Just fitted Tomei Poncams in RB25DET

[Bass Junky]

I want to kill myself.

[Muz]

Hey Bass Man, this is extremely interesting as I remember reading HPI doing the mods that you have done and they claimed to have made a substantial gain with just the cams and an even better gain when they changed turbo's. Buggar me, I should have sold my poncams to Adam when he wanted to buy them :-)).

Cheers

Muz

[Dale FZ1]

On my old R33 gtst I ran a standard inlet cam with a larger duration and lift exhaust cam. There was an improvement through the power band. I did my selection based on advice from someone who does camshafts for a living.

Can you share the cam specs, and was the mod actually worthwhile in terms of seat of the pants and $$ spent?

[paulr33]

what a spew, sorry to hear. there must be a logical reason for no power gain? once agian sorry to hear

[R31Nismoid]

aren't the poncams designd for a turbo which is bigger anywasy, hence more airflow etc.....

hence wouldn't theu benefit from this rather then improving stocko setups

pretty much.

The 800 can be better spent depending on what mods you already have

that one is my personaly thought (before people start jumping)

Will be interesting with the new turbo...

**although, insert disclaimer** it will be hard to say as you will already have the CAMS installed. My bet is they wouldnt make too much difference. Something, yes. A lot... debateable.

Stock 33/34 25det cams are pretty decent.

Mine only drops 10kw right at the top end (over 7000rpm), thats with the 270rwkw tune i run around daily on.

I'll put some cams in mine at some stage when i have some cash, being they are the last things to touch on my car mod wise as i've done everything else

[GTRgeoff]

I want to kill myself.

Hey! Mate, we don't wanna start a suicide watch.

Seriously it can hurt when it goes a little star shaped, you have expectations and they aren't realised. Plus I bet the better half is scolding you.

There is always someone worse off. Think of the 3500 on engine rebuild i spent 10000km ago, then the 2500 on TT conversion, plus all my labour and since it appears the front turbine shattered I'm up for a new engine rebuild and a set of turbos as the front 3 cylinders are down to 25 psi.

Now you're smiling right ?

It'll all be good Pete.

[Abo Bob]

I'm cringing for both of you.

[GTRgeoff]

Methinks GTR long engine will be cheaper.

[BBQ]

Bass,

I seem to think that they cams you have chosen are too big for your application, Those style cams would work well if you are planning on running a Gt30 Size turbo, as the boost level would be around 25 - 30 psi to take full advantage of the cams.

Duration IN,EX 252 Lift 9.15mm, may have been a better choice for a high flow setup.

But if your tunner is good enough you may be able to gain a few HP out of the high flow with your current cams.

Good luck.

[Sydneykid]

I felt a disturbance in the Force...........

No hang on.

A disturbance in the Force I felt

That's more Yoda like isn't it?

I have never tried 260 degree Poncams with a standard turbo, we have used them with a GCG ball bearing hi flow and a GT30 on R34GTT's. Made good power increases everywhere, particularly in the 4,000 rpm to 6,500 rpm range. Even at the same or lower boost levels (less restriction, more airflow, lower boost).

So what's different about the standard turbo?

1. Maybe it's simply out of airflow, that would mean the same/similar power

2. What sort of power are we talking about here?

3. Did the boost drop?

4. Does it drop off at high rpm?

5. What do the A/F ratios look like? Std cams Comparison?

Some things to try (maybe you already have)

A. More boost? It may move the airflow into the cams' working range.

B. Less boost? It may move the airflow into the turbo's working range

C. Advance the ignition timing? If I remember rightly we had to advance the timing quite a bit on the Neo with the hi flow. It didn't ping at the same timing as when it had the standard cams.

D. It also went a little rich on the A/F ratios when we changed the cams, so we had to lean it off a bit. It was making more airflow (as per the AFM) but at lower RPM, so it needed some tuning at a number of load points. Not as much change as the ignition timing though.

Changing cams requires a lot more tuning time than many other mods because it changes the fundamental relationship between the airflow, rpm and combustion cycle. For example, sticking a slightly bigger turbo on or turning up the boost a bit, increase the airflow but they maintains that basic rpm/airflow relationship.

Lastly, I always try and avoid jumping straight to installation errors, but it needs to be checked. For example, one tooth retarded inlet camshaft timing will give lousy mid range as the VVT will be operating out of range. The success of the 2 degree retard on the exhaust camshaft timing is interesting, I have found that 0 seems to be the best position in the Neo's.

Hopefully Bass there is something in the above that is of use:cheers:

[Bass Junky]

I felt a disturbance in the Force...........  

No hang on.

A disturbance in the Force I felt

That's more Yoda like isn't it?

I have never tried 260 degree Poncams with a standard turbo, we have used them with a GCG ball bearing hi flow and a GT30 on R34GTT's.  Made good power increases everywhere, particularly in the 4,000 rpm to 6,500 rpm range.   Even at the same or lower boost levels (less restriction, more airflow, lower boost).

So what's different about the standard turbo?

1. Maybe it's simply out of airflow, that would mean the same/similar power

2. What sort of power are we talking about here?

3. Did the boost drop?

4. Does it drop off at high rpm?

5. What do the A/F ratios look like?  Std cams Comparison?

Some things to try (maybe you already have)

A. More boost?  It may move the airflow into the cams' working range.

B. Less boost?  It may move the airflow into the turbo's working range

C. Advance the ignition timing?  If I remember rightly we had to advance the timing quite a bit on the Neo with the hi flow.  It didn't ping at the same timing as when it had the standard cams.

D. It also went a little rich on the A/F ratios when we changed the cams, so we had to lean it off a bit.  It was making more airflow (as per the AFM) but at lower RPM, so it needed some tuning at a number of load points.  Not as much change as the ignition timing though.

Changing cams requires a lot more tuning time than many other mods because it changes the fundamental relationship between the airflow, rpm and combustion cycle.  For example, sticking a slightly bigger turbo on or turning up the boost a bit, increase the airflow but they maintains that basic rpm/airflow relationship.

Lastly, I always try and avoid jumping straight to installation errors, but it needs to be checked.  For example, one tooth retarded inlet camshaft timing will give lousy mid range as the VVT will be operating out of range.   The success of the 2 degree retard on the exhaust camshaft timing is interesting, I have found that 0 seems to be the best position in the Neo's.

Hopefully Bass there is something in the above that is of use:cheers:

Okay, power we were making, 200 kW

Power now making, 200kW peak, but lower all the way through.

Boost, 11psi. Towards the top of the range, the boost drops 1psi, running powerFC boost control kit.

AFR, coming down to 12:1, had to add fuel in some places to stop pinging.

Using standard Turbs, I wasn't keen on turning it up.

Didn't think of using less boost.

With the cam gear, to be honest, we didn't try at 0 degrees (we were sick of adjusting it!!) but it was harder to stop pinging at 4, made truck loads less power at 2 degrees advanced and 2 degrees was easier to tune at.

Torque was just down everywhere....

Damn thing is going to make me high flow the turbo now.

Stupid cars.

It is shite on cold starts too, it will start okay, but as soon as I touch the throttle, it wont settle back down and hunts like a pig. I'll get that sorted how??

BASS OUT

[RS500]

who fitted/tuned the car with the cams?

[Bass Junky]

Speed Technology/EFI Hardware in Mitcham fitted them.

Craig (ex-Genesis) tuned it up on the F1 Performance dyno in Blackburn. Craig tuned my PowerFC about 6 months prior.

BASS OUT

[Bass Junky]

Just adjusted idle screw and shes all good now.

[Sydneykid]

Okay, power we were making, 200 kW

Power now making, 200kW peak, but lower all the way through.

Boost, 11psi.  Towards the top of the range, the boost drops 1psi, running powerFC boost control kit.

AFR, coming down to 12:1, had to add fuel in some places to stop pinging.

Using standard Turbs, I wasn't keen on turning it up.

Didn't think of using less boost.

With the cam gear, to be honest, we didn't try at 0 degrees (we were sick of adjusting it!!) but it was harder to stop pinging at 4, made truck loads less power at 2 degrees advanced and 2 degrees was easier to tune at.

Torque was just down everywhere....

Damn thing is going to make me high flow the turbo now.

Stupid cars.

It is shite on cold starts too, it will start okay, but as soon as I touch the throttle, it wont settle back down and hunts like a pig.  I'll get that sorted how??

BASS OUT

Some suggestions follow;

At 200rwkw there is bit left in the standard turbo but not a lot. I'd give it a quick run at 1 bar and see what happens.

Boost drop, so it's making 200 rwkw at 10 psi? That's pretty good, it usually takes 12 psi to make 200 rwkw. That means if you up it to 12 psi, it will drop to down 11 psi at high rpm.

Yep, the fuel map moves around a fair bit when you stick the cams in there. That's also the off idle problem, you need to tune it a bit richer than it was before for cold run. It will run closed loop when hot, so no problems there, as long as you have enough ignition timing in it.

Exhaust camshaft timing, I reckon 0 degrees is the go, based on what I have seen. I have never seen an engine that likes advanced exhaust camshaft timing, so I am not surpised it dropped a bucket load when you tried 2 degrees advanced.

As I said before, cams need lots more tuning changes than any other of the usual turbo mods. Don't let it get you down, you are not unique, one step backwards is sometimes required before you can take 2 steps forward.

Look on the upside, there is ~65 rwkw in a GCG ball bearing hi flow upgrade, now that you have the cams done.

[Bass Junky]

I'm dying for the 65kW now!!

[Bass Junky]

Okay, some driving impressions.

Sound:

Start up: Start's fine, no problems, Cold start idle problem now fixed.

Idle: A little bit angry when it's cold. Much sharper idle note. A bit deeper.

Driving: A little bit louder, not much, deeper.

Full throttle: A bit deeper I think, havent had a chance to oper her up at all to 100, but hey, these are public streets.

Power:

Off the line, same.

During gears, the car doesn't pick up as fast as previously. It used to get up on the boost mega quick which would lead to surging forward at low throttle inputs, but now more linear. The curve is now not so much of a curve as it is a straighter line.

Boost comes on a little later during overtaking type acceleration, but puch still very similar.

Other Stuff

First gear, still unusable. More to do with tyres I think than anything else.

Down a hill, foot off throttle, much quieter.... Also backing off the throttle after 50% throttle doesn't result in the little jerk forward that used to occur.

Doesn't burble down a hill if my foot is just on the throttle.

Less engine braking.

Dyno charts are to come probably over the next couple of days.

PS. Does anybody know if you can put your dyno runs from one dyno on a disk and then take your runs from another, put them on the disk and then compare graphs directly??

BASS OUT

[JAGR33]

Hey Pete,

might want to talk to Ben (Racepace), see if he's done any other rb25's with upgraded cams and standard turbo..... u never know!!!!

[Bass Junky]

Might do that.

[666DAN]

I hope you get that sorted, I'd be vomiting blood about now for that -10Kw per $2K!!!

Good luck with everything...I'm still thinking about buying your stock cams (if you don't want them still?)