26.2 mpg Toyota Previa. Go Golden Egg!

[Grim]

Hard to say if it would help or hurt. I will say this. I also have a 86 4Runner with a 22re (2.4l like the previa). It is on 33's spinning 4.88 gears has a lumpy engine builder "RV" cam. It gets better mpg then the SC Previa.

As the displacement grows the "sweet spot" comes at a lower and lower RPM. I know my 4Runner likes to spin between 2800-3300 RPM. Thats where I can squeeze 24mpg out of it despite the 33's. Not only does it get better MPG it is faster 0-40.

The N/A Previa was geared to spin about the same RPM at the same speeds. (think they came with 4.10 gears maybe a 4.30) and people all over the place claim 24-26mpg and up to 28mpg with the manual. The complaint was on the hwy they topped out about 70mph and felt very labored. The supercharger let them run the 3.73 and improve the top end. at 70 my SC still feels peppy. The bottom end and take off was improved with the clutched super charger giving about 6psi of boost but it gets significantly worse MPG.


I wonder how it would do to split the difference and run say a 3.90. That is a common gear to the Supras and I think they run a 7.5 ring like the Previa so it should be a usable R&P. I wonder if the 2wd 4cyl trucks ran a 3.90. That might be a plug and play pig.

Somebody on Toyota nation or Toyota van people site stuck a NA diff in a SC to improve towing. Said it took the labored feeling out of it. He had to swap out the tone ring to get the ECM and speedo happy. He ran a bit taller tire on the rear as well to slow it down some on the hwy.

[comptiger5000]

If the cam is lumpy, it is often set up for high RPM power. However, an RV cam is usually meant for low end. Do you know what RPM range it's set up for?

3.90 gearing would probably be a good compromise, and might be enough to get the engine closer to its powerband, improving mpg.

[Grim]

Doesn't have the RPM listed on the site. just the lift and duration .
268° .425

Never idled "smooth" but it will idle at 400rpm if I crank down on it. Had the injectors cleaned and flowed, the motor was balanced and runs smooth at high rpm. People are surprised at how good it pulls especially with 33x12.5s under it.

I need to find out it Toy did the the same thing on this van as they did on the trucks. There is a 4cyl and a 6cyl 3rd The 6 cyl having a beefed up pig with a longer pinion for better support. The Turbo 4cyclinders also got the beefed up 3rd. The way the junk yards are running down here I can probably pick up a 390 for $50 once I figure out what will fit.

I have a 4.10 from the 4runner when I stuck the TRD elocker in it but it is a 8 inch 4cyl. I think the vans got the 7.5s so I do not know if it will fit.

[George Tyler]

As I menioned in another thread, I ran for the last 2 weeks with no SADS shaft, just put it back today. the van seems to go much better without it as far as acceleration goes, and consumption droped 1.7L/100km. I looked for a way to mount the alternator on the engine, but it's not easy. maybe better to mount the alternator on the diff, and only energise it when the throttle is closed? or when the brake lights are on as someone said, lets you only use waist energy. ran around town, and it's summer here, 28 deg C, no sign of overheating. with no fan