Lets hear ALL of your creative ideas about how to improve the fuel efficiency of the 2.8L Fiero. Such as special internal engine parts, lowering the coefficient of drag, synthetic oil, etc.....

I am aware of fuel efficient driving habits and giving the car a tuneup so it would be helpful to mention other ideas.

Many people on this forum have been very creative with their engine swaps and mods so lets see if we can apply that creativity to improving the efficiency of the Fiero.

Minor to crazy, I would be interested in all ideas.

I rebuilt my 2.8 to a .40 over 3.1, yielding a final displacement of 3.2L. I used a Crane 2030 cam and ported the exhaust manifolds but other than that I didn't do anything. At 70mph average speeds I get 28-31 MPG depending on whether the gas has ethanol or not (pure gasoline gives me better mileage). Around town I get low to mid 20's. My tranny is a Getrag 5spd with Synchromesh.

JazzMan

Newer ECM (there's a thread about it here somewhere).

If it is an automatic you drop in the 4T60 transmission and do a 7730 ECM upgrade. This is Darth Fiero's (Ryan) thread on the 7730 ECM upgrade https://www.fiero.nl/forum/Forum2/HTML/079574.html

Do not port anything, get a cam optimized for low end, roller rockers, raise compression ratio.

Do not port anything ?? not even the exaust manifolds ?

You definitely want to port the exhaust manifolds. However, don't port them where the flange is welded to the tubes, instead just port them where the stub tubes are welded to the main tube. That's a significant restriction. Porting only those mean no need to get any welding done.

JazzMan

I didn't think about roller rockers...Darth's ECM idea sounds good but I wonder if it will help mpg with a getrag.


Awesome ideas, keep em coming!

On an auto car upgrading the trans to a 440T4 will yeild about 35 mpg vs. the th125's 25 mpg

Otherwise, port the intake, exhaust, and a power pulley kit from Rodney Dickman, upgrade the alternator to the CS130

Not sure what other people here might think of this , but you could try experimenting with the ignition timing.

My gas mileage with my '86 GT is bad (14 MPG) even though it appears to run fine. A few days ago I re-timed the engine "by ear" like I used to do years ago with my high performance V8s. Yes, I realize those V8s of mine didn't have ECMs etc, but I've wanted to try this for awhile.

So far the 2.8 is running better with more advanced timing than the manual calls for (factory is 10 degrees BTDC), and no "rattling" is occurring during hard acceleration (running Regular gas). It remains to be seen if my mileage improves, but I'm confident it won't be any worse.

I’ve also disconnected the cold start injector. Don’t need it, even up here in the winter on the coast of the great white north.

[This message has been edited by Patrick (edited 03-10-2009).]

Jazzman is correct ,,BUT for peak performance the weld must be removed ,, roller rockers will help a tiny bit more efficient I like them ,a cam NO! the 2.8 V6 can be a good performer with top MPG for a V6 by simply doing a great port job,, the welds are very restrictive,Yes I know thew hassle of the weld job(mine was terrible ) I will never have the knowledge of jazzman ,,but I know porting I ported many racing scooter a much more difficult job to perform correctly ,, the manifolds on the V6 are works of art for the engine compared to many other cars
you can make the V6 produce 25 ,26 mpg around town with a 4 speed,,you ,ll never get the horse power of your fantasies but top M. P. G. can be produced more later
Bat attack !!!

[This message has been edited by uhlanstan (edited 03-13-2009).]

To improve you mileage you want to make sure your tires are properly inflated. This reduces the rolling resistance. You can even keep them a little higher than recommended, but this will cause a harsher ride and wear the center of the tires out more quickly.
The best way to improve you car's mileage is to modify how you drive. That means no hot rodding, no jack rabbit starts, no high speed runs, no hard braking, etc. Don't leave your car idling to warm up. Drive it to warm it up. Speed up slowly and try to coast to a stop. If you are going to be stopped for more than 30 seconds, shut the engine off. Maintain a constant speed on the highway and keep to the speed limit or below. Remove all excess weight from the car and keep the exterior clean and waxed. Make sure you change you oil when recommended and keep your engine in tune.
If you want more tips on saving gas do a Google search for Hypermiling, but beware of some of their practices as they can be unsafe.

88 2.8/ getrag. 34 mpg highway at 70 mph. Around town, 16 usually. Why the difference? simple. TEMPERATURE. the car will not warm up even with a 195 tstat unitl I am at my destination in local driving.
I live right off a highway, on my 12 mi highway ride to work, I am not at full operating temp til I'm 3/4 of the way there.
engine mods are .030 over 9.1 pistons, cam, sprint headers, ss tulip valves, porting on intake and exhaust, timing set at 12 degrees.
Car will warm up quick sitting there, but any motion keeps the temps down. this is the 2nd fiero I;ve had that I have trouble getting to temp, just the limited flow thru the heatr core tubes and the minimal flow thru the tubes under the car seems to be enough to keep things cool. Once it is up to temp it will stay there, but on the low side.
From my multiple aldl logs, it is all temp related, the motor runs way more efficiently at 195 than at 185, just getting there is the issue for me, and would really help the local driving mpg.
So given a relatively stock motor, without tearing it down, do the exhaust log restrictions, and make sure your car is running at temp and gets there quickly.
as a ref, my 86 2,8 all stock with the 4 spd isuzu would still hit 28 mpg @ 70 on the same long hiway trips, the differrence there would soley be the 5th gear od the getrag has, so the internal engine mods I would say are a bit of a wash as to benfit for MPG.
the benefit for performance is another issue, but that isn;t the point of this thread.,

hey patrick i had same problem w/my 86 gt it was badly out of timing.i timed it the same way (by ear) and went from 12-14 mpg to 18-23 mpg depending on driving style. also i have a hypertech thermomaster chip and 160 degree thermostat but the chip and thermo did not significantly change the mileage (unless you count my foot getting much heavier/what a difference).

quote Originally posted by rdnkbobby: hey patrick i had same problem w/my 86 gt it was badly out of timing.i timed it the same way (by ear) and went from 12-14 mpg to 18-23 mpg depending on driving style.

Bobby, thanks for the info. I'll be looking forward to working out my mileage in the next week or so to see if it improves.

I've been a member here almost since day one, and I can probably count on the fingers of one hand the number of times I've read about the 2.8 in a Fiero being timed "by ear". I'm expecting someone to give me hell soon and state it shouldn't be attempted.

quote Originally posted by Patrick: Bobby, thanks for the info. I'll be looking forward to working out my mileage in the next week or so to see if it improves. I've been a member here almost since day one, and I can probably count on the fingers of one hand the number of times I've read about the 2.8 in a Fiero being timed "by ear". I'm expecting someone to give me hell soon and state it shouldn't be attempted.

Hands Patrick the one aforementioned hell. (well, some had to, and he did ask politely)

I've timed hundreds of motors by ear. after you learn how to do it, it is fine. not that everyone can or should do it, but nothing wrong with it with stock motors.

quote Originally posted by Alibi: Otherwise, port the intake, exhaust, and a power pulley kit from Rodney Dickman, upgrade the alternator to the CS130

Will porting the intake help mpg? I have wondered about this myself but someone else said not to port anything. I myself have the sprint manifold from the fiero store and have noticed that they help my mpg but I am not sure about the intake. It makes sense but it might just help power at higher rpm's. Anyone else think porting the intake will help mpg to some degree?

As for the power pulley, that is also a great idea. Are they worth it? I mean would there be a measureable gain in mpg. Also what are the dangers of using a power pulley? I know they reduce the output of the water pump, but will it reduce the life of any components? What are the chances of the car overheating?

Has anyone used rodney's power pulley with a stock alternator? If I got one, it would definately be from him as everything I have received from him have been of beast quality....


I like creativity!
Any other great ideas?

quote Originally posted by tjm4fun: Hands Patrick the one aforementioned hell. (well, some had to, and he did ask politely)

Thanks, much appreciated.

quote Originally posted by tjm4fun: I've timed hundreds of motors by ear. after you learn how to do it, it is fine. not that everyone can or should do it, but nothing wrong with it with stock motors.

Well, I gotta ask then... In your opinion, was the gas mileage better on these cars after you had timed them in this manner?

I haven't put the power pulley on yet but do a search. Most folks didn't see a huge increase in economy, but there was some. The biggest advantage is to the charging system. The belt wrap around the alternator is much better so the charging system stays topped off much better. The slightly slower rotation of the water pump isn't enough to overheat the motor.

On the intake, search for that too. The upper isn't too bad and neither is the upper portion of the middle intake but the lower portion of the lower intake is way off but thats just the way they came from the factory. Some people have gone so far as to cut the upper intake in half horizontally and added more material to make it taller so that more air could flow.

Yes, port the exhaust manifolds. I should have clarified better. The exhaust manifolds are just gross.

Some of the newer Honda Fits have VTEC, not to increase power, but to increase fuel efficiency at low RPM. They are normally 4 valve per cylinder engines, but at low RPM, one of the intake valves is rendered inoperable. This is to make some turbulence, to mix the air/fuel mixture better.

So for a 2.8 L built for purposes of fuel economy, I wouldn't port the heads or intake, because high-RPM flow is not a concern. I'd leave the heads and intake stock, to maximize the amount of turbulence.

The new Fit VTEC is not to be confused with the real DOHC VTEC found in the B-series engines, which allow the valves to follow one of two cam profiles.

[This message has been edited by pmbrunelle (edited 03-11-2009).]

quote Originally posted by Patrick: Well, I gotta ask then... In your opinion, was the gas mileage better on these cars after you had timed them in this manner?

almost always better. timing by ear tends to set it on the high side, and advanced timing is usually best for higher mpg, however it can cause problems with emissions testing, especially on a borderline motor.

quote Originally posted by Patrick: Is that good or bad?

good

quote Originally posted by tjm4fun: almost always better. timing by ear tends to set it on the high side, and advanced timing is usually best for higher mpg, however it can cause problems with emissions testing, especially on a borderline motor.

Ah, so the trick might be to set the timing "by ear" for year round driving, then bring out the timing light once a year for the smog test. Okay, got it. Thanks!

My 2 cents. Remember, this is worth what you paid for it.

There's no magic bullet out there. Efficiency is what you're looking for, and you will not likely get better efficiency than when the engine was new. Most of our engines are old and tired. Your best bet is to make it run as much like a new one as possible. Keep the 195 deg thermostat. Don't port the intake. I would port the exhaust manifolds because I think it would result in more even flow from cylinder to cylinder. Replace the O2 sensor if it's old. Repair any exhaust leaks upstream of the O2 sensor. Clean the intake system. Clean or replace the sensors. Keep your tires inflated, maybe even a little over inflated. I wouldn't bother with power pulleys. They're designed to reduce power drain on engines at high RPMs, which is not where you're going to be operating if you're after MPG. Keep your highway speed down. Sorry folks, but 55 mph really does save gas. I did an 8 hr highway trip in an 86 Mercury Sable once at 60-65 mph (following my dad in his motor home), and it got 36 mpg. Don't run the engine to clear the frost from the windshield. Park in a garage in the winter. The colder the engine, the worse the fuel mileage. Just about any engine built with computer controlled sequential FI will have the same efficiency, because of emission standards. They all run at about the same A/F ratio, and therefore, get about the same amount of energy from a gallon of gas.

One area I would like to explore but haven't is ignition timing. Have you ever timed your Fiero? The timing jumps around a lot. At least mine does. I'd like to replace my timing chain & gears, and shim the distributor shaft to minimize the up/down play. I'm hoping that this would reduce the variation of the timing, and allow me to use more timing advance before pinging occurred. More timing advance = more mpg. If anyone's done this, I'd love to know how it worked.

As for hypermiling, some of the techniques are valid, some are dangerous. Jackrabbit starts aren't necessarily bad if it doesn't result in excessive braking. Hard acceleration to get up to speed on the interstate isn't wasteful. Hard acceleration to get to the next redlight a half a mile away results in bleeding off more speed with your brakes, and it IS wasteful. Try to minimize your use of brakes, but don't compromise safety. If you approach a light that's red (and you're not going to hold up traffic), push in the clutch and coast up to the light, and hopefully it will change before you have to come to a complete stop. But keep in mind that if you're in congested traffic, doing this might cause someone behind you to get caught by a light they shouldn't have, which of course, wastes fuel for them.

Most of this is old stuff for those of us who lived through the "gas crisis" of the 70's.

I think the number one influence on fuel efficiency is the driver. Fuel economy can fluctuate significantly, just from a change in the driver's mood (proven by Mythbusters!). That's why I always get in my "driving mood" when I get in the driver's seat (i.e. calm, rational, and alert). There are plenty of driving techniques for improving fuel economy. A quick Google search should reveal a lot of information on the subject.

Aside from that, anything that will reduce aerodynamic drag, rolling resistance, and parasitic power loss should improve fuel economy. Some examples:

-- Porting the intake and exhaust manifolds will reduce parasitic power loss, by making it easier for the engine to pump the gasses through the system.

-- A properly functioning ignition system will more efficiently burn the air/fuel mix than a weak ignition. A weak ignition system will leave more unused Oxygen in the exhaust, which will fool the ECM into thinking the engine is running lean. So it will dump in more gas, causing the engine to consume (but not necessarily burn, since the ignition system is weak) more fuel. It will also make the tailpipe emissions worse. Same goes for improperly gapped spark plugs.

-- A transmission with a "highway cruising" gear will reduce fuel consumption by reducing the RPM of the engine at cruising speed. It takes power to spin the engine. The slower you spin it, the less power is wasted.

-- A newer ECM with a "lean cruise" mode (for example, the 7730) will improve your highway fuel economy.

-- Tires with stiff sidewalls have less rolling resistance than mushy ones. Generally speaking, tires with higher speed ratings have stiffer sidewalls. For example, a tire with an "H" speed rating should have stiffer sidewalls than a tire with an "S" speed rating. If you're not interested in buying new tires, you can try increasing the air pressure in your tires. Just be careful not to exceed the maximum safe pressure of the tires, and be careful not to cause uneven tire wear. If the center of the tire tread wears out prematurely, the pressure is too high.

-- Reducing the overall weight of the car can improve fuel economy. The less weight the engine needs to push around, the less fuel is spent. This applies to the weight of the driver, too.

-- Make sure your wheel bearings and brake calipers are in good working order. A dragging bearing or caliper will reduce fuel economy. It's also a safety issue.

Any of the above, by itself, will not make a very big improvement in fuel economy. If you're serious about improving fuel economy, then you'll need to attack it from every angle. Several minor improvements will eventually add up to something noticeable. Just keep in mind that a driver who is in a bad mood, or is being a show-off, can throw all that out the window.

[This message has been edited by Blacktree (edited 03-11-2009).]

quote Originally posted by pmbrunelle: So for a 2.8 L built for purposes of fuel economy, I wouldn't port the heads or intake, because high-RPM flow is not a concern.

Wrong! If you want better fuel economy you DO want more useable RPMs. If you were to drive with a vacuum gauge - a great millage tool- you would notice that low RPMs -lugging- puts you between say 5" and 12" of vacuum and that's not good if you want to save gas. With our 60 deg V6s and the stock intake the more you go beyond 4k the richer the fuel mix!

Think about it this way, what takes more energy when you ride a 10 spd bike: Shifting way to soon or lettting your legs peddel faster and shifting later. You won't have to stand on the pedels if you shift a little later -same as reving your engine a lil higher. Most of our customers tell us they get better gas milage with our intakes; when they can keep thier foot out of it. Thus; anything you can do to get a better A/F ratio at higher rpm will help with the gas bills. Just look at today's engines, they don't run out of air at 4.5K !
BTW: I'm not talking about reving it to 6k either.

ca. smog allows 3 degrees before or after tdc to pass and when timing mine by ear at highest rpm motor warm or hot i was only 2 degrees off so you should b fine there

quote Originally posted by Francis T: Wrong! If you want better fuel economy you DO want more useable RPMs. If you were to drive with a vacuum gauge - a great millage tool- you would notice that low RPMs -lugging- puts you between say 5" and 12" of vacuum and that's not good if you want to save gas. With our 60 deg V6s and the stock intake the more you go beyond 4k the richer the fuel mix!

I disagree. More RPM's = more friction, in general. And also, as you pointed out, beyond 4k, the A/F ratio gets richer. I agree that lugging the engine too much is also bad. My 6 cyl seems happiest at about 2000 RPM.

quote Originally posted by Francis T:Think about it this way, what takes more energy when you ride a 10 spd bike: Shifting way to soon or lettting your legs peddel faster and shifting later. You won't have to stand on the pedels if you shift a little later -same as reving your engine a lil higher. Most of our customers tell us they get better gas milage with our intakes; when they can keep thier foot out of it. Thus; anything you can do to get a better A/F ratio at higher rpm will help with the gas bills.

I suspect that the better mileage from your intakes is due to more consistent air flow from cylinder to cylinder. The ecm doesn't know which cylinders are getting more air and which are getting less, so it supplies the same amount to each cylinder. So with your intake, the A/F ratio is probably more consistent across the cylinders.

quote Originally posted by Francis T:Just look at today's engines, they don't run out of air at 4.5K ! BTW: I'm not talking about reving it to 6k either.

The reason modern engines rev higher is to get more HP out of a smaller engine, and therefore allow the mfrs to claim better HP and better MPG out of their "new & improved" (but smaller) engine. Another reason they rev higher is that it results in lower torque, which results in lighter transmissions.

quote Originally posted by Formula Owner: The reason modern engines rev higher is to get more HP out of a smaller engine, and therefore allow the mfrs to claim better HP and better MPG out of their "new & improved" (but smaller) engine. Another reason they rev higher is that it results in lower torque, which results in lighter transmissions.

Low rpm often equates to higher bearing loads = more friction than higher rpm with lighter bearing loads. I had Nission pickup 4 cyl that I always reved much higher than others. Never lugged it, well when I gave it to my son-in-law it had near 400,000 miles on it with the orig bearings and crank! He put another 100K on it before he sold it. Revs are not bad, really high revs can be.

And it ot just todays engines that rev higher than our 60 deg v6s, you can g back to the 60s and look at cars from overseas, they all reved higher and got better gas milage as a result. Americans are still in the big V8 mindset - lots of foot pounds of tq no need for revs. Well those days are gone and they got crappy gas milage too. Most here in the states are must not comfy reveing over 3.5k.

We have spent a lot of dyno time -$$$- with these engines and can tell you for a fact, with the stock intake they get very progresively richer above 4K rpm, so much so, the wideband on the dyno could not even read it above 5+ k as the ratio starts drop to under 10 fast. Gas millage goes hand and hand with efficiency, thats why so many forgein engines in the past had higher compression ratios -10:1 etc- than engines made here, even thought it meant higher -more costly- octain fuel. If you want better gas millage, address all issues including those that limit rpm.

Interesting ideas about the intake...

What do you reccommend for synthetic oil? Mobil 1?

Also I have searched the forum and to me it seems as if the 3.4L OHV gets great gas mileage. Several people with the 3.4L are getting 32mpg + on the highway according to this thread https://www.fiero.nl/forum/Forum1/HTML/064631.html

Specifically Sardonyx, Three of Clubs, Moshman, and 1MohrFiero.

If you guys are reading this, what have you done to get those numbers? I mean if a 3.4L gets 35mpg I might just have to slap it on my Getrag.

Thanks again for all the replies...

I had a 3.4 pushrod in my 88 GT 5 spd. Cruising at 80 mph I averaged 34 mpg. At 65, I was getting 38 mpgs, I'll bet if I kept it at 55 it would do over 40 mpg. Drove from Memphis to Nashville averaging 80, and from Nashville to Memphis averaging 65. No stops, with the cruise set. I did the following:
Fiero Store's SS valves
Fiero Store's Performance valve springs and hardware
Heads ported and gasket matched
Darrell Morse ported throttle body and gasket matched intakes
Fiero Stores' Sprint Manifolds and crossover
High flow catalytic converter
Comp Cams 260h cam and lifters
Fidanza aluminum flywheel and spec stage 3 clutch
All internals balanced
Lowered 1" in the front with Rodney Dickman balljoints

Engine ran smooth off idle, idel surged a bit, but it great throttle response and would 155 mph wide open. Never felt the engine wanted to go faster while cruising and had a near perfect torque curve and the camshaft put the power band right where I wanted it. Never ever felt the engine lug or struggle. It was one of the best engines I've done, until it ate the camshaft on the new owner. I didn't use any additives the camshaft required to run. The new owner has since installed a 3800 s/c engine into the car.
I was disappointed with the overall hp though, for the amount of work and cash into it, I felt it should have been a bit higher, but the mpg's balanced it out. I've ridden in a modified 2.8- punched out to 3.2 that would eat the 3.4 for breakfast in a straight line. Guess I should have used 3.4 tdc pistons and shaved the heads a bit and run premium gas
My current Fiero has a 3500 LX9 and before I really started to tear into it, would average 33 mpgs. More if I could have kept my foot out of it, that engine always felt it wanted to go faster, so gas mileage suffered a bit. Then I went and did something stupid, put a couple turbos on it. Been having trouble with it ever since.
My next one will get a slightly modified Nissan VQ35 from a 350z. Engine is already torn apart and Comp Cams is working up a set of custom cut cams for me...

[This message has been edited by topher_time (edited 03-13-2009).]

I was hoping some one would mention the vacuum gage thanks ! this is the best addition for highway MPG improvement ,,,helps feather the throttle better ..People have forgotten the vacuum gage,, a neato jet addition to your gage assortment ,, you will be able to run the same speeds at a lower RPM ,, you get better efficientcy with a vacuum gage ,,better diagnostics,,its like having an overdrive !!

porting the fiero intake will not give the gains that porting the exhaust disaster will ,, but port match and intake manifold porting will increase efficiency.. this should help MPG .
If you are a Fiero fan you want your fiero to deliver the bestest, by gollee ,gee wizz MPG you can get in case gas goes to $10.00 a gallon..which is OK ,, but someday gas will be in short supply and we know not when or if that day will come..
The stock 3.1 would be the best for gas milage ..

[This message has been edited by uhlanstan (edited 03-13-2009).]

quote Originally posted by topher_time: I had a 3.4 pushrod in my 88 GT 5 spd. Cruising at 80 mph I averaged 34 mpg. At 65, I was getting 38 mpgs, I'll bet if I kept it at 55 it would do over 40 mpg. Drove from Memphis to Nashville averaging 80, and from Nashville to Memphis averaging 65. No stops, with the cruise set.

I just find it amazing that a 3.4L can get mileage that like. I don't think my 2.8 has gotten over 30mpg on the highway.

The modifications that topher made would help MPG and it is possible to achieve this MPG under good conditions,, Topher I beleave is a professional mechanic and probably had an better than average engine ..
It is very possible to achieve 36 mpg on a 2.8V6 5 speed at 65 ,70 with out spending a fortune ..a stock 5 speed will give 28 to 34mpg ,, you achieve 34mpg hiway on a V6 by "feathering" the throttle you use the least pedal to achieve highest speed !!
just porting the exhaust manifold removes a BLOCK on horsepower and MPG..a free flowing exhaust system on the V6 should yield 2 to 4 mpg on the open road
Top quality ignition wires will not increase horsepower but sometimes help MPG
index the spark plugs the best you can with out using index washers(I don,t like them),,more difficult on the front, use a mechanic mirror

Remember for a street car especially a daily driver efficientcy/efficiency is the goal, do things that increse performance that do not stress the engine before you add cams, hi comp pistons,ect
If you add 20 stress free horse power and lighten 100 pounds or more ,, the 3.4 is only going to out perform you in a pedal to the metal confrontation and 0 to 30 will be about the same
I recently added a hi performance clutch a mistake because it seem to weigh 2 pounds more than the clutch I removed ..defeating my wheel/axle weight removal procedures.
if your car has below average MPG always check for dragging brakes /wheels
around town the biggest waster of gas is rapid starts and poor planing as you approach traffic or stop signs/lights..
the next gas waster is following to close ,this may cause you to be on / off the gas
the V6 can not match the duke 4 cyl around town ,but on the hyway you can come close

[This message has been edited by uhlanstan (edited 03-14-2009).]

As reported Here, I'm now getting 21.36 mpg with mixed city/highway driving. Still not great, but better than it was.

[This message has been edited by Patrick (edited 05-28-2009).]