Saturn TDI nose job... - Page 4 - Fuel Economy, Hypermiling, EcoModding News and Forum

Craig · 03-23-2011, 07:51 PM

Filled it up again today, and got 60.92 mpg, so I finally was able to back up my 60+ figure two fillups in a row!

I'm going to play with the nose job some more; need to pick up some coroplast and make a belly pan under the nose to see what kind of improvement that will make. I'm sure there is a good deal of turbulence that can be smoothed out.

Craig · 04-15-2011, 09:00 PM

I made a belly pan to go under the nose, and it helped a bit. Took a trip to Rockland, and it got 64 mpg...would have done even better, but I was following my uncle on the return trip, and he was doing 75 mph most of the time. The next fillup netted 60.6 mpg, but I ran some errands and got caught in some construction traffic a couple of times this week, which I'm sure didn't help my mileage. Still, I'm getting better at squeezing more fuel mileage out of it, and having a good time doing it!

After I run this for awhile, I'm going to build a belly pan to go between the rear suspension and under the rear bumper and see how that works. I'm also looking at some of the smooth wheel cover ideas, as I have a complete set of Saturn wheel covers that would be ideal for this project.

cfg83 · 04-16-2011, 12:50 AM

Craig -

I am looking forward to pictures of the belly pan. MPG racers will fear you!

CarloSW2

brihoo2k · 04-16-2011, 10:04 AM

Very impressive build. I read the entire thread both here and the tdi forums. I have a 1500 vw diesel in my garage I think maybe I'll be on the lookout for a Saturn instead of putting it back into an 81 rabbit. It may not have the power of the tdi but I think it would have enough torque to do the job. Also I think I have the perfect thing to make an adapter plate for the transmission (some 1/2" aluminum plate). You have some mad skills my friend.

COcyclist · 04-16-2011, 10:59 AM

Quote:

Originally Posted by Craig

I made a belly pan to go under the nose, and it helped a bit. Took a trip to Rockland, and it got 64 mpg...would have done even better, but I was following my uncle on the return trip, and he was doing 75 mph most of the time. The next fillup netted 60.6 mpg, but I ran some errands and got caught in some construction traffic a couple of times this week, which I'm sure didn't help my mileage. Still, I'm getting better at squeezing more fuel mileage out of it, and having a good time doing it!

After I run this for awhile, I'm going to build a belly pan to go between the rear suspension and under the rear bumper and see how that works. I'm also looking at some of the smooth wheel cover ideas, as I have a complete set of Saturn wheel covers that would be ideal for this project.

Nice! The belly pan helped me get into the 60s for mpg for some highway trips (according to the ScanGuage). Like you, I couldn't keep it there for the whole tank but my tank averages have been better. If you do a partial rear pan, make sure the leading edge is tucked up tight so air doesn't get in. I was doing a slow speed test of v1.0 mock-up belly pan and a gust of wind hit and sucked it right off the bottom of the car. Version 2.0 has been tested at triple digit speeds with no problems. Diesel exhaust is cool enough that I have coroplast in direct contact with the exhaust. I have pictures in my album.

Do you think the Saturn is more aero than the Jetta? Less frontal area? Will you swap in a taller 5th gear at some point?

Craig · 04-17-2011, 07:15 PM

Hope this turns out ok, had to resize it to make it work. Anyways, here it is! I ended up making it in three pieces, with the third (center) piece easily removable so I can change the oil filter. I made up some brackets to secure the inboard part of the belly pans, and the outer ones use those plastic push pins to secure it around the nose. You can see where the chin spoiler ducts air up into the intercooler and radiator - diesels tend to run cooler, so I haven't experienced any cooling problems.

I'm guessing the Saturn might have a slight aerodynamic edge over the Jetta...I know it's a lot lighter, weighing in at 2480 lbs with 10 gallons of fuel and a second battery in the trunk. The 195-60 15 tires are a lot taller than the Jetta tires, making the overall gear ratios taller across the board. 60 mph = 2000 rpm with this car, although it would be really nice if I had a six speed to drop into!

Craig · 05-07-2011, 06:35 PM

My mileage figures continue to improve...been getting 62-63 mpg on a regular basis with the warm weather we are now getting. Yesterday I hit a new all-time high of 65.31 mpg, so I was VERY happy about that!

I ran over a tire carcass on I-95 a couple weeks back that took a big bite out of the belly pan and dislodged the rear bumper cover. I was able to remove the cover and beat all the mounting points back into shape so I could install it properly, and had to replace the drivers side belly pan with a spare piece of corrugated plastic. Haven't been able to find any locally, so I'm hoping they will have an election soon so I can scam a few political signs...

brihoo2k · 05-23-2011, 02:46 AM

Well I've gone and done it. I bought a 94 Saturn SL1 from an ad on Craigslist. It has the ever so famous cracked head that most of the sohc engines seem to get I mentioned to the wife about making the switch over to the VW diesel. She asked how long it would take? I told most of the summer (really I think I could do it in less time but then if it didn't take less time then it would get thrown in my face)

. Her reply was that's too long just fix it. I might fix it but it sure is tempting to start the switch over to diesel and start burning svo in it.