Interresting tuning articles

[klatinn]

Hi,

Here are some interresting tuning articles on other web-sites that have been posted here before. I'm making this a sticky so it's easier to find:

http://www.avweb.com/news/columns/182084-1.html

http://www.avweb.com/news/columns/182085-1.html

http://www.avweb.com/news/columns/182132-1.html

http://www.streetrodstuff.com/Articles/Engine/Detonation/

Happy reading.

[Sidewinder]

Some other online tuning magazines:

http://www.tuningmag.net/ - articles from the world of tuning, the nicest webpage full of great photogalleries, forum
http://www.tuningnews.net - many articles from tuning world, forum
http://www.tuninglinx.com - daily updated content, many articles, but a little short.

[xr3tf]

I have tried to access the old articles, but they are no longer available. Would someone perhaps be able to e-mail it to me if still available - it will be much appreciated.

[john,???]

yeah, i was looking for them too

[Tuner]

These links are courtesy of Mr.Mark Andereck

Originally Posted by Andereck

Okay, fair enough. If you have an open mind and patience read the following on tuning aircraft engines and think about how that applies to tuning race cars.

http://www.gami.com/articles/bttfpart1.php

http://www.gami.com/articles/bttfpart2.php #5 midway down discusses the relationship of stoich to peak egt

http://www.gami.com/articles/bttfpart3.php more of the same with a bit of a sales pitch on balanced fuel injectors

All of these concepts apply to what we're doing. Peak egt occurs at stoich. Temperatures fall off due to either excess air or fuel. Being on the slightly rich side of stoich can be more dangerous than slightly leaner.

[klatinn]

Some more interresting info about plug wires:

http://www.magnecor.com/magnecor1/truth.htm

And another fairly well written one (albeit with some small detail errors) on ignition timing:

http://www.max-boost.co.uk/max-boost...ion_deeper.htm

[LC1 Freshman]

The following is a good read for turbo applications
http://innovatemotorsports.com/resources/rich.php

[john,???]

this was pretty good for me...


http://www.castensdynojet.com/insiders.htm


I didn't know a lot of that stuff.

[LC1 Freshman]

Even though it's a patent for old school ECM technology, there is some good tested info on ignition characteristics of alcohol fuels (basically fig 3 and 4, thats it).

http://www.google.com/patents/pdf/Sp...J3vPgUK3s1wkYY


Despite the thick, "Holy-Handgrenade" like mix of fragmented bits of info, it does point out that alcohol propagation slows in respect to pressure but is relatively faster compared to gasoline. So advance is needed at peak load, but as rpm climbs less timing is needed (compared to gas).



Below is a MUST read for those interested in gaining cutting edge knowledge on the topic of turbocharged alcohol combustion. Valuable indeed
http://www.orbeng.com.au/orbital/tp/...07-01-3625.pdf

[bestforcar]

All information about new cars and tuning cars. Tuning components, pictures and news. You can find information about tuning cars, styling and performance tuning.
http://www.4tuning.110mb.com/

[neither]

At http://www.thefamost.com you can show your amazingly tuned car to the whole world and much more

[Arent]

I found this great Dutch/Belgian site, It's http://www.tuning-gids.nl.

Loads of tuning tips and much more. Only drawback is that it's in Dutch
language. But the pictures explain a lot!

Have fun.

Arent

[LC1 Freshman]

Didn't find the above article useful, even after mild translating. I don't know Dutch. My wife speaks Dutch, but she doesn't tune fast car's.

I heard Germans and Dutch often are at odds with each other, true?


I would like to see some information relating to an in depth (not too in depth, like MIT) study relating to the effects of various cam set combinations of fixed valve timing on a DOHC, port fuel-injected, small-medium sized twin-scroll turbocharged, 4cyl pent-roof application with a moderate compression ratio and is not knock limited but highly boosted.

That would be what my interests are, any links?

[LC1 Freshman]

I'm compiling a list of favorite quotes to this thread.

Here's the first:

Intro to Combustiochem 100

Originally Posted by klatinn

That requires a somewhat more complicated answer. It's not as simple as lean burns slower and rich faster. Solely depending on AFR, the flame kernel growth (flame-front onset delay) is shortest at around 11.5 to 13.5 AFR. Longer the more you get outside that range. The best ignition timing is achieved when the point of peak pressure (ppp) in the cylinder is at it's optimum point. This ppp is somewhere at around 7-18deg ATDC, depending on engine geometry, but NOT dependent on load or RPM. A slower burn requires more ign. advance to hit the optimum ppp. But any pressure buildup from the burn BTDC tries to turn the engine backward (negative torque) and therefore costs torque (and hp) overall. Also, at the optimum ppp about 50% of the mixture has burned. Still burning mixture at late crank angles do not contribute much to the torque as the piston can (at high rpm) outrun the pressure buildup. The high temps at around stoich mixture come from the complete conversion of carbon to CO2, which releases the most heat energy. The mixture stops burning if either all oxygen is used up or all fuel is used up. Richer than stoich means that the oxygen runs out first, leaving carbon only partially burned to CO (resulting in lower EGTs and CHTs compared to stoich). Leaner than stoich means that the fuel runs out first and the excess O2 dilutes the resulting gas to lower temperatures as well.
In an ideal (Carnot cycle) engine all the energy is released at once shortly after TDC. That is not practical because the resulting pressure peaks would quickly destroy the engine.

Regards,
Klaus

Good one for starters

[LC1 Freshman]

Another:

Originally Posted by klatinn

Hi,

Two things:

Re: Dynamic compression
With "dynamic compression" I mean what Schrinker said (actual compression), but ALSO the effects of throttling. The efficiency increase of an engine from higher compression is not actually coming from the increase of compression ratio itself, but from the increase in expansion ratio. As the burn is completed the high pressure gas gets expanded by the piston moving down until the exh. valve opens. The ratio between max pressure and pressure at exh. valve opening is the expansion ratio, that is among other things, determined by the compression ratio. If you throttle to for example 1/3 atmospheric pressure in the intake, the piston basically has to compress a 2/3 vacuum. That then (in the absence of combustion) gets expanded to close to atmospheric pressure. With combustion you just basically multiply the pressure with the heat rise from combustion. But you start out with a lower value before the multiplication.
That's why the lower efficiency when throttling. This is also the reason efficiency goes down (together with milage) when using a restrictive exhaust system. Late intake valve closing basically makes the effective compression stroke shorter than the expansion stroke. If you make up the compression loss from late IV closing with (intercooled) boost, you increase efficiency. This is basically the idea behind the Miller Cycle engine.

Re: Water injection
It has severall effects. Among other things it also depends WHERE you inject the water. If you inject pre-turbo, the water will be finely atomized enough that it turned into steam by the time it gets into the engine. In that case it basically acts as dilutant like EGR. Different to EGR though, it lowers intake temps because of its high latent heat, increasing intake gas density, and thereby to some extent, counteract the dilution effects. Anything that lowers intake temps will decrease the knock likelyhood.
If injected close to the intake valves, it will enter the cylinder in droplet form. It will then turn to steam during compession from the heat created by compressing the mixture. This lowers the compression induced heat rise, which has a significant anti-knock effect. Also increases efficency because less heat rise means less compression work has to be performed by the engine. The pressure rise from the water turning into steam is not significant as typically the amount of steam is very low compared to the total gas volume processed by the engine.
A secondary effect is the promotion of faster and better carbon combustion. Water radicals are needed for the CO to CO2 conversion. Water radicals form in the flame-front from the combustion of the hydrogen part of HC fuels. The temperatures in the flame front are high enough to split the water molecules into radicals. Faster combustion ALSO means higher efficiency as that also increases the total effective expansion ratio.
Again, alcohol fuels (especially methanol) have the edge there because their laminar flame front speeds are higher than gasoline. Though their initial flame kernel delay is longer. Which means the ign. timing does normally not change much and they have typically more scatter in the peak pressure point.

- Klaus