As my 4 cyl gets rolling from a stoplight, I notice a strong boost in perceived power around 30 mph, or so. I imagine that this has more to do with the car gaining inertia and overcoming it's weight "at rest," than it does with anything to do with the engine. Has anybody else noticed this? I almost feels like a turbo is kicking in and the car gets its real power.

Vtec Just KICKED IN YO! photos are about to storm your thread =)

My Accord is very old and does not have VTEC, but I do notice a surge of power if I hold a gear past 4000 RPM.

Now imagine what a V6 feels like. SUPER TWIN-TURBO INJECTION BOOST! WOOOSHHHHHHHH!

Sorry I just had to post this...haha :thmsup:

http://farm1.static.flickr.com/211/498395686_74bd9674db.jpg

Now imagine what a V6 feels like. SUPER TWIN-TURBO INJECTION BOOST! WOOOSHHHHHHHH!

Don't rub it in :(

Is is just you got into the power Band

V6 FTW

/rubbing it in.

V6 FTW

/rubbing it in.

Sorry, we only envy the 6-6 drivers.:lmao:

Damn. Hot rip. I'll crawl back to my corner now :sorry:


:thmsup:

Damn. Hot rip. I'll crawl back to my corner now :sorry:


:thmsup:
Ouch... you got burned.
Your post # is 666 :paranoid:

Ouch... you got burned.
Your post # is 666 :paranoid:

It's all about timing, timing is EVERYTHING! :D

Sorry, we only envy the 6-6 drivers.:lmao:

thats me :D

All these replies and not one answer thus far....

As my 4 cyl gets rolling from a stoplight, I notice a strong boost in perceived power around 30 mph, or so. I imagine that this has more to do with the car gaining inertia and overcoming it's weight "at rest," than it does with anything to do with the engine. Has anybody else noticed this? I almost feels like a turbo is kicking in and the car gets its real power.

ANSWER: Yes, it is easier to propel and object that is already in motion vs an object that is at rest. You notice something that I don't think is there. I'm not a physicist, but, I can tell you there is no additional boost or "Turbo". There's iVTEC in your car, but thats about it. What you feel is maybe the engagement of your exhaust valves. Prior to vtec engaging, your car runs on 12 valves, 2 intake and 1 exhaust valves per cylinder. After vtec engagement, its 2 in and 2 out per cylinder. That could be the difference. Also, in most cars, as the RPMs rise, there is more power produced, but i'm sure you are aware of that already. If you keep your engine speed between 3.5k and 6k rpm, you will always have power to perform almost any maneuver.

As far as numbers are concerned:
According to this: http://www.youtube.com/watch?v=Wvd37EDpAXM,
the 4cyl Accord coupe makes 125ft lbs to the wheel. No matter how you slice it, it doesn't have much go. In comparison, the V6 6MT has 200 ft lbs at 1900/2000 rpm and peaks out at around 225ft lbs. Weight difference between the 4cyl and the 6cyl is something like maybe 200lbs.

Lastly, don't get upset if people don't take your post seriously. It is difficult (imo) to take it seriously because you are talking about your perception of something that you think is there and I think that a large portion of people don't think the way you do in regards to this so called "turbo" boost sensation.

EDIT: I forgot to mention that your rate of acceleration probably peaks out at around 30, so maybe that has something to with it. By rate of acceleration I mean that from 0 to 10 MPH, it may take you 1.3 seconds to get there and from 10 to 20mph, 1.2 and from 20 to 30, 1.1 sec, 30 to 40, 1.2sec, 40 to 50mph, 1.5 sec and so on. I'll probably take you a good 10 seconds to get from 70 to 100mph.

Now imagine what a V6 feels like. SUPER TWIN-TURBO INJECTION BOOST! WOOOSHHHHHHHH!

not really..i test drove the v6 accord coupe at the honda dealer
honestly it doesnt feels like fast lol..

Auto v6 are dogs, with all that variable cylinder bullshit and other sensor nonsense its kind of pointless getting a v6. sure its faster than i4 but with the restrictions it has is it worth the money? a 6-6 on the other hand is a different animal, too bad I couldnt afford it the time i was buying my car

ANSWER: Yes, it is easier to propel and object that is already in motion vs an object that is at rest. You notice something that I don't think is there. I'm not a physicist, but, I can tell you there is no additional boost or "Turbo". There's iVTEC in your car, but thats about it. What you feel is maybe the engagement of your exhaust valves. Prior to vtec engaging, your car runs on 12 valves, 2 intake and 1 exhaust valves per cylinder. After vtec engagement, its 2 in and 2 out per cylinder. That could be the difference. Also, in most cars, as the RPMs rise, there is more power produced, but i'm sure you are aware of that already. If you keep your engine speed between 3.5k and 6k rpm, you will always have power to perform almost any maneuver.

As far as numbers are concerned:
According to this: http://www.youtube.com/watch?v=Wvd37EDpAXM,
the 4cyl Accord coupe makes 125ft lbs to the wheel. No matter how you slice it, it doesn't have much go. In comparison, the V6 6MT has 200 ft lbs at 1900/2000 rpm and peaks out at around 225ft lbs. Weight difference between the 4cyl and the 6cyl is something like maybe 200lbs.

Lastly, don't get upset if people don't take your post seriously. It is difficult (imo) to take it seriously because you are talking about your perception of something that you think is there and I think that a large portion of people don't think the way you do in regards to this so called "turbo" boost sensation.

EDIT: I forgot to mention that your rate of acceleration probably peaks out at around 30, so maybe that has something to with it. By rate of acceleration I mean that from 0 to 10 MPH, it may take you 1.3 seconds to get there and from 10 to 20mph, 1.2 and from 20 to 30, 1.1 sec, 30 to 40, 1.2sec, 40 to 50mph, 1.5 sec and so on. I'll probably take you a good 10 seconds to get from 70 to 100mph.

Thanks for some serious-minded discussion.

Of course I know there is no turbo there. There is a definite power surge circa 30 mph, though, so it might be the kick-in of the iVTEC that I am feeling. By the way, the 190 hp 4 cyl is plenty powerful for my needs and I have no dreams for the V6. Left behind two 6 cyl cars when I bought the Accord.

Thanks for some serious-minded discussion.

Of course I know there is no turbo there. There is a definite power surge circa 30 mph, though, so it might be the kick-in of the iVTEC that I am feeling. By the way, the 190 hp 4 cyl is plenty powerful for my needs and I have no dreams for the V6. Left behind two 6 cyl cars when I bought the Accord.

Well, with the 5 AT trans, i would guess that 30mph could happen in a couple of cases:

1. You are flooring it from rest, therefore you'll hit 30mph in 1st gear at a high point on the rpm gauge.

2. You are rolling along at some speed under 30mph and floor it, car switches gear to either 1st or 2nd (perhaps from 3rd or 4th gear during regular cruising) and you get this sensation.

_______________
To Its.BobO (however that is capitalized)

Don't compare the J35Z2 vs J35Z3. They feel absolutely different. Lets just say, that the Z3 is a champ and the Z2 is dud. The J35Z3 is probably one of the best, if not the best engine in terms of power delivery in its class. By class I mean a FWD coupe/sedan under 30k. And no, the 3.5SE Altima doesn't hold a candle to it. Well, maybe in some respects, but our engine is better. I could tell you why if you care to hear it.

Well, with the 5 AT trans, i would guess that 30mph could happen in a couple of cases:

1. You are flooring it from rest, therefore you'll hit 30mph in 1st gear at a high point on the rpm gauge.

2. You are rolling along at some speed under 30mph and floor it, car switches gear to either 1st or 2nd (perhaps from 3rd or 4th gear during regular cruising) and you get this sensation.

_______________
To Its.BobO (however that is capitalized)

Don't compare the J35Z2 vs J35Z3. They feel absolutely different. Lets just say, that the Z3 is a champ and the Z2 is dud. The J35Z3 is probably one of the best, if not the best engine in terms of power delivery in its class. By class I mean a FWD coupe/sedan under 30k. And no, the 3.5SE Altima doesn't hold a candle to it. Well, maybe in some respects, but our engine is better. I could tell you why if you care to hear it.

No, it's not a transmission kick-down effect. I'm letting the car upshift naturally through the gears without pushing it hard.

i think i actually get what he's saying...when im slowly pushing the gas and wait till like 3,500 rpm or 20mph, if i push the gas a little more(not flooring it) it feels lik a little boost b4 it goes into 2nd....

I doubt your feeling Vtec as in high cam lobe kick it as thats only up ay around 5k it happens. the VTC on the other hand is pretty dynamic through out rpm range, starts much lower to alter cam timing.

I think most just feel that its tuned for good midrange torque, which starts around 3500 and maxes at 4500 or so, (the K24Zx does seem to have nice flat powerband once you get up there (3500-4000rpm an up)

Auto v6 are dogs, with all that variable cylinder bullshit and other sensor nonsense its kind of pointless getting a v6. sure its faster than i4 but with the restrictions it has is it worth the money? a 6-6 on the other hand is a different animal, too bad I couldnt afford it the time i was buying my car

what are the other sensor nonsense and what are the restrictions please?

Well, with the 5 AT trans, i would guess that 30mph could happen in a couple of cases:

1. You are flooring it from rest, therefore you'll hit 30mph in 1st gear at a high point on the rpm gauge.

2. You are rolling along at some speed under 30mph and floor it, car switches gear to either 1st or 2nd (perhaps from 3rd or 4th gear during regular cruising) and you get this sensation.

_______________
To Its.BobO (however that is capitalized)

Don't compare the J35Z2 vs J35Z3. They feel absolutely different. Lets just say, that the Z3 is a champ and the Z2 is dud. The J35Z3 is probably one of the best, if not the best engine in terms of power delivery in its class. By class I mean a FWD coupe/sedan under 30k. And no, the 3.5SE Altima doesn't hold a candle to it. Well, maybe in some respects, but our engine is better. I could tell you why if you care to hear it.

- what is the difference between Z2 and Z3?

- Please tell us why our engines are better than the Altima's V6.

- what is the difference between Z2 and Z3?

- Please tell us why our engines are better than the Altima's V6.


1. Z2 version is VCM. Z3 version is w/o VCM. The Z3 is a more powerful motor. For further investigation, you should research Dyno test graphs. The Z3 engine produces approx. 240HP and approx 220 to 225 lbs. ft. of torque to the wheels. The Z2 produces approximately 30hp and 30 lbs. ft. torque less to the wheel.

2a. One thing that makes our engine better in my opinion is that we have less moving parts. The Altima has a DOHC V6, while we have a SOHC V6 and yet, our engines ( the Z3 variant) perform marginally better on the street.

2b. From what I've heard/read, the Nissan V6 requires premium gasoline to produce its 270hp. Our engines (Z2/Z3) require only regular grade gas to produce 271hp. Although the VQ engine line from Nissan has been very successful, I would always pick a Honda motor over a Nissan motor, but this is strictly my opinion only.

From Consumerguide.com :
In Consumer Guide testing, a 3.5 SE sedan with CVT averaged 23.8 mpg in mostly highway driving, 19.1 with more city work, including gas-eating performance runs. Also in mostly highway driving, manual-transmission 3.5 SE models averaged 22.8-24.8 mpg. A Hybrid averaged 29.2 mpg in mostly city driving. No opportunity to measure with a conventional 4-cylinder model. Altima 2.5s use regular-grade gas. Nissan recommends premium for 3.5s. Note that Altima has a 20-gallon fuel tank, among the largest in the midsize-car class.

1. Z2 version is VCM. Z3 version is w/o VCM. The Z3 is a more powerful motor. For further investigation, you should research Dyno test graphs. The Z3 engine produces approx. 240HP and approx 220 to 225 lbs. ft. of torque to the wheels. The Z2 produces approximately 30hp and 30 lbs. ft. torque less to the wheel.

2a. One thing that makes our engine better in my opinion is that we have less moving parts. The Altima has a DOHC V6, while we have a SOHC V6 and yet, our engines ( the Z3 variant) perform marginally better on the street.

2b. From what I've heard/read, the Nissan V6 requires premium gasoline to produce its 270hp. Our engines (Z2/Z3) require only regular grade gas to produce 271hp. Although the VQ engine line from Nissan has been very successful, I would always pick a Honda motor over a Nissan motor, but this is strictly my opinion only.

From Consumerguide.com :
In Consumer Guide testing, a 3.5 SE sedan with CVT averaged 23.8 mpg in mostly highway driving, 19.1 with more city work, including gas-eating performance runs. Also in mostly highway driving, manual-transmission 3.5 SE models averaged 22.8-24.8 mpg. A Hybrid averaged 29.2 mpg in mostly city driving. No opportunity to measure with a conventional 4-cylinder model. Altima 2.5s use regular-grade gas. Nissan recommends premium for 3.5s. Note that Altima has a 20-gallon fuel tank, among the largest in the midsize-car class.

Thanks for the info. But isn't the difference in WHP and WTQ between what the Z2 and Z3 produce a factor of transmission?

Thanks for the info. But isn't the difference in WHP and WTQ between what the Z2 and Z3 produce a factor of transmission?

Not entirely. If the HP rating at the crank is 271 and Hp rating at the wheels is 210hp. That is a 22.5% loss. I think that attributing between 1/5th to 1/4th loss in hp to just the automatic transmission wouldn't be a good idea. There are other factors at play as well. The Z3 has a "high performance" intake manifold. I do not know all of the specifics, but i am positive that it plays a part. As well as exhaust flow, as the Z3 engine has a higher exhaust flow by a small margin.

Not entirely. If the HP rating at the crank is 271 and Hp rating at the wheels is 210hp. That is a 22.5% loss. I think that attributing between 1/5th to 1/4th loss in hp to just the automatic transmission wouldn't be a good idea. There are other factors at play as well. The Z3 has a "high performance" intake manifold. I do not know all of the specifics, but i am positive that it plays a part. As well as exhaust flow, as the Z3 engine has a higher exhaust flow by a small margin.

I attribute the loss in hp to just the transmission becuase both engines produce almost the same bhp and tq at the crank. the Z2 even produces more tq at the crank than the Z3 does, 254 vs 251 lb-ft both @ 5000 rpm!

I attribute the loss in hp to just the transmission becuase both engines produce almost the same bhp and tq at the crank. the Z2 even produces more tq at the crank than the Z3 does, 254 vs 251 lb-ft both @ 5000 rpm!

To each their own.

1. Z2 version is VCM. Z3 version is w/o VCM. The Z3 is a more powerful motor. For further investigation, you should research Dyno test graphs. The Z3 engine produces approx. 240HP and approx 220 to 225 lbs. ft. of torque to the wheels. The Z2 produces approximately 30hp and 30 lbs. ft. torque less to the wheel.

2a. One thing that makes our engine better in my opinion is that we have less moving parts. The Altima has a DOHC V6, while we have a SOHC V6 and yet, our engines ( the Z3 variant) perform marginally better on the street.

2b. From what I've heard/read, the Nissan V6 requires premium gasoline to produce its 270hp. Our engines (Z2/Z3) require only regular grade gas to produce 271hp. Although the VQ engine line from Nissan has been very successful, I would always pick a Honda motor over a Nissan motor, but this is strictly my opinion only.

From Consumerguide.com :
In Consumer Guide testing, a 3.5 SE sedan with CVT averaged 23.8 mpg in mostly highway driving, 19.1 with more city work, including gas-eating performance runs. Also in mostly highway driving, manual-transmission 3.5 SE models averaged 22.8-24.8 mpg. A Hybrid averaged 29.2 mpg in mostly city driving. No opportunity to measure with a conventional 4-cylinder model. Altima 2.5s use regular-grade gas. Nissan recommends premium for 3.5s. Note that Altima has a 20-gallon fuel tank, among the largest in the midsize-car class.

I won't even go into a 3.5 Nissan vs Accord 3.5, way to many varibles but your #2 comment SOHC better than DOHC I disagree totally.

If the 3.5 had DOHC + VTC it would really perform as you now have full control over intake overlap timing, High/low cam profiles on both cam's if needed. I would bet 310-320HP would be not hard at all.
Also with VTC you don't need the EGR value which sends exhaust gases into intake (and is a maintenance issue) to dilute the charge.
Acura has enabled Vtec on both intake and exhaust values to produce 305 Hp by a redesign of valvetrain.
My guess if they did true DOHC with all features (Vtec+VTC) the head width would be more than they like.

DOCH is typically better than SOHC

I didn't comment on DOHC vs SOHC being better. I said that less moving parts is better.

I am surprised no one has mentioned the drive by wire throttle. Besides the i-vtec engaging, that is also a likely culprit to what your feeling. IMO, SOHC vs DOHC is a not a worthwhile debate. DOHC is the obvious winner simply by design. 4 smaller valves are better than 2 big ones for flow, look at the older 4.6 mustang cobras as a good example. It is much easier to do this with a DOHC motor than a SOHC, In most cases you can also turn more RPM because you don't need to use large/long rocker arms to get to the valves as you do with a SOHC head. You can also have full timing control through cam phasing, Jaguar uses it on their v8 DOHC motors

I didn't comment on DOHC vs SOHC being better. I said that less moving parts is better.

:thumbsup: This is the main reason rotaries own piston engines. For power to weight, and power per liter they cannot be beat. Too bad they run so dirty:naughty:

All these replies and not one answer thus far....

thats because this is the most rediculous post of rediculous posts.

I am surprised no one has mentioned the drive by wire throttle. Besides the i-vtec engaging, that is also a likely culprit to what your feeling. IMO, SOHC vs DOHC is a not a worthwhile debate. DOHC is the obvious winner simply by design. 4 smaller valves are better than 2 big ones for flow, look at the older 4.6 mustang cobras as a good example. It is much easier to do this with a DOHC motor than a SOHC, In most cases you can also turn more RPM because you don't need to use large/long rocker arms to get to the valves as you do with a SOHC head. You can also have full timing control through cam phasing, Jaguar uses it on their v8 DOHC motors

Thats all true, DOHC would allow simpler design as the rockers and cam lobes could be spread out over each cam better. It also allows spark plug positioning at upper center position in head, something the SOHC needs slight angled to clear cam.

But the 3.5 is a 4 valve setup, just done with rocker arms.

:thumbsup: This is the main reason rotaries own piston engines. For power to weight, and power per liter they cannot be beat. Too bad they run so dirty:naughty:
Thats because the 12-13b combustion volume is so large in RX7+ which hursts emission and mpg.

They do perform great, the 1992 Rx7 sequential turbo was real performer

But the 3.5 is a 4 valve setup, just done with rocker arms.

Hence the 6800 chip. My bet is the bottom end is capable of higher RPM's but the valve train is not up to it.:dunno:

Thats because the 12A-13b combustion volume is so large in RX7+ which hursts emission and mpg.

They do perform great, the 1993 Rx7 sequential turbo was real performer *fixed*
93-2002 RX-7, aka FD ....IMO one of the most beautiful sports cars(and fastest off the showroom floor in 1993) designed to this day. The c5 vet body is a direct rip, just done 4 years later.
It not that the volume is so large, it is that there is so much overlap in the combustion stroke. To make more power(porting the rotor housings), you increase the overlap making it even dirtier...ugh.
I have had 5 rx-7's so far in life, I know all about rotary power, problem is the Smog nazis here in CA.

*fixed*
93-2002 RX-7, aka FD ....IMO one of the most beautiful sports cars(and fastest off the showroom floor in 1993) designed to this day. The c5 vet body is a direct rip, just done 4 years later.
It not that the volume is so large, it is that there is so much overlap in the combustion stroke. To make more power(porting the rotor housings), you increase the overlap making it even dirtier...ugh.
I have had 5 rx-7's so far in life, I know all about rotary power, problem is the Smog nazis here in CA.

I am pretty sure 1992 started the twin turbo RX7 (new body style).

The overlap is done in the side housings, there is also 6 port 13b but there NA builds only with secondary ports.
I used to work for Prototype motorcars which focused on Rx7, all performance items on them, including internal engine work.

Anyway real fun car to drive. Sorry for getting off topic.

I am pretty sure 1992 started the twin turbo RX7 (new body style).

The overlap is done in the side housings, there is also 6 port 13b but there NA builds only with secondary ports.
I used to work for Prototype motorcars which focused on Rx7, all performance items on them, including internal engine work.

Anyway real fun car to drive. Sorry for getting off topic.

Series 6 was made in late 92 but sold in USA and CA as 93 my. N.A. was a bit behind the rest of the world for the series 6, they were still selling series 5's as 92 my at a lot of dealers in north america, so mazda delayed it a year.

The intake ports are in the side housings (except the rx8 motor) exhaust ports are in the rotor housings:thmsup:.

You see, if Honda made their V6s DOHC VTEC....it would just be too powerful. :D

Like this one:

http://www.nsxprime.com/photopost/data/668/11482engine1.jpg

The SOHC 4 valve RL v6 isn't too shabby! Vtec on all 4 valves!

Engine type
Aluminum alloy V-6 engine
Valvetrain
Variable valve Timing and lift Electronic Control (VTEC™) for intake and exhaust valves, 4 valves per cylinder, with a belt-driven single overhead camshaft
Displacement (liters)
3.7
Compression ratio
11.2:1
Horsepower @ rpm (SAE net)
300 @ 6300
Torque lbs-ft @ rpm
271 @ 5000
Redline
6800 rpm

Not at all, even though I ended up with a 2.4 I test drove several V6s. IMO the Honda/Acura's were in a class of their own. Might be b/c the Altima coupe was a rubberband tranny but I didn't care for it at all.

I think I just like the high-revver feel more of the S2000 and the Mazda rx-8, those were my two top choices but I had to stay on the side of practicality :)

*disclaimer, do not bring rotary engines/ rx-7/8's into your thread or I will jack it*

If you know how to drive, BOTH of those cars are a blast to wind up to the moon on a nice empty canyon. Too bad the 2000 is done after this year.

I still want to get an S2000 in a couple years once my car is paid off. I just decided I didn't want one as an everyday car, not to mention the ridiculous insurance. I'd rather have a car like that to keep around for only nice days.

And well the RX8 was just ridiculous on insurance, granted my Accord ended up being high too so I gave Allstate the finger and went to the gecko...I can't believe someone with no tickets/wrecks and Allstate wanted ~$200/month for a 4cyl Accord, age 24 or not, that's pathetic. My 1991 Accord's insurance was only $58/month.

You see, if Honda made their V6s DOHC VTEC....it would just be too powerful. :D

Like this one:

http://www.nsxprime.com/photopost/data/668/11482engine1.jpg

LOL NSX
I want engine swap. LMAO

Oh no that's not an NSX that's the engine in my Civic dawg, I can outrun a Veyron now and my coffee can exhaust sounds like a F1 car :lmao:

thats because this is the most rediculous post of rediculous posts.

5 whole posts here and you are an expert? :notworthy

BTW, "ridiculous" is spelled this way.

5 whole posts here and you are an expert? :notworthy

BTW, ridiculous is spelled this way.

You forgot to mention, its SKILLS, not SKILLZ.

You forgot to mention, its SKILLS, not SKILLZ.

Well, as you say, ignorance is bliss. :)

What you feel is maybe the engagement of your exhaust valves. Prior to vtec engaging, your car runs on 12 valves, 2 intake and 1 exhaust valves per cylinder. After vtec engagement, its 2 in and 2 out per cylinder.
That is wrong buddy; VTEC engines run in 4 valves all the time. VTEC engages on the INTAKE valves at a predetermined rpm (around 5K), and it's simply a more aggressive cam-lobe profile.

And our SOHC has MORE moving parts than a DOHC due to the rocker arms. And if you add VTEC, that's even more; I prefer a DOHC without VTEC over our SOHC VTEC all day long, but most have cam phasing now (which is MUCH more effective), and many on BOTH intake and exhaust.

And don't get me started with the stupid belts, rather than cam chains. VTEC was all the rage 2 decades ago. Our V6 without DOHC, hydraulic valve lash adjustment, and cam chains is just unacceptable; yeah, it's a good engine, but Honda seems to just be resting ln its laurels lately. Our engine is basically the same darn thing that debuted on the first V6 Acura 23 years ago; it's time for something better. I'd be okay with at least chains; the valves are relatively easy to adjust, but changing the belts is a major PITA. Enough for today :D. Take care man.

ELP, you are about the only person who I won't argue because you most likely know better. Thanks for the info.

Elp_JC is correct.