How to build a muscle car for better fuel economy?

[gumby79]

Ecky
This would be capable of being a compleet replacement for the gas powerplant (g54b) with a 5 lb-tq increase in over all torque in my little D-50. Nice find.

[Hersbird]

I had heard that the Ram redesign would easily make it the most fuel efficient full size pickup. "drag coefficient of 0.357 on the Quad Cab with rear wheel drive."
https://www.allpar.com/trucks/ram/2018-1500.html

[EfficiencyLover]

It may be useful for you to investigate using the Comp Cams Cam Quest program (free online) to learn about tweaking cam fitment for maximizing low and mid-range torque production. If you haven't already used this program, you'll see why it's being suggested. It can help with component selection. The GM TPI manifold is a gem for torque production. The second thought is using Total Seal zero gap rings. Give them a call and learn from people who can give experience-based advice on this area of efficiency - and longevity. The third thing is considering the use of Rhoads lifters on the intake side of your valvetrain. You will probably end up using a dual pattern cam, to compensate for the exhaust port's weaker flow (on Chevy small blocks' heads), so as a simple substitute for variable valve timing, you might find this useful. Just be aware of compression ratio/valve timing issues. Perhaps that is why you want to use the higher octane fuel. That may not be necessary - and you may not be so geographically limited by its availability - if you select your hardware combination carefully and keep a tight quench dimension. The people who race and develop engines are pursuing the same basic goal that you are - efficiency. They are usually not so concerned with longevity. :-) You can still use what helps you to achieve your goals and disregard the aspects that don't. This sounds like a worthwhile and fun project. Good luck with it.

[mhayes]

I am glad to see here that someone has the guts to really build an engine from the oil pan up in order to squeeze as much mileage out of it as possible. I like your general idea, and the Firebird is a great platform for a build such as this. Anyway, the ideas about the pistons and cylinder heads are intruiging, but I wonder why is it necessary to fork out $1k on a set of heads that will likely not gain you anything in economy. You can buy a lot of fuel for that much money. It seems that your funds would be better spent cleaning up the factory heads with a normal bowl blend and long radius clean up and then a valve job (30 degree) that will allow more flow at low valve lift. We want to reduce parasitic losses and restrictions to flow where it will do the most good. Consider having the block true decked to 9.00'' and having the piston stick out of the bore by .010'' in order to increase quench and detonation resistance. The LT1 already has a CR of 11:1 from the factory, and this will give you about a half a point increase. The reverse cooling is a nice feature, and you should have no trouble staying out of detonation provided that you select a cam that does not have too tight lobe separation, causing dynamic cylinder pressures to get too high. The engineers were not idiots, and I would not stray too far off the target of a 117 degree centerline. That is already a pretty wide separation.

As for the TPI on the LT1 heads, I do not see how that will benefit you in terms of port velocity or fuel distribution over the stock TPI that is already there. Again, this is likely to be wasted effort and money. You already have a port injected intake. The older TPI runners are longer, but I bet that there is comparable inertia in the newer design to fill the cylinders effectively at low speed.

As for suggestions to improve on your plan, think thermal management. Have your pistons, valves and combustion chambers thermal barrier coated to retain as much heat in the cylinder as possible. Have your headers coated as well. This will keep exhaust pressure wave velocity as high as possible due to the higher temperatures in the primaries. Consider a port mismatch on the bottom of the exhaust ports to create an anti reversion dam. This will minimize reverse flow back into the cylinder during overlap.

Also, always run the longest connecting rod you can. The reason for this lies in the geometry of the crankshaft. With the longer rod, the crankshaft will rotate more degrees before the piston starts to come down in the bore, therefore the crank sill be closer to 90 from TDC as the cylinder pressure rises to maximum. This allows for more mechanical advantage. Try to get a 6.2'' rod.

Also, you didn't mention transmission or axle ratio. A combination like this should be geared as high as possible. A T56 would be the best, offering a 50% overdrive. This is a cool project. I hope it turns out well.

[George Tyler]

Originally Posted by Phoenix'97

I will conduct more research but I will save this image for reference. If Toyota has found optimal A/F ratios for varying driving conditions and throttle positions, then it should be good enough to tune my LT1 for! Thank you all for your comments and helping to expand the possibilities with my motor!

Attachment 23321

Interesting, I have had 7 Priuses, the oxygen sensors are not wideband, so they don't have a way to run lean, and this on a car that is "all out" for good fuel consumption!
Thinking about this, from first principals, the highest efficiency happens with the highest possible temperature peak from a given amount of fuel. The improvement in consumption with lean burn comes from reduces manifold vacuum, so with the Atkinson cycle best fuel consumption may not be with lean burn!
I actually like Mazda's solution to Atkinson: their "Miller cycle" runs similar inlet timing to the prius in aktinson mode, but then a turbo to make up the lost charge in the late inlet cycle by running positive manifold pressure at high power output. no valve timing control needed, can do it on an old car with DOHC quite easily.

[Hersbird]

Often A/F ratios are limited by how emission systems work so I wouldn't say the Prius is optimized for economy without adding within emission rules. I personally feel the catalytic converter is a part that should be reconsidered a mandate, as well as certain types of emissions being all that terrible across the board. What does controlling NOX at such a high standard do to other pollution. One day we might find 100 years of catalytic converter use has created a superfund site on the side of every single interstate highway with heavy metal contamination. Meanwhile smog hasn't been a thing in 50 years and we burned a billion extra gallons a fuel to keep our converters hot.

[freebeard]

I dug up a post I did on 20140831 — Hot-rodding the Toyota MGR — Permalink #23

For the record:
Isotropic Superfinishing
Isotropic superfinishing - Google Search
In-house REM Superfinishing process by Weddle Industries | Weddle Industries | High Performance Driveline Components for Race Vehicles | Off-Road Transaxles, Clutches, Gears

Cryogenic Tempering/Hardening
en.wikipedia.org/wiki/Cryogenic_hardening‎
cryogenic tempering - Google Search
High Performance Brake Pads and Brake Rotors - Frozen Rotors

Another one, Heat Rejection Coatings
Why Coat Radiators, Intercoolers, Oil Coolers And Casings?

If interested you can go there for links.

[ECONORAM]

Originally Posted by spacemanspif

It's been shown on this forum that DFCO (deceleration fuel cut off) is less efficient than coasting in neutral so no real need to add DFCO; you're better off staring to coast in neutral earlier instead of relying on the engine to slow you down.

Could you show me where that is? I ask because I do not see that happening with my truck, as the PCM artificially raises the idle speed when the truck is moving and you shift into neutral. It really annoys me...

[ECONORAM]

Gee whiz, I am late to the party on this thread.
I want to suggest you look at different fuel injectors. Not bigger ones, but some that have many more (smaller) holes per injector. This will better atomize the fuel going into the cylinders...
I don't know if my ATI under drive helped fuel mileage a bunch, but it did free up 8-10 parasitic hp. And the engine runs a bit smoother.
[edit] forgot you could get some devices to adjust the air/fuel mixture to something like 15.5:1. That should give you another 1-2mpg. Zetronix makes wideband devices for that. http://www.zeitronix.com True, the return on investment (ROI) is rather lengthy, but there would be bragging rights. *Besides, ROI doesn't stop lots of people from blowing money on things that actually drain money faster from their pockets...

[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.