25/30 Cam Timing

[iruvyouskyrine]

Thanks to superben I will be putting my adjustable VCT cam gear and adjustable exhaust cam gear on soon. Will be getting a professional to check the cam timing and set it for me. Just after ideas as to what I should set it at as I really have no idea in this area at all.

RB25/30 Neo with VCT, GT3076 .82, 45mm external gate, 3" exhaust, E85, will spin it to 7kRPM

Should be very lively even at low RPM with a smallish turbo like this on it. Is it worth trying to get even more response and even more area under the curve or is it better to try and free up the turbo in higher RPM so it doesn't choke itself?

Any discussion/advice appreciated.

[iruvyouskyrine]

Putting these on soon. Any advice appreciated.

[sleptema]

I'm keen to see the results of this, as I was going to do the same type of conversion. What cams are you going to run? And are you going to get an adjustable exhaust as well? Overhead plenum or freddy/ffp?

Edited January 31, 2015 by sleptema

[steve200b]

I have a similar setup with non Neo head. I set mine at 0 exh and 2 deg retarded with std cams and it fell over Up top. Put in some hks cams with the same settings and picked up 40kw in top end. Still need to play with cam timing on the dyno

[KiwiRS4T]

Set cam timing to zero and adjust on dyno is the best way.

[iruvyouskyrine]

Yep will be getting tuner to adjust them on the dyno was just looking for a rough base setting to get it close.

I had the engine running before and it made boost from very low rpm but just had no power under 5k, but after that it went alright. I highly highly suspect my base timing was way out even though I aligned to the marks on the timing backing plate.

[iruvyouskyrine]

I'm keen to see the results of this, as I was going to do the same type of conversion. What cams are you going to run? And are you going to get an adjustable exhaust as well? Overhead plenum or freddy/ffp?

Standard neo cams. Adjustable intake (retaining VCT, talk to Ben C34) and adjustable exhaust. Using a Greddy style FFP.

[sleptema]

Standard neo cams. Adjustable intake (retaining VCT, talk to Ben C34) and adjustable exhaust. Using a Greddy style FFP.

Well this is perfect, as I will be running almost exact same setup. Only I will be running a china high mount exhaust manifold, type a poncams and a genuine Tomei cam sprocket. Will be interesting to see the results and compare between the 2. Would love to see your build specs/what you did to the block, as I will be starting in a few months.

I had Ben make me a bunch because there are a lot of people chasing adjustable intakes for neos over here. Also the iacv adapter plates. He's a great guy

[iruvyouskyrine]

The block is however Nissan made it back in 1988 haha. Just a wrecker RB30 bottom end with 1.2mm restrictor.

Neo head, standard cams, 6 boost exhaust mani, Greddy ffp, turbosmart 45mm hypergate, Hypergear SS2, Bosch EV14 1000cc, e85, adaptronic is a basic run down.

I have a build thread here in the RB30 section you can suss out. Should be getting tuned on the 16th feb.

[iruvyouskyrine]

Ended up just setting them to zero in the end. Will just let the tuner mess with it.

And yes I know the exhaust isn't on zero, I did move it back.

[iruvyouskyrine]

When I posted the two pics they line up almost perfect and looks like one pic hahaha!

[lcxu105]

I too will be interested in how this goes too. Do you have a link to the build thread?

[iruvyouskyrine]

It's in the projects section somewhere. Getting tuned Monday so will report back.

Will be sure to ask my tuner his thoughts on cam timing RE 25/30 as he has tuned quite a number of them now.

[urtwhistle]

Hmm thats the exact same mod I did to my VCT cam gear a couple of years ago. Every one laughed at me at the time and told me I was rough as guts but there ya go I wasn't crazy after all if others are doing it.

[iruvyouskyrine]

Right. Looking for some info from all you 25/30 boys. *looking at Kiwi and Ben*

My tuner said he hasn't really ever played with adjustable cam gears on 25/30 especially adjustable VCT. So I'm looking for some base settings that we can start at because at $220/hr I don't want to be messing around too long as I'm sure you understand.

Both cam gears are currently zero'd, but as people have said that doesn't necessarily mean they are at true zero. I don't have the time/equipment to degree the cams either. Kiwi and Ben have both said that they think the cams are half a tooth (~4 deg) out when aligned to standard RB25 timing plate marks.

It currently feels like it is slow to come on power and keeps making power right too 7krpm and wants to keep making more. Ideal VCT turn off point is 5500rpm. Both of these indicate to me that the cam timing is out (no idea if retarded or advanced i honestly don't know much about this)

SO. Any advice/discussion is appreciated as this is a topic I am keen to learn about and don't want to have to pay out my ass for the experience

[Ben C34]

I think you're on the right track thinking the cams are retarded.

Based on that the simple option is to advance both. The really time consuming bit comes in when you start to change the overlap by only advancing, or retarding one cam.

It is a tricky one, the more time you spend the better it should get.

I can't remember what ecu you are using. I found using an AFM would mean mixtures wouldn't need touching, so could be done on the road, or heaps quicker on the Dyno. Where a map ecu would need tweaking to keep the mixtures nice due to changing the volumetric efficiency.

I haven't come across the info required to dial in stock cams, and as I have previously mentioned to you when I dialed in my type b cams found they were 4 degrees out. So stock ones would be the same, the thing is its either 4 advanced or retarded. Could be why some 30 builds seem to have super response, running the cams 4 degrees advanced from stock settings, and extra capacity. Considering guys have messed up timing belt installs and run multiple teeth out with the engine still making decent power, it goes to show cam timing issues can be ignored (not that they should, it just doesn't mean the engine doesn't work)

Hope that makes sense.....

Tl;dr

Advance both cams.

[GTRPSI]

Set them to zero and ask the tuner to perform 3 tests.

One at Zero, one 4 degrees advanced and one at 4 degrees retarded from Zero.

Then look at the graphs and take it from there.

Advancing the cams tends to build bottom end, retarding them shifts the whole graph to higher RPM.

See what works in your favor.

[Blackkers]

You could potentially do this on the road yourself if you have a wideband and just data log boost vs rpm and whatever else you feel like. just use slightly lazy timing and slightly rich as well, if afrs are way off then maybe touch them up as you go. Being on e85 means you don't have to worry so much about nuking it

[XKLABA]

I know im not Ben or Kiwi and i generally only deal with shitbox RB26s, but in my experiences shit gets interesting when you advance one and retard the other, in my advice would be advance intake and retard exhaust

If your using the standard exhaust cam i can give you a pretty good idea where to start from , VCT your on your own unless you can give me all the corresponding LCAs of off and on v RPM and the spread between off and on

[KiwiRS4T]

Don't ask me - I never got to the bottom of it. I remember Guilt Toy saying cam timing was the key to power from the RB30 but never had the money to stick my car back on the dyno to sort out why it was making such relatively low power.