MK2 1.8

[Jonny671]

So, I've a 1.8.. And when accelerating its not bad, but when you get to about 3k it seems to open up and you can audibly hear a change in revs and it pulls harder.

Now, I've just been out in my workshop and theres a 1.8 Import MK2, and has a bulge on the left cam area and a little box and pipe on top of it.. The technician says this is Variable Valve Timing.

So I haven't got that box thing on my engine, what is it that happens at 3k in mine?

[Gizmo!]

The 3SGE engine in the MR2 I used to have had variable inlet pipes to let more air ir at higher revs, felt like a mini-VVT kick.

Wonder if the Mk2.5 engine has that?

edit: haha - Wikipedia's first picture on this page... http://en.wikipedia.org/wiki/Variable_length_intak...

Edited by Gizmo! on Wednesday 14th July 10:25

[Jonny671]

Ah, pictures!

This is basically what mine looks like..



Although as I understand it, from the crossover pipe going under that pipe its a 1.6 and mine is a 1.8.

This is what the Import in the workshop looks like;



See that box ontop of the intake cam?

(I think its called the intake cam and the right is the exhaust cam? )

[Gizmo!]

More wiki-ing: is yours a 99/2000 model?

http://en.wikipedia.org/wiki/Mazda_B_engine#BP-4W

[Jonny671]

Gizmo! said:

More wiki-ing: is yours a 99/2000 model?

http://en.wikipedia.org/wiki/Mazda_B_engine#BP-4W

Ah yes.

So mine has this Variable thing but its inside the head?

I still don't get it

[youngsyr]

The 99-00 have VICS (Variable Inertia Charging System), which as I understand it is a butterfly valve in each of the inlet runners that optimizes the flow of air into the engine. Whether that's the cause of your power surge or not I do not know.

http://en.wikipedia.org/wiki/Variable_length_intak...

[MX-5 Lazza]

Yours is a Mk2 - that import is a Mk2.5 which has VVT

It's normal for the power to pick up a bit around 3/4k rpm - Mazda did that deliberately to make it feel sportier.

[Jonny671]

youngsyr said:

The 99-00 have VICS (Variable Inertia Charging System), which as I understand it is a butterfly valve in each of the inlet runners that optimizes the flow of air into the engine. Whether that's the cause of your power surge or not I do not know.

http://en.wikipedia.org/wiki/Variable_length_intak...

So like the way it changes the intake manifold shape or something?

When the car is cold you get quite abit of the surge, when the car is warm though you notice it slightly less.

[youngsyr]

Jonny671 said:

youngsyr said:

The 99-00 have VICS (Variable Inertia Charging System), which as I understand it is a butterfly valve in each of the inlet runners that optimizes the flow of air into the engine. Whether that's the cause of your power surge or not I do not know.

http://en.wikipedia.org/wiki/Variable_length_intak...

So like the way it changes the intake manifold shape or something?

When the car is cold you get quite abit of the surge, when the car is warm though you notice it slightly less.

Having read the wiki link again, it seems that there are actually two sets of runners from the inlet manifold to the to the engine for each cylinder, with one set of runners being shorter than the other.

The butterfly valve controls which set of runners are used in any situation, so you get the benefit of longer runners (longer time for the charge to mix) when you need it.

I imagine the valve opens/shuts based on rpm and/or calculated engine load, so that could be a factor in the "surge" you're experiencing.

As others have said though, it's probably just that Mazda have optimised the engine's performance to give that surge. My 10 AE really picks up from around 3,000 rpm to 4,500 rpm and then the torque dies off. I'm trying to find ways to stop the power dropping off.

[sonarbell]

Hi Jonny

The Red car doesnt have VICS or VVT. The Green car has VICS and VVT. Doesnt matter if its an import or not.

Pre 99 NO VICS or VVT (Mk2)
99->01 VICS only (Mk2)
01->04? VICS and VVT (Mk2.5)

All 1.8's

Hope this helps

[Jonny671]

sonarbell said:

Hi Jonny

The Red car doesnt have VICS or VVT. The Green car has VICS and VVT. Doesnt matter if its an import or not.

Pre 99 NO VICS or VVT (Mk2)
99->01 VICS only (Mk2)
01->04? VICS and VVT (Mk2.5)

All 1.8's

Hope this helps

Thanks!

Although mine is a 1999.. So how would I tell if it has VICS? Is that what the change in revs is?

[sonarbell]

With VICS you have the bulgy type Inlet manifold. Notice how much larger the Inlet manifold is on the green car compared to the Red one ?

Max power isnt developed untill around 5250 rpm with VICS. (Approx 140 bhp)
VICS valve is actuated around 4500 rpm
As for expecting any torque.. Forget it !! (My NSU Quickly had more Torque)

All figures from memory but Im sure if they are far out someone will come along and correct me..

Edited by sonarbell on Wednesday 14th July 18:14

[Jonny671]

sonarbell said:

With VICS you have the bulgy type Inlet manifold. Notice how much larger the Inlet manifold is on the green car compared to the Red one ?

Max power isnt developed untill around 5250 rpm with VICS. (Approx 140 bhp)
VICS valve is actuated around 4500 rpm
As for expecting any torque.. Forget it !! (My NSU Quickly had more Torque)

All figures from memory but Im sure if they are far out someone will come along and correct me..

Edited by sonarbell on Wednesday 14th July 18:14

Ah right! Thanks very much.

I've got the larger bulge type inlet I think.. Will look tomorrow

5250rpm! Jesus, I usually change way before then when driving, normally.. Hooning obviously not

[sonarbell]

Its a pre-requisite for owning an MX5... "You drive it like you stole it" !!!

Your best friend is your Rev Limiter...!!

I dont often drive mine to the limiter but "it aint half fun when you do" !

At the bottom of a well known MX5 servicing company's list for standard servicing is ....."Red line it at regular intervals"..

"Nuff Said" ..

[MixxyMatosis]

Hasn't anyone told you? It's the flux capacitor.

[sonarbell]

The energy produced by "Mr Fusion" type reactor uses plutonium as the primary source of power for the Flux Capacitor and Time circuits
The "Mr. Fusion Home Energy Reactor" converts household waste to power the Flux Capacitor and Time circuits.

As you can see they are both Mr Fusion type converters but it depends on what year you are referring too.
A bit like whether you have VICS or VVT or neither..........Or a Torsen or a Viscous or just any old stuff..


Hmm rambling on a bit here me thinks !

[MX-5 Lazza]

It's a bit early to have had THAT much vodka isn't it SB?

[sonarbell]

Its never too early and Vodka isnt my thing.. Now Red wine or Brandy.......... Hic Burp

Edited by sonarbell on Saturday 17th July 22:57

[MX-5 Lazza]

Or?