Which Poncams To Use For A Particular Application

[allthewaytotheskyline]

Hey all sau'ers...

Im currently upgrading my r34gtt rb25det neo, with bolt on mods.

I will be using a hks 2835 pro s as well as all supporting mods.

Now ive spoken with my tuner and he recommend for tomei poncams thats i use 252 degree 9.15mm lift as i will prodominantly be driving on road (mind you its my weekender toy) and the odd track day a few times a year.

Ok well im NOT looking to fry my engine, so i dont want to be sitting off the rev limiter and high rpm's as ive been told will tend to fail a lot faster and in turn cause engine failure.

Although contradictory to all that, i want to be able to get a fat torque range throughout the mids and have minimal lag with the hks 2835 pro s but as well keep some power up top for when needed. (eg qaurter mile runs etc)

now my concern/enquiry is even though my tuner has recommended 252 9.15mm lift poncams i have also heard that 260 9.15mm poncams work a treat...now im not 100% certain which would be more beneficial to my application, as ive said above i am mainly wanting to minimise lag, keep the torque and maximise the mid range and not have to rev the hell out of the engine to only make power in the higher rpm's which in turn would cause more wear and tear and failure in the long run. (alot faster that is)

what is your opinion on all this?? (obviously from experiences)

from what ive read....sydneykid tends to have a great understand of cams and how they may/can benefit an engine so im hoping he may make an appearance to this thread.

any help would be much appreciated.

thanks, Bass.

Edited May 3, 2009 by allthewaytotheskyline

[White GTS-T]

The longer duration on the 260's will move the torque band further up the rev range. For your application, you want the 252's.

[SS8_Gohan]

unfortunately, SK is no longer with us on these boards, so if you dig up old threads with stuff he's written, that's the best you're going to get.

don't know anything about poncams, but maybe try the RB25 turbo upgrage results thread, and search in there, see what other people are running, and what their graphs look like.

good luck

[neo32]

i put the 260 in my car made more power everywhere

brings on boost earlyer as well

[allthewaytotheskyline]

i put the 260 in my car made more power everywhere

brings on boost earlyer as well

hmmmm intriguing, which turbo were you using and do you happen to have a before and after dyno graph to compare against??

also how much earlier did the turbo come on??

cheers, Bass

[allthewaytotheskyline]

unfortunately, SK is no longer with us on these boards, so if you dig up old threads with stuff he's written, that's the best you're going to get.

don't know anything about poncams, but maybe try the RB25 turbo upgrage results thread, and search in there, see what other people are running, and what their graphs look like.

good luck

ive searched all the poncam thread and need more particular evidence on rev's and lag...also my particular set up with the hks 2835 pro s.

unfortunate that SK is no longer with us as he was quite the resource for information (i wondered why when i tried to message his inox it said it was full)

anybody know how to get in contact with him???

[allthewaytotheskyline]

well after speaking to a few reputable workshops/tuners i have been advised against the 252 degree 9.15mm lift poncams and have been directed to the 260's as the 252's will barely be noticable and depending on the tuning the 260's should be perfectly fine for midrange and all over torque as well as brining on boost some what earlier then standard cams.

if anyone objects dont hesitate to speak up.

thanks for your help peepz.

Edited May 4, 2009 by allthewaytotheskyline

[NickR33]

I had the 256º duration, 8.5mm lift Poncams with a 2835 ProS... was a nice combo... but I don't think Tomei make the 256º for NEO... anyway you want as much lift as you can get without having to mess with the head (new springs, buckets ect) and the least amount of overlap to keep it making power down low... those 252º have a good amount of lift they would be a nice street cam, don't rule them out

[SS8_Gohan]

when i was looking, i think i only found 260 degree poncams from Tomei for the NEO, and nothing else.

[aDrew_C]

I'm going HKS GT 2835 Pro S on an RB25 as well and for cams have been told to keep the lift as low as possible if response is a concern. I think I'll stick with the 256 degree 8.5mm lift tomeis from nengun, good price too. HKS are 8.8mm lift and a bit more expensive.

[Simonster]

AS a sough rule of thumb, for every 14 degrees of extra camshaft rotation, ie increasing from 240 to 254, your peak power will shift 500rpm to the right in this case.

That said i went from the standard 240 cams and 7.8mm lift to Tomei 256 and 8.5mm and my engine is still making power at 8000rpm.

[cankas]

Have very close to the same setup but i have a garret equivalent, cant remember exact numbers, and have the 260 cams, power around town speeds is fine it is a little lazy but hit 3500-4000 and it will pull all the way to 7300. In safe tune im getting 285rwkw and on country trips i can get 10.5L/100km.

[allthewaytotheskyline]

im gonna try my luck with the 260's only as i was told the 252's will barely be noticable...and seeing that my 2835 pro s has a .68 rear housing that will bring the lag down substantially...so i will be able to bring the 260's in without harming much in the lag section.

what do you all think?

[joeyjoejoejuniorshabadoo]

that you will notice the low down loss more than the up to gain....

[allthewaytotheskyline]

that you will notice the low down loss more than the up to gain....

well what if i was to use a exhaust cam gear to bring it back a few degree???

[joeyjoejoejuniorshabadoo]

that will help

i'm just not a fan of cams... for a street/track application where you want quick boost response...

IMHO (and many people disagree) the $ vs kw is not worth it for cams.

ECR33 Series 1 (RB25DET) - Duration: IN,EX 256 Lift: IN,EX 8.5mm AU $ 837.43 AU $ 1,019.10

Nissan RB26DETT, RB25DET, RB20DET Exhaust Pulley AU $ 213.39 AU $ 247.19

that's nengun's current pricing there... so that's $1250ish plus the price of dialing them in on a dyno all for maybe 10rwkw...

imho, get the ex cam gear and spend the rest of the money datalogit/e85 (remembering i make 311rwkw on the same turbo)

without tuning costs, cams will be around $100/kw and e85 is $15/kw

or spend it on on handling... i'd be willing to bet there's some suspension stuff you need

[Simonster]

AS a sough rule of thumb, for every 14 degrees of extra camshaft duration, ie increasing from 240 to 254, your peak power will shift 500rpm to the right in this case.

That said i went from the standard 240 cams and 7.8mm lift to Tomei 256 and 8.5mm and my engine is still making power at 8000rpm.

[Simonster]

that will help

i'm just not a fan of cams... for a street/track application where you want quick boost response...

IMHO (and many people disagree) the $ vs kw is not worth it for cams.

ECR33 Series 1 (RB25DET) - Duration: IN,EX 256 Lift: IN,EX 8.5mm AU $ 837.43 AU $ 1,019.10

Nissan RB26DETT, RB25DET, RB20DET Exhaust Pulley AU $ 213.39 AU $ 247.19

that's nengun's current pricing there... so that's $1250ish plus the price of dialing them in on a dyno for maybe 10rwkw...

imho, get the ex cam gear and spend the rest of the money datalogit/e85 (remembering i make 311rwkw on the same turbo) or on handling (i'd be willing to bet there's some suspension stuff you need

Agreed

[CEF11E]

that will help

i'm just not a fan of cams... for a street/track application where you want quick boost response...

IMHO (and many people disagree) the $ vs kw is not worth it for cams.

ECR33 Series 1 (RB25DET) - Duration: IN,EX 256 Lift: IN,EX 8.5mm AU $ 837.43 AU $ 1,019.10

Nissan RB26DETT, RB25DET, RB20DET Exhaust Pulley AU $ 213.39 AU $ 247.19

that's nengun's current pricing there... so that's $1250ish plus the price of dialing them in on a dyno all for maybe 10rwkw...

imho, get the ex cam gear and spend the rest of the money datalogit/e85 (remembering i make 311rwkw on the same turbo)

without tuning costs, cams will be around $100/kw and e85 is $15/kw

or spend it on on handling... i'd be willing to bet there's some suspension stuff you need

Actually, thats some pretty good advice right there.

I have been tuning RB's for years and cams never do what the owner expects unless they are making close to triple stock power outputs of the motor. or is you intend to run massive boost. for anything less than 18psi and your turbo choice i would forget about the cams. especially on a neo.

spend the money on an exhaust manifold. or as joejojojojojojojojojjojojojojojojoj..... says handling

[discopotato03]

I can tell what SK found on their R33 RB25 and that was that headwork really paid off , with the standard cams and turbo .

At the time he told me that cams were an easier way to partly achieve what better porting and valve sizes do .

Personally I would err on the conservative side with cams for a couple of reasons .

First the thing gets wheeled out for a spin on the weekends so needs to be a nice drive on the street , torque where its needed most makes a much easier car to live with .

Secondly these RB25's are a single throttle inlet system so unlike an RB26's individual throttle system won't cope as well with longer duration cams and reversion .

Thirdly if you make the thing rev other expensive things need to be done to keep it reliable over time . Wear and tear lives at higher revs so if you can find ways to make torque at lower revs it should cut down on the wear/tear thing .

Personally I would put the money into headwork even if it meant buying another head to mod and fit when convenient , cams I'd do second and turbo last .

Thats what I'm doing with my R33 only the Poncams are in the head waiting to be fitted .

I guess I'm lucky , I got to see Gary's progress with that RB25 and it was done in stages so it could be still used between steps .

I only have one VG30 turbine housing and I wish I had two because if I did id use it with the std RB25 turbo when the head and cams go on , I want to keep mine for a Hi Flow if I go that way .

My 2c , cheers A .

Edited May 5, 2009 by discopotato03