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k24a2 swapped em1, motor has stock bottom end, k20a type R cams from japan, 50deg VTC gear, type S pump, supertech springs and retainers, rdx injectors, 70mm blox throttle body w/ ported and polished RBC, kpro, 3" exhaust with k tuned budget swap headers, dynojet tuned to 220whp. I was looking to get ~250whp from this build. is the header really cutting the flow that hard? would rather not buy a new one but I will if need be. any ideas as to why the power is lower than expected?





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97 civic HX K24a
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k24a2 swapped em1, motor has stock bottom end, k20a type R cams from japan, 50deg VTC gear, type S pump, supertech springs and retainers, rdx injectors, 70mm blox throttle body w/ ported and polished RBC, kpro, 3" exhaust with k tuned budget swap headers, dynojet tuned to 220whp. I was looking to get ~250whp from this build. is the header really cutting the flow that hard? would rather not buy a new one but I will if need be. any ideas as to why the power is lower than expected?





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The header is probably holding you back some, but 250whp is a lot of power from an all oem motor. I like the setup tho, nice parts combination. I have the same set of cams and vtc gear I have been thinking of putting into my k24a but was going to see how much I could make with the balance shaft pump and 25* gear.
 

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k24a2 swapped em1, motor has stock bottom end, k20a type R cams from japan, 50deg VTC gear, type S pump, supertech springs and retainers, rdx injectors, 70mm blox throttle body w/ ported and polished RBC, kpro, 3" exhaust with k tuned budget swap headers, dynojet tuned to 220whp. I was looking to get ~250whp from this build. is the header really cutting the flow that hard? would rather not buy a new one but I will if need be. any ideas as to why the power is lower than expected?





View attachment 103209
Maybe @LotusElise can chime in with some numbers 👍
 

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Arouse the DAMPFHAMMER!
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k24a2...stock bottom end, k20a type R cams from japan, 50deg VTC gear, type S pump...70mm blox throttle body w/ ported and polished RBC, kpro, 3" exhaust with k tuned budget swap headers...
Am I right assuming the head is a RBB casting?

Maybe @LotusElise can chime in with some numbers 👍
I would have a lot of questions first. RWD or FWD. If FWD what would help are: calibration and last dyno log. The engine is regarding peak torque a bit beyond it's potential, I need to see duty cycle, what fuel and ign. and VTC timing and so on. If RWD, wow not bad :D.
 

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Am I right assuming the head is a RBB casting?

I would have a lot of questions first. RWD or FWD. If FWD what would help are: calibration and last dyno log. The engine is regarding peak torque a bit beyond it's potential, I need to see duty cycle, what fuel and ign. and VTC timing and so on. If RWD, wow not bad :D.
It’s in a 99-00 civic si, FWD application
 

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I have an 07 k24a2 with similar setup revving to 8k and made about 230 whp on 91. I'm stoked with that. Not that it's not attainable, but a stock bottom end without head porting or aftermarket cams, 250 whp NA is going to be a hard goal to hit from what I've seen personally. Without head or block work I'm not even sure you'd be able to take advantage of a big tube header. Even then, 30 whp from just a header would be pretty amazing
 

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The engine is regarding peak torque a bit beyond it's potential, I need to see duty cycle, what fuel and ign. and VTC timing and so on. If RWD, wow not bad :D.
Why do you say in FWD configuration the engine is beyond it's torque potential? As a point of reference, I have a K24A2 out of a 2005 TSX with stock cams, 50deg VTC gear, type S pump, stock injectors, 70mm throttle body, stock RBB intake ported to throttle body, and PLM header feeding a 2.5" exhaust that puts down 200 whp and the same 177 wtq, not revving above stock 7,200 rpm redline.
 

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Arouse the DAMPFHAMMER!
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Why do you say in FWD configuration the engine is beyond it's torque potential? As a point of reference, I have a K24A2 out of a 2005 TSX with stock cams, 50deg VTC gear, type S pump, stock injectors, 70mm throttle body, stock RBB intake ported to throttle body, and PLM header feeding a 2.5" exhaust that puts down 200 whp and the same 177 wtq, not revving above stock 7,200 rpm redline.
VE is at about 116 %@around 5500 rpm, which is a good value. I've seen from OEM RBC IM with stock camshafts values of 120 % in the midrange, would be roughly 187 wftlb's at peak level. If I would know VTC WOT profile curve, ignition timing WOT curve and WOT duty cycle curve I could tell you more what would be needed to get there.
 

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Would you like to look at the .kal tune file? If yes, how do I send it to you? It does not look like the site will allow that file extension.
 

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Lets try this link and see if it works.
Did work fine :).

Ignition timing:
  • Part load way to retarded in low and high speed cam, part load mpg will be higher then necessary
  • WOT is a bit high for my experience after VTEC and ok in the high end
VTC:
  • Looks like the exhaust is giving the engine a drawback.
  • What don't align with that is the early VTEC of 3550 rpm at WOT. If the VTC above for high speed cam is the optimum, VTEC must be much later, thinking about 4000-5000 rpm
VTEC:
Without a log of WOT it is difficult to say if it is correct, just looks to early for me when comparing to VTC. Seems high speed lambda is more rich then the low speed lambda at WOT.

The engine definitely would be improved by an lower pressure drop in the exhaust, a bit more valve duration on at least intake side (the TSX cams would do a better job then the ITR's, even it is only slightly). Without fueling I can't comment on the lambda and finally about optimum VTC and VTEC.
 

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Arouse the DAMPFHAMMER!
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Here is the dyno printout to got with the tune.
Like I assumed to be, high speed cam is much more rich (up to 12.0:1 AFR vs lean 13.8:1 AFR before VTEC). I am not sure if this is from the car or dyno wideband. But it definitely feeds my assumption VTEC is too early.
 

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Like I assumed to be, high speed cam is much more rich (up to 12.0:1 AFR vs lean 13.8:1 AFR before VTEC). I am not sure if this is from the car or dyno wideband. But it definitely feeds my assumption VTEC is too early.
The graph you are looking at isn’t the OP, just FYI. I believe the graph posted is a 05 k24a2 with the original cams
 

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The graph you are looking at isn’t the OP, just FYI...
Yuup I know, it is this one

...As a point of reference, I have a K24A2 out of a 2005 TSX with stock cams, 50deg VTC gear, type S pump, stock injectors, 70mm throttle body, stock RBB intake ported to throttle body, and PLM header feeding a 2.5" exhaust that puts down 200 whp and the same 177 wtq, not revving above stock 7,200 rpm redline.
 

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Do you find it normal the torque is the same between the two setups, but the whp is 20 or so apart ? Is that all from one having 3” exhaust vs the 2.5 do you think ?
KBuilt, you have a good eye 🆙. When you check the cross points (5250 rpm for a ftlb-hp same scale diagram) you see there is something wrong in the OP's diagram. These engine setups have optimal VTEC, depending on exhaust and intake setup, between 4000-5000 rpm. OP's engine VTEC switch point is beyond that crossing point, despite the 50° VTC capability, which largely can lower VTEC switch point speed by advancing VTC. Either a failure in the diagram SW or a failure in the tune of the calibration.
 
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