hey just noticed the new eclipse has a 3.8 litre SOHC Mivec producing 265hp, is that a 6G75? mitsi site didnt say.

average power from such a big motor with mivec.....

average power from such a big motor with mivec.....

What about delivery and torque though....

It would seem that way

yeah i was suprised at the low output, bet it could be really opened up

MIVEC isn't a performance feature any more, Evo aside. It's there to improve fuel consumption.

MIVEC isn't a performance feature any more, Evo aside. It's there to improve fuel consumption.

MIVEC like most variable lobe/variable valve timing arrangements does improve performance. By broadening the torque curve there's more power at lower rpm, in the mid-range and top end. At cruise MIVEC/VVT will improve fuel economy but at full stick may even burn more fuel. The 3.8ltr 6G75 MIVEC is rated 23kW more than the Aussie 380 and has the same triple CATS so will use more flat chat assuming similar rich A/F ratios.

Cheers,
Alan

hey just noticed the new eclipse has a 3.8 litre sohc mivec producing 265hp, is that a 6g75? Mitsi site didnt say.

dohc?

dohc?Nope. SOHC. Has a 10.5:1 compression ratio though.

Alan, I can appreciate that but they should've gotten much better power from if it's for performance. The Ford-designed 3.7L V6 in the Mazda CX-9, with DOHC & direct injection, makes 273HP at 6250rpm and 270 lb/ft at 4250rpm. The Eclipse makes 265HP @ 5750 RPM and 262 lb/ft at 4500rpm. Both have 6500rpm redlines. All the complexity of MIVEC and they couldn't get the same power as a fresh direct injection design?

Alan, I can appreciate that but they should've gotten much better power from if it's for performance. The Ford-designed 3.7L V6 in the Mazda CX-9, with DOHC & direct injection, makes 273HP at 6250rpm and 270 lb/ft at 4250rpm. The Eclipse makes 265HP @ 5750 RPM and 262 lb/ft at 4500rpm. Both have 6500rpm redlines. All the complexity of MIVEC and they couldn't get the same power as a fresh direct injection design?

Not utilising DOHC makes a fair difference though. And having MIVEC on sohc means that only one side (exhaust or inlet) is variable, similar to the VCT falcons of old.

My old EG5 Civic VTi, which had a D16Y, 1.6L SOHC VTEC, 9.3:1 compression, ran on 91RON, produced 81HP/L. The MIVEC 3.8 makes 70HP/L. This is 15 years later.

My old EG5 Civic VTi, which had a D16Y, 1.6L SOHC VTEC, 9.3:1 compression, ran on 91RON, produced 81HP/L. The MIVEC 3.8 makes 70HP/L. This is 15 years later.

However, most garden insects produce more Torque than the 1.6 Honda engines.

Nope. SOHC. Has a 10.5:1 compression ratio though.

Alan, I can appreciate that but they should've gotten much better power from if it's for performance. The Ford-designed 3.7L V6 in the Mazda CX-9, with DOHC & direct injection, makes 273HP at 6250rpm and 270 lb/ft at 4250rpm. The Eclipse makes 265HP @ 5750 RPM and 262 lb/ft at 4500rpm. Both have 6500rpm redlines. All the complexity of MIVEC and they couldn't get the same power as a fresh direct injection design?

The 3.8 MIVEC engine could produce much more quite easily. Our 380 should make about 200kw/270HP with the 2 manifold CATs removed, the cams moved and with the ECU flashed even more. Most likely the MIVEC version would make 25HP more given the same treatment. However manufacturers have a different agenda that varies from one to another. In fact many current engines are detuned much to the annoyance of those who developed/designed it. Why? Emissions, fuel economy, vibration and noise and harshness, warranty concerns(particularly drivetrain), engine useage across many platforms(car, light 4WD, heavy 4WD, pickup, light truck) etc.

Just looking at your example I would say the Mazda/Ford 3.7 was the underperformer of the two. Direct injection is an easy 10% extra HP without any loss of economy or extra emissions, and the engine is spinning 500rpm faster to make maximum power. For an engine of that size an extra 500rpm should equate to another 22HP. So to my thinking the Mazda should have made 305HP, so is below the 3.8 MIVEC just looking at it from HP alone(very dangerous, Porsche 3.8 = 350HP). 10 years ago the 3.0ltr Mitsubishi GDI (direct inj) made the same power as the Mazda.

The SOHC MIVEC system is pretty simple, basically mechanical, with electro hydraulic activation. Just your basic hot-rodding really taken to another level. Direct injection is very complex to get right and maintenance cost is very high, and there are many bits that will require regular(expensive) replacement. Think of comparison of maintenance/rebuilding a manual trans vs rebuild/replacement of double clutch semi-auto trans.

Cheers,
Alan