So what's the deal with this, is my turbine wheel too small? I have a t3/t4 with an ar of .48 on the turbine and a .6 on the compressor. When VTEC hits it feels pretty bad and almost like it's reached its limit. Anyway, I"m running a JRSC fmu which is like a 5:1 but I've tapped it into the intake manifold so I'll get an extra 5 -10 psi of fuel pressure depending on my IC drop and it's running full rich. I'm just wondering why it feels so flat when VTEC comes on as well as why it sometimes stutters and sputters when giving it full throttle.

 

what kind of fuel pump are u running? do you have a inline pump with the fmu?

 

Yup, it's a bosch inline.

 

too much fuel.
jrsc fmu's are really bad for crapping out aswell


[Modified by SiRkid, 11:20 PM 3/30/2003]

 

Too rich. I had the same probelm with my setup when i first put the new turbo on.
Once vtec hit the power would stop.
The ecu dumps more fuel once vtec hits so once it switches over your overly rich. I'm also going to bet that your probably to rich throughout the power band.
my experience
8:1 fmu it would pull hard until vtec then it stopped accerating(felt like it was bouncing off the rev limiter
6:1 fmu it would pull hard up to redline felt pretty good. (air/fuel ratio of 10.0 or richer)
4:1 fmu pulles harder and air/fuel ratio of 11.0- 11.5 (before i leaned it out even more with a sfc)
with the 6:1 fmu i made 199whp
4:1 fmu i made 217whp then another 9hp with the fine tuning of the sfc (leaned it out more

 

your turbo might be the limiting factor as well... w/ such a small turbine housing and so much air being consumed by the vtec head, its not that hard to figure out where the problem lies.. could be ur fueling too..

 

could be, but if the turbo was to small boost would just drop off in the top end vs causing a problem like this.
I ran a smaller turbo (t3 .42 trim) on my b16a and boost would drop off above 5k rpm because it was too small and couldnt flow enough.
anything is possible but a .48 shouldn't be to small (smaller then what i would run)


[Modified by b16ahybrid, 4:54 PM 3/30/2003]

 

Well, I changed the boost source back to what I had it and instead of running a boost line from the charge piping before the intercooler, I have now tapped it into a boost source from the intake manifold. It's a bit better but it it is still a bit rich I guess cuz it's still a little wonky.

One question I have is spark plugs as well as oil in the charge pipes. The turbo I had before took a huge dump and there was a **** load of oil in the charge piping and compressor housing. We've replaced the center cartridge but there is still some oil in the charge piping and probably intercooler. The good news is that it's not in the new turbo but there is still some coming out the bov. Could the excess oil that is making it to my plugs and combustioin chamber be causing this fall in hp in addition with the extra rich fueling?

Also, so is it the general consesus that I should decrease my rise rate? I can get access to an adjustable holley one which is from 1:1 and goes up to 4:1 rise rate.

 

Just one other thing...why is that so many people need to run 12:1 or 10:1 fmus and I'm running too rich with a 5:1? Is it because my injectors are that much bigger? I've heard that they are anywhere from 310's to 345's but in any case, why would I be running too rich with a 5:1?

 

What injectors were u using with the 4:1 fmu and what fmu? the vortech?

 

I figured that it is the turbine too, I was running the same size on my integra with the hack and I was getting a similar problem, I had to shift gears around 6k


[Modified by legendboy, 8:04 PM 3/30/2003]

 

So you think it's entirely the turbine wheel being too small or do you think it has something to do with it being too rich?

 

NO.
its not your turbo.
id say its a fuel problem!
get rid of that jackson pos.

 

310cc rc injectors.
Most people run a 8:1 vortec fmu with 310cc injectors just fine.
I was skeptical about runing even the 6:1 fmu but i tried it and it helped. I eventually ended up with the 4:1 because the 6:1 was still to rich. I know this for a fact because my car has been tuned on a dyno with a wide band o2 sensor so i know my air/fuel ratio readings are accurate.

 

so are you saying get rid of just the jrsc fmu or ditch the fmu entirely? I know that I should be going with a standalone but for now, the fmu will have to do...with this in mind, do you recommend going with a smaller rise rate?

 

Oh yah, one other thing, I'm currently running stock plugs with stock gap...do you guys think this will have a huge bearing on why my setup is running the way it is?

 

shorten the gap. you have mail

 

Other things that I'm wondering are firstly, could my inline fuel pump be causing me to go over rich? Would there be any benefit for me to take out my inline and just run my stock fuel pump with the jrsc fmu?
Secondly, if it is the vtec that is causing too much fuel, would there be an upside to turning off vtec and if so, how can I simply turn off vtec? Is there a wire I can make a switch for or something?

 

Ditto that. I was having the same problem before I got my hondata. When vtec would kick it it would bog for about 600 rpm and then it would start to build power very quickly.