How to build a muscle car for better fuel economy?

[Phoenix'97]

Originally Posted by BLSTIC

First up: I refuse to read 20 pages of replies to see if what I am about to state has already been noted.

I don't blame you! I thought this thread was over until I checked my e-mails!

Originally Posted by BLSTIC

I'm unfamiliar with the numbers and brands you are working with, but it sounds like 'big runners' are, well, big. If they are large diameter, they will lose port energy at low rpm, and this will adversely affect cylinder filling, which adversely affects torque. Whether this is bad for fuel economy depends largely on your cam and whether you are going for a semi-atkinson cycle. More on that one later.

The TPI intake was designed for the 305 SBC engine and this is why anyone running this intake on the L98 SBC complains about the lack of airflow for high horsepower performance, the large tube runners only allow for a minor increase in airflow without sacrificing low end power production which kicks in at 2000 RPM. However, the overall performance is hardly noticeable by accounts of those who use these intakes with larger runners.

I don't drive my car around town with a high RPM performance mentality, I drive it around with low RPM performance in mind! This is why I have been researching how to increase the fuel efficiency of my LT1 while also increasing the engines performance at low to mid-range RPM which is why the TPI is PERFECT for my driving style! Since I also want to have fuel mileage comparable to a 6-cylinder engine or maybe to achieve 4-cylinder engine fuel economy, I am looking into hybrid technology as well and how best to apply it to my application. I want to drive around town and have the full functionality of my V8, but there are areas where hybrid technology can help minimize the fuel consumption from stop-and-go city driving. The age of my car's components is also an added factor as well.

Originally Posted by BLSTIC

Long tube headers for low-rpm are unfeasibly long. 60" 4-1 headers are good for a 2500-5500rpm band on a 302-HO. If you intend to try tune lower than that they might not fit. Don't forget that cat converters mess with tuning lengths. If you can (and the length is appropriate) you want to fit a pressure wave termination box immediately before the cat. It simulates open headers for correct collector length tuning but allows connection to the rest of your exhaust. Also, if you're concerned about emissions, make sure your exhaust stays hot til the cat. This might involve wrapping, but heat shields and/or a coating are probably enough.

I appreciate your comments and I will take the time to look all of these suggestions over. This project is a few years out but there is a TON I need to look into before I commit to overhauling my car into something brand new and definitely "With the times".

I have been given headaches over how I can use long-tube headers optimized for my power band and still retain the functioning of my catalytic converter and emissions hook-ups. I was planning on modifying my car with self-heating oxygen sensors to address this issue and help with cold-start and warming. I want to use catalytic converters because I am very conscious of emissions pollution, which is why I am determined to use GEVO Iso-Butanol in my car when the time comes! I am still going to need a catalytic converter to address NOx emissions even though Iso-Butanol burns so much more cleaner than straight gasoline.

[Phoenix'97]

Originally Posted by triangles

This may be blasphemous but you could get a 2.7L 4cyl Toyota engine from a Tundra or 4runner and simply swap the engine. You'd probably have to get a custom drive shaft made and then you could play with different gearing in the rear to optimize fuel economy. I'd be surprised if you couldn't beat 30mpg. Take a look around and see what other rear engine 4cy cars are out there you could potentially do a swap with. A miata might work, I would advise against a Chevette motor. Those cars are one reason I can't bring myself to buy a Chevy today. I'm not familiar with what Chevy has in the S10 or other smaller trucks. Maybe one of those motors might make sense for a swap.

I appreciate the thought, on top of suggestions for swapping in a diesel motor! However, the goal is to overhaul my V8 LT1 engine and improve it in terms of power production and fuel efficiency, which is a tough act to balance, not spend additional money to swap in something new.

Besides, I enjoy having a moment once in awhile to let loose and floor the gas pedal! Then, the beautiful idle from my LT1 and then hearing the growls and snarls from acceleration and engine braking are what really make the experience rewarding.

[Xist]

I try to use the search function before sharing something that may have already been posted.

[George Tyler]

Still sounds to me a turbo and cam change to give later closing of inlet valves will do what you want, small turbo, comes in below 2000 rpm but not much boost at 6000. you could get a huge increase in torque over a wide power band. Have you driven a vw golf 1.2 turbo? have a look at the specs...
I am currently working on a magnaflux machine at a aircraft engine company at the local local airport, there is a diesel aircraft engine there they have just worked on, it replaces a 350 cu in gas engine with it's 2L diesel similar power but better at high altitudes, 40% fuel savings, much lighter too. It is basically a mercedes van engine, but with an aliminium block, turbocharged as normal. I think it's actually VW in origin, as the mercedes and VW vans are made in the same factory with mainly shared components.

[Smitty]

Not to be a wet blanket, but
1) firebird with an LT1 is not exactly a musclecar, &
2) why are you trying to maximize a mediocre engine in a big car? seems awfully counter-intuitive.... get a honda or something.
That being said, taller gears, a 5-6 spd manual, & aeromods will get you the best results. Athough watch how much you spend on such an endeavor; thousands spent to modify a boat will take forever to get your expense back in gas savings.

[freebeard]

I've lost track of which Firebird. The mechanic at the local shop, Rich's German Motorwerks, drives a 4th gen F-body Camaro. It has the V-6 (stuffed back up under the cowl). It has better balance than a V-8, like a 4-cylinder vs VR-6 in a Golf.

Go for Buick eAssist or Dodge eTorque, plus taller gears and underbody aero. And Isotropic Superfinishing.

[BLSTIC]

Or you could tune the engine *exclusively* for low-rpm and run a relatively large turbo (or, you know, two).

A large turbo has a number of advantages in your application

1: Lower backpressure - Reduces pumping losses and likelihood of detonation. This means you can run higher compression than you otherwise thought and your engine makes more horsepower per psi. Also uses less fuel on the highway.
2: More efficient compressor for higher airflow - more power per psi thanks to less power draw from the turbine
3: Higher boost threshold - not *usually* a plus, but in your case you already have a disgustingly large amount of torque available at low rpm, it would be difficult to do high load efficient driving if you had 500ft-lb at 2000rpm
4: You get to run a smaller cam and high compression. Because the boost won't be there at low rpm, you can have high compression. Because the cam is so tiny at high-rpm, the boost is merely bringing things up to speed again and your compression ratio isn't too high for the actual amount of air in the cylinder.

On the one hand, your turbo V8 only makes 400-450hp. On the other hand, you have a turbo V8...

The really good news is you can do this *right now*. Rear mount turbos are a thing, and moving any turbo to the back of the car increases its effective turbine size, a chinese $150 T3/T4 with an internal gate would be ideal for an experiment. It also means that boost response is exhaust temperature dependent so you may end up with a car that you can't accidentally boost when it's cold. And has epic spool noise

[freebeard]

carthrottle.com:The Advantages And Disadvantages Of Rear-Mounted Turbos

...and moving any turbo to the back of the car increases its effective turbine size...

How does this work? It's blown through a long skinny exhaust pipe.

[BLSTIC]

Because of the lower temperatures back there, the volume and pressure of the gasses flowing through the turbo is lower by the time it gets back there, despite the mass being the same. The result of *that* is that the turbine extracts less energy from the exhaust, and the exhaust physically fits through the turbine and its housing easier. Both of which are also important symptoms of a larger turbine wheel and housing.

However, you don't get the added mechanical advantage of having a larger turbine wheel by just plonking it at the back. I'm certain that proper housing design could entirely compensate for this though should you wish to have that effect, by having a small area, large diameter housing. I wouldn't be surprised if that's what STS do.

So it's not *exactly* the same, but it's a rough emulation

[slowmover]

Originally Posted by Smitty

Not to be a wet blanket, but
1) firebird with an LT1 is not exactly a musclecar, &
2) why are you trying to maximize a mediocre engine in a big car? seems awfully counter-intuitive.... get a honda or something.
That being said, taller gears, a 5-6 spd manual, & aeromods will get you the best results. Athough watch how much you spend on such an endeavor; thousands spent to modify a boat will take forever to get your expense back in gas savings.

A car that carries but two people, nearly no luggage, and can’t tow a trailer of reasonable size isn’t one on which to waste money.

After cutting unnecessary cold starts (using combined trips), and establishing new habits in maintaining, repairing and driving the vehicle, there won’t be much left in the way of savings.

Count the gallons.

If this is only about better FE with the same **** habits, it’s a real waste of time.

A muscle car is a family car with greater acceleration. That’s it, if one understands the history. Stoplight to stoplight. From there it grows branches.

But if there’s anything less practical than a pony car, we’d like to see it.

“Practical” is ones family. A man with a “car” that leaves them out is good for nothing.

Build a sedan, at least.

Second time: How many gallons saved annually after revision of habits, first?

What will be the percentage change to the annual average fuel bill, second?

It won’t be 50%, will it? Won’t offer savings significant to justify (income then dedicated to useful purposes).

Don’t reply, do the numbers.

Better handling and braking from a family sedan is a HP increase, as more becomes useable. Etc. Look down this path. A 9c1 Caprice. Police-spec. One of those branches from above.

A post 2003 Crown Vic. (Can easily hit 30-mpg Highway). Mercury Marauder gear.

If it’s “all about me” then disregard entirely.

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