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Discussion Starter #1
My car is going to have a lot of bits sorted on it at some point this year & I have noticed that some of the above are going to be released..

Question is, is it 'really' worth the £4k plus fitting its going to cost? Am I going to notice £4k's worth of difference to the way it drives?

It's a hell of a lot of money, so I would expect some pretty impressive results, but information is a bit thin on the ground with regard to them :(

Anyone help?
 

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I would say Chris, that it depends what you are looking for.

If it's ultimate top end power, then no. Think the pro is a 272 9.7 lift. At the end of the day, if you set your car up with normal aftermarket cams, you could set it up for good bottom end/midrange or top end depending on cam profile/cam wheel adjustment.

If like me, you are looking for the broadest spread of power through the rev range with excellent driveability/road manners and the most tractability achievable, then I would say yes. You'll effectively get the best of both worlds. I'm building mine up as a road car with the occasional drag outing so for me this is important. If its an out and out drag car then I probably wouldn't bother.

I can't help you with real world improvements as I haven't tried both, in theory it should be quite noticeable and give you more power lower down through the revs, ultimately top end it may even be restrictive depending on your setup. ie over a certain bhp, a 9.7 lift/272 cam may not be enough.

Regards
Nito
 

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Discussion Starter #3
I would need to check what cams the car has, I can't for the life of me remember. Judging by its history I expect them to be a little wild though..

The trouble is, i'm very much in a position of cake & eating it requirements, I'm still looking to make some decent numbers by ditching the T88 & going with a spec'd up GT42R but part of the plan for doing this is to increase the drivabilty & lower the boost threshold the T88 has, but not suffer towards the top end.

In reality, I know i'm asking the impossible, unless I give it a helping hand (n2o) unless the V-Cam would make a big difference to the low down torque & midrange drivabilty, but then as you say, will it restrict towards the top end?

My car is in reality 90% a road car, but I want it to run some pretty serious times when finished, it doesn't get driven much, but I would like it to be more road friendly for when it does...

I'm not sure if it will work ultimately..
 

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4k!!!!!! for a cam!!!! I could rebuild most of my car for that - with proper bits.

You could buy an std R32 GT-R for a bit more and save the T88 for the wild days and empty roads.

I have T04R with 272's mid lift and OS triple - yes it's a dog in stop start traffic but as long as you stir the stick and keep your foot planted it drive's just fine. For the improvement of the V-cam I wouldn't pay more than £500.
 

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-C- said:
Question is, is it 'really' worth the £4k plus fitting its going to cost? Am I going to notice £4k's worth of difference to the way it drives?
Although I can't provide a perfect back-to-back analysis of the VCam effect, I can give you some idea of the potential improvements you can experience. IMHO, the money is worth it for a strong street drag tune RB, providing the person doing the setup and tuning really knows their stuff.

In the graph below, the only material differences in my everyday pump gas setup (obviously besides the addition of the VCam unit itself) are as follows:

(1) External wastegates routed to atmosphere instead of back into the exhaust stream; and
(2) ECU re-tuning for responsiveness instead of a neutral map.

http://home.att.ne.jp/omega/hipogtr/gallery/cat3/VCamEffect.jpg

As you can see, despite the nominal impact on peak hp, the impact on torque production is significant. Similarly, the area under the curve is much improved in both cases.

One caveat - the VCam that I'm using is one of the limited run versions. How things look with the new versions being released by HKS is anyone's guess - apparently its quite a different setup.

Hope this helps.

Cya O!
 
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Gio,

yeah I am lucky to have a limited run kit, that should run later tonight or tomoz morning.

From what I have heard the latest system are quite low key to the our systems , I think it will just be a 3/4 position cam system not like our multi mappable systems.

I hope we can get the results like yours ;-)

Yes they are expensive but they do what they say on the box.

PS it is not just a cam it is a lots of stuff (electronics, hydraulics, cam pulley)


Mark
 

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I wonder how different the production models will be? Judging by the prices the're not really much cheaper than the limited V-cam.

Here's hoping that they're not!

Nito
 

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Discussion Starter #8
Thanks Gio!

It does look like an impressive mid range gain - It doesn't seem to affect the top end either. Do you fell since going with the bigger turbo's you have lost some of the benefit of the V-Cam or is it still comparable?

Is the lack of relative adjustment likely to be a big limiting factor does anyone know?
 

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Does this V-Cam only effect the timing of the inlet cam, or both? Anybody know what timing adjustment range they have, and is it adjustable?

I have seen the figures HKS post on thier site, not necessarily for RB's, but it doesn't look that impressive. Many of the comparisons are against STD cams, and the gains are minimal. Most low duration high lift cams would give similar results for less over stock cams.

Years ago, some co. made a centifugal adjustable cam pulley (not for an RB). Basically, as the revs rose, the cam was advanced automatically. This also widened the cam powerband much like the V-cam, but cost a fraction of the price. As the inlet cam is accesable on the GTR, this could easily be done.

I guess this is the type of mod you only buy, when you have all the others already. What i mean is, a capacity increase, ECU plus proper mapping, head porting plus manifolds, more efficient Turbo, etc all provide better response, and perhaps give better bhp/£ than a V-cam.

If they brought out the Honda V-tec system for an RB, now that would be worth £4K :D
 

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I can see it improving driveability a lot, but not 4k's worth, well not unless you someone who pays 4k for relativly simple stuff like many do.

Better bet is bringing the general engine spec up to date with that 4k, rather than 4k on one spangly part which is trying so hard to compensate for a poor overall spec.

(ie bin that old mitsu truck turbo)
 

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Should be a massive improvment with a modern turbo and good mapping.

What spec cams do you have?

TBH unless you mega rich, I cant see 4k ever being justified for that!

I really would love it tho
 

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Discussion Starter #15
IIRC (im not 100%) they are HKS Step 2's

In 280, 10.2mm lift
Ex 272. 10.2mm lift

I'm not mega rich no! (wish I was though!!!)

Philip said:
Chris,

What manifold are you going for?

Phil
Phillip - a RIPS one with single TB :)
 

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Discussion Starter #18
Stavros - thats the full on drag inlet, I didn't want one quite so big...

IIRC this was the one I was looking for..

My understanding is the capacity of the plenium is smaller, so as not to lose as much responsiveness (and the fact that my car isn't a drag monster) :)



 

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Abbey M/S said:
I hope we can get the results like yours ;-)
I'm sure you'll put the big numbers together, Mark. :) Keep us posted on your results as there are very few people with VCam results on the RB - even less with back to back results that everybody is most interested in.


-C- said:
Do you fell since going with the bigger turbo's you have lost some of the benefit of the V-Cam or is it still comparable?
Speaking only for the VCam that I have, Top Secret indicated that you should feel the impact of the VCam regardless of your turbo sizing. How much has as much to do with the tuning as all the supporting parts. In my case, I don't get a lot of low range benefit due to the size of my turbos. This is different to the typical comparison that HKS uses where they get a big bump around the 3,500RPM zone using responsive GT-SS turbos. Just FYI, don't refer to the before/after VCam comparisons that HKS advertises for engines that already come VVT-i equipped, such as the VVT-i 2JZ, as the RB26 impact is quite different.

On a related note, if you go with a well designed single throttle plenum you may actually see a bigger bump in mid range torque than you would by sticking with the stock setup (at the expense of transitional throttle changes). This is due to the better flow characteristics of the single throttle plenums. This accounts for some of my heavy mid range torque number.

One thing to keep in mind with the gains that I saw is that the neutral map I'm comparing against is not optimized for torque like the VCam one. Consequently, the net gains at any point in the graph are a little exagerated from a real back to back analsysi (i.e. don't expect 20kgm of torque gain from simply adding a VCam unit). Also I run Step 2 272s on both sides of the head which, according to HKS, is an optimal match for the VCam.


-C- said:
Is the lack of relative adjustment likely to be a big limiting factor does anyone know?
I'm not sure about the new VCam model but, as Mark pointed out, the likely differences between the new model and the original may be significant. Like the resolution on ECU maps, I would hazard a guess that the lack of adjustment will impact the shape of the end curve, if not the overall power/torque numbers.

NISFAN said:
Does this V-Cam only effect the timing of the inlet cam, or both? Anybody know what timing adjustment range they have, and is it adjustable?
It only modifies inlet cam timing and, from memory, I believe the working range is 90-130 degrees ATDC. Maybe Bean or Abbey can confirm this?

Cya O!
 
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