cam shaft upgrade for sr20 det do it or leave it

[meggala]

ok the sr 20 is going in the cefiro turbo is a trust t518z z32 afm 550 injectors gtr cooler etc.
now I 'm wondering whether its worth while doing a camshaft upgrade thinking 256 or 264's. not the 272's.
who has fitted aftermarket cams and can tell me results.

the concensus that my tuner has come up with is its not worth doing unless you have abuilt motor ie head work etc and want to rev it 9000 and want to put a big top mount turbo ex gated turbo.
my thoughts are there will be gains in the mid to top range.
my personal thought is that factory cams are pretty retarded cause they have to meet emmissions so they can't be agressive. so I was thinking the cams to add some more oompp to the car and if I can reduce the boost from say 1.2 bar to 1 bar to make the same power that would be good.


the car will have most of the good gear and the motor will be built when this one dies. but I'm looking to now rather than down the track. rev limit will be 7500 on the motor for now with very occasional 8000 rpm. I would fit a lash killer kit if nessacary

am I dreaming?
meggala

[sssgtr]

Do the 264's. I have a similar duration cam in my KA24, and although NA, i will be getting a similar version of this cam in turbo guise (ie less overlap). Like night and day difference between the 2.
The car shouldn't lose much bottom end (if any) and will make it more enjoyable when giving it heaps.

[IMOA]

I'd suggest new cams and a new tuner.

[TonyJZX]

Originally posted by IMOA
I'd suggest new cams and a new tuner.

Ditto.

The tuner should make use of every opportunity to make some $$$.

But seriously, 20-30rwkW and a much fatter torque curve should be the go with a mild set of Tomei cams or the like.

256/264.

T.

[meggala]

the tuner will fit and tune what he is given :D

but it was an iterresting discussion tony I ahve similar thoughts to you and will probably go the cams.

as for the tuners capability IMOA lets just say he is very adequete.
differnet people have differnet thoughts on tuning thats why I posted the question here.
cheers


btw I'm still looking for some real world results Ie dyno before and aftr figures.

[TonyJZX]

Thing is... the accuracy and 'drop-in' aspect of cams means there's very little after 'tuning' necessary.

The Japanese cams need no dialing and zero fiddling with the ECU to get immediate gains.

I have not seen any documentary evidence pre- and post- cams installation...

I suggest you spend some time on the Tomei JP site.

T.

[IMOA]

With the standard turbo you're getting 15-20kw atw with a mild (say HKS step 1 256/264) cam upgrade on a standard turbo. As you go up the turbo sizes those gains are going to be more pronounced so 20-30kw atw is spot on what I'd expect to see.

[TonyJZX]

http://www.tomei-p.co.jp/_2003web-ca...m_SR20DET.html

Are they all in this price ballpark?

T.

[thehelix112]

IMOA, where is that ~20kw gain in terms of power band? More mid-to-high?
Regards,

Dave

[IMOA]

Originally posted by thehelix112
IMOA, where is that ~20kw gain in terms of power band? More mid-to-high?
Regards,

Dave

Standard SR's die bigtime around 5500rpm, when you put cams in the first thing you'll notice is they pull hard all the way to redline. If you've ever seen a 200sx with cams on a dyno you'll see this very clearly, they hop up on the rollers and scream their tits off at this point. I dunno if there's video of my car at the perf forums dyno day from early last year kicking about here somewhere but it shows this very well. The massive broad spread of power is amazing, once you've driven an SR with cams you'll never want to go back to the standard ones. It's also why I recommend sticking rocker arm stoppers in as with all the power everywhere the liklehood of an accidental over rev increases.

Through the midrange there are still solid gains though, having a quick look at what I've got on my work PC maybe the best example is a comparison between a standard turboed S15 with cams/manifold/tb and a S15 with HKS 2540 and standard cams etc. The standard turboed S15 runs a bit more boost through the midrange (18.6 psi vs 16.3psi) however it's tractive effort is 15-20% higher than the S15 with the 2540. Hmm, comparing the power numbers at 4500rpm the standard turboed S15 has 30kw atw on the one with the 2540. The boost will account for some of that difference but it's clear the cams are working some magic to get such a differential

Re price - HKS dumped their prices around Jan last year and Tomei lowered their prices to match at some point after that (not entirely sure when). Combined with the strong aussie dollar cams are a killer bargain atm, HKS and Tomei cams are actually cheaper than regrinds for the SR! Tomei cams give a little more up high than the HKS and give away a touch down low, there's not much in it though. While Tomei state that you can use their 11.5mm lift poncams in an otherwise stock engine I'm not convinced. I've seen valvesprings collapse over time with this level of lift, I've never seen any problems with the smaller lift HKS step 1's

[TonyJZX]

Originally posted by thehelix112
IMOA, where is that ~20kw gain in terms of power band? More mid-to-high?

Wouldn't that depend on the specs. of the cams?

You can get wild cams and the thing won't idle and won't make anything down below but once on cam, it's a terror.

Stock is something like 240... something in the 272+ would be a real animal.

T.

[meggala]

thanks IMOA thats what i thought would be the case.
I'll look at springs as well the tomei cams are easier for me to get.
and yeah they are great value for the power.

cheers

[TonyJZX]

Lot's of good info here.

Just say you want Tomei 256 cams... would you recommend a full set of matching Tomei valve springs?

That adds considerable expense to the whole deal.

Would there be a local alternative.

I'm looking at this from an RB25/26 perspective.

And would the more complex head in an SR20 be cause for more $$$ for rockers and the such?

T.

[IMOA]

If you went Tomei cams on an SR I'd also change the springs which does add a few hundred to the mix however I wouldn't want to comment on what is reliable on an RB, I simply don't have the requisite knowledge. This and the the fact HKS dropped their prices first which made their cams so popular, you can simply slap some step 1's in and get a great gain. Locally you can get regrinds but these are more expensive than getting the Tomei or HKS cams and I'll take them over regrinds anyday.

The RB25/26 cams are more expensive but still pretty well priced, main reason for this as far as I can see is that they're longer and have two lobes per cylinder rather than 1. The SR valvetrain thing is a bit of a storm in a teacup. Comparing the SR and the RB they both are DOHC using hydraulic lash adjusters, it is the use of these HLA's that limits the revs(Interestingly in both the "race" versions - GTR and GTiR the HLA's are changed to solid). If you want to modify the valvetrain for bigger revs the same mods are done to both, convert the HLA to solid with shims. The fact the SR uses a single lobe and rocker arm whereas the RB uses two lobes and a bucket is pretty irrelevant really even though some try to blow it up as a big deal. It's the HLA's which cause the problems, not the rocker arms.

[Carlos the Jackal]

The (nice) guys at hioctaneracing.com.au sell the Tomei cams for $980/pair for the SR20.


Impakt