Follow my progress with Wagonstein!

[91CavGT]

There is already a rear dam of sorts on top of the car that directs a small amount of air down over the back window. It came that way from the factory.

I have thought about smoothing the wheels on the outside, but I'm debating right now as to which set of wheels it would be easier to do that to.

[Powerstroke IN]

Originally Posted by 91CavGT

There is already a rear dam of sorts on top of the car that directs a small amount of air down over the back window. It came that way from the factory.

I have thought about smoothing the wheels on the outside, but I'm debating right now as to which set of wheels it would be easier to do that to.

My mom just got new tires, so I used her car to experiment on. The best possible way to do it is to tape the plastic to the inside of the rim of the wheel and then mount the tire from the back side. That way there aren't any issues with tape coming off and the plastic will stay as long as the tire remains on the rim. If you wind up using heat shrink wrap, make sure you shrink it slowly and evenly from the center outwards. If it happens to tear, just put a peice of packing tape on it immediately. Once you have it shrunk, cut a little hole near the hub and tape the plastic to the wheel. Just keep doing that in a circle aroung your lug holes/center cap. Easy as pie.

What are your options as far as wheels? I personally would go with the lightest possible that still apeals to you visually.

[91CavGT]

I finally got the car tuned last night. It's not a perfect tune, but it is MUCH better than what it was before.


After I got the wideband air/fuel setup working, I was amazed to see an air/fuel ratio of 10.5:1 at idle!! I then drove around slowly (normal cruise speed and throttle input) only to see air/fuel ratios ranging from a low of 9.5:1 to as high as 12.5:1!!!!! It's no wonder why the computer was pulling 20% fuel on the O2 correction!!


So after about 2 hours of tuning, it now is at about 14.3:1 at idle and it ranges from a low of 13.4:1 to 15.0:1 while cruising depending on the load put on the motor. The car runs MUCH smoother now, but a bad downfall is that it also runs MUCH hotter now. It really shows how lousy the current radiator is.


Luckily for me though, last night after I finished tuning, I picked up a nice dual core/dual pass aluminum radiator from a friend of mine!! This radiator kept his 400+ hp Cavalier cool so it should do the same for mine. I'm letting the car cool down now so I can go out to my garage and change it out tonight.


So, anybody want to take a stab at how much this tune will raise the FE of this wagon? My previous best tank was just over 23 mpg. I think it will raise it up past my goal of 25 mpg to around 26-27 mpg.

[91CavGT]

Tuning is now complete!! Tonight, for the first time in 4 years, Wagonstein has a full tank of 87 octane gas! Yes, the turbocharged beast has a tight noose around it's neck. In order to prevent the built motor from tearing itself apart and to improve FE, I did the following things;

Pulled out 2 degrees of ignition timing everywhere (this puts timing back to stock)

Lowered the rev limit from 6,000 rpm to 3,000 rpm. Top speed is now 80 mph

Set maximum boost level in the computer to 2 psi

Adjusted the wastegate actuator so it holds the wastegate flapper open at all times


With the cammed 3.2L V6 pulling around a 2800 pound car, I can keep the revs down low, stay out of boost, and still get up and move faster than traffic if need be. And since the highest speed limit where I drive is 70 mph, having an 80 mph top speed doesn't hinder me at all.


Current mileage on the car is 112331 miles. I'll post back in about a week and we'll see if and/or how much FE has increased.

[91CavGT]

I just filled up with gas again. Mileage at fillup was 112630 which means there was 299 miles on this tank of fuel. 12.297 gallons of 87 octane gas was pumped in giving a grand total of 24.3 mpg!

Now, some explanation is needed here. Yes fuel mileage did go up but not nearly as far as I had hoped and there is a reason for that. When I retuned the car, I did not touch any maps dealing with cold start. However, because everything else got leaned out and the cold start map changes fuel by a percent of what your normal idle speed uses, it effected it. Basically, the car was a MASSIVE pain to start. So, at 1/2 a tank of gas left I adjusted the coolant/fuel map to enrichen the mixture a good bit till coolant temps reached about 128 degrees. Unfourtunately, I should not have changed that map. I should have changed the fuel prime map. This is a map that allows an increase of fuel only at startup, adjustments are every 4 seconds, and it can be adjusted up to 48 seconds after start up. I just got through readjusting everything to how it should be.

The good news is at 1/2 tank of gas, the car had 175 miles on it!! The previous best at 1/2 a tank(the car got 23.3 mpg on that tank) was 145 miles.

This weekend I'm heading out of town so I'm gonna hit the highway with Wagonstein and track it's highway mileage! I'm hoping for somewhere between 30-35 mpg.

[91CavGT]

I'm back from the highway trip. Gas mileage was not as high as I had hoped, but it's not super bad either.


I topped off with gas on my way out at a gas station I've never been to before. Gas mileage dropped a bit because I had to drive 20 miles to get to a doctor appointment on time, but I was bookin it to get there.

132 miles
5.556 gallons to fill up
23.75 mpg


For the highway trip, I drove 220 miles one way to get to my destination. The very last 4 miles I had to go 20 mph down a very bumpy dirt road. For the 15 miles prior to that, there was some VERY nice twisty hilly roads that I couldn't help myself. Wagonstein held the corners with confidence!! On the way to my destination, I was averaging 60 mph with a 15 mph headwind. On the way back home, I had a light side wind but I averaged a faster 70 mph. Driver and passenger windows were open all the way.


317 miles
11.855 gallons
26.73 mpg

[91CavGT]

As a strange side note, I've got almost 200 miles (193 miles to be exact) on this tank of gas as of right now the gas gauge is showing just over 1/2 a tank of fuel!! I'm starting to think that this car gets better gas mileage at higher highway speeds than slower highway speeds. My previous 91 Cavalier was the same way (it got better gas mileage at 80 mph than it did at 60 mph).

[91CavGT]

The results are in.


328 miles
11.876 gallons used
27.62 mpg!!


160 miles of this tank was spent on the highway at 70-75 mph. 168 miles of this tank was my normal daily commute.

[Zukibot]

I really like the Wagonstein and your experiments. Car has character!

I do wonder if keeping the stock boost could be more efficient though... Have you ever tried to obtain that needed octane for the turbo by mixing 87 octane (reg. unleaded E10 - gasohol) with E85 (ethanol)?

[91CavGT]

Originally Posted by Zukibot

I really like the Wagonstein and your experiments. Car has character!

I do wonder if keeping the stock boost could be more efficient though... Have you ever tried to obtain that needed octane for the turbo by mixing 87 octane (reg. unleaded E10 - gasohol) with E85 (ethanol)?

Thanx!!


Well, the stock boost level was around 7 psi with the VERY tiny T25 stock turbo. This turbo is MUCH larger than the stock one (it's a T3/T04E hybrid) so around 3 psi on this turbo is equal to 7 psi on the stock turbo. E85 gas is not available in this area, but I have been toying with the idea of adding water injection. Properly tuned, I could run 87 octane fuel and set the maximum boost level to around 5-7 psi.

One thing to keep in mind too though is that as boost pressure comes on, the air/fuel ratio dips down to an average of 11.5:1 which is pretty rich. I have the wastegate setup right now so that boost comes on VERY slowly. This makes it harder to get into boost which makes it easier to get better FE. Currently, the car gets into boost at about 2400 rpm and 3 psi of boost is seen at about 3300 rpm. With the wastegate set for maximum response and minimal lag, the car gets into boost at about 1800 rpm and has full boost (9 psi on 93 octane) by 2800 rpm.