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BTW deibral, the JDM F20C engine with 250 hp beat this V12 engine in it's stock conditions (CAT), which was around 2000 or so...nothing special :D.

Markus
Yes it does, but will that scale that much...? I would doubt that.

The new 911 GT3 with its 4.0l NA engine that was revealed in Genewa also looks fantastic :)
 

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Arouse the DAMPFHAMMER!
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Yes it does, but will that scale that much...? I would doubt that.
Just by Peak Power/Liter :).

The new 911 GT3 with its 4.0l NA engine that was revealed in Genewa also looks fantastic :)
Yes it does, I am a fan of the flat six concept, a bit heavy, but fantastic alternation of load capacity, simply no vibrations (no free moments and forces)...and Porsche did a fantastic Job: 125 hp/Liter, 115 Nm/Liter for a Euro 6 engine, which is specifically a more prosperous engine compared to the V12 Ferrari engine. Despite those engines are very good, the Honda K-series engine is the best engine for our purposes :).

Deibral, what would be your most loving engine torque line?

Markus
 

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Arouse the DAMPFHAMMER!
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For K24 it is a combination of TODA A3 torque line till 6000rpm and DC4 beyond ;)
We need a 4th lobe cam valve train :D.

Of course such a bandwith of high VE would be nice. With my engine project I aim to show a 4000 rpm broad bandwidth of 16 bar of BMEP is possible. No NA engine did show this before as far as I know. We will see...
 

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Im selling my rsp modified intake manifold ;)

"Its slighly ported and made to fit 70mm b series TB, plenum was increased with 10mm aluminum gasket.
Ive made 240hp and 220nm on k20a2 stock engine.
(Mod list: rsp manifold, rdx injectors, custom ex manifold, 60mm exhaust, 70mm s2 TB.)

PM me if interested.
 

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...rsp modified intake manifold...
Just for my curiosity, is the lower plenum part OEM? Those here in Europe have a big resonance chamber for noise reduction.

PictureEUDM RSP IM:

Source: clubcivicquebec.com

Markus
Yep, it is OEM, I ve removed it do clearance and without it it sounds closer to ITB. ?
 

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Arouse the DAMPFHAMMER!
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Yep, it is OEM, I ve removed it do clearance and without it it sounds closer to ITB. ?
Thanks for your informations. To clearance for engine mounted electrical water pumps or so?

Those resonance chambers are tuned for a certain bandwidth area of the noise spectra. This and more midrange VE support was seemingly claimed in the design spec paper. I assume now it sounds louder :wink: but maybe not like the most aggressive NA sound of ITB's :D.

Markus
 

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This thread seems to be extolling the virtues of the RSP Inlet manifold, and yet it is that manifold that is fitted to the lower power K20Z4 engine - according to Wikipedia. How can that be ??
 

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Yes agreed. But what I find puzzling is that the K20A in my race car is 212BHP standard on the supposedly inferior PRC manifold. Compared with as you say the 200BHP only of the K20Z4 when it has the superior RSP manifold. If that is the case, then where is the K20Z4 losing so much power against the K20A ?

The reason I ask is that I need to replace my water bubbling K20A, with our local scrappie's K20Z4, but I don't want to buy it if it loses me a shed load of power. Better I/L manifold or not.
 

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Different engines and different results. I don't think it goes about inferiority, just different aproach. K20A has higher compression ratio, different exhaust manifold and other smaller differences. The RSP IM has longer and wider runners than the PRC IM and therefore makes better torque. It is also easier to modify and experiment because of two peace design. Plenum can be enlarged more easily and trumpets inside changed (shortened/extended/different profiles made).

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OK. Different approaches I can accept, but despite having that better manifold the K20Z4 makes less torque than the K20A on the apparently lower torque PRC manifold. How do you explain that?

So is it just the compression ratio's and the exhaust manifold that accounts for the K20A's power output, or are the cams and head different too ??
 

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OK. Different approaches I can accept, but despite having that better manifold the K20Z4 makes less torque than the K20A on the apparently lower torque PRC manifold. How do you explain that?

So is it just the compression ratio's and the exhaust manifold that accounts for the K20A's power output, or are the cams and head different too ??
I said cr, header and smaller things, like cams that are a little different and head supposed to be different. The end result varies because of all the differences combined, even the factory tune is different.

Lets try it this way. In my opinion the RSP manifold is better then the RBC. We have made practically the same power with RSP compared to RBC, but much better torque (+10ftlb).There are a few tests floating around and I havent seen a better result with a PRC then the RBC. So, in conclusion I think that the RSP is better overall.

You can also have a look at the Katman's shoutout test on superstreetonline. The PRC is the worst manifold on that test regarding peak power and torque, if you exclude the RAA manifold from the test.


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Agree 100% that the RSP Manifold is waaaay better than the PRC.

Maybe it's better that I explain why I'm asking the question. Sorry, maybe I should have done that at the outset....

I bought a race car with a a K20A CN spec engine running the PNC manifold with Pectel ECU, dry sump, and fancy exhaust manifold. It produces around 240 BHP. Took it for a test run and it's overheating and making bubbles in the water. Head gasket I thought. so I took the head off and changed the gasket - the head only had about 1.5 thou warp so, should be OK, I thought. Following the re-build I found that it is exactly the same - blowing bubbles. The chemical tester fluid turning from blue to yellow - again. I'm now suspecting cracked liner, porous head or something. So I'm looking for a replacement block/head.

When I found a K20Z4 in the local scrappie I thought that would be a good replacement, especially with that nice RSP manifold, but I,m trying to understand the difference in the engines so I can decide what to move from one to the other.
 

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We should also make sure we are talking about the same setups here.

K24 vs K20
Peak power or area under the curve
deibral did a comparison of a ported RSP vs ported RRC and the ported RRC is the best all up especially if you are revving past 8k rpm.

If you can get an RSP cheap go for it, if you already have an RRC port it.
 

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Yes I saw that comparison. Useful. It's what made me ask the question about the K20Z4 engine it's fitted to as standard. i.e. what is it that makes it so down on power compared with the K20A? IS it just the Comp Ratio, Exhaust manifold and mapping? Because to lose that much power while having the increased power of that RSP manifold, the other components must be pretty awful power wise compared with the K20. IS the head different too ? Are the Cams different as well ??

I really need to know. Because if I buy the K20Z4 engine I'd look to drop those components from the K20A onto the K20Z4.
 

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Memory is foggy but I forget what cams the Z4's come with but iirc they have DC5/EP3 K20R camshafts or possibly FD2 R cams. If they have the grooved rings on the cam ends thats usually a dead ringer for Type-R cam profiles. The Z4 also has the better flowing RSP head (FD2 head). I would jump on a Z4 just for that and the RSP manifold is an added bonus, that is, if you're getting the Z4 for a really good price.

(hp/tq specs pulled from wikipedia)
K20Z4 (11.0) - 201hp/142tq
K20A-R JDM EP3 (11.5) - 212/149
K20A-R JDM DC5 (11.5) - 217/152
K20A-R FD2 (11.7) - 221/159
K20A2 (11.0) - 200/142
K20Z1 (11.0) - 210/143
K20Z3 (11.0) - 197/139 (poor thing)

So the Z4 has approx. 11hp less hp than an JDM EP3 K20A-R engine but power wise is on par with our US K20A2. As most know, the Z4 is a bastard-like Type-R engine honda slapped together for the UK.

Now an interesting thing is that the Z1 and A2 has a 10hp/1tq difference based on these specs. The Z1 comes with R-like (if not Type-R) cams and updated ecu + factory programming over the A2. Nothing else really changed engine wise between those 2 engines (possibly exh manifold design and exhaust piping size?). So cams and tuning alone is an approximate 10hp increase over an A2.

The Z4 probably has very conservative stock ecu mapping, possibly non-R camshafts as well, and the small differences DRMO mentioned too, that all adds up.

Have you checked/changed out your thermostat yet to single that out as suspect? also radiator cap in good working condition? sometimes the caps go bad and you'll get that boiling symptom.

if you're set on getting the Z4, most definitely swap the K20A cams over but please share some photos of the Z4 cams with us!! I'd like to know..

also note that if you do switch to the Z4, the RSP water neck is in a different location than the K20A PRB head. Its located on the side of the head w/a 45 degree neck angle vs on the front side of the head w/90 degree neck angle.
 

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Thanks for that. Sure, I'll take your advice and swap the cams then if you believe the K20A cams to be superior. I'll mic them first though to check if the lift really IS better on the K20A's. I know duration might be different too but I'm running out of time to go racing in France with it.
I also note what you say about the head being better on the K20Z4! I'll quickly compare volumes of the two head types andf depth of the head to see if theres potential to take a bit off the Z4 and increase compression to match the K20A's 11:1. Assuming the piston deck heights and piston pockets are the same (Big assumption!).
I think on this site there is a desperate need for a "Engineering Dimensions" Page so people can better educate themselves on what is / is not possible. What say ye ??
For example....the depth of my K20A head is 4.094" measured, The Block is 8.338" measured today, It would be good to have all the other ref info too for OEM Parts, such as Crank journal sizes Con rod C-C, Piston Deck heights, Head chamber volumes, etc.

What say ye ??

Oh and just to finish, my PRB-1 water neck is on the rear inlet side of the head, and I'm only swopping the engine because of the fluctuating temperature issue I mentioned, and that when I tested the water to see if the bubbles were actually coming from the combustion chamber the blue chemical tester DID turn yellow. I do hope I'm not wasting my time ! If I find tyhe bubbles are still there it's the rope and chair solution !!
 

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RSP collector can be modified by changing some of its elements, for example, the air horn. I have experience in making air horn from carbon

but there is no experience in calculating their sizes :)

If someone is interested in something we can jointly come up with something;)
 
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