Follow my progress with Wagonstein!

[91CavGT]

I'll be posting in this thread any updates I have for Wagonstein. For those that didn't see my other post, Wagonstein is a 1991 Chevrolet Cavalier station wagon. It has a built 3.1L V6 that's turbocharged which is not good for gas mileage, but the 5 speed transmission that was swapped into it does help. What really helps is the car has a full standalone Haltech computer!! :D I can program it to run however I want!!! :D


The 1st tank of gas was a baseline. Just to show how rough of a tune the car had on it.

14.6 mpg! 168 miles and 11.5 gallons of 93 octane gas


I just filled up tonight at the same gas station and the same gas pump. However, I have done some tuning to the car since the last tank of gas. I DID NOT touch the air/fuel mixture controls at all. I did however get the car to idle at 800 rpm instead of hunting for a 1200 rpm idle, I turned on closed loop operation (I can't believe it was turned off!!!), I lowered the coolant temp where the computer switches over from open loop to closed loop operation (it's at 140 degrees now, it was at 160 degrees), and I decreased the accelerator pump output at 0 rpm, 1500 rpm, and 3000 rpm.

20.2 mpg! 227 miles and 11.2 gallons of 93 octane gas!! :D


This is a huge improvement for not even touching the air/fuel maps!! Today I started looking at the ignition timing maps. While not under boost, the ignition timing is VERY conservative (no more than 30 degrees of advance while under light throttle and cruising) even though this motor has a compression ratio of 8.8:1 and I'm running 93 octane fuel!! Just in the last few hours I've advanced the timing as much as 10 degrees in some points of the power band. I'm going to keep advancing the timing till it either misses or I hear audible knock, at which point I'll back the timing off 3-5 degrees. Now, I'm not adjusting anything at all while the car is on boost, I'm only adjusting the settings that apply to the motor while it is under vacuum.


My goal is 25 mpg in town and 35 mpg on the highway, the ability to run a 13 second 1/4 mile with just changing tires, and be able to haul my wife and 2 kids somewhat comfortably along with cargo where ever we want to go.


I'll post results from my next tank of gas here.

[101mpg]

Good goals trying for a mixture of FE and usefulness. Keep us posted!

[91CavGT]

I filled up with gas tonight. Here are the results.........


250 miles driven
11.767 gallons of fuel used
21.25 mpg!


The mileage is still going in the right direction! This was once again with a few full throttle blasts for one reason or another. The only change I made from the last tank of gas to this one is advance the ignition timing under cruise and adjust the idle a bit better. Right now the car is running 37-42 degrees of advance at low load cruising speeds and 13-18 degrees of timing at idle.


I want to get a weaker wastegate actuator from a friend of mine so I can tune a "fuel economy" program. This will limit boost to 2-3 psi with a very slow buildup of boost. It will also be tuned to run on 87 octane. This combined should give me a bit more power off boost while still giving more power than stock while under boost. I'll keep the current program I'm working on as the "fun 93 octane" program. I need to wire up the electronic boost controller though to do this effectively. I also need to get a pair of 185/70/14 tires to put on the stock rims. Right now the car has 225/50/15 tires up front and 205/55/15 tires on the back. This also changes my gear ratio so it's running a couple hundred rpm higher on the highway.

So I'm thinking that the tire swap and the 87 octane tune should give me a 2-3 mpg increase over what I'm seeing now. Time will tell if this in fact is true.

[91CavGT]

Yet another update!


On this tank of gas the only changes to the tune were minor since it is starting to get close. After seeing at idle that the O2 correction was pegged at 20% decrease in fuel I leaned out idle air/fuel mixtures just a bit. There's still room for improvement though since the O2 correction now goes from 10% to 14% reduction in fuel. The biggest help I think though is that I lowered the engine off during deceleration from 2,000 rpm down to 1400 rpm. I can lower it more, but when the motor is cold, it tends to REALLY make the idle hunt since it revs up, but with zero throttle the computer kills the motor till rpms drop below 1400.


So, without further ado..........


275 miles on this tank of gas
12.138 gallons used
22.65 mpg!!


I'm now less then 2.5 mpg away from my goal of 25 mpg in town, yet the car still has not had a tune on the air/fuel maps!! Not only that, but the ar has wide 225/50/15 front tires and 205/55/15 rear tires. The stock tires are 185/70/14s. I'll be putting these back on the car later down the road. Traction will suffer, but overall gas mileage will increase and rpms on the highway will also decrease.

[theholycow]

Can't you have separate programs for cold vs. warm? In the cold program, DFCO could be 2000 rpm, and in the warm program it could be 1000.

For the tires, I don't share your prediction. According to http://www.miata.net/garage/tirecalc.html you're looking at these tiny differences:
.3 inch diameter
1 inch circumference
11 tire revolutions per mile
1.4% speedometer error, for .9mph difference at 60mph.

I think such a small gearing change won't affect FE much. The difference will be between aero improvement and RR consequence. Unless they are constructed significantly differently, the narrower tire at the same pressure should mean increased rolling resistance. I think at city speeds the RR will be more important than aero. If the narrower tire accepts much higher pressure then it will probably be better.

[91CavGT]

Can't you have separate programs for cold vs. warm? In the cold program, DFCO could be 2000 rpm, and in the warm program it could be 1000.

For the tires, I don't share your prediction. According to http://www.miata.net/garage/tirecalc.html you're looking at these tiny differences:
.3 inch diameter
1 inch circumference
11 tire revolutions per mile
1.4% speedometer error, for .9mph difference at 60mph.

I think such a small gearing change won't affect FE much. The difference will be between aero improvement and RR consequence. Unless they are constructed significantly differently, the narrower tire at the same pressure should mean increased rolling resistance. I think at city speeds the RR will be more important than aero. If the narrower tire accepts much higher pressure then it will probably be better.



Unfourtunately, there is one setting for DFCO. There is one primary ignition and one primary fuel map. From there, everything else is just a matter of another map to tell the computer how much ignition or fuel to give under differant circumstances. There is one setting for DFCO, one setting for accelerator pump at differant rpms(but not at differant temps), one coolant/fuel correction, one coolant/ignition correction, one IAT/fuel correction, and one IAT/ignition correction. There are a few other minor adjustments that can be made, but these are the major ones.


Yeah, I went to that exact same calculator after I made the last post. I thought it was a bigger differance but I guess not. More than likely, the tires on the car now are shorter than a typical 225/50/15 tire is and that is where the differance is coming from, but it will only be 100 - 200 rpm drop at 65 mph is all.


It was my understanding that a narrower tire would provide less RR than a wider tire because there is a smaller contat patch. I'm currently running 35 psi in the 225/50/15 tires. I'll have to look at the 185/70/14 tires that I have to see what their maximum psi rating is.

[theholycow]

Nope, I used to think that too, but having achy tired legs while bicycling made me open my mind and really read up on it. The contact patch is the same size no matter the width of the tire, as long as the pressure is the same. If you have 50 psi and 500 pounds on it, you'll have a 10 square inch contact patch whether the tire is an inch wide or ten inches wide (except, with such an extreme example, there will probably be measurable interference from sidewall stiffness too).

The contact patch changes shape, however; with a narrower tire it's longer. So, to have the longer contact patch, more of the sidewall has to deform. That's where rolling resistance comes from (there's also some RR from tread block deformation too).

Bicycling enthusiasts are very superstitious and very marketing-driven, to the point that misinformation infects even dependable data sources. As such, even the ones who aren't superstitious or marketing-driven believe the same stuff. Additionally, the ones who really dig in and learn the stuff still find that (in a bicycling context) the aerodynamic advantages outweigh the RR -- and also, on a bicycle the narrower tire is usually rated for higher pressure, so it ends up with equal or better RR anyway. On a car, that's not usually the case.

[91CavGT]

Wow, that is actually pretty logical when you really stop and think about it. Thanks!!

So, in short, if I can get some taller and narrower tires that will lower my highway rpms dramatically (it's at 2400 rpm at 65 mph now) AND I can run higher tire pressures then it would be beneficial to FE. Otherwise I won't see much if any increase.

[theholycow]

That's probably right. I don't know exactly how the RR drag plays off against gearing and aero drag issues, and I don't know exactly how much additional pressure would be required to make a narrower tire equal a wider tire's RR.

Since you already have all those tires mounted on wheels, I'd love if you could do some coastdown testing and put some numbers behind my understanding of the theories. With wheel fairings it would be possible to almost entirely eliminate any aero drag error from the RR measurement. However, that sounds like an awful lot of work and especially difficult to do scientifically and accurately, so umm.......yeah. :)

[theholycow]

Actually, just after posting that I realized it's probably easy to calculate the amount of pressure required for the same RR. All you have to do is figure the contact patch size and shape and have equal lengths.

Also, in your situation, you have different wheel sizes; I don't know how sidewall height affects RR, but I'd guess that lower sidewall height increases RR because the sidewall has to deform more sharply and closer to the rim. Argh! There's too many variables to do the experiment. We'd have to be working with the same brand/model tires on the same size rims at the same sidewall height with the same tread pattern and the same load and the same temperature and the same pressure and.......eek....there's no realistic way to get accurate results from this without a big budget and a lab.

[91CavGT]

Yet another update!!


I didn't do much at all to the program on this tank of fuel so FE gains are minimal, but gains were still had!


291 miles driven
12.51 gallons used
23.26 mpg


The only thing I did on this tank of fuel differant is I leaned out the air/fuel ratio during engine warm up on the Haltech. This greatly helped to stabilize the idle even more during engine warm up.


This weekend I'm getting a weaker wastegate actuator from a friend of mine. With this wastegate, I should be able to set the boost down to as low as 2-3 psi! This means that I'll be able to run 87 octane fuel. I'm also going to set it so that boost comes on VERY slowly so during normal driving I can be a bit more agressive on the throttle without having to worry if the car is in boost. I'm also borrowing a wideband air/fuel monitor. Weekend after this one another friend and I will be tuning the off boost maps for 87 octane.


Tires during the entire time so far have been set to 35 psi. Today right before I filled up with fuel I raised that to 45 psi(max on the tires is 51 psi). For this tank I believe this will probably be the only change. Although I might take out a bit more fuel during warm up since it still smells like it's pig rich.

[Powerstroke IN]

I'm loving the work you're doing man. I can't wait to try to tweak my Cherokee the way you are!

Here's a piece of advice. Ditch the gasoline motor and go diesel. I'm getting the same numbers in the city in an 8000 lb truck that'll do 0-60 in a non-scientific (one mississippi, two mississippi) 6 or 7 seconds on 35" mud terrains and an 11 second 1/4 mile. Get it up to(I don't know how I didn't get arrested) 160 MPH racing a motorcylce on the interstate. He didn;t want me to pass him, but I did it anyway. And it seats 6 average sized people somewhat comfortably and has room to pack around luggage for 15. Not to mention the fact that I've hooked up to a 53' trailer and pulled a CAT D-6R 50 miles. Diesel is the way to go, man!

[91CavGT]

I'm loving the work you're doing man. I can't wait to try to tweak my Cherokee the way you are!

Here's a piece of advice. Ditch the gasoline motor and go diesel. I'm getting the same numbers in the city in an 8000 lb truck that'll do 0-60 in a non-scientific (one mississippi, two mississippi) 6 or 7 seconds on 35" mud terrains and an 11 second 1/4 mile. Get it up to(I don't know how I didn't get arrested) 160 MPH racing a motorcylce on the interstate. He didn;t want me to pass him, but I did it anyway. And it seats 6 average sized people somewhat comfortably and has room to pack around luggage for 15. Not to mention the fact that I've hooked up to a 53' trailer and pulled a CAT D-6R 50 miles. Diesel is the way to go, man!


When this motor grenades, I would like to drop a diesel into it. I've been thinking about the VW 1.9L TDI motor. Small, fuel effecient, and can be modified to produce some tire smoking power!

[Powerstroke IN]

When this motor grenades, I would like to drop a diesel into it. I've been thinking about the VW 1.9L TDI motor. Small, fuel effecient, and can be modified to produce some tire smoking power!

That's a good way to go, but I would reccommend something with a little bit bigger block or less displacement. Diesels can be modified to add up to 50% more HP with nothing but tuning. My 7.3L Powerstroke came from the factory with 262 HP, and I have a chip with a tune good for +140 HP. I haven't really done my homework on the smaller diesel engines available, so I don't know what's out there. But, in my personal opinion, I would go with the smallest engine possible if going into a car. There are always ways to get a custom air/fuel curve, as well as shift points if automatic, so a motor as small as half a liter could easily propel a car your size. But, then again, the bigger the engine, the more powerful and the less "throttle" needed to acheive desired speed. Find a happy medium and I can help point you in the right direction as far as upgrades.

[91CavGT]

That's a good way to go, but I would reccommend something with a little bit bigger block or less displacement. Diesels can be modified to add up to 50% more HP with nothing but tuning. My 7.3L Powerstroke came from the factory with 262 HP, and I have a chip with a tune good for +140 HP. I haven't really done my homework on the smaller diesel engines available, so I don't know what's out there. But, in my personal opinion, I would go with the smallest engine possible if going into a car. There are always ways to get a custom air/fuel curve, as well as shift points if automatic, so a motor as small as half a liter could easily propel a car your size. But, then again, the bigger the engine, the more powerful and the less "throttle" needed to acheive desired speed. Find a happy medium and I can help point you in the right direction as far as upgrades.


The reason why I was looking at the 1.9L TDI motor is because it is one of the smallest readily available small 4 cylinder diesels that is realatively new. If money were no object I'd get the diesel motor from a new Smart car, but they aren't available in the States. It is a very light and VERY small motor (I think a 1.0L motor) that makes about 60 hp and 75 ft lbs but can be modded to put out over 100 hp and 125 ft lbs or so. With its light weight it would be a weight reduction compared to the iron block 3.1L turbo V6 in the wagon now.

I'm a School Bus Diesel mechanic. All of our engines in the busses are brand new and computer controlled, but I'm learning more about the older diesels and how easy it is to modify them and how more fuel effecient the older ones are than the newer ones.

[91CavGT]

I picked up a weaker wasegate actuator today. I'll be installing it soon so I'll be able to run 87 octane gas. Boost will be set to a maximum of only 2-3 psi.

I also picked up a wideband O2 sensor/gauge. Next weekend the car is getting a good tune put on it.


Hopefully these 2 items will increase FE by at least 1-2 mpg.

[91CavGT]

Here's a picture of Wagonstein. What would be some effective aero mods to this car? A grill block is out of the question.


http://i8.photobucket.com/albums/a11/91CavGT/renthousesealing066.jpg

[Powerstroke IN]

I'm not too sure about the real benefits, but I noticed a small increase when I put a wind deflector on the back of my Jeep. It directs wind flow down over your back window. I can post a link if anyone wants check it out and let me know if I'm right.

What also might help is to block the holes on your wheels to keep them from paddling the air. Thats what my super mileage team did and we saw dramatic results. I just don't know how effective it would be on a real car.

Then, of course, there's always a belly pan. You might also consider a front facia and side skirts to keep air from going under the car.

[Hateful]

I taped up my hubcaps a while back, but didn't do any testing. I had the open space around the wheel blocked with tape and foam board, but it was trying to come apart. I found an inner tube by the road and attached it with L brackets.Some here on the site have said that the skirts reduce mileage,but it works for me.http://www.gassavers.org/garage_images/wfbe93fdx85o3zi5de31.jpg

[Powerstroke IN]

We used the heat shrink wrap you use to seal windows. I think if you taped a few layers on with some clear packing tap and then shrank them you'd be safe. Plus it would actually be hard to notice. Appearance means a lot to me...

[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]

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!! :eek: 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!!!!! :eek: 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!:D

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]

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

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.

[Zukibot]

Aero-wise, the Wagonstein looks pretty "aero" to begin with.

Have you considered lowering it? What about a full undercarriage, light weight skid-plate?

[91CavGT]

Aero-wise, the Wagonstein looks pretty "aero" to begin with.

Have you considered lowering it? What about a full undercarriage, light weight skid-plate?

The car is already lowered. It's got Suspension Techniques springs up front (approximately 1.8" drop) and Moog Cargo springs in the rear that are designed for a 2 door Cavalier coupe(higher spring rate, but it rides lower than stock). In the front and rear there are adjustable Koni struts/shocks.


My 1st aero mod is going to be an undercarriage tray in the front and back (the middle is already really smooth). I've got an old bedliner sitting at my dad's house that I plan on using for this purpose.

[theholycow]

My 1st aero mod is going to be an undercarriage tray in the front and back (the middle is already really smooth). I've got an old bedliner sitting at my dad's house that I plan on using for this purpose.

That idea is AWESOME!!!!!!

Thank you so much. It hadn't occured to me but it should be pretty easy to find a discarded corrugated bedliner (I've seen them on the side of the highway), and it should make a great belly pan (or skid plate or whatever you want to call it) for our purposes, unless the corrugations ruin the aerodynamic benefit.

Corrugated plastic bedliners are stiffer than coroplast, big, lightweight, and won't do too much damage if they come loose. That's perfect.

Has anyone done a yarn test with a belly pan to see exactly where the air goes?

[91CavGT]

Well, I haven't done anything yet to improve FE on Wagonstein, but I did take it to a drag strip to see where it was sitting.


After several passes, the best of the night was a 9.4 @ 79 mph with a 2.4 60' time. This is in the 1/8th mile. The car just kept spinning the tires all through 1st and 2nd gear even with feathering the gas. :thumbdown: :mad:


Anyway, I've currently got 160 miles on this current tank of fuel and the gas gauge is not yet down to 1/2 a tank!!

[thornburg]

Corrugated plastic bedliners are stiffer than coroplast, big, lightweight, and won't do too much damage if they come loose. That's perfect.


LOL! I realize that you are talking about two totally different things, but you understand the Coroplast is short for Corrugated Plastic, right?

;)

[dosco]

LOL! I realize that you are talking about two totally different things, but you understand the Coroplast is short for Corrugated Plastic, right?

;)

Yeah, but Coroplast is more like "plastic cardboard" than the bedliner material is.

[theholycow]

LOL, that is kinda funny. I should have properly capitalized the 'c' in Coroplast.

[91CavGT]

Sorry I haven't updated this thread in a bit. I've lost my last 2 gas reciepts and I don't like to give information off the top of my head for stuff like this. So anyway, on to my most recent gas log.


286 miles on this tank of fuel
11.568 gallons used
24.72 mpg



I have a feeling that there are 2 reasons for my sudden spike in mileage.

1. I have started letting the engine rev higher before shifting. The cam in this engine has a very noticeable increase in power at around 3,000 rpm. Here recently I have been shifting the car at around 3,000 to 3,500 rpm instead of 2,000 to 2,500 rpm.

2. Outside temps have increased around here and I am suspecting the tempurature of the fuel is really increasing, especially when the fuel tank gets low. I suspect this for several reasons. One of which happened today. At the end of my afternoon commute I was looking for a gas station when I noticed the car try to stall when I got on the throttle. This got worse VERY quickly and I coasted in to a gas station with the motor not running and still 2 gallons of fuel left in the tank (I have driven this car without this happening in cooler weather down to only 1 gallon of gas remaining). I believe vapor lock occured today. As soon as I filled up with gas, the car started up and drove with no problems (I kept the hood up on the car the entire time I was filling up). Both of my fuel lines under the hood come within 1" of my exhaust downpipe. I have wrapped the down pipe in header wrap, and it helped, but I believe I now have to wrap the fuel lines in something as well to keep them cooler so this does not occur again. I like the increase in FE, but I have no way of controlling the tempurature. Does anyone have any ideas on this? Does anyone know the vaporization temp of gasoline?

Hmmmm...... I have seen oil cooler thermostats that will not send any oil to the cooler until the oil reaches 180 degrees. I have 2 extra oil coolers laying around, but I think 180 degrees may be too hot to work.

[DRW]

IIRC gasoline vaporizes around 150*F.
If you're trying to heat the fuel, using the upper radiator hose for a heat source to is much more controllable.

[trautotuning]

Yes but gas vaporizes at 150 degrees without any pressure

Because it is pressurized in the fuel line it can actually be heated more (lets say 180 degrees) and as soon as it squirts out the injectors it completely vaporizes because it looses all the pressure.

I have always been in the school of thought that heating the fuel is probably the best thing you can do in FE, just that nobody has really tested it because, well, it can explode if something goes wrong ?!? haha