Low end torque

[JRMichler]

Originally Posted by Kodak

My engine can do 45 mph in 5th comfortably at 1500 rpm. Any lower and a mild low vibration tells me urges me to downshift.

Mine also has the 3.73 rear axle ratio. That mild vibration is a lot more noticeable at 700 RPM, but it doesn't seem to hurt anything.

[renault_megane_dci]

Longer inlet tracts helps but lenght and diameter needs to be tuned so not really practical for DIYer !

[Ladogaboy]

A larger 1st gear would could also help, since I'm sure you wouldn't want a lower geared differential.

[bhazard]

Originally Posted by Patrick

Move the timing belt on the cam pulley a tooth or two?

This is not a good idea at all. Most of the time one tooth can be 8 degrees or more and can mean the difference between the engine running at all or not. And then theres the interference part of it.

This is why theres adjustable cam gears. Not sure if the Atlas has a big aftermarket or not. Even then theres the VVT to deal with. In this case some sort of tuner would probably take the role of the cam gears.

Originally Posted by Ecky

I'd suggest advancing the ignition timing 1-2°. I've read that (on Hondas anyway) every degree advanced you move on ignition timing moves the torque curve down about 300rpm. Go too far and you'll start getting predetonation, but typically 1-2° is safe. You'll hear it if there's predetonation, it generally sounds something like marbles dropped on glass.

To advance ignition timing, first make a line on your distributor and motor at the stock setting (often 16°) and the turn the distributor slightly. The direction that makes idle go up is advancing.

If you have a timing light, the flywheel has markings for stock, -2° and +2° usually.

Sorry, but an extremely moot post. Im not sure if distributors were even used this century. Ignition timing is completely controlled by the ECU.

Originally Posted by JRMichler

Mine also has the 3.73 rear axle ratio. That mild vibration is a lot more noticeable at 700 RPM, but it doesn't seem to hurt anything.

I would be afraid of the main bearings being beat to bits lugging that low. I could be wrong though.

[JRMichler]

Some time ago I calculated power to overcome estimated aerodynamic drag plus rolling resistance plus driveline friction plus accessory losses, estimated the engine efficiency, and used those numbers to get a theoretical estimate of gas mileage. I convinced myself that the 2.8 L is a very efficient engine.

Then I looked at the effect of wind on gas mileage. And the effect of driving habits.

I am convinced that I can get significant further improvements in MPG by aerodynamics, specifically air dam with belly pan. Possibly also wheel covers and wheel well skirts. But not by modifying the engine.

I need a better air dam anyway. The factory one is barely held on with Gorilla tape and wire ties after plowing through too many snowbanks.

[Ecky]

Originally Posted by bhazard

Sorry, but an extremely moot post. Im not sure if distributors were even used this century. Ignition timing is completely controlled by the ECU.

My apologies, I'm not familiar with most domestic engines.

I believe Honda continued to use distributors on some of their smaller engines until as late as 2002 in the 'states, and (maybe?) 2007 in Asia, and I thought that typically American automakers were a little slower to adopt technologies.

[Ladogaboy]

I would say that timing adjustments are still very valid, regardless of whether they are controlled by a distributor or the car's ECU. Granted, all you need for timing adjustments with a distributor are a few basic tools, a timing gun, and maybe a friend. However, there are many open source tuning programs available that will allow you to adjust almost every aspect of your car's ECU, including timing advance.

[Frank Lee]

Wouldn't the optimum timing be the same regardless of whether you're trying to boost low end torque or not (especially with knock-sensor equipped systems)?

[Ecky]

Originally Posted by Frank Lee

Wouldn't the optimum timing be the same regardless of whether you're trying to boost low end torque or not (especially with knock-sensor equipped systems)?

It would, but do modern ECUs advance engine timing up to the very edge of where predetonation is detected, or do they following maps and retard if the knock sensor goes off?

[Ladogaboy]

Originally Posted by Frank Lee

Wouldn't the optimum timing be the same regardless of whether you're trying to boost low end torque or not (especially with knock-sensor equipped systems)?

It would; however, most manufacturers "dumb down" the timing to be on the safe side. It can *usually* be increased safely by at least a couple of degrees, but yes, there should be knock detection. I can't speak for all cars, but my car has two timing maps (one standard and one for when knock is detected). You'd really have to crack the ECU's coding to know for sure. I'd recommend checking online forums for people with similar cars who might have already messed around with the ECU.