Hey, ive got a '88 GTA and im trying to figure out how to get better gas milage. Do i need to get new intake, exhaust or what should i do? Thank you, -Austin

 

if it's stock, then headers and a catback will help, also, look into a k&n filter and do a complete tuneup (coil, cap, rotor, plugs, wires, the whole 9 yards). also make sure that it's full of air in the tires and the fluid levels are good. other than that, it's up to you to change your driving habits!

oh, you may want to check in the exhaust forum and the tpi forum for better suggestions as this forum is based on fabrication, ie: making things from scratch.

 

Ride a pedal bike, increase your milegae dramatically

 

Park it.


I'd replace the plugs, wiires, oil, filters, and ensure it is in tune. You'll save gas that way. High-perfromance mods will just increase the relative density of your foot on the skinny pedal.

 

ive got the same car when i first got it i got 230 miles to the tank then i put a cold air intake on it did plugs wires cap rotor..... and got pretty amout of milage out of it and some awesome highwaymilage. but lately somthings gone wrong after i got my intake replaced due to a leak im only getting about 160 miles to the tank and a few places i took it said thats how "these cars" are after that i dont go to any of those shops any more.

 

How old was your car when you first got it? And let me know what you did to fix that problem when you figure it out.

 

Make sure your state of tune is good. A number 1 thing that will effect the mileage you get. An MSD has shown improvement in most of the vehicles I've installed them in, and don't overlook synthetic fluids in the whole of the driveline. And of course less driving.

 

Tune-up the car and granny drive it. The best tank I got was 313 miles. I had a perfect running 5.0 automatic too. That was on granny driving w/ 2.73 gears, mostly highway.

Plain and simple, these cars are not meant for economy. Just keep your foot light and do the best you can.

 

313!!!wow!!! wish i could do that! around town i'll PUSH it to 200miles...i suppose i could probably get 300+ if it was JUST highway though...

 

Better than what? What is the current MPG, and in what type of driving?

 

i get 21-22 on average with my 91 305 T/A.i found about 2 miles per gallon changing the cat back from a cheap crush bent 2 1/4 sytem to a 3 inch mandrel sytem with a hooker aerochamber. i found about .75 miles per gallon in switching to 5w20 synthetic over 5w30. i would not use this thin oil if your engine is not in good shape, particularly the valve guides can leak and cause false O2 readings. get a good alignment done 0 degree camber is the best for gas mileage also run as close as you can to zero for the toe. some people don't like zero toe because the car may seem a little darty with minimal steering wheel input. caster should be as much as possible around 5 degrees. clean the throttle body and take a look in the plenum and see how dirty it is. you may want to pull the the intake apart and clean all the carbon out of everything. of course a total tune up with good parts. do everything , plugs wires, cap, rotor, fuel filter, pcv, air filter, and maybe an O2 sensor. you might want to make sure you have good fuel pressure and good compression before any of the above.

 

the driver will make the biggest difference when trying to get max mileage. Short of tune.

 

you cant go wrong with a k&n filter and a flowmaster 80 series muffler

 

Take as much weight out as possible and do the basic stuff like thurough tune ups and keep the tires inflated. There is milleage to be had in the highway spark mode but I've never flirted with it, might want to check the DIY prom board; that or General Engine Tech would be a much better place for this type of discussion.

 

I wouldnt run a 0 toe unless your tie rod are made of unobtanium. Metal stretches and when you are driving at 55 mph, your toe actually goes to a toe out. cauising this \ / with the tires. Follow the manufactures specs on toe atleast. The camber is also set how it is to compensate for driver weight and turning, thus that should become closer to zero when you get in. Caster is for steering wheel return and to compensate for road crown. It is a non wearing angle which means it doesnt effect friction which doesnt effect milage.

make sure your emmisions is up to snuff too, not for environmental sake though. Cleaner burning = more burnt = more power per molecule of gasoline.

If you live in a non emmisions testing state (like me) pull your cat in favour of a straight pipe if your conscious doesnt bug you too bad. Or if you do, put a high flow one in.

Remeber this first. How much are you going to save by this part and what else does it benefit. A few dollar air filter will save more money in gas than you paid. A 400$ high flow cat, most likely wont unless your cat is really messed up.

Back to the fab board, fab up a "Tornado" if you want better gas placebo effect.

Drive nice, If i did, i got 15 mpg on a very worn out 350 with a crazy rich carb, If i was mean, 8 mpg. Double if i didnt break floor boards. yes this is a worst case scenario with many fubared parts into that car :-)

An exaust is sweet for mpg if you keep you foot up. Higher flow = less resistance = better efficency. Also, higher flow = more potential for flow = faster to spin high rpms = more gas used.

Not to mention the exhaust will get you looks to boot.

Keep windows up and t-tops on if it isn't too hot. Better aerodynamics, our cars forte.

Make sure your pressure is proper if not 1-2 psi high. Fill with nitrogen if possible, usually $10 for all four tires total, for life of tires. (At least at my tires plus)

Drafting off of semis seems like a good idea but a tire iron is scary in the hands of a angry truck driver.

Worse to worse, if someone tows your car you get great gas milage.

Fuel system flush is probably a good idea too.

 

Now why would you fill the tires with nitrogen?

 

Doesn't Nitrogen expand less as it gets hot, making a more consistent tire pressure across all operating tempretures?

Versus atmosphere, which is comprised of 70ish% nitrogen and the rest other gasses. An inconsistent mix to any degree will affect each tire pressure differently=BAD

Worth the money?? To me, with the cute little girl in my avatar, no.

 

Put in a T56 6 speed trans. I went from 16mpg highway to 25mpg.

Of coarse, around town the milage is about the same.

 

Yea you would never get the money back even if it was ten dollars back out of it. Now race cars on the other hand are a different story, it would be worth it there. Air planes and such use nitrogen in their tires but thats because when you are airing a tire to 250-300 psi its a helluva lot easier to carry a 1500 psi jug of nitrogen around than a powerful aircompressor and dryer, but a street car would never recover the money even if it was 10 dollars....

 

I thought the Earth's atmosphere was 77% nitrogen, too. So by using comperssed air, you're already getting mostly nitrogen.

Slick is right - If you already have a dry gas bottle for recharging gear and control surface accumulators on your truck, you might as well tweak up the tires while you're there.

 

a little off subject but I thought the atmosphere was something like 77% hydrogen and thats why they were pushing hydrogen powered stuff so much, am I off there?

 

Nitrogen is used in Aircraft for a couple of reasons, one there is no possability of ozone, which degrades rubber ( think weather checking from the inside) and two, it is inert and does not feed fires (common on aircraft brakes and scary as h***) think of a split rim with several hundred PSI with a flaming drippy rubber tire filled with combustible air.... unpleasant to say the least. oh and last the nitrogen used is "dry" nitrogen and will not introduce water (bad for balance and degrades rubber) into the tire.

If I read the post correctly he was refering to increased tire life by using dry nitrogen, mine never seem to last long enough to make a differance.

Dan

 

Exactly. I got 26.9 mpg on the highway with a mountain range between destinations, relatively heavy traffic (speed up, slow down type stuff, going from 6th to 5th a good bit), with a few PSI less in the tires than I'd have liked, extra weight of all my tools, and a not-yet perfect tune. Of course I was trying to get good mileage, but it can be done. I would like to see 30mpg on a steady road trip with good conditions.

This was with 3.42 gears and a freshly rebuilt stock L98 (except better internals and slightly lower compression-which hurts efficiency) and basically a cat-back and no cats.

I haven't tested city mileage because I've been busy wasting gas trying to tune it. However, with a T56 and 3.42's at least, going from 1st to 3rd to 5th with a light foot is possible around town as the TPI makes plenty enough torque down low for that. Otherwise, like others said, tune up, put lots of air in the tires, and drive really easy! Also coast to stop signs and lights from a distance (let off early). Weight reduction helps too.

 

Coasting, yeah, I do alot of that. Flip it out of drive and into neutral. One of the advantages of a manual tranny

Alot of good points here (where nitrogen in the tires came up I dunno). Anyways, a proper tune-up is the first step to increasing gas mileage i.e cap, rotor, plugs, wires, clean filters and valves (air, fuel & emissions). Properly inflated tires and weigh reduction certainly help in getting better gas mileage. Also, using a premium oil (synthetic) can certainly help in the long run, or at least changing your petroleum based oil at regular intervals (making sure aswell that all your gluids are topped off and clean including coolant & tranny).

I also make it habit to clean on a regular basis the intake and intake valves, injectors, combustion chamber and engine crankcase.

Driving habit also makes a huge difference. Driving hard you'll certainly feel it in the seat of your pants, and aslo in your wallet when it comes to pumpin' that gas

 

Heh… nice… that would make most of the rest O2… you wouldn’t want any sparks or anything even remotely warm getting near that mixture…

The reason that they’re pushing all the H powered stuff is that you can get it from disassociating water…

 

As far as getting some real MPG out of these cars it’s not _that_ hard.

For the most part they’re not enormously heavy, came from the factory with OD transmissions and have about the best aerodynamics of any production car (if I’m not mistaken the 3rd gen firebird still holds the record for a production car).

I was able to knock down some killer mileage in my ’83… suggestions:
- get it tuned right… you’ll find that there is some mileage to be found in messing with ignition, plug gaps (it goes up as the gap gets larger till the ignition can’t fire the plug consistently any more), timing, fuel delivery… on my crossfire car I found that the stock ignition was content firing with the plug gap as large as .055”. I also found that with the KS and running some extra timing I the mileage difference that I got between running 87 and 93 octane more then compensated for the extra cost. Since gas costs 3x as much now and the price difference between 87 and 93 is about the same as it was then but gas prices are literally 3x as much, I’d imagine that it would be easier to get to that point now.
- intake and exhaust is all about velocity… I’m sure that the longish/small runners of the crossfire intake setup helped this a lot, as did the relatively high compression (9.8:1 with iron heads, again, look at the gas comments above), and I saw a great improvement installing some headman headers with 1-5/8” primaries, and then I welded up some custom bent, mandrel bent pipes to 2 high flow cats, then to a flowmaster Y-pipe into the over the axle pipe and to a 3” outlet (no muffler, no extra bends or anything, the 305 sounded awesome this way also, 350’s sound awful like that).
- lower it and stiffen the suspension as far as you dare, it decreases frontal area and on our already low cars it really cuts down on the amount of air that gets under the car. My ’83 was lowered almost 3”, it made my formula with eibachs look like a 4x4 when they were parked next to each other.
- Ditch your big wheels, they’re HEAVY and increase rolling resistance. The 235/60/15’s on stock firebird rims are 20lbs lighter EACH then 245/50/16’s on stock “high tech” formula rims. My ’83 ran on 235/60 and 255/60 15’s, and the fronts were usually around 38-40psi and the back a few lbs lower then that in the back… it handled awesome on that combination, the bigger sidewalls made the super stiff suspension quite nice on the street, and there was much less rolling resistance then with lower profile tires. FWIW, swapping the stock 16’s off my formula to a set of 215/65 and some 275/60 drag radials mounted on some stock firebird rims not only lowers weight by 20-25lbs per tire, but I’ve noticed 2-3mpg increase on the highway even with a day of drag racing tucked in the middle of that.
- for you 700r4 guys: make sure your converter is actually locking up, adjust the TV cable as tight as you can get it and still not bind at OWT (you’ll find that if you let it self adjust you can manually get it one or 2 clicks tighter and it will not bind at WOT and will not readjust). Run a tranny fluid like B&M trickshift or type F, this and the TV cable adjustment will give you some very fast (hard) shifts that will help a little in around town driving (as well as at the track).
- keep the gears to something reasonable…, stockish/mildly modded 3rd gens tend to like something in the low 3’s. I don’t know that I ever saw one with 2.7x gears that really knocked down great mileage and that’s too little gear to have fun. My ’83 had 3.23’s with those 255/60 (27” tall) tires and was very happy with that combination. When I blew those up I stuck the 3.42’s in it from my WS6 and it was a bit too much gear for it, it felt like it wanted just a little less rpm all the time. Oh, and an open rear uses less gas then a posi or a spool… My ’83 had an open rear and I was still able to knock down high 1.8 60’s at the track on the radials, when I put a spool in my formula I actually lost almost a consistent 1-2mpg in that car.
- rear drums cause less drag then disks… drums don’t touch the shoes except when you apply the brakes, disks pads always contact the rotors. Make sure that your parking brake fully relieses

I’m sure there were dozens of other little tweaks to my Crossfire TA that I’m not thinking of, but all of it added up to a car that ran 13.8 in the 1/4, somewhere around 20mpg around town, and _get this_, a consistent 35-37mpg on the highway (at the time my wife, well gf at the time, lived in RI and I was in the DC area so I would drive up there every or every other weekend so I got a lot of time to experiment with what worked and what didn’t, unless I hit bad traffic around NYC/CT I usually pulled the trip off on one tank of gas…)

Now things that I never did try that are supposed to help:
- keep it running warm… warm is supposed to be more efficient (I always ran a 160* stat in the ’83, and not only that but I would drill a couple of bleed holes in it so it would run cooler).
- Warm intake air and fuel… (I did see slightly better gas mileage with the ram air hood working on the ‘83, I’m assuming because normally it would stay closed and suck air in through the ducting, but I also had some dryer duct added to the inlet for the filter box so it was drawing air from behind the headlight which should have still been relatively cool). I am considering trying to build a fuel heater for my truck to experiment with this, but I don’t believe warm air will help as much as it will hurt by forcing you to run less timing to prevent detonation.
- Ignition box… I always ran well tuned OEM ignition parts on the ’83 and it was quite happy. I did try this on my truck (’93 K1500 with an LO5, so it’s not that dissimilar to some of your LO3’s), and it does consistently see almost 2 mpg with the accel box on it, but there appears to be something very different with that ignition. Even with brand new plugs and the aftermarket ignition that one won’t tolerate more then a .032-.034” gap (spec is .035”) and run well when the EGR comes on and with either the stock or aftermarket ignition this thing chews up spark plugs which the crossfire TA never did.
- Electric fan… the ’83 always had a clutch fan on it, and I never tried a back to back comparison on the same car. I have a hard time believing it. The basic premise is that an electric fan only runs when you need it so it saves energy, the problem I have with it is that a clutch fan basically freewheels till it gets warm enough to need it and then the clutch engages (so it should only really run when it’s needed), and that point you have something mechanical directly driven by the engine which is a much more efficient means then converting the mechanical energy to electricity (one loss) and then converting it back into mechanical energy at the fan motor (second loss). The only place that I suspect that you might actually gain is that even “freewheeling” a mechanical fan does move some air and therefore use some power, so I do intend to try this on my truck and see what happens. I’ll pull the big clutch fan off of it and I have a big electric fan off of a Lincoln MkVIII and a duralle adjustable temperature controller…
----------
Oh, BTW, I think that in the late ‘80’s or early ‘90’s the RS’s and firebirds were actually sold as economy cars (I even remember seeing an ad actually specifying that with a camaro), they were available with smaller engines, OD transmissions, base 14” tires (15’s later on) and were classified as compact cars, I think they had highway mpg ratings in the high 20’s/low 30’s…

 

While you probably wont make $10 back in gas milage, you will in better tire life, especially if your tires are used at high speeds, or sit for long periods of time. Regular air is some 77% nitrogen, but, its the water vapor and actual water in the air. As the tire speeds up friction goes up. As friction goes up so does temperature. When temp goes up air expands, causing the middle to wear more. The water that is in the form of a liquid, but small enough amounts, to be un noticed when filling a tire up, gets hot, it boils. (Boiling is the phase from liquid to gas) When this liquid turns into gas, its growth factor is enournmous. This expedites the middle of the tire to wear more from over inflation. Nitrogen has no water in it, hence the name "Dry Nitrogen". Also, if you dont drive the car much, nitrogen helps keep the tire from rotting. Regualr air has many contaminants in it, nitorgen has well, nitrogen. This is also much easier on the rubber. So, it is a win win situation. There is a benefit of it and the $10 is for the entire life of the tires. So, $10 for 50,000 miles? If your trying to save gas money, that is definetly a reasonable tread life. I dont know about you guys but, $10 doesnt seem so bad for 5 or 6 years of driving.

 

I thought the trans am wheels I had were the lightest available as far as stock wheels go at 16 lbs apiece? As far as the nitrogen goes, I have been through alot of tires and have never had a problem with them wearing through the middle before the edges. They all have wore evenly edge to edge and of course I make sure they are inflated properly and the car is properly aligned. And my drive is a long transit at 75-80 mph. That is on other things besides my gta of course lol, tires dont last very long on there.

 

Did you actually weigh them?

The mesh 16x8 tend to run right around 19-20# and there is no such thing as a light 16” tire that I’ve found, I bet most combination is right around 50lbs. My high tech rims are 56# on one axle and 58# on the other (fronts have a thicker mounting pad making them heavier) with some gatorbacks on them (the original tires the car came with).

WRT the factory rims, the lightest 3rd gen rims that I’ve found are the 15x7 firebird rims, followed by the 15x7 early (>85) TA “turbofin” rims. None of the camaro rims come even close. Surprisingly, the lightest factory rims that I’ve found around are actually the 2nd gen honeycomb rims that the 15x8’s run 16-18# each, which is getting into the weight of some race wheels in a wheel that’s as durable as most OEM rims.

The lightest 17x9’s I’ve found are the 96-97 WS rims, I don’t have an actual unmounted weight but they tend to run 42-44lbs with 275/40’s on them which is about 10-12lbs lighter then all the similar sized vette rims…

Then add that that I doubt that you’ll find any 16 or 17” tire that will have the low rolling resistance of a lot of 15’s…

 

Why would a 15 inch rim have less rolling resistance than a 16 or 17....I weighted my crosslace rims and they weighed from 17.2 to 18

 

Cause 15 inch rims are just that 15 not 16 the 15 has less rotational resistance think of it in terms of a figure skater if she has her arms out while spinning she spins slowly but if she pulls the arms in she spins faster.

Lmao I tryed to explain it though I am not sure what diff it would make on gas mileage though I know it would help acceleration
try and put some 20 inch rims vs. 15inch and if it were possible the rims would weigh the same but... the 15 still would have less rotational mass the 15 inch having more of its weight toward the center of the hub where the 20 inch would be farther out same thing goes for all the driveline less rotational resistance the better gas mileage and acceleration

 

I'm not sure the "smaller diameter wheel" argument holds water. If that were true, we would not see a nearly 30 MPG Corvette running 19" wheels from the factory. Most cars now use 16" wheels as a minimum, 17" is so common it's like the 14" was in the '70s, and some fairly high-mileage cars are using 20s.

Rotational mass is less of an issue at cruise, although it's still an issue. Some large diameter tires can actually be fairly lightweight, especially coupled to a lightweight, large diameter wheel. It' s the mass/inertia imparted at the moment center of the wheel that counts. Whatever means are used to control that are up to the user/designer.

 

The current corvette and for that matter a lot of cars now are getting gas mileage almost in the range of what similar cars were getting in the early 80’s or so (and before you say it, HP comparisons are largely inappropriate since in most of these modern cars you’re not making any real hp when you’re knocking down MPG… I’ll put an old underpowered V8 up against a modern one getting the same mileage in a drag race any day if you keep things in the same mode as they are when they’re getting their nice mpg numbers, like when DOD has them running on 4 cylinders...), the only place that you’re seeing big improvements is with trucks, and even hybrid’s and assorted econoboxes are doing worse then similar vehicles were back then.

The fact is that most current cars that are getting OK MPG now have had the technology slathered on them thick to eek out gas mileage while still getting good performance despite design and styling choices that fight mpg every step of the way.

Vader, what you’re talking about in your second paragraph is the “radius of gyration” (the effective radius that the mass of the rotating assembly acts like), and with the exception of a few super exotic large diameter rims that you won’t find on most cars I doubt that you’ll find any wheel/tire combination that will come even close in weight or that radius to the smaller, more traditional ones. You can easily get largish OEM 15” wheels with big tires in the 3x lb range where it’s really tough to get 17” and larger wheels with similar width tires under 50 lbs, and at the same time those bigger diameter rims move that radius outward by moving the heavy parts of the wheel/tire assembly outward. Hell, forget the wheels, just compare the tires… compare something like a 275/50/15 to a 275/40/17, you’ll be surprised how much more the 17 weighs.

LoneCalvin, most of what you’re describing is mostly because of the difference in rotational inertia, but there is also some effect from wider tread and compounds/carcasses designed to give some to give you something resembling a ride with no sidewall, kind of like the same deal as putting a wider set of slicks on a car that already had enough traction, the new assembly weighs more and ‘gives’ more absorbing more energy and will actually run slower…

 

The best mod for saving fuel is a cherry picker with a 4 cyl engine on it.
My biggest pep-peeve is people who hot rod cars and expect good gas mileage. The reason we modify cars is to make them fast and make them our own. The basic fundamentals on good fuel economy is making modifications to the engine so it wont work so hard. such as intake and headers. If it breathes easier it wont tire as quickly

 

You know, theres nothing wrong in trying to squeeze in a bit of extra gas efficiency while making em go fast.

 

Yea there genius, ANYONE can rip off fuel injection such as tpi and slap on a carb to make it easier to tune it for you larger cam, exhaust, etc....but it takes someone with a little willpower and intelligence to make it faster but just as efficient. I bet a ls1/t56 equipped car would walk all over your car and still get mpgs that you could only dream of. Maybe you should learn more than the basic fundamentals and you would understand our questions better.

 

More power comes from better burning of the gasoline (figurativley speaking) you must be more efficent to get more power. A high flow exhaust gives you more hp AND better gas milage. So what wrong with sticking on a better flowing exhaust for power and gas milage? I drive my car nice duringthe week, better mpg, on the weekends F*ck mpg, i want power. Im trying for better mpg and hp. How about the street avenger carb, quick tune for mpg or hp. HP on demand and fuel economy on demand. Best of both worlds. Pet peeve on people getting more efficiency is how I see it.

 

The two concepts are not mutually exclusive. Higher efficiency is just that - Getting the most power from the least fuel. Operating at high efficiency while cruising is going to yield better fuel mileage. Operating at higher efficiency at WOT is going to yield more power. That's exactly what modern EFI systmes are bets at. Our systems are not all that modern, but certainly can be tweaked and modified.

 

You are such an idiot I almost didn't waste my time but here it goes...
For the price you pay for a LS1 T56 I could build a motor that would udderly distroy a stock t56 ls1's time. My friend has a 02 firehawk that gets horrible mileage indeed right now he is a bit faster my car is only a fraction of the price he paid for a ls1 t56. My car isn't a daily driver. I bet you are the kinda guy who buys the electric superchargers and the tornado blades to get better gas mileage? I have a complete TPI setup I will sell it to you... It was my choice to run a carb, not because I couldnt tune FI infact FI is easier in my opinion. Maybe you should learn the basic fundamentals of not looking like a retard.

 

I don't know if this has been mentioned or not yet, I think synthetic fluids in the driveline might help. Running smaller width tires would also help, like a 195/70/15 just for an example. They make intake gaskets with screens over the ports to help break up the fuel which might be worth a try, they are supposed to help with power as well as mileage, last I saw them was in the summit catalog. Ignition mods will pay for themselves in no time, a multi-spark box specifically, low resistance wires as well. A T56 might pay for itself eventually lol I went from about 15-18mpg to 20-22mpg. If you drove 10,000 miles a year and increased mileage by 5mpg it would be 300.00 savings @ 3.00/ a gallon. multiply that by a couple of years and you could justify (wife, parents, yourself) aftermarket fuel injection, six speed, or whatever.

 

If you could read, you would see that under my name says l98, hmmmm is that tpi? So why in the hell would I want yours. I hear that quite alot, "my friend" has such and such car, and he is getting terrible mileage is he? Maybe because it never gets out? I cant see any legit firehawk owner hanging out with the wits of you. Congrats on being able to build a engine that can kill a stock ls1, anyone with a summit or jegs mag can. Now if you reread what I said, if you are capable, I said while still getting ls1 mileage. Its not possible with a conventional sbc without some serious work but it is still a bone stock ls1 you are trying to beat. So you are only a bit slower than a stock ls1? point proven, and what mileage do you get again? If tuning fi is easier to you, why did you ditch tpi? I'd bet you cant tune a carb let alone efi. If you cant argue that facts, argue the person and it looks like you have good practice at that. You have your pet peeve and I have mine, TROLLS like YOU who are NARROW MINDED and cant find anything to do but go through and bash on other topics. Now lets see if you almost dont reply to this one to

 

this thread has obviously strayed. Lets try to help the guy instead of well so and so said this. I think he has a legit question. Vader and crossfire have been helping quite a bit id say. Playing devils advocate when needed. Synthetic fluids would make a difference. I would reccomend staying away from mechanic in a bottle, if you want a fuel system flush, have it professionally done. While I agree 100% with the t-56 swap etc. I think he is trying to do the best with what he has. I believe I read somewhere that the royal purple frees up horse power by less friction. less friction would also mean better efficiency/ mpg. I dont know if I can justify a $50 oil change but hey, I guess it lasts up to like 10K miles so at $20 an oil change every 3K, it saves you $10. Narrow tires are a good idea if you are thinking of replacing them. Less rolling resistance (See dragster w/ skinnies) Again, make sure your front end is tight and aligned. You dont want a bad tie rod giving you a bunch of toe out leading to more resistance and tire wear. A fuel system flush is a good idea. Definetly new plugs, wires, cap, rotor, (Have your module and coil checked at autozone etc) Mkes sure plugs are properly gapped. If you want to go with the t-56 route, stick some 2.73 gears in too. 1400 rpms at 80 sounds like good gas milage to me. Look into those programmers, alot of them have fuel ecconomy settings too. I know its long, just trying to help.

 

some of what has been said will help. everything working right & in good condition goes a long way toward better fuel mileage.
i think it was mentioned above, chip tuning will also help a lot.
after i got my 700 in my average in town was 14~16 depending on how i drove.
with tuning the chip i get 16~19 in town with no other changes & on the same spark plugs which now have around 70000+ miles on them plus i drive a few miles an hour faster now.

highway was around 20~21 running up to about 5 miles an hour above the speed limit before the chip tuning, now i get 25+ on the same drive at the same speed.
i know there is more left in the chip. i know a new set of plugs won't hurt me either.

 

Bet you dont even have to try to get good mileage with those 2.42 rear gears do ya, whats the lowest numerical gear made in the 3rd or 4th gen f bodies? 2.77's?

 

i think i would actually do better with a little lower gear, something around the 3.42 range.
my car isn't near as arrow dynamic as a thirdgen is, mine is more like a brick going down the road.
with the chip tuning im getting what my motor did when it was in a thirdgen which had a 3.42.

 

I the biggest difference i noticed is when I put a new cat on. Mine was all cracked and jack up and prob clogged.

 

According to
Pontiac Firebird - Formula - Trans Am CLUB - Engines
2.73 is the lowest stock.

 

You done looking stupid yet? Like I said before... for the price of an ls1 and t56 you could even buy a crate motor rated for far more hp as a stock ls1 you aint winning the argument you are just looking really dumb

 

While I agree that going all synthetic will definitely give you some better mpg, I’ve had extraordinarily bad luck with synth in my rear axles and only so/so luck with it in the trannies. I swear by it in my engine (either mobile1, RP or believe it or not walmart’s store brand synth in the daily drivers), at this point I’ll run cheap dino lube in my rear axles till I see good evidence that the axle lube formulations are getting better.

Too much of a good thing… t56 cars are pretty unhappy with less then about 4.10’s in the rear in 6th gear unless you’re going REALLY fast. In my ’97 WS6 I was happy with 4.10’s, where with the current 3.73’s I rarely use 6th gear, even on the highway you have to be going quite a bit over the speed limit on a flat road to not be lugging the engine in 6th. 4.10’s put you at about 1600rpm in 6th at 65mph, where you’d be at 1100 or so with 2.73’s.

As far as the idiotic carb vs fi argument… well:
- anyone can piece together something that will make more power then most crate engines if you’re not stuck with the constraints that the OEM is under
- assuming that you’re playing on an apples to apples field (similar parts tuned for a similar range with similar tuning) the FI setup will always be a few percent better then the carbed setup, mostly because there isn’t really a capability to adjust midrange like there is with FI. Yes, you can tune a carb to be fuel efficient, but it will not be the same one that will make best power and that tune will only be best in a very narrow range compared to an FI setup
- if you have a friend that is getting awful mileage with an LS1… there’s something wrong with the car. Yes, you can do better then the factory LS1 setup, but I really doubt that you have a carbed anything in a similar chassis that is getting better mpg and going faster.

 

Get this through your extremely thick skull if you can, I KNOW YOU CAN BUY A CRATE ENGINE FOR THE PRICE OF AN LS1, OR EVEN BUILD ONE OF IF YOU WANT, BUT TRY GETTING THE SAME MILEAGE AS A LS1 AND DRIVABILITY. GET OUT YA DAMN TROLL IF YOU ARENT GOING TO CONTRIBUTE POSITIVELY TO THE THREAD. YOU LOOK DUMB BECAUSE YOU LACK THE BASIC LANGUAGE SKILLS TO COMPREHEND WHAT YOU ARE READING. MAYBE YOU WILL UNDERSTAND BIGGER LETTERS.