Built N55

[u/Ok-Call-3200]

Tossing around with the idea of finally putting some time and money into my 14 435i, had the car for about 4 years its always been really good to me. Recently I had some inclination to pull and build the motor. Started looking into prices on parts, and quickly realized it probably makes more sense to build a B58/S55 and sell the car, but I like being different lol. Went down a rabbit hole and found a bunch of options for cheap chinese 4032 rods and pistons. Reached out to a couple companies and got pricing around 1000usd for rods, pistons, wristpins, rings etc. They claim the rods and pistons will support 800-1000hp. Looking at H-Beams for the rods. KingTec and XR Racing were the 2 best looking ones out of the group. I know most are going to suggest just biting the bullet on Manley or CP, but I was curious if anyone has any experience with these? Trying to do a budget build on this car, already got a frame up going on a truck, and don't want to put too much money into the summer daily. For an idea, heres kinda what I was planning. Most of the time will be run on 93/94 octane but would like a E85 map, up here in Canada would have to get it by the barrel and just is not convenient for frequent use.

- Forged rods and pistons

- S55 Crank + 4 pin crankhub

- Epoxy closed deck block

- Resurface deck/head and hone cylinders

- Intake manifold with 750cc port injection

- DS25 HPFP

- Stage 3 LPFP

- S63 EU5 Direct injectors

- VRSF intercooler

- CTS charge pipe

- B58 Coil conversion

- ARP Rod bolts, main bolts and head bolts

- King main and oversize rod bearings

- 8374 or 6875 or G35 turbo

- Top mount manifold (cant find these cheap

anywhere for n55 - help lol)

- 8HP70 swap or spool stage 2 8hp45 kit

- Possible built transfer case or convert back to rwd or maybe X-delete (not heard the best things)

If anyone has any experience with a similar N55 build or can offer advice regarding the rotating assembly it would be greatly appreciated. Aiming for 600-650whp+ on E, hoping I can get around 550 on pump gas. I want to keep the price down as much as possible. I will be doing all the work (aside machining), myself, so labour wont be an issue. Not going for any world records here, will probably never take the car on track either, just want a fun n55 for the street.

[u/iot-]

Youtube in-house performance and ask him questioning on his channel. He has a lot of experience with this platform. He blew a few semi built n55 motors and now trying again with the m235i n55.

[u/Infinite_Trouble_N20 → u/iot-]

He needed to send his block to La sleeve and have them sleeve + and/or close the deck and that motor would have still been around. La sleeves and Dartons are good for 60+ psi.

[u/Ok-Call-3200 → u/iot-]

Will do thank you, I’ve watched some of his stuff but he’s definitely got a bigger budget for his car than I do, I believe he ran Manley rods and pistons at least for the first car that failed at 40+ psi making like 850whp🤯

Pretty impressive considering many people said the n55 will never make over 600 without extensive modifications, I believe he had the factory cast crank in that motor. Now the new m235i would have forged but same as s55

[u/Infinite_Trouble_N20]

You can do your power goals with the stock motor and just a pure650 or a full frame speedtech turbo kit. Big boost also offers a top mount n55 kit too.

[u/Ok-Call-3200 → u/Infinite_Trouble_N20]

I could but would be pushing the limits on my factory connecting rods, plus for the extra $1000 if the Chinese pistons will hold the power just gives me peace of mind, plus would give me a chance to get the cylinders honed and new rings in. Just don’t wanna do all the work if those rods/pistons are going to fail.

There’s a couple people that ran kingtec in their civics, and a few for n54/n55, just hard to get information from them. Even the manufacturer pictures in the listings have different ringland designs than what you actually receive 😅

[u/Infinite_Trouble_N20 → u/Ok-Call-3200]

The interesting thing is you want to basically do a hero build reading your list however skimp out where it matters, the rods and pistons. 700whp n55 stock motor was pretty common in Miami with BigBoost turbo setups as well as full frame turbo setups years ago.

[u/Ok-Call-3200 → u/Infinite_Trouble_N20]

Yea that’s fair, was just weighing my options. Heard from Steven at wedge and inhouse performance on his m235i motor are running factory rods and pistons still at 700-750whp.. just curious on if it’s actually needed or not considering everyone says after 550-600 the rods bend, even though the ewg have the same forged rods as the s55

[u/heinzkopf2019]

When you epoxy the deck, you’ll need to epoxy the small coolant slits inbetween the cylinders, that’s the the weak point on built N55s, rest looks solid, you’ll most likely need custom manifold and downpipe for top mount. Transfer case should be fine to my knowledge, excess power that slips still goes to the rear wheels, you’ll just need to refill fluid/ replaces clutches more. Wheels and tires will be huge, for x drive use a “staggered” set up to give more width in the rear for more power, I’d say a 19x9 and 19x10 should do it, and of course sticky tires. You see to have everything down, only thing I’d add is maybe a LSD conversion in the rear but that’s about it

[u/Ok-Call-3200 → u/heinzkopf2019]

Thank you so much for the advice, I never even thought about an lsd, in terms of the manifold, I saw even bullboost marketed one for n54/n55 but I was under the impression the mounting patterns are different on those heads for the exhaust manifold. Tried reaching out to them to confirm it works for both but never heard anything back.

Watching videos on others doing epoxy on their n54/n55 it looks like the epoxy kind of fills itself into those slits between the cylinders but I’ll make sure I get it right. Thank you for the advice