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Discussion Starter · #1 ·
Hi everyone, new to these forums but I've been lurking for some time gathering information.

As the title states, I'm working on putting together a K swap for my BRZ. The FA20 I have from factory just doesn't do it for me and boosting an already un-reliable engine doesn't seem reasonable.

A friend of mine has done this with his BRZ recently running a K24A2 with some eBay turbo and has yet to dyno but it seems to rip pretty nice and I'd like to do the same with mine.

Fitting the motor in the car should be no problem as KPower has done this and offers a pretty extensive parts list of adapters and what not. I plan to mate it to the OEM Subaru 6 speed for the time being and see how long that will take me.

My question for everyone here that I've yet to come across an answer to would be pertaining to the motor; it seems the de-facto "reliable" boost-build choice is a K24 bottom end with K20 head. My target for this build is 350-400whp on 93 pump gas. I'd also rather lower boost considering reliability in a daily driver.

If I can keep the motor as OE as possible and add bits and pieces to hit my power and reliability goals, that'd be great. Any suggestions on that front?
 

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Lotus Elise K20A2
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for a 350-400HP build there is no need to build a K20/K24 frank.
An run of the mill k24a2 or a3 will do.
if you are extra carefull, pull the pistons and increase the ring gaps.
 

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Discussion Starter · #3 ·
for a 350-400HP build there is no need to build a K20/K24 frank.
An run of the mill k24a2 or a3 will do.
if you are extra carefull, pull the pistons and increase the ring gaps.

Thanks for clearing that up. What have people pushed the K24A2 on boost to? Just want to make sure I have some headroom lol
 

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Discussion Starter · #6 ·
I ran 425whp ish before an overboost situation created a nice oil inspection port on both sides of my block.
That's good to know. I'm going to try and play it safe so sounds like 400 is reasonable for that.

That's super convenient! :LOL:

Will your stock transmission handle that much power? K series transmissions are usually good for around 400 whp. For 350-400 whp you'd be looking at around 10 psi.
From what I've read this car's transmission should be good up to about 380 ft-lb with an upgraded clutch, clutch fork and throw-out bearing.. not sure how true this is but there's a few 86 owners running the stock trans in that config with minimal issues. I guess no launches and I should be fine? :)
 

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Lotus Elise K20A2
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nice. You should try some semi slicks on track. You're all over the track squealing around.

RWD puts enormous loads on the GB due to weight transfer on acceleration.
FWD turbo builds get away with more power as acceleration actually lifts the front limiting transferred torque as the tires slip.


Worth watching Richard Holden's K24 videos. His other stuff is very nice, too.


He always increases the ring gaps on these turbo experiments. The rest is 100% stock. Otherwise he would break the ring lands on these cast pistons in no time as the ring ends butt.

He only stopped at 524 HP on the engine dyno as he was running out of injector flow.
 

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Discussion Starter · #9 ·
nice. You should try some semi slicks on track. You're all over the track squealing around.

RWD puts enormous loads on the GB due to weight transfer on acceleration.
FWD turbo builds get away with more power as acceleration actually lifts the front limiting transferred torque as the tires slip.


Worth watching Richard Holden's K24 videos. His other stuff is very nice, too.


He always increases the ring gaps on these turbo experiments. The rest is 100% stock. Otherwise he would break the ring lands on these cast pistons in no time as the ring ends butt.

He only stopped at 524 HP on the engine dyno as he was running out of injector flow.
Thanks for sharing this video it's actually fantastic for showing how little these engines need to get to some really solid numbers.
 

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nice. You should try some semi slicks on track. You're all over the track squealing around.
That was on a kart track, with street tires. I drove the car the six hours to run that event, so didn't have room to carry another set of wheels.


Normally, I run toyo RRs or something similar:
 
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