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Old November 1st, 2001, 11:47 AM   #26
hyc GTS
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to FE3T - of course, there's no reason to go overboard in lowering CR just to raise boost. As many other posts have already stated, you want a reasonably high CR for off-boost driveability...
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Old November 1st, 2001, 11:26 PM   #27
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Quote:
On Thursday November 1, 2001 6:39 PM, hyc GTS wrote:
(fyi, the formula for thermal efficiency comes from page 407 of my 4th Edition Bosch handbook.)
Harumph... I can't find it in my 5th edition.


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On Thursday November 1, 2001 4:19 PM, BryanPendleton wrote:
Quote:
On Thursday November 1, 2001 3:57 PM, ASword wrote:
Power comes from more air, and more air comes from displacement and/or boost.
That sums this hole topic up the best. I love it. . . short and sweet.
We aim to please. Verbal efficiency. :smile:

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Old November 2nd, 2001, 10:11 AM   #28
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Great String, thanks for the info/equations. I knew anecdotally that the lower CR/higher boost was correct, but haven't seen the equations before.

Anyone know how lower CR will affect emissions. (I'll be running 8.5:1; finally received my new Eagle rods and Ross pistons on Wed.)
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Old November 2nd, 2001, 10:24 AM   #29
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On Friday November 2, 2001 12:11 PM, Joe Kamman wrote:
Great String, thanks for the info/equations. I knew anecdotally that the lower CR/higher boost was correct, but haven't seen the equations before.

Anyone know how lower CR will affect emissions. (I'll be running 8.5:1; finally received my new Eagle rods and Ross pistons on Wed.)
Lower compression will help your NOx emissions. Since you're going to a stand alone [or however the TEC II is classed] I don't think you'll have any problems passing emissions. Tuning! :smile:


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Old November 2nd, 2001, 04:25 PM   #30
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That's good news. I recently realized when I made the decision to lower the CR a little, I hadn't thought about passing the local testing (my post above is wrong, I'll actually be at 8.8:1).

Since the shop that is doing the rebuilding didn't want to mess with the TEC II, I've had to set up the engine to run off the factory computer. I had set up everything to run in parallel, so it was quite simple. About all I've had to do is bolt back on the OEM injectors/rails, and put the factory airbox, and VAF back on. So, my backup plan for passing emissions, hopefully it won't be an issue with the TEC II properly tuned, would be to set it back up to run on the factory computer to pass the test.
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Old November 19th, 2001, 06:04 PM   #31
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I corrected this post based on Howard's note 2 posts below (that the OEM is 2497cc, not the 2449 that I orig had in the post), and another miscalc that I found (my .100 over bore is actually 2646cc, not 2665).
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Sorry, I’m going to sound a bit naïve here, but bear with me. Let me see if I understand this string correctly. It seems like we started with the same dynamic compression ratio. Is this because dynamic CR relates to detonation, and we want to compare the HP that the two engines will make at the same pain threshold level?? Or was there another reason that we compared the two engines starting with the same dynamic CR?

Anyway, from Howard’s info I get that HP is directly proportional to 1) thermal efficiency and 2) volume of air, all other things being the same. And, I’m also assuming that torque, and thus HP, is directly proportional to cubic inches of displacement.

If this is all correct, then this should be the math for my engine (2646cc, 8.8:1CR) as compared to a KL03 with 2497 cc, and 9.2:1 CR.

Thermal Efficiency factor: ==> 53.3/54 = .987

Volume of Air Factor ==> 9.2/8.8 = 1.04545

Cubic inch Factor ==> 2646/2497 = 1.05978

So, the HP of my 2646 cc, 8.8 CR will be: .987 x 1.04545 x 1.05978 times that of the KL03.

Or, my build will put out 1.094 times the HP that the KL03 will put out, if they both are run at the same dynamic CR. Or, for a 250 HP build KL03, my build will put out an additional 23.5 HP.

Note that most of the extra HP, roughly 2/3 comes from the increase in cc’s, and the reduced CR only nets roughly 1/3 of the gain. Is there another benefit from the lower compression that doesn’t show up here, or is the gain that slight?

Let me know if I’ve done any of this wrong

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Old November 19th, 2001, 06:48 PM   #32
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Quote:
Staying on the theoretical side: how could you create two engines that were completely identical *except* for their static CR? Does that mean they have the same bore & stroke, but different piston shape?
You can't. But you can have the same bore and stroke - you'll just have to use a different piston in the lower compression engine. That means a larger combustion chamber volume (at the top of the cylinder, not in the head), but the swept volume is the same.

Quote:
Assuming you have an answer to that question, then clearly the higher boost engine will produce more power at a fixed dynamic CR, because it ingests more air mass than the other.
*IF* the air/fuel density ratio is the same in both engines, the lower compression engine *WILL* have more air and fuel than the higher compression engine, since the the combustion chamber is larger on the lower compression engine.

Howard's hit the nail on the head - there's the reason the low compression + boost engine gives you more power. More combustion volume lets you burn more fuel. The "dynamic" compression ratio allows you to assume similar air/fuel density in the combustion chamber.
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Old November 22nd, 2001, 05:10 AM   #33
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Mebbe someone should distill this topic into the FAQ...

Joe: yes, we're comparing two engines at "the same pain threshold" as you put it.
It's not actually clear to me that this is really the same knock limit in both cases, because the engine with higher boost will have a hotter intake charge, but I guess we'll let that slide since the cylinder pressures prior to ignition will be the same.

By the way, the stock KL03 displacement is 2497cc not 2449 so your cubic inch factor is 1.0673, not 1.08819. I get 1.1013 as a final result, 10% improvement over stock. I think otherwise the numbers are reasonable. There are no magic bullets, you can't tweak one little thing and expect dramatic improvements.
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Old November 22nd, 2001, 12:18 PM   #34
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On low compression/high boost street cars:
There's a MKIV running 6.9:1 compression and 40psi on his 2JZ. On stock turbos, he hit 128mph traps. It's apparently a dog on the street, but on the boost it makes 900bhp.

Then there was Jay B's first gen, running 24psi on a 9.5:1 motor, for 500+whp. The joys of stand alone engine management. :grin:
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Old August 9th, 2002, 07:07 PM   #35
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I enjoy this topic, and have more to add to it:
This was written by a Honda guy, but the theories cross over
Quote:
There has been a long-standing myth with turbocharged Honda cars. For as long as I can remember, people have been quite concerned about having too high of a compression ratio, on their turbocharged Honda. The myth is: the lower the compression...the better. Well, this is not entirely true.

Why is a low compression motor good to turbocharge?

In essence, a low compression motor is good to turbocharge, because it is just easier to do so...and not worry about it. But is that what we really want to do as enthusiasts? Do we want to just slap a turbocharger on a car, and call it a day? Absolutely not. With turbocharging, comes the responsibility of tuning and care. If you are just going to turbocharge your car, and call it a day, then frankly, you don't deserve the luxery of boost! As well, might I add...that simply because it is easy to slap a turbocharger on a low compression motor and not worry about it, does not mean that it is right. I can guarantee you, that if you turbocharge a low compression motor, and fail to tune it correctly, you will end up on the side of the road, with blue smoke coming from your exhaust pipe.

Generally, a lower compression motor affords you more margin of error, when tuning. A slightly imperfect a:f ratio probably won't lead to the demise of your motor...unless you drive like a total jerk.

Why should I consider a higher compression motor, while making my decision of what motor will suit my needs?

Different from a low compression motor, a higher compression motor will not give you a large margin of error, when tuning. As stated before, if you expect to slap on a turbocharger, and call it a day, well then stay away from the higher compression motors all together. A higher compression motor demands slightly more TLC than a lower compression motor. But oh, the rewards are plenty.

Bottom line...a higher compression motor, pound for pound, will make more power, than a low compression motor. This works along the same lines as naturally aspirated Honda motors. You never see an NA enthusiasts spouting off about low compression do you? No, one of the keys to NA performance is high compression. So, why should it be any differnt for turbocharged applications? Of course, the routes to high compression are different (NA uses lightweight rods and pistons, that a turbocharged application would simply tear to shreds), but the end goal is the same.

Let's make an observation here. I am going to throw a scenerio for you...

Car A:
B18B (stock 9.2:1 CR)
Rev Hard Stage II
Thermal 3" exhaust
MSD 6AL
MSD Pro Cap
MSD Blaster 3 Coil
Holley 255lph in-tank fuel pump
AEM fuel rail
RC440cc injectors
A'pex S-AFC

Car B:
B18B (JE pistons, 10.5:1 CR)
Rev Hard Stage II
Thermal 3" exhaust
MSD 6AL
MSD Pro Cap
MSD Blaster 3 Coil
Holley 255lph in-tank fuel pump
AEM fuel rail
RC440cc injectors
A'pex S-AFC

Now for the sake of argument, let's say that both cars are well tuned, by the same tuner, both have an identical weight, both have the same slicks, both are boosting 1.0bar, and both are being driven by the same guy...at the same time (yeah, yeah, yeah...just roll with me here)! Now, which one do you think is going to come across the finish line first? Mythological thinking says that the guy with the low compression is best suited to win...right? Wrong. The guy with the 10.5:1 compression ratio is going to smoke the guy with the low compression.

Another point I would like to bring up is the misuse of the term "high compression" when it comes to Honda motors, and turbocharging them. In all honesty...10.6:1, 11.0:1, etc...aren't even really that high. Most NA monsters utilize 12.5:1 or higher...and some even as high as 14.0:1, in cases of extreme race. If you do some snooping around, you will realize that most of the really fast Hondas, and I'm talking sub-10 second monsters, utilize high compression setups, to achieve enourmous horsepower goals. Most of these guys won't openly discuss it though, so you are likely to come across terms such as "undisclosed compression", or something along that line. As I stated before, the myth is that low compression is key...so these guys want to stay on top, and the way to do it is hide the fact that they are using high compression, turbocharged motors...to propel themselves into sub-10's.
[cont]
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Old August 9th, 2002, 07:08 PM   #36
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cont...

Quote:


Reliability, and compression...

This is a regular question that pops up, and is quite valid. Frankly, as soon as you modify a Honda at all...reliability becomes an issue. A lot of us can testify that the proverbial "can of worms" sprung open as soon as we made our first modification. Many times, Honda enthusiasts will spout off the reliability factor, in Import vs. Domestic wars, when in actuality, they fail to realize that we are in just as much danger as those old pushrod V8's are, as soon as we modify our Honda engines.

Now, what is the solution? I have been saying it for a long time, as have several others such as Tuan, neouser, texan, and st00pid...TUNING IS KEY! That's the bottom line.

A well tuned higher compression motor will last just as long as any low compression motor. Tuning is not a factor that can afford to be sacraficed. You will not survive with an untuned higher compression motor, just as you will not survive with an untuned low compression motor.

So, with all of that said, it basically boils down to your own personal choice. Do not fear the B16A, the B18C1, or the H22A...etc. If you have the monitary requirement to turbocharge a higher compression VTEC motor, I would say, do not hesitate to do so.

I hope that you have a slightly better understanding of how compression and turbochargers co-exist. If you have any questions, feel free to make a new thread, and inquire. Thanks for reading!
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Old August 9th, 2002, 07:08 PM   #37
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more I found...
Quote:
One main concern in power production with forced induction is effective compression. Effective compression is the sum of the motors static compression, plus the additional compression added by the forced induction tool. A B18C1 (also B16A) motor will have a higher effective compression than a B18B motor will, on the same boost...therefore, pound for pound, it will make more power.
The next argument that people usually bring up is that a higher compression is bad for turbocharging. Well, if you understand the concept of effective compression, then you should understand that this statement is entirely incorrect. A higher compression engine makes more power in NA form. So, why do you turbo guys think that a lower compression turbo motor makes more power? Does that make any sense when you really think about it? A turbocharger is a power adder? So why deplete power that was there to begin with? The answer I usually get to that is "So I can run more boost!" Well, sorry to rain on your parade, but more boost does not always equal more power. Check out this mathematical example of effective compression:

A motor with a 10.0:1 static CR boosting 10psi
10psi/14.7psi = .68
.68 + 1 = 1.68
1.68 x 10 = 16.8 effective CR

A motor with an 8.5:1 static CR boosting 10psi
10psi/14.7psi = .68
.68 + 1 = 1.68
1.68 x 8.5 = 14.28 effective CR

Now tell me who is going to make more power? The higher CR motor, or the lower CR motor?

So, maybe add more boost to the lower CR motor, right? Wrong...

A motor with an 8.5:1 static CR boosting 13psi
13psi/14.7psi = .88
.88 + 1 = 1.88
1.88 x 8.5 = 15.98 effective CR

Now you see, even adding 3psi of boost, still does not equal the effective CR of the higher compression, lower boost motor.

Effective compression is not the only advantage of the B16A/B18C1 either. The B16A/B18C1 has a stronger, better flowing cylinder head. It can rev much higher, making it that much more effective, and it flows great to handle all of the extra volume. The block has oil squirters to help support the bottom end assembly at high RPM. It takes more than a valvetrain upgrade to make a B18B safe at 8k. The higher compression also aids in spooling the turbo faster too.

Both motors have similar tolerances though. Both motors pretty much top out at around 350-400hp on stock motors, very well tuned. The B18C1 will make it far more efficiently for you though. It takes less boost to do so, it has more safeguards...and the bottom line on any Honda motor is tuning. If it is well tuned, you will be set. That goes for both motors. YOU ARE A FOOL if you think for one second that just because your B18B has a lower compression, you can substitute that for proper tuning.

A lot of people like to lower their motors compression when they build their motor. I used to think it was a good idea before I understood about tuning, and the positive aspects of compression. In the mathematical representation below, I will show you how a low compression motor must boost more to equal the output of a higher compression, lower boost motor:

Motor: stock B16A2 boosting 7psi.
Static Compression Ratio: 10.4:1

((boost psi / 14.7) + 1) x motor compression = effective compression

Stock motor (10.4:1 CR) on 7psi:
7psi/14.7psi = .47
.47 + 1 = 1.47
1.47 x 10.4 = 15.288 effective CR

Built motor (9.0:1 CR) on 7psi:
7psi/14.7psi = .47
.47 + 1 = 1.47
1.47 x 9 = 13.23 effective CR

You will lose 2.058 points from your effective compression ratio, this translates to a significant power loss.

In order to gain back that power, you have to do this:

Built motor (9.0:1 CR) on 10.5psi:
10.5psi/14.7psi = .71
.71 + 1 = 1.71
1.71 x 9 = 15.39 effective CR

Add 3.5psi to what you were boosting before, and you should be able to make around the same power as before, granted you haven't done any other kinds of modifications port/polish, cams, etc...

As you can see, considering all things stay equal (bore/stroke/cylinder head/etc...), you must add 3.5psi to make the motors perform similarly. You just spent about $2,500 to build your bottom end, and make your car slow.

By now we all should understand the positive aspects of compression, and how when teamed with the faster spoolng turbo, more efficient output, better flowing B-series VTEC cylinder heads, better low end spool time, stock oil squirters, higher redline, etc...you should see that turbocharging B-series VTEC motors is clearly not dangerous, and highly adviseable. I love a good turbo B16A!
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Old August 9th, 2002, 08:30 PM   #38
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I don't like the "effective compression" math that is being tossed around in that last message. Increasing an engine's compression ratio doesn't increase and amount of air inducted (and therefore the amount of fuel injected), unlike running boost. High compression extracts energy more efficiently from whatever mixture you managed to get into the cylinder, so you can't really combine them into one number like that and compare the result.

The above messages also seem to ignore the problems with hitting the auto-detonation limit of gasoline. Running boost on a higher compression engine will start experiencing this form of detonation at a lower boost level than a lower compression engine. If you're using race gas this is less of an issue, but with pump gas on the street it is an important factor. Intercooling helps... but it helps the lower compression engine more.

That said, however, these guys do have a point that you don't necessarily want to modify your engine to make a huge drop in CR -- it will likely not pay off. The flipside is also true, however, if you are going to boost a lower compression engine (i.e. KLD) it probably isn't worth going through the effort and expensive of upgrading to a higher compression one first (i.e. KLZE) unless there are ulterior motives (i.e. its a much newer / lower mileage engine).
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Old August 10th, 2002, 05:11 PM   #39
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Quote:
Originally posted by ASword
I don't like the "effective compression" math that is being tossed around in that last message. Increasing an engine's compression ratio doesn't increase and amount of air inducted (and therefore the amount of fuel injected), unlike running boost. High compression extracts energy more efficiently from whatever mixture you managed to get into the cylinder, so you can't really combine them into one number like that and compare the result.

The above messages also seem to ignore the problems with hitting the auto-detonation limit of gasoline. Running boost on a higher compression engine will start experiencing this form of detonation at a lower boost level than a lower compression engine. If you're using race gas this is less of an issue, but with pump gas on the street it is an important factor. Intercooling helps... but it helps the lower compression engine more.

That said, however, these guys do have a point that you don't necessarily want to modify your engine to make a huge drop in CR -- it will likely not pay off. The flipside is also true, however, if you are going to boost a lower compression engine (i.e. KLD) it probably isn't worth going through the effort and expensive of upgrading to a higher compression one first (i.e. KLZE) unless there are ulterior motives (i.e. its a much newer / lower mileage engine).
I agree that more air means more power [mostly], but higher compression is going to have nice benefits like quicker spool, better off boost response, and better MPG [due to more effeciency and lower boost level]. I went with a KLZE cause I had to swap to a 2.5L anyways, so why not spring the extra 200 bucks and get better flowing heads, cams, and higher compression? As you well know, we're limited by fuel for 95% of all the boosted KL's [~5-9psi, depending on compressor], so unless you want to lay down some serious coin on controlling bigger injectors [either custom EPROM like your crazy project or a stand alone like the sane KL boosted guys do ], you'll make more power with a boosted KLZE as pressure level is pretty muchly fixed for the above mentioned reasons. I guess I have a unique view on the whole boosting a KLDE vs a KLZE, cause I had neither motor to start out with, but my teeny K8 [you should see the rods...they're ridiculously long] 1.8L.

RE: Preigntion...Looking at the quench area on our heads versus B series honda stuff as well as the head surface area, it sure seems that if our heads are kept at an equal temperature, we will have less detonation prone heads than the Honda B series VTEC stuff. Of course, who's gotten preignition on a KL yet? Chad was pushing 14psi on pump gas on 9.2:1 CR w/o knocking....which is the same effective compression [which links to preignition] as a KLZE @ ~11psi.


Just things to ponder next time somebody posts the rhetoric about "ZE's can only take 5psi y0!"
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Old August 10th, 2002, 07:42 PM   #40
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Quote:
Originally posted by David Coleman
Just things to ponder next time somebody posts the rhetoric about "ZE's can only take 5psi y0!"
No argument from me on any of that.

A KLZE can only take you to 5 psi in a non-intercooled setup, but a KLD will only take you to about 8 psi. Chad is intercooled. The wonders of intercooling... assuming you've got the fuel delivery for it.

Crazy projects are fun... like putting a ZE in a MX3 and turbo'ing the thing.
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Old August 10th, 2002, 10:53 PM   #41
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As for the Honda camp stuff...
Did anybody mention they are using things such as Methnol, High quality 120+ oct. racegas, etc?
Not to mention they are tuned for the those special fuels (Pump gas can very ALOT). And if I'm not mistaken, I'd bet thats how J.B. got his High comp. FE3 to take 20PSI (plus good intercooling, etc.).

Has anybody noticed the aftermarket pistons sets for turbo cars? (MR2 turbo, DSMs, etc.) They are mostly 9.0:1. On modern pump gas, 9:1 isn't that hard to deal with.
With a good quality piston (incase SH*T happens), Proper intercooling, fuel tuning, ignition advance, etc. 15psi shouldn't be an issue.
On the SHO they run 9:1 and 15psi (with a big compressor SC, no intercooler). But without the intercooler, thats kind of on the edge . I hear of many people snapping cranks, cracking pistons, spinning bearings, etc. But all of those problems are detionation related (I don't care if everything is forged aluminum and titanium, with detionation any motor will blow).
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Old August 11th, 2002, 02:54 PM   #42
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No argument from me on any of that.

A KLZE can only take you to 5 psi in a non-intercooled setup, but a KLD will only take you to about 8 psi. Chad is intercooled. The wonders of intercooling... assuming you've got the fuel delivery for it.

Crazy projects are fun... like putting a ZE in a MX3 and turbo'ing the thing.
Intercooling is great, but there are other ways of removing combustion chamber heat besides reducing static compression. Ceramic coatings, colder plugs, better head cooling [oil and coolant], fuels with higher specific heat values, water injection, et al. I hesitate to say any of these engines can take up to x psi because the setup seems to make a huge difference. Two KLDE's with T04E compressors that I know of that have been extensively tuned [yours and Manny's] are limited to 5psi due to lack of fuel. Darin has run 8-9psi on stock injectors for quite some time now. What's the difference? I firmly believe that the T04E @ 5psi is just putting out more mass flow [due to increased effeciency] than Darin's T3 compressor at 8psi [do the flow maps for that thing, it's way off the map...]. I wonder how much intercooling affects how much boost you can run in that respect, as mass flow will increase at x psi of manifold pressure.
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Old August 11th, 2002, 11:14 PM   #43
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It's a tricky game, there are many ways to play it.

Water injection works, but past a certain point it gets ridiculous and you lose power because there's too much water vapor in the intake charge. Remember that every unit of water vapor in there is taking away space that could have carried fuel or oxygen. Even before you flood out the engine with water your power potential will peak and drop as you increase the water content.

Ceramic coatings are still a mystery to me. The laws of conservation of energy and mass says that you can't make energy just disappear. The waste heat that goes into a ceramic coating has to go *somewhere* but where is that? The ceramic tiles that protect the Space Shuttle on atmospheric re-entry are amazing; you can take a blowtorch to a 1-inch cube of the stuff until the entire thing is glowing orange and then immediately remove the torch and pick up the cube with your bare hand, without getting burned. The cube will still be glowing orange in the center but the surface will be at ambient temperature. Did all the heat energy get radiated away as light? I guess that's a question for another day. At any rate, I understand the use of coatings for *insulation* purposes, keeping heat confined to a particular area, but I definitely don't understand ceramic coatings for heat *dissipation* ...

Anyway, intercooling is *extremely* effective. Remember that every one degree of temperature in the intake charge is reflected by one degree in the exhaust. Removing heat from the intake charge gives you obvious, directly measurable benefits.

Special fuels are OK for special events, but you can't really rely on having them all the time. An air/air intercooler is always there, just like the turbo is always there, as opposed to water injection, nitrous, anything else with consumables...
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Old August 12th, 2002, 11:00 AM   #44
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Another thing to remember about hondas is they wind pretty high in the RPM range, and the higher the engine revs the more boost is can stand (Cylinder pressures tend to drop after the torque peaks).
This explains how Vortech can make something like 296 WHP on a stock B16A. The cent. SC makes boost on an expodential (it square the boost every time the rpm doubles), so it only deliveres the specified boost at the very top end.

Turbo can be programed the same way with a good EBC.
You could calculate eff. by reading the torque curve on a dyno sheet, and efficeincy can be translated back into compression ratio. Then you would have a graph of CR Vs. RPM, and that would tell you how much more boost you can run through the power band. Thats alot of work, but its POSSIBLE.
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Old August 12th, 2002, 11:19 AM   #45
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I've thought about whether that was a smart thing to do or not. I guess it would help...
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Old August 12th, 2002, 11:36 AM   #46
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It's a tricky game, there are many ways to play it.

Anyway, intercooling is *extremely* effective. Remember that every one degree of temperature in the intake charge is reflected by one degree in the exhaust. Removing heat from the intake charge gives you obvious, directly measurable benefits.

Like Corck said- Intercooling shouldn't be considered icing, its really part of the cake.

Also another secret to the vortech kit...AIR to WATER IC!
Very nice- but more $$$, complex, and space (2-3 gal. tank) than a decent air to air. And now with such devices as the N-tracooler, Air to Airs can be just as efficeint (just like loading an A to W with ice, will have to say C02 cost money, ice is cheap).
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Old August 12th, 2002, 12:10 PM   #47
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I know this started out as a motor generic talk but i have wonder, IIRC the KLD has no cam overlap at all and the KLZE has some miniscule amount of overlap.... how does cam overlap effect boost levels you can run with otu accounting for CR issues.... like if someo ne were top place a ZE cam in a KLD w/ a turbo.... good/bad/indifferent?

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Old August 12th, 2002, 03:03 PM   #48
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The "Turbo" cam was mainly designed to take your money (when sport factory cams do the best job).
Using a turbo with mild sport cams (like the KLZE) should work pretty well. It may let you run more boost, letting some turbos work more in their optimum efficeincy range...
All and all turbo cams are at best a "black art".
Truly depending on engine flow, turbo type/size, and luck (there are alot of factors that can make or break the concept).
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Old August 13th, 2002, 07:39 AM   #49
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Unfortunately I've been gone for a week and a half and this is one of my fav. topics. I'm also at work so this will be a short response.

I personally would prefer slightly higher compression with a reduced amount of boost to increase rev speed and retain a higher mid/low rpm torque while the upper end power/work will remain the same as the low comp. high boost engine. Correspondingly with the extremely efficient design of our chambers and accurate timing of dohc's it is more than reasonable to run 9.2 or 10:1 compression with an excess of 20psi and timing correction. I have stated in past posts that there are now hundreds of people running 4v modular fords with 10-20-30+psi that have very similar comb. chambers and 10.5:1 compression ratio while the 2v mod motors have bad detonation problems with this same setup. Now I'm not saying anyone should do this without extreme precautionary measures, just stating that it has been done many times over.
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Old August 13th, 2002, 08:36 AM   #50
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nice reading.....this will be sticky
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