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mattster03

My F20C Swapped Zcar Build Thread

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I wanted to take a quick minute and introduce myself and my newest car project... I am really excited about this car!  I recently sold my LS1-swapped 3rd generation Mazda RX-7 which had been my baby for 7 years.  Lots of hard work went into that car and it will probably be the fastest I will ever own... but for me, I had achieved everything I wanted with the RX7 and since I'm a "project guy" at the core I decided it was time to start something new.  I've been dreaming about a 240Z project for quite some time now and I finally get the chance to start one.  Here's one quick picture of my FD before moving on to talking about the Z project:

 

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Yeah... it will be missed! 

 

Anyway, shortly after the sale my search for the right chassis started.  I was mostly interested in 240Z's due to the styling, but had an open mind for 260 and 280's.  The most important part for me was to find the most rust-free and cleanest I could find.  Although I was searching well within 300 miles of home, a local car just so happened to pop up on craigslist that caught my attention.  An early '74 260Z with one heck of a interesting story.

 

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The reason I say “interesting” is because it comes with an almost unbelievable history.  The odometer says 4,883 miles, it has been owned by only 4 owners previous to myself and the last two of which think it’s the actual mileage.  I was obviously very skeptical on the mileage, but there are little things that help the rumor hold weight.

The car comes with what is allegedly its original license plate… the plate has one single tab on it: ’74.  Now that’s at least interesting, right?  Well the story goes that the original owner purchased the car brand new off the lot drove it for a few thousand miles and passed away shortly after.  The car found its way to the proverbial “barn” where it sat for many years until it was purchased by the second owner who had racing in mind.  It is clear that this car was owned by an old school racer, it has a 6-point roll cage, a unique race switch panel labeled with 80’s-era punch strip lettering and brake ducts made from Campbell’s soup cans… yes, you read that correctly soup cans.

 

Well, if you’re following the story with me, is it possible that the car became a trailered track car only at this point?  It’s certainly plausible… years of racing from a trailer without ever renewing the tabs, it could happen.  Well this owner also passed away and the car found itself once again in a barn in the Seattle area… where it sat until the 3rd owner spotted it and inquired if it was for sale in the early ‘10s.  It did not last long with him as he sold it to a friend who is I eventually bought it from.

 

Whether or not the 4,883 miles is “true”, the best part about this car is the condition… this is really the only other indicator that this car might be the low mileage barn find it claims to be.  For one, the body does not have the classic Datsun swiss cheese rust one might expect from a 100K+ mile car.  During the buying process I carefully examined the car in all of the places I expected to find rust.  Under the floor mats, beneath the battery tray, in and around the hatch, on the frame rails, dog legs, etc… next to no rust.  The dash is immaculate, not a single crack as would be expected from a high mileage Zcar.

 

With all that being said, to be 100% honest, I don't think it's actually <5,000 original miles, but if it isn't, then it's certainly is one of the cleanest 105,000 mile cars if that's the case.  And that's what I'm most excited about.

 

Well unfortunately now is the time I tell you that the car doesn't quite look like that first picture shows... that's what it looked like before the owner before me decided he was going to do some body work, primer the car and then plastidip it "smurf" blue.  Sigh.  Needless to say, I still wanted to make a move on the car and after a bit of haggling, I was finally the owner of an S30 for $2,750 and even had the guy throw in an RB25DE.  Here's what the car looks like on jack stands with about 1/3 of the plastidip removed:

 

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And here are a few more:

 

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There are still a lot of details that I am planning regarding this car.  Currently, I intend to swap an F20C & 6-speed from a 2000+ Honda S2K.  I know this may seem like a strange engine choice to some of the people on this forum, but I am really starting to think that it's a good fit for my goals for the car.  I am not necessarily looking for a car that is insanely fast like the RX7; this time around I want somthing that's simply fun & reliable.  I love the fact that the F20C revs to 9,000 RPM from the factory, is a total lightweight and gets good gas mileage... and that 6-speed is so smooth!  For now, I intend to stay N/A, but the project will have two phases the second of which will likely include a few lbs of boost.

 

I plan on doing a complete color change with the usual front lip, rear spoiler and fender flares.  The top contender right now is Toyota's "Anthracite".  I am not sure if I have ever seen a Zcar with this color, but I think it will look really good when it's all said and done.

 

Much, much more to come.

Edited by mattster03

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Sounds like a cool project. I'll be following along.

 

Have you considered a K20/24? It would have to be adapted to the trans, but IMO it has more potential (think >300hp). From what I've read, the F20c is pretty much at the limit from the factory.

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Sounds like a cool project. I'll be following along.

 

Have you considered a K20/24? It would have to be adapted to the trans, but IMO it has more potential (think >300hp). From what I've read, the F20c is pretty much at the limit from the factory.

 

I've had a few people ask me why not the K20/24.  I actually have never built a Honda engine before, meaning I am new to this world... so my reasoning might not be as sound as it should be.  I like the F series because it is a factory rear wheel drive engine and specifically designed for the 6-speed I really want to use.  I know people have successfully longitudinally mounted K-series and also mounted the F-series 6 speed to it... but it just seems like more work to me when I can get a full pullout and call it good.  There are plenty of guys running between 400-500 HP without problems on the stock block & bottom end, not to say that it's proper to do so....

Edited by mattster03

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Yeah, the K series will definitely take more work to get to the same place, so I can understand if you wouldn't want to deal with all that. But just to be clear, I meant >300hp N/A. No turbos involved. If you're going to boost it anyway, an F20c is fine, but I think the K series is the winner for all out N/A power, if you were going that route.

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Small update for the project... found an engine and transmission for sale and pulled the trigger this weekend.  The engine and trans is pulled from a '00 S2000, it's just about as complete as it can get.  Engine, 6sp, wiring harness, accessories, exhaust header, etc.  The only thing that it is missing is the PCM, but I plan on running an AEM EMS anyway.  I am not sure on the history of this pullout other than it was removed from a rearend collision car; I have inspected it fairly closely and a few things seem to suggest that the engine was boosted at one point in it's life.  You can see a little blue fitting on the front cover that I'm pretty sure is a cap to what used to be an oil return.  I'm a litte afraid that the engine has been abused a bit in it's past, but the deal was too good to pass up... $1700 for everything.  I normally see these go for $3K+ on ebay so I am pretty excited about that.

 

I am looking forward to starting to mock the engine up... some very very rough measurements seem to suggest that the engine will fit completely behind the front crossmember an the shifter should be centered in the tunnel +/- 1" or so.  The mounts might be a little interesting considering the engine is behind the factory engine mount points, but I design laser/brake parts all day at work so I do have a few ideas in mind.  More to come!

 

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Edited by mattster03

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Yeah, the K series will definitely take more work to get to the same place, so I can understand if you wouldn't want to deal with all that. But just to be clear, I meant >300hp N/A. No turbos involved. If you're going to boost it anyway, an F20c is fine, but I think the K series is the winner for all out N/A power, if you were going that route.

 

Ah yes, 300hp N/A is certainly the upper limit.  Honestly, I am really just looking for a fun car for right now and 200-220 hp to the rear wheels in this light of a car should be plenty fun.  My RX-7 was a real bruiser in terms of being terrifyingly fast and because of that I feel it lost a lot of driveability... I am ready for a fun car that I can feel confident about pushing the pedal to the floor whenever I want without having to think about what tires I have on that day haha

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I made some progress on the car this weekend, and with a day off tomorrow, I am hoping to get a full day of work in.  Started by pulling the old engine and transmission out; a load leveler is worth every penny!

 

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Here are the L26 and F20C side-by-side.  Quite a size difference, I hope to find a way to weigh them before this is all over, but I'm guessing right around 150lbs difference?

 

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Empty engine bay shot... lots of work to do here.

 

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MIght be a little soon, but I hoisted the F20 into place to at least verify it fits in the "envelope"... and I was quite happy to find that it is as good as a fit as I hoped.  The engine is completely behind the stock crossmember, the shifter is perfectly aligned with the hole in the transmission tunnel and it appears that the valve cover will clear the factory hood latch.  The one thing that won't work is the A/C compressor, it plows right into the steering shaft; but I really wasn't planning on running A/C anyway.  Still wondering if the stock header will fit.  Miles of space in front of the engine for future turbo goodies :).

 

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Here are the L26 and F20C side-by-side.  Quite a size difference, I hope to find a way to weigh them before this is all over, but I'm guessing right around 150lbs difference?

I'd love to know what the weight difference is. Also interested to see what your Z weighs when it's done!

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Spent my Memorial day morning working on the car again... everything was going great until I laid my head in a puddle of gear oil... can't stand that smell of that stuff so the day was over right about then LOL.  Anyway, made some more fine-tuned adjustments to the engine trying to get it in it's ideal location.  Here are a few more pictures of what could be close to it's final home:

 

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Frame rails are exactly 25" apart, so this is pretty well centered on the crank:
 

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Oil pan is just above the cross member (despite what the angle of the photograph seems to suggest)

 

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A close-up of the hood latch area.  The points of concern are the cam position sensor (cracked) and the oil cap.  Both are accessible:

IMG_20140526_123049_245_zps57daa78f.jpg

Edited by mattster03

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And now to discuss what I believe to be one of the more complicated portions of the project.  The engine mounts!

Traditionally, it seems most manufactures who make kits for the SR-20 / KA20 engine swaps (closest example I could find to the F20C since they are both 4cyl engine which mount far back) make weld in mounts which tie into the frame rails and pick up the engine mounts well behind the original chassis cross member mounts.  The reason for this, although obvious I want to state it, is because the whole engine is now behind the stock engine cradle mounting points, so therefor the engine mounts are going to be even further behind.  Here is an example of the most popular "Mckinney" KA-24 swap cradle:

 

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I'm am currently not a huge fan of this setup.  Probably mostly because I would rather have a bolt-in solution that uses the factory engine cradle.  From what I can see, the F20 must have engine mount points on the block which are further forward when comparing to the SR-20 / KA24 which gives me the idea that I might be able to design mounts that just "bridge" forward the required distance to pick up the stock engine cradle.... clear as mud, right?

So here are the measurements that I'll be working with for starters... I'll be making up some parts in 3D CAD to post up later this week to see what you all think.

Stock engine cradle angle... I'll assume it's 45*:

 

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The F20C engine comes from the factory in the S2000 mounted at a slight angle to help with hood clearance.  I am maintaining that angle which appears to be about 15* off vertical.

 

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And this is how far my replacement "bridge" mount will have to span... from the front bolt it's ~5-1/2 - 6".  No easy feat, but I do have a design in mind (sorry about the blurry picture, it was an awkward position and I was all hopped up on coffee):
 

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I have already posted this picture, but now you need to see it again to see the factory engine cradle mount points, the tilt of the engine and the aluminum mounts (which I will be re-designing/replacing):

 

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Is this making sense to anyone?  Hopefully my 3D CAD mock-up will better help relay my ideas...

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The mounts should be interesting and I'm excited to see what you come up with. When we did the SR in my car I went with the traditional cradle design McKinney had, but there are a lot of little things that could have been improved. One nice point of the cradle on rail design is that it allows you to move the engine mounts to whatever position you want (forward/backward) before locking them in place.

It looks like your placement of the F20c is almost exactly the same as the SRs (which would make sense because in general they are roughly the same size). We actually had to do some fab to let the oil pan pass through. When we did the first measurements it was with the stock pan, but swapped to a stainless custom pan that was a different shape right before final drop in.
 

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Love this build! I look forward to a final weight. 

 

The F20C seems like the ultimate out-of-box n/a 4 banger. There was an MKI Ford Escort competing in Targa Newfoundland last year powered by an F20C running through a Qauife sequential gearbox. Unfortunately I had to help the driver out after he rolled it into a telephone poll on a practice stage, but he had it back up and running for competition stages. I would have done horrible things to have that drivetrain setup.  

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The mounts should be interesting and I'm excited to see what you come up with. When we did the SR in my car I went with the traditional cradle design McKinney had, but there are a lot of little things that could have been improved. One nice point of the cradle on rail design is that it allows you to move the engine mounts to whatever position you want (forward/backward) before locking them in place.

 

It looks like your placement of the F20c is almost exactly the same as the SRs (which would make sense because in general they are roughly the same size). We actually had to do some fab to let the oil pan pass through. When we did the first measurements it was with the stock pan, but swapped to a stainless custom pan that was a different shape right before final drop in.

 

 

Thanks for the pictures... very helpful.  I think that the F20C mounts are about 1-2" further forward than SR's from what I have seen in pictures; tough to say for sure because it could also depend on how close you run the either engine to the firewall.  I may just end up doing the cradle setup, but I would like to try the bridge mount design for fun, I have a lot of manufacturing capabilities thanks to the place where I work (3D CAD, Laser, press brake, etc.).  I am very excited to get the engine and transmission all mounted up; that will be a great milestone in the project.

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Love this build! I look forward to a final weight. 

 

The F20C seems like the ultimate out-of-box n/a 4 banger. There was an MKI Ford Escort competing in Targa Newfoundland last year powered by an F20C running through a Qauife sequential gearbox. Unfortunately I had to help the driver out after he rolled it into a telephone poll on a practice stage, but he had it back up and running for competition stages. I would have done horrible things to have that drivetrain setup.  

 

Yes, I too think it might be the best N/A 4cyl out of the box.  I do think just from the inntial reactions from people outside this community that it is a little frowned upon to be putting 4cyl where 6cyl belongs and a Honda engine instead of a Nissan/Datsun, but I guess it is different and for me this project is all about the driveability and fun factor and you just cant beat that butter-smooth 6 speed and 9K redline when it comes to the F20C.

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Thanks for the pictures... very helpful.  I think that the F20C mounts are about 1-2" further forward than SR's from what I have seen in pictures; tough to say for sure because it could also depend on how close you run the either engine to the firewall.  I may just end up doing the cradle setup, but I would like to try the bridge mount design for fun, I have a lot of manufacturing capabilities thanks to the place where I work (3D CAD, Laser, press brake, etc.).  I am very excited to get the engine and transmission all mounted up; that will be a great milestone in the project.

 

It's always worth trying something new. No matter what design you do, with tools like that on hand you will be able to make a nicer unit than what you can buy off the shelf. Good luck!

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Here are the L26 and F20C side-by-side.  Quite a size difference, I hope to find a way to weigh them before this is all over, but I'm guessing right around 150lbs difference?

 

fwiw, if memory serves me correctly- Completely dressed L-series engines with transmissions weigh in just under 500 pounds (Give or take depending on the extra bits).  About 7X pounds and change for the transmissions, and about 42X pounds for the engine.  f20cs are about 460-470 pounds fully dressed with transmission.

 

Btw- LOVE this swap.  Ive actually got a kit to mount one of these in my 86 corolla.  Its been a dream engine of mine for a long, *long* time.  Im just waiting to pull the trigger on getting a engine.  My cars are stateside and I live in australia now, but i still get to them a few times a year.  Soon enough, hopefully.  Looking forward to the progress of this.

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fwiw, if memory serves me correctly- Completely dressed L-series engines with transmissions weigh in just under 500 pounds (Give or take depending on the extra bits).  About 7X pounds and change for the transmissions, and about 42X pounds for the engine.  f20cs are about 460-470 pounds fully dressed with transmission.

 

Btw- LOVE this swap.  Ive actually got a kit to mount one of these in my 86 corolla.  Its been a dream engine of mine for a long, *long* time.  Im just waiting to pull the trigger on getting a engine.  My cars are stateside and I live in australia now, but i still get to them a few times a year.  Soon enough, hopefully.  Looking forward to the progress of this.

 

Well that would be a bit dissapointing if there was only 30-40lbs difference...  I suppose the 6 speed vs. 4 speed is going to bring the weights of the two full pullouts a lot closer

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