TeamSwift

Home of the Suzuki mini-compacts ! Your Home for all things Suzuki Swift, Geo Metro, Holden Barina, Chevy Sprint, Pontiac Firefly, and Suzuki Cultus. TeamSwift is a technical performance oriented community!
It is currently Mon Oct 23, 2017 1:20 pm

Underbody braces, turbos and more!

All times are UTC - 5 hours




Post new topic Reply to topic  [ 64 posts ]  Go to page 1, 2, 3  Next
Author Message
 Post subject: Free MPG ideas?
PostPosted: Sun Sep 23, 2007 11:58 pm 
Offline

Joined: Mon Jun 06, 2005 8:19 pm
Posts: 274
Location: Vancouver
Hey guys, I'm on a quest to get as much fuel mileage out of my '99 1.0L for as little as possible and I wanted to know what you guys think of what I'm planning on doing and if you had anything to add to my ideas. I average 45mpg to and from work and my best average to date was 53 mpg on my summer camping trip! So far I've got a TBI and intake manifold for free and a free cylinder head on the way as well. I was thinking about port matching everything, removing any imperfections in the runners and increasing the compression by milling the head down .040" or so. Next I will make some aluminum pulleys and possibly an aluminum flywheel if I have time. I was also thinking about boring the TBI but I wasn't sure if that would help or hurt mileage? I don't think this will help much but if I can get an exhaust manifold for free I will port/polish it and ceramic coat it at my work. I can't do too much to reduce the weight because I still want it to function as stock but I might look at improving the aerodynamics a bit. I'll update this post with my progress. What do you guys think?


Top
 Profile  
 
 Post subject:
PostPosted: Mon Sep 24, 2007 12:02 am 
Offline

Joined: Mon Jun 06, 2005 8:19 pm
Posts: 274
Location: Vancouver
I just thought of a couple things... is there anything I can do to the combustion chamber to improve the combustion? Or how about making solid or poly motor mounts to transfer a greater percentage of the energy to the transmission, making it more efficient?


Top
 Profile  
 
 Post subject:
PostPosted: Mon Sep 24, 2007 2:12 am 
Offline

Joined: Sun Aug 20, 2006 11:31 pm
Posts: 57
Location: Lummi Island
Metro Muscle wrote:
I just thought of a couple things... is there anything I can do to the combustion chamber to improve the combustion? Or how about making solid or poly motor mounts to transfer a greater percentage of the energy to the transmission, making it more efficient?



Look up "Singh Grooves" they are easy to cut into the head and will allow higher compression and more advance without pre-detonation.

MM


Top
 Profile  
 
 Post subject:
PostPosted: Tue Sep 25, 2007 12:25 am 
Offline

Joined: Mon Jun 06, 2005 8:19 pm
Posts: 274
Location: Vancouver
Wow, that almost seems to good to be true! I wonder if he discovered that on purpose or if he slipped when he was porting his heads or something :lol: Seems like if you went too deep it could weaken the head pretty significantly :?


Top
 Profile  
 
 Post subject:
PostPosted: Thu Sep 27, 2007 3:46 am 
Offline

Joined: Mon Sep 24, 2007 8:03 pm
Posts: 43
I'm an old two stroke fanatic from back in the mid 70's, I had a Yamaha RD350 two stroke twin street bike that would turn 13.99 @ 92 mph in the 1/4 mile.

One trick to getting a two stroke to make more power (who gave a crap about fuel efficiency in the 70's?) was to get the squish area in the combustion chamber as tight as possible. As the piston approaches TDC, the fuel/air mixture in the squish area is squeezed out into the rest of the combustion chamber in a sort of jet, increasing the turbulence of the mixture. The thinner the squish area is the greater the jet speed.

Increased turbulence makes for a faster flame propagation throughout the combustion chamber and increases the efficiency of the combustion process which increases torque and horsepower.

Since the squish is most pronounced at or very near TDC, the combustion speed is increased just before and after TDC, which makes the fuel/air charge release more of its energy right around TDC, thus making sure that more of the energy released is used to push the piston down rather than fighting it on the way up.

In engines that are going to operate at high rpm, rod stretch is a problem as the piston decelerates moving toward TDC, thus you cannot make the squish zone as thin as you would like because it could lead to the piston hitting the cylinder head. In an engine that is not going to be operated at high rpm you can therefore tighten the squish more than you can for a high rpm engine.

With thin squish zones, the timing has to be retarded somewhat which, when you have increased the burn speed, also contributes to fuel efficiency by keeping the portion of the charge burn before TDC to a minimum.

Of course, thinning the squish zone so much is going to increase the compression ratio, possibly so much that detonation will occur even with high octane gas. The solution to this is to sink your valves into the head a bit further, thus increasing the combustion chamber volume and lowering the compression ratio. You will want to cc your heads and match the chamber volumes for greatest benefit.

There is going to be a delicate balance between compression ratio, charge turbulence and fuel octane. The only way to determine this balance is via trial and error.

In general, anything you can do to to increase the charge turbulence in the chamber would increase efficiency and thus fuel mileage.

This means that porting and matching the intake ports is probably not the best idea in an engine designed for maximum fuel mileage, which is going to be accomplished at as low an rpm as possible. The main reason for porting and polishing the intake is to increase the absolute flow capability of the port thus increasing the horsepower in the upper rpm range by the simple expedient of cramming more charge into the cylinder.

Charge turbulence is increased by smaller and rougher ports, not larger and smoother ones. Polishing increases the percentage of laminar flow in the port, thus decreasing the turbulence in the charge.

In fact *reducing* the size of the intake port would probably be a good idea in an engine designed for low rpm efficiency. This will maximize intake charge velocity which will lead to more efficient cylinder filling at low rpm.

A step between the intake manifold and the intake port will also probably increase charge turbulence. Make the portion of the intake manifold port just before the transition to the cylinder head larger in a smoothly tapered cone shape such that, at the transition, it is larger than the portion of the intake port in the cylinder head. This step will further increase intake charge turbulence.

On the other hand, polishing the exhaust port is probably a good idea, you want maximum laminar flow in the exhaust in order to minimize turbulence and increase flow rate in the exhaust system. Enlarging the exhaust port will increase flow but lower exhaust velocity which may actually decrease exhaust gas speed and decrease cylinder evacuation.

Furthermore, anything you can do to keep the exhaust flow gas as hot as possible will lead to increased exhaust velocity and better cylinder evacuation. The more efficiently the cylinder is evacuated, the less diluted the intake mixture becomes with combustion products. This means that insulating the exhaust system in order to keep the exhaust temperature as high as possible will probably increase overall efficiency at low rpm's in particular.

A high exhaust speed, low restriction exhaust is wanted for low rpm efficiency so you will want to put as low a restriction muffler as you can find while still keeping exhaust diameter small.

All these steps, in conjunction with the Singh grooves (which I have never heard of before), would quite possibly greatly increase low rpm combustion efficiency.

I'm interested in this subject and welcome discussion of, and particularly disagreement with, my ideas that I may further my understanding of these factors.

Peace,

Jon


Top
 Profile  
 
 Post subject:
PostPosted: Thu Sep 27, 2007 4:58 am 
Offline

Joined: Mon Sep 24, 2007 8:03 pm
Posts: 43
After thinking about it for a while I have come up with another old trick to help combustion efficiency. Coating the inside of the combustion chamber and the piston crown with a white, flameproof coating has been done for many years now, particularly in drag racers. This helps keep the heat in the combustion gases from being transferred to to piston and cylinder head which increases the temperature of those combustion gases. The hotter the gases remain, the greater amount of the energy that can be directed toward pushing the piston down instead of heating the piston and cylinder head.

http://www.swaintech.com/store.asp?pid=10322

Another thought that has come to me upon reflection is that the theoretical efficiency of a Carnot cycle engine is determined by the *difference* in temperature of the cold and hot portions of the cycle. This means that keeping the intake charge as cold as possible would probably contribute to increased efficiency. This means a cold air intake on top of the hood (the air is hottest closest to the ground) and insulating the intake manifold and all intake air piping.

It also occurs to me that camshaft profile and timing have a great deal to do with the torque peak of an engine. You may wish to have a custom cam ground for you engine and incorporate some means of adjusting the cam timing. For maximum torque at low rpm you will most likely want a shorter duration cam with lower valve lift. The shorter duration will increase low rpm torque by allowing more of the compression stroke to actually compress the charge rather than having it leak out of the valves during valve overlap time. The decreased lift will increase intake charge velocity by the valve and further contribute to turbulence in the combustion chamber.

Peace,

Jon


Last edited by Soliton on Thu Sep 27, 2007 7:36 am, edited 1 time in total.

Top
 Profile  
 
 Post subject:
PostPosted: Thu Sep 27, 2007 5:17 am 
Offline

Joined: Mon Sep 24, 2007 8:03 pm
Posts: 43
I started reading the forums on Mr Singh's website and came across this:

http://jeremiahsviolins.com/grooved2.htm


Top
 Profile  
 
 Post subject:
PostPosted: Thu Sep 27, 2007 9:45 am 
Offline

Joined: Mon Sep 24, 2007 8:03 pm
Posts: 43
One more thing, it would be nice to be able to measure the torque and horsepower right in the car before and after modifications.

Take a look at this:

http://returnsforsale.com/cart.php?m=pr ... etail&p=78


Top
 Profile  
 
 Post subject:
PostPosted: Sun Sep 30, 2007 2:32 pm 
Offline

Joined: Mon Jun 06, 2005 8:19 pm
Posts: 274
Location: Vancouver
Wow, thanks for the info Jon, that definately gives me something to think about. Part of my quest is to get a little more performance as well, so finding the balance between power and economy might be a little tricky but I'll keep you updated on the progress. What do you think about reducing rotaional mass for economy and power?


Top
 Profile  
 
 Post subject:
PostPosted: Sun Sep 30, 2007 9:02 pm 
Offline

Joined: Mon Sep 24, 2007 8:03 pm
Posts: 43
In general, higher rotating mass leads to a smoother running engine at low rpms, which is the reason that manufacturers make the flywheels as heavy as they do.

Lower rotating mass is going to help the engine rev up more easily, but in an engine designed for fuel economy you will be revving the engine as little as possible.

On the whole I think the heavier rotating mass is going to be better for fuel economy because it will allow you to let the motor run at lower rpms in a higher gear without bucking and jerking.

Another thing to consider is ignition. The hotter and longer the spark across the spark plug gap, the more efficiently and thoroughly the fuel/air charge will be ignited.

http://www.msdignition.com/ignition_1_5900.htm

Quote:
The Blaster creates a high current, long duration spark that efficiently burns the air/fuel mixture in the cylinder. The benefits are more power, easier starting, snappy throttle response and increased mileage. This single spark ignition will install easily to breaker points, late model computer equipped vehicles and magnetic pickup distributors such as the line of MSD Pro-Billet Distributors.


Another point I forgot to mention about tight squish areas is that not much combustion takes place in the squish zone, so the tighter the squish the less unburned charge there will be left in the squish.

A hot, long duration spark combined with tight squish, Singh grooves and the other modifications I mentioned should significantly increase the efficiency of almost any engine.

My brother and I had an old Dodge D600 dump truck about ten years ago. It had a massive 361 gas V8 that was a bear to start and keep running when it was cold, you had to rev it continuously until it warmed up.

Bro had an early MSD ignition that had come off a hot rod which had blown the engine. We took the MSD off the hot rod and put it on the dump truck. The transformation was amazing, you could pump the carb about three or four times, hit the starter and it would crank immediately and after about ten seconds of moderate revving it would settle down to a surprisingly smooth idle.

Think of how well the Singh grooves will work with a long duration hot spark. The grooves don't just squirt out an instantaneous jet but rather the jet increases in velocity and strength as the piston approches TDC. If the spark is firing continuously during this time then the charge being jetted at the plug is continuously lit. The burn efficiency gain should be considerable.

You might also want to consider indexing the spark plugs in such a way that the outer electrode is not in the way of the jet from the Singh groove.

Peace,

Jon


Top
 Profile  
 
 Post subject:
PostPosted: Tue Oct 02, 2007 10:20 pm 
Offline
User avatar

Joined: Sat Jun 03, 2006 11:54 pm
Posts: 673
Location: Illinois
They are doing these with success over at the mpg research forum.
Image

The object is to induce turbulence that disperse and further mix the A:F ratio, making it more easily consumed during combustion. It's basically screw threads machined into the intake port. It could be done the whole length of the intake tract, because it injects the fuel at the TBI. It could be done with a cutoff wheel and a dremel.

Their website.

http://www.mpgresearch.com/index.php

_________________
If it ain't broke, fix it until it is. LOL.


Top
 Profile  
 
 Post subject:
PostPosted: Wed Oct 03, 2007 8:52 am 
Offline

Joined: Mon Sep 24, 2007 8:03 pm
Posts: 43
A couple more thoughts.

Reduce the size of the intake port just before the valve with something like jbweld. Roughen the jbweld while it sets with some kind of tool, even just the head of big nail chucked in a drill. Most of the length of the intake port could be done this way. Smear a fairly thin layer of jbweld and then put nice gouges in it while it sets. Start off deforming it gently when it's wet and then harder as it dries.

Once the jbweld is shaped and roughened then use more jbweld to attach small plastic L shaped tabs. Put the tabs face on to the incoming f/a charge. More turbulence.

Roughen the back side of the valve. More turbulence.

High velocity turbulent flow in, high velocity laminar flow out.


Top
 Profile  
 
 Post subject:
PostPosted: Wed Oct 03, 2007 11:10 am 
Offline
Bozo the crying clown

Joined: Tue Mar 13, 2007 9:19 am
Posts: 414
Location: Chester County PA
Not to be a d1ck....but what would happen if the JB weld came loose?

new motor???heheheheheheh


Top
 Profile  
 
 Post subject:
PostPosted: Wed Oct 03, 2007 7:20 pm 
Offline
Suzuki Elder
User avatar

Joined: Mon Dec 01, 2003 12:47 pm
Posts: 11669
Location: columbus, ohio
please don't take this as flame, i appreciate a discussion as well.

first off, i'm an old stroker fan myself with motorcycle and vintage auto creds.

the squish band that you describe is very much a part of schnurle principle 2 stroke technology, it works great - on 2 stroke designs. the combustion chamber design of the suzuki variants is physically much different. the stroker head will usually have a hemispherical design (dome in the center of the chamber with a spark plug in the center) which uses a purpose designed, squish ring around the circumference of the bore and flat or very slighty dome piston faces. the suzuki designs have a combustion chamber that has a dome shaped relief that covers the entire cylinder bore, allowing room for valves to open into the head. the spark plug is off to one side between the valves (excepting the twincam which has it's plugs centered among 4 valves.) the pistons are largely flat and are relieved to allow valve clearance. there is really no way to incorporate a squish area on the suzuki 4 stroke engines.

the schnurle principle 2 stroke as well as the 4 stroke engine will not benefit from turbulence in the combustion chamber. as a matter of fact, turbulence in the combustion chamber is detrimental to moving air into and out of the chamber with efficiency. you would absolutely maximize flow to be as close to laminar as possible as far as flow into the combustion chamber, out through the exhaust ports, and thru the exhaust manifold.

in the case of the schnurle principle 2 stroke design, you need to design a return pulse or "echo" in the exhaust flow which aids in "stuffing" fresh charge that has overflowed the combustion chamber, back thru the exhaust port just before the piston comes up in the chamber and closes off the port. the 4 stroke engine doesn't need to do that. it has a valve which automatically regulates the flow. even though the exhaust on a 4 stroke engine emulates the "echo" to some degree and some engines benefit to some degree from the pulse slowing exhaust gas movement in the exhaust manifold, largely, the most efficient engines keep the hot gas moving towards the atmosphere at the end of the pipe.

i've always thought that the ablative or insulating combustion chamber coatings were a bandaid for bad engine designs compounded by a lack of thoughtful tuning. i don't include treatment of the pistons in that description. piston faces take some serious punishment from fire deck temps in normally aspirated engines. pressurized induction and oxygen enrichment (nos) really subjects the pistons to hellfire.

in a schnurle principle 2 stroke configuration, induction is accomplished by drawing air into the engine's crankcase through rarification of the bottom chamber when the the piston ascends in it's bore. sometimes it's aided by webs or notches designed into the crankshaft. it is also this atmospheric rarification which causes droplets of lubricating oil to reach their pressure/ vapor point and transform into a mist which mingles with the gasoline in the air/ fuel charge. then primary compression is generated in the crankcase chamber when the piston descends and forces the air/ fuel/ oil mixture to move to the combustion chamber via the transfer port, that transition is aided by runner ports that are as smooth as is possible so as to not perturb the flow - laminar is a good thing here.

in the analog of that, the transfer of air/ fuel charge in the 4 stroke is similarly aided by a smooth transfer to the combustion chamber. it, however, lacks the mechanical advantage of the rarification process of the stroker design. that means that droplets of fuel don't necessarily bloom into mist. that's not great for combustion. to achieve the much smaller droplet size, in the throttle body design intake, suzuki uses heated intake manifolds and casting techniques which leave textured runners to help break up fuel droplets. some other engines use screening across intake ports and sharp steps. here, you're not looking for a lot turbulence. it's more like a jostling of the boundary layer of air flow. in the dohc design, the intake manifold suffered from less than smooth intake runners and plenums. you want all those surfaces to be as smooth and lightly transitioned as possible to enhance flow. the 4 fuel injectors on the twincam have orifices which are designed and optimized for droplet size and spray pattern which is then introduced at the end of the intake runner and close to the combustion chamber.

one last thing. the ignition systems on all the suzuki variants are pretty darned good and hard to improve on without throwing down a wad of cash. good high tension leads and v-groove or u-channel type plugs are, in most cases, the only things you need to upgrade. dwell is handled electronically.

because i can come across rather harshly at times, so as to not ruffle anybody's feathers, i offer this post as a point of discussion and not as a flame. don't be unsettled if i disagree with something that has been said. lively discussion is encouraged. :lol:

_________________
1991 Blue Geo Metro Convertible highly modified 1.0L Turbo3 5 spd. - 1991 Red Geo Metro Convertible customized with a Twincam 5 spd.

My Turbo3 Project
My Cardomain Page -Ol' Blue
My YouTube Channel
My Photo Gallery
SAAB Sonett II


Top
 Profile  
 
 Post subject:
PostPosted: Thu Oct 04, 2007 5:38 am 
Offline

Joined: Mon Sep 24, 2007 8:03 pm
Posts: 43
No problem...

A schnurle two stroke has ports that basically swirl the fuel/air charge into the chamber in three or more loops. The turbulence from the squish band in the combustion chamber occurs well after the piston has closed the ports. By that time, the engine doesn't really care whether it is a two stroke or a four. All the chamber knows is it's sealed and there's a piston coming up. The turbulence caused by the squish bands doesn't start to happen until the piston is only a hundred thousandths or so from TDC

As far as Suzuki four strokes go, I was just giving general advise according to what I have learned as the principles of four stroke motors.

Indeed, for maximum horsepower you want laminar flow in and laminar flow out.

For fuel efficiency though, what is wanted is as thorough a mixture of fuel and air as can be managed. Overall horsepower is not as important as fuel efficiency and smooth torque at low rpm.

A relatively unmixed fuel/air charge has pockets of leaner and richer mixture. Those pockets of mixture most likely to detonate do so as the absolute pressure increases while the piston rises toward TDC.

The more thoroughly mixed the incoming charge the less the tendency to detonate.

I see the use of combustion chamber coatings as addressing a basic problem of i/c engine design. The ideal chamber would be perfectly insulating to allow the maximum use of heat energy go into expanding gases rather than heating the cylinder.

If you look carefully at the ignition I linked to you'll see that it's a piggyback unit which goes in parallel with the stock ignition. What it does is increase the spark duration to twenty degrees of crank rotation.

Does the stock ignition just fire one short spark or does it have variable length spark that always fires for twenty degrees of crank rotation?


Top
 Profile  
 
 Post subject:
PostPosted: Thu Oct 04, 2007 3:24 pm 
Offline
Suzuki Elder
User avatar

Joined: Mon Dec 01, 2003 12:47 pm
Posts: 11669
Location: columbus, ohio
i understand that you want some perturbation of airflow to mix fuel and induction air in certain instances. a carbureted induction set, a throttle body injected intake - they benefit up to a point but they are pretty old technology. sometimes an engineered swirl, say, in an air filter box helps to keep air velocity up but every application of that which i've seen in old saabs and dkws utilized smooth, fabricated steel and was applied prior to the carbs.

what i'm saying is that going to great lengths to upset flow going into the cylinder is counter productive. there is absolutely no reason to rough up port walls with a the twincam, droplet size is achieved by using the individual injectors. as a matter of fact, you want the port runners and plenum walls of the intake manifold to be very smooth so as to minimize the perturbation of the induction charge.

from my standpoint the description and photograph of the knurled port runner is over the top and would severly affect air flow at the wall boundary layer to the point of being counter productive to engine efficiency. what you are losing in efficient transfer of the charge cannot be recovered by minimizing droplet size or a higher degree of blending. technology to provide atomization of liquid was produced in the early to mid 80s (i helped to design medication atomizers back then) and has been applied to automotive designs for years - it just isn't technology that's used with primitive carburetor designs. since i have some real hours in flow technology at a thermal dynamics lab, i have a pretty good feel for what is beneficial and what is "magic" bullsheist. if boundary layer perturbation and designing away from laminar flow was all that and a bag of chips, modern casting and vapor deposition technology would be looking at ways to produce rougher finished products instead of smoother ones.

a designed squish band is productive in a hemispherical design 2 stroke engine. it's also less effective in a non-hemi design and is rarely included in a standard 4 stroke engine because it is of little benefit.

i tweaked a saab 843cc 3 cylinder 2 stroker to 940cc and threw every factory rallye spec trick at it including the tedious job of finessing a 1mm squish band in each cylinder. along with everything else, i locked down the distributor advance so that it would never trigger a spark event before TDC. to do so in a highly tuned engine like that would have hammered the needle bearing cages in the big and small ends of the connecting rods to hell and gone.

for anyone who is interested in 2 stroke engine principles, i suggest a trip to the library (the book is long out of print) to check out a primer from a. graham bell. it is considered "the bible" by most stroker enthusiasts.

i'm well aware of the multiple spark discharge designs from MSD and other drag racer oriented manufacturers and would agree in principle with their design function. it's just that the stock suzuki ignition designs are really solid and provide a suitable flame propagation for their engines. you start to have problems with the flame front when you start to utilize "pop-up" pistons and the like and most tuners will do things like drilling holes for second spark plugs (ala harley davidson tuners) to ensure a complete burn and faster ignition events. it has a lot to do with combustion chamber geometry and piston shape. the suzuki designs generally use flatter piston crowns and don't suffer from incomplete fuel burning to begin with so there is little to gain by trying to fix a problem that isn't there to start with. a multiple spark ignition system is better applied to an engine with obtuse piston geometry and for economy, i don't think the multiple spark units are all that for increasing mpg on a suzuki g series engine.

things change on that issue when you're looking at forced induction or chemical o2 enrichment designs.

ablative and insulating materials used in a combustion chamber to control effects of elevated temps (fire deck temps to be precise) are just patches for a poor choice of base materials, rotten designs, or imprecise tuning that allows fire deck temps to exceed design. anyone who does that as an engineering solution has decided that the trade off (usually monetary) warrants using the "fix." automotive design engineers will build in a percentage of safe area of operation of maybe 20% through the specification of materials including factoring fire deck temps. porsche for example (and volkswagon with their air cooled engines) had specs that limited temps so that they would ignite metal fires in their aluminum alloy engines. i've seen a bunch of vw hippy buses in flames on the side of the road when some "super tuner" exceeded the safe area of operation designed into the engine. metal fires are spectacularly sparkly and bright. :twisted:

the reason i like v groove or u channel spark plug technology is that high voltage really loves sharp edges and will provide a better spark event from those sharp edges. on that point, i find that the small increase in price is beneficial for improving combustion. still, we aren't talking hundreds of dollars as with the addition of an MSD unit or a similar control. the same goes for good ignition leads. you get what you pay for when it comes to the plug wires.

i really only comment on things i've tried and stay away from remarking on things i've read about. i usually carefully weigh any theories when it comes to engine design and tuning and try to reach an informed conclusion on benefits and how it will fit into an overall balance of design before i undertake any execution. from everything i've ever done in the field of flow, roughening up passage walls would be the last thing i'd ever do to increase efficiency. i think it's a bad plan to trade efficient flow for fuel/ air mixing. there are better scientific options to acheive that and suzuki incorporates some of them in their designs. if it was an efficient trade-off, you'd see some really bad castings coming out of the factory.

to support my opinion, check out some of the smoothing and surface blending that jardamuth has done in his intake manifold designs for the suzuki machines. if smoothing and polishing wasn't productive, i don't think he'd be doing it.

_________________
1991 Blue Geo Metro Convertible highly modified 1.0L Turbo3 5 spd. - 1991 Red Geo Metro Convertible customized with a Twincam 5 spd.

My Turbo3 Project
My Cardomain Page -Ol' Blue
My YouTube Channel
My Photo Gallery
SAAB Sonett II


Top
 Profile  
 
 Post subject:
PostPosted: Thu Oct 04, 2007 6:05 pm 
Offline

Joined: Mon Sep 24, 2007 8:03 pm
Posts: 43
When you roughen the intake port wall you thicken the boundary layer. A thicker boundary layer leads to a smaller diameter zone of laminar flow.

This smaller diameter laminar flow zone is moving at a higher velocity than would a larger diameter laminar flow zone.

Small droplet size from the injector is good but droplets do not all stay the same size. In regions where there is relatively less turbulence the drops tend to recombine to make larger droplets and in regions of relatively more turbulence the droplets tend to be smaller.

I used to have _The Two Stroke Tuner's Manual_ by Gordon Jennings and indeed I have found a complete copy online.

Image

http://edj.net/2stroke/jennings/

A long time ago a friend of mine made a 69 Camaro street machine with a 427 and a 6-71 GMC blower. When it came to heads he chose 396 passenger car heads rather than the L-88 427 heads he also had.

The reason for this is that he found after much research that even with a big blower, the smaller ports of the passenger car engine made for a higher midrange torque motor and midrange torque is what you want in a street machine.

This was a guy who had cut articles out of technical journals and car magazines for over a decade and had them indexed by subject.

"Tuning" an engine is really much like tuning a musical instrument, sound waves are used inside the engine in order to enhance the cylinder filling at particular rpms.

A port shape and length that fills the cylinder efficiently and effectively at high rpm will be less than optimum at lower rpm.

Take a look at this cutaway of a car engine and note the length and tapered shape of the intake ports.

Image


Top
 Profile  
 
 Post subject:
PostPosted: Thu Oct 04, 2007 6:21 pm 
Offline

Joined: Mon Sep 24, 2007 8:03 pm
Posts: 43
A couple more points:

Consider that a golf ball without dimples will only fly about two thirds as far as one with dimples.

Would dimpling the inside of the intake manifold make any difference?

Or does that only work for spheres?

http://www.fi.edu/wright/again/wings.avkids.com/wings.avkids.com/Book/Sports/instructor/golf-01.html

How good are the stock Suzuki heads, induction wise?

The only way to tell for sure would be to perform the experiment with a single head which you test stock and then modified both ways.


Top
 Profile  
 
 Post subject:
PostPosted: Fri Oct 05, 2007 7:08 am 
Offline
Bozo the crying clown

Joined: Tue Mar 13, 2007 9:19 am
Posts: 414
Location: Chester County PA
This is NOT intended to be a flame....

I'm gonna disagree on this one....

wanna know why? cause it's ain't so. heheheheheheh



Here's the REAL DEAL in "layman's terms"

On carbureted/tbi motors, you want the intake to be "rough".
On sequential port fuel injection, you want it to be as SMOOTH as possible.

Don't believe me? Then answer me this...Why does the Mustang crowd, and others , send their intakes to extrude hone incorporated to have their intakes smoothed out? I've seen the dyno numbers and felt the difference myself.


BUT....you ARE correct in applying that theory to CARBURETED engines.



Sorry dude...



Jimmy


Top
 Profile  
 
 Post subject:
PostPosted: Fri Oct 05, 2007 7:16 am 
Offline

Joined: Mon Sep 24, 2007 8:03 pm
Posts: 43
Carbureted engines also benefit from smooth intake ports.

If you are looking for maximum horsepower and torque at high rpm.

Porting and polishing have been around for a lot longer than fuel injection has been common.

I don't seem to be able to get it across that high rpm power and torque are not what you are looking for in an engine built for fuel economy.


Top
 Profile  
 
 Post subject:
PostPosted: Fri Oct 05, 2007 10:02 pm 
Offline

Joined: Fri Jun 03, 2005 4:36 pm
Posts: 493
Location: Roscommon, MI
Yes, but what they're saying is that a smooth surface will cause fuel to stick to it. A rough surface is better for an intake manifold that is flowing both air and fuel, to aid in the mixing of the two and hinder large drops from forming.

I certainly wouldn't, in any circumstance, polish a carbureted intake.


Top
 Profile  
 
 Post subject:
PostPosted: Sat Oct 06, 2007 12:02 am 
Offline

Joined: Mon Sep 24, 2007 8:03 pm
Posts: 43
rarson wrote:

I certainly wouldn't, in any circumstance, polish a carbureted intake.


Perhaps you wouldn't but hundreds of thousands have in the past.

The image below is of an Edelbrock Victor intake manifold for a four barrel carb. Note the porting and polishing that has been done on the intake runners.

Image


Top
 Profile  
 
 Post subject:
PostPosted: Sat Oct 06, 2007 8:06 pm 
Offline

Joined: Fri Jun 03, 2005 4:36 pm
Posts: 493
Location: Roscommon, MI
I'm not talking about porting, I'm talking about polishing. Those runners don't look polished to me.

Having a textured finish helps break up fuel droplets. On a carb manifold, this will help promote better air/fuel mixing.

It sounds to me like you're using the term "port and polish" generically, as if they always go together.


Top
 Profile  
 
 Post subject:
PostPosted: Sat Oct 06, 2007 9:27 pm 
Offline
Suzuki Elder
User avatar

Joined: Mon Dec 01, 2003 12:47 pm
Posts: 11669
Location: columbus, ohio
Soliton wrote:
When you roughen the intake port wall you thicken the boundary layer. A thicker boundary layer leads to a smaller diameter zone of laminar flow.

This smaller diameter laminar flow zone is moving at a higher velocity than would a larger diameter laminar flow zone.


that's a load of crap there, my friend.

impedance at the boundary layer decreases the velocity of every layer of laminant air right down to the center. increasing turbulence at the boundary layer affects every air molecule moving down the pipe, each molecule dragging down the speed of the next all the way to the center.

a decrease in the cross section of a tube results in an increase in flow only because it also decreases wall area which corresponds to the effective size of the boundary layer. smaller tube, less boundary effect, higher velocity.

maybe you have some magic pipes that provide synergy in the flow dynamic. :lol:

_________________
1991 Blue Geo Metro Convertible highly modified 1.0L Turbo3 5 spd. - 1991 Red Geo Metro Convertible customized with a Twincam 5 spd.

My Turbo3 Project
My Cardomain Page -Ol' Blue
My YouTube Channel
My Photo Gallery
SAAB Sonett II


Top
 Profile  
 
 Post subject: mileage/turbulation etc.
PostPosted: Sun Oct 07, 2007 2:21 am 
Offline

Joined: Sun Aug 20, 2006 11:31 pm
Posts: 57
Location: Lummi Island
[This smaller diameter laminar flow zone is moving at a higher velocity than would a larger diameter laminar flow zone.
[/quote]

Quote: that's a load of crap there, my friend.

"impedance at the boundary layer decreases the velocity of every layer of laminant air right down to the center."

Well actually that isn't always true, if the amount of vacuum is constant,
the outer diameter restriction and subsequent vortice can actually accelerate the center air mass substantially even without the vortice.
The prior comments about high RPM's and polishing are correct for the same reasons that high speed wings need to be very smooth and low speed wings are sometimes turbulated. This is why Reynolds numbers are used when referring to airflow, the reynolds numbers even the playing field so you can compare apples to apples with regard to flow dynamics.
All of our cars are operating at very low reynolds numbers, so turbulation will probably help economy and the proper turbulation could also help increase flow and HP.
Even if flow were restricted, the net gain from a better fuel air mixture would out weigh the insignificant loss in volume.

MM


Top
 Profile  
 
Display posts from previous:  Sort by  
Post new topic Reply to topic  [ 64 posts ]  Go to page 1, 2, 3  Next

All times are UTC - 5 hours


Who is online

Users browsing this forum: No registered users and 3 guests


You cannot post new topics in this forum
You cannot reply to topics in this forum
You cannot edit your posts in this forum
You cannot delete your posts in this forum
You cannot post attachments in this forum

Search for:
Jump to:  
Powered by phpBB® Forum Software © phpBB Group