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Arouse the DAMPFHAMMER!
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FYI, I was not trying to shut down your input…maybe just to put it in perspective.
Understood. Despite that I would be interested in it :D, if you don't mind to share.

Would you agree that 290-300 hp with good midrange (190-200 TQ) is still a very good result even in 2022??
Anytime, 290 [email protected] rpm corresponds within a 87x99 engine to 16 bar BMEP at peak torque it is even more, which is be higher level any F1 NA engine ever reached. Those peak around a level of 14.5-15.8 bar.
 

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USDM > *
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Understood. Despite that I would be interested in it :D, if you don't mind to share.

Anytime, 290 [email protected] rpm corresponds within a 87x99 engine to 16 bar BMEP at peak torque it is even more, which is be higher level any F1 NA engine ever reached. Those peak around a level of 14.5-15.8 bar.
I have no doubt the American dynojet numbers are inflated as you have stated previously. But the high numbers seem to be consistent for the most part.

In other words, 195-205 TQ on an American dynojet is still a good result even by 2022 standards for a street car…even if the true TQ is lower.

Also, the power band seems optimal for the rev range. Peak power hits around 7500 RPM which is ideal for setting the rev limit just under 8000 RPM for longevity.
Do you really think a stock port head would improve the power band from 5000-7500 RPM? I remain skeptical.
 

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Arouse the DAMPFHAMMER!
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But the high numbers seem to be consistent for the most part.
That what counts on first order.

In other words, 195-205 TQ on an American dynojet is still a good result even by 2022 standards for a street car…even if the true TQ is lower.
Another bench for the car as an system would be the 1/4 mile, what here is the 100-200 km/h bench mark. Yeah, it is definitely a good torque level, no doubt on that.

Also, the power band seems optimal for the rev range. Peak power hits around 7500 RPM which is ideal for setting the rev limit just under 8000 RPM for longevity.
Do you run your car on tracks or only randomly short stints on track an most is DD?

Do you really think a stock port head would improve the power band from 5000-7500 RPM? I remain skeptical.
If we can clarify the first question above we might see it :D. Anyway to entertain you a bit with stock ports you can read this: Simple 300whp recipe. K24/20 with all shelf parts. Also Dc4 vs Ultra 2 graph - Honda-Tech - Honda Forum Discussion and this to balance thoughts of advertising Drag Cartel 4.5's vs Ultra 3's vs. Ultra 4's - Dyno Results - Honda-Tech - Honda Forum Discussion
 

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2002 DC5 Type S
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For starters, I didn’t feel the dyno result was so bad. 290 HP and 205 TQ is a great result for a motor reving to 8000 RPM. And the midrange torque looks very good to me!
Indeed, those are great numbers for going to 8000rpm. I think the mid-range dip could be worked out some. Still 200wtq switching to the high cam is impressive.

I would like to see the industry play around with megaphone designs and shapes. Some of them could have less of a taper as the megaphone begins, almost like a typical piece of pipe but with little taper for a certain distance. Then the megaphone could take it's typical shape.
 

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Do you run your car on tracks or only randomly short stints on track an most is DD?

If we can clarify the first question above we might see it :D. Anyway to entertain you a bit with stock ports you can read this: Simple 300whp recipe. K24/20 with all shelf parts. Also Dc4 vs Ultra 2 graph - Honda-Tech - Honda Forum Discussion and this to balance thoughts of advertising Drag Cartel 4.5's vs Ultra 3's vs. Ultra 4's - Dyno Results - Honda-Tech - Honda Forum Discussion
This car is a garage queen. It only gets driven on sunny days less than 500 miles per year. I basically just drive it on the back country roads out where I live.
 

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That what counts on first order.

Another bench for the car as an system would be the 1/4 mile, what here is the 100-200 km/h bench mark. Yeah, it is definitely a good torque level, no doubt on that.

Do you run your car on tracks or only randomly short stints on track an most is DD?

If we can clarify the first question above we might see it :D. Anyway to entertain you a bit with stock ports you can read this: Simple 300whp recipe. K24/20 with all shelf parts. Also Dc4 vs Ultra 2 graph - Honda-Tech - Honda Forum Discussion and this to balance thoughts of advertising Drag Cartel 4.5's vs Ultra 3's vs. Ultra 4's - Dyno Results - Honda-Tech - Honda Forum Discussion
So I looked at these links. The second link was hard to follow (Due to dyno errors and MPH read out). The first link confirms my conclusion over the years. The power band was right-shifted (for maximum HP) at the expense of midrange torque. There is always a compromise.

I am not surprised to see a motor revving to 9500 RPM make >300 hp (but suffer from a hollowed out midrange). If you want to impress me, show me a motor make >300 hp revving <8500 RPM (with a big fat midrange torque curve).

Font Parallel Screenshot Rectangle Pattern

The intake manifold supported the peak HP out to 9500 RPM. I believe a ported head would’ve benefitted the motor even more throughout the power band (but I admit that is an unproven hypothesis).
 

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Arouse the DAMPFHAMMER!
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I am not surprised to see a motor revving to 9500 RPM make >300 hp (but suffer from a hollowed out midrange). If you want to impress me, show me a motor make >300 hp revving <8500 RPM (with a big fat midrange torque curve)
The 87.5x99 engine (1st link) on S2 U2 made 300 [email protected] rpm, torque is beyond the 200 wftlb line from 4500-7500 rpm. Compared to your setup, where torque exceed the 200 wftlb from 6200-7500 rpm, it doesn't look bad. So if you limit it to 8000 rpm you still would see 290 whp. But my point was the ports are stock.
 

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@ LotusElise
1. cl9 comes k24a3.
2. You can look at sheet of serge header (1) and plm header (2) at same stage of mods and compare it if you aren't cool with my paint work lol.
3. You are right about this (y), I made a error when measuring acceleration, I have not accounted for worn out tires when I did acceleration test. Before intake box mod I was on new tire and after intake mod I was on 4mm tire. That will make change in gearing and accuracy in speedo. Last week I put new tires on and tested my claim with ram open and ram closed. There was no difference in acceleration up to 140 ish. From 160-200 there was gain of 0.3 sec with ram open. All gains on dyno are from larger intake opening + v.stack and shaving air box. Sorry for confusion. Ram air is no bueno than... I tested intake temp with ram open and closed and it was the same 6c intake temp at 0c ambient temp so there is no point in having it.

4. It's dyno of my car with listed mods vs fn2 ctr with cai and exhaust don't know it its flashed or not. I wasn't expecting that big of a difference in low and mid power... Didn't know k20 is that bad. Good thing I skipped on ctr and went for cl9 when I was changing from s40t4.

I have talked to my tuner and he told me to go with porting rbb mani, k24z3 intake cam with 50vtc and 63mm single exit exhaust as I'm more into making power in low and mid range as the car is for daily use and I rarely push it to the red line. I'll post dyno when that gets fixed.
 

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The 87.5x99 engine (1st link) on S2 U2 made 300 [email protected] rpm, torque is beyond the 200 wftlb line from 4500-7500 rpm. Compared to your setup, where torque exceed the 200 wftlb from 6200-7500 rpm, it doesn't look bad. So if you limit it to 8000 rpm you still would see 290 whp. But my point was the ports are stock.
You’re right and I noticed that right after submitting. It also had the S2U2 manifold, and as Zof showed, it makes less power than the RRC everywhere under 8000 RPM. This makes me believe that dyno is “ultra” generous or maybe it’s just a miracle motor.
 

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Arouse the DAMPFHAMMER!
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S2U2 manifold
There are variants of the S2 Ultra IM, the Street and the Race, while the last can be modified with different offset frames to generate different plenum volumes. So which one of these did you test? I only know a test of user @deibral, which tested the RRC ported vs. the S2 U Street. Result was the U Street was not worth to swap for an ported RRC, see here: Skunk2 Street Manifold | Page 3 | Honda / Acura K20a K24a Engine Forum

Could you please link the @zof484 comparison of RRC vs. S2 U XXX IM? Would be great.
 

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There are variants of the S2 Ultra IM, the Street and the Race, while the last can be modified with different offset frames to generate different plenum volumes. So which one of these did you test? I only know a test of user @deibral, which tested the RRC ported vs. the S2 U Street. Result was the U Street was not worth to swap for an ported RRC, see here: Skunk2 Street Manifold | Page 3 | Honda / Acura K20a K24a Engine Forum

Could you please link the @zof484 comparison of RRC vs. S2 U XXX IM? Would be great.
It’s been a long time since I went through Zof’s posts but I think it was this thread:

Yeah, Deibral’s results are consistent with everything else I’ve read…the RRC is the king ding-a-ling under 8000 RPM. This is why I find that dyno graph above hard to believe. An RRC should’ve made even more HP and TQ, which seems totally unrealistic and not consistent with the majority of prior data we have to compare.
 

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An RRC should’ve made even more HP and TQ, which seems totally unrealistic and not consistent with the majority of prior data we have to compare.
Please have patience with me here and you will see where I am going with this. I believe the aftermarket was desperate to come out with a IM to sell to the public. I believe the aftermarket has struggled to create intake manifolds that can retain the assistance of VE to make the power Honda's cylinder head were designed for in relation to each cam lobe. From low-end to mid-range, being able to utilize the punch that is created at the VTEC crossover, and still deliver decent top-end gains. In most designs of aftermarket IM's, they are being designed for engines with an intake cam lift greater than 12.7mm. The Pracworks IM has short fat runners and the S2U IM's have short fat runners, high rpm's as well.

When I look at Honda BTCC IM's the runners are longer than the RRC's and look considerably wider / more area inside, similar to the RRC - not the improved RBC, the RBC designed for the K20 86x86 engine. The plenum's are also larger than the RRC. The RRC IM is the best example of what a IM should look like in relation to the cam profiles and the cylinder head port.

The RBC was always designed for a different head than the PRB-1. Seeing that Honda did not see the need to change the PRC cam profiles, that says Honda felt confident about that cam profile to cylinder head port relations. Making the changes in the IM (RRC) was the best fit for the 86x86 within the OEM guidelines of rpm usage. As far as S2U being a great aftermarket solution b/c of plenum adjustment, yes. The runner length should be sold in different lengths and dia's.
 

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Please have patience with me here and you will see where I am going with this. I believe the aftermarket was desperate to come out with a IM to sell to the public. I believe the aftermarket has struggled to create intake manifolds that can retain the assistance of VE to make the power Honda's cylinder head were designed for in relation to each cam lobe. From low-end to mid-range, being able to utilize the punch that is created at the VTEC crossover, and still deliver decent top-end gains. In most designs of aftermarket IM's, they are being designed for engines with an intake cam lift greater than 12.7mm. The Pracworks IM has short fat runners and the S2U IM's have short fat runners, high rpm's as well.

When I look at Honda BTCC IM's the runners are longer than the RRC's and look considerably wider / more area inside, similar to the RRC - not the improved RBC, the RBC designed for the K20 86x86 engine. The plenum's are also larger than the RRC. The RRC IM is the best example of what a IM should look like in relation to the cam profiles and the cylinder head port.

The RBC was always designed for a different head than the PRB-1. Seeing that Honda did not see the need to change the PRC cam profiles, that says Honda felt confident about that cam profile to cylinder head port relations. Making the changes in the IM (RRC) was the best fit for the 86x86 within the OEM guidelines of rpm usage. As far as S2U being a great aftermarket solution b/c of plenum adjustment, yes. The runner length should be sold in different lengths and dia's.
I wish someone would reproduce the Paul Brown BTCC intake manifolds for enthusiasts.
 

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USDM > *
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Please have patience with me here and you will see where I am going with this. I believe the aftermarket was desperate to come out with a IM to sell to the public. I believe the aftermarket has struggled to create intake manifolds that can retain the assistance of VE to make the power Honda's cylinder head were designed for in relation to each cam lobe. From low-end to mid-range, being able to utilize the punch that is created at the VTEC crossover, and still deliver decent top-end gains. In most designs of aftermarket IM's, they are being designed for engines with an intake cam lift greater than 12.7mm. The Pracworks IM has short fat runners and the S2U IM's have short fat runners, high rpm's as well.

When I look at Honda BTCC IM's the runners are longer than the RRC's and look considerably wider / more area inside, similar to the RRC - not the improved RBC, the RBC designed for the K20 86x86 engine. The plenum's are also larger than the RRC. The RRC IM is the best example of what a IM should look like in relation to the cam profiles and the cylinder head port.

The RBC was always designed for a different head than the PRB-1. Seeing that Honda did not see the need to change the PRC cam profiles, that says Honda felt confident about that cam profile to cylinder head port relations. Making the changes in the IM (RRC) was the best fit for the 86x86 within the OEM guidelines of rpm usage. As far as S2U being a great aftermarket solution b/c of plenum adjustment, yes. The runner length should be sold in different lengths and dia's.
I think my comment may have been unclear. I agree with you. The RRC is an amazing IM and in virtually every test I’ve seen it beats the aftermarket manifolds under 8000 RPM.

The point I was trying to make, is that I don’t really believe that 300 HP dyno graph because…
1) it uses a S2 ultra manifold which would make less HP than the RRC under 8000 RPM
2) that means an RRC on that motor should make significantly more HP on that motor…310ish HP?

That just seems too far fetched unless this is Churches dyno;)
 

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Still with my former K22 stroker preferred the power delivery of the RBC over the cnc ported RRC with its big peak at 6000 rpm and steady falling torque from there.
The RBC had as less steep torque increase towards the power band and it also declined less fast omitting the big torque peak. It felt more linear. AFAIK the RRC feature rather short equal length runners while the RBC feature unequal runner lengths provoking more of a flatter torque level.
 

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Still with my former K22 stroker preferred the power delivery of the RBC over the cnc ported RRC with its big peak at 6000 rpm and steady falling torque from there.
The RBC had as less steep torque increase towards the power band and it also declined less fast omitting the big torque peak. It felt more linear. AFAIK the RRC feature rather short equal length runners while the RBC feature unequal runner lengths provoking more of a flatter torque level.
Interesting. I wasn’t aware of these sublteties
 

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The RRC does better on built motors than a S2 ultra ? Even with the plenum spacers ? If so that is pretty damn impressive and I want to buy one lol. Even at 7-800$ new that’s far less than the latter with a 80-90mm tb fuel rail etc ..
 

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The RRC does better on built motors than a S2 ultra ? Even with the plenum spacers ? If so that is pretty damn impressive and I want to buy one lol. Even at 7-800$ new that’s far less than the latter with a 80-90mm tb fuel rail etc ..
That’s not what is being said here. The bulk of data shows the RRC beats virtually all aftermarket manifolds under 8000ish RPM. Beyond that, the S2U and other aftermarket manifolds will dominate.

So a drag car with built motor and a 9500 rev limit would benefit more from an aftermarket manifold. A great example of this was user 1EGlowbudget (?spelling) he had a built motor w/ 4Piston head and switched from an OEM manifold to the Xcessive center feed and made a ton of power up top.

Edit: Here is the thread
 

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That’s not what is being said here. The bulk of data shows the RRC beats virtually all aftermarket manifolds under 8000ish RPM. Beyond that, the S2U and other aftermarket manifolds will dominate.

So a drag car with built motor and a 9500 rev limit would benefit more from an aftermarket manifold. A great example of this was user 1EGlowbudget (?spelling) he had a built motor w/ 4Piston head and switched from an OEM manifold to the Xcessive center feed and made a ton of power up top.

Edit: Here is the thread
I am on the same page now thanks 👍 I have always liked the xcessive. I think they recently discontinued the K manifolds 😭
 
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