I posted this 2 years ago.....

i feel differently now, and i havent even read this post


thanks


Modified by simple4012 at 4:15 PM 4/8/2004

 

Get the best of both worlds.....

resleeve to 84mm pistons....

or B20 with block girdle from Z10...and I dunno....if it really worries anybody ....get the block tapped for the oil jets....

 

.....thanks a lot! I've waited a long time to finally hear someone speak the truth!

 

The friction coefficient of the engine goes way up with that "small" change in in rod length to stroke ratio.

 

your right it does go up......1.025 %

 

I drive a LS, so I do agree what you're saying about the R/S ratio. The point doesn't lie there.

We must put the following into consideration when revving high. I know because I have first-hand experience. I even have pics to prove it. Been there! Done that!

Here are the things that the GSR/ITR have that LS need for high revving:
- block girdle/main cap bridge
- more balanced crankshaft (ITR has 8 counter-balance, GSR 4 or 6?)
- stronger head studs
- lighter valves (ITR's)
- special coating on piston walls (ITR's)
- tighter clearance
- oil squirters
- bigger oil pan
- higher capacity oil pump

It all comes down to LESS VIBRATION = LESS FRICTION = LESS HEAT = LESS WEAR = LESS DAMAGE.



[Modified by Project X, 3:23 PM 3/28/2002]

 

thanks guys, i asked a similiar question on another thread about ls.vtecs. I got an ls block and I want all JUN headwork, but they were acting like it was a sin to rev high on a ls block, thanks, i feel safer now about my build up, im sticking to he ls block but getting it resleeved to 84.5 mm and new pistons rods etc. but im glad someone finally broke this issue down. maybe i should add that the block is in my garage, not in the car yet, i got a SiR-II B16 in the car as of now.


[Modified by DOHC93DxCoupe, 12:04 AM 3/29/2002]

 

I have rev my LS Vtec to 9K with no problems. I do however have a fully built head with the proper internals. So if its built properly, should have no probs whatsoever. But Even then, I feel the ls vtec makes no power after 8500 rpms. I need to go to a dyno soon.

 

The R/S Ratio is not the only thing that people talk about.

A big reason why CRVtec motors can't rev high without problems is because most people do not put the effort and money into putting the proper oil jernels that the Vtec motors have. So people rev the motors up no problem, then 5k down the road they start frying rings and etc etc etc ...

Personally i'd rather take an ITR Block and bore it out to 2.0L+ and resleeve it and run a nice 84.0MM high comp. piston

Just my 2 cents tho

 

I think your math is flawed. You haven't covered the physics of rotational energy properly. There may indeed be a 1.025% difference in ABSOLUTE r/s ratio - but this has no reference whatsoever to the inertial forces that are generated on the crank as a result of high revolutions. The crank is travelling in a circular motion and as such will be generating centrifigal forces at each rod journal - which in turn creates vibration (counterweights or not). These forces increase exponentially as r.p.m.'s increase - making a 1.025% difference a lot bigger. Add to that the previously mentioned differences in valvetrain weight, the effects of Nikasil liners and such and well....you know

 

wow! ...how many years did it take you to learn that??

btw, i like your sig...very amusing

 

What is LS/VTEC?

A quick tutorial for anyone who doesn't already know.

LS/VTEC is using a B18A or B18B block (referred to as an LS block, even though it was found in the RS, LS, and GS) and mating it with any of the DOHC VTEC heads- the B16A, B17A, or B18C. The principle is to use the larger displacement of the LS block (READ: higher torque) and mate it with the high end power of VTEC. I'm also sure you've heard of CR-VTEC, which is a very similar idea. It uses the B20Z block of the CR-V (NOT the B20A of the Prelude Si, for reasons that will become obvious later) to achieve the same effect, only on a grander scale. What you end up with is an engine commonly referred to as a "Frankenstein" setup, and it's all the rage these days

Why would Honda do that?

So why in the world would Honda put us in such a situation- having to build these incredible motors all by ourselves? Why would they knowingly decrease displacement and torque in a car being manufactured to be faster than its lower-trimmed breathen?

Look at it, too, from a manufacturing standpoint- Honda is already making the higher displacement B18A and B blocks (blocks are identical, only difference was in the head), so why go to the extra time and expense of developing and manufacturing a separate block, especially if it will decrease output?

The answer is easy: R/S.

What is R/S?

R/S is the abbreviation for rod to stroke ratio. It is the ratio of the length of the connecting rod to the length of the piston stroke, or the distance the piston travels from the top to the bottom of its stroke. As the ratio gets lower, the amount of stress on engine internals increases exponentially, killing long-term reliability. The higher the number is, the slower the piston is traveling, killing power output.

The ideal R/S is 1.75:1 (Three cheers for the B16A, at a near-perfect 1.74:1!).

Why a low R/S is bad for reliability

A low R/S means the rod will be closer to a horizontal angle on its upstroke. This means that more of its force will be pushing the piston horizontally, rather than vertically. What does this mean for your engine? Two things.

1. There will be more stress on the sides and in the center of the rod, rather than on its ends, leaving the rod more vulnerable to breaking. Picture a straw. This is no special straw, just an ordinary drinking straw. Is it going to be easier to bend this straw by applying pressure onto its ends, or at its center? Now think of your poor connecting rods..

2. There will be more stress on your cylinder walls. Once again, the rod is pushing the piston at a more horizontal angle- right into your cylinder walls, rather than up and through them. The risk here is double: A. Putting that piston right through the cylinder wall. B. The cylinder wall will actually flex under the pressure, causing the shape to turn from a circle to an oval or oblong shape. This causes the loss of the seal created by the piston rings. What happens? A small amount of oil could slip past into the combustion chamber. Bad things happen from here: The oil gets combusted, leaving nasty carbon deposits in your combustion chamber and exhaust ports- not a good thing for flow or valve sealing.

It's also important to note that as the RPMs increase, so does the amount of stress on your engine's internals.



What is power, exactly, and how do Hondas make it?

Warning: Once you see this, you will never look at horsepower and torque readings the same again, especially after you think about it.

P= (TR)/5252

P= power, in horsepower
T= torque, measured in lb/ft
R= Engine speed, in RPMs

Therefore:

Horsepower= (torque x RPMs) / 5252

Try it- pull out a dyno and see what you get.

So from this, we can conclude that if we increase torque or engine speed, we will get more power, right?

Remember that, it's important...

Now how do Hondas make power? Our tiny little 1.6-1.8L engines aren't exactly oozing spare displacement and creating gobs of torque, are they? Hondas make power through revving, and revving high. So why does everyone place so much emphasis on creating torque? It's because all these bolt-ons you see advertised won't raise your redline, but they will increase torque. There's nothing wrong with squeezing every last ounce of torque out of your engine- you should. But trying to get torque from more displacement in a Honda is like trying to fill a swimming pool using a squirt gun. You'll never get enough for it to be useful.
The Alternatives
So now consider these-

For the same price tag as that B18C, you could do this: B16A1 (JDM Integra XSi) Cylinders bored and sleeved to 86 mm Forged rods and pistons, 12.5:1 cr

And have the following results: 1789cc of displacement 1.74:1 r/s ratio 150-160 hp

For the same price as an LS/VTEC, you could do this:

B16A1 Cylinders bored and sleeved to 86 mm Forged rods and pistons, 12.5:1 cr B17A crank

And have the following results: 1891cc of displacement 1.68:1 r/s ratio 180-190 hp

The most expensive part would be the B17A crank. New, I was quoted $977.23 from my local Acura dealer, and I have yet to see one used. However, since the B16A and B17A deck heights are identical, the rods would be shelved parts- no custom machining (cheaper!). Also, most piston manufacturers do make 86mm bore pistons, to any desired compression ratio.

It should also be noted that both of these options would employ the cable tranny found on the B16A1. If your car is already a cable tranny, no problem. However, if yours is a hydro, expect to invest a couple bones in a new tranny (CTR, maybe?).

The Advantages
So what has Johnny gained, really? Why go to the trouble of assembling an engine when you could just buy a B18C or slap a VTEC head on an LS block?

Advantages over both the B18C and LS/VTEC

-For the same price, you already have a built engine, including: forged rods and pistons, sleeved cylinders, and high compression pistons. Comparably built, a B18C or LS/VTEC would be much more expensive; first you would pay for the engine, then pay for the build-up.

-Oversquare engine geometry (bore>stroke). This is another one of those little things that will increase your redline and reduce stress on your engine internals (read: reliability). With the B16A crank, bore/stroke would be 86/77. With the B17A crank, bore/stroke would come to 86/81.4.

-Better rod/stroke ratios. Although you lose 8cc of displacement (so what?), the r/s ratio of the B18C alternative would improve from 1.58:1 to a near perfect 1.74:1. The increase in redline would more than make up for the loss in displacement. In the LS/VTEC alternative, it would improve dramatically from 1.54:1 to 1.68:1.

Additional advantages over LS/VTEC

-Uses a B17A VTEC crank. The VTEC cranks are far superior to their non-VTEC counter parts, and perform much better at high engine speeds. This is due to (among other things) better lubrication and better rod bearings (although these would more than likely be upgraded, regardless).

-Uses a B17A VTEC block. No more machining, tapping, and drilling the B18A/B block to accomodate VTEC. Much more user and installer friendly, much more reliable.

-1891cc of displacement. Remember how excited everyone was to get an extra 37cc of displacement for their VTEC motor? Well, this is an extra 94cc. Nearly three times the increase, and 57cc more than an LS/VTEC, with all the aforementioned advantages.

Between the superior engine components and geometry, and properly built (and with an adequate valvetrain), I can see this engine spinning to 12K RPM all day without a hitch. There aren't cams out there that could use 12K, but I'll bet you could. And that speaks volumes about the engine.

The Disadvantages
By now, everyone is pretty familiar with my favorite saying: If it was all that great, Honda would have done it in the first place.

-The combustion chambers in the head will have to be machined to accomodate an 86mm bore. While this isn't a huge problem or really especially costly, it does present another problem. It increases the size of the combustion chamber. Combine that with the B16A's or B17A's relatively short stroke, and getting a piston dome high enough to generate a respectable compression ratio starts to look pretty big. This creates two problems.

1: Valve to piston contact becomes an issue with any high dome piston used in conjunction with any high lift/ long duration camshaft. Survival here depends on a good valvetrain and knowing when to say when and not getting too aggressive when choosing a compression ratio. At 12.5:1, it should be safe, and pump gas would still be an option. Good tuning of the valve timing and an experienced engine builder will also help immensely.

2: A high dome piston isn't all it's cracked up to be. Sure, generally the higher you go with compression, the more power you can make. However, once the piston dome becomes too high, you start to run into combustion issues. Think of the combustion wave as it is first ignited in the chamber. With a smaller or flat dome piston, the combustion wave has a much easier, much more direct route across the piston and combustion chamber. The higher the piston dome gets, the more it is in the way of this combustion wave. For these two reasons, I wouldn't go above a 12.5:1 compression ratio with this engine. The piston dome would simply have to be too big to be practical.

-When I first started exploring the possibility of boring the cylinders, I talked to many people who had bored theirs out to 84mm. The first question I asked was why stop there? Why not keep going to 86? 90? Larger? The largest you can bore the stock cylinders is 84mm. Any larger than that, and the cylinder walls become too thin. So what about sleeving? When working with a larger bore application and sleeved cylinders, you can only go so far before from above, the cylinders begin to look like an Audi logo. The achilles heel of the engine has now become the head gasket, and the space between the cylinders. To remedy this, a thicker head gasket is necessary (further increasing our dome height problem), and strong head studs (such as the ARP) to reduce flex.

So What?
This motor has potential. In a serious build (aggressive cams, head work, bolt ons, etc...) and some good tuning, I can see this engine hitting 210-220 hp without too much difficulty. Couple that with its good geometry (less stress on your engine internals- reliability!), and this would far and away be my choice over an LS/VTEC. It does have its weak points, but I believe that with an experienced engine builder by your side, they shouldn't present a problem at all, and are nowhere near as big an obstacle as a bad rod ratio is. If I were starting from scratch, trying to decide what to build, this would be it. Cheaper price tag, better geometry, superior reliability, and more potential. So, Mr. Hondaman, what's it gonna be?


http://www.hondastyle.com/news/wmview.php?ArtID=5

 

I think it all depends on how you plan on useing your engine and what kind of budget your on. I mean why argue about motors that other people are building. An engine will only take so much abuse. sure some more than others. Some people build motors to last several 100 thousand miles others to be the fastest thing on the street. Sometimes to get what you want you have to sacrifice one for the other, and thats okay. Alot of people can't afford to go out and buy an ITR or ITR swap. So they build frank motors oh well. You got your type r and they got there fast civic or integra. Maybe the Frank is faster maybe it's not. When you build a ls or crvtec your probably not worried about it lasting 200k miles your probably more concerned about power and the cost of getting that power. Sure I could of saved my pennies and bought an ITR swap and probably had a quick EK. But I chose to build a crvtec. Not only for the Torque but because I built it. And to me that was the best part of the project. Your type r may last longer than a frank engine and it may not I guess that depends on how each is abused and how well each is built . We allready know that honda knows what they are doing. And there are several people that have proved that they can build frankinstein's well. So no matter what kind of motor you build on whatever budget your on. If you do it right you will be happy with the results. MY 2 CENTS.....

My engine
B20b block bored .5mm over balanced crank ,forged 12:1 pistons ,forged eagle rods ,Z10 girdle ,Itr oil pan ,Itr oil cooler ,B20 oil pump(same part # as ITR's),ITR crank pulley, B16 head ITR valves,springs,and retainers, Ctr cams, # angle valve job and port and polish, opened up combustion chamber to 84.5mm, ITR intake manifold and throttle body, RC 310 injectors, moroso oil catch can with no pcv, chipped p28 ecu mugen program, 00 si tranny, cm stage 3 ,fidenza flywheel, AEM intake, JDM DC header, custom exhaust. And it's fast as hell!!! Because thats what I wanted.

Thanks
Skippy

 

Jesus ... that guy typed a book. Edit copy, edit paste into .txt file for later reading ...

 

Again, there is a TON of mis-information here.

Someone needs to really make a webpage that is true to the point.

Let's really know why LSVTEC's fail.

Reason #1 - Builder is too cheap to invest in some ARP rod bolts.

That's right kids. The LS rods are pleanty strong enough to rev to 9500 rpm. But the rod bolts are the same versions used in the 1.6 SOHC.

You heard me right, S-O-H-C, as in Single cam.

All the LS or CRVTEC's i've ever seen go (blow, destroyed), did not have ARP rod bolts. A $40 part + machine work. At about 8000-8500 rpm, the rods have so much weight places on them that the rod bolt can't hold it together anymore.

#2 - The builder never planed ahead.

Planning is key to being reliable.

Plan on balancing the engine
Plan on buying the right parts for the job
Plan on spending $$ to properly assemble it.

Or plan on doing it again.

That is all for now.

 

 

Well here's something that might interest a lot of you......

It's taken from racingcrafts website and even the JDM guys who race PRIMARILY on the circuit are using the B20 blocks.....

They point out some key things like the 8500rpm redline and such.
http://www.racingcraft.com/media-4.shtml

GO BABY GO!

 

good to see some of the old regulars like RagingAngel come back.

the HT ITR board is starting to look familiar again.

that J's website has some pretty wild stuff on it.

Do you know anyone who has tried that Tsuchinoko chamber tapered intake with big cams and big compression locally? Would love to see a dyno of that motor.

I may order that intake for the ITR when it comes out. At least their pricing isn't ridiculous like that ARC intake.

 

damn! and all this time I thought the piston going through the side of the cylinder wall was due to piston geometry.

yeah...rod bolts....what was I thinking??!!! (slaps forhead and thinks doh! to himself)

I can have a 1.54 rod ratio engine held together and rev it to 9500 rpm 10,000 times and not worry all due to ARP rod bolts.

I guess you can have the piston still go thru the side of the cylinder wall but your rod will still be attached to the crank. What about that for a thought?

BTW use the wrong stretch spec on the rod bolt as you torque down on the rod bolt too much and you can have an ARP rod bolt go just as easily as a Honda rod bolt.

You'd have to be a pretty foolhearty person to rev to 9500 rpm with a 1.54 rod ratio don't you think? or are we talking about a 5 pass trailer queen race motor that'll be torn down after each race?

you can say that again...sheesh....(stops muttering kettle calling the pot black).....




[Modified by Michael Delaney, 9:40 PM 3/28/2002]

 

LOL I'm usually accused of that crime here..... http://209.197.120.239/showthread.php?s=&threadid=5525
http://209.197.120.239/showthread.php?s=&threadid=4971
http://209.197.120.239/showthread.php?s=&threadid=3854

 

Michael D.....

HIGH FIVE!!

WhoHOoo!!

 

Sweet ... more reading material! Right click, right click, copy copy ...

I should publish a book with all the stuff I have collected off these websites over the years. And no credit for any of you!!!

 

I just wanted to say this is a GREAT thread.

 

It's not that easy!! Just because you did some level 1 algebra, you think you have this R/S Ratio thing figured out. I'm not trying to put you down, or insalt you, but there is a lot more to it than that, you've got to through in some Trig, Physics, Dynamics, and Strength of Materal calculations with that algebra!


You are correct.... there is only a 1.025% difference in R/S Ratio between the LS and the B18C engines. But did you know that 1.025% difference in R/S Ratio results in 3% difference in static force on the cylinder wall alone. (Static Force is a force that is applied with no fluctuations or movements and with no impact. This type of force provides to least amout of stress and fatigue issues) I simply found that out by using trig and angle calculations. Now, if you throw in fatigue stress factors, friction forces, moments of inertia, angular velocities, acceleration, impact loading, repeated loading, amoung other things... that 1.025% is going to have a hugh effect. Some of those factors increase exponentially. I'm not going to take the time to run through those numbers too, but the that 1.025% difference in R/S Ratio just may end up resulting in a 15% difference in allowable loads, maybe more.


Here is an example on how percentages can sometimes be misleading:
You remember how all those Firestone tires were blowing out and causing accidents? There were a ton of them, a bunch of law suits, and a huge up roar about firestone being terrible tires. Well, Firestone has several different kinds of tires, and it was only one type of tire that they were having the problem with. And in that one line, do you know what percentage of them were defective? 0.333%
That makes your 1.025% seem a lot bigger, doesn't it.


There is a reason that honda didn't just put a vtec head on the same block. If they could, believe me they would!! It would save them a **** load of money and they would turn a much larger profit. Honda doesn't have a bunch of idiots designing there engines, trust me.


Now I'm not saying that a LS/Vtech wouldn't work. But they are not as simple as everyone thinks. And there are a lot more issues than just the R/S Ratio. To do it right, it would diffenetlly be cheaper to by a B18C5, and you may even be able to bore it out and still squeeze in under the price of a good LS/Vtech job.


Nothing is ever that simple. I'm an Mechanical Engineering student, and you would think that would make me understand and be able to figure things out easier. But the more I lean, the more I realize that there is so much more to things like this that I ever know existed. There is more to this one little example than I even probably realize and understand. In fact... **thinkink** ...this may be a decent senior design project!



[Modified by PSU-TEG, 8:44 PM 4/2/2002]

 

Hey Micheal Delaney:

How's this. I have a 1.54 r/s, and almost daily it sees 9,900 rpm. 1 full year of use so far.

You like apples? How's them apples.

Yes, damage can occur on any built or otherwise engine. Many people do not know to use the ARP rod bolts on their LSVTEC or CRVTEC, and they build it cheaply. That was my point.

Now stop being a smart ***, and instead, be productive to this thread.