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Arouse the DAMPFHAMMER!
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...BC recommended no more than 40°. I clayed the motor and it can go to 40°...
How much PtV clearance was left at 40° VTC?

...Will it be safe to rev the car to 8500 or is that pushing it :) Forgot to mention i have the RRC oil pump as well.
Definitely not safe for an WW, the stock pistons will began to rehone the liners if lambda is not adjusted right WOT and high engine speeds. The K24A3 has a piston cooling via oil squirter, but the time to cool them down is too low for that small piston to liner clearance. And if you run lower WOT lambda's for more cooling, it can dilute the oil with fuel if oil change interval is not adapted according the application needs. Therefore the lambda window get pretty tight...nothing for a Honda stock ECU. I wouldn't increase engine speed beyond 7800 rpm with those pistons. From an oil pump and valvetrain view it isn't a problem, just piston seizure creates a risk.

I was DD driving stock pistons well to 8800 rpm and they came out well. But the WOT content is soooo low, longest was an around 5 min WOT at the Autobahn with 260 km/h. If you run it on long term WOT sections with some decent shifts and transitions the storyline for the liners and piston is different and only like that, it is a risk. The skirt forces increase massively at 8500 rpm with an 99 mm stroke engine, so the burden to the tribologic of the piston-liner-oil-system is significant increased compared to an 86 mm stroke engine.
 

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How much PtV clearance was left at 40° VTC?

Unfortunately i didn't measure the thickness of the clay at it's thinnest point after cutting through it. I just remember it being enough seeing that i was only going to run it at 35°.

Thinking about it now if the tructuff pin of 35° is only giving me 32° 33° i wont be surprised if the 40° one only gave me 38 while checking p2v

I did however increase the valve radius clearance slightly.

Definitely not safe for an WW, the stock pistons will began to rehone the liners if lambda is not adjusted right WOT and high engine speeds. The K24A3 has a piston cooling via oil squirter, but the time to cool them down is too low for that small piston to liner clearance. And if you run lower WOT lambda's for more cooling, it can dilute the oil with fuel if oil change interval is not adapted according the application needs. Therefore the lambda window get pretty tight...nothing for a Honda stock ECU. I wouldn't increase engine speed beyond 7800 rpm with those pistons. From an oil pump and valvetrain view it isn't a problem, just piston seizure creates a risk.

I was DD driving stock pistons well to 8800 rpm and they came out well. But the WOT content is soooo low, longest was an around 5 min WOT at the Autobahn with 260 km/h. If you run it on long term WOT sections with some decent shifts and transitions the storyline for the liners and piston is different and only like that, it is a risk. The skirt forces increase massively at 8500 rpm with an 99 mm stroke engine, so the burden to the tribologic of the piston-liner-oil-system is significant increased compared to an 86 mm stroke engine.

Ok i understand but in my case iam only using it as fun on a Saturday on the drag strip. Yes i know iam not going to be breaking any records out there but i will be enjoying myself :). I am currently revving the car to 8300 atm and just for that one hit at a time. I have been using a slightly richer AF ratio ontop. I will just have todo earlier oil changes.
:hi:
 

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Arouse the DAMPFHAMMER!
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5,684 Posts
Thinking about it now if the tructuff pin of 35° is only giving me 32° 33° i wont be surprised if the 40° one only gave me 38 while checking p2v
Wow, that's a good information. Maybe they added tolerance for safety?! Makes me thinking of doing an RBB cam gear machining to 40°...

...I am currently revving the car to 8300 atm and just for that one hit at a time. I have been using a slightly richer AF ratio ontop. I will just have todo earlier oil changes.
If it is only for short, which means just for shifting (= less than 2 s), and you reduce the oil change interval radically you could increase it to 8500 rpm, but this is no guarantee. This area pushes so much load on the tribological system that individual factors (oil type and temperature, squirter efficiency and spray direction, fuel distribution, ...) could kick the system from the edge of safety in just a few rotations of the crankshaft. Keep two things in mind:
  • cycle fatigue is related to load (forces, temperatures) and time, so you can just choose one of them if you don't adapt the system itself.
  • wear may has an linear coherence between load and time where it is designed for, but there is a strong non-linear coherence at the limits
:twocents:
 

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You are the first one measuring the low speed cams :wink:. Sorry for my wrong assumption.

Normally the high speed lobs are the one you want to know the piston to valve and valve to valve clearance, as these should be the only one touching the piston or the exhaust valves, otherwise I would assume a NON-VTEC setup or a too huge low speed cam which likely need an increased idle speed of more than 1200 rpm.

Thanks

This explains much. For a non cam phasing setup you need to adjust for an compromise, not to much advanced, but also not retarded for max power only, just like that so you find the best powerband you need. Advancing support always the left to mid side of the engine speed band of that cam (here high speed powerband). In your case of having a pure high power camshaft you need to think about more retard and to increase your engine speed. Like drmo already stated, this is a 273°@1 mm lift cam, which is for 86 mm stroke a pretty looooong duration. For a 11.500 rpm 78.5 mm stroke engine you don't need to go over 265°@1 mm with the right induction and header design, just for your comparison.

I would also agree with you, I also wanted to wait for further information, especially the ignition data could tell us more about a VE or combustion related issue. But my feeling is also more into VE direction, just because of the duration, which need an awesome induction and piston speed to get this chab running.

Sorry for late response. But at it again. I had nothing todo with intake manifolds and exhaust system. 2 other companys custom built that. The pipes are 50.2mm outside and probably around 46-48mm inside (dont know the thickness) 750mm until it goes to 4-2 and than 1. 3" system the whole way and race cat and the end bumper (as regulation says you have to have it in rally).

The intake are 51mm tapered jenvey throttles
https://store.jenvey.co.uk/throttle-body-kits/honda/honda-k20-ep3-sf51-taper-kit-ckha07-kit

Ign between 27-33degree I dont have the ign table at hand now. But its tweaked for every cam adjustment to find more.

I'm going to test milder cams now Group-N rally cams. they are quite much milder, between 245-255degrees at 1mm have no exacly cam spec on them.

I hope I can atleast find some hp here to be abel to point the finger on the problem.

Anyone else have K20 on Dynapack numbers raw numbers no TC- ratio added to show engine hp, but actual hub hp?

this engine should do 240-250whp.
 

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You are the first one measuring the low speed cams
. Sorry for my wrong assumption.

Normally the high speed lobs are the one you want to know the piston to valve and valve to valve clearance, as these should be the only one touching the piston or the exhaust valves, otherwise I would assume a NON-VTEC setup or a too huge low speed cam which likely need an increased idle speed of more than 1200 rpm.

Thanks

This explains much. For a non cam phasing setup you need to adjust for an compromise, not to much advanced, but also not retarded for max power only, just like that so you find the best powerband you need. Advancing support always the left to mid side of the engine speed band of that cam (here high speed powerband). In your case of having a pure high power camshaft you need to think about more retard and to increase your engine speed. Like drmo already stated, this is a 273°@1 mm lift cam, which is for 86 mm stroke a pretty looooong duration. For a 11.500 rpm 78.5 mm stroke engine you don't need to go over 265°@1 mm with the right induction and header design, just for your comparison.

I would also agree with you, I also wanted to wait for further information, especially the ignition data could tell us more about a VE or combustion related issue. But my feeling is also more into VE direction, just because of the duration, which need an awesome induction and piston speed to get this chab running.

Sorry for late response. But at it again. I had nothing todo with intake manifolds and exhaust system. 2 other companys custom built that. The pipes are 50.2mm outside and probably around 46-48mm inside (dont know the thickness) 750mm until it goes to 4-2 and than 1. 3" system the whole way and race cat and the end bumper (as regulation says you have to have it in rally).

The intake are 51mm tapered jenvey throttles
https://store.jenvey.co.uk/throttle-body-kits/honda/honda-k20-ep3-sf51-taper-kit-ckha07-kit

Ign between 27-33degree I dont have the ign table at hand now. But its tweaked for every cam adjustment to find more.

I'm going to test milder cams now Group-N rally cams. they are quite much milder, between 245-255degrees at 1mm have no exacly cam spec on them.

I hope I can atleast find some hp here to be abel to point the finger on the problem.

Anyone else have K20 on Dynapack numbers raw numbers no TC- ratio added to show engine hp, but actual hub hp?

this engine should do 240-250whp.
This is a dyno from a k20 on a dynapack txt is set to 1.00 so it's measuring power to the axles/ hubs.
 

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Engine K24,Z3 engine stock, inlet manifold Skunk 75mm manual throttle body, Nissan SRdet turbo 10lb boost, fuel E85
Haltech Elite 1500 ecu.7000 max rpm
285 RWHP
432ft lb torque
dyno sheet attached
Blue line is the Orig K20 Z4 Type R engine for comparison


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