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Arouse the DAMPFHAMMER!
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My CR in that camber would be at 13s:1. IM is stock jdm k20a rrc. CAI is hybrid racing.
Thanks for sharing.

H? What does it mean?
Sorry, I am using too much acronyms here. It means header.

To summarize your engine setup:
  • small block:
    • 86.5x86 forged pistons from supertech
    • combustion chamber has a CR of 13:1
  • head:
    • stock valve seats
    • 35/30 mm valve size
    • valve seat lapped at valve
    • port flow not tested, but estimated at 350 cfm/230 cfm on unknown valve lift
    • stock cams
  • Induction:
    • RRC IM
    • CAI from HybridRacing
  • Exhaust:
    • unknown header
    • unknown muffler
    • unknown exhaust pipe diameter
    • resonator also not known
  • fuel: unknown
Knowing more about the Exhaust: header, CAT, pipe diameter, resonator and muffler would be great.

You can run a 13:1 CR on 94 octane fuel knock free at ign. timings of 29°-31° if the exhaust setup is done right and the cams are the right choice for the application and CR. The stock cams a certainly not those, as dynamic compression get's pretty high. If you need help with the tuning, let us know here.
 

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Discussion Starter · #23 ·
Thanks lotus Elise for summing up.

Exhaust:
    • unknown header - stock jdm k20a (due to street legal reasons) but catless catalytic converter
    • unknown muffler - spoon n1 catback (due to street legal reasons)
    • unknown exhaust pipe diameter - should be 65mm if I’m wrong
    • resonator also not known - spoon
  • fuel: - 98 ron
Definitely after some help and advise from friends and other tuners, they felt my current tune ign timing is advanced too much hence the knock is still present once I go into vtec 5k rpm onwards. And the natural reaction was looking to retard timing where the knock start to occurs.
For the cams between the dc 2.2 and 3.2 which would u suggest to use for some occasional track days but daily driven. Stock cams are great but I feel it starts to lose out from mid to top end power.
P.S: i am on short gear ratio on 4,5&6
 

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Arouse the DAMPFHAMMER!
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8,706 Posts
Yesterday I wrote with an guy who design parts like cams, headers, head ports and so on for some racing series here in Europe. He told me about having a torque dip around 4500 rpm, I asked for the dyno sheet, got it, went into my header calculation with the dyno sheet information and came back with an header design which he was building and why a dip must be at 4500 rpm. He was surprised about the exact calculation result which was within 20 mm to the real header lengths. Header design is very simple, if one knows the background.

I am sorry to say, for your setup, I am 85 % convinced according to my calculations, it won't work well, except around it's only supporter engine speed, which should be around 6100-6800 rpm (not sure about the exact primary length of the shortest available 4-1 header in the K-series world), next to the resonator point of the alternation of load system with the RRC. On all other engine speeds this setup can't deal with a 13.0:1 CR, as it has too much residual gas available in the combustion chamber. The maybe better VE by the head plus the higher compression ratio in combination with this header cause a lot of knock issues: residual gas content way over 2 %, higher temperatures due to the high CR, higher pressure due to the better flowing head is a very bad combination and increases the knock capability massively. The lost of torque due to the amount of ign. retard, because of knock, is much bigger then the amount of torque you win by a 13.0:1 CR on just 98 RON fuel.

If you can't run another but well designed header between emission test events because control is frequently and straight then swap this piston out for a max. 11.5:1 piston and max. TODA A2 or DC DIC cams, which will give you much more torque and fun also in summer when ambient temperatures rises. Your engine builder should know it better and always look an the full picture. A NA engine is very sensitive to the alternation of load parts. If the header is not willingly to support that setup, then none of the other techniques and improvements will work as it could. NONE. Your engine builder should know this. Now you have invested a lot in the head port work and pistons, which even increases the issue.

If I am right and you are from Singapore then I know your head builder, as I there is only one CNC head in your area doing K-series heads like this. He is also a Drag Cartel parts dealer. If so, I will have a word with him.
 

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Discussion Starter · #25 ·
hi lotus Elise, your analysis is quite true and interesting and very informative to detail. I’m learning through your analysis as well.
Well yes I’m from Singapore. The DC dealer you mention here yes and I have seek his advise and services so it’s ok no need to go speak to him as I don’t wish to blow this up big. I just like to understand and learn more from people here using this chat from their experience.
 

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Arouse the DAMPFHAMMER!
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8,706 Posts
hi lotus Elise, your analysis is quite true and interesting and very informative to detail. I’m learning through your analysis as well.
Thanks man.

Well yes I’m from Singapore.
Now I am in the full picture about the summer requirements and...

The DC dealer you mention here yes and I have seek his advise and services so it’s ok no need to go speak to him as I don’t wish to blow this up big. I just like to understand and learn more from people here using this chat from their experience.
...and I know which Tuner we are talking about. I had some race and street car remote tuning projects in Singapore before I get to know him. Say greetings to Fabian from me.
 

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2002 DC5 Type S
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Would you know it Markus, I have been to Singapore. In 1994 I was there for a week in the Omni of Singapore right across the street from the jail the guy from the US that was caned for spray painting cars. That is one clean place and they do not play with littering of bubblegum on the sidewalk $500 fine. Death penalty for drugs. Downtown on the main strip, or drap, or avenue, there are cleared properties for sale with signs in posted "do not trespass or will be shot."

Back in 1994, it was expensive to have a Honda over there. Something in the range of $250,000 in their currency.
 

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Arouse the DAMPFHAMMER!
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8,706 Posts
Would you know it Markus, I have been to Singapore
Nice. I have some friends there. I know only from friendly and kind people from there. They have a nice K-series scene and I pull my hat off for the challenges they take to get nice builds. Beside the climate, way too hot and too humid for a mountain guy, the resources are not as well spread like as here in Europe. Therefore I help out with locally affordable remote tuning and engine setup development support.

Fabian, the tuner of @tarmacfd2r engine, is one of the few tuner in that area. I saw some of his calibrations and engine built's, which was solid stuff. Those tuners of that level are rare in Singapore, as well fair is increasing fast and demand is increasing. Side note, if you know the British East-Indien-Trading Company, the base structure for todays well fair was set there by them in the early 19th century. The economy system is still based on those experiences, it is one of most free and most competitive market places of the world. The actual Euro 3, 4 and 5 engines are the main tuning objects, but they also have a restrictive emission handling, similar to our requirements like here in Europe. Regular emission tests are mandatory and fines are high, e.g. non-traffic related idling can be fined up to 5000 SD, here in Germany you may get a up to 3 digit fine if one set a file against you. So this place is a challenging place for an average tuner of an non-emission related background, one have to know his stuff.
 
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