Worried About Overbore on L20b

[510SSS]

Hey everyone, I have my L20b at the machine shop right now and I am building a L21 long rod. I decided to order .40 over L22e pistons which have a 88mm bore. Now I am having second thoughts, I am getting the block sonic tested for cracks ahead of time. Does anyone have any experience with taking an L20b block out to 88mm? Is it dangerous, what precautions should be taken?

[datzenmike]

Look at it this way 3mm sound like a lot but it's only 1.5mm or 60 thou from the wall all the way round. Two thumb nail thicknesses.

[Zeusimo]

I Hear Ppl Bore To 89MM Everyday

[510SSS]

Whew that makes me feel alot better, I hope my block handles it well.

[Laecaon]

Well the sonic testing is the smart thing to do, that should also reveal if its safe to go to 88mm

[metalmonkey47]

Hey everyone, I have my L20b at the machine shop right now and I am building a L21 long rod. I decided to order .40 over L22e pistons which have a 88mm bore. Now I am having second thoughts, I am getting the block sonic tested for cracks ahead of time. Does anyone have any experience with taking an L20b block out to 88mm? Is it dangerous, what precautions should be taken?

 

If no cracks, no concern. As long as you're running N/A on a straight block you should be absolutely fine. But time will be the real test.. 

 

My LZ only has an 86mm bore because it was built with every intention of heavily boosting for a 210 race car. Bought it from the builder for a good price and have a solid motor that will never, ever break. Smaller bore for sidewall strength.

 

You should be fine. 

[EricJB]

3mm (.120") should be fine. Your biggest enemy will be heat. If the engine is mild, no problem. If you really put the heat to it, over time the cylinders may distort and go out of round, making the rings unable to stay seated. Blowby and oil burning will be the result. but that could be 60 to 80k down the road anyways. Good luck. 

[jser12]

I did a 30 over with no problems. What's a little bit more? Haha

[datzenmike]

3mm (.120") should be fine. Your biggest enemy will be heat. If the engine is mild, no problem. If you really put the heat to it, over time the cylinders may distort and go out of round, making the rings unable to stay seated. Blowby and oil burning will be the result. but that could be 60 to 80k down the road anyways. Good luck. 

.

As I said only half that is removed from the cylinder bores. It's not that much.

 

If really concerned about heat get a Z series water pump. They have larger impellers and are bigger inside. A three core rad....

[510SSS]

Already got a three core rad, thanks for the tip mike I think I will order a Z pump for the engine. The block passed the sonic test, and it is really thick, so I think i should be able to be bored out to 88mm with no problem.

[laotsu]

there are z pumps all over Windsor PnP, why order a new one? what machine shop are you using? You know aboot Rebello and Troy Ermish?

[Son_of_a_Datsun_Guy]

I decided to go a different route (with some insight from troy ermish), and I'm having him build a Z22 to actually be a 2.1L....

 

bore the z22 to the correct size for a stock KA piston and then run a 6" rod... keeps you from having to do significant boring to an L20 and supposedly runs with less shakes (I like it when motors purr)

[datzenmike]

there are z pumps all over Windsor PnP, why order a new one? what machine shop are you using? You know aboot Rebello and Troy Ermish?

To be clear a Z series pump like from a Z24.

[laotsu]

To be clear a Z series pump like from a Z24.

yup, bunches out at the local yard.

[510SSS]

Why order a new one?, because every single part on this engine is new, I have tried using second hand parts and they always fail on me. Ya i know about Rebello and Troy, talked to him on the phone for an hour the other day about the build, great guy. Sounds like an awesome Idea Son of a Datsun, I was thinking about going to 89mm and using a KA piston as well. troy told me about how he builds his long rod motors. However, I felt that using a Z22e piston would be the simplest because it was actually originally made to be used with the Z20e long rod so there would be no wrist pin modification needed or anything. I'm using Paul's Empire Head Shop in Santa Rosa. He's a super professional guy, highly recommend, he ported and built my cylinder head as well. Thanks for the replies all.

[Stoffregen Motorsports]

You don't need a wrist pin mod if you're running the correct KA piston.

 

If you're really worried about bore distortion, have the machine shop use a torque plate when they hone it.

[datzenmike]

Why order a new one?, because every single part on this engine is new, I have tried using second hand parts and they always fail on me.

New is fine but original Nissan (even used) is better that most reconditioned crap out there that are often a failure right out of the box.

 

 

However, I felt that using a Z22e piston would be the simplest because it was actually originally made to be used with the Z20e long rod so there would be no wrist pin modification needed or anything.

It, the Z22 piston, will fit the Z20E long rod but wasn't made for it any more that it was made to fit the L16/18/20B/L24/L26/L28 rods even though it will. The Z22 piston was never used in that combination on any motor. It will fit an L20B crank and rod if the block is bored.

[laotsu]

does Paul's have an L series torque plate?