Jump to content
SAU Community

Recommended Posts

Ok Ill cut straight to the chase i have searched and i swear there was a thread on camshaft choice vs turbo i could be imagining this, im after some next stage engine mods to increase power and be very benefitial for my result.

So far ive come to an end of where to go to increase power in my setup.

Major details:

RB25det

Forged Pistons Rebored to rb26 size rebuilt bottom end mild pnp head and full head service.

Turbo: Hks 3037pro S IW

Inj: Nismo 555 cc injectors

Driveline: Supporting mods for this running on standard gtst diff including a better clutch to handle the power

Running splitfires

Apexi PFC

G-reddy EBC tuned to 16.5 psi

Tomei 248 Lp/h Fuel Pump

FMIC

Apexi Pod

Exhaust: Custom Split dump to highflow catco cat to 3.5" back

The tuner recommends either cams or New plenum both of which he says will increase over power figure that i have

At the moment 221 rwkws with 1561 N.M Torque on dynologic dyno. With wheel spin?

I want to increase this a fair bit and i find that cams are probably the next step, But with what choice should i go in regards to turbo and engine setup. Either tomei 256 in/ex 8.5 Lift or hks setup both choices either 256 in/ex 8.8 lift or combo it with the 256 in 8.8 lift and 264 ex 9.0 lift. Which would give my setup the benefit of best result. Hence im after some input here, On that note with plenum would it increase power or is that a fad? I have seen results seen past 300rwkws im saying will it increase power not will it handle the power.

Just some recommendations and ideas would be good on what path to take here

Cheers Guys

Adam

Link to comment
https://www.sau.com.au/forums/topic/161076-what-cam-choice-should-i-go-for/
Share on other sites

Well i had the full rebuild and ran out of money when it came to the cams.

It has a custom plenum and the rest.

Running around 450rwhp with standard cams.

personally you are paying for the name when it comes to hks.

I have noticed that you can pick up a set of tomei cams for $750 on ebay, which will do the job fine as i have heard good reports on the tomei cams.

personally you are paying for the name when it comes to hks.

On an s1 rb25 you are paying for the extra lift and duration on the exhaust side. Or you can rip the head off and get bigger exhaust valves put in and use tomei's which don't offer anything other than a 256 for an s1 engine.

Id recommend hks 256/264 from experience with an otherwise internally stock engine. I initially went from 238-268rwkw with no other changes by installing these cams with a similar size turbo to yours.

I'm now making 288rwkw just from freeing up the exhaust some more after the turbo.

Taken from another post about camshafts by URAS:

yeah but zero on the gears is not often zero on the cams, HKS especially need dialling in to get a "real" zero. some supra ones i used on this car a few years back were ~4 degrees out.

Questions:

-Does that mean for a rebuilt engine with lower/higher compression setting the tomei cam shafts to '0' degrees would not get the best results as that for a internally stock engine?

-Can you adjust the camshafts setting without an adjustable camgear?(or do you have to purchase adjustable camgears to adjust them)

-Any guys on SAU with a rebuilt lower compressioned RB25DET running aftermarket camshafts? What gains/results have they got?

I was also led to believe the 256/264 combo is a good option, Im guessing a little playing with the dialing for these would needed because of mismatching? But as you said SK tomei seems to be the way to go?? Bah i wish i had a little more on this can others state results on similar setups and experiences? SK have you tried the 256/264 combo on any of your engines, just wondering how you went if you did and if there was much if any dialing needed setting for this type of combo?

Cheers Guys

A

After a little research I went for just a HKS 264 on the exhaust side with a standard inlet for an old R33 gtst. It proved very effective on a mild engine , stock turbo & intercooler. I have attached a graph of the 'after' of a run in tune for my old car. The shape is a little different to what you expect from the stock cams.

This tune was mega conservative on timing(run in tune) and low boost (6 psi) 175rwkw at 5,500 (the top end power was tuned off on purpose). This was a stock turbo + intercooler + SAFC II. Afterwards the car was tuned to make the better part of 180rwkw by around 4,000rpm @ 10psi for the new owner. The car came on boost very hard, I estimate it would have made around 200rwkw by 5,500rpm on the same boost with a Power FC and some more tuning. The guy who bought it had not owned a performance car before and wisely took my advice to leave the power where it was till he got used to it. It's a shame I don't have that dyno graph anymore. And I lost touch with the guy who bought it.

I would certainly vouch for the tomei offering for 3037pro, more than the smaller stock turbo it will really wake up with a decent size of cam on both ends. If you decide to squeeze more top end out then with higher RPM a set of beefy valve springs to go with them is a good move too.

Do get some cam gears for them all the same since we have new fuel offerings being made availible (like the ethanol variants) which you can capitalise more on with an appropriate adjustment to cam timing.

post-271-1174380319.jpg

Edited by rev210

Thats what i thought, tomei seems to be the win so far, but wouldnt mind a little more input based on the hks combos as im guessing would work on the same principle but if it is say shown that it is a better selection vs tomei that the way i will go but if it needs improvement compared to tomei ill go that way??

Cheers

A

Create an account or sign in to comment

You need to be a member in order to leave a comment

Create an account

Sign up for a new account in our community. It's easy!

Register a new account

Sign in

Already have an account? Sign in here.

Sign In Now


  • Similar Content

  • Latest Posts

    • In a few years from now, you'll regret that. It'll eat away at you, knowing the truth of the ugly hiding beneath the beautiful exterior... 馃槢
    • I don't think the G2 profile is particularly dangerous for the engine per se, more just are you actually ok with the turbo lag trade-offs? If the answer is yes then go for it. I personally don't think I'd be ok with it because I spend so much time at lower RPMs and I really enjoy the feeling of being able to stay in 5th gear on the highway and just roll into the throttle to get boost. Or staying in 3rd gear on "gentle canyon cruises" without feeling the turbo lag too badly. The 525 pump should be able to run flat out on factory lines but I would bet the pressure drop from pump to regulator is quite impressive. I don't know how much it would be exactly but I've seen figures like 30 psi thrown around.
    • It's interesting seeing everyone talk about what level of risk they are happy to tolerate.  Building a GTR always has a level of risk, you could be that lucky guy that drops 20k on the engine build alone and still has the thing go pop on the dyno. Life is fun like that.  The way I see it, the thing is a toy to be enjoyed. I'd be happy to turn up the power on stock motor and limit the risk with sensible tuning and engine protection. If it still goes pop, it is what it is. The car isn't a daily driver so it can happily sit while a plan is made to sort it out.  Given this thing will be a street car only, I really feel it's worth the (relatively small if managed well) risk to turn the power up to around 350KW on e85.  I don't think anyone getting into the skyline game now is doing it out of logic. Surely it is a purely emotional decision so I'm not sure how important it is to think about the engine build logically. The heart wants what it wants.  @joshuaho96 little note for Josh, I run my 525 pump flat out all the time and through the factory lines without any issues. (excluding the melting connectors, that's sorted now. we'll pretend it never happened lol)
    • But the Nexus S3 is very expensive and won't be as purpose-built for the application as a separate electronic boost controller :^) More seriously my pet issue here would be that the Walbro 525 running at 100% duty cycle is going to require more FPR than the stock setup can handle. I'm also pretty sure from what I've seen elsewhere you might want to slow down the pump regardless unless you're going to come up with some way of upsizing the fuel lines coming from the fuel tank. Factory 8mm fuel line doesn't actually flow very much if you want to keep pressure drop down between the fuel pump outlet and FPR. If you really want to "keep it simple" I would run only as much pump as you need and source a fuel pump controller to slow down the pump in the vain hope of being able to run stock-style FPRs which are pretty dinky. Or just use the HICAS lines and it should be mostly fine. OP should also really think hard about what profile they'd want out of the turbo. My pet choice here would be the G1 profile rather than anything higher power but YMMV. I already think ~stock turbo lag is pretty bad so I don't want to make it worse. In "gentle canyon cruising" I found that I spent a lot of time around 4-4.5k RPM. I also recommend DIYing labor if you're detail-oriented enough. Costs are high for labor + if you do it yourself you can be your own quality control.
    • GTSBoy is again on the money. My actual advice? Sell the car. (really). For what it's worth as is, you can sidegrade into something much better. If you care about function then this is the actual move. If you want a Skyline to perform, set aside about $100K to do it. This is NOT a typo. You will see right away these are two very different mindsets. Realistically we're talking full restomod for any Skyline still kicking around. Have an honest think about which one you are.. and what you want to do, and how much you want to invest in this (with no return).
  • Create New...