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greasess 12-25-2014 05:13 PM

V8 fuel economy
 
I have a goal of building an engine for my 2001 camaro that will allow me to get 50 MPG. I know most people don't think of a V8 when talking about fuel economy but I think this goal is achievable. When the car was stock other than about 200 lbs worth of weight reduction I was getting 33 miles per gallon on the highway without any special techniques. If anyone is interested I'll post about how I plan on getting 50 MPG without aero mods.

Frank Lee 12-25-2014 06:00 PM

Let's hear it.

dirtydave 12-25-2014 06:22 PM

Full boattail and EOC P&G?

The_Jed 12-25-2014 10:31 PM

I'm intersted to hear your plans.

Cobb 12-25-2014 10:35 PM

High compression and high final drive? e85 with lean burn? :thumbup:

mcrews 12-25-2014 11:27 PM

It was rated at 26 mpg hwy so driving easy at 60 would get you close to 33. But not 50.

cRiPpLe_rOoStEr 12-26-2014 12:32 PM

At least this platform is lighter than the current Camaro, so it makes your goal easier. Regarding engine, I'd keep an eye for a Vortec 4800 or a 5300.

greasess 12-26-2014 08:13 PM

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greasess 12-26-2014 08:14 PM

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greasess 12-26-2014 08:15 PM

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greasess 12-26-2014 08:16 PM

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greasess 12-26-2014 08:30 PM

http://i57.tinypic.com/143deys.jpg
http://i59.tinypic.com/bfm39c.jpg
http://i60.tinypic.com/2wgx74l.jpg
I have a vortec 4800 in the car right now. I originally chose the 4.8 because of it's stout bottom end. The first picture is of a chamber that I had welded up on the plug side and shaped like a figure 8. The added quench area should improve the engine's detonation threshold allowing for more compression with a given octane fuel. This chamber should also push more of the burning mixture into a smaller area at TDC allowing for a faster burn that will require less timing and allow less heat energy to escape through the head. I have 2 sets of heads prepared like this. One of them can be seen in the second picture. The intake port walls were left rough after porting. My thinking is that this should improve fuel atomization because of the added turbulence. The third picture is of the "somender singh groove". After the engine is together without the groove I'll get a baseline and then take the heads back off, put the grooves in the chambers, resemble, retune and test again. The groove is supposed to increase mixture motion/turbulence. I'm also going to make a set of headers with anti reversion cones to improve scavenging and decrease pumping losses. I plan to do all this with 93 octane fuel at first and eventually move to e85 when it's time to turn the boost up. The engine has 9.5 to 1 compression now with what I think is a 58 cc chamber. I haven't done a cc check on the finished chambers yet but I hope I can get close to 11 to 1. All this turbulence and chamber motion along with a faster burn and less optimal timing should allow me to use significantly less fuel and actually make more power. The car has a 6 speed manual with a .5 6th gear, 3.50/1 rear gear ratio and 315 35 r17 tires and that puts me at 2,000 rpms at 90 mph.

Frank Lee 12-26-2014 08:38 PM

"More power to you"!

I was looking through the EM Garage for vehicles above 40 and 50 mpg... many three cylinder 1.0 m/t gas cars, hybrids, and diesels fail to crack 50 mpg. You have your work cut out for you.

greasess 12-26-2014 08:42 PM

I know that aero mods like a boat tail and things like eoc would really help me achieve 50 mpg but I want to do it without any of that. I would really like to hear what cripple rooster thinks of this. While doing research on google about ethanol and cr limits I always come across your posts.

greasess 12-26-2014 08:53 PM

I think I do have my work cut out for me but I also don't think the smallest engine is always the most fuel efficient. At 65 mph my engine is only turning about 1400 rpms. How fast does a 1.0 liter have to rev with factory gearing at 65 mph? Did you know that double the rpm quadruples the amount of rotational friction an engine experiences? I forgot to mention that I'll also be using reverse flow cooling and a propylene glycol based coolant that will allow me to run coolant temps at 240 F further increasing atomization and reducing chamber hotspots.

Frank Lee 12-26-2014 09:40 PM

4800 @ 3.3" stroke @ 1400 rpm = 770 ft/mn piston speed

1.0 @ 3.03"stroke @ 3000 rpm = 1515 ft/mn piston speed

Yup the 4800 would be turning quite slow- actually by some accounts too slow while the stock geared 1.0 is above it's best range of 1000-1200 ft/mn at 65 mph.

You aren't going to get 50 mpg at 65 mph either.

greasess 12-26-2014 09:44 PM

What speed do you think I may get my best mpg at and why?

Frank Lee 12-26-2014 09:48 PM

Search "optimal piston speed" for probably the best engine rpm range and for aero, the slower the better. Most American vehicles with automatic transmissions are said to get their optimal mpg at about 45 mph, a little above converter lock-up.

greasess 12-26-2014 09:52 PM

When I got 33 mpg I was on the highway between Pinellas County and Orlando going about 80 mph.

greasess 12-26-2014 09:56 PM

My car's DC is supposed to be .34 so it's average I guess. I wouldn't mind doing aero mods that aren't visible but I just can't have a boat tail on my car. I feel like that would be a crime.

greasess 12-26-2014 10:06 PM

I forgot to mention that I plan on making close to 800 rwhp using a gt45 turbo and run a high 9 second 1/4 with this car. This should take north of 20 psi of boost and I'll probably have to run e85 for that.

user removed 12-26-2014 10:07 PM

Most V8s use .5 gph idling. I told my neighbor my 2002 Insight CVT would go 40 MPH on the same amount of fuel his V8 chevy truck used idling (.5gph). To get to 50 MPG, your car would have to idle, without any increase in fuel burned while moving at 25 mph, with exactly the same amount of fuel it used idling.

My Insight used .11 gph idling, just over 20 % of a V8s consumption and the Insight was a very aerodynamic car with a cd of about .25.

Without some very serious aero modifications your goal is virtually impossible.

The work you have done on the combustion chamber is fantastic and a tribute to your capabilities, but by eliminating the aero factor your enegy consumption will not be reduced driving the car at any speed above 25-30mph.

That being said it still is possible that your modifications could help to improve mpg, but think of it like this, manufacturers spend billions on improving efficiency. You would have to achieve thermodynamic efficiencies approaching 55% which is the best ever achieved with very large diesel engines such as those that drive the largest container ships on the planet, running at less than 100 rpm, with a 3 foot bore diameter and a 9 foot stroke.

http://en.wikipedia.org/wiki/Brake_s...el_consumption

Can you get 50 mpg, within the limitations you have imposed (no aero improvements)? It's possible, but only if you use engine off P&G at average speeds of about 25-30mph.

regards
mech

greasess 12-26-2014 10:18 PM

Old Mecanic, You just made lots of good points. Two things that you may disagree with or may not have realized are that the car manufacturers could do much better and choose not too for financial reasons and most cars including your Insight have a pretty sloppy combustion processes that pass fuel through your engine without burning it. Your Insight along with almost every other vehicle on the road has a catalytic converter for burning that wasted fuel. I'm trying to use that fuel that would otherwise be wasted. I may not achieve my goal but if I do I want to make my findings available to everyone. Time will tell!

user removed 12-26-2014 10:43 PM

1 Attachment(s)
Compare the combustion chamber of the 83 era Nissan 280 ZX on the far right in the attached photo. The piston to head clearance was 1 millimeter on the flat portions of the cylinder head. The configuration you have produced looks very similar to the one in the attached photo. Nissan z cars in federal emissions configurations of the era had no catalytic converters. My 76 in factory emission trim had no cat, no air injection and no egr and it was emissions legal in 1976. I put an 83 head on my 76 on top of a factory new short block with flat top pistons. Compression readings went from 160 to 200.

That 76z would pull 28 mph highway andI could control the mixture with a rheostat that added resistance to the water temperature circuit. I was not really interested in maximizing mileage when I owned that car almost 20 years ago but it was a lot of fun to drive. With the original 3.45 diff (later a 3.90) and a .75 od 5th gear and weighing less than 2400 pounds, it was fun to drive, but could not hold a candle to a modern design with 40 years of fuel delivery evolution.

regards
mech

wmjinman 12-26-2014 10:55 PM

Hi greasess,
I really hate to be a naysayer, but I agree with Old Mechanic's opinion 2 posts ago. Getting it strictly with engine efficiency modifications, no aerodynamic work, and no extreme "hypermiling" driving would be a "trick" I would be VERY surprised to see you manage.

Now, with extreme aero (like boattails, fender skirts, grille blocks/air dams, etc) AND extreme hypermiling (driving below 45 mph, pulse & glide, etc) and getting rid of those 315 wide rear tires & replacing with skinny LRR tires and pumping them up to the max, I would be curious to see if you could hit 50 mpg then, because then I think you'd have a chance.

Frank Lee 12-26-2014 11:02 PM

Quote:

Originally Posted by greasess (Post 461401)
When I got 33 mpg I was on the highway between Pinellas County and Orlando going about 80 mph.

That car will NOT deliver 33 @ 80 consistently. Must have had a tailwind and/or fill error (variation in tank fill).

greasess 12-26-2014 11:31 PM

I know that having steam roller 315 rear and 275s in the front won't help fuel economy ANY but they are necessary for my other goals with the car. None of the mods I listed were originally intended to help with fuel economy. Economy is pretty far down on the list for me but efficient combustion helps both power and economy and that's what I have focused on. For the record I did get 33 mpg with a max speed of 80 mph. Some of the trip was at 45 mph on SR92. I would also like to say that none of the ideas I have discussed are mine. I'm combining what I feel to be the best ideas I can find. As far as the Z car not having cats, I'm not sure how many cars did in the 70s. I would like to thank all of you for the thought provoking interjections. Even if I fail to reach my goal I hope to learn from the experience. I welcome chriticism. I would love to hear from those of you that have actually modified your engine for better economy.

wmjinman 12-27-2014 12:10 AM

A few years ago, I modified a '73 Buick 455 in a Riviera for the "Silver State Challenge" road rally in eastern Nevada. It involved mildly ported aluminum heads with thinner head gaskets for a slight compression boost, a more aggressive cam, headers, re-worked Quadrajet carburetor, and Mallory electronic ignition. I also added a Gear Vendors overdrive, even though the Riviera has a 2.93 axle ratio already. I also put an air dam on it to cut drag and had the tires pumped up to 50 or 60 psi, as I recall.

The "run" was 90 miles one way, and my "target speed" was 105 mph, which I missed by about 2 seconds (slow) at the finish line. After the end of the "race", we had to go a few miles down the road and wait for them to open the road so we could return. There was a gas station a few miles further down the road they suggested we go and top off our tanks at, but I didn't go to it, just turned around and headed back. Now, about halfway back, I realized that might have been a mistake... I may not have enough gas to make it back!!! But I did, and then began calculating. From the gas station in Ely where I filled-up, it was about 30 or 35 miles to the start of the course. Then 90 miles down at 105 mph, then another 10 or 15 miles to the turn-around. Then that 10 o 15 plus 90 back to the start, where we drove the car onto the trailer for the ride home. I figured it had to be at least 240 miles, and I only had a 20 gallon fuel cell. So that's at least 12 mpg in a car that when stock and going 55 or 60 gets only 12-13 mpg.

The engine modifications were for the ability to run at speed, not for mpg, but we think it increased the efficiency some, or we would have surely run out of gas on that deal. I know the air dam and high pressure in the tires cut drag too, though. - and I had "salt discs" on the wheels too, which probably also helped the "aero" some...

The_Jed 12-27-2014 12:28 AM

Quote:

Originally Posted by greasess (Post 461403)
I forgot to mention that I plan on making close to 800 rwhp using a gt45 turbo and run a high 9 second 1/4 with this car. This should take north of 20 psi of boost and I'll probably have to run e85 for that.


This post makes me think you're not serious. I'm all for American V8 power and durability and I wish mine were more efficient, but I know 50 mpg and 800 rwhp can not be accomplished using the same engine with the same heads, cam, injectors, intake, tune, etc.

I read about a guy who had a duramax in an sn95 who would drive to the track at low boost and fuel getting 35 mpg, install slicks, crank up the fuel and boost then run 9's. Then he'd cut the fuel and boost and sip fuel on the drive home. That is plausible.

I'm planning to swap a few parts on my 302 that, along with some subtle aero mods, will hopefully enable me to hit 30 mpg.

But 50 mpg is outside the realm of possibility.

wmjinman 12-27-2014 01:26 AM

I agree with The Jed. It takes a certain amount of gas to move a certain amount of weight (and aerodynamic frontal area) down the road. A set-up that will move it really fast (like 9 second 1/4s), is gonna be burning even more gas just for having the capability.

Then you look at the cars that can get 50 mpg, and they're all smaller than Camaros. Then you look at the engines in cars that can get 50 mpg, and they're all smaller than the V8 in your Camaro. Doing a diesel, like The Jed was talking about, gets you a little closer to 50 mpg, but probably farther from the 9 second 1/4.

If you can succeed, you'll be an efficiency god, but I'm afraid for now I'll have to assume you're probably not an efficiency god.

Frank Lee 12-27-2014 02:54 AM

Quote:

When I got 33 mpg I was on the highway between Pinellas County and Orlando going about 80 mph.
Quote:

For the record I did get 33 mpg with a max speed of 80 mph. Some of the trip was at 45 mph on SR92.
I detect some irregularities here... Why am I reminded of George Wiseman (still on sabbatical)?

I've milled and port-matched the head on the 'Coupe but can't make any claims as to how much that helped fe, if at all. Blueprinting is nice but it doesn't do miracles especially at the low rpm end of the spectrum.

ksa8907 12-27-2014 11:03 AM

I wish you luck. You're going to have to address aero if you plan on 50mpg at a steady speed. I don't want you to be discouraged, but I think 35 is more realistic. To put it in perspective, my cts will do about 33-35mpg @ 55mph. 3.6 v6 turning about 1550rpm.

You should look up some of the work done by "pgfpro" on his first gen eagle talon.

pgfpro 12-27-2014 11:36 AM

Thought I would join this thread.;)

On my Talon, I also am trying to get great fuel mileage at 65 to 70 mph. I have hit a road block due to my stock gearing and aero (28.8 fps piston @ 70mph and a .29 Cd). I'll be lucky to get 40 mpg at 65 mph. My best so far is 38 mpg @ 65 mph and that was throwing everything at it including the kitchen sink.

My mods.

Engine:
2.0L
modified 1g turbo pistons, spray-guided crown.
modified head, spray-guided high heat direct port.
custom camshafts.
intake manifold, high heat direct port w/adjustable port angle injection.

Turbo System:
High-pressure Modified Blow-Down Turbine 13g internal gate dump to atm.
Low- pressure stock configuration FP Red BB, mid mount.
DNP Turbo exhaust manifold.
44mm Tial Bi-Pass waste gate.
FMIC 3" core.
LP Turbo pre-intercooler.
Tilton 40-527 external oil pump.
Jegs 12V Vacuum pump.

ECU:
ECM Link Engine Management system.

EGR:
HOT/COLD Electronic controlled cold EGR system.

Transmission:
Transtar/IPT 5 disk front clutch kit in stock basket, Transtar/IPT end clutches, double up stock flexplate, John Deere HyGard fluid, Foreign Muscle DSM (Transmission Control Unit), EPROM Upgrade full line pressure with pre-set rpm shift points.
2g lock-up converter.

Right now I'm working on getting the largest tire that will fit in my wheel wells. So far I have fitted a 1.5" larger tire then stock. The only way I will get close to my new goal 40mpg @ 65 mph is to reduce rpm. Piston speed is a killer when comes to fuel mileage.:(

Anyway I like that you are trying to have the best of both worlds (racing/fuel mileage) and hope for the best for you. Good Luck!!!

My Talon build thread.
http://ecomodder.com/forum/showthrea...awd-28776.html

user removed 12-27-2014 11:53 AM

I was going to refer him to your thread pgfpro. Thanks for bringing your experience.

regards
mech

Occasionally6 12-27-2014 06:37 PM

50 (US) mpg sounds very ambitious but there's no harm in trying.

It might be possible, subject to valve lift conflicts with that required for 800HP, to add in AFM from a later LS. The ability to switch to a 2.4l engine would reduce some of the pumping loss at low engine power requirement.

Likewise, it may be possible to use the variable cam timing from a later version of this engine.

Without having to respect emission requirements lean burn will help. You could also implement EGR. They won't be additive but could be complementary.

BMW had an engine series a few decades ago - ETA - that were optimised for fuel efficiency. Designed for low rpm operation with light valve spring pressures etc. Might find some ideas there.

A compression ratio optimised for E85 will help but there are diminishing returns. Once you get past about 10:1 the thermal efficiency gains really start to level out with further increase. Past 13:1 it's pretty flat. That you are using pressure charging will tend to push the CR in the wrong direction and probably less than 10:1. How effectively can you intercool it?

cRiPpLe_rOoStEr 12-27-2014 08:18 PM

You may even be able to get it to 800hp, but while doing an eco-drive you won't be able to use all that power. I guess you have already seen some motorcycles have different injection and ignition mappings that can be selected thru push-buttons, and you could try something similar in your Camaro. Either EFI Live or those aftermarket programmable ECMs such as FuelTech may give you the ability to get such control.


Quote:

Originally Posted by greasess (Post 461395)
I know that aero mods like a boat tail and things like eoc would really help me achieve 50 mpg but I want to do it without any of that. I would really like to hear what cripple rooster thinks of this.

The 4th-gen Camaro already looks kinda aerodynamic, and I like its design and would also rather not mess with it. In regard to EOC, I'm actually not unfavorable to it.

greasess 12-27-2014 10:29 PM

As for the valve lift requirements for 800hp, my stock cam is about .450 lift and my intake ports were tested to flow 272 CFM at that lift. That was without a valve job or flow form around the intake port. That should be plenty of flow to reach my goal. I know the DOD version of the 4.8 would help meet my goal but that won't work with my LS1B ECU. I would have to use an E67 or some other ecu. I use EFI Live and am familiar with tuning the LS1B only. I would also have to make up a custom harness to use a DOD compatible ecu. I can also command fuel in the "cruise" areas of the VE table to be as lean as I want while still running 11 to 1 AFR under boost so I can use the same map for the strip and eco driving. Also, I know that 11/1 CR isn't typically a good idea for boost but I have seen some people run 15 psi on a stock ls2 with 11/1, a 4 inch bore instead of my 3.77 bore, less quench area than I have, more chamber hotspots and so on. I haven't done it yet. I'm just saying that it's not impossible on 93. pgfpro, what cr are you running on your 4g63? Those are great results. If all else fails I'll ceramic coat my pistons, chambers and valve faces. That's supposed to get gains of up to 15% on economy for some engines. Thanks for all the reply. Keep the ideas and criticism coming.

cRiPpLe_rOoStEr 12-28-2014 03:36 AM

Quote:

Originally Posted by greasess (Post 461522)
If all else fails I'll ceramic coat my pistons, chambers and valve faces. That's supposed to get gains of up to 15% on economy for some engines.

I've recently been lurking about ceramic coating, but it's still not so widely available in my country.

greasess 12-28-2014 08:54 AM

This is the company I will go with if I do get any ceramic coating done. I saw a few of my customers make power gains with these coatings and nothing else done.

pgfpro 12-28-2014 11:49 AM

Quote:

pgfpro, what cr are you running on your 4g63?
The engine that's in the car now is at 8.0:1 This is a modified stock 1g piston on a deck block and milled head. I'm using this piston because I wanted to test running in lean burn around 30:1 A/F at medium load 0" Hg to 2psi at freeway speed.

For the racing part I use these stock cast 1g pistons becasue I'm trying to run a high 9 second pass on pump fuel. I did some testing last year and while pushing the envolpe I broke a few pistons when the engine detonated.
When these pistons break they just crack the ring land and drop down in compression, and so far I haven't hurt the bore and or head. I then can drive the car home and change out the piston without pulling the engine in less then 8 hours and be ready to race the next day. i have 8 pistons ready to install at all times.

I have also another 11.5:1 engine I will be testing later this Summer. This is my E85 engine with a built bottom end.


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