Tuning advice needed on BC Stage 2 K20a for circuit car

K-Series Programmable ECU Calibration updates / downloads
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DXBHSV
Posts: 3
Joined: Thu Mar 28, 2019 10:14 am

Tuning advice needed on BC Stage 2 K20a for circuit car

Post by DXBHSV » Thu Mar 28, 2019 1:01 pm

Hello Guys,'

Ive recently replaced factory RSX-Type S motor with a replacement built motor, which I believe originated from KMod. Ive used a base map from the forums that maxed out the cam angles at 30deg, but ive been told I could go higher on this 35+??, As im a bit of a noob at this and also cautious as I dont want to bin another motor ( first suffered oil surge)

New engine: Approx 3 hrs run time, used as a Plan-B-Team engine in case of a failure in endurance racing
12.5:1 Compression on Wisco Piston W/ Skunk2 rods
BC Stage 2 All Motor cams, ferrea valves, springs
550 RDX injectors with PRB Intake manifold w K-tuned 70mm , all unnecessary ports blocked off. except idle control valve
Basic 4 to 1 headers to a modes 2.5 in exhaust.. ( no rear muffler)

Im running the V4 ECU from my RSX typeS and the loom and all sensors from previous motor.
I have a PLX wideband that is providing a the A/F on the digital channel 0 , which so far has been very impressive. Im running a 0-5v Oil pressure sensor on Analogue ch 7 for oil pressure monitoring

Car has now has a clockwork racing baffled sump and i have a 3 Qrts Accumsump plumbed in, set to 35psi . Oil cooler and koyorad radiator, the cooling system is actually too efficient , but build for endurance

5.1 final drive, standard gearing with OS Giken 1.1way LSD

I am noticing on the pulls today that there is a flat spot on acceleration and around 2.5K-4K rpm area, then it wakes up and goes. Again Im not super experienced with this so dont know where to start on modifying the tune I already have.. that was for a k24/k20 on stage 2 cams .

You can see on the data log the following times 4:20 ,5:05, 5:55, 7:05 , 8:03, this flatness or a little spike

I guess it needs more or less fuel in places. Im looking for a safe tune so the car can do 3-10 hr enduros , And I guess a bit more cam angle.

We have a great test street out the back of the workshop, so Ive done a few pulls and it seems to offer the same flat spot on several occasions

Car is in Dubai - so not a lot of tuners here, and they charge large sums for limited experience. so Im interested in a bit of crowd / expert advice

You can see the build on instagram @DXBHSV

Cheers
James

Having issues posting the log file due to size , will try trimming or can email to people
dxbhsv k20a Stg2.kal
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DXBHSV
Posts: 3
Joined: Thu Mar 28, 2019 10:14 am

Re: Tuning advice needed on BC Stage 2 K20a for circuit car

Post by DXBHSV » Thu Mar 28, 2019 1:12 pm

Uploaded as a zip file
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street test 2.rar
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Diogo Oliveira
Posts: 30
Joined: Fri Aug 05, 2011 1:54 pm

Re: Tuning advice needed on BC Stage 2 K20a for circuit car

Post by Diogo Oliveira » Thu Mar 28, 2019 8:47 pm

The flatness mentioned is because T.Pedal goes to zero, meaning you are lifting your foot from throttle. The spykes are occuring when the ECU goes from closed loop to open loop.

A/F is everywhere and closed loop parameters must be better dialed. Since this car is for circuit racing, there are some things you need to do that are different from drag or landspeed racing since you are not giving 100% throttle all the time....and these adjustments can make the difference to be a few tenths faster or slower. Ideally, unless you are into endurance, you should keep the ECU runing in open loop almost all the time to have full control over A/F ratio.

My suggestion: take the car to the track and make some laps....5 or 6 laps, and datalog those laps. By looking at the datalog you will know where were you at the track, the turns, straights and so on. Try to find the minimum T.Pedal used while taking those laps and change that value under Closed Loop parameters if your car is runing in Closed Loop with lighter throttle so you can make the ECU run in open loop so you can proper dial the fuel.

That would be the first step: dialing fuel to the best A/F ratio at the track. From there, tune ignition and cam angles (and again, you will need to find the cam angle where the engine gives the best response with partial throttle so you can have the best torque and power for turn exits).

DXBHSV
Posts: 3
Joined: Thu Mar 28, 2019 10:14 am

Re: Tuning advice needed on BC Stage 2 K20a for circuit car

Post by DXBHSV » Thu Mar 28, 2019 11:26 pm

Thanks for the detailed reply.
SO to follow your steps :
1. Keep car in Closed Loop for now, but the end game should be to run in open loop to "lock" in the settings
2. Go and do 5 Laps and Log that,
3. Find the min throttle pos. ( this is the next part i dont under stand as Im not 100% where and what needs to be changed in parameters)

I can also see i might have not got my seconds 100% in the previous message. With the throttle pressed down, it seems to have this flatspot and hesitation while building power, then hit the vtec cam and goes.. Is it worth while adjusting the Vtec window , or it that just opening another can of worms ?

Diogo Oliveira
Posts: 30
Joined: Fri Aug 05, 2011 1:54 pm

Re: Tuning advice needed on BC Stage 2 K20a for circuit car

Post by Diogo Oliveira » Fri Apr 05, 2019 9:31 am

Sorry for no replying earlier, sometimes I forgot to check here.

You can reach me at me email - wakko.tm@gmail.com - since I check it more often.

You want the car to run in Open Loop all the time unless you are going for an endurance race and fuel economy is a key to finish the race in a good position. But for now, and for prperly tuning it, keep it in Open Loop.

By dataloging some laps, you will be able to see the spots where the engine is still runing in Closed Loop and why is it runing in Closed Loop, so you can change those parameters and keep it in Open Loop all the time. That will give you better response specially at corner exists when you go from partial throttle to full throttle.

Regarding the hesitation, adjust fuel and ignition tables when your cams advance before VTEC kicks in. If you have your cams to advance to 50 before VTEC kicks in, but just before that the cam is advanced 20 degrees, it will run the tables all the way up to the 50 degrees tables, so if you dont have this "path" tuned, you can feel some hesitation and power loss. Also, before VTEC you can have your A/F a little bit leaner than normal (I used to have my engine tuned for 13.2 before VTEC), but that is something that needs to be dino tested and tuned.

Reach me up at the email I sent, it will be faster to reply and give you some assistance.....I have around 12 years of experience with K engines (NA and turbo builds) on road racing and Im shure I can help you out with your car.

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