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Discussion Starter · #1 ·
Hello everyone.
So, basicly im looking to build forced induction Frankenstein motor for my SW20 MR2. I aim to make 500bhp, which is reliable and with minimal boost. Im hoping i could achieve those powerlevels under 20psi, running E85

However, this is first time im doing a turbo build. Which is why Id ask for bit of help in part selection (other tips are appreciated too ofc). Even tho Ive been lurking the forums for ages at this point, there are still some things that are still bit unclear for me.

To The point.
Block: i am planning to use is Kmods K24 shortblock, that is bored to 2.5L. This comes with Manley turbo tuffs, tougher rod and mainbearings and wiseco Pistons. I plan to go with 10.1:11 compression (too high?) Block Also comes sleeved, which i know is not required for 500whp. I think that the sleeves bring Nice headroom tho, If i ever plan to push the engine for higher hp. Is this right, or are there some cons about the sleeves?

Heres The link for The short block :

Head: Just a stock refurbished K20A2 head. I am not planning to upgrade valves or springs. I am wondering If i should to?

Exhaust manifold i am planning to Fab up My self, most likely a sidewinder of somesort. Mostly because sidewinder manifold fits great in the engine Bay of The MR2, Also it gives advantage of very short ic piping. Still im littlebit unsure about that, as im not sure about The importance of the headers length. While theres advantage of all headers running straight before collector, the headers are far from equal length. Which leads me to question, would equal length manifold be a better option? (Im looking to minimize turbo lag, i still think log type manifold compromises toi much on Power side of things, so looking for some kind of middle ground)

Intercooler : This im not sure about, the size doesnt really matter as theres lot of Space in trunk of The mr2. Tought about getting long but thin ic. As this to my understanding would Be The most efficient. Ive read that the pte ic rated for 650hp would be a great option.

Turbo : i have heard good things about precision turbos, especially on The response side of things. Apparently those arent too laggy, which is one of The most important thing for me in this section. Thats why My first contender atm is Precision 5858. Im still on Bay about If i should get The journal bearing or ceramic bearing one. Or is there a better turbo option all together?

Intake : for The intake manifold i am planning to get a skunk2 ultra street. Then pair that with some 1000cc injectors. havent decided for The throttle body size just yet.

Well thats about it, some explanations mind sound stupid, sorry about that. Ill do My best to answer questions If there are any. Thanks for the tips on advantage! Ill keep updating the build on the forums after im done with the planning phase and get The build going
 

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at 500 wHp (some 650 cranki a RWD car you need to heavily invest in a gearbox upgrade such as PPG or gear-x and a limited slip diff. A few more grands in cost, but required.
A stock k-series gearbox will shred its gear teeth off first time you floor it at this power and torque level.
Everything past some 350 Nm (crank) needs attention and past 400Nm needs upgrades.
Never mind a sensibly sprung clutch and suitable hydraulic clutch actuation.

I don’t know if you have driven a 500 wHp turbo rwd car without ESP and traction control?
This engine will be a torque and power monster.
How wide are the tyres you intend to use? Beyond some 350 wHP, 225 section UHP tyres won’t have chance in life gripping at any normal road speeds in gear 1-4 (for 500wHp) at full chat. This is unless you like lighting up the rears in 4th gear at 160 km/h with 500 wHp. -> instant spin.
You will need to use boost by gear to not get into serious drivability issues.

May I suggest you consider sticking with some 350wHP to begin with?
This would allow to keep the stock gears and would work with a completely stock K24a2 or a3. No forged nothing. This essentially cuts your conversion costs at least in half.

What is your budget?

With build engine and transmission all in, you will have to spend some 15k in hardware alone for such a conversion.
I have converted three Lotus Elise to K-series Honda engines and have a rough idea on costs.
5-6k bare conversion not touching engine or gearbox, so straight out of donor car.
15-20k rebuilding it all and fixing up everything else you spot on the car while having an empty engine bay.
At these power levels you cannot afford any worn suspension or steering racks.

Mind you this was all DIY install.

fuel pump, fuel lines, oil lines, oil cooler, engine mounts, drive shafts, new CV joints, suitable wheel hubs, wheel bearings, suspension bushings, engine block, head work, gearbox refurb plus parts, ECU, conversion loom, exhaust manifold, decent turbo charger, heat management products,
 

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If there is a k-series gearbox adapter for the E153, I believe it is called mr2 Turbo gearbox, you would save a lot money.
The k24 itself can take a lot of boost without doing much except increasing the ring gaps a little. If the 500HP are only to be used for short squirts of power, that may all it takes.
What is your intended budget?
 

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@Lotus has an excellent point of starting with a smaller power level to shake the build out. The Kseries transmission was never designed for loads of TQ. That is meaning alot of the parts in the trans were not designed for loads of stress. If you take part the shift mechanism for example, like I just did I was very surprised how tiny things are.

My shift arm and interlock needed replacement. I am also replacing the shift lever because the shaft was dug into so bad from miss shifting from the previous owner. My transmission has never seen boost. I could count how many times it was miss shifted on the shift lever.
 

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Discussion Starter · #7 · (Edited)
If there is a k-series gearbox adapter for the E153, I believe it is called mr2 Turbo gearbox, you would save a lot money.
The k24 itself can take a lot of boost without doing much except increasing the ring gaps a little. If the 500HP are only to be used for short squirts of power, that may all it takes.
What is your intended budget?
I indeed own The E153 transmission, the one with tight LSD, And there is a adapter for k series.

I try to Make The build a reliable one, so i have quite high budget, around 12k$. For the engine, turbo setup, ecu etc that is. Work outside of tune i will be doing myself.

And i have driven an 300whp turbo silvia. Nothing like 500whp tho. But im not underestimating it. I think i know what im getting into. Id like ecu with The possibility of atleast two Maps tho. So i wouldnt need to ride with balls-to-the-wall 500whp all The time :D
 

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If you are not on the track using that percentage of the full 500whp is low. I get what your are saying though about having multiple maps. On previous set ups I had multiple maps for 93 octane, 103 octane, track tune and daily drive tune. Before going to the track I would set to track tune with race gas and do simulation driving to log information of how the engine and build was doing. I am glad I am past all that now and just want a simple set up that can be tracked as needed.
 

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from talking to chap in Austria, he runs a 500HP turbo K20 in a Lotus Exige, I’d stay away from 2618 pistons unless you like to swap them every two seasons.
Mahle forged pistons, I also got them now, are very nice and last longer due to the harder 4032 type of alloy they use. They are offered as a K24 version. The Cosworth offering uses the same forging. Cosworth is owned by Mahle these days. Coated pistons running only 40-60µm piston to wall clearance.
Get beefy forged steel rods.
For the sleeves I’d stay with 87mm to begin with allowing from several rebore shall the need arrive. This also allows you to use OEM head gaskets. Copper rings are likely not needed at the 1.3-1.5 bar of boost required for 500HP.
Use a hone brace and a (used) head gasket underneath it for boring the cylinders.
If you keeps revs below 7500 rpm, this k24 turbo will last a long time with proper mapping.
As revs are not high, you could fit Inconel exhaust valves . They are heavy, but can take the heat.
Cams, you can keep the stock ones. They work fine.

At 500wHp you might get into trouble with the big injectors that are needed for that power and passing emissions. You might have a chance with the injector dynamics offerings.
Do you intend to run e85?

You need charge cooling of a kind. Is this a mid engined MR2? It is usually difficult to run an air to air intercooler unless you are willing to lose the boot.
Water cooled charged coolers make this easer. You need at least 19mm water lines, better are even bigger ones, decent pump, minimum 2x Pierburg CWA50 or a single CWA100. Some even fit the CWA200. TinyCWA offer a controller. Or use your ECU to control the pump though LIN bus.
Try to fit as much pre radiator for the charge cooler to the front as you can. Under the main rad vented though the rad or through the floor and left and right. Drop any air oil coolers at the front (space for charge coolers) and cool the engine with a Laminova water / oil heat exchanger.

For a set of decent parameters to build the engine and the turbo manifold, I would suggest you get in touch with Markus aka @LotusElise and commission a set of simulations based on your ideas of power band and levels. He developed some sophisticated software tools for the Honda K-series.
He can give you a good idea on boost level requirements, manifold design, torque and power over rpm etc.
 

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Discussion Starter · #13 ·
from talking to chap in Austria, he runs a 500HP turbo K20 in a Lotus Exige, I’d stay away from 2618 pistons unless you like to swap them every two seasons.
Mahle forged pistons, I also got them now, are very nice and last longer due to the harder 4032 type of alloy they use.
Thanks for the tip, ill Look into it.

At 500wHp you might get into trouble with the big injectors that are needed for that power and passing emissions. You might have a chance with the injector dynamics offerings.
Do you intend to run e85?
Yes, i plan to run E85 with flexfuel setup.

You need charge cooling of a kind. Is this a mid engined MR2? It is usually difficult to run an air to air intercooler unless you are willing to lose the boot.
I plan to throw Air to Air intercooler Into the trunk, its going to be track priorised build, so i dont mind. I plan to fab a scoop of somekind under the trunk. Then ill make an aluminium enclosement around The intercooler, and make an outlet inbetween the rearlights. With this method i can also minimize The lenght of ic pipes. Also weight saving is something i Focus on this MR2. So thats partial reason why i wouldnt really like to use water to air ic

Kmod I heard all the bad things. You will end up having a kid before you get your block from them.
I dont really mind, i have plenty of bodywork etc to do on My project, its going to be a lenghty one.
(Except if they have like >1y queue :D)
 
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