last year i put a drag gen III turbo kit on my car and tuned it with hondata s200 and RC440cc injectors..

this year i built the bottom end..sleeves..pistons 9:1...eagle rods..walbro 250lpg fuel pump and im in the process of breaking in the motor and im in the process of breaking the motor in..ive got about 250 miles so far and i havent reved past 3500 rpms, im startin to rev alittle higher and it seems like my car is running lean when i get to like 4k..the car kinda sputters for a 1/2 second like the fuel got cut off or something..its not that noticeable but i can feel it. i got a tial wastegate and im runnin like 5psi(never hit boost) ive got an air fuel ratio gauge and its on the lean side when i get to like 4k rpms. im kinda scared to rev to like 5k if its runnin really lean... y is my car sputtering?? any suggestions? should i just not rev past 4k until i get it tuned(gonna break the motor in for about 1000 miles)? thanks

 

my car..1999 civic si

 

i would suggest getting it tuned, as you have changed alot of things from last year and you need to be retuned.

 

I had the same setup as you, hondata-tuned B18C with drag 3 kit and 440s. I had the block rebuilt with 84mm 9:1 pistons and broke it in on the existing tune. Mine also ran slightly lean just as it started to come into boost, tho I could take it to 5k if I accelerated gently. I guess the setup is different enough to affect afr's. I did 700 miles without boost and not going over 5k rpm, then got it tuned again. If you know its running lean, don't risk it, take it steady!

 

yea im gonna just take it steady.....just not gonnna go over 5k for now, will the motor be brokin in if i dont take it past 5k and then get it tuned?

 

Thats how I broke mine in, just varied the rpms as much as possible and took it slowly up to 5k a few times, especially in the first 100 miles. Mine's been fine since (apart from my recent post about overheating, ignore that )

 

yea i changed my oil at 50 miles and now proly gonna do it again soon then at 500 then at 1000. .. im very confident my motor was put together right and good parts were used. so yea hope i dont fuckit up