11.6 compression with stock exhaust?

[leper421]

Over the winter I plan on putting sohc pistons in a spare dohc engine, then swapping the engine once it gets warm again. Most of my limited funds will go into building the engine, and my car right now has stock exhaust. Will high compression with restictive exhaust be a problem? Will I just not be able to get all the potential power out of the engine, or is it really bad to do this? I will be upgrading the exhaust and header sometime in the future, but probably not before I'm done building the engine.

Also, for anyone who has done the piston swap, will the OE rods handle the power, or should I upgrade them too? Do I use sohc rings, or dohc?

[MikeS14240sx]

I don't really see why the exhaust will cause a problem. The potential power would be less but i dont think you will be causing damage running stock exhaust. But for your own piece of mind maybe you should install a test pipe to free up some exhaust flow. They can be made farly cheap which is perfect with your limited funds.

Sorry can't help you with the rod and rings question.

[NotAMonte86]

Over the winter I plan on putting sohc pistons in a spare dohc engine, then swapping the engine once it gets warm again. Most of my limited funds will go into building the engine, and my car right now has stock exhaust. Will high compression with restictive exhaust be a problem? Will I just not be able to get all the potential power out of the engine, or is it really bad to do this? I will be upgrading the exhaust and header sometime in the future, but probably not before I'm done building the engine.

Also, for anyone who has done the piston swap, will the OE rods handle the power, or should I upgrade them too? Do I use sohc rings, or dohc?

11.6:1 is pretty high. Will 93 octane be sufficient?

[Aries]

No.I run 11.0:1 and have to mix 104 with 93. 1 galon to 10 respectively.The car runs like a turd on straight 93 octane.

You will likely have to replace your rods very soon after the swap if you intend to run on pump gas.It will detonate and pit your pistons, as well as causing a pressure feedback that the rods were not designed to handle.

[Movingviolation240]

the stock rods are safe, but only if you don't detonate, maybe some '90 pistons would be a better better since they have lower compression out of the box, or you could shave the tops down a little bit.

You would also have to use SOHC rings in the SOHC pistons.

PaulOrlando, FL

[APEXi240]

There are multiple people in my town with high compression running pump gas....unless its a Nissan thing. Hondas run fine all day long with 11:1+ compression on pump gas.

[illusion]

it's all about cooling, combustion chamber design, mixture, and ignition timing.....

93 is enough for 12:1 in some engines....

87 will run 10.5 in some engines... but others need 91.... there are other factors...

Jeff

[lateralmotion]

aries, when you say that it rides like a turd on 93 octane gas, describe what exactly do you mean, please, ; and also is your 104 gas leaded? because i can get 110 gas for a lot cheaper than the 104 here, but it's 110LL, low-lead, so having leaded gas wouldn't be great for the 02 sensor