Jazz VTi-S GD3 DOHC or SOHC

[noobie90]

I was doing some research on the jazz I'm about to buy and just wanted to know if the engine is a DOHC or a SOHC.

I had a look of redbook and it says that it is a DOHC, is this correct?

Thanks, noobie90

[zco]

sohc champ

[Tai]

no jazz comes in DOHC from factory.

SOCK ONLY.

[mars_panas]

as above

[noobie90]

still confused lol, getting two answers...

[fillit]

SOHC only :)

[ss-rotel]

the 1.5 is SOHC L15A engine, with VTEC on the exhaust side., basically the car runs 12v until about 3.5K-4K RPM then it's 16v. The "smaller" exhaust side makes the hot gas flow faster @ low RPM. Pretty much like a small turbo, or when you put your finger over a house, the smaller the hole, the faster the water/gas moves, until the small hole becomes a restriction.

[redmugenjazz]

the jazz vtec work in a way which the second lobe engages a second valve at 2560 (from memory) rpm it increases flow at higher rpm. preety much at low rpm u would want a less air going in and out to maintain fuel economy and more flow at higher rpm (hence the vtec) will increase flow by the activating the additonal valve on the head. the jazz only had 2 lobes on the cam shaft, so it not real vtec where u have a third 'agressive' cam lobe lobe for activating high lift cam profile. u may hear a crossover at 5500 but its just a dual runners opening up - hence to increase airflow even more at high rpms.

[ss-rotel]

Under vtec, honda has 2-3 different technologies under the same name... sooo...

I'm sure it's 4400rpm thou... and technically, you dont want less air in the chamber, you what the air to move faster. SOOO... with 1x small port open over 2x small parts open, the air/gas will travel 2x faster out the side of the head with 1 over 2 ports open. This extra velocity will create a slightly more vacum in the headers, and usually there's a slight overlap in the cam, so @ some stage both the intake and exhuast valves a slightly open, this vacum sucks in an amount of extra air/fuel, over and above the down stroke of the piston. more fuel/air, bigger boom, more power torque

At some stage this smaller single port will start to restrict the flow, so the 2nd port opens, problem sovled

Anyway...

From memory, you want less overlap @ High RPM, (and more value lift/less duration, (?)), and more @ lower RPM. one way to do this is to hydroically change timing of the cams. This only really works on a dual cam engine...

How that vtec you've mentioned works, a hydrolic solinoid pushes the cams ofset until the second cam ground engages with different duration and lift. This works with any overhead cam engine.

I'm sure you'll find the first Vtec engine is a SOHC engine, and the small L series engines are based on this from what i can see.

[ss-rotel]

and i'm pretty sure that the acutator is on a pin that pops into place on the secondary lifter, so it can open the valve... like i said, there's a number of different versions pen under the vtech badge