i-DSI v VTEC?

[guest1060]

What is the difference between the i-DSI 1.4 engine in the pre-2008 model and the VTEC engine in the 2008 - model?  Does this mean Honda have abandoned the i-DSI engine possibly as horribly complicated and gone back to the established VTEC technology?

I have just bought a one year old 1.4 i-DSI and am now worrying about servicing costs!

[culzean]

Take a look at the link below for full description of both I-DSi and VTEC engines in the Jazz.

The I-DSi is not 'horribly compicated' but is actually simpler than the V-TEC and is quite a feat of engineering in itself - being able to run an engine with a 10.8:1 compression ratio on regular 95RON unleaded fuel.

I have driven V-TEC engined Honda cars before and loved the 'dual personality' of the V-TEC, but as a relaxed everyday commuter vehicle the I-DSi Jazz takes a lot of beating.

http://asia.vtec.net/Series/FitJazz/lseries/

[culzean]

If you are worried about the dreaded £350 charge for 'checking valve clearances' forget it - we have two older Jazzes than you have just purchased and both have done over 60K without having the valves checked without a single problem with emissions etc. and the later ones (after 2006 I think, were 60K checks anyway).

Servicing only consists of oil and filter changes every 12K and sparkplugs about every 24K - which means if you get the dealer to do it you will be paying about £120 for a cup of coffee in the dealers waiting area.  Do it yourself and use decent oil (and Honda filters) and you will save a lot of money and as a bonus also learn a lot about your Jazz .

[RichardA]

I heard rumors that i-DSi was dropped to 'knocking', but I've never been able to verify that claim even on the internet.

[culzean]

Maybe some 'supermarket' fuels may cause knocking, but I don't use them and have never had a problem. My wife used to put supermarket fuel in her Jazz and I heard it knocking a few times when I drove it. I filled it up with 'normal' petrol a few times and when she felt how much better it ran she stopped using supermarket fuel. 

I do tend to use 'V-Power' or 'Ultimate' every so often and normally get an extra 4 to 5 mpg from it - and the car does feel smoother and livelier so the extra mpg cancels out the extra I pay for better fuel.

[E27006]

The 8 valve Dsi engine is very alive and kicking,  the new Insight has it.

They call it e-Vtec instead of Dsi because they have a mechanism to hold the valves open during fuel-cut coasting, with the valves held open reduces engine braking and pumping losses,  the car rolls further and mpg improves.

I have driven both a 1.2Se Jazz Vtec  GE model and 1.4 Dsi GD in a back to back road test,  Ge gave better mpg over Dsi, but engine needed 'rowing' through the gearbox, Dsi engine so relaxed, rolling in 5th gear.

Valve / Induction roar pronounced in GE 16 valve, GD so quiet in comparison.

I bought the Dsi Car, in my opinion th enew Jazz would be a better Car with the Dsi engine installed.

Expect to see this happen when the Jazz hybrid goes on sale

[culzean]

I agree about i-DSi engine being more relaxed and easier to drive for everyday use than the VTEC.  I have driven both, and as a commuter car the i-DSi can have few rivals because you can afford to be really lazy with your gearchanging and the engine pulls sweetly and never complains. I have also driven long distances in the i-DSi (over 2000 miles around scotland in 2 weeks earlier this year) without feeling I needed more power.

Sure the VTEC has more power, but needs to be revved to access it, which puts fuel consumption up.

By the way - I have heard that the Jazz i-DSi engine is used by Honda for one of their larger outboard motors, probably because of its reliability and light weight.

[guest1128]

I have posted 1.34 i-DSi and 1.34 i-vtec engines' power and torque curves at this topic(its in Turkish but you can esily understand).

Up to 3500 rpm both engines produce equal torque and power, after opening second set of valves i-vtec dominates...

But there are many factors effecting economy and perfromance: I dont have any data if manual gearbox is the same or not in both types (ishift and CVT apparently different) or which design's aerodynamics coefficient is better. I know that GE is app. 10 kgs heavier.

I think that if GE i-vtec engine consumes less or equal to the i-DSi up to 3500 rpm, we can say   i-vtec is better.

[Geoffers]

Having had a GD and now running a GE, I can confirm that petrol consumption is very slighly better in the GE!
Bearing mind that the GE has much better low end acceleration and approx 20 more BHP from the same volume, I suppose this is hardly surprising.
My main reason for changing to the GE was the poor low end acceleration.

[E27006]

I have posted 1.34 i-DSi and 1.34 i-vtec engines' power and torque curves at this topic(its in Turkish but you can esily understand).
http://clubjazz.org/forum/jazz-ge-2009/jazz-1-34-engine-dyno-chart/

Up to 3500 rpm both engines produce equal torque and power, after opening second set of valves i-vtec dominates...

Those graphs are interesting,  point for point they match up to 3500 rpm.
Can you find a similar graph for 1.2 Ge Vtec superimposed on the 1.34 GD?

 

[guest1128]

I have posted 1.34 i-DSi and 1.34 i-vtec engines' power and torque curves at this topic(its in Turkish but you can esily understand).
http://clubjazz.org/forum/jazz-ge-2009/jazz-1-34-engine-dyno-chart/

Up to 3500 rpm both engines produce equal torque and power, after opening second set of valves i-vtec dominates...

Those graphs are interesting,  point for point they match up to 3500 rpm.
Can you find a similar graph for 1.2 Ge Vtec superimposed on the 1.34 GD?
 

Sorry, jazz  is and was only sold with 1.34 engine here, so only having 1.34 data 

[E27006]

Found some answer to my own question!

the two seem to match.
One other factor.

In the japanese 10.15 fuel consumption benchmarks,  smaller GE vtec gives 24km per liter,  bigger Ge vtec 19.6km per litre,  big difference!

Also peak power, small vtec 6000 rpm, bigger vtec 6600 rpm, what a screamer!