Unsure On 25Det Results

[mawzy]

Hi all, so after a long twisted journey car has finally had a full tune and up and running. Just after some people more in the know what they think of power results, and the dyno printout. I'm a bit unsure about the power delivery over 4000rpm how its a bit up and down. I thought it should be smooth, and that this would be a tunning issue? ok so list of mods

Rebuilt 25det neo- arp rodbolts, metal shim headgasket, upgraded oil pump, heavier valve springs, new rings bearing etc, extended sump

Greddy style front face intake

660cc injectors

factory fuel rail

nismo regulator

nismo intank pump

greddy type r bov

3inch pipe to intercooler

Gtr style intercooler

3- 2.5-turbo intercooler pipework

Masterpower turbo .48 exhaust housing, .54 compressor (I think or .5)

sinco high rise manifold

turbo smart 40mm gate

full 3 inch exhaust, with venom 500 series cat, and adrenalinr high flow muffler

catch can, venting into intake pipe

4inch intake with k&N pod

the intention was to build a tidy responsive st package which I seem to have achieved. Tuning wise, the cam sensor was giving too sensitive reading at high rpm, so changed to a 24 tooth trigger wheel. But once fitted they only did 2 more power runs before pulling car off dyno. And the setup apparently reached it's peak at 16psi, and 432hp, saying the turbo was becoming a restriction or the exhaust. I'm confident the exhaust isn't the restriction, and knew the turbo was going to be the cars main limiting factor, but the supplier rated it to 20psi, and 450hp. So basically do you guys think numbers match the package, and are the dyno fluctuations a normal thing?

Link plug in ecu

[ARTZ]

.I'd think the restriction and the fluctuations are both caused by that gate and rear housing...its too small and choking on its own exhaust gases ,when they cant get out the exhaust fast enough they back up into the motor.,.you would want a .6+ rear housing at least..and possibly a bigger gate to match...i think its done pretty well to squeeze 432hp through it...you can put a bigger housing on it and easily get the same results response wise with more top end...

450hp rating would be an engine rating no doubt ...which it has acheived quite easily, i doubt they expected it to be on a 2.5lt motor..maybe a 1.8 or 2lt...

[hypergear]

By looking at the curve its not making much power for the setup or been responsive in todays standard.

Housings are tinny for this engine is, which makes compressor flow strongly relaying on the external gate. That would be making the turbine side red hot, probably starts to pin after a couple of dyno runs and it had to be pulled off the dyno.

It needs a much larger housings with more civilized wheel combinations.

[Super Drager]

Turbo has tiny housings on it, not suprised it became a restriction on a high revving 2.5L. I'd actually say that's a good result considering how small the housings are.

[mawzy]

THanks for input. Tuner didn't say anything about pinging, but wasn't making any more efficient power increases. This particular turbo does come with a .63 rear housing option, which I discussed with the seller at the time. He was good to deal with and seemed knowledgeable. He knew this was going on a 25det motor, and yes as stated probably correct, he would have been rating at motor which I hadn't thought about. Tuner recommended going to a garret turbo, which they claimed would push up to and a bit over 500hp.

Another much more cost effective option would be to change to the .63 exhaust housing with this turbo, and he said they're direct bolt in out options for the exhaust pipe. But do you think would be a worth while move, or is this not worth pushing any more? My original hope for setup was around 450-470 hp mark.

[ARTZ]

rear housing could see significant increases, this all depends on the rest of the turbo though....

do you have any more info on it?

[mawzy]

So going to turb specs from website,

compressor spec 54/77mm 49trim Forged CNC Aluminium,

centre housing MP350c, 360 Thrust, LI journals, Water cooled.

turbine spec 59/70mm 71trim 12Bld,

and finally the different ar options available T3 .48, .63, .7, .84, .94

Hope this makes sense to the technical savvy out there. Any opinions /thoughts appreciated

[ARTZ]

go the .7

[mawzy]

Does anyone have any insight into response changes with a .7 or .63 rear housing? like say really only looking for that extra 30-50hp, but don't want to compromise response too much either.

[ARTZ]

I think it will be fine either way....Neos have good head flow and run a bigger rear housing from factory than non neo RBs anyway...