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Discussion Starter · #1 ·
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AB80

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If someone has a way to take the engine modifications and compute them into a reference suggestion that would be awesome. I want to see how it compares against the ITG's HP equivalent

I am using :
  • k20a2 PRB shortblock Mugen headgasket so (11.5)
  • 05-06 PRC intake cams
  • PNP RBC port matched to head & tb
  • cleaned up and minor shaping PRB-1 head
  • sanded smooth exhaust ports
  • cleaned valves
  • 70mm tb 74mm taper
  • 74mm ID x 86mm ID intake w/ velocity stack
  • SSR 4-2-1 header w/ megaphone
  • Kpro
  • RDXcc
  • AEM 340 lph

I do have the 04-05 K24a2 cams if I should mix the exhaust cam in. I think I need a different exhaust cam. better yet DC 2.2... or Toda something

AB80 Size Options

Part No.A (Length)B (Width)C (Inlet)D (Outlet ID / OD)BHP
AB80 w/ JC60/80C44324012080 / 83450
AB80 w/ JC60/86C44323812086 / 89480
AB80 w/ JC60/93C44323512093 / 96500
AB80 w/ JC60/99C44323512099 / 102520
AB80 w/ JC60/114C443230120114 / 117530
AB80 w/ JC60/124C443225120124 / 127

Measurements
A - (Length) Measurement taken from airbox inlet (C), to filter spinning outlet (D).
Rebated ARAB Spinning reduces length by approx. 20mm

B - (Width) Measurement taken at widest point of filter lid spinning.
Do not measure from screw to screw.

C - Inlet (Dirty air in) measurement taken as internal diameter.
See table for duct sizing guide.

D - Outlet (Clean air out)
All dimensions are in (mm)
 

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you‘ll end up with some 220 to 250 crank HP, so any of the listed are OK. They only deviate in their outlet diameter. I got the 78mm version rated for 310HP. There is virtually no pressure loss from these.
 

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Discussion Starter · #3 ·
you‘ll end up with some 220 to 250 crank HP, so any of the listed are OK. They only deviate in their outlet diameter. I got the 78mm version rated for 310HP. There is virtually no pressure loss from these.
thank Lotus for sharing your wisdom.

At some point I want to build a NA shortblock. This engine is being built for 9300rpm max reliable sprint rpm , 9000rpm redline shifting, and 8600rpm for DD redline.

* wet sleeve
*88-89mm bore
  • wide journal crank wide light rod
  • 82mm stroke. lightened, balance
  • 13.5 compression pistons
  • 4 Piston Oil pump
  • electric water pump
  • no AC

Re-do the head PRB-1 :

  • 3 angle valve job, new valve seats
  • True CNC intake valve bore +1mm intake port
  • True CNC exhaust bore 0.5mm exhaust port
  • Ferra 600 valve +1mm intake
  • Supertech + 0.5mm exhaust valve
  • Drag Cartel 2.2 cams
  • Supertech Beehive Valve Spring
  • Ti
  • Burns Stainless 2-1 collector to upgrade SSR header
 

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for these rpm, you can keep the 86mm stroke. Otherwise what your gain from rpm is lost though loss of displacement.
My engine is currently limited to 9100 rpm. I usually shift mid 8s on track. But one it while I let it fly. The supercharger makes them so rev happy.

Back to the ITG airbox. I had this side entrance ITG carbon airbox as they are commonly used on the S1 Lotus Elise. I kept it for the Honda conversions. Combined with a about 60cm intake pipe and the RRC (and RBC) intake, it created a horrible intake resonance at 4000 rpm and WOT. It was about as loud as a ship horn. Literally. On the high cam the sound was very ITB like.
In the S1 Elise they are normally used with a much longer intake pipe. The Rover also does not have such strong intake pulses as a K22 on Toda A3 cams.
I modified a Audi TDI intake Helmholz chamber and retuned it with a guitar tuner app to the right frequency and fitted it to the middle of the intake pipe. That worked rather well, bur was ugly.
I then got a straight ITG airbox that allowed my to use a shorter intake pipe. Press, the resonance was gone. The overall noise was also more sonoric and sounded less ITB like. Still better that the ship horn.

ITG carbon airbox with long intake pipe.



 
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