Stroker 2.6L

[BORY]

anyone on here ever stroke there H22 to a 2.6 or ever heard anything about them good or bad?? or another ideas for good power?

[NorcoAccord]

I hear about it all the time on ebay or a friend of a friend. I bet its possible but I would be afraid to do that.

[blazenem]

why afraid??^^

[owequitit]

I don't know much about it personally, but 2point6 had a couple H22's stroked to 2.6 liters. They didn't last long.

My guess would be that with the stroke the piston speeds were too high. I don't know if it was hard on pistons/rings/rods or if spun bearings were the problem.

I think he is now a firm believer that 2.44 liters is about the biggest you can go, but you would have to ask him.

[HondaFan81]

Scott Byars from Collective Racing is the guy to talk to about this, he's done it. Do some searches on his username "2point6"

[NorcoAccord]

why afraid??^^

Because one mistake and you can blow your motor if its 2.6. If you want to make a bigger displament motor just get the internalls of an h23 and swap them over and then you dont have to worry as much honda did your work instead of hopeing the guy who is builting your motor will do his homework and have all the geomerty right

[texasvtak]

just get the internalls of an h23 and swap them over and then you dont have to worry as much honda did your work instead of hopeing the guy who is builting your motor will do his homework and have all the geomerty right

Not so right. Id worry just as much with an H23 crank. Oil squirters dont clear it, so starvation is a problem, usually resulting in spun bearings. Strokers are just a gigantic headache for most people in the Honda world.

[v4lu3s]

talk to Frank at Pocket Rockets Racing as well.

[eludedU95]

The problem with stroking a motor is that it changes the rod/stroke ratio. Honda designed these engines to be able to sustain high rpm's. The B16 has one of the best rod/stroke geometry's of Honda's engines therefore whicn is one of the reasons it is one of the highest revving as well. I'm no professional on this subject so here's a link with a bit more info. Here
Google is another good source to find out more info.

[v4lu3s]

a stock b16a is designed to last hudnreds fo thousands of miles. a built race engine is not, its designed to produce power.

[owequitit]

The problem with stroking a motor is that it changes the rod/stroke ratio. Honda designed these engines to be able to sustain high rpm's. The B16 has one of the best rod/stroke geometry's of Honda's engines therefore whicn is one of the reasons it is one of the highest revving as well. I'm no professional on this subject so here's a link with a bit more info. Here
Google is another good source to find out more info.

To some extent this is true. However, using a longer rod with the same stroke improves the rod ratio.

There is much more to consider when stroking an engine besides rod ratio too.

Not the least of which is piston speeds.

Ironically, due to the mechanical nature of pistons accelerating down a bore, long stroke small bore engines are actually more conducive to making low end torque as opposed to high end power.

That is one reason you will typically see an undersquare design on small displacement family car engines. It helps bolster the low end. The F22 in the Accord is a good example of this. It is designed for better low and mid range power as top end revability isn't as important to most drivers of this car.

Basically, there are a lot of factors in play when building an engine, and like most succesful projects of large complexity, there is a large degree of compromise and fine tuning so that ALL variables work together in the best way possible to achieve the desired outcome.

What works well in one circumstance, may not be the best choice in the next.

It is what seperates the men from the boys.

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This is just FYI for anyone who didn't understand.

First, some terms:

Bore - the size of the cylinder that the piston moves in. Essentially, the same as the diameter of the cylinder.

Stroke - the amount of distance the piston covers from Top Dead Center (TDC) to Bottom Dead Ceter (BDC).

Displacement - This is the amount of volume moved by the engine in 1 complete revolution.

Displacement is calculated by:

1) Taking the area of the bore (A=pi * r^2)

2) Multiplying it by the length of the stroke

3) Dividing by 1,000(to convert from mm^3 to cm^3)

*Unless you are using inches in which case this step is not needed

4) Multiply by the number of cylinders. This gives us the displacement in Cubic Centimeters.

*You can use the same procedure (disregard step #3) if you wish to use inches.

Now that we know the displacement in cm^3, we can now divide by 1000 again to get the more commonly used displacement in liters.

The "squareness" of an engine refers to the bore/stroke relationship.

Square means the bore and the stroke have the same dimensions. I.E. the J30 Honda V6 available in all 1998-2007 Honda Accord V6s. The bore and the stroke both measure 86MM which makes it "square" as the volume traced by the piston would look like a square 86MM to a side.

"Oversquare" means that the bore is larger than the stroke. This is the case with the J32 that is sold in the Acura TL. It has the same 86MM stroke as a J30, but a larger 89MM bore so the volume covered by the piston would resemble a rectangle laying on its long side or would appear "oversquare."

"Undersquare" would be the case with the J35 that is sold in the Pilot, Ridgeline, Odyssey, RL and TL Type-S. They have a bore of 89MM with a stroke of 93MM. The volume traced out by the piston would resemble a rectangle on its small end standing up like a skyscraper, thus the term "undersquare."

[eludedU95]

^ Good post. I don't know as much about you do on this subject but doesn't sidewall pressure exerted by the pistons on the cylinder walls increase once the stroke is increased beyond stock specs? And would this cause an increased risk of outside rings and ringlands being destroyed because of this ? I still don't understand how you would be able to compromise all the factors you mentioned while increasing the stroke and still have an engine that would last a decent amount of time for a race engine. Although stroker kits on the market may have factored in all this stuff by changing the location of the wristpin on the pistons and such which may be why these kits are so expensive. IDK, maybe you could shed some light on the subject for me.

[gloryaccordy]

Expanding the bore FTW

IMO the best route to take would be...

An F23 block+crank
88mm bore + pistons
2360cc
Rip-snort'n torque!!!
OEM power!!!

Someone threw H22 pistons in an F22 block on an F22 crank, topped it off with a stock H22 head and made 200whp out of the box, with 160wtq...you can't beat the torque! I've ridden in H22s and even though they have the same displacement and higher compression they just don't match the F in torque, especially when the F is properly opened up.

In any case, based on my calcs I'd say 2.360L, or perhaps slightly higher would be as high as one would want to go...

[Gemini]

Expanding the bore FTW

IMO the best route to take would be...

An F23 block+crank
88mm bore + pistons
2360cc
Rip-snort'n torque!!!
OEM power!!!

Someone threw H22 pistons in an F22 block on an F22 crank, topped it off with a stock H22 head and made 200whp out of the box, with 160wtq...you can't beat the torque! I've ridden in H22s and even though they have the same displacement and higher compression they just don't match the F in torque, especially when the F is properly opened up.

In any case, based on my calcs I'd say 2.360L, or perhaps slightly higher would be as high as one would want to go...

interesting info there.....

[owequitit]

First, some more information.

Engines are air pumps. They simply burn gas in the process of pumping and extract energy from the burn to turn a shaft.

The only things that matter are how much air we pump, and that we maintain a proper air fuel ratio.

HP - horsepower is derived by calculating the amount of work done over time. In relation to an engine, it is the amount of work done per revolution.

You will hear a lot of people say that "there is no replacement for displacement" or "HP sales cars and torque wins races." These statements are just not true. These are usually muscle car guys referring to torque. The problem is that torque isn't actually responsible for moving a car. Why? Torque implies a radial force being applied to something. It does NOT imply work. If I place 100lbs of twisting force to a shaft, using a lever arm of 1 foot, I am generating 100 lb/ft of torque. If the shaft does nothing, then I am not doing any work, per the definition of work. If I increase that to 500lbs, and the shaft still does not move, then I am still not doing any work.

That is where HP comes into play. Horsepower is dependent on torque, but also on RPM, which makes it an actual measure of work, because the shaft is actually moving.

The formula for HP is:

HP=torque * rpm
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The first thing that should become apparent about this formula is that we actually have 2 ways to increase the amount of work done.

We can:

A) increase the amount of torque at a given RPM, which is usually the route the muscle car guys take when they increase displacement.

or we can

B) leave the amount of torque generated alone and increase the RPMs. This is the route chosen most commonly by Honda. When coupled with the super high flow heads that Hondas are equipped with, we end up with the high revving, deep breathing Honda engines we have today. They still make a lot of HP, they just do it by turning faster instead of huffing more air per revolution.

Let's try it out and see what we get. Let's say we have a 2.0 liter four cylinder and a 4.0 Liter V8. We will assume that the heads flow exactly the same, and that the V8 makes exactly twice as much torque at any RPM. We will also assume that because it is twice as big, it redlines at 1/2 the redline of the 2.0. That will allow us to cleanly demonstrate the formula. We will calculate torque at a redline of 5,000 for the V8 and 10,000 for the 2.0.

HP(V8) = 250 lb/ft * 5,000rpm
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When we work this out, we get a HP value of 238 HP. Notice that our torque is larger than our HP. That is the result of not being able to leverage torque against a lot of RPMs.

Now the 4 cylinder. It makes half the torque and spins twice as fast, so that is what we are going to plug into the equation.

HP(I4) = 125lb/ft * 10,000rpm
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5252

When we work this out, we get a HP value of 238 HP. Notice that the HP is much higher than the torque. Why? We are leveraging a small amount of torque over a lot of RPM and are thus make more power with less torque.

One of the arguments leveraged against Hondas is that they have no low end torque because the HP is so high. They assume that they must be weak. In fact this is not true. Most Hondas I have driven do just fine in the low end against other engines of comparable displacement. There APPEARS to be a disadvantage for several reasons.

1) The peak torque usually occurs high. That is what we expect to see since their breathing efficiency extends so high into the rev range. This makes them feel comparatively weak to their top end. However, if everything were compromised towards torque, we wouldn't gain much anyway due to the small displacement, and we would lose a TON of top end. Then they would "feel" like a lot of other "torquey" four cylinders.

2) People fixate on numbers. It is an easy way for them to relate things to one another. This analysis can be flawed though.

Look that the F22A4 vs the F22A6 for instance. The A6 shows 10 more HP in the spec sheet which is good, but it also shows the same 142 lb/ft occuring 500RPM higher, which on the surface is bad.

Most people would see this and assume that the F22A6 has less low end. That is wrong. It actually has more. Why? The dual runners allowed less compromise between low end torque and high rpm power. The low runners only have to function to 4800, not 6300, so they were optimized for lower RPMs. Then at 4800 the secondaries open and the runners can now breathe to redline. The larger cam helps marginally as well, and probably helps explain the increase in RPMs for the torque peak. That is why numbers can be deceiving.

The main upside to small displacement/high rev engines is the fuel economy associated with them. Most people assume that you can't have power AND economy, because this is what we are conditioned to believe. That is also NOT true to an extent.

With a large displacement engine such as a big-block Chevy, we are forced to fuel a large displacement at all RPM's in order to keep the engine running. This results in less fuel economy, especially at low power settings where you are pumping way more air than you actually need to accomplish what you are doing, say cruising at 30MPH.

With the small displacement high revving engine, our fuel need only goes up with RPMs. That means that if 2,000 RPM's will accomplish what we need to do, the four cylinder will burn less fuel at that given point, leading to the fuel savings we typically see with Honda. That is also why if you keep them on boil all the time, you will see a BIG decrease in mileage.

There is a lot more to it than that, head efficiency, cam profiles, intake restriction etc, all add to the equation, but for the purposes of a block and this conversation on bore and stroke, we will assume all top end aspects are the same.

The reason you have to compromise your variables is because each individual variable has certain advantages and disadvantages just like everything else in life.

You have to choose among the variables and potential solutions to get everything set up to work together.

For instance, bore.

A larger bore is one way to increase displacement. More bore = more air moved per revolution = more power per revolution. The advantage of increasing bore is that it allows you to increase displacement without increasing stroke, so we can move more air, and keep our piston speeds the same. That is one reason a larger bore and smaller stroke will like to rev more.

Not only are we covering less distance with each stroke, but this allows us in turn to increase the redline more before we get to dangerous piston speeds since each piston is moving less per revolution. This allows us to increase the redline more without having structural worries, but it does not explain how this works in conjunction with getting air into the cylinders efficiently.

What does explain how it breathes better, is the fact that the piston's velocity changes less between TDC or BDC and the pistons maximum velocity. This means slower acceleration at a given RPM, which is conducive to high revolution cylinder filling with a given valve area because the port velocity remains lower for a longer amount of revs.

This has a lot to do with what goes on at the port, which is yet another variable that has to work with everything else.

The disadvantage to increased bore is multi-fold. A larger bore requires a larger piston. A larger piston means more mass, which means LESS revability. As the piston get larger, it also gets harder to get the entire mixture burned, as the flame front only propogates away from the spark plug so fast. If it doesn't get to the outer portions of the cylinder with time to burn completely, you can get higher hydrocarbon emmissions which is bad for emmisions. This would probably only be the case with a really ridiculous bore size though.

As an example, this is the main reason rotory engines have bad emmissions performance. Their combustion chamber is very shallow, but also very elongated. The flame can't burn everything before the exhaust stroke, so there is a much higher concentration of hyrdocarbon (unburned fuel) emmissions.

A larger bore also requires more spacing between bore centers. This results in a larger block which results in a heavier engine. Imagine if we increased the bore by 1/2". That is a HUGE increase, but works well for rounded numbers. On a bank of four cylinders, this would theoretically make our minimum block length an additional 2". Even in aluminum, that mass is going to be heavy. Now we can do things like thinner liners, closer piston spacing etc, but again, that requires still more compromise, and you can only do that so much..

Increasing the stroke on the other hand, has many of the opposite effects.

The increased acceleration away from TDC causes our peak volumetric efficiency to occur at a lower RPM. Since the torque peak on an engine coincides with peak volumetric efficiency, our peak torque will occur at a lower RPM as well. This is good for around town driving, towing, etc.

Why?

The acceleration of the piston is greater, which brings the port velocity to its maximum at a lower RPM. Once the maximum port velocity is reached, power WILL taper off because it physically can't flow any faster. This leads to an earlier power peak, which again is good for the above reasons.