Fuel pump hanger compatability between NA8 an NB
 

Yes, I have searched and I could not find a definitive answer to my specific question.

I am currently in the process of swapping an NA8 tank into my NA6 since my car has been sitting for a few years and I wanted a fresh(er) OEM tank I found used for a good price. The extra capacity is a bonus. Unfortunately(?) I ended up with an NB (BP4W) fuel pump hanger with a regulator on it. I am of the understanding that NB tanks are different but it looks to me that I can simply cut the portion with the regulator off and use it in my NA8 tank with a longer hose for the return. My question is about the float being compatible/ the correct length. Would I run into inaccurate fuel level issues if I were to use the NB hanger assembly in an NA8 tank? Everything else seems like it will bolt up just fine. I am going to make braided -6AN lines for the whole system for my N/A K24 swap, so I am not concerned about it matching the factory lines locations. I also understand that I could bend it but I am NOT a fan of bending float pickups. Any clarification or input would be appreciated.

I’m using an NB unit in an NA6 tank and it works fine. Mine reads a little optimistic during the first half of the tank, I think this is due to the tank volume differences. But NA8 to NB should be fine. The NA gauge reads the NB sender just fine.

Thank you for the response. My main concern was the flat bottoming out on the tank floor and not registering full correctly for a bit. I am also running an AEM CD5 so I realized this morning that I can just ohm out the empty resistance once installed and ohm full with the hanger out of the car and then adjust the values accordingly in the software. I was just overthinking everything the other night after a few "project inspirations".

To sidetrack my own thread, how have you found the 6 speed and 3.6 combo? I decided on a six speed and 4.1 OSG for mine base on local mountain roads and having shorter tracks locally.

I've enjoyed the 3.6, however I have a built engine that definitely makes a good bit more torque than a stock motor would, with ~95% of peak torque available from 3000-8000rpm. That said, when I built the car I had the elusive ideal-street-fun-car in mind that did everything well, so I wanted a respectable cruising rpm. Turns out the K24 swap is just a heinous NVH machine and only secondarily a great sports car. So between realizing its never really gonna be a comfy cruiser, and an accident that required lots of new sheet metal, it is on a rapid slide down the slippery slope to full track car. Accordingly, I'm probably gonna go to something a bit shorter in the coming year, but I'm not sure if I wanna go 3.9, 4.1, or even 4.3. I think 4.3 would probably be silly short, even with 9000rpm to play with, so been eyeing 3.9 versus 4.1. With how cheap the 4.1s are, I'm leaning that way as they seem to be the least desirable to most enthusiasts, but might be a happy medium for my use. I'm using MSM shafts and an S2000 torsen, but an OSG may be in the cards down the road.

I'm currently running 6sp/4.1 in my K powered track car. Engine is stock K24A/ 213whp. It's been pretty good for most AZ tracks, except Podium Club CCW, where the gearing was less than ideal. I'm seriously considering switching to a 5sp, especially since I've upped my tires to 245/40-15, which is slightly shorter than 224/45-15. Podium CCW is the most extreme example, but I was able to compare to a 5sp K swapped NB running similar lap times there, and he was shifting 4 times per lap to my 12. I do have a 3.6 diff I can try, and I may do that before ditching the 6sp. IMHO, 4.3 with a 6sp is way too much for a stockish K24... even with a high RPM engine, you'll be shifting constantly.

This makes me want to pull and sell my 6 speed and get a 5 speed. Thank you for your insight.

5spd wont survive with a K-swap unless its built. Local guy blew up like 3 in short order before he went to a 6spd.

6spd/3.6 combo is what I would do over 200whp. Hell I liked the 6spd/3.6 combo in my 135hp NB more than the 6spd/4.30 combo... it was faster. Went from being a 3rd/4th gear car with occasional 2nd and 5th to a 4th and 5th gear car with occasional 3rd and 6th. 3rd/4th/5th is overall better ratios than 4th/5th/6th...

Is this a sample of one? I haven't seen widespread reports of 5sp Miata transmissions failing behind stockish K24s, but I'll admit I haven't searched extensively. The HP/TQ is well within the 'accepted limits' for turbo BPs...?

And to continue the gearing threadjack, which I think is a pretty useful discussion...

I use Assetto Corsa and my SIM rig to do a fair bit of testing. I have built up a pretty good analogue of my real world K swap NA, and on tracks I've run real world, I've dialed it to the point where lap times are within .5-1 second. It helps me to get up to speed on new tracks, and test things like gearing. Long story short, I've done a bunch of testing that leads me to believe 6sp/3.63 is a pretty solid combo for a K swap car with a stockish motor. At most tracks, it's .5-1.0 seconds faster than 6sp/4.1, and it's generally easier to drive. Less shifting, and most shifts are 3-4, instead of 3-4-5. If I have more time this weekend, I'll try to spend some time on 5sp/4.1. I wasn't very impressed with 5sp/4.3 with the K.

Here's a couple of charts for 6sp/gearing with 245/40-15 (shift point is a conservative 7400 for reliability) :

https://live.staticflickr.com/65535/...5d378e74_c.jpg
https://live.staticflickr.com/65535/...98eac817_c.jpg

I agree it is a useful discussion. I may have to message the mods and ask if me derailing my own thread can be made into another one for more visibility. Thank you for graphing out the data as well. I have made the decision to go back to a 5 speed since I am stuck with a 4.1 that I had an OS Giken and new bearings put into. And the fact that my neighbor is going to buy my six speed made it a net profit solution for me. Looking at Kpowers geraing calculator, I am figuring that the additional torque of the extra .6l of displacement should cover the farther spread between gears well and still be very usable and enjoyable both on the street and track. I also have no worries about it not being able to hold the power of a stock K24Z3. Shock load is what kills transmissions and I understand mechanical empathy.

5sp/4.1 for 225 and 245 tires... I'd expect to be using 2nd, 3rd and 4th at most tracks.

https://live.staticflickr.com/65535/...830ac290_c.jpg
https://live.staticflickr.com/65535/...c1c6f849_c.jpg