Wisconsin S2k

For those who were reading, it seems like this post was missed by some of you. This guy here kinda knows what he's talkin about.

Anyways, note he said you could probably do it, but drive it like an F20C and eventually you'll break a rod. obviously the rods in the F22C are different than those in the F20C. I assume they are probably longer, hence the extra .2 liter displacement.

Also note what he said about loading and the pistons.

Elistan

Actually, the rods are shorter - it's the crank that has the larger radius, given the additional stroke. Just lengthen the rods and you'll have the same stroke, just further away from the crank.

There's all sorts of engine design considerations considering the rod length to stroke ratio that has some sort of bearing on how fast the engine can spin. From what I can understand about the subject based on my readings here, as the rod/stoke ratio becomes smaller (ie, a long stroke with short conrods) the stress on the engine (be that cylinder side-loading force from the piston, or some sort of strain on the rod itself, I dunno) increases.

http://www.hondanews.com/CatID2069?mid=200...141254&mime=asc
For example, the F20C has a stroke of 84.0mm, and a conrod length of 153.0mm. That's a ratio of 1.82mm.
The F22C1 has 90.7mm stroke and 149.65mm rods. That's a 1.64mm ratio.

One quick search says that a 1.65 to 1.80 ratio is ideal, with 1.50 being the absolute minimum.

UL, could you help out my understanding on engine dynamics and explain why the faster revs would more likely lead to conrod failure, rather than something involving the piston directly? Is it simply that the extra distance the rod has to travel, and the therefore higher accelerations is experiences, are too much for the rod material to handle? If so, are there stronger aftermarket rods that could be put in to compensate for this?

Thanks!

Stratocaster

FYI

There is a F22C1 installed inplace of a F20C (There is a thread posted on this in S2k Talk). It has been dyno'ed. It made 9K with out any problems (so far). They found that the MY02 ECU dumped in a ton of fuel between 8300 and 9000, so the power dropped off. Next up is fuel tunning.

In short, someone is trying this.

CrazyPhuD

here's more update....I found out more from him after I referred him to HTG....while he has had it in...he's doesn't push it above the 8200 much because of fear that something will pop. Originally the idea that I was told was that he wanted to have the extra revs if he needed it at certain points in the track rather than having to shift. It's aparently something that he doesn't go into much, because of the percieved risk of engine damage. So while it occasionally may go above 8200 it's not on regular basis and as a result I wouldn't draw too much of a conclusion about reliability. I understand his conservativeness here...once you pop one engine you generally don't want to pop the second

Elistan

"Second," eh? So he already blew one? Bummer.

Stratocaster, do you by chance have a link to that thread? Is this the one you're referring to?
https://www.s2ki.com/forums/index.php?showt...dpost&p=4795335
I'm surprised that the 02 ECU put in too much fuel for the 2.2! I was hypothesizing that the known richness of the earlier ECUs would be compensated by the additional displacement and airflow of the larger engine... Hmm.

CrazyPhuD

he blew the first one...but it was a 2.0L....toda camshafts, and a bunch of other mods...

CrazyPhuD

Also remember the intake and exhaust have not be changed from MY03- to 04+ really. A 2.2L at 8200 rpms will be flowing similar cfm to a 2.0L at 9K....you may run into additional airflow restrictions buy spinning the 2.2L higher....

Elistan

Good consideration to keep in mind. But that's easy compared to the task of getting to 9000rpm in the first place.

ultimate lurker

High rpm stresses on the bottom end are usually the worst at the top of the exhaust stroke. The piston wants to continue upward while the crank is just starting back down. The rod, rod bolts and wrist pin are in tremendous tension at this point (as is the wrist pin boss on the piston, but this is rarely the first failure point). Its worst on the exhaust stroke because there is no attendant gas pressure (as on the compression stroke) to help slow the piston. This tension is a function of of the piston speed and the rpm. Both are important because the deceleration of the piston is where the highest stresses are. Its usually the rod beam, or the rod bolts that fail first on Honda engines, although it isn't _always_ that way.

We've generally found that most Honda engines are capable of handling 400-500 rpm over stock on a regular basis for street driving. However, there are prices to pay. On the regular F20C, exceeding 9000 rpm on any regular basis will cause valve retainer problems (as we've seen on some race cars which were never taken above 9300 rpm and no overrevs). But the bottom end is fine. On K20A2 engines, cars that exceed 8600 rpm under racing conditions will break a rod within a couple of races - we've seen it happen to three separate race teams such that it has become a defacto standard to keep stock rod K-motors under 8500 rpm for racing purposes.

As I said, I think an F22 would live with revs to 9000 rpm, but sooner or later you're going to break something. For street and occasional track use, 8500 rpm is generally accepted as safe. For heavy race use, as I said, we won't exceed 8200 rpm until someone starts beating us, and then we'll do it with much trepidation.

UL

ultimate lurker

CrazyPhud, in our testing we've found that power tends to flatten off at 8000 rpm on the F22 and stays flat up to about 8400rpm where it starts dropping, so airflow considerations are important.

UL