What Cams, and valvetrain for my application (gt2860's)

[mitch32]

Hello,

I'm rebuilding my motor and need to order some stuff for the head. I'll be running GT2860-5 with 700cc Injectors, built bottom end, hopefully with a 8500rpm redline. There alot of options I'm just not sure what is the best for what I want. The car will have about 5-10 lapping days a year and in the summer probably will be daily driven (around 5000km a year). If anyone has any advice give it, my engine and head are sitting at the machinist waiting for parts.

Thank
Mitch

[NismoS-tune]

You'd be fine with some Tomei poncam Type B or R. That's one of the better street cams for those turbos. You could go procam and get more lift and duration but sacrifice streetability a little. 264 is pretty good for those. Port match, maybe new springs, that should be ok for 500hp or less.

[mitch32]

Thanks NismoS-tune for the reply.

By new springs as in aftermarket or stock new?

When you say port match I'm guessing you mean exhaust manifold to exhaust port on head? The intake side I believe is matched from the factory, correct?

If I go with new aftermarket spring do I need new valves/retainers? There will be more pressure on the valves, thats why I'm asking.

Thanks
Mitch

[mcfly]

The exhaust ports can be improved vastly as in stock form they are only 6x% efficient. Just use caution if you port them as their are a couple water galleries. If you look at this picture set you can see what I mean.

http://www.gtrpwr.com/downloads.php?do=file&id=9

[Skym]

Capable of up to around 700hp at engine if you push GT2860-5 turbo's on BP 98 octane fuel. Could get more hp on higher octane fuel.

Power -

http://2.bp.blogspot.com/_vhpEGyEVhes/SNcpZUXHl9I/AAAAAAAAA_A/1SD8hIXQv2w/s1600-h/ST+R34+power+1.jpg

Boost graph -

http://1.bp.blogspot.com/_vhpEGyEVhes/SNcCmsctQdI/AAAAAAAAA-w/B82_PbEDkhc/s1600-h/ST+R34+boost.jpg

Tomei Type-B cams with adjustable camgears. Bronze valve guides (Tomei, Naprec, etc), higher lift valvesprings, titanium valvespring retainers, port, polish.

Stock valve guides tend to crack with higher than stock rev limit, so replace them with bronze valve guides.

Stock valves are ok, just do a leak test on head, reseat valve seats that are leaking (or do all of them) and skim head for good headgasket seal.

[Kras]

Initially I was planning on upgrading to 264 with sub 10mm lift, but in the long run I think 272 with ~10-10.5mm lift would be best just in case you want more power etc. Plus 272 is more badass sounding.

Keep in mind though if you go over ~9.5 or so mm of lift you will need to do some machining around where the cam lobes are.

[mitch32]

All good advice. I think I'll get a professional to some porting, I already got a quote for about 1000$ (just for porting).

I'm sure about high lift just cause of drivability.

Also I though that Tomei Poncams don't require springs? If I do get Tomei Type A springs and a set of retainers, do I need to change the valves as there will be more pressure on the valves?

[mcfly]

springs are also dependent greatly on boost. If you plan to run more then stock boost with bigger cams it would be beneficial to upgrade the springs and avoid the possibility of valve float.

It's a way easier job with the head off then on.
If it was up to me i would be finding cams with a low 10.x lift and 270's duration simply because it has been proven to work. Then again mines was strongly rumored to be run massive cams in their "response" video r34.

[mitch32]

Thanks Mcfly, one last question!

If I was to go with Tomei Procams, 270dur and 10.25mm lift (on both intake and exhaust), and Tomei A Spring, would I need anything else (are stock retainers good for those springs)

Basically I'm looking for the best bang for buck setup without going over board. I called Ferrea today and got a 2000$ quote for just valves, springs, locaters, locks, and retainers. I kinda would just like to change alittle as possible but have a good setup. My goals are some lapping, and around 500-550whp.

[mcfly]

you do not need valves for what you want and it will just end up being money wasted. Someone likely has more tomei knowledge then me and can fill you in on whats required.

[Skym]

From what I understand, more cam duration = more mid to peak hp at loss of bottomend on power graph. Valve lift affects torque level.

For upgrading RB26 head -

Tomei bronze valve guide -

http://www.tomei-p.co.jp/_2003web-catalogue/e100_Tbelt.html#valveguide

Tomei titanium valve spring retainer (for Type-B or Type-C valve springs) -

http://www.tomei-p.co.jp/_2003web-catalogue/e094_titanium_vs_retainer.html

Tomei Type-A valve spring for up to 10.85mm lift (look at lift of cams to determine what valve springs are needed) -

http://www.tomei-p.co.jp/_2003web-catalogue/e095_valvespring.html

Tomei Type B camshaft + adjustable camgears -

http://www.tomei-p.co.jp/_2003web-catalogue/e070_cam_RB26.html

[curtisgoodman]

run what i did... procams 270 10.25lift, type a tomei valve springs, you'll need the tomei 1mm+ lifter buckets, replace guides with new stock or bronze, tomei adjustable cam gears, i didnt get retainers cause im not going over 8500rpm and a port and polish plus port matching.

[mcfly]

From what I understand, more cam duration = more mid to peak hp at loss of bottomend on power graph. Valve lift affects torque level.

Now that's assuming you have bottom end power to lose, which on a rb26 it's non existent anyways.

run what i did... procams 270 10.25lift, type a tomei valve springs, you'll need the tomei 1mm+ lifter buckets, replace guides with new stock or bronze, tomei adjustable cam gears, i didnt get retainers cause im not going over 8500rpm and a port and polish plus port matching.

You really don't need retainers for any sub 10 rpm limit, nissans are still very light, a lot more dependent on springs.

[rbs14]

i looking for cams too ... but i will go with a single turbo ... will those procams 270/10.25 be good for my set-up ... i dont know alot on cams ...

i saw some set-up with different size cam(intake/exhaust) exemple : bigger cams on the exhaust side !!! what is the good and bad on that ???

F1-35R Twinscroll Turbo

Turbine Specifications
Turbine housing A/R: .70
Turbine inlet: T4 Twinscroll
Turbine outlet: 3” Vband
Turbine wheel: F1-35

Compressor Specifications
Compressor housing A/R: .70
Compressor Inlet: 4”
Compressor Outlet: 2.5”
Compressor Wheel: F1-35



engine :
87mm mahle pistons
eagle rod
r33 crank
evrething is balance
ROSS harmonic balancer

head:
3angles valve job
port & polish
cam gears

thanks in advance for your help guys

[rbs14]

run what i did... procams 270 10.25lift, type a tomei valve springs, you'll need the tomei 1mm+ lifter buckets, replace guides with new stock or bronze, tomei adjustable cam gears, i didnt get retainers cause im not going over 8500rpm and a port and polish plus port matching.

what is that ??? googled it but nothing