Hello Group,
I was getting pretty bored reading about parts wants from the members.
So I decided to start a topic of real discussion.
OK... here goes.
I was reading on one of the honda sites.."like I said I was bored"
Anyway... Those guys are arguing about running HIGH compression on Turbocharged engines being a GOOD thing.....
I read all the posts and no-one ever mentioned that the engine being an AIR pump.
Mostly I just think they are WRONG!
The bigger the quench area the bigger the bang.!
Let me theroize for a minuet.
If you have a stock Pinto CR of about 8 to 1Â Vs. say 11 to 1 CR.
On the 8 to 1 engine you can put more air+fuel into the combustion chamber.
If you raise the CR to 11 to 1 then you get less air and fuel.
If you can cram say 11 to 1 CR into an 8 to 1 engine using a turbocharger @ 10 psi then you have more air and Fuel to expand Vs. the amount of area involved in turbocharging the 11 to 1 engine to 5psi.
If you can relate to this statement and have a view Please release me from my bordom and leave your coments.
From Pintony
Quote from: Pintony on January 25, 2006, 11:53:43 PM
...If you have a stock Pinto CR of about 8 to 1 Vs. say 11 to 1 CR.
On the 8 to 1 engine you can put more air+fuel into the combustion chamber.
If you raise the CR to 11 to 1 then you get less air and fuel.
If you can cram say 11 to 1 CR into an 8 to 1 engine using a turbocharger @ 10 psi then you have more air and Fuel to expand Vs. the amount of area involved in turbocharging the 11 to 1 engine to 5psi...
You are correct, sort of.
Yes, you do get more air in, but an engine will not change it's CR with a turbo or supercharger. The pushed in air will still be compressed in the same ratio, just at a higher pressure. Simply, the higher CR = more heat, thats all. That is why a higher CR works great with a N/A engine (to a point).
Pulling in air vs. pushing in air = night vs. day.
Bill
Hello Bill,
Thank you for your comment.
In your reply you mention AIR and I'll assume that you mean Air and Fuel.
Because an engine cylinder could be crammed with as much air as possible. BUT w/o fuel it does nothing.
Maybe I am wrong headed about this because I 'm "Old School" and running a carbed set-up on my Purple Pinto.
A turbocharged engine W/fuel injection is theoretically just air until the injector does it's job.
Let me see if I can clarify.
If an 8 to 1 engine can be boosted to a higher psi because it is a lower CR then there is not only more air there is more fuel. SAYING THAT THE A/F ratio is correct and the engine is not going lean because of improper fuel tuning.
I think Brad can shed some light here about a FI system having a lean condition. :angel:
From Pintony
Yes, fuel/air. I did not think I needed to get into the basics, but sorry for any confusion.
Keeping the "mix" correct is done better with EFI than with a carb (some will argue that). The "mix" needs to stay wiithin it's LEL and HEL to run an engine, but for the engine to run properly, make power and "survive", the mix needs to stay in a more narrow range (ratio) (the octaine of the fuel also comes into play). That's why (most) cars (and trucks) built today are efi. It helps with longevity (correct mix reduces engine wear), and emissions by using the least amout of fuel SAFELY to run the engine and make power at a given rpm and load.
When air (with or without fuel) is compressed, it gets hot (gives off heat). When compressed air is relased from, say an air tank, it will get cold (absorbs heat).
A N/A engine builds cylinder pressure (psi on compression) with the C/R. The higher the ratio, the higher the psi. A boosted engine builds it's "psi" during the compression of air(/fuel) that was forced into the clyinder AND the C/R, but the lower C/R reduces heat. To "turn up" the boost MORE safely, an I/C can be used to reduce more heat (more than one reason).
Introducing higher cylinder pressures (boost) to a engine that was made to be run N/A MIGHT be ok for a while (and fun to drive), but depending on boost applied and the engine itself, it can be very short lived. The failure I hear of the most is melted pistons (from heat I assume).
I also like when the use of I/C's on N/A engines is talked about.
Good topic Pintony.
Bill
Hello Bill,
Nice reply!
I really like the part about the Fuel/Air mix being held to a narrow margin to help the engine to survive.
That is something I have not thought about for a while.
Yes too much fuel and you wash the oil from the cylinder and too little fuel = melted pistons.
Very good point.
I really like your Thermal comments too.
I'm running 50/50 Alcohol water mix to cool my burn at max boost.
From Pintony
Hello Bill,
My WIS is controlled by a hobbs switch that is adjustable for boost
and activated by a solinoid. Just like NOS.
From Pintony
In answer to your why Q... Maybe everybody else has a job???? ;D ;D ;D
I'm out of work right now and READY to go back.
Monday is the day that i return to work.
I never thought I'd ever be happy about work!!!!! ::)
From Pintony
As far as my knowledge is concerned, C/R has no effect on air volume that actually gets in the cylinder. As far a efi is concerned, it's my opinion, that it doesn't necessarily 'mix' any better, but it just manages it better to keep the fuel/air ratio where it needs to be at varying conditions. That is why an efi motor will run much better at cold temps. than a carbed one does. Those rice eaters can run a higher c/r, but will not be able to use as much boost (p.s.i.), as with a lower c/r motor. No major difference, or gain, if you actually think about it. I think that more can be gained by using a different grind of cam in a turbo engine. Different opening and closing times and maybe a different centerline for more or less valve overlap. Just my thoughts --I'm definitely no expert.
Pintony, The more I thought about it after, I figured you might have it set up like nos. Kool. (Sorry for the pun).
34, I did not say efi "mixed" better, and COLD start-up is more of the issue with a carb. set-up (we don't need to tell pintony). As far as running, the colder the air the better for both. There is a BIG difference between a high c/r - low boost and low c/r - high boost. More boost works better than more cam to get more power out of a turbo/supercharged engine.
Bill
We could also run higher CR but remember the crappy, inefficient iron combustion chamber prevents it. Advantage ricer.
There is a good link in this link.
http://www.turboford.net/ubb/ultimatebb.php?ubb=get_topic;f=2;t=040335
Bill
for street use lower CR is better for turbocharged (or boosted or nitroused in gereral) as it allows better fuel economy and more importantly streetability with the use of pupm gas. MMFF magazine did an article on the same turbo kit put on identical engines with the eception of CR (one had 8.5 the other had 11.) The higher compression engine made alot more horsepower with the same amount of boost but it also required higher octane gas at a lower boost level than the 8.5:1 motor. EFI gets better atomization of the fuel Sent into chamber under pressure) than a carb, therefore they are more efficient.
Quote from: 77turbopinto on January 26, 2006, 06:05:54 PM
Pintony, The more I thought about it after, I figured you might have it set up like nos. Kool. (Sorry for the pun).
34, I did not say efi "mixed" better, and COLD start-up is more of the issue with a carb. set-up (we don't need to tell pintony). As far as running, the colder the air the better for both. There is a BIG difference between a high c/r - low boost and low c/r - high boost. More boost works better than more cam to get more power out of a turbo/supercharged engine.
Bill
OK fast34,
You introduced a NEW factor in to the equasion of this discussion.
CAM!!!
If you have say, a BIG cam and do not increase your CR then you have in effect lowered the CR because of "overlap".
Then the discussion takes on a different aspect to the original discussion because...
IF efectivly lowering the CR by use of a BIG cam "FOR ALL OUT POWER" Then Yes I can see where the CR of 11 to 1 may be nessissary to achieve MAX HP.
This discussion if falling into the crack where I say "You can not talk to a RACER about your street driven engine because they are only interested in MAX HP."
NO other factors are present.
The racer is not concerned with Milage, Driveability, off idle acceleration, JUST MAX HP!
I have concluded that the Original topic of high compression turbocharging is a RACER thing NOT a street driven modification.
I welcome the members here their continued points of view on this subject.
I'm thinking Maybe a little more CR to help out low end driveability might be a good thing.
The original 2.0 comustion chambers that I have cc'd are about 46cc. The Combustion chambers on m y Purple Pinto are 51cc due to the combustion chamber modifications I have performed. My chambers are Morror smooth & all sharp edges have been broke using a jewlers file. + stainless valves
Hopefully my C.C. hot spots are now to a minimum.
If I pull the head someday I MAY have a few thousands removed to raise the CR a bit. But most likely since I keep good notes I can just introduce these modifications into the next 2.0 turbo engine I build.
From Pintony
I also want to give 78 Pinto credit for pointing out the Street Vs. Race aspect.
I sometimes forget about that when I read something which I do not nessissarly agree.
From Pintony
Hey Pintony,
Much thanx for the rescue from the freezing winter doldrums ! ! !
The grey matter upstairs dwindles with age, especialy at this time of year.
Being wrapped up with projects for the spring car shows leaves not a lot much more to consider than keeping warm while swinging the wrench, looking for some reason to keep from getting one's head examined ! ! ! :o
Not knowing my anus from my nostrils about turbos, (have a drive train fron an 87 Cougar Turbo EFI X-R7), I shall remain glued to your post. I wish tp place said unit into a 71 Sedan someday.
I will go out on a limb here, but I ask that you consider the air pump theory.
Rather pushed or pulled, the ultimate scenario culminates when the mixture is detonated, in a given area, with a given piston compisite material, and a compatiable array of elements that will achieve the most desired means to the end of the perputal motion therory. and the combustions results being expediantely removed from the scene of the crime!(for cooling pourposes).
Having said that, I would think that the mass, (air/fuel, and what ever gas, plural), that enters the chamber, would be revelent
As we all know, water can not be compressed, however it plays a big part in the combustion process, (atmospheric humidity).
Not running for President on this one, but thanx to Pintony for the splash in the face!
Al
in CT.
One thing to keep in mind here also.
Boost is just a measure of how much restriction there is in the intake path... not a measure of power potential or air flow.
The modern engines are generally aluminum headed and have MUCH more efficiant combustion chambers.
Modern engines generally have much better intake tract flow.
You want the smallest quench area for a given compression ratio, if possible have the dish in the piston directly under the quench area of the head. This lowers the posibilty of detonation.
Most high compression engines that are running boost are running a lower level of boost than the low compression guys.
Off boost these cars will have a lot more snap to them, and on boost they still pull nice and hard.
Best rule of thumb when building a turbo car... and I KNOW a lot of people disagree with this... is to build a strong NA car, then boost it. Only dont get carried away on overlap.
On the overlap topic, I have seen a few dyno runs with cars that have "wrong" cams for turbos. It is amazing how well they work.
"If you have overlap you will be pushing the mixture out the exhaust valve!!!" Anyone care to time how long both valves are hanging open from 3000-7000 rpm and how far they are both open? ;)
I have had dealings with turbo LS1 GMs, turbo 5.0s, turbo 4.6s, turbo hondas, and all kinds or other turbo vehicles since I got into playing with turbos in 91...
Most of the "you cant do that" things are opinions... and are blown out of the water when people say screw convention... and play outside the box.
Jim
Pintony, I did not bring up the cam thing, 34 did, i just replied.
Bill
Hello Group,
I have corrected my error.
Thanks bill.
This subject line is going better than expected!!!!!!!
I love reading how other members minds work and the other perspectives on this topic!
Special thank you to FOMOGO for his opinion.
FOMOGO has added yet another valued perspective.
From Pintony
Jim is right, the more power a car makes N/A the more power it will make with boost.....but there is the "what fuel will you be using" question that pops up. For a street car i would try to keep the CR to under 9:1 max, but i have seen them at 10 (with points) :1 but i think they are running the edge with that. They may only run 4-5lbs of boost on the street with 93 pump gas, but with a tank of C16 at the track and a few twists of the dial a boost.....look out! Boost is a fucntion of restriction that is very true, two identical engines one with AFR 205 heads and the other with say factory ported heads will be way different in there boost capacities. The AFR headed car we'll say makes 600hp at 14lbs of boost and the stock headed car would need say 19lbs of boost to hit that same power level (same thing is true with the intake tract) By the way Jim, have you got your car boosted yet?
This is what "bench racing" is all about. We get to exchange ideas, and with it online, I won't wind-up getting a fat lip.
Sometimes, for me, I will state an opinon based on certian facts, and not fully explain the perameters.
Bill
Quote from: 78pinto on January 28, 2006, 09:46:50 AMBy the way Jim, have you got your car boosted yet?
Not yet... this thing called unemployment reared its ugly head and forced the sale of a LOT of stuff.
I am working again and will soon start gathering parts again tho. :D
Jim
Am wondering, after my attempts to understand all of the info presented in this post, how to plan for a EFI turbo power plant.
I think that I've heard of a Ford turbo web site somewhere. Any suggestions for books or manuals regarding componets selection, (pistons, cams, valves, headporting, etc?), that would help the novice. I have a drive train with all of the wiring plus the "eek" box? It's the one that was tucked into the front passenger kick panel that seems to control just about all of the engines functions.
It seems as though Racer Walsh had a rebuilt turbo unit available as long as you had a core to swap for it, headers for the unit also. Am not sure if it's still available. Are there any other suppliers out there, besides Esslinger?
I suppose it's never too early to start planning.
Al
in Ct.
www.turboford.org
Go there... type your questions into the search engine.
YEARS worth of archived tech info for you to browse there.
General turbo related books.
Maximum boost by corkey bell
Turbochargers by hugh McInnes.
Shop around for turbochargers, the holset HY35W from a dodge cummins is a popular one for guys wanting good power right now.
Depending on what year your engine is, you may be able to upgrade to a stock turbo from another year 2.3
Esslinger, Racer Walsh, and many vendors on turboford can help you with parts aquisition.
Jim