Would it work? Some of the 80's 200sx's came with a CA20E, Would the crank from this fit into a CA18DET, essentially stroking it to 2.0L? Or Coule you just throw the whole CA20 Block w/ a CA18DET Turbo head in your engine bay? Just a question I've had for a while Thanks,

Hi, it is possible, over here (Germany) there is a guy running such a conversion (CA20DE crank in CA18DET block) but i don`t know which pistons he is running(he is using stock pistons either CA20 orCA18). And the question is how will it hold up if u are running high horsepower, cause his car is running at 250hp.

you can use the stock CA18 pistons with the CA20 crank.

I don't know how it will hold up under high horsepower applications though. : )

You may also be able to modify the CA20 block to accept a CA18DET head, but the problem with that is CA18DETs have oil jets that squirt oil onto the back of the pistons to cool them from temperatures related to boost. Without these it may mean piston meltdown. Same goes for CA18DE blocks and non turbo RB blocks... so people have melted pistons trying this... but had a little fun beforehand.

you could always add the oil jet boss' onto the CA20 block (it would be pretty easy), and then maybe use the girdle off a CA18DET to help the bottom end out, but your still working with a block that has too thin of a sidewall to be strong enough for big boost. The CA20 uses a weaker block, and since it's SOHC I dont' even know if you could stick the DOHC head on it. I have seen a CA20ET done up with a CA18ET head and turbo, but I never saw numbers on it.

As far as if you used a CA20 crank you would have to come up with custom rods if you wanted to keep the CA18 pistons, and even if you made custom pistons you have to move the ring land too far up to get the wrist pin re-located by 2mm (which is what it takes) so it's not really worth it or safe.

My answer was just to bore it 1mm over and make a CA19DET, which still loves to boost and since it has a short stroke still it can rev forever.

Hey Okisil80, who made your front bumper? I've seen it a couple times around the net, but I never knew the manufacturer.

Looks to be a Border bumper?

I recently assembled a CA18DET with a friend who Paul (Movingviolation240) knows, and who frequents the FA boards.

I noted that the crank and rod bearings also specified for CA20 on the package ( as well as CA16) so the crank should fit, ( I had heard earlier reports of possible problems with journal and pin width).

The CA18DET block is said to be the strongest and I believe it is the only CA block to have the oil squirters. The bore x stroke on the CA20 is 84.5mm x 88mm versus CA18 which is 83mm x 83.5

CA20 rods are weak so you would have to use CA18DET rods which are the same as CA18DE rods. If using these, the piston is going to swing 2.25mm to far up, and past the deck since the rod is designed for a 83.5mm stroke and the difference in 88 vs 83.5 is 4.5 mm and that gets split between the top of the stroke and the bottom.

Youw could move the wristpin location up 2.25mm on the piston since you would want to have a set of forged pistons made anyway and wristpin location is commonly altered in custom pistons. However, having looked at quite a few CA18 pistons, it doesnt look like there is enough room between the bottom (oil) ring groove and the wristpin bore to move it up 2.25mm. 1mm could be done leaving you 1.25mm to find elsewhere. This could either be done with a headgasket that i 1.25mm thicker when compressed than the stock one. or you could take 1.25mm off the overall top ring land still leaving you plenty of material for strength. (thin top ring lands make the engine not suitable for boost and this is a major detail of the QR25)

You may have noticed that the CA20 is 84.5mm bore and CA18 is 83mm. You would need the 84.5 bore to get the full 1974cc of the CA20 but the usual overbore that is still good for boost on a CA18 is the 84mm bore that Paul and Ray have done. This will net 1950.3cc. Since boring exponentially increases the displacement and stroking only increases it linearly, you will always get more out of an equal ammount of overbore vs. stroke.

Assuming 200hp/liter (360hp on a CA18DET) the additional 150cc would yield about 30hp. The usual figure for hp/boost on a avg. (2.0L) 4cyl. is 7hp/psi or about 100hp/bar above and beyond what the engine makes already. So figure about 4 extra psi or .3 additional bar of boost to make the same 30 hp.

Also 30hp could quite possibly be found elsewhere with much more ease such as in a large throttle body, ported/polished intaker and head and many other things Plus you are losing rev ability. But when all said and done it IS an additional 30hp Hell, maybe even more with the right accompanying mods.

Sean D.