What is the impact of 0.030 pistons for Yamato racing

[David German]

Where are you finding these blocks ?

[GrandpaRacer]

If everything is equal except displacement, the bigger displacement will alway make more power. This is because more air and fuel gets sucked into the engine to burn and convert to power. The difference between the 2 sizes we have now ( std bore and 0.020 over) is small , about 1.5% and difficult to notice ...but the 20 over motor will develop more power. This is the status quo and where I think we should stay. The commission voted to add a third size, 0.030 over for 2021. This will make the biggest engine 2.3% bigger than the smallest. It should develop 2.3% more power. It will be faster but not 2.3% faster for the same reason a 33 hp Yamato doesn’t go twice as fast as a 15hp A stock motor.

[DeanFHobart]

Question: Who is making the .030” oversize pistons and rings? Yamato or aftermarket?

[GrandpaRacer]

Sleeves are supper easy to replace, Dean you may have a thought here. I told Brewster that I would be willing to fund a run of sleeves at LA Sleeve and then resell them. Or sell them to APBA.

[Matt Dagostino]

Hi John............when i sucked a wrist pin clip in my good Yamato 102 at the last Grass Lake Nationals CSH final, over the winter i approached TJ about putting his sleeves in the engine vs. just getting another block since the gouge was to deep for any oversize piston. If i remember the cost of the sleeves with labor was pretty high and we went with a replacement block. I understand that sleeves (like forged pistons) are made from a different metal then what Yamato uses and can create different performance results........maybe better, maybe worse!! As a non-motorhead i kinda think the .030 piston is the better route. But maybe i just have cabin fever like most of ya'll

[GrandpaRacer]

Wow, does this mean TJ already has aftermarket sleeves available? To replace a sleeve we heat up a block sitting upside down. When it reaches the right temp the sleeves fall out. To put a new one in. you reverse the steps, and line up the sleeve and it falls in place. if you miss align it, repeat.

[guedo499]

I remember having dinner with Russ Hill and we were talking about efficiencies - one or two percent type of stuff, like true-flat bottom of the boat, sharp edges, etc. I was being a bit nonchalant about trying to go for the last couple of percentages, so Russ decided to tell me a story. As I remember it, he was the CEO of a larger company that happened to sponsor an indy car team and he gave an example: 2% off the pace in the Indy 500 is four laps down. This resonated with me and I still remember those words when I have a boat flipped upside-down and stink-blocking the bottom (we all know how much fun that is).

Additionally, when trying to set a record, you only need to beat the existing record by two-tenths of one percent (.002) - if you've ever ran for a record, you know how hard it is to beat the record by that .002. I did a quick count, and I think I've beat an existing record, but not by enough of .002, at least 6 times - it's heartbreaking.

[GrandpaRacer]

Guedo, I did a calculation and on a 1 mile course, in a 60 mph class if you are 1% faster than boat #2 you will beat him by 16 boat lengths! My calculations are the 2.3% increase in power will give almost a 1% speed advantage.
John Adams

[seanp3]

The bottom line is these pistons needs testing to find out if there is any real benefit going 30 over. If the APBA is going to be the supplier of these pistons will they donate to someone willing to do some testing for them?

[Big Don]

I doubt APBA is going to be the supplier. Just my hunch.

My mentioning was only to say that Mark really does not care if it's handed off to APBA .

[pav225]

Be sure to submit your thoughts to the SORC and volunteer to be on it next year.

[Big Don]

I'm assuming that everyone that is all worked up over this has already gone to .020? If the increase is that important you must have already taken advantage of it.

[mercguy]

I'm assuming that everyone that is all worked up over this has already gone to .020? If the increase is that important you must have already taken advantage of it.

that's what I am assuming...……..

[guedo499]

I'm assuming that everyone that is all worked up over this has already gone to .020? If the increase is that important you must have already taken advantage of it.

Kilo motors 100% .020 over; race motors, mostly standard and won't change them - I'll do what Pavlick said and will let them enlarge themselves the natural method. During racing, there are so many other variables other then .010 size piston. Anybody remember the OMC .040 over - supposed to be stupid fast? Pretty sure it wasn't, only the .030 was fast.

[GrandpaRacer]

Right about the 0.040 OMC, something about those pistons was different that affected the performance. Very disappointing. Either they expand more or were heavier. I don’t recall but my poor old guy memory is that they were heavier.

[Joe J]

Oversized cylinders are one SMALL part of the Yamato equation. There is a west coast driver that runs 300 ssh and C hydro with his sealed engine. He is extremely competitive.

I would take a great prop over an oversized bore every day of the week.

Joe

[GrandpaRacer]

It is my understanding that this whole situation was predicated on the fact that sleeves are not available from Yamato. I can understand why used ones may only be available as used blocks but Ricky are new ones available? Anyway if we assume they are not available from Japan and racers have old worn out 20 over motors, there are only two choices for fixing the situation. One is to allow boring out them further ( the 30 over option) and the other is to find a different source of sleeves. Both these choices require allowing non OEM parts, either Wiesco pistons, rings and wrist pins or LA Sleevs 302 sleeves. Both companies are in the business of making after market parts. Some one will have to step up and verify these parts meet APBA specs. The 30 over choice changes the parity within the class increasing the spread between first and last place and will open up all the records to new challenges. The non OEM sleeve will keep the class parity and provide a permanent solution to the wear-out problem. Costs will be similar but parity in the class should be more important than cost anyway. Last year I had an OMC A motor rebored and purchased new Wiesco pistons costing me $400 total and I did all the assembly work. On the other hand my son bought a one off new sleeve for his Konig from LA Sleeves for $200.
If you have a strong opinion on this let your commissioner know. The impact is mostly on those of you running standard bore motors. If allowed the fast guys will do like our team and immediately bore at least one motor 30 over and then decide whether we do the rest. A few years from now they will be requesting the Commission to approve 40 over motors.

[Big Don]

As they say in some parts of this country, "the $hit is out of the cow", It passed and is moving forward.

[GrandpaRacer]

Don, with a change like this that will upset parity in the class, shouldn’t the racers get a chance to vote on it? I’m not that familiar with when the racers get to vote on changes.

[DeanFHobart]

I agree.... LA Sleeve is the way to go... they could make them for both the 102 and 302 (321).... and even for the Y80. Of course they would need to be machined with the ports.

[pav225]

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[pav225]

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