Rb30/25 Struggling To Create Power

[stocko]

hey guys

the car is a r33 gtst

with a rb30/25 combo

engine was built buy hills motorsport

has

no vct solid cam

tomei pro cams 270duration 10.2 lift for inlet and exhaust

findaza adjustable cam gears

side entry plenum

mahl pistons

argo rods

acl race series bearings

n1 oil pump

standard harmonic balancer

rpm single plate ceramic clutch

3inch exhaust

tial wastgate

gt3540/ 82 r

power fc

740cc injectors

z32 airflow

eboost 2

car is getting tuned by 3 eleven motorsport tuner is shane brandon, currently worked for newcastle perfromance and unique auto sports

car will not make over 280kw no matter what boost pressure

1 problem,

thought to believe the car was polluting the charge? so after extensive hours and fiddling we put on adjustable camgears and found out that the timing was retarded.

fixed this issue dialed the cams in and still no significant power gains, then noticed problem 2

2.

boost pressure, turbo will create 20psi of boost but will not boost pressure. on the dyno graph. boost plot, the line drastically falls away at higher rpm, so we checked boost controller installation no problems

so then we disconected the conroller and ran it just with the wastgate, to find out it has a 7 psi spring,

so obivusly a stronger spring is needed?

problem number 3?

with the cams being 270 duration and 10.2 lift shouldnt it have a distintive idle? the car sounds like a boat, no crisp lumpy idle?

but on the short fall we cannot seem to get the figures you guys are creating.

an rb30/25 combo should be pushing around 320 350 kw at 25 psi?

any feed back would be great as my patience has worn particullary thin

Edited December 21, 2008 by stocko

[peter_fc]

what compression ratio are you running?

what size wastegate?

When the rb25 head is put on the rb30 block, compression drops unless the pistons are changed to compensate

Need more specifics on the engine.

Head gasket? what size? etc.

[brent32]

280rwkw doesnt sound too bad, seems to fit with results in the 'RB30 hybrid upgrade' thread for .82 housing 25/30s. Maybe some of the tuning guru's on SAU can help you.

Post up the dyno chart.

[stocko]

i dont know any or the specs,

bad bad experiances with engine build, not going into them over the net.

tiall 44mm gate, i think

cometic head gasket, thats all the specs i know

[Dale FZ1]

1. Look at the exhaust being overly restrictive (mufflers, cat)

2. Same for inlet/filter

3. Check to see your unions at all points between compressor and throttle are perfect. Where is the boost gauge feed being taken from? From the manifold, closest to the inlet valves is best because that accounts for losses through the entire inlet tract.

The unknown factor of compression ratio is a bit problematic because that will have significant bearing on what boost ceiling you should set.

The cam and turbo spec suggest you'd be chasing 500rwhp out of an engine that can hold power to 7500rpm, but no sign of porting, quality exhaust manifold (6boost style), crank balancing, or a quality harmonic balancer to deal with those revs and mass-flow throughputs. All components have to work together.

From the first post though, you should find 400rwhp an easy target to hit, so check the three suggestions.

Good luck and keep us informed.

[stocko]

1. Look at the exhaust being overly restrictive (mufflers, cat)

2. Same for inlet/filter

3. Check to see your unions at all points between compressor and throttle are perfect. Where is the boost gauge feed being taken from? From the manifold, closest to the inlet valves is best because that accounts for losses through the entire inlet tract.

The unknown factor of compression ratio is a bit problematic because that will have significant bearing on what boost ceiling you should set.

The cam and turbo spec suggest you'd be chasing 500rwhp out of an engine that can hold power to 7500rpm, but no sign of porting, quality exhaust manifold (6boost style), crank balancing, or a quality harmonic balancer to deal with those revs and mass-flow throughputs. All components have to work together.

From the first post though, you should find 400rwhp an easy target to hit, so check the three suggestions.

Good luck and keep us informed.

cheers well muffler is not restricted cat is missing the internals as was clogged, new item is waiting fittment

inlet/ filter is fine

boost guage is off the manifold 4 nipples for vacume lines

[Dale FZ1]

Boost falling away at the top end is normally a sign of rising backpressure, which is why I'd suggested the exhaust system as first area to check.

Is the muffler/s a proven thing? Easy to confirm your belief about them by dropping the system from just before the cat, and run on the dyno like that. If it makes the power then that would be where you spend money to fix it, otherwise it's cost you bugger all and given ideas where else to look.

Something that I've seen overlooked is whether people port match the T3 housing flange to the divided T3 stock manifold. Trying to force great quantity of air into the turbine past that 5-6mm lip is going to cause a lot of problems with efficiency.

If your tuner has the experience he would surely be looking at these obvious things anyway? What plan has he got to find the problem?

A couple of pics of your engine setup and current dyno sheets would be good..

Edited December 21, 2008 by Dale FZ1

[stocko]

Boost falling away at the top end is normally a sign of rising backpressure, which is why I'd suggested the exhaust system as first area to check.

Is the muffler/s a proven thing? Easy to confirm your belief about them by dropping the system from just before the cat, and run on the dyno like that. If it makes the power then that would be where you spend money to fix it, otherwise it's cost you bugger all and given ideas where else to look.

Something that I've seen overlooked is whether people port match the T3 housing flange to the divided T3 stock manifold. Trying to force great quantity of air into the turbine past that 5-6mm lip is going to cause a lot of problems with efficiency.

If your tuner has the experience he would surely be looking at these obvious things anyway? What plan has he got to find the problem?

A couple of pics of your engine setup and current dyno sheets would be good..

the exhuast has made 270kw with the rb and gtrs turbo

hes plan is to upgrade the wastegate spring, and that should settle the boost down,

but for the non lumpy idle i have no idea

[fatz]

um find a new tuner!

[Dale FZ1]

i dont know any or the specs,

bad bad experiances with engine build

I think this is one of the biggest hurdles. You need to know what the parts are, and that they are spec'd to work together.

Then the actual assembly of things has to be first rate. Things like matching the turbine to manifold are important and can't be overlooked if you want an engine to have a realistic chance of making the power its parts are spec'd to support.

the exhuast has made 270kw with the rb and gtrs turbo

hes plan is to upgrade the wastegate spring, and that should settle the boost down,

but for the non lumpy idle i have no idea

Big difference in flow requirements for 370 and 480rwhp if that's what you want to target. Can only suggest dropping the system to double check, especially if you potentially have a back pressure problem to chase.

If you want 20psi boost, then install a spring spec'd to 20psi. Make life simple, and use your controller to stop creep and bring the boost rise on sharper.

Are the comments about lumpy idle disappointment about the sound, or nagging concern that maybe the cams installed aren't what you believe them to be? That's a lot of lift to be having in a 25 head - was it machined to accept the cams?

um find a new tuner!

Maybe the tuner is producing the best results with the machinery presented?

[Al]

Dale has hit on a lot of good points, take note and complete the simple tests. Don't shoot down suggestions without trying them first, as you are the only one that will lose/gain from the results.

270kw from an rb25 is very different to 270kw on an rb30. With that turbo you should be making at least 330rwkw, so drop that exhaust and do another run on the dyno. You will also need to fit at least a 1bar spring in the waste gate, as a 7psi spring is way too soft and will allow the gases to escape prematurely.

[DCIEVE]

Assuming you have reasonable compression it 'should' be making around 400rwkw at 25psi...

I would be looking at base timing, a leak down test to check the valves are seating properly and a compression test will let you know if the comp ratio is in the ballpark. A low cr wont do you any favours.

Letting it breathe is the key as dalefz1 has said, imo these are a few things you should consider: a 3.5" exh making sure non of the mufflers step down (magnaflow race series etc), keeping the inlet pipe 4" without stepping down for an 80mm afm, and perhaps most importantly a quality merge collector type manifold.

[SirRacer]

my stock internal 8.5.1 compression .82 rb30 44tial (r32 25 head) made 310kws on a run in tune at 18psi.

your cams dont seem to be installed at all correctly? are you having spark issues also? whats happening with the afm voltage also?

[VB-]

got a graph? what valve springs are you using? any chance of float?

drop the exuahst off first coz its easiet, lose as much of it as you can.

you say power wont go up even if you crank the boost up, what happens to the A:F ratio when you wind it up?

comp+leak down tests

[NYTSKY]

Make sure the bolts on your cam gears are tight.

There was another thread like this before, after weeks of trial and error they found that those bolts came loose and timing was waaaay out.

And yes find another tuner.

[DYNAMITE]

Its the wastegate spring being 7psi, you need a 14.7 psi one or higher....

[darren lewis]

Its the wastegate spring being 7psi, you need a 14.7 psi one or higher....

wack up a dyno gragh for us will be able to assess it properly. yes stronger spring sounds like a try in the gate, also gate position??? thanks

[T04GTR]

what is your boost controller. if it cant make it make boost then id say youve reached the limmit for the turbine side of your turbo..

ps.. how did you get 270,10.25 cams in a rb25 head? i take it has some sort of solid lifter conversion? from the sounds of it the cam timing may be out.. but not 100kw out.

post up a graph.