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Discussion Starter #1
Hi there,

Im a old member here, this is my first post on this awesome engine forum.

There's overwhealming ammount of information here, and i might need some help composing a K20A with Rotrex C30 Build.

I want to know if a Supercharged K20A (JDM Storck internals) with a Rotrex C30 is durable (0.6bar/8.8PSI)

The power it produces is not WOW AWESOME, but its decent, arround 330hp at the crank, and arround 320NM/236LBS-FT's of tourque at 6800RPM.

I havent tested this setup yet, caus the project car is not any good to drive in deep snow. (Yeah, snowed in sort of normal here in Norway i live...)

But if i know myself right, i problably want more power and better tourque-curve on my next K20A Build, so hence my posting here:

What can i do to make my setup more durable, and perhaps get some more power out of it at the same time?

How mutch boost does a stock K20A handle? How mutch boost would you use, and if some parts is needed to to be excanged plase post it here.

I think ill start to build a New Engine in 2010, because i just like fideling with engines, i have pretty good mechanical skills, i can change more than my own sparkplugs.

And this new engine needs to fit where a K20A fits (same engine mounting points, and gearbox mounting)

So do one get more potensial by building a K24 (block) / K20 (head) hybrid? (im looking for pretty linear power delivery, and a max of 450hp at the wheels)

The car is a old Elise, witch used to have a rover engine in it, a trackday car.

I used to have a Motorsport Scholar Rover 1.8 16v, wich produced 226hp and arround 133lbs-ft (181NM) at 6700-8800RPM), But this was not a durable platform (like it blew up on me one day, leaving very little parts to salvage).
I'm completley new to K20A's and VTEC-system, so I'm very excited and eager to start composing a list of parts, and actions to do to them (sleeving the block, porting&polishing the head, etc...)

If i'we posted in the wrong part of this forum, just kick my thread back where it belongs. :)

Regards

Shadow_iX
"A small fat Norwegian guy with passion for motoring & speed"
 

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Well i the biggest thing i would be concerned with would be that high type-r compression ratio. but i would think what you are planning is do-able. i am thinking that you horsepower numbers your thinking might be low tho. I would love to help a lot more but my boost experience is with a roots type blower. My k20a3 in stock form at 8 psi form a jackson kit put down to the wheels 227, 168 tq. the rotrex kits are a totally different story.
 

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My K20A on a JRSC is handling 272whp 180wtq just fine at 6.5psi. This car is running at the track. So the abuse is high. Revving to 8800rpm constantly.

It's not always about boost on high compression motors. A friend with a K24A2 with JRSC is making 280whp 'ish at 9 - 10 psi, and not revving as high at 7800rpm. My K20a 272whp at 8800.

I am not a fan of building perfectly good OEM motors. A K20A with JRSC and W/I would be MY ideal way to go. Get a good OEM cam setup, and cool off the IAT with Alc/water and add density to the fuel. You can control knock and detonation with the W/I. Depending on what you use and what ratio. Meth/water or Alc/water.

I am told by my tuner the limit for stock rods and pins is about 300whp, in his opinion. I honestly don't want to find that limit. Happy building.

Christian
 

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My K20A on a JRSC is handling 272whp 180wtq just fine at 6.5psi. This car is running at the track. So the abuse is high. Revving to 8800rpm constantly.

It's not always about boost on high compression motors. A friend with a K24A2 with JRSC is making 280whp 'ish at 9 - 10 psi, and not revving as high at 7800rpm. My K20a 272whp at 8800.

I am not a fan of building perfectly good OEM motors. A K20A with JRSC and W/I would be MY ideal way to go. Get a good OEM cam setup, and cool off the IAT with Alc/water and add density to the fuel. You can control knock and detonation with the W/I. Depending on what you use and what ratio. Meth/water or Alc/water.

I am told by my tuner the limit for stock rods and pins is about 300whp, in his opinion. I honestly don't want to find that limit. Happy building.

Christian

Why use water/meth with the Rotorex? He might already have or can easily incorperate an intercooler and there is no need to use a water/meth mix to cool IAT...

If I was building a rotorex setup I would get some IPS SC cams, build a 10:1 bottom end with some light weight but strong parts, and turn up the boost...
Get some head work done at the same time and you can easily see 400hp+ at 16-18lbs...


just my 2 cents...

Rotorex > JRSC all day long! :wink:
 

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Why use water/meth with the Rotorex? He might already have or can easily incorperate an intercooler and there is no need to use a water/meth mix to cool IAT...

If I was building a rotorex setup I would get some IPS SC cams, build a 10:1 bottom end with some light weight but strong parts, and turn up the boost...
Get some head work done at the same time and you can easily see 400hp+ at 16-18lbs...


just my 2 cents...

Rotorex > JRSC all day long! :wink:
agreed. altought the part about JRSC lol, i like the power curve on it better.:p
 

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Hi there,

Im a old member here, this is my first post on this awesome engine forum.

There's overwhealming ammount of information here, and i might need some help composing a K20A with Rotrex C30 Build.

I want to know if a Supercharged K20A (JDM Storck internals) with a Rotrex C30 is durable (0.6bar/8.8PSI)

The power it produces is not WOW AWESOME, but its decent, arround 330hp at the crank, and arround 320NM/236LBS-FT's of tourque at 6800RPM.
I'm not sure where those numbers come/came from but they are quite different then mine.

325-330Hp and 209-210 lbs ft @ 8200 rpm 7.1 psi on a completely stock K20A2 (Dynojet 224xLC)
 

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Discussion Starter #8
My numbers are estimates for now, the same parts and tubing(incl. Exhaust) are in another car, i'll get the same map too, and the other guy got 332hp/238lbs-ft at 8psi.

So i estimate allmost the same for myself, when the snow melts here ill go to my dealer to rent his dyno packs to help map the car properly.

PS: Its mutch snow here theese days, and more will come... (current snow deapth is allmost 5feet. - This is all that's keeping me back at the moment.)
 

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Something is still wrong with those numbers... unless I missed something your 2.0L wont make 235-240 lb. ft. if your only making enough boost to make 330HP
 

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I'm considering a Kraftwerks kit for my EG road race/time attack car and have done a lot of research on them, including a few hours on the phone and many e-mails with Oscar Jackson. Here's some of what I've learned.

Rotrex sc's like compression. Remember, the Kraftwerks S2000 kits, which make really impressive power at 11psi, does so on a 11:1 compression engine and does it with total reliability on 91 octane pump gas thanks to the high quality coolers and belt tensioning system they've engineered into their kits. So don't be afraid of compression. Like any forced induction system, good ECU tuning is critical, so make sure you've got good control of fuel and ignition timing and run a fairly high octane fuel and you should be golden.

It's also important to keep in mind that a Rotrex builds boost in a linear way (builds boost with RPM, since it's linked to the crankshaft), so you don't get the big boost spikes associated with a turbo. This means there's far less shock put into the engine and the drivetrain components, meaning you don't have to over-build the engine the way a lot of turbo guys are used to having to do. So when you hear that a K20's rods are only good to 300whp or so, that's not necessarily the case with a Rotrex. In Oscar's words, “The problem with turbo-related heat buildup and the fact that the turbo spools so rapidly at mid rpm levels without being controlled by the crankshaft is that ECU tuners are forced to throw a ton of fuel into the combustion chamber and pull timing at the point of full spool to protect against detonation. With a Rotrex supercharger you can actually do the exact opposite, leaning out the a/f ratio and adding timing because the system runs so cool. As a result, you end up with improved fuel efficiency and more consistent and reliable power production.”

It's also worth noting that since Rotrex's are sealed units that have their own separate oiling system, so there’s no need to tap the engine’s oil pan. This also means that, unlike a turbocharger and some sc setups, the Rotrex blower doesn’t tax the engine’s existing cooling and oiling systems, helping keep under-hood and engine operating temperature under control. So again, less stress on the engine and drivetrain components and more durability/reliability than you might expected with a forced induction setup.

Anyway, IMO you should be able to safely run 10psi on your stock K20A since that's what the Kraftwerks S2000 high boost kit runs at. But to ensure reliability, you need a good programmable ECU, high quality fuel, and an efficient oil cooler for the engine, plus Kraftwerks recommends going one step cooler on the spark plugs. You'll also need larger fuel injectors. 650cc is recommended, and a fuel pump that can flow enough juice too.

If you decide to build another motor for your Elise and a K24 will fit (they're a bit taller than K20's), then obviously you'll get more torque at lower revs with the larger displacement engine, but these blocks don't like high RPM quite as much (longer stroke/higher piston speeds mean you really shouldn't push them past 8k rpm max if you want any kind of longevity out of them). My K24A2 (TSX/Euro Accord, 10.5:1 compresion ratio) block with Skunk2 Stage 3 cams and the usual bolt-ons makes 250whp on pump gas (I limit it to 7500 rpm for reliability). With a the C30 Rotrex at 10-11psi I'm hoping it'll make 400whp on race gas, which should be feasible given what the Kraftwerks S2000 high boost kit w/ C30 makes 365whp on pump gas.

Good luck and let us know how your project goes! I've been dreaming of a K24 Lotus Elise track car myself, so I'll enjoy living vicariously through yours. Post some pics! :)
 

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10 psi on a stock engine is about the limit before mods, e.g., rings, are required to preserve reliability. I am making 353 whp and 225 wtq with a 110 mm s/c pulley (C30-94) and a 152 mm crank pulley at a conservative 8,300 rpm redline on a Euro K20A2 with meth/water injection. I will be switching to the JDM 130 mm crank pulley and 95 mm s/c pulley soon preserving my current overdrive ratio/boost level. With less mass to turn, the engine should be more eager to rev with the smaller JDM pulley.
 

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I'm considering a Kraftwerks kit for my EG road race/time attack car and have done a lot of research on them, including a few hours on the phone and many e-mails with Oscar Jackson. Here's some of what I've learned.

Rotrex sc's like compression. Remember, the Kraftwerks S2000 kits, which make really impressive power at 11psi, does so on a 11:1 compression engine and does it with total reliability on 91 octane pump gas thanks to the high quality coolers and belt tensioning system they've engineered into their kits. So don't be afraid of compression. Like any forced induction system, good ECU tuning is critical, so make sure you've got good control of fuel and ignition timing and run a fairly high octane fuel and you should be golden.

It's also important to keep in mind that a Rotrex builds boost in a linear way (builds boost with RPM, since it's linked to the crankshaft), so you don't get the big boost spikes associated with a turbo. This means there's far less shock put into the engine and the drivetrain components, meaning you don't have to over-build the engine the way a lot of turbo guys are used to having to do. So when you hear that a K20's rods are only good to 300whp or so, that's not necessarily the case with a Rotrex. In Oscar's words, “The problem with turbo-related heat buildup and the fact that the turbo spools so rapidly at mid rpm levels without being controlled by the crankshaft is that ECU tuners are forced to throw a ton of fuel into the combustion chamber and pull timing at the point of full spool to protect against detonation. With a Rotrex supercharger you can actually do the exact opposite, leaning out the a/f ratio and adding timing because the system runs so cool. As a result, you end up with improved fuel efficiency and more consistent and reliable power production.”

It's also worth noting that since Rotrex's are sealed units that have their own separate oiling system, so there’s no need to tap the engine’s oil pan. This also means that, unlike a turbocharger and some sc setups, the Rotrex blower doesn’t tax the engine’s existing cooling and oiling systems, helping keep under-hood and engine operating temperature under control. So again, less stress on the engine and drivetrain components and more durability/reliability than you might expected with a forced induction setup.

Anyway, IMO you should be able to safely run 10psi on your stock K20A since that's what the Kraftwerks S2000 high boost kit runs at. But to ensure reliability, you need a good programmable ECU, high quality fuel, and an efficient oil cooler for the engine, plus Kraftwerks recommends going one step cooler on the spark plugs. You'll also need larger fuel injectors. 650cc is recommended, and a fuel pump that can flow enough juice too.

If you decide to build another motor for your Elise and a K24 will fit (they're a bit taller than K20's), then obviously you'll get more torque at lower revs with the larger displacement engine, but these blocks don't like high RPM quite as much (longer stroke/higher piston speeds mean you really shouldn't push them past 8k rpm max if you want any kind of longevity out of them). My K24A2 (TSX/Euro Accord, 10.5:1 compresion ratio) block with Skunk2 Stage 3 cams and the usual bolt-ons makes 250whp on pump gas (I limit it to 7500 rpm for reliability). With a the C30 Rotrex at 10-11psi I'm hoping it'll make 400whp on race gas, which should be feasible given what the Kraftwerks S2000 high boost kit w/ C30 makes 365whp on pump gas.

Good luck and let us know how your project goes! I've been dreaming of a K24 Lotus Elise track car myself, so I'll enjoy living vicariously through yours. Post some pics! :)
If this is all true, the Rotrex is what I am going with on my K24a2!
Good stuff!
 

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The entire automotive enthusiast communnity is largely behind the times and in the dark when it comes to the Rotrex Supercharger and what it is really capable of. How few people must really go out and educate themselves on a given subject.

Every person that argues the impossibility of this or that from a Rotrex hasn't called up the guy who is actually doing it and gone over dyno charts. After researching these superchargers for a couple of months and wondering why people take so long to accept new ideas, technology, or truth... I just chalked it up to human nature.

It doesn't matter if there is one true religion, an ultimate creed, a clearly superior technology, or whatever, people will still refute it, ridicule it, and only accept it when "everyone else is doing it".... if then.

sigh

The Rotrex Supercharger killed Turbocharging, what, a year or two ago? It just takes a long time in this instance for all the bodies to hit the floor.
 

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The Rotrex Supercharger killed Turbocharging, what, a year or two ago? It just takes a long time in this instance for all the bodies to hit the floor.
I love it... Just call it how you see it!

I see a Rotorex in my future :up:
 

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Discussion Starter #16 (Edited)
Just throwing out some pictures of my setup.





and something else i think is kinds cool, datalogger.



The car is getting a dynosession soon, I'll know more then. :)

PS: i may have posted theese pictures before, i dont quite remember, my memory is kinda fuzzy from all the fumes man..
 

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Beautiful setup, Shadow_iX! That is the "correct" engine that Lotus should have used all along :) Honda power in one of the best engineered mid-engine sports car of all-time is the ultimate combo. Only way to make it better is by adding a Rotrex, the ultimate in efficient forced induction. Keep us posted the dyno results! :up:

BTW, looks like there's plenty of room to fit a K24 under the bonnet, so if you wear out your K20, stepping up to the "big block" might just be the way to go. Fewer revs means less stress on the engine and blower, and the torque would really pay big dividends coming out of tighter turns. Just hope you can squeeze a lot of rear tire under it to put the power down :)
 

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Discussion Starter #20
I have no idea, ill look into it at a later time. perhpas its the rotrex's max rpm reached or something. :)

It might be the rear muffler that's too stuffy... Its changed now, and i think this will improve the curve @7k rpm a bit...
 
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