Go Back   Team-BHP > Under the Hood > Technical Stuff


Reply
 
Thread Tools Search this Thread
Old 12th January 2009, 11:30   #1
BHPian
 
hrishig's Avatar
 
Join Date: Apr 2007
Location: Pune
Posts: 372
Thanked: 12 Times
Default Honda i-dsi, vtec , ivtec comparision

( Mods pl merge / move the thread if needed )

Here is the graph that I found while surfing







Does this mean that

1) All 3 engines should perform similar below 3000 - 3500 rpm?

2) The advantage of i-vtec over vtec can be seen only after 5000 rpm?
hrishig is offline   Reply With Quote
Old 12th January 2009, 11:38   #2
Senior - BHPian
 
ashthedivx's Avatar
 
Join Date: Feb 2007
Location: Delhi
Posts: 1,351
Thanked: 22 Times
Default

Is the said difference is on paper only or the New Honda City loaded with i-vtec is literally so much lethal ??
ashthedivx is offline   Reply With Quote
Old 12th January 2009, 12:23   #3
Senior - BHPian
 
Join Date: Nov 2007
Location: Bangalore
Posts: 2,376
Thanked: 528 Times
Default

Doesnt look very accurate. i-Dsi is supposed to have better torque at low RPMs then VTechs.
Guna is offline   Reply With Quote
Old 12th January 2009, 12:34   #4
Senior - BHPian
 
alpha1's Avatar
 
Join Date: Apr 2007
Location: P00NA
Posts: 1,626
Thanked: 967 Times
Default

^ You might be comparing two different engines in that case.

The only difference between a vtec and non-vtec engine is experience above ~4500 RPMs. So all the torque/power curves below should be same.
alpha1 is offline   Reply With Quote
Old 12th January 2009, 13:36   #5
BHPian
 
hrishig's Avatar
 
Join Date: Apr 2007
Location: Pune
Posts: 372
Thanked: 12 Times
Default

Quote:
Originally Posted by Guna View Post
Doesnt look very accurate. i-Dsi is supposed to have better torque at low RPMs then VTechs.

??
Is this true? Is there any source / link which can confirm this?
hrishig is offline   Reply With Quote
Old 12th January 2009, 13:48   #6
Senior - BHPian
 
Join Date: Nov 2007
Location: Bangalore
Posts: 2,376
Thanked: 528 Times
Default

Quote:
Originally Posted by hrishig View Post
??
Is this true? Is there any source / link which can confirm this?
I remember having read about this, probably in Autocar, but can't seem to get the same source.
Here is another article I found which says "Compared to the 88ps I-DSI engine, the VTEC engine delivers in the upper mid to high rpms. Indeed, at rpms below 3,000, the VTEC actually delivers less torque (i.e. less power) than the I-DSI, consistently 0.2kgm across the relevant rpm range."

Source: Honda City | Automobile and Car Review India
Guna is offline   Reply With Quote
Old 12th January 2009, 17:54   #7
Senior - BHPian
 
ImmortalZ's Avatar
 
Join Date: Jan 2008
Location: Trivandrum
Posts: 2,133
Thanked: 139 Times
Default

Guys, discussing the differences between VTEC, i-VTEC and i-DSI is opening a big can of worms.

Honda has used the VTEC nomenclature for large number of different technologies for their heads dealing with creative valve timing.

Get a big cuppa coffee and settle down for a read of the wikipedia page or if you really want a technical discourse, the Temple of VTEC Asia articles.

It is all very confusing, but very revealing.
ImmortalZ is offline   Reply With Quote
Old 13th January 2009, 09:36   #8
BHPian
 
Join Date: Apr 2006
Location: North America
Posts: 960
Thanked: 3 Times
Default

Well Honda actually cheat a bit on their VTEC/i-VTEC valvetrains.

They only have that system on the intake valves, not on both intake and exhaust, like what Mitsubishi or Toyota or a ton of other companies have.
But there's nothing wrong with it, as long as it works.

But what it basically is that they have two different camshaft profiles on the camshaft, so depending on your "requirement", it is chosen by the ECU.

The two different profiles mostly affect the valve lift (only the intake in a VTEC). So if you gun it, it switches to the more aggressive profile and the valve opens more and for a longer time and hence more fuel+air is injected in the cylinder.

Whereas in economy mode, the opposite happens.

I'd guess that the i-DSI works in a similar way, but I could be wrong.

Most of the different manufacturers have their own version of VTEC, where they vary the different aspects of the intake and exhaust stroke to achieve different characteristics (like valve overlap, ignition delay etc.)

Last edited by sujaylahiri : 13th January 2009 at 09:40.
sujaylahiri is offline   Reply With Quote
Old 13th January 2009, 10:46   #9
Senior - BHPian
 
Join Date: Nov 2007
Location: Bangalore
Posts: 2,376
Thanked: 528 Times
Default

Quote:
Originally Posted by sujaylahiri View Post
I'd guess that the i-DSI works in a similar way, but I could be wrong.
One thing about i-DSI is, it has dual spark plugs which ignite with a fractional delay, supposedly resulting in better combustion.

Whatever the curves show, I have felt the new i v-tech to be more lively and responsive in the low end also, compared to i-DSI
Guna is offline   Reply With Quote
Old 13th January 2009, 12:19   #10
BANNED
 
hellspawn's Avatar
 
Join Date: Jul 2005
Location: noida
Posts: 1,686
Thanked: 6 Times
Infractions: 0/1 (10)
Default

Well if you observe the i-dsi has an almost flat torque curve between 2000-4000rpm.This is why its easier to drive in the city.
hellspawn is offline   Reply With Quote
Old 13th January 2009, 13:26   #11
Senior - BHPian
 
Shan2nu's Avatar
 
Join Date: Feb 2004
Location: Hubli - Karnata
Posts: 5,525
Thanked: 87 Times
Default

Quote:
Well Honda actually cheat a bit on their VTEC/i-VTEC valvetrains.

They only have that system on the intake valves, not on both intake and exhaust, like what Mitsubishi or Toyota or a ton of other companies have.

The two different profiles mostly affect the valve lift (only the intake in a VTEC). So if you gun it, it switches to the more aggressive profile and the valve opens more and for a longer time and hence more fuel+air is injected in the cylinder.
Firstly, VTEC doesn't only vary the lift but also the duration of the valves.

2ndly, Honda does have engines that use VTEC on the intake as well as the exhaust valves (mostly DOHCs). Even the B16s had this.

U can read more about the different types of VTEC engines here - VTEC

Shan2nu
Shan2nu is offline   Reply With Quote
Old 13th January 2009, 18:41   #12
BHPian
 
Join Date: Apr 2006
Location: North America
Posts: 960
Thanked: 3 Times
Default

Quote:
Originally Posted by Shan2nu View Post
Firstly, VTEC doesn't only vary the lift but also the duration of the valves.

Shan2nu
If you read my post again carefully, you'll see that I've talked about it as well.

"valve opens more and for a longer time and hence more fuel+air is injected in the cylinder"


I didn't know exactly what engines have VTEC on both intake and exhaust, but some of the more popular ones these days don't.
sujaylahiri is offline   Reply With Quote
Old 13th January 2009, 22:28   #13
Senior - BHPian
 
ImmortalZ's Avatar
 
Join Date: Jan 2008
Location: Trivandrum
Posts: 2,133
Thanked: 139 Times
Default

K20A - Civic Type-R, Integra Type-R, Accord Euro-R (225BHP)
K20A2 - RXS - S (200BHP)

The K20A2 I believe is one of the most sought after swaps for Honda cars in the world. People swap it into anything from a 88 to 2009 Civic, Prelude, Del Sol and even Fits. Some bolt the head to a K24A8 Accord engine to get a frankenstein torque monster.

Nice info here.

Last edited by ImmortalZ : 13th January 2009 at 22:32.
ImmortalZ is offline   Reply With Quote
Old 14th January 2009, 12:35   #14
BHPian
 
hrishig's Avatar
 
Join Date: Apr 2007
Location: Pune
Posts: 372
Thanked: 12 Times
Default

After reading various article on net regarding the idsi and vtech comparision it is for sure that the idsi max torque is near 2800rpm and for vtech it is somewhere near 4500 rpm. The bad thing is both these cars have same rpm meter which is perfect for vtech but not so perfect for idsi.

Means for idsi , most of the buys will not cross 4500 mark as car starts screeming , yet the max rpm value is around 7-8k So for i-dsi the additional values are useless.
hrishig is offline   (1) Thanks Reply With Quote
Reply


Thread Tools Search this Thread
Search this Thread:

Advanced Search


Similar Threads
Thread Thread Starter Forum Replies Last Post
Nintendo DS Lite / Nintendo DSi rkavthekar Gadgets, Computers & Software 13 28th July 2011 19:32
Honda CR-V 2.4 iVTEC driven Revvmaster Test-Drives & Initial Ownership Reports 9 22nd May 2006 00:10


All times are GMT +5.5. The time now is 02:11.

Copyright 2000 - 2017, Team-BHP.com
Proudly powered by E2E Networks