Static vs Dynamic CR

[Cheromaniac]

Dr. Dino Savva, thank you for advice!

[darkcorp]

I want to see a cut and shortened rod.

They are not cut. They will be resized like this

You cannot safely shorten the connecting rods to the degree required

Those pistons are very thick. Piston crown is about 7 mm thick. Distance to top compression ring is about 10 mm.


So I could razer pistons too. I guess 2 mm can be cut, so I will need to shorten rods by less than 6.5 mm only.
There is a company not far from my city that resizes rods for one of our russian car. They usually do it by 6 mm for $50 for a set of 4 rods. I talked to them and they said they could try to shorten jeep conrods.

[Russ Pottenger]

Not getting it. Why would you want to do this?

[darkcorp]

I live i Russia. We do not have custom forged jeep pistons here. And our currency is 2x times devalued now.

[Cheromaniac]

I know you're trying to save money but I can't help feeling that this is a false economy and you could just end up blowing the engine. My main concerns are that the rods would be weakened and I seriously doubt they'd be perfectly straight without any twist or imbalance in them.
This might work on old farm diesel engines that only have to operate at very low rpm but in an engine that's designed to run to 5250rpm, I can only see trouble ahead.

[darkcorp]

Thank you very much for that reasonable answer.
In 2.5 years of driving my jeep I never reached 5000 rpm. Usually I drive 1500-2000 revs in city and on highway. Sometimes I push it to 3000-3500 when need to pass someone.
Anyway I will revice my stroker budget. Thank you.

Why don't you sleep so late?

[jeepxj3]

Russia, parts and goods are very expensive and labor is nearly free.

Interesting approach to engine building. Something to learn.

[darkcorp]

Bull's-eye!
I work as a trader in a bank and my monthly salary is only $500. Thas is bigger than mean salary in my region. Year ago it was more than $1000 and was sufficient.
So if I buy custom pistons in USA for $500, I need to pay for delivery extra 150-200 bucks. The russian pistons above cost $50 for a set of 4 with rings. It does matter. I don't have deal with gov budget slealing and drive 15-year old jeep that sucks money, so I don't want to spend much.
I also have aircraft building education and have some auto engine tuning experience. For example I've build 2 cyl. 4 stroke engine which pistons run one by one, not together.

[Russ Pottenger]

Thanks for clarifying your situation darkcorp, puts a new perspective on the obstacles you have to overcome.

[Cheromaniac]

Thank you very much for that reasonable answer.
In 2.5 years of driving my jeep I never reached 5000 rpm. Usually I drive 1500-2000 revs in city and on highway. Sometimes I push it to 3000-3500 when need to pass someone.
Anyway I will revice my stroker budget. Thank you.

I'm all in favour of using ingenuity instead of $$$$ to solve a problem. As long as you accept that using those Russian pistons and shortening the rods would be a roll of the dice, you can make a more informed choice.

[darkcorp]

I've found new combo for me.
I could buy sweet old Sealed Power H802CP30 Hypereutectic Pistons and resize rods only by 5 mm. That seems not a big deal.
Actually nobody likes H802CP pistons now because they give too big quench. In my case I can regulate quench by rod length. I will have zero deck clearance and ideal 0.043 quench on these pistons. And they cost less than $200 with delivery. BTW I have no need to modify small end of the rod to use bigger pin. And maybe no need to dish pistons.
What do you think?
One question more: what piston ring set should I buy for them?

[Cheromaniac]

Sounds like a plan, and you'll need 1.50mm x 1.50mm x 4.00mm metric size rings with the H802CP pistons.

[darkcorp]

In my country I found Sealed Power E-925K Piston Rings, they cost $90. Are they good?

[Cheromaniac]

Yeah they'll do nicely.