How to make an efficient engine

[doclees]

I know this might be sacrilegious to even ask but what can be done to make the SHO engine more efficient? Yes park it and don't drive it, stay off the gas, only go down hill, etc.... I make the assumption that things that remove restriction will, such as exhaust and headers. What about air flow in? I read that when all thing are equal and you increase the intake length you improve air/fuel mix which improves torque. If this is so does this mean you move more weight with the same fuel?
Thanks

 

[rubydist]

some have reported better mileage with newer style injectors that do a better job of atomizing the fuel, but you need to tune the engine for the new injectors, and you have to save a lot of gas to pay for all of that.

some have reported slightly better mileage with the cop modification, but others have not.

headers on the SHO motor have proven to lower power and lower mileage in street applications.

the length of the intake runner is tuned to a desired torque peak - the SHO motor has dual length runners to allow for 2 torque peaks due to the longer and shorter runner lengths. if you lengthen the runners, you reduce the rpm of the torque peak.

the air/fuel ratio needs to stay at 14.7 for "normal" use, only going richer for wot usage. making the engine run leaner will only make emissions higher, although slightly leaner will provide better fuel mileage.

 

[pjtoledo]

I know this might be sacrilegious to even ask but what can be done to make the SHO engine more efficient? Yes park it and don't drive it, stay off the gas, only go down hill, etc.... I make the assumption that things that remove restriction will, such as exhaust and headers. What about air flow in? I read that when all thing are equal and you increase the intake length you improve air/fuel mix which improves torque. If this is so does this mean you move more weight with the same fuel?
Thanks

works great with carburetors. our the fuel injectors are at a fixed distance from the intake valves for both sets of runners.
more efficient at doing what?? mileage? low end torque? hi end torque? a higher restrictive exhaust can slow down scavenging, thus waste less fuel during scavenging and yield better low rpm mileage. but choking off the scavenging totally kills hi rpms.
better computer tunes and variable cam timing is what the latest engines use to broaden the powerband.


Perry

 

[luigisho]

magnets

 

[Eric VerValin]

Underdrive pulleys.

 

[SHOCH]

VooDoo and praying to the rock God Lemmy.

 

[Enzo731]

you'll spend less making a more efficient driver behind the wheel, than an efficient engine.

maintain your car properly and it will achieve close to what was first advertised on the window sticker, maybe more!

 

[TwistedD85]

magnets

How does that work?

 

[gmail]

you should be able to get up to 30 mpg already whats the problem?

take care of the car and drive it nice and it will get good mileage..

any intake/exhaust/ lightening mods will increase fuel mileage.

whats the rule of thumb. every 100 lbs is .02 in the quarter mile.
now imagine that in fuel mileage also.

if you play with tuning theres a ton of things to do to get better mileage. like was said going leaner will help tons.
you can go as far as 16+ afr and get a very noticable difference in mpg just make sure its only light throttle and not under load or you can start to hurt stuff.

the injectors i was looking into testing out from 96+ tauri shouldnt need tuned. they will be only slightly bigger which the computer will learn that on its on so in reality no tunning should be needed to get them to work properly.

area91 makes over 300+ hp on bolt ons alone and reported 30 mpg on his trip to CA

 

[doclees]

more efficient at doing what?? mileage? low end torque? hi end torque?
Perry

Gas mileage.

scavenging - thanks for the new term. Looking to more or less keep the basic characteristics of a stock engine but am willing to lose some HP to gain gas mileage.

So far things are adding up that my 3.2 will be going into a pre 75 Triumph Spitfire body with about 1000# less. It will have more than enough power for me even if it was only 150hp. Like to see how much gas mileage on a highway trip is possible out of these engines. I suspect no cats will be needed with this year body.

I have gotten 31 mpg on my 89 before the clutch/fidanza flywheel/rod bearing job. Haven't had any long runs yet. I do have a K&N with an older higher flow y pipe. Can't remember the make.

Don't want to change anything that would compromise the reliability of the engine. I had a 73mm MAF that made ping like crazy. Pulled that fast.

 

[93rev2sev]

whats the rule of thumb. every 100 lbs is .02 in the quarter mile.
now imagine that in fuel mileage also.

Every 100lbs is worth .1 in the quarter.

 

[luigisho]

How does that work?

http://www.popularmechanics.com/cars/alternative-fuel/gas-mileage/1802932

 

[kevinspann]

magnets

Problem?

 

[gmail]

you could always go the more expensive route and do it up like the metro did for a short time.. the 3 cly metro had lean tuning, and ran only 1 compression ring for less drag and that thing got 65 mpg.. i almost bought one before but it was rotted out where the tiny engine bolted in... im sure i could have used dental floss to hold it up but wasent interested

now that would require lite weight special pistons to get that but its doable..

 

[doclees]

you could always go the more expensive route and do it up like the metro did for a short time.. the 3 cly metro had lean tuning, and ran only 1 compression ring for less drag and that thing got 65 mpg.. i almost bought one before but it was rotted out where the tiny engine bolted in... im sure i could have used dental floss to hold it up but wasent interested

now that would require lite weight special pistons to get that but its doable..

Interesting idea. Wiki says the EP highway rating of 51 for the detuned 3Cly engine vs 45 for the non-detuned engine. If the less compression ring was the major diff between motors it is only a 10% gain mileage and a 10% loss in HP. Since this will be a RWD I wonder how much gain could be expected with 1000# less and a drop in rpm's to about 1800 at 65 mph.

 

[pjtoledo]

Problem?

it needs to be on a swivel mechanism. for stopping point it to the rear.

 

[pjtoledo]

Gas mileage.

scavenging - thanks for the new term. Looking to more or less keep the basic characteristics of a stock engine but am willing to lose some HP to gain gas mileage.

So far things are adding up that my 3.2 will be going into a pre 75 Triumph Spitfire body with about 1000# less. It will have more than enough power for me even if it was only 150hp. Like to see how much gas mileage on a highway trip is possible out of these engines. I suspect no cats will be needed with this year body.

I have gotten 31 mpg on my 89 before the clutch/fidanza flywheel/rod bearing job. Haven't had any long runs yet. I do have a K&N with an older higher flow y pipe. Can't remember the make.

Don't want to change anything that would compromise the reliability of the engine. I had a 73mm MAF that made ping like crazy. Pulled that fast.

as light as that vehicle will be, the final gear ratio will make a huge difference in mileage

 

[NovaSS]

The problem with "off shelf " headers for the sho is they are too short and primary diameter is too large for low rpm gains .

I would love to see some properly build headers on a sho to see what they do for low end grunt. maybe 1.5 diameter and 30 + inches

 

[Twisted6]

The problem with "off shelf " headers for the sho is they are too short and primary diameter is too large for low rpm gains .

I would love to see some properly build headers on a sho to see what they do for low end grunt. maybe 1.5 diameter and 30 + inches

1.5" diameter is still too large. NHRA and IHRA stock teams run 1.5" primaries. I would vision more in the 1" to 1.25" range. THE man to do your headers is Jack Burns of Burns Stainless Steel. Give him all of your engine details and what kind of space you are working with and $75 later he has a design custom tailored to your specific engine and application, ready to transition into the real thing.

 

[1slickRED89]

31 MPG is pretty good. only going to get marginal improvements without huge modifications.

the only cheap and effective 'mod' i can think of would be tuning to run lean at part-throttle. it would take ALOT of tuning work to get it to run smooth. lean at full throttle you will lose lots of power, but you will find quite a bit of efficiency going to lambda = 1.2 or so (~17:1 AFR) at cruise. the reason is because the engine will make less power and so you have to push the throttle in more, which reduces the engines pumping losses. you may get up 5% thermal efficiency gains, which is maybe 1-2 MPG or so. at part throttle most engines are in the 12-19% BTE (brake thermal efficiency) range whereas they are near 29-30% at WOT. so there is a lot of losses running the engine at low power, the most efficient way to make a given amount of power is running a small engine at higher loads than a big engine at low loads.