[robivtez]

This weekend I visited the dyno to do some dyno tunning for the first time by myself. But the results were not completely satisfying, so I thought I have to ask the best Honda forum about opinion and do some Brainstorming.

Setup is as followed:
K24A2, stock block and Head
regrinded OEM cams, lets say similar to DC Drop in Cams with 50°VTC gear
K20A2 double valve springs
K20A2 Oil Pump
RSP Ported Intake Manifold, 74 TB with 89mm Intake
R-Crew Replika Header, 200 Cell Cat, 70mm Exhaust

Tuned for around 12.8 AFR, under VTEC I have 30* VTC, on VTEC at the beginning 40*, at 6k rpm then falling to 30* at the limiter. Around 23-25* Ignition Timing, anything more, there was no gain at all.

Also, I wouldn't mind the 250 HP, but the torque is quite low, 250 Nm. At 4500 its making exacly the same torque as K24 from the factory, ~230Nm. The Torque looks like the typical modded K24 curve, just low numbers.

All the numbers are at the Crank, DIN Norm, it was around 25 °C, engine is healthy.

What do you think, could be low reading dyno, I am expecting too much? Was hoping for around 260 HP and at least 265 Nm.

Let the discussion begin.

 

[Them Witches]

I would not expect too much from basically a stock cam (regrind). The intake manifold you are running seems to produce well with the build. I am seeing 250HP right? that is not bad at all for a stock engine and DIC equivilents.

 

[Lotus]

a k24 needs more duration than a K20 for the same peak torque rpm and max power rpm and does not mind significantly increased lift figures as well.
Seems breathing limited.

A friend of mine did the same figures with a k20a2 stock block, RBC intake and Schrick cams. These are listed with figures (lift, duration) between Toda A2 and A3.
He got 243 HP and some 226 Nm of torque.

Your torque is there, but the power is missing.

High optimal VTC values near the rev limit would indicate breathing issues on the intake side. What lift and duration figures have these cams?

 

[20v_lover]

I always ask the guys what is your lash settings that you running with the OEM regrinds I don't believe in it BTW.
Your power seems right for the mods. Change your cam and what is the reason you running such low timing is the car knocking ?

 

[20v_lover]

a k24 needs more duration than a K20 for the same peak torque rpm and max power rpm and does not mind significantly increased lift figures as well.
Seems breathing limited.

A friend of mine did the same figures with a k20a2 stock block, RBC intake and Schrick cams. These are listed with figures (lift, duration) between Toda A2 and A3.
He got 243 HP and some 226 Nm of torque.

Your torque is there, but the power is missing.

High optimal VTC values near the rev limit would indicate breathing issues on the intake side. What lift and duration figures have these cams?

LOL they take stock cams remove lift and add duration. It is basically oem cams they regrind something that is often done in South Africa they make numbers
i think lol i personally never use them on any of my clients cars unless its done from billets.

 

[Lotus]

These Schrick cams, they are big in Germany for VW cams, were 2nd hand for cheap. But they performed really well and only got taken out due to fitment of a SC.



243HP and 226Nm, both crank ,is a decent number for a stock block K20 and pretty much drop in cams.

Schrick Cams vor Honda Civic Type R 2.0L iVTEC 4 Cyl. 4 Valve.

Intake: 232°/296°, Lift 7,33 (12,80), Valve lift at TDC 0,43, Lash 0,3
Exhaust: 236°/290°, Lift 6,81 (12,0), Valve lift at TDC 0,52, Lash 0,3

But we don't know what the OP's cams are, so litte point discussing Schrick cams. We don't even knock if the Schrick are bills or regrinds. Normally they would me marked as such.

 

[20v_lover]

These Schrick cams, they are big in Germany for VW cams, were 2nd hand for cheap. But they performed really well and only got taken out due to fitment of a SC.



243HP and 226Nm, both crank ,is a decent number for a stock block K20 and pretty much drop in cams.

Schrick Cams vor Honda Civic Type R 2.0L iVTEC 4 Cyl. 4 Valve.

Intake: 232°/296°, Lift 7,33 (12,80), Valve lift at TDC 0,43, Lash 0,3
Exhaust: 236°/290°, Lift 6,81 (12,0), Valve lift at TDC 0,52, Lash 0,3

But we don't know what the OP's cams are, so litte point discussing Schrick cams. We don't even knock if the Schrick are bills or regrinds. Normally they would me marked as such.

Yes but he went to take his oem K20 cams and have them cut LOL i must show you what it looks like. It boggles my mind that they fit these to their cars.

 

[20v_lover]

i refuse to fit these to cars i work on. Either way everyone is different.

 

[Them Witches]

i refuse to fit these to cars i work on. Either way everyone is different.

god no..

not in my house.

 

[Lotus]

I’ll ask to get some pictures of the Schrick cams.

 

[Them Witches]

I’ll ask to get some pictures of the Schrick cams.

I am not doubting your word that they work, just not for me. I get worried about micro pitting and fingernail ticks on the surface of a cam .

 

[Lotus]

I don't think the Schrick cams are regrinds.
This reference was more of a point that the OPs numbers are too low and it would be nice to get details about the cams he was using. We still don't know that.

 

[robivtez]

Hi,

Sorry for a late reply. My cams are from a Greek company, they are doing very good work, so I am not worried about the quality. In the picture are the specs of the cams. Keep in mind, that the duration numbers are at 1 mm opening.

Your torque is there, but the power is missing.

High optimal VTC values near the rev limit would indicate breathing issues on the intake side. What lift and duration figures do these cams have?

Well, I dont know, I would rather say, that the power is ok, but some of the torque in mid range is missing. The "breathing issue" is very likely the stock K24 head, I am sure, that I could gain some nice numbers with CNC ported head.

I always ask the guys what is your lash settings that you running with the OEM regrinds I don't believe in it BTW.
Your power seems right for the mods. Change your cam and what is the reason your running such low timing, is the car knocking ?

I set the valve lash according to OEM Honda specs.

About the timing, is it that low? What is the "typical" timing for such setup? I tried with 3 degrees more, then with 5 degrees more, and there was no noticeable gain, so I went back.

 

[Bjorn]

If you're not getting any more torque gains from ignition advance then you're right to leave it where it is. Ignition advance for the sake of it does not help anything. It just puts more heat into the engine.

 

[LotusElise]

Hello @robivtez, I miss the drag power line or was it a eddy current dyno? Somehow the drivetrain efficiency has to be measured, some information to that would be helpfully. BTW, the RSP IM is a very good choice, it never disappointed yet and has a nice potential and flexibility if clearance is not the challenge.

What does the term "healthy engine" mean in your view?

Around 23-25* Ignition Timing, anything more, there was no gain at all.

That's indeed interesting low for high speed cam. I've tuned K24A2 under the California sun on street and on dyno remotely with CR's from 10:1 to 12.5:1 and none of them were limited to less then 26° BTDC at 93 octane fuel (IM: RBC, RRC, S2 US and UR). May you share if it was knock limited or just by torque gradient? A information about the exhaust and header would be helpfully too.

In the picture are the specs of the cams. Keep in mind, that the duration numbers are at 1 mm opening.

Which picture? There is a dead link only. Could you please correct the link to that picture @robivtez?

 

[KBuilt]

i refuse to fit these to cars i work on. Either way everyone is different.

Oh no 😂

 

[LotusElise]

Oh no 😂

#me too. The smaller ground circle radius forces the valve shaft to expand the springs more and therefore the seat pressure get lowered. Without adapting the seat pressure spring force this can lead to power loss everywhere when the dancing of the valve at seat begins and can consequently damage the engine at serious situation like during of a bad shift event. The example of @20v_lover shows a guessed 1.5 mm smaller ground radius, which is a serious thing. According my spring layout calculation this would reduce max redline to 7800 rpm (coming from 9000 rpm) when 1.5 mm loss would be correct. Not everyone who follow such approaches may know what he is really doing there, like so often in the tuning and engine modification field.

 

[Lotus]

Good point Markus.
I had dbilas reground cams on my old Rover K a long time ago. But these engines use hydraulic tappets, so this additional spring extension does not happen.
Later for the VVC head, I got cams ground from billets.

 

[Them Witches]

#me too. The smaller ground circle radius forces the valve shaft to expand the springs more and therefore the seat pressure get lowered. Without adapting the seat pressure spring force this can lead to power loss everywhere when the dancing of the valve at seat begins and can consequently damage the engine at serious situation like during of a bad shift event. The example of @20v_lover shows a guessed 1.5 mm smaller ground radius, which is a serious thing. According my spring layout calculation this would reduce max redline to 7800 rpm (coming from 9000 rpm) when 1.5 mm loss would be correct. Not everyone who follow such approaches may know what he is really doing there, like so often in the tuning and engine modification field.

great explanation Markus. thank you

 

[Bjorn]

#me too. The smaller ground circle radius forces the valve shaft to expand the springs more and therefore the seat pressure get lowered. Without adapting the seat pressure spring force this can lead to power loss everywhere when the dancing of the valve at seat begins and can consequently damage the engine at serious situation like during of a bad shift event. The example of @20v_lover shows a guessed 1.5 mm smaller ground radius, which is a serious thing. According my spring layout calculation this would reduce max redline to 7800 rpm (coming from 9000 rpm) when 1.5 mm loss would be correct. Not everyone who follow such approaches may know what he is really doing there, like so often in the tuning and engine modification field.

I generally find your engine expertise to be far superior to anything i know but this time I'm not following your logic.

How can the cam base circle radius affect the valve spring seat preload? The seat pressure is purely a function of spring rate and valve install height. Grinding cams to a smaller base radius and adjusting the rocker screw adjusters to match doesn't affect the valve install height. The only spring i can understand having a change in operating parameters would be the lma spring that's under the high lobe rocker arm.
This raises an interesting issue with reground cams on a vtec engine, how does it affect the vtec rocket alignment for the locking pin engagement? Is the extra slack in the vtec rocker lost motion spring preventing the vtec rocker from staying in contact with the vtec lobe right up until vtec locks in?