Better MPG...Cam, turbo or SC?

[grayman]

Howdy Gang. This is my first post. Proud to be a member.

Question: Does anybody have a rough (or precise) idea of how a CAM (20-30 hp ??), a 6psi Turbo (if I can find a comprehensive kit) or something like the 6 psi RKsport SC compare in MPG?

This '01 v6 bird has 7000 miles on it. It is and will be my daily driver for many years to come. lovin it for two months now...Yeehaa!)

Have done all the 'free' and easy mods already...just getting an idea about a more major and substantial power modification. I have been reading, reading and reading and am starting off my quest with the above basic question.

(I figure I'll get a savings on 87 octane rather than premium fuel by going with a N/A cam over FI to start....)

TIA for your help and info. grayman. :cool:

[andrew.brandon]

turbo is usually better on gas since your not boosting much till you hit higher rpms but it can really depend on your setup. nitrous might be better if your worried about gas millage. but if your into some serious power under the hood you can pretty much count on not having good gas millage. just a thought

[andrew N.]

I had nitrous on my old 3.4 c'maro. It was nice having good gas milage AND be able to consitantly beat my two friend's 94 Z28 and 96 4.6 mustang GT.

[oil pan 4]

The most efficient way to make power is all moter.
On an all moter car it takes about .5 lb/hr of gas per hp with a turbo it takes about .6lb/hr of fuel per hp.
What does that mean? It takes about 10% more fuel to make the same peak hp with turbo as N/A.
Don't buy 87 it is a scam. At least do a gas milage test on reg Vs. premo it's the only way to know for sure. Mid grade isn't much better than reg.
Here is some thing I typed up on a nother board:
I gave up on the cheap stuff a long time ago.
The 87 gas is the crap, it's like an old left over sandwich with a bunch of stuff that you don't reconise in it.
Me and my engineer friend figured out that his old 1987 dodge daytona 2.2L (N/A) cost 1 cent less to go a mile with premo gas (shell most of the time) insted of cheap stuff (87 octaine).
My moms ford explore detonated like crazy on cheap stuff when on the interstate. It's interstate gas mile all most dubbled when on premo gas plus a plug change (plugs showed lean).
One thing that helps is add a 74 cent (wal-mart) yellow bottel of methal hidrate (methnol) gas deice to every 8-10 gallons of gas. Even with premo gas it realy fights detonation.
Japinese gas sucks the cheap stuff is rated with an octane of our premo gas and it won't even run in my little toyota with out detonating like crazy driving a slow speeds. It sucks.
I use AAFE's gas it's good I guess. D@mn good sense it's 93 octane and only 1.84 a gallon.
In big citys a lot of people think well kept and tuned sports/preformance cars make all the pollution when it's realy the junkers and the city busses that make all the smog.
All most any fuel injected well tuned N/A high preformance chevy or ford on premo gass can pass an emmisions test with out catalytic converters. But will fail when the smog guy dosen't see any cat.

[oil pan 4]

Here is the thred my post was from.
It also has national pump gas ratings on there.
http://forums.newbeetle.org/showthre...threadid=45362

[HAZ-Matt]

Is the rating of the Japanese gas just the research method? That would make sense since research ratings are higher than the motor ratings. We predominately use (R+M)/2.

[oil pan 4]

I don't know what its' problem is.
It might be becasue I played with the cam timeing and ignition so it runs real good with premo.
The japinese off base stuff runs like colman fuel in my car. It smells weard and detonates real bed.

[HAZ-Matt]

BTW I cannot see how running a motor naturally aspirated is going to be more efficient than a turbo motor in good tune. Sure, you may add a little backpressure but the turbo is going to make it much easier to take in the fuel/air mixture. I could very well be wrong on this count, and I am much more confident in my next points

Low octane is not really garbage gasoline. It's simply the mixture of hydrocarbons that gives a rating of 87. The higher octane fuels have most of the same alkanes/enes and aromatics that are in the low grade, just in slightly different proportions. They may also have more additives that will not burn as well as normal gasoline.

Theoretically, if a car is designed to run on 87 octane, raising octane number will not improve fuel economy, and in some cases can reduce economy. It really depends on the vehicles ability to manipulate the ignition timing. I have not seen statistically significant fuel economy increases or decreases with higher octane fuel in my Firebird.

Adding methanol will decrease fuel economy because per volume, methanol and ethanol both contain less energy than gasoline, (diesel contains more energy per volume than gasoline, which partially explains why a diesel model of a car gets substantially better fuel economy than the gasoline motors).

Your mom's Explorer should not have detonated on regular gas unless it was not designed for low grade, the gas you bought was bad, or some other factor was the real culprit. The octane of the fuel does not determine whether or not mixture will be lean. It is more likely that it is still lean but the higher octane is masking the symptoms.

[T-Punk]

i was always under the impression that a turbo got better gas mileage per hp than an na engine (ie a 300hp turbo car will get better mileage than a 300hp NA car).

[grayman]

Wow, this is getting good. I have read up on 87 vs premium gas just recently. HAZ-Mat is right on the money from all techy articles I have read. What matters most is what fuel the car is tuned for. (OEM) For instance, my internaly stock 2001 L36 is tuned for 87 octane. Putting higher grade fuel in car does not 'help' performance...unless perhaps there are some other issues with the engine. Higher octane fuel burns slower...that can ease detonation...but if a car is tuned for 87 and runs fine on 87...then use 87...it's cheaper. Throw Forced Induction (or high compression pistons such as 10/1) into the mix and you are most likely looking at higher octane as a requirement...for the slower burn....or retarding ignition more to compensate for all that cylinder compression that can 'pre detonate' the fuel mixture before top dead center on the spark stroke. Retarding the ignition hurts performance...so you can use higher octane fuel to compensate....
Regarding METHANOL: The owners manual for 2001 firebird specificaly says "Your vehicle was not designed for fuel that contains methanol. Don't use it. It can corrode metal parts in your fuel system and also damage plastic and rubber parts. That damage wouldn't be covered under your warrenty."

Ok, the owners manual also says for the 3800 v6 to use 87 ocatane or higher or 91 octane or higher for the 5.7L v8. (LS1 has 10/1 compression I believe.)

Thanks all BTW. Between science...".5 lb/hr of gas per hp with a turbo it takes about .6lb/hr of fuel per hp... and experience I think my basic question was answered. If a turbo puts me in the premium fuel league as well as yielding less fuel economy....I may be leaning more toward internals such as cam/valvetrain. (cheaper up front costs as well if i go without port and polish....i'm not taking off perfectly good heads with 7000 miles on them....no way. :) )

My next questions will pertain to passing emissions with modified internals. (has been covered many times before.... I know...but posts always seem to get off topic...)
;)

[oil pan 4]

A 1991 ford explore shouldn't be undirvable on 87, that is what the owners manual says it should take.
Driving 90mph+ on the inter state at 4000rpm and 3/4 to WOT all the time for 90minutes the reg gas couldn't handel it. Maybe the ford 4.0L V6 just plain sucks.
The Only way to know for sure on your car is to do a mileage test.
I think every one should try it.
On some cars even with the extra cost it is worth runing it because of the gas milage is so much better.
If you like spending extra money to burn loads of cheap dirty fuel that gets you far less gas milage than the good stuff go ahead and do it. It isn't my money.
87 octaine is faster burning and has more BTU's it is made of more hexane. The hexane burns realy fast and uncontroaled. If you have a lower C/R (>9:1) carbed (carbs tend to run rich if you want them to) car it will most likly run better on reg.
Cars don't have 8:1 C/R's any more and run lean from the computer (I think 14.7:1 A/F is lean, it makes NOX but the cat cleans up that little mess). Alot of newer cars have fast buring head designs, it is not a good idea to burn fast burning fuel in a fast burning head design and some times it needs to be slowed down.
Adding methanol with and keeping it less than 1% hasn't hurt any thing over here.
So Toyota and ford fuel systems must be better than chevy fuel systems if every one thinks the chevy fuel system will die at the first hint of methal hydrate.
It rains and snows all the time over here and I put it in my little car all winter.
I'm sure I could get a 7.6:1 C/R 3600rpm dump truck engine that gets better gas milage then a normal car on reg gas.
A small engine 300hp turbo car will get better gas milage dirving around because you are not useing boost and are useing less cubes to drive around.
All moter cars burn less fuel per hp that's all there is to it.
If you have to boost to maintain higher say inter state speeds say 80mph you can kiss the good gas milage good by.
To pass emmisions you will have to have it tuned good that's all there is to it. It takes C/R, the right cam, ignition timing and fuel also.
A turbo diesel will get better gas mileage compaired to N/A. They get free power from a turbo insted of spewing black smoke like they do N/A that smoke gets burned when boosted. They need a little back pressure to run good it seams , diesel engines are all I work other than gas turbines I know them both very well. When you boost them you don't have to ajust any ignition timing or have any uncontroaled detonation. They just run better with a trubo and there simple you don't need any kind of wasted gate in most cases or a BOV.

[Turbo V6 Camaro]

my car before the rebiuld

87 :puke:
89 ok
91 ok
92 [img]graemlins/banana.gif[/img] [img]graemlins/rock.gif[/img] best MPG (shell gas was even better)
93 ok waste of monye lost MPG

[oil pan 4]

The ford was like [img]graemlins/barf.gif[/img] on 87.
With 89 it was kind of [img]graemlins/stickpoke.gif[/img] with 89, still sucked.
When I did a cheap @ss CAI mod, changed plugs and used 92 gas w/1% methel hydrate it bounced off the speed limiter (105 I think is is set) going down the inter state I was [img]graemlins/rock.gif[/img] all the way.
The LG4 is carbed and has a 9.5:1 c/r.
My Z28 hates 87, I use mid grade and it likes it.
I filled it up and drove it some before I put it away for another year+ with premo gas, couldn't tell much difference from premo and mid grade.

[grayman]

oh, yea, I agree on theory of testing mpg with differet octanes. thanks for the reminder. i plan on testing it stock/unmodifeid as well as using the hypertech pp3 to tune for 92 octane. this will take a few tanks of gas....but my wallet never seems to be more than a few feet away from my gas tank.
You guys have given a lot of great info and real life experiences. it's always better to be informed than to take things for granted.
Slightly off topic: Prior to 'reading up' on the subject and by no means an export now...I have heard from more than one sorce that it costs the same amount of money for oil refineries to make premium grade fuel as it does to make lower octane fuel. If all thay made was premium gas...and all new cars were tuned to utilyze premium gas....wouldn't that improve performance aka gas mileage and create less pollution overall...generaly speaking? When it comes to things like pollution it is ok to make laws and force big companies to get with it. That opinion is coming from a libertarian type person.
But big emission states like california limit the octane levels of gasoline...arghh...I guess I am just not a fuel/emissions scientist.

[HAZ-Matt]

It does in fact cost the refinery the same amount of money to refine each grade of gasoline. However it would be more expensive to refine only one grade because you would have all of the hydrocarbons that you could not mix to get your one and only octane rating.

Methanol or ethanol in small concentrations probably won't damage the fuel system, but methanol is in fact corrosive to rubber and plastics.

Also, slower burning fuels are more likely to avoid burning especially under light load. The you have hydrocarbons coming out of your tailpipe for no good reason. That partially explains why California has lower rated numbers. The most important factor is that I think California mandates a lot of anti-pollution additives that tend to drive down the octane numbers.

87 octane does not have more BTU's on average than 89 or 93. The reason it is more burn resistant is simply that the hydrocarbons in the mixture are less reactive (ie their combustion reactions have higher activation energies). The BTU rating for essentially all gasoline in the US is 125000 BTU/gal. While both octane rating and energy content depend on the actual mixture in the gasoline, there is no definitive relationship between them. It is quite possible and likely that two gallons of gasoline with the same octane rating will have different energy contents. (Oddly enough, energy content does in fact positively correlate with 2,2,4-trimethylpentane content, but since it is not necessarily the main component of higher octane fuels it is of little consequence.)

Interesting tidbit. The term "octane rating" is slightly deceptive if you are well versed in IUPAC nomencalture because the reference for the rating is really a 2,2,4-trimethylpentane (isooctane in the older nomenclature) and heptane (n-heptane) mixture.