Big Camshfats And The V-cam System

[Faid]

hi there, im getting a bit tired waiting on boost in my car, i hit full boost at about 5200, current mods are HKS T04Z, ported & polished head, 1mm oversize valves, HKS valve guides, tomei valvesprings, jun retainers, etc (ie a very very expensive head, ticked off a lot of cash to send it away to be build). the cams that i am running now are the tomei poncams 260 duration and a 9.15mm lift (if im not mistaking). and i am runnign close to 600awHP (450awkw) (dont have a dyno, to get the correct figure). i am getting tired driving my car in traffic, off boost the car is bullshit, and when it does hit it is the devil himself. what i was wondering if i should step up to bigger cams like the HKS ProL with 280 deg and a 10mm lift (or so i think), or should i go even more radical like the Tomei Procams with different duration for intake and exhaust, such as 280deg@ 11.5 mm lift IN and 290deg@ 11.5 lift EX. i allready have a camgear for both in and ex. and oh yea before i forget to ask, i have been doing some research and i have come across the HKS V-CAM system, like the VVT on the S2 RB25. i would like to what your opinion is about this system on the RB26. Might just try it, from a theoretical point of view, it looks interesting. but then again i am new to my RB26.

[govich]

The V-Cam system is probably your best bet (though it is really really expensive). Normal cams with a set duration/lift are always a compromise (ie. you give up bottom end torque for top end torque or vice versa). It's the reason variable cam timing systems were developed, like the HKS system.

[paulr33]

they look ace

[Faid]

what about if i run the VCAM on my current setup, with the poncams. will it help my off boost response?. and i want to be ready for the upcoming drag race over here. some of my friends bluffed me last time when i brought my car to the race and dindt participate. but ill have a little surprise ready for them when i show up in december. i do have a sweet rev range i get till 10k with a 10200 revlimit. or ill buy a set of big cams that only give me power in the top of the table and after the race ill swap my poncams back in.

[Angus Smart]

I'd definatley go the v-cam system if you have the coin to pay for it.. when i get home i will try locate the best motoring issue that covers it. i beleive it had subtitles. and was rather interesting.

tho testing was only done with v cam on and v cam off. so the system isnt really tested against a car with same setup and just cams.

it does seem when vcam is on that you will gain alot more response down low without loosing top end power.

[RB30-POWER]

The gain in low down torque would still be very minimal in reality.

If you want response either get a smaller turbocharger or convert the engine to 3L.

Or else you will be out of pocket and still have a laggy mofo of an engine.

[rev210]

the V-cam adjusts the cam timing on the intake cam alone. It doesn't morph the shape of your cam or do anything magic. You are still stuck with the 260 deg duration and 9mm lift.

So if you want to see what benifit the V-cam can make it's easy enough to alter the intake cam timing on the dyno to see what bottom end you pull out of it by adjustment. At that particualr timing the top end power will be lower but, you can see what difference there is to be had. You 'might' get the boost on 500rpm lower if your lucky.

The other thing is that the exhaust cam timing has a relationship to the intake cam timing so you need to set it according to the shape of the power curve you want.

Going up in cam size will give some improvement. More cubic inches will do it too.

If it's the 'time' you are waiting for the turbo/engine to hit the fun, then you can also focus on areas of 'response' like taking rotational weight away. Carbon fibre tail shaft, light weight clutch/flywheel, pulleys and balancer, electric fan, forged rims.

If the engine takes the same 'time' to rev to 5200 after doing response mods that it used to take to get to 4200 rpm then the car will 'feel' like it would if you had done the same thing with something like big cams or V-cam alone. Thats feeling and accellerating just like getting airflow mods to bring the boost on at 4200rpm.

Of course you can do both too.

[R31Nismoid]

~5200 is a little higher than i would imagine a t04z to be doing its thing.

Based on the results in the dyno thread that is.

You really need to get it on a dyno dude, how can you know what the car is/isnt doing?

[Beer Baron]

Yes, I would suggest spend some time with cam gear adjustment. on my RB26 playing with cam gear adjustment brought on boost around 400rpm earlier, and made approx 30kw more midrange power.

[ReQuieM]

Cams wont help your bottom end, generaly. The extra duration will pump the top end while killing you low end. Stockies would be better for the low end.

Displacement, intake runner length, exhaust mani runner length and turbo size would be your best bet. I'm not familar with your turbo but if there is a ball bearing version that should help spool time.

[ReQuieM]

yeah the gears will help, tho I'm not a big fan of fkn with the cam timing tooo much. just to dial in a nice curve.

[Sydneykid]

Are there any dynos in Surinami?

cheers

[Faid]

unfortunatly there arnt any dyno's. and what i was wondering now, if one of you guys could help me out with a RB 30 conversion. my T04Z hits the full boost around the 5200 because i dont have much more displacement thaen stock. i use stock size ronds, stock cranck, the only thing that is oversize is the piston. but taking away rotational mass, is sounding interesting too. where can i buy a full setup RB26/30 with forged pistons, rods, the works, and i dont want to be fussing around another engine, i jsut want it built and sent over, im getting tired of my car. but when i get on boost and the turb built op inertia, it is fkin quik to respool. when my friends and i go out and we come back to late night empy streets, i drift nearly evry traffic light stop, drift while cornering. This car is my dream car with a dream setup, the only thing that bothers me is the lag down low, other then that, i love it when people move further on the sidewalk when they hear a skyline with atmo wastegate & screamer shoot by at 10k rpm, its just heavy traffic that bothers me. and oh yea beer baron, i think ill take your advice with playing around with the camgears, got them with the cams but i put them on the 0 position.

[Tangles]

You're gonna hate me 4 sure:

How about selling the big turbo, utilise a smaller turbo, lose maybe 100awkw and have a much more driveable car? lol.

Maybe not, but if it isnt driveable (ie if she's a pig at normal traffic speed) as it currently might be with your current setup, then whats the point? Biggest HP means nothing if you cant comfortably drive the car in traffic.

.............. although I know sweet-FA so ignore my comments But something to think about.

EDIT: Or install an Automatic gearbox with a highish RPM stall converter, maybe?

Edited October 9, 2006 by Tangles

[Faid]

what u are saying is true, run smaller turbs and loose the lag. but there are ways to spool this turb. just need to docter them out. but once 450kw gets to ya, the only way is up.

[Tangles]

I dont think its the 450kw that you get addicted to - its the Rush as such, been there with the fireblade (see link below) and not much can replace that feeling I assure you ........ barring a V8 Supercar or something, so yeah I totally understand.

Good luck spooling it up in the late 3800's - early 4000's She'd be a fine mistress then Im sure

[Sydneykid]

what u are saying is true, run smaller turbs and loose the lag. but there are ways to spool this turb. just need to docter them out. but once 450kw gets to ya, the only way is up.

What exhaust housing do you have on the T04Z?

cheers

[R31Nismoid]

what u are saying is true, run smaller turbs and loose the lag. but there are ways to spool this turb. just need to docter them out. but once 450kw gets to ya, the only way is up.

You have no way of knowing you have 450awkw dude.

You cant really say unless you have some 1/4 runs with the mph into the 133-135+ region which is what you'd be expecting from that kinda power.

You also later delivery (as ive said) than you ideally should. You make no mention of a cam gear, and thats the first thing i'd put on an RB26.

For the lesser headache, i'd just get a smaller turbo if you cant fix it.

You'd be hard pressed with a fat donkey midrange to want peak power ever again. But you do seem to have a silly amount of money which i guess you cna throw around if you want.

IMO - Once you have XXXrwkw of unresponsive power and then have XXXrwkw of responsive power with a smaller peak... you wont go back.

There is no real point in making a 26/30, its going to require even better tuning to make the most of than what you have now, which you can still get a lot more out of.

[T04GTR]

corect me if im wrong. but im pretty sure the v-cam systen uses pretty small cams with not much lift.

ie. your stuck with then

because of valve interferance isuues.

[Faid]

well i had my car clocked with the system that they use when a drag race is held, and i clocked in at 128MPH, they are using some sort of laser detector, just like the cops use when they monitor your speed. and i do have camgears, i got them with the poncams (came as a set). but to have my car put on a dyno ill have to make a trip to french guyana, there they have one, as two cars that race over here got dynoes and tuned over there. will make that trip at the end of the year when i have some free time. as for the money that i have to throw around, i work very hard for evry penny of it. its just like people that collect postage stamps, ie cost a lot of money, but they have plesure in it. oh yea gary i have the 0.81 housing

Edited October 9, 2006 by Faid