Well, while I do agree with you ScreemingZ28 and Bontke.... yes, stroking the motor will make good power, and even with the decreased RS ratio, and faster piston speed, you will see a much, much more positve effect for Power. And if that is all you are after, go for it.

However........

I don't know about you guys, but... If I were going to be spending all this money on building a performance engine (and I just did), would would want it to last. You said it yourslef, ScreeminZ28.... You would go for the power and worry about the 30,000 mile reliability later. So you are admitting that RS Ratios have negative effects on reliability, which is all anyone in this thread is saying.

Now, this is just me, since money is not growing of any of the trees in by back yard, but... Those stroker kits cost a ton. And if I am going to be splending $5,000-$10,000 on a completely built performance engine. I would not want the thing to last 30,000 miles before I have to rebuild it. That is not anywere near worth it to me! I would rather go with the resleeving and boring for almost half the price. And with proper maintance, tuning, and care, it should last way over 100,000 miles. Now, to me that is way more worth it.

All anyone is questiong about stroker kits and RS Ratios is their reliabilty.

Now, if this is an all out race car you are building, and you have another daily driver and/or don't care if it only lasts 30,000 miles or so.... then go for it, more power to you. You will certainly enjoy the power you make from it, but just not as long as I would like for that kind of money.

So anyway, it's all in what you want.... Good Luck!


Oh, and I'll admit it... I am the one that said you should limit you revs to 6,000 or so. But once again, for reliability! If you want a stroker kit to last, you shouldn't be going to 8,000 and 9,000 RPMs. But once again, if you'r not worried about reliabilitly, go for it!





[Modified by PSU-TEG, 7:21 AM 10/14/2002]

 

Smaller piston diameter means a better burn, more power.

About all this R/S ratio stuff. I believe it plays a part in piston ring life, as well as ability to produce power at the higher RPMs. I built a B20/ VTEC recently that has pistons from Endyn that raise the wrist pin up, hence longer rod, to make it the same R/S ratio as a GSR/ITR. These new pistons are also lighter, designed after the S2000 piston (strutted). If you are going to spend 5-7k on an engine, why wouldn't you want to to last as long as possible?

 

Smaller piston diameter means a better burn, more power.

No it doesn't. All other things being equal it does mean a more complete burn, hence lower HC output during emissions testing. What it does mean is less available quench area, limited breathing ability at high RPM relative to displacement, and lower displacement capability and/or engine design and packaging ability.

Everyone understands that r/s ratio can and does play a role in engine reliability, it's the constant back-talk that bothers myself about how important a factor it is in power production. It's not, plain and simple. Sure, if you're designing a motor on your own you'd better be thinking about it, but if you're merely modifying one that's already been engineered, there's 20 other things to spend your time and money improving. All of which are also going to be more effective at helping the bottom line: more power output.

So let's get specific from the supporters of the r/s ratio gig, and nail down exactly what ratio they feel is both streetable and reliable. And please give minimum and maximum values. Oh, and could you also compute the max rod angularity for said ratios while you're at it, just so those without the math can get a visual of what you are concerned about?

 

Just look at what Honda says with their actions. The B18C1 has a R/SR of 1.58, and Honda has it revving to 8200 stock. On the B18B it's 1.54, only .04 lower and the rev limiter is already lower. Almost all experienced LS/Vtec builders know that revving a frankenmotor too high & too often is a no-no for long term reliability. I believe that the B18C1s R/S ratio is already pushing the envelope for revving to 8200+ routinely, and lowering the R/S ratio further without also lowering the rev limit is asking for trouble from piston side-loading and engine vibration. Think/do as you like of course, but I'm not willing to do such an experiment with several thousand of my hard earned $$$, when there is already an easy and much safer path to more power in boring.

 

yup, b18c stroke up to 2.0 is not very reliable. if u guy could remember 93-95 JTCC, all the civic equipped with a b18 2.0 always broke down. when honda switched to accord and used H22 destroke to 2.0, they won the champion of driver/maker. how can a stock block height and 94mm got an ideal rod ratio? i doubt the jun kits reliability(for 29.7m/s avg piston speed?).


[Modified by spoon_ek9, 9:04 PM 10/14/2002]


[Modified by spoon_ek9, 9:19 PM 10/14/2002]

 

Besides all that RS ratio, what are the major benifits of driving a daily driver that will rev to 8,000? It seems like a big mess (taking a serious RS ratio person) to have a car that you need to get in the 6K plus range before it makes a good bit of power and torque. I am a big fan of turbos and low end torque. Lets compare a recent engine that I saw posted on here some where....

B20B
99+ CRV B20Z pistons
Resized rods, shotpeened. Balanced pistons and rods.
1G B16 (89-91) head, milled 0.010in.
GSR Camshafts
ITR Intake Manifold

This engine was built for a turbo and was making 175 HP and 120 ft.lb. @2,200 RPM all the way to 135 ft.lb. @7,000 RPM. Amazing torque curve (not much curving though) for a Bseries Honda. The car didn't have a turbo installed.

BAck to the subject- Compare this to a high revving somewhat built B18C. It seems that the torque from this B20 car will get it moving off the line and all the way down the quater mile faster then a B18C. Where would the benifits of a high revving engine come into play? It doesn't seem to me that you need to rev all that high if you are making power more soon that another engine, right? So then a RS ratio of 1.54 and lower wouldn't be that big of a reliability factor (since you would be making most of the power around a friendly 6,500 RPM) correct? Let the debates begin!


[Modified by Bontke, 8:02 PM 10/14/2002]

 

Timonex, that makes no sense. The Gsr is already pushing the envelope? Better quick driving those ITRs. Same rod ratio. Its all crap made up! My example of a 30K mile motor was an example, not an acutallity. The reason(s) for the lower redline in the LS motor; no vtec, its not going to make power higher up, smaller (weaker) rods and rod bolts, no piston oil squirters, etc. Honestly, the valvetrain is much more sensitive to rpm than the rotating assembly. This sideloading garbage needs to stop. Talk to a pro engine builder that makes FAST cars. They will tell you that the big block 500+ CID 1.2:1 rod ratio is FASTER than the 480 CID 1.5:1 rod ratio motor. Displacement wins each time. If you think that revving to 8200 in a honda is bad with a rod ratio of 1.58, you would not believe these 1.4:1 Fords turning 8000+! I have talked to Bennet Racing, Jon had the fastest Mustang in the nation back in 95, and they have no reliability problems with the rotating assembly on their cars. They limit rpms and use nitrous simply to keep from having to replace the valvetrain after 2 passes. Hondas have a better valvetrain design and can rev to 9000 without wearing out springs. Therefore, you won't have any problems with a bad rod ratio in a honda. I swear, I just need to build a 1.3 rod ratio motor and show people. In conclusion, TimoneX, I am not saying that stroking is "better", as boring IS the preffered method to increase displacement, its just not always a viable option. Stroking is usually much easier, if not the ONLY option available. Big bore motor is better, just not always feasable.

 

I love this guy

 

one advantage of a high redline is the room it allows for shorter gearing. Nobody wants to load up short gears in a motor that can only rev to say 6000, but if your engine can safely redline up to 9000, you can use shorter gears and still have room if you need to punch it in any gear.

 

Screaminz28 I completely agree with you, aside perhaps from the 1.3:1 buildup idea.

Since nobody here is either willing or able to quantify things in unambiguous terms, let’s lay it out with real numbers.

1.82:1 (F20C numbers)
maximum rod angularity: 15.95 degrees
maximum piston speed @ 9000 RPM: 8096 fpm
mean piston speed @ 9000 RPM: 4960 fpm
maximum piston acceleration: 4862g

1.74:1 (B16A numbers)
maximum rod angularity: 16.7 degrees
maximum piston speed @ 8400 RPM: 6981 fpm
mean piston speed @ 8400 RPM: 4266 fpm
maximum piston acceleration: 3938g

1.58:1 (B18C numbers)
maximum rod angularity: 18.49 degrees
maximum piston speed @ 8300 RPM: 7927 fpm
mean piston speed @ 8300 RPM: 4749 fpm
maximum piston acceleration: 4531g

1.54:1 (B18B numbers)
maximum rod angularity: 18.95 degrees
maximum piston speed @ 6800 RPM: 6562 fpm
mean piston speed @ 6800 RPM: 3970 fpm
maximum piston acceleration: 3050g

1.49:1 (B20A numbers)
maximum rod angularity: 19.61 degrees
maximum piston speed @ 6800 RPM: 7033 fpm
mean piston speed @ 6800 RPM: 4238 fpm
maximum piston acceleration: 3283g

Now what does all that mean? Virtually nothing, when you really get down to practical application. The more you compare these numbers the more you'll realize Honda seems to have little rhyme or reason to their engineering targets as far as these r/s ratio influenced specs are concerned. In other words, its not all about r/s ratio to Honda engineers. In fact, its not even a little bit about it. There, no need to guess about why engines were failing in a far off racing series, no need to compare unsimilarly tuned engines with and without VTEC, just no nonsense numbers that illustrate exactly what some people are so overly concerned about. A degree or two here, a litle extra piston acceleration there. All easily surmountable with proper design and execution, as Honda readily proves every day with any one of their production engines under the hood of your car. OF course that's just my opinion, I could be wrong.

 

I have a B18C1 it needs new rings. 83k miles, and I rev it to 9300. Now do you really think I'd be replacing rings right now if I never revved the car past 8200? I think I'd still have 25-30k before my OEM rings lost their seal, to me the trade some reliability for more performance was worth it. I have new slugs & a heap of other stuff going in, but I've no doubt in my mind that I did shorten the life of the rings that came with my car by increasing the redline. I am NOT hear me NOT saying you cannot run a rod ratio of 1.2 or .9 whatever the heck you want, but the physics involve say that when the rod comes closer to horizontal it side loads the cylinder walls more. The higher you rev that motor the more vibration this will create and more force WILL be applied to the cylinder walls. If you're aware of these factors and build knowing the limitations then in some circumstances it may be the trade off for you. The cost, and the more frequent rebuilds are not worth it to me. I love the sound of my engine when I shift at 9k+, and I'm not lowering it.

 

So Texan does that mean you'd feel comfortable taking your B20 to 9300RPM regularly? How long do you think it'll last there? I mean you say there's no rhyme or reason to Honda's scheme then you illustrate my point perfectly. The list of engines you mentioned has a powerband shifting downward, right down the list. Gosh what a surprise, and lower redlines as well.

 

You've missed the point entirely. Stop looking at the redlines for a moment and look at the forces encountered by the engine internals at their respective RPM limits. The redlines were chosen based upon the application and respective airflow capabilities, not the forces encountered by the pistons. The B18C1 redlines just 100 RPM shy of the B16 because it's heads allow it to breath well at that RPM, even though it sees 1.8 degrees more rod angularit. And I didn't bother to bring up the B18C5 as a point because I figured everyone here could make that mental leap themselves... guess not. It, along with the B16B, can safely redline at 9k. Why? Because it's internals were designed to take it, that's why. The rod angularity does not kill these engines any more than it did yours, as is evidenced by that factory warranty. Question: how do you attribute your needing new rings to thrust loading on the ring face? Answer: you can't, its just an assumption you've made to further your argument. I'd like you to post up picks of your ring lands when you have it rebuilt, since those will have also taken a huge beating if the rings are really being worn out by side loading.

The B20 redlines at 6800 and not 9300 RPM for good reason; nothing in that block was designed to spin that RPM. Not the con rods, pistons, rings, cylinder sleeves, bottom end, oil system... NOTHING. The point (once again) is that thrust loading from angularity is, within the confines of workable r/s ratios, a simple point of engineering the parts to withstand the encountered loads. Its the same principle with which everything in your engine was designed, and so far no one in this thread has posted one single real piece of evidence proving otherwise. Its all innuendo and assumption, backed by a lack of knowledge regarding the true aspects of what makes or breaks engine performance.

Ps- Thrust loading increases in frequency with RPM, but not in amplitude. And it does not cause engine vibration.

 

Actually, RPM does increase amplitude. "Force =mass x acceleration" as RPMs increase, the acceleration of the piston will increase, and as a reasult the Force(Thrust loading, as you put it) will increase.

But anyways.... I have heard all kinds of arguments from both sides. And to be honest, I'm not sure which is correct. I have no doubt that Stroking the engine will have a very positive effect on performance. And things will not break due to the extra side loading itself for the lower rod ratio because it is quit small. However when you get into fatigue strength from repeated and reversed loading, these numbers multiply fast, and can very quickly become a problem with relability. And that's what I'm talking about. I don't want to buy an engine that will have problems due to this 50,000 miles down the road. I believe that stroking the engine WILL have a far worse effect on engine life than boring. How much? I don't know.... 90% less, 70%, 50% shorter life? I don't know? Nor do I know if I am even correct.

With that said, I am going to try to prove this debate, either way. However, I don't have a lot of free time, so it will take me a while to figure it out, anyalize and run all the engineering calculations for this. Hell, I don't even know if I will be able to come up with a difinitive answer... that's why Head Honda Engineers get paid the big bucks!

But anyway.... a little help from you guys with some facts and figures for that Stress and Fatigue Analysis would be appriciated.

1. What is the minimum cylinder wall thickness or B18's?

2. What specific type of material are the cylinder walls, pistons, and rods made out of?

2. What is the weight of the stock pistons & rods?

I will try to find these out myself, but any short cuts would be greatly appriciated, given the amount of work I have to do. Thanks

[Modified by PSU-TEG, 11:19 AM 10/15/2002]


[Modified by PSU-TEG, 11:29 AM 10/15/2002]

 

Wow, I'm glad someone hear understands this. Thanks texan. Timonex, think about this, a domestic example. A stock 5.0 Mustang will make power to 5200 or so. CAN you rev it higher? Yes, but you will be slower, as you aren't making more power. Add better heads, better cam, better intake, better exhaust, and you will make power to 6500. Well, you better not rev it there, as Ford designed it for a reason to go to 5200, and it is bad to do anything other than what the factory says. WTF? That is basically what you are saying with this. If we change (hey thats what modding an engine is) parts of the motor, then it will do it. The rings on your car probably went due to lack of oil changes, imporoper break-in, etc. There are a lot of things I would put ahead of rod ratio. You are just taking it too far. Why change anything on a honda motor then? If you change the header, it can't make more power, as honda would have done it already. Same with exhaust. Cam gears, bah who needs em. Honda made the cam gears the way they did for a reason. That is such a typical, "honda did it for a reason, so it can't be done any other way" ricer mentality. Don't take this as a flame, just as a way to try and get you to open your mind.

 

Does anyone have comparitive info for the H22a and H23a on this? I always hear about R/SR with these engines. What's the deal?

 

1.58:1 (H22 numbers)
maximum rod angularity: 18.49 degrees
maximum piston speed @ 7400 RPM: 7267 fpm
mean piston speed @ 7400 RPM: 4404 fpm
maximum piston acceleration: 3661g

1:49:1 (H23 numbers)
maximum rod angularity: 19.61degrees
maximum piston speed @ 6800 RPM: 7033 fpm
mean piston speed @ 6800 RPM: 4238 fpm
maximum piston acceleration: 3283g

 

hey texan, i know how to calculate the mean(avg piston speed) but how to calculate the max. piston speed?

btw, after seeing the data on H22, no wounder honda could easily out power other car in 96 JTCC after they destroke the H22 to 2.0L.

 

deeeesplacement

b20z it is. all "natural". that's some good info. did you make that yourself?

 

Okay so a lot of people are looking into the H23 VTEC hybrid (H23 block,rods,pistons). What are the implications here? If you were lightening and balancing the crank, sleeving the block, and running forged pistons at the stock bore, and the VTEC head had all titanium valvetrain etc...would you be looking at reliability issues? Or would what is being said here still apply, or does the R/SR reallt matter that much on an H23 VTEC?

 

Lack of oil changes?!? BWAHAHAHA

Ford? Again with the Ford comparisons. Screw Ford garbage. When done I will have changed nearly every component in my engine, so that I may do more than what Honda designed. The one thing I do expect to suffer is long term reliability. I have every one of those parts you mentioned BTW and I did not buy them for cosmetic reasons. Now knowing I've modded nearly every aspect of my engine, your post makes no sense whatsoever.

And please save the silly comments about valvetrains k? The first serious mod I made was stiffer Crower valve springs and Ti retainers, & Crower cams. I changed my cam gears too BTW. I'm not into the "Honda did it for a reason...blah blah...ricer...blah" mentality. Anyone would take that mindless drivel as a flame, and if my mind weren't open I wouldn't be building an all motor Honda now would I? Look, I talk about my personal experience with my OWN built B18C1@9300 and you respond with senseless trash about Ford's with a 5200RPM rev limit? Don't you think the 2 engines a just a little bit different?

 

Since I am an experienced engine builder and believe I'm correct here, but at the same time also know that I am not the only informed person on this topic, I will cite an article posted by Michael Delaney at team-integra.net.

"Lower rod ratios produce a larger or steeper angle between the rod and the crankshaft. The rod angle must not be too steep such that it encourages excessive friction at the cylinder wall and piston skirt as the piston travels:"

"a low rod ratio produces a steeper rod to crankshaft angle and MORE PISTON SIDELOADING FORCES against the cylinder wall, as it travels up and down the cylinder. The consequence of a low rod ratio and resultant larger rod angle is MORE WEAR & ENGINE VIBRATION as the engine revs higher and higher: you are eventually forced to use a lower redline in order to prevent engine damage."

There's no escaping physics. The entire article can be found at:

http://www.team-integra.net/sections...p?ArticleID=11

Again, I'd like to stress, I am NOT implying that stroking is all that bad, I AM implying that it's not the best path to more power on a Honda motor. There's nothing stopping you from stroking a B18C1 and lowering the rod ratio while doing so. I will lay money however that it will simply not last as long as a non-stroked motor with the same number of trips to the very same redline. You will naturally make more power lower in the rev range, possibly eliminating the need to rev as high. Kewl you made more power. You'd have done the same thing and more reliably by boring however, and I suspect it would've been cheaper and more reliable.



[Modified by TimoneX, 1:45 PM 10/15/2002]

 

what ?
taller deck ?

in a B16 ?
how exactly would you do that with stock rods ?

 

Seriously dude, I wasn't trying to flame you. I think essentially we are saying the same thing, just to different extremes. First, I don't think rod ratio killed the rings in your motor. Second, I prefer bore to stroke as a displacement method. I am just trying to minimize the OVERSTRESSING of rod ratio when it comes to honda engine development. As I have stated before, there is no power made in the bottom end. Its all a building block for the head and cams. When I am building a motor, I would worry more about head flow and cam specs. Do you know what your head flows? What about the cam specs? The reason I am so adamant is I find a bunch of kids saying, "oh, your rod ratio sucks, you won't make power." Well, if my heads flow more, and I have more displacement, then guess what? It will be faster. THats what I am saying. Yes, you are correct, you do sacrifice longevity with a worse rod ratio. Is it worth even thinking about? Not in any practical sense of the matter. Also, where would you stop? Would you go to a 2:1 rod ratio? Why not? If lower is worse, then higher is better, right? Come on man, chill out.

 

This is a great thread.

I agree with Screaminz28. Most of you guys are WAY over-stressing this whole "rod ratio" thing. Fact is stroking DOES WORK! Even with a bad rod ratio. There's more to a motor than the RSR.

Why not have a happy medium? Small bore increase and a small stroke increase?

That seems like the best answer.