Quote:
Originally Posted by triangles
I'm also not reading thru the 20+ previous pages so I apologize if anything below has already been suggested.
I had recommended the engine swap as a cheaper easier alternative than monkeying too much with your thirsty V8. From what I know about late 90's engine technology, it's fuel injected and has a computer managing the ignition timing and fuel injection. This is probably both a blessing and a curse. I'm not sure what is available in the aftermarket that allows tweaking of the base engine map. I'm going to assume there isn't much (probably wrong) but the first thing I would do is get some cams that are optimized for fuel economy. Sure you'll take a hit in max HP but like you said you're not racing it. Further you could also see what pistons are available to change the compression ratio to work best with the new cams. Beyond that there' isn't much you can do and even monkeying with the cams and pistons probably won't get you more than 1-2mpgs since the factory ECU will try and compensate for the changes you make.
Taking things to the next step you can "delete" your cars ECU and put in something like a Megasquirt or microsquirt controller. This will give you complete control of the engine map (ignition timing and fuel) and you can really tune it for efficiency. I would guess this might yield +5mpg maybe as much as +10mpg if your factory engine is really inefficiently setup and you drive very efficiently. I'll repeat that is just a guess but it's about the only way I see of making the engine more efficient.
I am doing this with a 2 cyl motorcycle that is optimized for HP and is also carbureted. Since the ignition control is so crude and you can't lean out a carburetor for low load cruising conditions as well as you can with EFI I should see some significant improvements. That's kind of the beauty of having computer engine management. Tweak for max fuel economy at light load and then switch to max power when floored. It's kind of like cheating having the best of both.
I'm sure this one has probably already been thrown out there but you could find a way to "deactivate" 4 cylinders under cruising conditions.
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Quote:
Originally Posted by BLSTIC
It's a blessing because the stuff is technically there to get the best economy. It's a curse because you can only get incremental improvements over what's there (without altering factory goals). It's not like cars were ever programmed to use more fuel for no reason (once they got the programming ability, which I would say was a late 80's thing), so you've got to figure out *why* it's running too rich or too lean there. It's like: Why run 11:1 air-fuel ratios at high load? It costs power, uses fuel, and doesn't add to engine safety... Oh wait I have cats and they overheat after 30 seconds without the low egt made my running rich.
Sequential injection can only get so much when you're not running massive injectors, and injectors have only improved so much since, especially for two-valve heads (four valve heads now have injectors that have two-cones that point at each inlet valve and timing so that at low loads they can put the entire charge through an open valve)
Spark control in the aftermarket basically hasn't changed since the late 80's so you get screwed over with not being able to use the dual-knock sensor with 4-method closed-loop spark control factory cars got around 2005. There's one Australian car which has an increase in high load torque of about 7% by running premium fuel simply because its spark management and knock detection is so damn precise. No such luck for the aftermarket. Program your ignition, have a knock sensor if it pings, no real continuous octane detection and optimisation.
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Well, this is where things may get interesting. The second-generation LT1 has a horrible optispark distributor ignition system. I do intend to perform a coil-over-plug DIS conversion which utilizes LS1 coils and the LS1 ECM. I am not sure if this ECM will allow more tuning ability with a DIS ignition system but I need to research it.
BLSTIC commented that I should use the latest equivalent fuel injectors for my car since they are likely able to better handle tuning for leaner fuel mixtures and they are more accurate in their fuel delivery versus 1980's era fuel injection technology.
When looking for a camshaft, I am going to try to find a happy balance between performance and fuel economy. I was recommended on other forums to use modern camshaft lobes versus off-the-shelf camshafts, so I need a custom grind. I want low end torque that kicks in at 700 RPM and falls off around 4500 to 5000 RPM, which is exactly where the TPI intake manifold drops off with airflow.
EfficiencyLover mentioned Rhoads lifters on the intake side of my valvetrain for variable valve effect. This might be an interesting modification and I would have to see what the engine builder thinks of it since I won't be using a big cam, rather a very mild stockish style cam, maybe something that comes close to ZZ4 or Crane227 performance. For the TPI intake, I was suggested on another forum that my exhaust valves will need more lift on their end so 1.6 I believe for them and sticking to 1.5 for the intake side.
mhayes mentioned 6.2'' long push rods.
So, clearly I have a LOT to look over and research in order to determine what would be best for my set-up. If a smooth and complete underbody tray with rear diffusers is not too complicated and expensive to have done, the aerodynamic benefits along with wintertime driving protection from the salt is also an added bonus.
With regards to a plug-in hybrid kit, if I am unable to find something that turns my front wheels and permits electronic assisted all-wheel drive, I am not sure if an inline drive kit would be worth it.
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