VTEC questions

paxmanhorn · 08-30-2005, 12:59 AM

Ok, here's the situation. (My parents went away on a weeks vacation...) I am currently driving a 93 Del Sol Si, which has the sneaky VTEC engine without being properly labelled on the valve cover. (That really hurts my feelings, by the way) It was my wife's car since '95, but now that we have kids it has become my daily driver. I have been very gentle with it because it has 127,000 miles on it and I wasn't sure when (if ever) the timing belt had been changed. I recently changed the belt and now have more confidence with being a bit heavier on the gas pedal. My question is this: How can you really 'tell' that VTEC is kicking in, and when does it kick in? Is it a variable thing depending on the load on the engine at any given moment, or does it kick in at a certain RPM? I know the ECU is in charge of that, but when is it supposed to happen? The reason I ask is because I have been getting it up to 6,000 - 6,500 rpm (It's an automatic, by the way) in 2nd and 3rd gear, but haven't noticed any significant change in the power at any given RPM level. I'm just trying to determine whether my VTEC is actually working, or am I just not very perceptive? Thanks in advance for any info you can provide, and I look forward to being flamed by the gearheads for not knowing my own car better.

Love and kisses,

Carl in TX

t_fuNk · 08-30-2005, 05:35 PM

Well Carl, I just got a lot of people attempting to explain to me what VTEC is, so hopefully I can explain it clearly. VTEC is, as you know, variable timing. It kicks in based on speed and RPM's. It was made as to shift smoothly, this may be why you aren't feeling it. It is also possible that, for various reasons, the VTEC solenoid is not functioning in which case it is just a normal engine. At 6500 RPM, VTEC should definetly engage. I beleive it engages between 4000 and 6500 RPM's. It is different on the various models and engines. I hope this answers your question.

iVteC_PoWeR · 08-30-2005, 07:52 PM

VTEC stands for (V)ariable Valve (T)iming and (E)lectronic Lift (C)ontrol. I'm not sure at what exact rpm vtec engages on a del sol vtec but it should DEFINITELY be in by 6500rpm. Is there a change in sound when you rev higher besides the high pitch scream of the motor? In a B16 you should definitely feel vtec kick in.

flameboy79 · 08-31-2005, 10:22 AM

VTEC should engage around 5,400 RPM for an auto as far as I know but on the model you have it will not be that noticeable. Less noticeable on the SOHC models plus less noticeable on an automatic. You should feel a little more pull from the car. On the DOHC VTEC there is no missing it

Like said, if you are convinced there is no change perhaps your VTEC is not engaging. This could be solenoid, oil pressure etc. Best thing to do is to bridge the servicew connector on your ECU and that way any fault codes can be flashed to the dash which may indicate why its not working.

Let me know if you would like some further info.

iVteC_PoWeR · 09-03-2005, 04:56 PM

a Del Sol vtec has a B16a1 i believe so it is a dohc vtec and you should definitely feel vtec engage.

paxmanhorn · 09-04-2005, 02:44 PM

I appreciate that, but my car (as is stated in the original post) is an Si, not a VTEC. The VTEC model wasn't available in 93, and so the stock engine is a D16Z6.

Raziel · 09-04-2005, 10:06 PM

You have VTEC its a little less notice able with the SOHC like in our SIs but in seconds gear, because u have to be going faster then 25-30 for it to kick in, hit 5.5k rmps. and listen to your enigne, it will drasticly increase in loudness, especaily if u have intake and / or exaust. around 6.5-7 grand is when it fully engages. Just go out on a road thats not to busy and slam ur gas and take off... second gear and higher look at ur rpms and listen to ur engine u will start to hear it cry but as soon as u hit 5.5 the sound becomes so much louder due to the extra exaust valves opening... let her wind up to like 6.5 and dump the clutch shift and do it again. Oh yea btw I have 96 so my red line doesnt start til 7 and urs starts at 6.5 so i wouldnt really advice going that high. just hit 5.5 and go to 6.2 and shift. ull still hear it.

paxmanhorn · 09-05-2005, 01:01 AM

again, thanks for the info, but my car (as stated in the original post) is an automatic. So I can't decide at what RPM the gears will change, unless I use the 1,2, and D3 shifter locations. Also, there aren't any extra exhaust valves that open when VTEC engages, it's the lift of the valves that changes, not the number of valves used. And one other thing, the redline on my car is 7,200 rpm, not 6,500. But thank you for trying to answer my question. Thanks to all who tried to help me out.

Plastic_Fork · 09-05-2005, 07:11 PM

On a SOHC D16Z6 engine you have VTEC lobes on the intake only. No VTEC on the exhaust lobes. I'm not sure exactly what rpm VTEC engages on an automatic Si, but for the B16A equipped Del Sol the VTEC engagement point is 5400 rpm's. It's not a drastic increase in noise unless you have an aftermarket intake or remove the OEM resonator. Before I did both, I could barely hear the change in pitch the motor made. And the pull isn't that much a kick in the pants as people think. The changeover on a stock Del Sol is rather smooth so really the only thing I notice is noise level and acceleration.

If you want to be sure, as suggested go on an open road or the interstate and mash on the pedal so you're at wide open throttle. When VTEC engages, you should hear an audible change in sound pitch the motor makes and you might perhaps feel better pull and torque. I think the VTEC engagement on an auto Si is somewhere around 6,000 rpm's but I could be wrong.

Raziel · 09-05-2005, 11:05 PM

Well yeah, it doesnt open extra valves it chagnes the way the cam lobs work.But as far as controling how high ur rpms go, if u mash the gas and dont let off the rmps should tach high enough before it shifts, just dont let of the gas as soon as u do that it will shift but if u stay on it it wont shit til near red line.

94SolGrl · 09-07-2005, 12:34 PM

you can hear it. One of my sols is an auto 93 Si, and the tone of the engine changes. When it drops a gear (like climbing hills), is where you usually hear it. But with a stock motor setup, it is extremely muffled. I didn't really hear it on my other sol, which until recently was a manual tranny D16, until I did the intake and exhaust. You don't really feel it too much on the D, except that it seems like the motor has a much easier time accelerating. On the b series, however, with enough work, you do actually feel the extra pull when it engages. Remove the resonator box if you wanna hear it. But my auto Si is my daily driver... it's what I drive when the other one (which is now a b18c1 hybrid) gives me a headache.

Plastic_Fork · 09-08-2005, 03:18 PM

Quote:

Originally Posted by 94SolGrl

it's what I drive when the other one (which is now a b18c1 hybrid) gives me a headache.

Still have a dual exhaust setup, Emily? I hope to find the RS*R ExMag when the time comes (especially now that it's been discontinued...

). Nice n' quiet.

94SolGrl · 09-08-2005, 05:01 PM

Eventually I'll be going back to the duals. I thought about just doing one, but I like the duals too damn much.

And especially running boost... less backpressure ;-)

Plastic_Fork · 09-08-2005, 06:36 PM

lol Yeah, I figured you'd keep the duals. What pipe diameter do you have? 3" exhaust?

94SolGrl · 09-09-2005, 10:15 AM

2.5" from the cat to the split for the pipes, then 2.25" running around the gas tank, finished off with polished 3" tips.

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