hey i have a itr block with je 11,5;1 pistons and a b16 head with brower springs and jun 3 cams... an itr intake manifold and prelude vtec obd1 injectors... running a chipped p28 and vtec is set at 4500.... not sure if thats to low but the car ran well with a b16 with ctr pistons... and i just finished building this... the car runs well but when vtec kicks in it kinda boggs like it actually stops it instead of making it faster... what could it be? thanks

 

Its either lack of oil pressure, or fuel. Or lack there of. You said its a chipped P28.. chipped with what?

 

try raising vtec to 6000rpms. i have skunk2 stage 2's with 11.5:1 comp. and my vtec wouldnt even engage below 5700rpms-just start backfirin and stuff. i think it has to do with the size of the cams.

 

<TABLE WIDTH="90%" CELLSPACING=0 CELLPADDING=0 ALIGN=CENTER><TR><TD>Quote, originally posted by philafelman &raquo;</TD></TR><TR><TD CLASS="quote">try raising vtec to 6000rpms. i have skunk2 stage 2's with 11.5:1 comp. and my vtec wouldnt even engage below 5700rpms-just start backfirin and stuff. i think it has to do with the size of the cams.</TD></TR></TABLE>


yeah your problem is in where your Vtec engagement is set at. When i was running those cams, when i got the motor tunned mine was set at 6100

 

mines set at 5200 and its a perfect x over almost cant even see it on the chart....

 

what fuel injectors are u using ?

 

get it tuned...time for hondata, crome,. etc...

 

yeah i gotta get it tunned but for now ill raise my vtec engagement to about 6000.... any other pointers? im just running prelude 345 injectors i think they are... what do you guys think about those? should i throw the stock ones back on?

 

my stock compression b16 was doing that when i put sk2s2 in em..so we gave it more fuel and raised the crossover from 6k to 6400...runs perfect now...lol well kinda

 

Your bog is from the motor recovering from the VTEC x-over. I got this off of Rocket on another thread. Like everyone else said, raise the VTEC...you may want to get some tuning done as well. 345cc injectors? No tuning? Are you running rich? I would imagine too much fuel would cause a very nice bog as well.

 

you are using 345cc injectors u know what a friend was using the same **** & when vtec kicked in it would just fall on it's nose we changed the injectors to smaller ones & the problem was fixed

 

Honda type R and hamstr's points both make perfect sense because if vtec engages at too low an rpm, then you're giving yourself a lot more cam, but since you're rpms are low, your port velocity will also be low (due to less pressure differential between port and cylinder from lower speeds). You'll be getting a lot more fuel this way as with bigger injectors, but the low velocity will mean the air/fuel won't mix as well and you'll get a horribly inefficient burn, hence the bog. Correct me if my theory is skewed, just trying to recall from the massive r/s thread.

 

Seems like VTEC is engaging too low of an RPM for that manifold.

 

whoa 345's..dang, lol..yeah smaller... 310's maybe

 

<TABLE WIDTH="90%" CELLSPACING=0 CELLPADDING=0 ALIGN=CENTER><TR><TD>Quote, originally posted by veeetech &raquo;</TD></TR><TR><TD CLASS="quote">Honda type R and hamstr's points both make perfect sense because if vtec engages at too low an rpm, then you're giving yourself a lot more cam, but since you're rpms are low, your port velocity will also be low (due to less pressure differential between port and cylinder from lower speeds). You'll be getting a lot more fuel this way as with bigger injectors, but the low velocity will mean the air/fuel won't mix as well and you'll get a horribly inefficient burn, hence the bog. Correct me if my theory is skewed, just trying to recall from the massive r/s thread.</TD></TR></TABLE>

Correct. His oil pressure may just be barely enough to push the cams over, but without the proper swirl and port velocity, VTEC will fall flat on it's face. I would advise raising that VTEC x-over to at least 5700...if not higher. The manifold you have will make better power in the 6+ range. Below that, it will not have the appropriate funneling effect for your low VTEC engagement point.

 

<TABLE WIDTH="90%" CELLSPACING=0 CELLPADDING=0 ALIGN=CENTER><TR><TD>Quote, originally posted by HONDA_TYPE_R &raquo;</TD></TR><TR><TD CLASS="quote">

Correct. His oil pressure may just be barely enough to push the cams over,</TD></TR></TABLE>

I guess I'm not sure what you mean by oil pressure pushing the cams over, are you referring to the vtec solenoid? Please clarify if you could.

 

Yes, the solenoid. It uses oil pressure to push the cams over. I am sure someone on here could explain it better than I.

 

Yeah I'm kinda confused. I thought all the solenoid did was actuated the piston that pushes the pin to connect the valve lifters. I'm not sure how oil pressure "pushes the cams over". I just thought that the cams were turned over in relation to cam gears, timing belt, crankshaft etc. I must be missing something. I would greatly appreciate if someone could explain it to me.

 

<TABLE WIDTH="90%" CELLSPACING=0 CELLPADDING=0 ALIGN=CENTER><TR><TD>Quote, originally posted by HONDA_TYPE_R &raquo;</TD></TR><TR><TD CLASS="quote">Your bog is from the motor recovering from the VTEC x-over. I got this off of Rocket on another thread. Like everyone else said, raise the VTEC...you may want to get some tuning done as well. 345cc injectors? No tuning? Are you running rich? I would imagine too much fuel would cause a very nice bog as well. </TD></TR></TABLE>

That's funny. You make it sound like VTEC some major orgasm or something.

 

<TABLE WIDTH="90%" CELLSPACING=0 CELLPADDING=0 ALIGN=CENTER><TR><TD>Quote, originally posted by veeetech &raquo;</TD></TR><TR><TD CLASS="quote">Yeah I'm kinda confused. I thought all the solenoid did was actuated the piston that pushes the pin to connect the valve lifters. I'm not sure how oil pressure "pushes the cams over". I just thought that the cams were turned over in relation to cam gears, timing belt, crankshaft etc. I must be missing something. I would greatly appreciate if someone could explain it to me. </TD></TR></TABLE>

...rock head! I explained it the wrong way. What you said is correct, I goofed up on my explanation.

<TABLE WIDTH="90%" CELLSPACING=0 CELLPADDING=0 ALIGN=CENTER><TR><TD>Quote, originally posted by cpforyou &raquo;</TD></TR><TR><TD CLASS="quote">

That's funny. You make it sound like VTEC some major orgasm or something. </TD></TR></TABLE>

You have a dirty mind...LOL!

 

Thanks for clarifying, it happens to the best.

<TABLE WIDTH="90%" CELLSPACING=0 CELLPADDING=0 ALIGN=CENTER><TR><TD>Quote, originally posted by cpforyou &raquo;</TD></TR><TR><TD CLASS="quote">

That's funny. You make it sound like VTEC some major orgasm or something. </TD></TR></TABLE>

Oh Yess!! VTEC is just that damn good! LOL