3rd Gen GK Specific Fit Engine Modifications, Motor Swaps, ECU Tuning Sub-Forum Threads discussing engine mods/swaps/tuning for the third generation GK Honda Fit.

L15B1 Max Effort NA Engine Build Thread

  #1  
Old 04-15-2019, 05:43 PM
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Talking L15B1 Max Effort NA Engine Build Thread

I acquired a low mileage L15B1 engine from partsmarket.com. I am going to build a max effort NA motor. I am shooting for 200 crank HP. I'll provide updates and pics in this thread. The plan so far:

BLOCK
- Align hone and sleeve the block to 75mm bore. Should put the engine just under 1.6L.
- Knife edge the crank?
- Balancer shaft removal, if possible?
- Upgraded piston rods with ARP hardware
- Custom pistons 75mm 12.5:1 SCR
- Balance rotating assembly

HEAD
- Custom port and polish head
- 5-angle valve job
- Stage 3 Bisimoto cam profile ground onto my cams
- Upgraded valve springs to support increased lift
- Titanium retainers

TUNING
Ktuner V2
Church Automotive tune with Ktuner
Ktuner Flex Fuel Modification
Tune for 91 octane and tune for E85

I already have the catted RV6 downpipe and a short-ram intake. I have ported my intake, but I may consider someone more professional doing the same. I am about to port my throttle body. I am hoping to have this together and tuned by Christmas. Then I will just swap motors and tow her down to Church for tuning. Cheers! -d
 
  #2  
Old 04-16-2019, 12:11 AM
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Keep us posted! I've been contemplating on either upgrading my fit or getting rid of it. Would the head off of a L15B7 from a Civic SI benefit at all?

It doesn't make sense to build, but that makes it fun in of itself.
 
  #3  
Old 04-16-2019, 08:16 AM
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L15B7 head

That is interesting, but for this build, I want that sleeper, pop the hood, yeah that all looks stock vibe...
 
  #4  
Old Yesterday, 08:32 AM
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Very interesting, keep ppl in the loop ... This kind of na tuning is starting to become a lost art, but I think it is more interesting ...
 
  #5  
Old Yesterday, 08:35 AM
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Once you do this - will the car run safely (assuming very rough) on 87 octane? Just curious, I know the point here is optimize for 93 or maybe 91 is what's common there given your comment about the tune.
 
  #6  
Old Yesterday, 10:04 AM
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91 octane (r+m)/2

Fujisawa, I am already running exclusively 91 because the ktuner stage 1 tune is optimized for it. For the build, I want to be able to still run 91 but also E85 with the flex fuel sensor for racing. In Corvette v8 world, 13:1 SCR and above were reaching dangerous knock levels at 91 octane and below. That's why i am going with 12.5:1 pistons. Lots of people would run methanol or water injection also. You can fill up your washer fluid reservoir with meth and spray into your intake to reduce knock. Cheers!
 
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Old Yesterday, 03:56 PM
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Looking forward to see how this turns out.. Almost doubling the HP of an economy engine is cool stuff!!!
 
  #8  
Old Yesterday, 05:18 PM
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That's the Goal Nat (I'll show myself out of my own thread now)... Yeah, the Church guys said they don't think I can do it (of course GK Fit kids with stock motors are not knocking down their door to get tunes there), but if you search for LRPTEK or CarbonTek on this forum, or PPR Motorsports on Insta, you will see that people are reportedly making numbers. Are those numbers on a dyno that is running the SAE correction factor, or are people playing games? I don't know. Sure it's economy, but it's also dual overhead cam, direct injection, Honda that spins to 6750 stock from the factory. We will see. I got my quote for the bottom end. It is going to be way more $$$ than it's worth, but it will be pretty cool if I can pull it off. People told me to do a K-swap, but I will be very happy to have the motor that is supposed to be in there, with the factory wiring harness, etc, AC perfectly hooking up, no fabricating mounts. Whatevers...
BREAK BREAK
Last night I watched some videos of home head and intake manifold porting. Interestingly smoother is not better on the intake side for carbureted and standard fuel injection motors. This is because the smoothness can form fuel droplets on the runner. They leave it a little rough to ensure delivery of all the air-fuel mixture. So, I started thinking what about direct injection? Now you have only air coming in, but fuel goes direct to the combustion chamber, not the intake runner. Are cylinder head machinists modifying their port jobs accordingly? Then I saw an article about Katech doing porting on the LT1 and LT4 motors. Interestingly it said they are porting the intake and exhaust, but not the combustion chamber due to the direct injection (all it said). Again, I started to wonder if there is something there that needs to be accounted for. Usually you port the combustion chamber to a smooth finish to prevent detonation. If anyone has any S.A. on this topic feel free to chime in!
 
  #9  
Old Yesterday, 08:16 PM
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Hi! I wish you the most luck! Your plans for the bottom end are very promising!
I'll share the keys that we've found so far:
Cylinderhead- intake side has good geometry and a nice straight shot. Gotta open up a bit and eliminate the weird bowl lump.
-exhaust side is a mess and most of the time is spent opening up #1 and #4 runners radii.
-The exhaust valves are small. We sell larger valves (+2mm) that require new valve seats to be installed, an involved process to be sure but the stockers are VERY small. If you go this direction and put cams in, please mod the pistons to suit the increased exh valve diameter.

Intake- LRP tech carbon intake flowed more than enough from midrange and up. There isn't nearly enough meat on the plastic one to get the flow for your goals.
- Accord throttlebody 60mm matches the carbon intake well.
- stock airbox will become an issue( far too little) ... as will the airflow neck that the standard system gets it's readings from. It's less than 50mm.

As for dyno readings, you can check the correction factor for yourself on the sheet. LRP used 1.15 factor to estimating transmission losses to arrive at a supposed crankshaft hp readout.
We used 1.00 tcf which is hp at the hubs (hub dyno).

Good luck and post your progress!
 
  #10  
Old Yesterday, 11:15 PM
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CarbonTek, thank you so much for the very valuable and real-world information you provide through this website. I for one, learn from each of your posts! Apologies, I did not mean to imply there was any buffoonery on your part with the dyno numbers. I come from the corvette world where a lot of old men get their bravado from that sheet of paper and never put the power to use! I will be sure to pass on the cylinder head advice to the people I choose to machine the head. I am looking at Head Games from New Jersey. They do a lot of B, D, and K series work. I asked them about oversized valves and they said they usually get good gains going with the stock ones, but they also admitted they have no experience with the L15B1 and told me to get the parts and they would put it all together. I also worry about additional weight to the valve train of larger valves, especially with added lift of aggressive cams, and how to balance that with the correct spring pressure. As you know things get chaotic above 8,000 RPM. I wish there was a better following for this motor so I could be assured someone had put the valve components I choose on a spintron machine, etc.

Two questions: 1) do you smooth the intake runners on the head since it is direct injection? 2) Do you do anything to the combustion chamber as it is direct injection? Best regards, d'Art
 
  #11  
Old Today, 12:58 AM
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Originally Posted by Z062FIT View Post
I already have the catted RV6 downpipe and a short-ram intake. I have ported my intake, but I may consider someone more professional doing the same. I am about to port my throttle body. I am hoping to have this together and tuned by Christmas. Then I will just swap motors and tow her down to Church for tuning. Cheers! -d
I like you enthusiasm. Good luck on your build.
 
  #12  
Old Today, 07:18 AM
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Thanks Myx! Although I enjoy road racing, I want to pick up where you left off and continue to push LOL_FIT on the drag race side (I know his 700lb weight advantage will crush me). There's a few of us crazies here and it's great!
 
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