VTEC Window (MAP vs RPM)
Joined: Aug 2016
Posts: 2,767
Likes: 234
From: In BOOST
Looks like nobody answered your actual question. It's an AND operation - so it must meet both conditions for it to kick in. The reason is because, without the pressure window, you could suddenly be entering VTEC while cruising on the highway at a low percentage of part throttle load. That's why there's a load threshold associated with VTEC (along with minimum coolant, minimum speed engagement, and disengage speed).
Here are some values you can use to start with and play around with if you have a test pipe. Note that I assume no responsibility if you mess things up. Also note that setting the Window Pressure RPM just slightly lower than the Lower point is also on purpose. I'll leave that as an exercise to the person learning how to tune why that's being done:
VTEC Window RPM Lower: 3600
VTEC Window RPM Higher: 5800
VTEC Window Pressure RPMs: 3400 4000 4500 6000 7200
VTEC Window Pressure MAP (bar): 0.940 0.920 0.800 0.500 0.300
Since you're reading the Hondata documentation, you should understand how to set your VTEC crossover at the optimal point. Hondata explains this very clearly in their documentation, so you'll obviously want to adjust this aforementioned data accordingly.
And having VTEC engage lower will not harm your motor so long as you aren't engaging it super low (around 2000 RPMs, for example). However, once you adjust your VTEC lower like this, you'll need to start tuning your fuel, timing, etc.
Here are some values you can use to start with and play around with if you have a test pipe. Note that I assume no responsibility if you mess things up. Also note that setting the Window Pressure RPM just slightly lower than the Lower point is also on purpose. I'll leave that as an exercise to the person learning how to tune why that's being done:
VTEC Window RPM Lower: 3600
VTEC Window RPM Higher: 5800
VTEC Window Pressure RPMs: 3400 4000 4500 6000 7200
VTEC Window Pressure MAP (bar): 0.940 0.920 0.800 0.500 0.300
Since you're reading the Hondata documentation, you should understand how to set your VTEC crossover at the optimal point. Hondata explains this very clearly in their documentation, so you'll obviously want to adjust this aforementioned data accordingly.
And having VTEC engage lower will not harm your motor so long as you aren't engaging it super low (around 2000 RPMs, for example). However, once you adjust your VTEC lower like this, you'll need to start tuning your fuel, timing, etc.
Setting the VTEC Window Pressure RPMs lower than where you want it is probably to make room for any delay in engagement by the ECU?
I'll be running a Hondata 4 bar MAP sensor, AEM wideband and AEM Series 2 ECU. Invidia 60mm TP, J's Racing FX70RS titanium single exit, stock airbox with an Apex'i dual funnel filter. Grams 1000cc injectors, AEM 340lph fuel pump. I live at altitude.
Joined: Jul 2014
Posts: 13,827
Likes: 1,549
From: Chesterfield VA
I'm running a 2006 DBW AP2 engine with just a K&N FIPK intake, Berk high flow cat, and Tanabe Medalion Touring exhaust none of which are documented to provide more than modest power gains. Road tuned Gernby Flash Pro tune with the result that VTEC will engage at 3600rpm -- at higher throttle openings. There is no VTEC Yo!, just a steady roll on of power and change of exhaust sound at that rpm. It's rpm AND throttle for sure as I can cruise at over 4000rpm in 6th gear on the low power cam and back roads at well above 4000rpm in 3d and 4th gears is the same. As I'm fond of writing "VTEC is just under my right foot."
Mid-range rpm is where we drive. I'd let your tuner determine what rpm VTEC is most effective. I didn't specify what rpm I wanted when the car was tuned and judging from Gernby's reputation I'm assuming this was optimal for my car.
-- Chuck
Mid-range rpm is where we drive. I'd let your tuner determine what rpm VTEC is most effective. I didn't specify what rpm I wanted when the car was tuned and judging from Gernby's reputation I'm assuming this was optimal for my car.
-- Chuck
Joined: Aug 2016
Posts: 2,767
Likes: 234
From: In BOOST
I'm running a 2006 DBW AP2 engine with just a K&N FIPK intake, Berk high flow cat, and Tanabe Medalion Touring exhaust none of which are documented to provide more than modest power gains. Road tuned Gernby Flash Pro tune with the result that VTEC will engage at 3600rpm -- at higher throttle openings. There is no VTEC Yo!, just a steady roll on of power and change of exhaust sound at that rpm. It's rpm AND throttle for sure as I can cruise at over 4000rpm in 6th gear on the low power cam and back roads at well above 4000rpm in 3d and 4th gears is the same. As I'm fond of writing "VTEC is just under my right foot."
Mid-range rpm is where we drive. I'd let your tuner determine what rpm VTEC is most effective. I didn't specify what rpm I wanted when the car was tuned and judging from Gernby's reputation I'm assuming this was optimal for my car.
-- Chuck
Mid-range rpm is where we drive. I'd let your tuner determine what rpm VTEC is most effective. I didn't specify what rpm I wanted when the car was tuned and judging from Gernby's reputation I'm assuming this was optimal for my car.
-- Chuck
Joined: Jul 2014
Posts: 13,827
Likes: 1,549
From: Chesterfield VA
@AP1Chief has a copy of my calibration (tune). I don't have the confidence to mess with tuning hence the Gernby road tune. I naively thought all I had to do was plug in FlashPro and type a few numbers in the boxes to get a lower VTEC, then I saw the fuel tables and other required changes and my eyes glassed over...
My VTEC engagement is more subtle than VTEC Yo! and I'm so used to it that it seems completely normal. Change in exhaust note is especially pleasing -- certainly sounds like more power. Swapped cars with a couple of guys and found it annoying to wait and wait and wait for VTEC engagement. The lower engagement is wonderful but no one will mistake it for supercharging.
As noted here and elsewhere there is no noticeable change in fuel use and reliability appears to be normal.
-- Chuck
My VTEC engagement is more subtle than VTEC Yo! and I'm so used to it that it seems completely normal. Change in exhaust note is especially pleasing -- certainly sounds like more power. Swapped cars with a couple of guys and found it annoying to wait and wait and wait for VTEC engagement. The lower engagement is wonderful but no one will mistake it for supercharging.
As noted here and elsewhere there is no noticeable change in fuel use and reliability appears to be normal.
-- Chuck
Joined: Aug 2016
Posts: 2,767
Likes: 234
From: In BOOST
@AP1Chief has a copy of my calibration (tune). I don't have the confidence to mess with tuning hence the Gernby road tune. I naively thought all I had to do was plug in FlashPro and type a few numbers in the boxes to get a lower VTEC, then I saw the fuel tables and other required changes and my eyes glassed over...
My VTEC engagement is more subtle than VTEC Yo! and I'm so used to it that it seems completely normal. Change in exhaust note is especially pleasing -- certainly sounds like more power. Swapped cars with a couple of guys and found it annoying to wait and wait and wait for VTEC engagement. The lower engagement is wonderful but no one will mistake it for supercharging.
As noted here and elsewhere there is no noticeable change in fuel use and reliability appears to be normal.
-- Chuck
My VTEC engagement is more subtle than VTEC Yo! and I'm so used to it that it seems completely normal. Change in exhaust note is especially pleasing -- certainly sounds like more power. Swapped cars with a couple of guys and found it annoying to wait and wait and wait for VTEC engagement. The lower engagement is wonderful but no one will mistake it for supercharging.
As noted here and elsewhere there is no noticeable change in fuel use and reliability appears to be normal.
-- Chuck
Your current tune sounds good. I also feel that the wait is a bit too long for VTEC engagement in a stock tune setting. At least a 1000 rpm lower engagement would have been nicer. I'll see once mine is tuned with lower engagement how it makes me feel. Can't wait.
Sure, I don't doubt reliability would be normal even with that really low engagement of yours
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Joined: Jul 2014
Posts: 13,827
Likes: 1,549
From: Chesterfield VA
Have you had personal experience with AP1 Chief tuning your car?
It's not just what rpm VTEC engages but what road speed. In 3d gear the tach and speedo match (pretty closely) so 3600rpm is 35mph and 5000rpm is 50mph. This means that at speeds of 35mph or higher I have instant VTEC available "under my right foot" in 3d gear or lower. Setting VTEC to 5000rpm means I'd need to be at 50mph in 3d or downshift to 2d to get the additional power. Running the back roads or city boulevards in 3d and 4th gears thru the curves and traffic with the engine running on the high power cam is fun.
Based on my experience (sample of 1) I don't see any benefit is easing into tuning by only dropping VTEC to 5000.
Don't forget you need a high flow cat to do this. Modified intake and exhaust may help (my car already had these) but don't seem to be necessary.
-- Chuck
Joined: Dec 2015
Posts: 812
Likes: 119
Lowering Vtec just helps with a smoother crossover, you don't want it too low, and loose velocity, you don't want it to high, and have 10-20hp/Tq Gains where vtec could be sooner. Your PEAK Hp/Tq wont change, but the power band will feel smoother, vs VTEECCC POWAA! and SNAP. lol
Joined: Aug 2016
Posts: 2,767
Likes: 234
From: In BOOST
Lowering Vtec just helps with a smoother crossover, you don't want it too low, and loose velocity, you don't want it to high, and have 10-20hp/Tq Gains where vtec could be sooner. Your PEAK Hp/Tq wont change, but the power band will feel smoother, vs VTEECCC POWAA! and SNAP. lol
Joined: Jul 2014
Posts: 13,827
Likes: 1,549
From: Chesterfield VA
Why wouldn't you want VTEC lower that 4500rpm? I consider it a waste of time and money to set VTEC at 4500. Gotta by the ECU or FlashPro and pay for a tune. My sample of one (1) indicates 3600 is wonderful and no negatives. Recall the VTEC setting is just one parameter. I'm never in VTEC cruising or when I don't want the extra power.
-- Chuck
-- Chuck