B16a VTEC vs no VTEC power?

[Qwrx]

Does anyone have comparitive figures for the same rev range for a b16a when VTEC is working and when it is not working. Id like to know for a stock b16a(2) but any other setup the info would be welcome to.
I have done some searchin and cant find this info.


Thanks

[ZeForce]

If I remember correctly my old B16a made around 70kw on the low cam and 98kw with VTEC

[90LAN]

pull your vtec solenoid plug out and go for a drive

[Qwrx]

I have driven without VTEC working and know how it feels, but was more after some actual figures without having to go and get a dyno readout done. I figure that some people would have this info already

[FastFwd]

you just curious? or is there a reason behind you wanting to know?

[Qwrx]

A bit of both really. I had a wiring issue in my 92 civic rally car that stopped VTEC working, and was trying to get a better idea of how much power I was giving away to the other guys in the class. The problem has been fixed but still want to know.

Thanks

[FastFwd]

ahhh k k...yer if an of the main sensors are unplugged Vtec wont work.

I would say if its the audm model b16a then out of the 160hp it create's stock new you would be loosing at least 30-40hp.

And considering its a used motor then probably more.

[Limbo]

may need to do a dyno run, i've never heard anyone doing the non-vtec run and generally fixing it.

[dsp26]

i've seen one on a usdm motor.. prolly the same for aussie spec... i'll try find the dyno.

which is pretty dumb especially when people argue that honda engineers know best and vtec x-over is already at optimum position (at 5400rpm).

optimum crossover point is actually where the jdm p30 program is set at which is around 5875rpm (courtesy of ecu-man for providing it to me) which gainst up to ~5wkw between the original x-over to the new one... the transition is so smooth you don't 'feel the vtec kicked in yo' it feels linear which is what it's supposed to be.

but yes honda probably did that for safety/emissions purposes since jap has superior 100-104oct ron pump fuel.

but in terms of the 5400 x-over.. it dips exponentially after around 5900rpm (hence the jdm p30 better) whatever power you get on the dyno around 5900rpm is the limit of the motor on the small cam even if you x-over at 5400rpm.. so yeah, the 30-40hp loss is probably about right

[dsp26]

on a side note, this is where i argue that manufacturers, especially th elikes of honda, MAY know best.. but it doesn't mean they don't impose limitations on a vehicle for reasons such as emissions, longevity, fuel, etc.

this is why aftermarket parts are available such as cams, etc... they provide performance at the cost of emissions and drivability.. it does not mean the car is at it's full potential.

the ITR muffler is another rubbish oem product that's supposed to cater for a 147kw motor, there are dyno sheets out there or muffler change to a straight-through.... but i won't get into that debate. 350z for example... proven 20wkw gain from a full straight-through catback of slightly wider dimensions... or the xr6 turbo... and in the past we argued that catbacks and mufflers don't do shit.... depends on the car.

[Qwrx]

Thanks, Hope you can find that dyno sheet.
With the cross over point, optimal power and driveability would both have been taken into consideration from Honda. It all depends on what the final drive and gear ratios are and what they were trying to achieve with the particular car. Having a lower Vtec point costs a little bit of power but also makes it easier to stay on Vtec between gears (not so much of a problem with the right ratios). Honda would have taken all this plus noise and emitions into consideration when setting the cross over point. For the rally car, despite having close ratios I still choose a Vtec cross over of 4800 to cut in and 4500 to cut out. It may cost a fraction of a second initially but if i drop the revs coming into a corner then it makes it far easier to get power on the way out.

[dsp26]

^^^probably true.. but afaik i thought all honda's with b16a had the same ratios or final drives.

as for the x-over point, the simple fact is if the car makes more power linearly at a higher x-over point it doesn't matter if i miss 2nd cam band if shift earlier.

heres another example.. the difference with a 'chip that x-over'd at 5200rpm (spoon ebay chip vs the jdm p30-j02 rom i have):

spoon x-over'd at 5200rpm and jdm at 5875rpm.... because the spoon crossed earlier.. it FELT and sounded like it was going harder as they stupidly advertise it.. because the low cam was still making power then a sudden shift to the high at 5200rpm where the high cam actually made less power at that rpm than the low cam... because of this 'DIP' which was blatantly obvious on my own dyno sheets.. it gave the impression of the car going harder as the engine noise and power shifted.... for the worse.

not sure what your setup is but unless you have aftermarket cams.. no point switching the x-over point any lower than factory.. if anything you'd raise it. there are some people here that have aftermarket cams and no-one ever went backwards simply because most aftermarket cams with modified low cam specs still make more power than the high cam in mid rpm hence the raise x-over:
http://www.ozhonda.com/forum/showthread.php?t=91415

[Qwrx]

Youve raised a fair point there, I had been looking at things slightly different. It was mostly due to the cam/fuel mapping that i was using meant I hadnt wanted to even think about dropping out of Vtec. I am planning on putting together a more tailor made fuel map before the next event, so I will have a better idea of where im at after that. I was talking about all B-series ratios rather than just specific B16a in relation to the cross over point, however i am pretty sure there are different ratios for the cable clutch box to the hydro clutch.

[dsp26]

i'll post a dyno graph of both p30 and spoon tonight when i still only had i/h/e... i'm finding it hard to explain without the actual dyno so hopefully it helps.

gear ratios would make a difference but if it was a simple final drive change the powerband is retained as per engine output but the whole curve is shifted linearly to the left thus all power at all rpm bands previously now come on earlier.

[Qwrx]

I understand what you are getting at with the dip just after the cross over on the spoon map (also most other maps ive seen) Im running a close ratio box which ive added since the origional fuel map was setup for my car. If you could still post those dyno charts that would be awesome as any extra info is good info when tweaking things.

Thanks

[dsp26]

OK this is the dyno sheet of my internally stock motor at the time with only i/h/e and run in 3rd gear:

as you can see, the green line i drew is a rough simulation of what the low cam looks like but the blue lines depict the difference between 5200rpm and ~5900rpm


http://img.photobucket.com/albums/v281/dsp26/Dyno%20Sheets/DSC00035_modded.jpg


but then if you look at the red curve below which is the exact motor setup as above except with the jdm p30-j02 rom set at 5785rpm.. i gained power in the area depicted by the blue lines above... and as you can see, it's perfectly linear which is what it should've been from factory.

However the blue curve at the bottom is with the cams and higher compression (without new custom tune)... again theres a dip which means the new cams low cam profile still makes more power than the high cam past 5785rpm.. we found it to be in the vicinity of 6200rpm which is common for the BC3+ cams:
http://img.photobucket.com/albums/v281/dsp26/Dyno%20Sheets/B16a2_BC3plus_vs_Stock_modded.jpg


so to re-iterate my point earlier... it doesn't matter if you compensate for shifting too early before redline by lowering the vtec x-over... the amount of power you lose depends how far back before 5900rpm you set the crossover... there are NO gains... the only thing to gain is BOGGING after an early shift.. there is only one way to race a vtec engine and it is to redline it all the way to the limiter regardless if the power starts dipping 200rpm prior to the cut... at least you'll land back into the powerband.

[dsp26]

so for those with B16a motors and only I/H/E.. i am saying the jdm p30-j02 program is THE BEST off the shelf program for your ecu

[RtN]

so for those with B16a motors and only I/H/E.. i am saying the jdm p30-j02 program is THE BEST off the shelf program for your ecu

what's that out of? JDM B16a?

[dsp26]

what's that out of? JDM B16a?

guessing so.. but the only ones i've seen publicly for sale on eBay are the P30-J00 and P30-J01. duno whats different with the J02 but it was provided to me by a member on the forum.

the chip can't be used on it's own, to get the socketing kit from eBay or source the parts yourself from jaycar/Dick Smith:
http://www.ozhonda.com/forum/showthread.php?t=91844

[RtN]

hmm just read your link.. I guess it wont work with my OBD2

[Qwrx]

Thanks for the dyno sheets, I will be keeping this info in mind when I put together the fuel map for the next event.