a friend of mine is having a problem after installing JUN cams in his itr setup. Right at vtec engagement his car bogs, from 5600- 6000 (vtec at 5700). after 6k, it pulls as expected.. but in this range, its almost liking hitting the rev limiter...

can anyone explain the bog?
any ideas are greatly appreciated!!!

 

one of my freinds had the same exact prob w/ his car it had the jun stage 3 cams, it would bog when he hit vtec. i think he fixed it by swapping his ecu for a type r ecu, oh yeah his car was a 2000 gsr. he also had a vafc that didn't seem to help that much but it did a lil. actually he is dumping the jun cams and going back to stock they just didn't seem to perform. maybe they would be good in a fully built high compression motor with a very ported head but on his stock gsr they just didn't work that well.

 

I think what you seeing is that some of those cams (if not all cams really)..Especially the agressive ones like Jun need to be tuned. Most of these cams really dont keep their stock Vtec Settings or rev limit. You might need to Adjust cam gear settings, Dial in the Fuel, switch the Vtec Crossover, and all that jazz. My .02 cents


[Modified by Shinmantis, 2:39 PM 8/9/2001]

 

hhmmmm, ok. well, he is using a p73 or p28 ecu - which is why vtec is at 5700 (5800?). so, there is no interference from a vafc or anything...

jun, and my experience says that cam gear settings shouldnt create a bog only during vtec crossover. if there was a lot of hesitation throughout a section of the rpm range, then i would agree, but only for 200-300 rpm? doesnt make sense to me.. ive seen it happen where vtec is engaging on stock gsr settings with these agressive cams, itll bog for 2000 rpm or so, but this is a itr setup, with higher vtec engagement.

i think the cam install was just coincidental with the vtec solenoid or perhaps tps or something failing at the same time.. this is what i was wondering.. any guidance in this direction?

thanks for the tips tho...

 

my freind called jun several times and tuned the cam gears exactly the way jun told him and the car still bogged not as bad but still not good. the only thing he has not done is put the car on the dyno and tuned it that way, overall he is just not happy with the cams. i know for a fact that his car was much quicker with his stock cams. maybe it just felt fasted than w/ the juns cuz the juns seem to make power way up in the rev range

 

Here is what the problem(s) could be... Cat needs to be 2.5 inches. Fuel pressure at least38-42 psi with the line on. These cams are hard to tune, the only anser to the solution is a JUN ECU. It has everything to do with fuel and ignition curve. Unfortunatley no one has the pirated JUN chip. At least not an offical chip. The ECUs are 1800.00. Your best bet is to get a cuatom ECU by yoshio, I heard his ECUs are almost right on the money. Dont forget also. 11:1 compression is really needed with those cams. JUN will never tell u the truth about the cams, they want you to fork over $$$$ for the ecu and pistons. All u need are they JDM ITR/CTR pistons and youll be set. Ive had these cams for 3 months, itune then better each day

 

u need dynotune and a chipped ecu and a vtec controll,er headers, pistons, blah blah

the same **** happened to my car wit da crower 63403 race cams. there was like no power from vtec crossover til bout 6500. then it pulled like a bitch. those cams need supertuning, and a very high redline to make the power they're supposed to.

 

i talked to my freind, and he said that jun told him that the bog was caused by the cat being too small and not enough fuel. his words not mine. also it seems like most people that i have talked too with the jun stage 3's have built motors with high compression.

 

Here is a dyno curve of a 2000 Type R with June Cams with the problem you describe. http://Hondata.com/dyno00typer.html It also shows the very good results you get from ecu tuning. 12 peak HP gain and torque gains all the way from 4000 RPM to 9100 rpm.

The problems were fixed by raising the VTEC point to 5900 rpm and paying particular attention to fuelling around the VTEC point.

Total cost for this 2000 Type R customer was $800 for the conversion to an OBD I system including the Hondata Stage 2 option and several hours dyno tuning. AEBS San Diego have this program if anyone is interested.


Doug

 

Hi,

This happens to me too if I enter a corner out of VTEC. Something to do with the pin not moving out of the way. I fixed this problemo by entering corners a little hotter, so there was no engagement issues. It was doing this religiously in Turn 5 at LSIR. It only bogged on me like you explained on corner exit, when the revs came back up to 5700. I also noticed that being smoother on the gas after corner exit (if I entered out of VTEC), rather than just punching it just before the apex also helped a lot. I have not experienced the problem since.

Peace...

 

Doug, why is it so hard to fine tune these cams. I am very interested in that hondata setup. I have a 2001 GSR with all the bolt ons and JUN III topend. I switched to a 2000 Type R ecu to take adavantage of the extra revs. I am in the process of having JDM ITR pistons installed. My question is this, what was the fuel pressure at during the dyno?