Differences between L15B7 and L15BA?

[nicholasyeti]

It's to my understanding that the B7 in the Si has thicker rods and higher compression but is there any differences in the actual block or head? Why would I buy a built short block from TSP rather than build it myself? I own a 2021 Civic EX with the BA engine in it and just wondering if its worth the ~$5k.

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[dellyjoughnut]

A built short block is only if you want to push for high horsepower numbers. I'm sure you can buy the 5PA rods for the L15B7 and shove those in the L15BA engine which is the same engine I have in my FK7. I wait for another user on this forum to chime in as I have not changed out my stock conrods to the 5PA rods found in the L15B7. The difference in compression ratio exists for 10.3:1 for L15B7 vs 10.6:1 for L15BA.

https://www.civicx.com/forum/threads/lets-talk-about-those-1-5t-rods.71909/

 

[Jason Baker]

It's to my understanding that the B7 in the Si has thicker rods and higher compression but is there any differences in the actual block or head? Why would I buy a built short block from TSP rather than build it myself? I own a 2021 Civic EX with the BA engine in it and just wondering if its worth the ~$5k.

The TSP / CSS block has a lower built. Basically the parts that require detailed attention to tolerances are already shipped to you.
Can you build this yourself? Of course! People have. Cost wise, I am not sure it’s worth the frustration especially when spending that sort of money. Go for it if you must.
The rest of the upper is stock. In fact, when you look at the big picture of building these motors, 92% are OEM-stock! You’re just adding improvements to the weak points. The heads are slightly different in ways I am not specifically certain but people do swap them out.
Even with buying the lower, it’s still a big task to build the rest of the motor but it’s essentially like-for-like swapping. Just don’t be cheap and replace all your gaskets! No sense in blowing up your motor for a $10 gasket.
My 2 cents but if I did it again, I’d still have bought the lower all built.

 

[zacwel]

The L15BA is only in the hatchbacks, for whatever reason. I'm pretty sure the L15B7 is in all the other 10th gen Civics, not just the Si. (Someone double check me but I'm fairly confident.)

I contemplate the same when I think about building my motor. Building myself vs. buying the TSP one. The only major benefit of building it myself, is the sense of personal accomplishment lol. Aside from that, building it myself would be intensive: measuring and double checking oil clearances, making sure the cylinders aren't out-of-round, making sure the crank is good, yadayada. A machine shop, if necessary, would be pricey and more than likely add time to the build with the motor out.

With the TSP built, that all done for you already. You can be sure that everything is installed correctly, tolerances are within check, all that good machining stuff. PLUS!, it has the cylinder support system sleeves for more extra security/durability. And yeah you could get the Darton sleeves and have the machine shop install them for you but that's more time at the shop and more money.

Just my thoughts!

 

[Austin@Wunderladen Racing]

The L15BA is only in the hatchbacks, for whatever reason. I'm pretty sure the L15B7 is in all the other 10th gen Civics, not just the Si. (Someone double check me but I'm fairly confident.)

The BA is only in the hatchbacks (in the US at least) because they were all made in the UK. From what I've seen all of the sedans and coupes are made in Canada. The BA has different rods than the B7 and the Si has lower compression pistons than the non Si although they're both called B7.


To answer OP, engine building is a pretty exact science and requires a fair amount of precision measuring equipment to do right. Buying the tools to measure and assemble everything is not cheap (for quality tools) and if you don't have experience using them it is not hard to make a mistake. That's mostly what you're paying for when you buy a built engine. There is also some work required in notching the bottom of the cylinders to accommodate wider aftermarket rods.

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