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I wanna to prepare a new head for my RB30 and start looking for new cams.
my RB30 will be boosted by EFR8374 EWG which i own already. I will be using wet sump setup so not going to rev it too high, not even planing to rev it as high as my RB26 was seeing.
As for other mods, if that matter to make advice - stock crank, nitto rods, wiseco pistons, fully preped head wit realy big porting and +1 valves, on new head we are going to work even more on valve seats to make them even more perfect and allow more air flow.
I'm gonna use car most like in circuit racing so i'm looking in ti moderate cams of 272 advertised duration or close.
Wanna get the opinion of those who has experience
My options are:
1. Tomei cams as i'm a dealer and got a very good disocunt on them
Downside of Tomei cams is that i need to buy valve lifters whith them
2. Jun cams - i got a set of jun cams now and they are performing realy well, a set of 264in/272ex with lof lift allowed me to get something like 500whp at a boost level of 1.3 bar only with a 2.6l RB26.
Jun cams are more expensive and as far as i figured out jun also use smaller base circle and they offer they own retainers to compensate these
3. HKS - HKS is know as a good expert in valvetrain and they offer 2 variants
272 with low lift of 8.7 ony - which uses stock base circle and 272 with 10.2 lift which is 1mm lower base circle and they do not offer solution on how to compensate these. I guess special retainers will do good here like Jun.
4 Kelford - the are know as the best manufacturer of cams. They offr some variants that suits me:
182-C Camshaft Set 272/272 Degrees advertised duration, 10.00mm/9.95mm lift.
L182-B Camshaft Set 272/272 Degrees advertised duration, 8.95mm/8.90mm lift.
And most radical i assume usable for me
182-S Camshaft Set 274&270/274 Degrees advertised duration, 10.55mm&10.50mm/10.50mm lift.
Kelford does not gives any information on base radius
So my question what would be your advice on what cams to select and why?
I try to pay most attention to intake/exhaust valve events when selecting cams. As a general rule in selecting a cam for boosted applications the valve overlap is important which is greatly affected by Lobe Separation Angle (LSA). While a small amount of overlap may help maximize cylinder fill too much can decrease performance. You don't need your boost blowing strait out your tail pipe! Exhaust valve duration is more important than intake duration in boosted applications. The intake will be assisted by the boost but your exhaust needs to have sufficient time to let the burnt fuel/air out. If its not open long enough to get the spent charge out then too much burnt air could remain in the cylinder preventing you from getting a full fresh f/a charge back in. If you know Intake/Exhaust Duration, LSA, and Ground in Advance (GIA) you can mathematically calculate valve events. A good cam manufacturer can usually help in choosing the best possible cam and many will custom grind to meet your exact setup at or only slightly more than the off the shelf "boxed" price.
Cam selection is probably the most important part of engine building as it will ultimately decide where in the RPM range you can make torque.
I've heard people say HP is for bragging but torque wins races!
Hope this helps.
Thx a lot for your opinion.
Yeah i've noticed exhaust is vital as my RB26 engine originally come from japan with 264in and 272ex, and it performed realy great.
You mentioned you're a Tomei dealer. My experience with a lot of Japanese products like this (such as HKS or Apex'i) is that the support is very limited. If you have a quality problem or a question, it takes a long time to get a returned product. The people who actually know anything about the product are in Japan and they don't speak or write English very well plus they are really hard to get ahold of. So unless you are really happy with Tomei, I recommend you go with Kelford because they are in NZ.
I'm happy with tomei yet. But i dont like the idea of changing my valve lifters together with cams, but atleast it is stated there. Kelford does not gives any information on that.
But i read a lot of good reviews on Kelford, adn Robbie Ward of RIPS racing also recommend them. Here i hope to hear some more detailed information on what to take in account when choosing cams