engine rebuild - upgrade questions

[dhen]

Hi,

I'm going to take my engine to a machinist here for a complete rebuild. I've got another exhaust cam and a 4-port head that I'm going to use. I've been looking into using oversized pistons. Would using, say, 84 mm pistons require retuning? What would the the benefit really be of using forged pistons if I don't plan on running more than 10 psi of boost?

What are some other upgrades that you would recommend? I'm not trying to build a race car but I am looking for things that can be added that aren't too expensive since he's going to be tearing the engine apart anyways.

Thanks,

Darian

[themadscientist]

10 PSI is pedestrian, cast slugs would be fine. An overbore should not need a retune but the cam swap would.

[bentvalves]

yea anytime you can get away with a cast piston do it.

i.e. not gonna be bouncing your car off limiter at track days @ 20 psi for prolonged periods.

[dhen]

Point taken about the pistons. Are there any other upgrades that would be good? What's the deal with the Cometic head gaskets for example?

Thanks,

Darian
Modified by dhen at 11:54 PM 11/8/2008

[bentvalves]

dont waste your money man I run 20 psi on a OEM paper gasket.

they have excellent fire rings and are a worthy gasket no doubt.

[dhen]

Thanks, I appreciate that. I'll just stick with the regular gaskets then.

By the way, I've been searching all over the internet, and the only oversized pistons I can find are forged. I don't plan on running a lot of boost, but I want more displacement, are there any other options?

Thanks again,

Darian

[ca18detgabby]

you might check out the specs on some honda or other company 1.8L engines....... if the fitment is close....... and have it machined to that.

[dhen]

you might check out the specs on some honda or other company 1.8L engines....... if the fitment is close....... and have it machined to that.

Stupid question, but I really don't know. But anyways, wouldn't that be a problem with getting these pistons to fit the rods?

As far as the machine work, it's a total rebuild, so the size of the bore is up to me.

ca20det?

[ca18detgabby]

idk about CA20 which is a SOHC........ but there was never a CA20DET...... less you stroke a CA18

there have been a post or two about using B18 pistons with little bore work IIRC. if you hit up the search button you may be able to find it.

[Ca_Silvia]

10 PSI is pedestrian, cast slugs would be fine. An overbore should not need a retune but the cam swap would.

Even for small cams like a 256, you have to retune?

[themadscientist]

You are changing lift and duration of the open valve. You need to retune.

[bentvalves]

Thanks, I appreciate that. I'll just stick with the regular gaskets then.

By the way, I've been searching all over the internet, and the only oversized pistons I can find are forged. I don't plan on running a lot of boost, but I want more displacement, are there any other options?

Thanks again,

Darian

If your dead set on forged pistons go ahead, but for the amount of boost your looking to run there isnt any need, hell you could run 20psi on cast pistons. And the .5mm bigger piston isnt going to net you any noticable results, turn your boost up 2 psi however, and it surely will.

[themadscientist]

also the bigger bore will lower your compression allowing you to run higher boost.

[Thebighouse111]

If i wanna build a CA18DET from the block is that a good idea or should i buy a stock, already set up CA and upgrade the internals and everything?

[meminto]

Depending on how many compression points lower you end up with will affect off boost response, this is the trade-off unfortunately...

Bighouse - I am unsure what you mean, but I assume you mean procuring parts rather than a complete motor to start off with? Depends on your budget really, but I would suggest buying a complete motor. Upgrading/rebuilding depends on what you want as an outcome...