Rb25 Poncam Issue = Missing 80kws

[dangerman4]

Hey guys

Happy new year to all

before chrisy i installed my poncams and got a tune expecting a nice fat midrange with a strong top end as the cams are designed to do. yet i was missing 50 kws from my previous tune with the standard cams.

we got the pfc boost kit working well with a fairly constant 24 psi, but the dam thing just wouldnt make any power.

i dont have a printout of the run, but it was making slightly more power down low then up past 4500 the old graph left it for dead.

previous graph with gizzmo boost controller was 317 kws

new tune with poncams and pfc ebc is around 270 kws

gizmo tune was 26psi droping to 24 psi at redline

pfc ebc was constant 24 psi to redline

also the power was dropping off slightly past 7k whle with the standard cams it was still pulling hard at 7300

"ITS NOT THE CAM TIMING"

i have checked, spun the motor and re checked.

Just a thought.

What have i changed between the old cam tune and the new tune?

Poncams

new 4 inch stainless intake from q45 to turbo

PFC ebc

Full Auto trans build by MV auto with a 3k high stall.

So i wonder what difference the built trans is having on the dyno?

Whos got a crystal ball thats works?

Cheers

Darren

[DVS JEZ]

maybe the tuner hasnt changed the maps enough?

is the comp setup for the q45?

what is the airfuel doing on the graph where it dies down to 270kw?

[2rismo]

Did you change the converter?

[dangerman4]

maybe the tuner hasnt changed the maps enough?

is the comp setup for the q45?

what is the airfuel doing on the graph where it dies down to 270kw?

Old tune had the q45 on it, i have just changed from a 4 inch silicone elbow to a 4 inch stainless elbow.

AFR over 4k its 12 dropping down to 11.5 at 7300rpm

[dangerman4]

old tune was with the stock convertor

new tune was with the 3k high stall

its the standard converter that they have gutted and replaced all the internals.

[seeyagtr]

Have you installed you cams with cam wheels??

I have had a couple of pon cams that need a fair bit of adjustment to get any top end out of them?

At the same time my cam when in with only 4 degres on the exhust cam

Cam wheels might be the answer

[dead32]

what size cams? did u change valve springs etc also? maybe to much overlap causeing them to valve bounce? just a thought,

[RellikZephyr]

dont high stall cons rob a little power due to the way they work?? or something like that

RellikZephyr

[dangerman4]

has anyone had there inlet cam slip on the the vct?

could this be a problem?

[StockyMcStock]

post up both the dyno graphs man, it will help.

could be valve bounce, or incorrect cam timing. did you check it with a dial guage and degree plate?

[dangerman4]

no i havent used a dial gauge, just set them both at zero.

i had the head apart when i did my full rebuild and all the standard springs where measured and were all in top nick. as the car from new hasnt done 50k yet.

so i was thinking it wasnt the springs as the cams are designed for the standard valve train.

[Adriano]

From what i have seen, high stalls dont work well with dyno's, dynod many cars with them, and they never seem to make the power they should. I dynod an XD recently which made heaps of noise, and only 260 rwkw, but that night ran an 11? Does the car feel noticeably slower in the top end? 80kw should be very noticable in the seat of the pants dyno?Should make more power down low, as thats the torque multiplication doing its job.

[Busky2k]

Same dyno yeah?

[dangerman4]

Same dyno yeah?

yea same dyno

we overlapped the old tune and the new one but i didnt get a copy of it.

new tune started off better then crossed the old tune about 4k ish then followed it up to redline but slowly lacking more and more power.

old tune with standard cams

[rev210]

The cams 'will' require adjustment and when you do adjust them you need to alter timing and fuel maps to suit. The timing map you had of the stock cams will not work well at all for example if applied to the new ones.

You 'must' invest in adjustable cam gears if you have not already, at least on the exhaust side.

The cams will increase the engines airflow capacity without question if setup correctly, that is the good news.

[dangerman4]

The cams 'will' require adjustment and when you do adjust them you need to alter timing and fuel maps to suit. The timing map you had of the stock cams will not work well at all for example if applied to the new ones.

You 'must' invest in adjustable cam gears if you have not already, at least on the exhaust side.

The cams will increase the engines airflow capacity without question if setup correctly, that is the good news.

SK reckon's they are best set at standard?

but having adjutment will be handy so i will aquire one.

"The cams will increase the engines airflow capacity without question if setup correctly,

that is the good news"

was there bad news coming?

[meatwagon]

pop the auto out and tune it with a standard converter, big converters hate dynos, if u tune it with the stock item in then pull box out and put bigger one back in you should find its all sweet, but yes you should dial them in correctly too

[rev210]

I think if you ask SK, he's going to tell you the same thing. His comment reffered to a particular cars setup ,one totally different to yours. It was a Neo motor for a start. Even if I owned a neo engine I certainly wouldn't assume that 0 and 0 are right for an application where turbo selection and high stalls are involved. Engine loads on the new stall will play a part in changing the game.

Always explore cam timing changes no matter what engine, you can do so much to the power delivery by altering it.

Having said that if you didn't alter the timing map significantly for the new cams then there is no question you have a massive issue right there. It is critical to good power with the larger duration,lift and overlap cams you have especially up top in the rpm.

My guess is you are going to end up with quite a bit of adjustment on the cam timing given the airflow target is above 300rwkw.

I'd expect to see as much as 100hp+ peak power or so improvement over the stock units at the same boost once they are setup right.

[Cubes]

Darren,

The converter aside how smooth is the top end of the graph?

Nice and smooth? I've noticed as valve float occurs that's not really noticeable (i.e pumping up lifters or massive nose overs) the graph tends to start to wobble up and down slightly away from the usual smooth curve and as you dial in more boost power doesn't pick up as it should.

The valve springs may appear in top shape but for the boost you are running they will be nearing the limit.

Some with rb25 heads begin to float at around 20psi others have no issues up to 25psi. It 'may' be possible the cams have a slightly more aggressive ramp rate that pushes the springs just over the edge *slightly*. Enough so that it just won't make any more power even if you dial more boost in.

Pushing more and more boost in will have power nose over hard and it will pump the lifters up.

Its going to be a pain in the arse to diagnose as it a few changes have been done at once.

Hows it go if you dial in less boost? Big power drops or?

270rwkw through an auto.. I'd expect that to be done on around 17-18psi behind an auto.

[tridentt150v]

I think 32's you have to dial in some degrees, R33's are best on std, R34's I don't know thats on a gtst, gtrs are different again..

My R33 is on 0 degree's and works fine. It was originally set at -4 degrees and I lost 30rwkw, reset to 0 and found them again.