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Discussion Starter · #1 ·
I highly recommend a little reading assignment for some of you guys.

Maximum Boost
by Corky Bell

He explains in detail how doubling the output power with forced induction only results in 20% more load in the most critical part of the power stroke. This is not speculation, all the formulas, etc are explained in detail. The added load is compressive in nature and not the most the most important aspect of engine design.

Inertial loads, which are not much of a factor if at all in adding FI to an NA engine, are critical aspects to consider when designing any piston engine. Over revving due to missed shifts or raising the rev limit are far more damaging than FI could ever be. As an example raising the rev limit from 6k to 7.2 k results in a 144% increase in inertial loads wether or not FI is added.

BAD tuning, over revving, improper heat management, poor maintenance, etc, kills far more FI engines than adding a reasonable amount of boost ever will.

Rick
 

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Tuning is crucial with any setup. So many people are so obsessed with power they will jsut shove ungodly amounts of fuel and boost in a enigner without proper tuning resulting in that wonderful kaboom noise. Thanks for sharing your find rick.
 

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I wasn't extremely impressed by that book. It was a good memoir and had some good pictures.

You can do math and figure out really how much force is on the engine components and use ESP to determine cylinder loading. Also, this motor has a longer stroke than most engines designed solely for forced induction. Also the valves are teeny. Also the ports are really flat.


Etc.
 

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The ports are flat and the intake manifold works a better than 90 degree turn. Sure the runners are pretty long and the curve is graceful, but geez, wouldn't it be a lot better to point the ports upward and run the manifold across the top instead of balled up behind the head? Oh well...

I can't comment on Corky's book, I haven't read it, but there are engineering limits to everything. Sure an over-rev does a lot more potential damage, but at the same time the materials the OEMs are using these days are a LOT better. It wasn't that long ago that 4000 fpm was considered the absolute limit for mean piston speed. Now they have better materials, and have done better analysis of piston movement and we have production engines running full service life with mean piston speeds well over 4500 fpm at red line.

Boost doesn't kill by itself, but I guarantee you boost and poor fuel are a death wish.
 

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Discussion Starter · #7 ·
mikey, scetchy in what way? You have made a rather less than enlightening statement with nothing of merit to warrant your point of view. Care to share your technical expertise as to why you feel the way you do?

Forged, At least you posted something tangable concerning the long stroke, cool. But, the rest of what you posted says nothing at all expect an opinion based on what? If you have reference material we can learn from then post it please.

Lance, Thanks for your imputs as well. The vast majority of tC owners are not looking to become engineers, rather they seek to find some level of performance that is reliable enough to be a daily driver with the least amount of headaches such mods can bring about.

I am searching all over the internet and have looked completely through the technical section of quite a large bookstore for more information with very little luck so far. They have alot of engineering books, thermal dynamics, etc, etc but nothing pertaining to the internal combustion engine with FI.

My goal is not to become some FI guru that knows it all(never met any know it alls that really did anyway) but to become more aware of what I as an individual can learn and apply to my own vehicles to achieve my goals and retain as much reliability as possible.


I also have no intentions of drastically modyfing the 2AZ to acheive some sort of massive power output, I just want a resonable amount that is actually usable instead of some dyno queen number that is not. So, within the design parameters of what we have to work with, my goal is to have a very streetable and reliable amount of power the limitations of FWD will allow me to expoit that power.

If anyone has usefull information, it would be great if you could share it;) I am just trying to clear the air as to what is or is not an area of concern when adding a moderate amount of performance to the 2AZ.

Rick
 

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Rick - my statement is based upon nothing, unfortunately. I mean, I dont know this Corky guy, but how do I know that he's even reputable? That's all.

I mean, I can say "You can gain alot if you just run Nitrous instead of 87-91 octane..." And if I say I'm reputable, some poor sap is going to do it, thinking that it's all safe. I mean, sure, I want my car to be a little faster, but I think there's plenty of evidence on this forum that it's not a great thing, unless it's done properly (tuning, etc) first.

Lance has made a great point all over this topic. Keep it legal, and safe, and warranted - go with s/c. Sure the s/c isnt going to give you the EXTREME power that a turbo would. But hey, if I wanted to spend the money taking an $18K car and putting $10 into it, I would've just bout a $28K car, that came with all the stuff that I wanted.

I'm not saying anything bad about you at all. Thanks for the info. I just think that it sound like one of those "too good to be true" statements...

Sorry if this is going to spark a huge fight. I'm done now.
 

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YOU HAVENT HEARD OF CORKY BELL!? WHER HAVE YOU BEEN!? j/k i only mildy remember him.
 

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If you want to learn something about engines,find a book by John Lumley called "Engines, an Introduction". By "Introduction" he means the same way a fluid dynamics book says "introduction". I'm writing [it will be my masters thesis] on HT and the complete combustion process in FI motors and he gives a great basis for concepts. Unfortunately, he does not go as mathematical that SAE papers do, but does provide a lot of good equations (though only a few are derived). I could give you a list of SAE papers 2 miles long that talk about any aspect you wish to discuss, in tremendous detail with thousand of diagrams pictures and experimental examples.

I try not to get too detailed on forums because I have nothing to prove, especially that i'm some e-badass know it all.


You have to realize that a turbocharger is just another machine. There's a scientific way to design for and around it and you won't find an enormous supply of books about it because it really isn't that complicated of an addition to an engineer. Honda has published a LOT of research on forced induction when they raced turbo F1. I've written some good stuff on valve flow and engine thermodynamics and I'm working on a really in-depth set of papers on both cam design and valve events. I'm having a great time drawing the diagrams for it.



I've read Maxmimum Boost several times, mostly when I was younger (as if i was old, heh) and knew less. It's not a bad starting point for a look into the actual goings on with the turbosystems but it in no way approaches the detail you would need to design something.

Lance, I was fabbing a manifold last night and was surprised at the angle of the exhaust ports, not to mention they aren't even symetrical! I'm hoping to get a spare motor in my shop and i'll throw it on the bench and do some porting and see where the best gains can be had. In all honesty it may be a good design for NA but FI calls for a different flow scheme (most notably because of the changes in mach number in the port at higher density.) What do you think about it.


I like the intake mani, but i'm sure i'll eventually make another one for a specific application.

Rick, I willPM you with a reading list.
 

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Originally posted by AcrimoniousBear@Feb 9 2006, 01:48 PM
YOU HAVENT HEARD OF CORKY BELL!? WHER HAVE YOU BEEN!? j/k i only mildy remember him.
Wasn't he the mentally retarded guy from "Life Goes On"?
 

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Originally posted by basilisk4+Feb 9 2006, 01:04 PM-->QUOTE (basilisk4 @ Feb 9 2006, 01:04 PM)
<!--QuoteBegin-AcrimoniousBear
@Feb 9 2006, 01:48 PM
YOU HAVENT HEARD OF CORKY BELL!? WHER HAVE YOU BEEN!? j/k i only mildy remember him.
Wasn't he the mentally retarded guy from "Life Goes On"? [/b]
HOLY CRAP, marty you made me laugh out loud during class!!! you bossturd, ok back on topic...sorry
 

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Originally posted by basilisk4+Feb 9 2006, 04:04 PM-->QUOTE (basilisk4 @ Feb 9 2006, 04:04 PM)
<!--QuoteBegin-AcrimoniousBear
@Feb 9 2006, 01:48 PM
YOU HAVENT HEARD OF CORKY BELL!? WHER HAVE YOU BEEN!? j/k i only mildy remember him.
Wasn't he the mentally retarded guy from "Life Goes On"? [/b]
Thats exactly what I was thinking but I couldn't remember the show name.
 

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god dammit, im still laughing!! i had to close the page during class to control outbursts thank you for giving me something to laugh at besides the sphincter punchers here at school
 

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whoooooaaa sphincter punchers....man thats horrible. by the way u guys made me laugh at home. can i join ur club now? HA!
 

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Originally posted by Forged@Feb 9 2006, 12:43 PM
Lance, I was fabbing a manifold last night and was surprised at the angle of the exhaust ports, not to mention they aren't even symetrical! I'm hoping to get a spare motor in my shop and i'll throw it on the bench and do some porting and see where the best gains can be had. In all honesty it may be a good design for NA but FI calls for a different flow scheme (most notably because of the changes in mach number in the port at higher density.) What do you think about it.
I'm guessing you've never seen a 2JZ-GTE head? Toyota has a history of making strange exhaust port configurations. The GTE heads on the Supras literally point to the center of the engine. The ports for 1 & 6 are more than 4cm longer than the ports for 2 & 5 or 3 & 4. I've assumed over the years that they did this for packaging to help get the exhaust flows merged as quickly as possible. On the GE (NA) head, the exhausts are nice and straight and all similar length.

I've ported them both for very large turbo applications, and I really think the GE head is a better choice. I was just disappointed that the owner of the GE head didn't want me to weld up the floors on the exhausts. IMHO, they are too big, and would be much better with a D shape and flat floor.

So, I look at this 2AZ head, and what do I see? The same kind of stuff I saw on the GTE head. Aiming the exhaust flow right from the valve seat towards an imaginary point in front of the head. Strange stuff, and no apparent reason for it, unless there's some packaging issue we don't quite understand. I really don't know why they are doing this, but I do know the Japanese have a very different way of looking at cylinder heads than US tuners do. Bike exhausts have historically been a lot smaller than what we like to see, but I haven't been in a bike engine for 7 or 8 years now. That may have changed.

There's also something strange with the angled squish area on the 2AZ. I don't know what they're up to with that unless they are expecting it to generate greater turbulence at the roof of the combustion chamber instead of the floor (the piston top). Then the question is, why, and what does it get them, and how do we optimize it for power since it appears to be for emissions control. Hmmm.

Any ideas?
 

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I've never stared at a GTE head before but I have been around some of built motors and did one or two turbo upgrades. I am used to staring at Mitsu heads and chevy heads for the past 2 yrs (last time I worked on a supra in that respect) so I can't recall. I've got an SAE paper collection and some case studies on the valve flow with toyota motors as the example ; i'll try to see if I can't reverse engineer their thinking. You are right, though, the japs take head flow different than most manufacturers, especially the germans, heh.

I've yet to see the inside of a 2AZ, and the minute I get one it's getting torn to the bare block for measurements. I don't have time to chat about chamber design right now but i've seen a lot of research on it and can make an educated guess at it later.

What kind of flow did you see on the 2JZ heads? I used a porting shop that claimed high 290s while keeping high velocity, around 28m/s. I think the guy from Head games sais low 290s at 28 was their goal on Ara's heads. I'm getting very similar results out of the 6G72 heads mildly ported, they have chunky ports by comparison but can still keep up a healthy flow velocity at higher rates.
 
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