Was 240, Now 225 With Cams?

[tridentt150v]

Ok,

I've got a R33 gtst that was making 240 rwkw, put in tomei poncams [256/8.5] and now its only making 225?

Only other change I've made is swapping my HKS mushroom air filter element [two layer wet] for a three layer dry unit.

Set up on the dyno we couldn't get full or stable boost, peaking at 17psi and falling away to 10-12psi.

Injectors are at only 60%, so plenty of room left there.

If I keep going like this, I'll have to install peddles just to get the car moving..............lol.

I reset the evc the next day, and then gave it a run up a steep-ish hill, boost peaked out at 1 bar=14.7psi.

Stock boost was 0.59, so set it at 0.80 and then high boost at 1.2 with a 100% gain and 0.2 scramble boost for 10 seconds.

So what can make the car do this inside a couple of months??? Everything seems to be working OK, turbo, wastegate etc.

Mods affecting engine performance are:

HKS pod filter

Z32 AFM

Bigger injectors (yellow top colour coded)

Blitz 700x600x70 fmic (anodised blue)

HKS IV evc

Blitz turbo timer

Apexi turbo boost gauge

Greddy gauges x3:oil pressure, oil temp, exhaust temp, mounted in a dash pod

Apexi hiflo cat with full turbo back 90mm exhaust

HKS Viper 120mm s/s muffler

GCG converted Hiflow turbo [From 51.2/71mm to 56.3/76mm]

Walpro 500hp fuel pump

Tomei adjustable exhaust cam pulley

Power FC + HC

[Al]

Is the adj. exhaust cam set to 0deg?

Did you dyno it on the same dyno?

240rwkw with hi-flow and std cams sounds high , maybe the figure is more accurate now. Does the car feel slower?

Also: You stated that you had a HKS mushroom filter, have you checked the compressor wheel of the turbo. Those filters aren't the best and tend to allow shit into the turbo. If the wheel is slightly damaged, this will have an affect on performance.

[tridentt150v]

Same dyno, same software, I think the exhaust cam is at 4 degrees.

Timing is at 15 and then rising to 40 at revs, can't remember what revs, but I think about 3000 or there abouts.

I can double check both these figures if it helps.

Haven't checked the turbo, but I'd be surprised if it was the cause. When I drove it in it felt like a real 240 [it felt strong and torquey], after getting the cams fitted I lost power, both midrange and peak and you could feel it easy [won't 'bag up' in 2nd gear, won't pull hard when going up a steep hill etc]

I was expecting around 250-270 rwkw, GCG reckon the turbo is good for 400hp=300kw, but I wasn't aiming that high. Wanted to keep my midrange, wasn't looking for peaky top end power.

[Bl4cK32]

those cams apparently run best when set to 0deg. ie they are setup out of the box. Did u start at 0, and work your way to 4 deg? or just slap it straight to 4?

[tridentt150v]

Nah, the mechanic that I was using as my 'coach' set the timing of the cams from his previous experience with them. His experience is mainly with GTR's [from talking to him while I was working on the car]. I gather that he has done GTST's before, but not as often.

I've had the car for 3 years, slowly building it up with add ons etc, I do most of the work on it, but when I have to tackle something I'm unfamiliar with I get my mechanic to do it and I help and learn. I've done heaps of mechanical work before, but mainly motorcycles [top end, bottom end, modifications, big bore kits, custom frames and wiring looms, welding, polishing, sandblasting, you name it]. I gotta say that I'm still learning with my Skyline, but I like the 'Built not bought' motto, so hope to do my own stuff as I go.

[Bl4cK32]

See SK's comments - http://www.skylinesaustralia.com/forums/in...c=98247&hl=

[AlexCim]

turbos are rated at the fly wheel, not at the wheels.

a 450hp turbo will max out at ~250rwkw, which is what the GCG does.

[rob82]

Are you sure the cams are in the right position and did you recheck the base timing after you moved/degreed the cams in?

[tridentt150v]

Cams are definitely in the correct position, I checked. The timing was checked and all was fine.

Bl4ck32, thanks for the thread, good value.

I reckon [well it looks like] the ex cam should be at 0 rather than 4 degrees. Thats a good starting point anyway.

[Cubes]

Out of curiosity.... Are you able to take note of how the cams have affected fuel economy if at all.

[tridentt150v]

Out of curiosity.... Are you able to take note of how the cams have affected fuel economy if at all.

Hope not to have the problem that long Cubes. But as an aside, in the 200km I've driven with it I reckon the fuel economy is marginally better [more subjective than objective]. But I have to qualfy that statement with:

The car is not making as much power ie less fuel/air is used.

I am a bit p1ssed off/dejected about the whole thing and so am not driving it as hard [loss of faith].

I am trying to be more conservative in my driving style and not f#ck anything in the motor until the problem is fixed and the engine management is tuned correctly.

[T04GTR]

it has been tuned propery hasnt it?

[tridentt150v]

Yes, but only in a 'best we can do' way until I find out where my power has gone. Had it on the dyno and used datalogit to get it as good as we could given the problems.

[Cubes]

How does the power curve compare? Post a dyno sheet.

[tridentt150v]

How does the power curve compare? Post a dyno sheet.

Sorry, so disappointed [that it wasn't a clean add on] that I told him I didn't want it. It'd only be a beer coaster to me. It was making less power all round than the 240 graph, from memory approx 20 kw less in the low midrange and 30 in the top midrange. A/F ratio was also not very pretty, it was a jagged line with heaps of flickering. No smoothness in it.

I'll see if I can get a printout of it sent to me [i'm a couple 100 km away from the dyno place], joys of country life!!!

[Miss Turbo]

it sounds like you have or someone has not hooked up some6thing properly, check ll thye vac/boost control hoses. and plumbing.

im sure you wouldnt of got the timing belt wrong.

[R31Nismoid]

Nah, the mechanic that I was using as my 'coach' set the timing of the cams from his previous experience with them. His experience is mainly with GTR's [from talking to him while I was working on the car]. I gather that he has done GTST's before, but not as often.

An RB26 is not an RB25

Just because one setting works with the RB26, doesnt mean it will also work with the RB25

I think thats, as everyone else has said, where the problem is. Set the gear to neutral first... only then adjust it either way.

Starting on -4 or +4 isnt right

[satanic]

GCG highflow maxxing out at 250rwkw ehh? Are you sure on this claim?

Abo Bob is running one and he's pushing (well was) 255rwkw on 0.9bar of boost + Tomei Type B 260degree Poncams. I really doubt that the turbo had run out of puff by then.

[tridentt150v]

An RB26 is not an RB25

Just because one setting works with the RB26, doesnt mean it will also work with the RB25

I think thats, as everyone else has said, where the problem is. Set the gear to neutral first... only then adjust it either way.

Starting on -4 or +4 isnt right

Including me!!! But only after coming back and reading up on the topic on SAU.

"I didn't know yesterday that which I now know today".

[R31Nismoid]

"I didn't know yesterday that which I now know today".