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I often get asked why I haven’t swapped my OEM Honda B21a1 in my 91′ Prelude for something with more power, like a H22 or F20b or even a K-series. My response is usually because of “cost” or “the car is fast enough for me” but that’s just my take on it. I know there are lots of people who want to go faster and want more power. So I thought I would put together some information on what’s necessary to do an H22 or F20b swap.
None of this is new information, of course. People have been swapping H-series engines into the BA4 chassis for decades. People, like Sean Tydingco (1funryd on Preludepower.com) have already made H22 swap checklists and he has even made a business out of the popular swap (go check out 1funryd.com). One of my favorite Prelude’s of All Time, the one you see featured in this article, is Ryan Seiler’s 91′ Prelude which he did a F20b swap back in 2014. So like I said, I’m not reinventing the wheel here.
But let me take a second to mention the elephant in the room; The K-swap. We are going to ignore the K-swap option in this article, as well as the other B-Series swap options that are out there. There are some who have pulled off the K-swap. It’s not impossible, but with so little support for this swap it might as well be. You literally have to fabricate everything to make it work and even if you pulled that off you will either have an oil pan that is one inch off the ground or a hole in your hood. You’ll also be running 17″ wheels and will be at stock ride height. These are trade offs that don’t make sense for 99% of us.
So before we start talking about what you need, lets talk about the difference between the H22 and F20b. The H22A1 was offered in the US, Europe and Australia in different versions. Basically, the H22 for the 4th Gen Prelude Si VTEC made right around 190 hp (187 hp to be exact) and then Honda offered the H22A4 in the 5th Gen Preludes that made right around 200 hp.
The F20b came in two versions for the 1997-2001 Accord in Japan. It came in an automatic version, which was good for 180 hp and a standard transmission version which put out 197 hp. The difference between the auto and manual versions were that the manual version used bigger cams, intake and throttle body of the H22.
So as you can see, the H22 and F20b are very similar, however there is one BIG difference between the two; The H22 cylinders are lined with FRM (Fiber Reinforced Metal). This FRM material made the cylinder walls extremely strong, but are hard on steel and as a result, the piston rings have a tendency to wear prematurely. This is why you commonly hear stories about H22’s burning oil. F20b cylinders are steel, and are not known to burn oil.
Pricing for these two engines are similar. Basically, expect to pay $1000 for either a H22 or a F20b manual. However, you can pick up a F20b Automatic typically for around $600. You can either leave it alone at the 180 hp output, or upgrade the cams, intake and throttle body and get the output of the manual. I love the flexibility the F20b offers.
When it comes to mounts, both the H22 and F20b mount the exact same way. With that being said, the F20b will require a post mount from a 4th or 5th Gen Prelude. Lots of companies offer mount solutions. Expect to pay around $400. Here is a set of links.
1Funryd Mounts – http://1funryd.com/products.html
Chedda Auto Mounts – https://www.cheddasauto.com/apps/webstore/products/show/6891812
Innovative Mounts – https://innovativemounts.com/collections/all/products/88-91-prelude-conversion-engine-mount-kit-h-series-manual
Explicit Speed Performance Mounts – http://www.explicitspeedperformance.net/ESPHAMMK.html
You can use your stock traction bar (front subframe), however I would strongly suggest looking to get an aftermarket traction bar to give you more room to sandwich in the larger engine. The companies listed above offer traction bars. Again, expect to pay in the $400 range.
Now we need a transmission. Lots of options here. You can go with the regular H22 trans, which does not come with a limited slip differential (LSD). They can be found around $500. Or you could go with the T2W4 which rocks the LSD, but comes in at $1000. No matter which tranny you get, you’ll will want to change out that clutch and throw out bearing. Maybe even throw in a lightened flywheel. Lots of price difference with these products, but you can find a package deal for a little less than $400.
Lets shift gears and get this tranny to work with our chassis. We need the shifter box and cables from a 4th or 5th Gen Prelude. You can also use Accord cables from the 90-96 5-speed models. These are pretty easy to find on eBay or your local junkyard. Expect to pay around $150.
Ok, we got an engine, transmission, mounts, possible traction bar, shifter cables, it’s time for some engine management. Whichever engine you pick, you are going to need the wiring harness that it comes with. So make sure your engine comes with the harness or you’ll be on eBay making another purchase. You will need an ECU that will work with VTEC. You can run the stock H22 ECU (P13). It’s plug and play with 90-91 Ludes. If you have a 88-89 Prelude you will need to convert to OBD1 with a conversion harness. You could also run a chipped P28 ECU (very popular) or an ECU from Hondata. ECU’s are around $120 or if you go the Hondata route, it’s around $400.
Time to get all of this power to the ground! We need axles! The easy and cheap way is to run Accord axles from the 90-93 5-speed model. I have had lots of luck with axles from O’Reilly’s. I would start there. They should only be about $60 each. You will also need the 90-98 Accord half shaft if using the Accord axles. Keep in mind, the Accord axles will only work with 90-91 Preludes. 88-89 will need a hub conversion to work. Aftermarket axle companies like https://www.raxles.com/ and http://www.gatorracingaxles.com/ can make you whatever you want for this swap, but you’ll be paying for it.
There are other upgrades that you may want to consider. Clutch slave cylinder, clutch line, timing belt, water pump, timing belt tensioner, spark plugs, spark plug wires, distributor cap and rotor. Although it’s a lot easier to replace these parts with the engine out of the car, I would run what came with the engine to make sure that your engine is good. Once you have established that you have a solid motor, I would install these recommended maintenance parts.
So let’s add this up…
H22 or F20b Manual – $1000
Engine Mounts – $400
Traction Bar – $400
T24W Trans. -$1000
Clutch and Flywheel – $400
Prelude Shifter Cables – $150
P13 ECU – $120
Axles – $120
Half Shaft – $50
That puts us at $3590 for the swap. That’s pretty good! Keep in mind most of my numbers are on the low side and not including shipping and tax and all of that jazz so just round up to about $4000 for everything. You can find stuff for cheaper, especially if you are willing to get a little risky with where your parts come from. Local junkyards and Facebook market place come to mind. Just be careful.
So there you have it. Everything you need to put 200 hp under hood. I hope you found this write up helpful. If you did, I’m glad. Don’t forget to follow us on YouTube and Instagram.
Later.
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