rb25 lacks power

[bonestocksr20]

I recently finished my rb25 swap, and i used the rb20 5speed. I am wondering if the 25 transmission is geared different, because my car just seems to lack power. To put it into perspective my friend has a stock rb20 and he can pull away from me in my 25. The only mods on my engine are fmic, hks intake filter, 3" exhaust. Do you think that the fmic at only 7 lbs could affect my performance? The motor just seems very laggy and from what ive read a rb25 should spool quick as hell. Just installed boost gauge and there isnt any leaks and pulls ~25 lbs of vacume at idle. Any input would be very helpful

[Kansei240sx]

Running a bit rich would be my guess.

My RB25 was running like you say yours is, at the time i had, fmic, intake filter, full 3'' exhaust, and a greddy intake manifold, walbro 255 and the stock FPR i put down 225 rwhp at around 12 psi. I re-did the timing and advanced it 5 degrees and took out a 5 percent correction and dropped the boost to about 10 psi and made 272 rwhp at 11.1-3 afr's. Find a way to check your timing, set it, find a way to monitor your EGT's and AFR's via WIDEBAND 02 system ( zietronix, plx, techedge...etc.. ) or AEM uegos gauge.

Just a start.

[Cjmartz2k]

Wait, you've got -25psi of vacuum at idle? I'd love to know how your doing that.

I'd tell you to turn down the boost since everybody and their mom loves to crank up the boost to like 14psi with out tuning it, but it sounds like your not doing that. That will kill like 40hp btw.

[tek747]

Did you change out the plugs? That ended up being my issue.......might be a contributor to yours.

[bonestocksr20]

yeah i changed plugs for copper ngks gapped to .8mm like the fsm says. Timing is set a 15 degrees advanced. Im only running stock boost (7lbs) there is no smoke comming out of the exhaust so im not thinking it is running too rich but i have no wideband to know for sure. as for the 25 lbs of vacume at idle i dont know how i got that either but that is what my gauge reads.

[Yellow4g63]

yeah i changed plugs for copper ngks gapped to .8mm like the fsm says. Timing is set a 15 degrees advanced. Im only running stock boost (7lbs) there is no smoke comming out of the exhaust so im not thinking it is running too rich but i have no wideband to know for sure. as for the 25 lbs of vacume at idle i dont know how i got that either but that is what my gauge reads.

Did you check for any engine codes yet? Could be a bad CAS. Happened to a friend of mine he lost to a Integra GSR.

[bonestocksr20]

well i think i fixed it. i put on my rb20 wastegate actuator (10lbs) and it pulls like a mother******. only thing is now when i get to about 4500 rpms my motor stutters, i think i will pull the plugs install new ones gapped to .6-.7mm and put on my new coil packs (i think im just blowing the spark out)

[BoostFab]

put your gaps at 0.8 mm!!!! check for boost leak and 2x timing. hook a wideband on and see where you're running w/ your fuel mixture.

[bonestocksr20]

put your gaps at 0.8 mm!!!! check for boost leak and 2x timing. hook a wideband on and see where you're running w/ your fuel mixture.

i know the timing is spot on, as for the boost leak i am going to make a pressure tester to check all my vac/boost lines, but why should i leave the gap at .8mm?