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Discussion Starter · #1 ·
When they do B20 engines and swap them into our car they usually keep GSR block and use the B20 head right?

Does this setup retain piston oil squirters that are in B18C1 engine?

Also is the main reason for doing this just increased displacement and how does it alter the compression ratio compared to a factory GSR head and block ?
 

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When they do B20 engines and swap them into our car they usually keep GSR block and use the B20 head right?

Does this setup retain piston oil squirters that are in B18C1 engine?

Also is the main reason for doing this just increased displacement and how does it alter the compression ratio compared to a factory GSR head and block ?
No. It's the block that is swapped, and a vtec head is used.
 

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So the B20Vtec is a B20 bottom end(short block) & either a gsr or B16 head & cams. And yes, the increase in displacement is what yeilds more HP & TQ. However, there are no oil squirters in the B20 bottom end. B20 also cannot rev as high, safely, as a GSR or B16 can with stock pistons & rods. The B20 also doesn't have an oil cooler. But it's not that easy. You also have to do other modifications. There are good threads here & on other Honda/Acura forums detailing the step by step procedures.

As for the compression ratio, that depends on what B20 bottom end you get. 96/97-98 uses lower comp pistons. Where the 99-01 motors have higher comp pistons more comparable to the B18b pistons. Around 9.6 - 9.8-1. If you stick with the stock pistons.

It's quite expensive to build a B20V these days. Plus you HAVE to spend money on tuning.

A good used GSR motor and ecu is a way better option. And a Stock GSR motor will last longer than even the most meticulously built B20V.
 

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Discussion Starter · #4 ·
Seems like scarifice alot building a B20 B16 hybrid or whatever they call them. Oil squirters are something I would want. Not being able to rev as high seems like another big drawback.
How much more displacement do get out of B20 B18 hyrbid block?
Is the stroke longer or just mainly the fact the bore is bigger ?
Couldn't just take a B18 and bore it out or put a stroker kit on it and achieve the same thing?
Also are the B20 hyrbids not lasting as long because they do not have oil cooler and or squirters?
 

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A GSR bottom end (short block) has a bore & stroke of 81mm x 87.2mm & displacement of 1797cc. A B20B has a bore and stroke of 84mm x 89mm & a displacement of 1973cc.

A stock, non- type R B18c motor makes about 170hp & 128 TQ to the crank. Where as a B20Vtec tuned, usually makes around 200HP and 145-150 TQ to the crank. Or more.

As for the displacement it's about 176cc difference.

The b20 has a larger bore of 84mm & a longer stroke of 89mm. So the main reason you can't safely rev as high with the same reliability as a stock GSR motor is because of piston velocity. The shorter stroke of the B18C motor lends itself to revving higher safer. With less piston velocity.

You can only safely bore a B18 so far without weakening the sleeves in the block. And this is the main failure point of B18/B20Vtec setups. The sleeves crack.

You can resleeve the B blocks. I've heard stories of people taking the bores close to 2.5L. Or higher. With Like darton brand wet sleeves. But that costs a lot of money.

And these were mainly for race applications. And would not pass emissions testing.

Honestly, the best options for more power safely is either a B18C1 from a GSR. Or doing a K20/K24 swap. K swaps are more expensive in a swap chassis like the DC2/DC4. So for a straight bolt in, the B18C1 is the best bet.

But I'm not saying no one should do B18/B20Vtec conversions. I personally just wouldn't do it on my daily driver.

Like if you want to build a car for fun on the track, that never sees daily street use, then yeah. It could be fun and a good learning experience.

But Honda knew what they were doing when they made these engines. They all serve a different purpose. One is for an entry level teg(B18B). The other for a small SUV, the
CR-V(B20B). And the other (B18C) for high revving performance in the GSR.
 
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