v-tec kickin when?

[K-V-NO]

just installed ctr cams in b16, v-tec now kickin @ 4800rpm, should i have the ecu chip and have v-tec kickin later. any suggestions?

 

[sohcslammer]

No.

 

[xj0hnx]

Changing your cams won't change your crossover point.

 

[sohcslammer]

Originally posted by 92b16vx@Aug 26 2003, 04:52 PM
Changing your cams won't change your crossover point.

I started to type that too and realized he just worded it fucked up. He is asking if he should chip his ECU to cross it over l8r. I'm not sure what a B16's stock X-over is so I figured it was @ 4800. That seems a little low now though.

 

[cycloneb18c3]

what ecu are you using? 4800 sounds like a SOHC, a spoon chipped ecu, or that ur using a vtec controller. I dont think any stock honda program kicks the vtec at 4800 for a dohc.

 

[GSRCRXsi]

Originally posted by cycloneb18c3@Aug 28 2003, 08:58 AM
what ecu are you using? 4800 sounds like a SOHC, a spoon chipped ecu, or that ur using a vtec controller. I dont think any stock honda program kicks the vtec at 4800 for a dohc.

i dont know ecu specs or anything but i wouldnt doubt that vtec could kick in at 4800 stock. hell my b18c hits vtec at 4400. and yes thats the stock crossover point with the stock obd1 p72 ecu.

 

[K-V-NO]

Originally posted by cycloneb18c3@Aug 28 2003, 01:58 PM
what ecu are you using? 4800 sounds like a SOHC, a spoon chipped ecu, or that ur using a vtec controller. I dont think any stock honda program kicks the vtec at 4800 for a dohc.

the stock b16 ecu is being used, seems like its kickin a little too early, no, should it be set to kickin later. someone mention to chip ecu and have v-tec set @ 8000rpm and get a v-tec controller to set my v-tec.

 

[xj0hnx]

Setting your vtec at 8000 is also usless, unless you have cams and a valve train that can rev higher than that and make power. The P30 is 5500 I believe, or 5800, but you probably have a PR3? I think the cross over on those is a little lower.

 

[CRXRookie]

Wow, whoever told you to set the vtec at 8000 rpm is a complete moron.

 

[90crxb16a]

i have a pr3 on my b16 and my Vtec kicks in at 5500 rpm's

 

[K-V-NO]

Originally posted by 90crxb16a@Aug 28 2003, 03:54 PM
i have a pr3 on my b16 and my Vtec kicks in at 5500 rpm's

mine's a pr3, v-tec was kickin @ 5500, since installin the ctr cams it's @ 4800

 

[xj0hnx]

Originally posted by 90crxb16a@Aug 28 2003, 04:54 PM
i have a pr3 on my b16 and my Vtec kicks in at 5500 rpm's

There you go.

 

[khai_tuan_nguyen]

What is a Pr3-3 on a head? 99-00 civic si?

 

[xj0hnx]

Originally posted by khai_tuan_nguyen@Aug 28 2003, 06:45 PM
What is a Pr3-3 on a head? 99-00 civic si?

B16A casting code, it is also on the block underneath on the driverside

 

[Bl6CRX]

Yeah, im not sure if id have it that low, more like 5200-5500 sounds better but besides that it would be fun to have VTEC kick in at 8 (i know its a stupid idead for performance) but when we were bored one day and started messing with my bros VAFC and made it kick in at 6500ish the cross over is intense, pulls so hard

 

[seanjuan]

Originally posted by Bl6CRX@Aug 28 2003, 03:02 PM
Yeah, im not sure if id have it that low, more like 5200-5500 sounds better but besides that it would be fun to have VTEC kick in at 8 (i know its a stupid idead for performance) but when we were bored one day and started messing with my bros VAFC and made it kick in at 6500ish the cross over is intense, pulls so hard

Vtec crossover shouldn't be "intense", if tuned properly it should be a continuos power gain with no drastic spikes

it is my understanding that you should not "feel" vtec, it should be a smooth transition into the high lobe. at least that is what my car is like I have a stock jdm P30 and vtec engages anywhere from 5800 to 6500 depending on how hard I'm accelerating. the only thing I notice when vtec kicks in is a change in the sound of the engine as it starts to breath more

the stock ECU takes more factors into account than just rpm to determine when to switch to the high lobe on the cam, and unless you have tuned the vtec point on something other than a butt dyno you probably shouldn't mess with Honda's engineering

flame on

edit: it's very possible that installing new cams could change the vtec point because the ECU should be able to adapt to the new cams

 

[sohcslammer]

You are right in the fact that VTEC should be a smooth transition and not be "intense" but your X-over does NOT switch with throttle and cams. A ECU is programed to switch cam lobes at a pre-determened RPM. Always.

 

[omega11855]

n3g(negative) cams wont automatically change vtec point ecu cant adapt like that
but depending on load if ecu is still in closed loop vtec wont kick in neccisarily at a specified rpm for example i just drove to san fran and when i was coasting (dont ask but from la to san fran it was like 4.5hrs)(great time) at 5900 vtec didnt kick in it only kicked in if i got it to 6200 coasting ie not floored this is on a stock p73 ecu vtec point changes based on conditions but there are set parameters as i said regardless of how much throttle at 6200ish it changed over no mater what

 

[seanjuan]

this is what I found about vtec crossover

When to Switch Camshafts
The ECU is constantly comparing the torque curves of the low and high speed camshafts. It calculates the expected volumetric efficiency of the engine based on the current environmental conditions (air temperature and pressure) and the engine conditions (temperature, engine load, throttle position), and then derives the expected torque from the volumetric efficiency for each camshaft. Most of this has to be done anyhow in order to determine how much fuel to inject.

When conditions are right (the revs are over about 4500 rpm, the engine is warm, there is enough oil pressure to activate the pistons and the car is moving) the ECU will switch from the low to high speed camshaft when the expected torque of the low speed camshaft equals the torque of the high speed camshaft.

this is the page it came from


it seems to make sense to me

 

[sohcslammer]

Originally posted by omega11855@Aug 28 2003, 05:14 PM
n3g(negative) cams wont automatically change vtec point ecu cant adapt like that
but depending on load if ecu is still in closed loop vtec wont kick in neccisarily at a specified rpm for example i just drove to san fran and when i was coasting (dont ask but from la to san fran it was like 4.5hrs)(great time) at 5900 vtec didnt kick in it only kicked in if i got it to 6200 coasting ie not floored this is on a stock p73 ecu vtec point changes based on conditions but there are set parameters as i said regardless of how much throttle at 6200ish it changed over no mater what

Edit: OK, you're right.

And I made it from Lafayette to LA in 4 hours 10 minutes so (Yes, it's about 110-120 the whole way with 1 stop.)