State.of.Prime

I have a daily driven 99 LS (USDM) thats getting up there in mileage and without sacrificing its reliability im looking to swap the motor and transmission, along with the cluster because Im in Canada and don't like the miles too much...

I researched quite a bit on this forum, and have decided to go with a JDM B20B with a P8R head, and an ITR LSD transmission with a final drive of 4.7. Aside from better options or reccomendations, I am wondering what ECU to run, if its better to run OBD1 or 2 etc.

I did read that OBD1 runs a b20 "lean" on this forum, but am utterly confused as to what that means.

EHondaJDM

running lean means the air to fuel ratio is lower in fuel

if you run obd1 and use some bigger injectors you will be fine
too many people just try to throw a b20 in with stock injectors and it just dont work right they have bigger pistons and need more fuel


when u get the b20 make sure u get the b20z
it still says b20b on the block but its newer and have higher compression
you can tell what it is by the mammoth of a intake manifold like in the pic

State.of.Prime

I was originally considering the B20Z but here in my area it costs 200 more for the complete engine. The B20B im planning on is not the 9.6.1 compression motor nor the 8.8 compression one.

The b20b with a p8r head has a compression of 9.2.1 because it has a different head thats deshrouded to 84mm to match the pistons, and 33mm valves similar to the ones on a v-tech head, also it only has a two-layer gasket. It does not have the knock sensor either. all of this info I found on this website.

My choice for this b20b was mainly because it seems to be the best bang for the buck. I'll be getting a port and polish job, new timing belt & water pump. Im hoping the money saved on the block would probably go towards that.

What size injectors do you reccomend? And what else would I need as far as fuel pump and ecu for bigger injectors? Again I want to itterate im not looking for crazy horsepower, just a dd with a little more torque then the b18b has, I'd prefer to keep it as OEM as possible.

Also I have the bottom end of a b18c1 lying around in my garage, and was wondering if any parts for there would be useful to put in my new b20 swap? I'm told the JDM's dont have some sensor in the oil pan that you need to run on North American ECU's.

Could I run this engine on my stock LS obd2 ECU?

EHondaJDM

You could run the stock one but it won't run great ull need a tune they need a little more fuel

The b20z im talking about is a b20b it says b20 b on it its just higher compression that's what the pics are of its the best bet they're cheap

State.of.Prime

Okay, so then your reccomending to just go for the b20z?

My reasoning for the p8r head was that any advantage of the b20z could be replicated on the cheaper engine from simply changing the pistons to the PHK's that run on the higher compression, and that the p8r head would be more ideal overall. I could simply hone the block .25mm and get the stock 84.25 phk's in there. Only potential problem with this i notice is that the blocks with PHK pistons have knock sensors and the p8r head does not.

If I were to change the pistons to PHK would I then need to put a knock sensor in? Or would the deshrouded p8r head that runs a higher compression than other b20's be fine with a slightly less convex dome on the pistons?

EHondaJDM

You lost me with the whole switching pistons and stuff, you'll want a knock sensor with the vtec and the b20z has it with it. Like I said its still stamped b20b and its the best stock block u could use. My boy ran 13.8 with just a exhaust and intake

State.of.Prime

Okay, to clear it all up. there are three types of b20's, arranged from two varieties of pistons (the P3F low compression & the PHK high compression) and two different heads (P75 from the b18b with 31mm valves, & the P8R exclusive to b20's with 33mm valves).

With these combinations of parts honda could have made 4 different b20's, but they only produced 3. Two of them with the P75 head and either P3F or the PHK pistons, and one with P3F pistons and the bigger P8R head (the P8R also has a 47cc combustions chamber). The high and low compression difference you are talking about is between the b20's with the p75 head.

The P8R head has a bigger combustion chamber (that has been deshrouded to 84mm, and possibally deeper) and bigger valves of the 33mm size. This combined with a 2 layer gasket that comes OEM for this engine, results in a compression of 9.2.1, which is slightly lower than your high compression b20 with the PHK's yet it is also higher than the low compression b20 with the P3F's.

I have purchased a b20b with a P8R head, I am looking to rebuild it for a reliable daily driver. My questions to you guys here at honda tech are:

1) will the PHK pistons make P2V clearance in the P8R head (without any milling)?
2) b20's with PHK pistons have a knock sensor, If I put PHK's in will I need a knock sensor? Or is the knock sensor only necessary for the P75's shortfalls?
3) What is the limit of any mill work I can do (if any) without adding a knock sensor?

My apologies for being incoherrent at times, talking honda also gets me excited