[K20actr.J]

Re: K23 project

No i running with prayoonto stage 3 cams now

 

[LotusElise]

No i running with prayoonto stage 3 cams now

Ok , let me know when you have measured the piston pin weigth. I will do the simulation of both setups (only one cam, as I haven't the Toda A3 valve lift motion data) and come back with the peak power shift.

Have a nice evening.

Markus

 

[K20actr.J]

Re: K23 project

OK.so the wall thikness of 89mm custom pistons is 0.153''
I don't have high accuracy weight scale.
This scale which i have showed about 80 grams
one guy here http://www.k20a.org/forum/showthread.php?p=1330713&highlight=wrist+pin+wall+thickness#post1330713
wrotte 72gr
(cp code 3k-6b)

On that occasion fell into the hands a stock k20 wrist pin. has .153 wall thikness, 22mm ex.diameter and lenght 52.2mm
cp lenght is 50.8mm and both the same weight


I think that:

the pins which run now are lighter and that is good for High rev.
cp infored me that i am ok to run those.
The 300 hp is a estimated number.(75 per cylinder). They don’t have a specific number for the pins. Every customer claims to make different amount of HP. They have some guys who push it a bit and exceed the 300 and have no issues.
CP Shelf pistons 89mm 12.5cr have .120'' pin wall thikness like these whitch running now

 

[LotusElise]

Thanks HP for data and cam specification.

For cam data I need valve lift data in a 1° ca increment, so the Toda A3 can't be simulated for now . Toda state always and only the advertising duration at a lift of 0.014" or so...this is accurate like assuming the weather in China should be the same as here , because at 0.014" lift you have no relevant air flow and it is not clear how much crank degree it will start flow later. Toda should do like Prayoonto, they state the duration@0.05", where flow already have started...this gives customer a better comparison of different cams...lift profile is still a secret even for cam specialists, but a sort of classification is possible .

BTW cam designing is one of the most complex processes I ever tried...I still can't handle it, as there about 20+ parameters to control (science fields: mechanic, kinematic, vibrations, thermodynamic, material) . Software and computer are only tools for that process, the designing process needs experience, design-fab-test-repeat-...no money, no time, no resources for that...but would be most interesting stuff .

I did a various valve lift profiles within a small and simple cam software I did for my simultions, just to understand which technology of the cam is relevant (incl. jerk, acceleration and velocity observation). As you once said, those engine block setups, like yours, don't love long durations but quick and steep ramps...very interesting games happens there between cam profile, static CR and some other engine parameters ...at that point valve train character (hertzian pressure, vibration harmonics and so on) was the limiting factor. I was talking with Nikos about doing together a adapted cam profile for that kind of setup (especially for my in and ex manifolds), but quit that for some reason. Seems to be I have to go with Prayoonto stage 3 or Brian Crover stage 3 .

The BC Stg3 seems to be the more attractive one (lower lift, bit longer duration, but don't know the steepness of the ramps?), as once the valve is lifted above 10 mm the flow doesn't increase because of the pressure drop there over the valve, because the pressure wave of 2nd order just arrives at the runner inlet and creates a big pressure "hole" at the valve...so only the piston is sucking. But when the valves begin to close...4 mm, 3 mm...the pressure wave is coming back for "ramming", beside scavenging the most important process...long duration cams sucks to utilize that...2 mm, 1 mm pressure wave max did a touch down at the valve and valve is closed. At this point it get's clear which influence the intake manifold has . A long duration cam still have open doors and need more revvs for better inertia effect to hold back the inducted air of the combustion chamber. But as you also mentioned, a higher displacement engine reaches max power peak earlier while the inertia effect is just air density related and stays at those higher revvs...

 

[02sik24a2]

297whp = 341bhp

I like to do double the liter so lets say 4.4L

That's 682bhp.

It would be a slaughter in the V8 world....More like a monopoly.

 

[K20actr.J]

K23 project

297hp not wheels.Wheels 270-275.This dyno (TAT) read engine power.It is very stiff and giving low numbers.The most stiffer here than any other dyno..stock k20a2 make only 185hp.Other dyno 2157cc make easy 310hp.Dont expect to take more pick number power.Ok realistically We have new bigger cams on lift &duration,bigger intake valves 3 angle job and more 100 cc from 2mm larger pistons and same intake manifold ported rbc.100oct gas.I hope to take more powerful rev range 6500- 9000rpm.I believe that to make 300Whp needs better intake manifold,gas, and and maybe higher compression than 12.8:1

 

[LotusElise]

Re: K23 project

K20actr.J, concerning the rod bolt dimensioning the following.

...showed about 80 grams...

I recalculated the dimensioning of the rod bolts, having that 80 g piston pin + 320 g piston + 560 g rod we got the following at 9 krpm:

• 3/8" rod bolts, ARP 2000 spec., fatique fracture safty = 1.51, yield safty = 1.02 -> wouldn't go that pass, to tight, as to less yield capability as temperature isn't of concern in that calculation!
• 7/16" rod bolts, ARP 2000 spec., fatique fracture safty = 2.11, yield safty = 1.42 -> :up:

Concluding that, fore sure, even with the higher weight, the rod bolt will handle it !

To answer the question for the piston pin and connecting rod I need more time as I didn't found the cross section drawing of that rods. Could you measure it like described in the following?

...cross section of the three critical areas of the rod (below pin bore at the tappered section, pin bore at 3 and 9 o'clock and big bore at 11 or 1 o'clock)...

Concerning the torque and power gain I did a calculation with only one cam (lobe profile is between Prayoonto stage 3 and 4):

• about 7 hp more but at least 500 rpm earlier (peak power@8 krpm with my header design)
• about 10 to 14 Nm more up to 7.5 krpm, than declining differnce to 6 Nm at 8.5 krpm

Peak power stays constant for over 500 rpm, because of it's flat end (beyond 8 krpm dtorque/drpm = -0.028 Nm/rpm). So, not knowing about the capability of the rods and piston pin, powerwise redline could be placed at 9.0 krpm. But as safety is always first I would like to calculate the above mentioned to finalize the setting.

What do you think?

BTW, computer runs actually your setup with my 2.3 liter-header and intake manifold design...just for curosity

 

[K20actr.J]

K23 project

forgot to give and rod bolt weight.if that can help i have one to measure .about manifoldld calculate and skunk 2 pro.the weight of each rod 580gr.not 560

 

[LotusElise]

...BTW, computer runs actually your setup with my 2.3 liter-header and intake manifold design...just for curosity

LOL ...10-15 Nm more beyond 6.5. That 2257 ccm engine gains really from right designed manifolds

forgot to give and rod bolt weight.if that can help i have one to measure...the weight of each rod 580gr.not 560

Did correct it, 3/8" rod bolt is out, 7/16" get's warmer

...calculate and skunk 2 pro.

Did configure a RRC, as I thought your IM investigation did show the RRC as the winner. Maybe another time...as I have no good measurement data about it, only rough assumptions. I would love to have the cross sections of the rod...redline fixing is of more interest

 

[K20actr.J]

well, tested on the dyno my new set up 89x90.7 (2257cc)
The engine just made the same power with the previous set up.
BUT 200 rpm higher.(8900).
Worked from 27 to 35 vtc but the best results was about 30 and much lower higher.

The previus set up 87x90.7 was anywhere so much better although that falls short 100cc

In the low range lost 15-20 hp/ 1.5kg torque and middle lost 25-30 hp and 3kg torque. at higher revs the different is lower 15-10 hp but anywhere toda cams had better curves.

Next step is that test A3 at 89X90.7mm.
prayoonto 3 needs more compression better gas than 100 ron
to make better curve.

Just wait to see in practice that next week.
Logically A3 wiil be more powerfull everywhere (low-mid-high)

 

[LotusElise]

...made the same power with the previous set up...200 rpm higher...was about 30 and much lower higher.

If I remember right my simulation needed values down to 20° VTC at max power with that setup and the SVM 212 cams.

The previus set up 87x90.7 was anywhere so much better although that falls short 100cc...In the low range lost 15-20 hp/ 1.5kg torque and middle lost 25-30 hp and 3kg torque. at higher revs the different is lower 15-10 hp but anywhere toda cams had better curves.

So 100 ccm more displacement and even less torque/power at low end and midrange...in a range of 15-30 hp. I am really sorry for you...those results are pretty a retrograde step, but I believe there something more holding your engine back as just a cam. As that cam isn't that far away from a Toda A3 and 20 hp are much more torque at the low end as in the high end. Because of that, I guess, there are some other brakemans like:

• possible wrong centerline position or exhaust cam lobe (would be my first priority of checking)
• possible weak compression of the cylinders
• possible leakage or obstacle of or in the intake runner or even leaking liner-head-transition
• possible wrong reading of the crank angle due to position of the trigger wheel
• possible opstacle in the exhaust (e.g. damaged CAT or socks )
• possible wrong ignition timing relation to crank wheel
• possible to big valve lash
• and so on...

Just to inspire you to review other items than just cams. I really can't believe that much power loss of low end and midrange of an cam which is not miles far away from a TODA A3 just some 1/10 of an inch too keep that figurative speech .

Are there some indicators like much shifted MBT's or ignition timing map or knock issues, which are really different to the previous setup? Greater knock likelyness could be an indicator of e.g. a bigger exhaust back pressure.

I would give that actual setup a chance of a review, because if it is engine related (not cam related) you would have that work anyway to do. But now there is a chance to learn more about a alternative cam...once it is thrown out it is all TODA related...from bad power status quo up to everything is fine and powers like it should power.

What do you think about that?

Markus

 

[K20actr.J]

The engine has not any issue.All tested and are fine!!I think maby need to have more patient and not write any catastrophic senario.all parts work perfect.oil press and level,coolant temperature and level,timing,positions etc.Do you know somewhere engine only 2257cc all motor which has issue and capacity 315hp?? Lol.As i wrotte those cams brake dynamic compression..needs more compression betteq gas and more cc. Pr3 has more duratiom and lift than A3..so simple.

 

[LotusElise]

Is it really that simple?

...Pr3 has more duratiom and lift than A3..so simple.

Really? Just for your interest some examples with an engine of 100 ccm more than your previous displacement,

• 15 hp loss@3.0 krpm mean a loss of ΔVE = 0.22
• 30 hp loss@5.5 krpm mean a loss of ΔVE = 0.15

That's like pretty much for...

...the Prayoonto stage 3 has 245 °ca@1.27 mm (s. their hompage) and the TODA A3 has 257 °ca@1.00 mm, a typical stage 3 cam has an gradient of 4°, twice of it gives you 8 °ca from 1.00 to 1.27 mm lift, so we get an assumption TODA A3 has roughly 249 °ca@1.27 mm.

Sorry HP, I would say too much loss as the shorter duration intake cam is the Prayoonto...exhaust it's pretty the same. Of course the situation is more complex due to different slopes of the cam lobes, also the centerlines of exhaust could be by supplier different, but ΔVE of 0.15-0.22 at a NA engine is like comparing a K20A2 with an K24/K20-Frank built in terms of power...there is substantially something different.

If I am wrong, the developer (I know his highly developed simulation tools and I know his teacher, which was one of the best in terms of engine simulation) of the Signature Cam Series of Prayoonto did something wrong or the dyno is decalibrated

 

[K20actr.J]

Re: K23 project

i took on my hands those cams (pr3 and toda stages3).I know very well why one says for better results make 13.7+ compression and the other manufacturer says 12.1-12.5 is enough.I have measured two cams..prayoonto 3 has 13.46mm lift intake, adv duration 314 degree.duration at @50 244. Ex cam 13.15 lift,adv duration 310 degree.duration at @50 230.I Know very well why toda like vtec 4700rpm and i know very well why pr3 needs 6000rpm.This is my practically experience about those cams...

 

[LotusElise]

...why toda like vtec 4700rpm and i know very well why pr3 needs 6000rpm...

HP, I see your point. A late VTEC is a good indicator, that the cam has a long duration...but also the engine could have bigger back pressure.

Let us assume you are right, the dyno was in good condition as the engine too and both cams were installed correctly. I would conclude the same as you did. But how would that fit to the picture of the duration@1 mm?

• Prayoonto did wrong measurements?
• Prayoonto's slope of cam lobe is steep than no other cam and behave like a bigger duration cam?

Both could be.

Just as a thought, what would happen if the exhaust cam is advanced? At scavenging it will close earlier and incoming mixture will see a higher back pressure during scavenging phase because ex's earlier closing. More residual gas will be in the combustion chamber, less fresh gas = VE is decreased, combustion slower, knocking more likely.

Now, the more engine speed, the less that mechanism get's effective because, as the engine more and more preferes retarded VTC, scavenging phase is reduced anyway. So what we will see is a later VTEC point (higher engine speeds), what we will see is a lower VE at lower engine speeds...the higher the engine speeds, the better VE can recover. BTW an advanced exhaust cam reduces working cycle efficiency, once it opens exhaust valve to early and it destroys a bit of the suction effect of the header.

I know, most of the points indicates clearly what you see and what you conclude, but just one point in that game is conspicuous, its that massive VE loss at lower engine speeds. I don't get money from Prayoonto making propaganda for it. I also don't want to criticize the installation quality, this could happen to the best. That's both is not my plan. I just want to show a other possibility for the same indications which can clarify that huge VE loss downlow, which is coequal of e.g. a stage 4 or 5 cam.

Its most likely, once the TODA A3 shows much better VE results, the exhaust centerline hypothesis is verificated ...as those cams are more or less of the same duration, the differences I guess would be in the range of smaller than 10 hp. The bigger intake valves (35.5 mm) and the bigger bore of your actual setup are VE enhancers of a higher level, once the cam performes better, we would see gains much more over your previous setup, we are talking about wins of 25-40 hp (compared to Prayoonto results) in the low up to high mid range...and that couldn't be possible with similar cam types. If they will show the same, the hypothesis was wrong and the exhaust cam was installed correctly. I hope that is not the case, as I am also going to test the TODA A3 .

In the end the engine will tell us !

Good luck with the TODA A3, I am of cheerful spirits that those shows much better results.

 

[K20actr.J]

Re: K23 project

Its not yet ready. 2 videos test..

 

[K20actr.J]

 

[LotusElise]

Re: k22 275whp/ k23???

Any update for the Prayoonto or TODA cams and tuning result?

Nice sound

 

[K20actr.J]

As I have said in the past this dyno
reads very low numbers.
For example, a stock k20a2 shows 184-190ps

test with prayoonto 3 291PS

test with toda A3 283(Red Line prayoonto 3 yellow Line toda A3)

Low and High pr3 cams are better
Midrage toda produce amazing torque.








After several attempts on the dyno
the gap closed.
low same power,mid toda better and High 7-9rpm pr3 better 6-7 ps to close the gap pick to 3ps

Maby pr3 needs more static compression than 12.6-12.7.
Theoritically long duration cams needs high cr
Better here is 100 ron oct pump gas.Don't know the static compression limit of this gas.

 

[flesh199]

great infos guys thx for sharing all of your r&d