Thanks to those who are able to add something.
Allan
 

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Basically that is the most lift in an unmodified head that can be used therefore making the most of the available duration provides similar results as a higher lift lower duration design.
Jason
 

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on the subject of cams. i am re-building an engine with the following spec:-
gt2860-5 turbos
fully ported head
tomei manifolds
forged internals
etc etc.

i have tomei 270 10.5 lift cams, yet to fit.
i am concerned that with these cams i will only get the "max power" at high rpm`s.

at present i have HKS 264 cams and they seem to deliver linear power. as i am entering TA, i do not want nothing, nothing, bang, for about 2000 rpm. but more linear like now.

question is:- will the Tomei cams spoil my low down grunt, and be a bit "peaky"....

maybe i should start a new thread about this?
 

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Where they will work the best will be more a fuction of cam timing.
IMO they will be fine with appropriate centre lines to suit your application.
 

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Discussion Starter #13
2 examples about as far away from each other down the scale as possible, to further help explain my interest....


Mine's Super Camshaft Shore Pro II. 10.05 lift, 252 Duration.
Mine's SUPER CAMSHAFT SHORE PRO II
The highest lift, shortest duration combo that I am aware of currently for an RB26.


Kelford Cams L182-C Camshafts. 8.95 lift, 282 Duration.
L182-C Camshaft
The lowest lift, longest duration combo that I am aware of currently for an RB26.


What are the benefits of each Spec/Design ?

Like I said, these are pretty extreme examples when compared to each other.

Thanks to those who are able to add something.
Allan
Anyways, anyone care to comment on powerband/power delivery ?
 

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Discussion Starter #14
WOW......I really didn't expect this.

It looks as if the *cough* was the closest 'technical' response this thread has received thus far.

I am really dissapointed, as I thought that THIS Forum would be the place to ask such questions because of it's member base and length of experience with this motor/car (RB/Skyline).

Oh well, atleast everyone jumps in quick enough to show pics of their engines and wheels in most threads and something tells me that one can't expect more than that from most people I guess.

Thanks for 'sharing' all of your 'knowledge'......
Allan
 

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SP ENGINEERING TESTS HKS 264/264, 272/264 AND 272/272
CAMSHAFTS
SP Engineering

Text By: Ken Henderson and Ju-Hon Chan

THE ISSUES:
Whether or not a reverse stagger cam set-up enhances turbo spool-up, mid-range power and the ultimate power potential of the head from the Toyota 2JZ-GTE engine;

Whether or not a parallel cam set-up is inferior, or superior, to a reverse stagger cam set-up in terms of turbo spool-up, mid-range power and ultimate power production of a given engine/turbo/drive train set-up;

What are the differences, if any, in spool-up and power production when the parallel HKS 264/264 and 272/272 cam combinations are compared?


THE CAR:
Those of you familiar with our testing of 4-inch big bore exhausts for the MKIV Supra Turbo will recognize this car. Sleek, black and stock-bodied except for the carbon fiber TRD hood, it represents all that we know and love about the JZA80. Owned by Ju-Hon Chan and built by SP Engineering of the City of Industry, California, the vehicle had already under gone significant upgrades to the engine, turbos, suspension, wheels and tires and engine management prior to its latest round of improvements.

Chan decided to swap in twin Garrett DBB 3071 turbochargers in place of the previous HKS DBB GT2835Rs and install bigger cams. Since re-tuning the engine management system (EMS) would be required as a result of these changes, it was decided to conduct testing of various combinations of cams so as to provide some clarity to the ongoing discussions on SupraForums as to whether parallel or reverse stagger cam combinations work best for a given engine set-up.

Going into the testing, the critical elements of the engine’s set-up were as follows:

--A built shortblock with Crower billet steel connecting rods, forged, .040 overbore, JE pistons (with Total Seal rings) and a lightened, balanced and micro-polished OEM crankshaft;

--A ported and polished cylinder head, complete with a Ferrea valve train (stock size valves), including locks, locaters, keepers and titanium retainers and HKS 264-degree camshafts, both intake and exhaust;

--A VeilSide intake manifold, including 100 mm throttle body, surgetank, billet fuel rail and lower intake manifold;

--An HKS twins set-up kit with dual manifolds, downpipes, racing wastegates, twin Garrett 3071 DBB turbochargers and custom 100 mm SP Engineering intakes;

--SP Engineering fuel system, including dual OEM/Denso and HKS/Denso fuel pumps, 1000 cc fuel injectors, a VeilSide billet high-flow fuel rail, TRD fuel pressure regulator and related high performance fuel system components;

--A GReddy 3-row, front-mount intercooler, GReddy Evo II 4-inch exhaust system and HKS F-CON V Pro EMS, along with the HKS Knock/Amp wide-band O2 sensor and air/fuel ratio meter.


THE FACILITY:
As with Clash of the Titans (TO4R.COM) and Clash of the Titans II (http://www.supraforums.com/forum/sho....php?t=280947), testing of the various cam combinations on Chan’s car occurred at SP Engineering, located in the City of Industry, California. The company’s Dynojet chassis dyno was used for determining the results of testing the various cam combinations and Jason Reinholdt, chief engine builder, once again provided the key technical assistance necessary to bring the results of this testing to fruition.


THE TESTING:
Because Chan was so excited about the prospect of testing, he forgot to empty his fuel tank (by driving) of the 100-octane unleaded fuel it contained. The day of the testing arrived with the tank being more than half-full so the testing was conducted with the 100-unleaded which has a MON of 96. Since the 264-degree cams were already installed, it was logical to begin the testing with these cams, followed by swapping a 272-degree intake cam along with the 264-degree exhaust cam and finishing up with the parallel 272-degree cams for both the intake and exhaust. During installation, the valves were shimmed, as required, and cam timing was established with a degree wheel and dial indicator. To eliminate as many variables as possible, no tuning of individual cam set-ups took place. The idea of maximizing each cam set-up through tuning was certainly tempting, but not tempting enough to, potentially, undermine the integrity of our testing protocol and introduce additional variables over which we had no control. We believe the results of the testing to be reliable and repeatable if the same installation/timing procedures are followed by other testers. On the day of the testing, boost was limited to 1.5kg/cm^2, or 21.3psi.

--------------------------------------------------------------------------------
Last edited by braddman : 12-08-2006 at 01:49 PM.

ruup2it
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12-06-2006, 10:15 AM #2
ruup2it
HKS Twins


Join Date: Aug 2001
iTrader: (1)
Posts: 106 THE RESULTS:
Without further ado, the following dyno graphs are the results or our testing:





Dyno #039 is the baseline run with the 264/264 cam set-up right after the installation of the Garrett DBB 3071s and clutch rebuild. A safe tune with 100-octane unleaded and a boost setting of 21.3 psi was decided upon by SP Engineering for comparison and used for each cam combination tested.

Dyno #057 is the dyno graph that shows the results when the 264-degree intake cam was removed and a 272-degree intake came installed in its place.

Dyno #060 is the dyno graph that shows the results when the 264-degree exhaust cam was removed and a 272-degree exhaust cam installed in its place.

In conclusion, the dyno graphs above, essentially, mirror HKS’ own testing results as shown in the dyno graphs below taken from its website. Moreover, and the primary reason why this testing was undertaken in the first place, our results showed that reverse staggered cams, in combination with the poor flowing (relatively) exhaust ports of the 2JZ-GTE cylinder head did not show improvement to the motor’s power band. In fact, the reverse staggered cam set-up increased spool and took away from the motor’s power band at all levels, low-range, mid-range and the top end as well. Additional information on the 2JZ-GTE cylinder head can be found (TO4R.COM) in an excellent article written by JZA80 guru Lance M. Wolrab.

http://hksusa.com/images_products/1440.jpg

http://hksusa.com/images_products/1441.jpg
 

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well i talked to the kelford guys today and they said 272 low lift would be best for 500 awhp and street and track.
 

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Cheers everybody,
I'm interested in Kelford 182-S cams, Anybody here has got them? These are 270-274 degree 10.8mm lift and especially good for e85. Kiel from Kelford is recommending them for a street set up.

" If the head is coming off and you will clearance then the 182-S is my pick, the split inlet lobe is very effective in the RB head, helping spool harder and faster and also keeping the rev range still quite extended, they are very close to a (best of both world) type cam and would be my favourite for that turbo frame (PTE6466 0.84) but it does require clearancing for the higher lift. "

What do you guys think?
 
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