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Discussion Starter · #1 ·
Hey there, I have a K24A in a Subaru BRZ that I use for NASA Time Trials.

We use an average whp system (https://nasa-assets.s3.amazonaws.co...SA_ST-TT_Dyno_Certification_Form--3-14-22.pdf) and under that the car currently makes 202whp with an average of 196whp. It is a JDM K24A, K20A2 pump, 50* VTC, KPower header, 3" exhaust, KPower intake manifold, 3" long tube intake, and a 65mm BRZ DBW throttle body.



After shuffling things around a bit classing wise I now have the ability to make another 4whp and I also have the ability to turn the power down up top by closing the TB. I currently have a 74mm Bosch TB sitting here which matches the port size of the KPower intake manifold which I haven't put on yet, but I figure is worth maybe 2whp up top.

I have a rev limit set at 7800, but I shift around 7400-7500 unless I need to extend a gear for a specific corner. The car generally lives in the 5000-7500 area.

I am not looking for a set of cams that adds only adds power >7000, is there a set of cams that would give me more power across my rev range? I was looking at the DC DICs, DC 2.2, and Toda A3. I'm happy to hear any input, it is much appreciated.
 

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In looking at your graph there may be some power still available with some tuning. That dip at 3500 is what has me thinking there could be some power left on the table. Especially if all your looking for is 4 more hp.

assuming you have a JDM K24a 3 lobe on both cams these numbers seem low. I’m in the same boat as you doing NASA with my CRX. Im going for 215 wheel hp out of my stock JDM K24a. only changes to mine is 64mm tb, type S oil pump, K tuned header. Plan on 3 in intake pipe and 3 in exhaust all the way out. My tuner is telling me we are going to have to detune things to limit top end power to keep it at 215. He estimates we we probably be at 220 otherwise.
 

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Discussion Starter · #3 · (Edited)
Yeah, it is a JDM K24A. The numbers are pretty consistent with other 86 swapped cars on the classing dyno, they usually fall between 200 and 205whp on 91 since we're eating a fair amount more in drivetrain loss over a FWD car. I do agree the 3-3.6k area looks weird, but I honestly never see it - the car is trailered to the track and extremely rarely street driven.

Ideally, I am looking to shift the curve up from 5k-7.5k and then I will chop the top flat via DBW to pull the average down. The car is competitive as-is, I'm just looking to squeeze a bit more.

I am guessing you're on cable and getting that .2 advantage too?
 

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When I was building my engine, I sent an email to Drag Cartel asking them their recommendations for a time attack/time trials engine -- albeit a turboed one. They suggested the DC2.2.
Can't hurt to ask them. They should know better than anyone else.
 

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Discussion Starter · #6 ·
When I was building my engine, I sent an email to Drag Cartel asking them their recommendations for a time attack/time trials engine -- albeit a turboed one. They suggested the DC2.2.
Can't hurt to ask them. They should know better than anyone else.
I'd planned to email them too. It seems the Toda cams are beloved on the forums so I was looking to see if there were any non-DC recommendations.

With current Yen to USD the Todas are on pretty steep discount.
 

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I'd planned to email them too. It seems the Toda cams are beloved on the forums so I was looking to see if there were any non-DC recommendations.

With current Yen to USD the Todas are on pretty steep discount.
I could not go against DC for anything, i had Prayoonto racing stage 2’s in my old K20z3 and gained only about 10whp over stock, my friend with his Z1 saw about 25+whp with his 2.2’s. Ever since then i’ve only looked at DC for my cams, i’ve used the 3.2’s, in my stock block application and used the 4.5’s in my 12.5:1 engine with fantastic results
 

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i had Prayoonto racing stage 2’s in my old K20z3 and gained only about 10whp over stock, my friend with his Z1 saw about 25+whp with his 2.2’s.
A clearer picture of the engine setup before and after would help to understand where the power add comes from. Especially headers and exhaust systems can support changes differently. I am just curious if this is a fair comparison, as I've seen differently on the DC 2.2 too.

Beside that the Prayoonto's S2 are much smaller:
So from there you may see the DC 2.2 is quite not a stage 2 cam, it is a camshaft for a 2-Liter-race-engine or a built 99 mm stroker. It compares more to a BC stage 3 then to the BC stage 2.
 

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A clearer picture of the engine setup before and after would help to understand where the power add comes from. Especially headers and exhaust systems can support changes differently. I am just curious if this is a fair comparison, as I've seen differently on the DC 2.2 too.

Beside that the Prayoonto's S2 are much smaller:
So from there you may see the DC 2.2 is quite not a stage 2 cam, it is a camshaft for a 2-Liter-race-engine or a built 99 mm stroker. It compares more to a BC stage 3 then to the BC stage 2.
That was more my position, not to compare them but more that the layout of options from DC is more into my preferences, the cams perform well overall with little to no tradeoffs
 

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That was more my position, not to compare them but more that the layout of options from DC is more into my preferences, the cams perform well overall with little to no tradeoffs
Understood. What engine size did you use it for?
 

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Ok, I am looking forward to see the results.

Nice approach, which also was used by member @JMURACN.
I race in honda challenge, so we do peak power not average power... I actually had more luck (the second dyno session), for my power band, running no timing and leaving the DBW alone.

the motors are so efficient that they will still forcibly make power with the flap only open 70-80%. Also, the increment of adjustment for the DBW in the flash pro was not optimal for my flat curve. I could make my 200hp cap much earlier and flatten the power with just messing with timing.
 
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Discussion Starter · #14 ·
I race in honda challenge, so we do peak power not average power... I actually had more luck (the second dyno session), for my power band, running no timing and leaving the DBW alone.

the motors are so efficient that they will still forcibly make power with the flap only open 70-80%. Also, the increment of adjustment for the DBW in the flash pro was not optimal for my flat curve. I could make my 200hp cap much earlier and flatten the power with just messing with timing.
I'm on Haltech with a BRZ throttle body. Funny thing is 100% throttle position target on the DBW opens it to like 120*, so I had to adjust max throttle percent opening to 90% for best power. I think I'll have to end up messing with timing too since the peak power difference was only 6-7whp 120* vs 90*, if I remember right.

Downside for me is I don't know anything about tuning so adjusting TPS vs RPM is easy, whereas timing isn't something I've done before. My tuner has a Dynapack and (as you know) classing is on a Dynojet.
 

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I could make my 200hp cap much earlier and flatten the power with just messing with timing.
Thanks for your feedback. More control would be possible with an smaller TB diameter, the stock K20Z3 is already big enough. I see your point regarding the control. The linear coherence of mass flow vs. TB angle is quite short on them. The smaller the wider it get, but also the flow will in total reduced.
 

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I'm on Haltech with a BRZ throttle body. Funny thing is 100% throttle position target on the DBW opens it to like 120*, so I had to adjust max throttle percent opening to 90% for best power. I think I'll have to end up messing with timing too since the peak power difference was only 6-7whp 120* vs 90*, if I remember right.

Downside for me is I don't know anything about tuning so adjusting TPS vs RPM is easy, whereas timing isn't something I've done before. My tuner has a Dynapack and (as you know) classing is on a Dynojet.
on my stock k20z3 we were able to flatten almost 30hp by going from 100% TB opening to 80% at open at 6k rpm... but the curve was not that great. we got a better curve with just doing timing. my engine is running zero VTC (well +1 or so here and there). I run it up to 8400 FYI. we were able to mess with the vtec cross over point, early ramp up on the vtc to get the 199.Xhp i need, and then taper it to 0* again...keeping a pretty fat curve. I'm basically at 199.Xhp every time i shift the car.

Thanks for your feedback. More control would be possible with an smaller TB diameter, the stock K20Z3 is already big enough. I see your point regarding the control. The linear coherence of mass flow vs. TB angle is quite short on them. The smaller the wider it get, but also the flow will in total reduced.
we had to kill the power much earlier than we wanted because of the 1k rpm increments the flashpro works with. we started closing at 6k rpms to make sure the curve didnt break 200hp, but it wouldnt make power early or flat.. it would keep climbing and climbing. to be honest it would just make power and keep making it the more the higher it reved... with the TB at 80% open. we could keep reving and keep making power.

we ran the motor at 8800 and ran it with no big lobe... 155hp. So we went to the big lobe a little early and with no VTC timing... bam it landed on 199.xHP early (you know i sent you the graph). we cleaned it up and lowered the redline to 8400 because even with zero timing, the more we spin it the harder it is to keep it under control... over 8400 we were breaking out too much on HP. I'd love to keep it at 200hp from 6.5k to 8800 :ROFLMAO: but wouldnt we all!??!
 
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The 3.2 is in the 87x99 and the 4.5 was in an 87.5x99 12.5:1 comp, 2.2 was used in an 86x86
Thanks for your feedback. Was the 86x86 a stock longblock (beside valvetrain)?
 

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we ran the motor at 8800 and ran it with no big lobe... 155hp. So we went to the big lobe a little early and with no VTC timing... bam it landed on 199.xHP early (you know i sent you the graph). we cleaned it up and lowered the redline to 8400 because even with zero timing, the more we spin it the harder it is to keep it under control... over 8400 we were breaking out too much on HP. I'd love to keep it at 200hp from 6.5k to 8800 :ROFLMAO: but wouldnt we all!??!
Ok, when you speak of timing, you mean the cam phasing (VTC), don't you? What you guys need is a torque control, which works on every atmospheric pressure and intake temperature. What you do is control in open loop VE, but that works out only for exact that one condition you have tuned it. No corrections for atmospheric conditions and all other power effecting parameters. A better method would be to control VE in closed loop, which would be possible with a MoTec M1 developer kit or with doing a one-handed handstand with the EngineLab EL129. The MoTec offers also a torque control model, which would work out, but need some dyno time to get it done right.

The most simple approach would be a smaller DBW TB, the controllability would be much better (= more TB movement for the same air mass flow increment). On most aftermarket ECU's you can choose the axis increments yourself, you just need enough cells or the right mix of increments width's if you have less of them. With that approach you would be able to run 200 hp from whatever till fully open engine speed or your chosen redline. The issue is, a TB has no linear correlation between TB increment and gas mass flow increment, it is no mass flow controller, it's only a pressure controller. That said the RBB IM would be the good choice combined with a tiny DBW TB as bottleneck and some correction tables for atmospheric conditions. That would give you more control by MAP control for VE control.
 
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