SR20DET tuning help needed

[GrImMy]

Hi everyone.

So I am here to ask for some tuning advice on my SR20DET. I am using Nistune and have been for a few months, I am quite familiar with it and feel confident in tuning my fuel and everything else except my timing. This is the one area I haven't really played with because I'm afraid blowing up my motor.

Below are my fuel and timing maps as it is currently. I have been using this map for a while now and everything seems ok, no audible knock and my AFR's are 11.8-12.0 at WOT.

Here are the specs of my setup:
- W10 SR20DET
- Stock T25 turbo (mine is ball bearing)
- Boost adjusted on waste gate actuator, varies between 12-14 PSI.
- Stock turbo manifold
- Stock 370cc DET injectors (purple caps)
- SR20DE MAF (It is reaching its limit, hits 4.9V)
- Nisune Type 3

Timing:
http://i629.photobucket.com/albums/uu17 ... Timing.jpg


Fuel:
http://i629.photobucket.com/albums/uu17 ... s/Fuel.jpg


I have read a few manuals about tuning basics etc, but I just can't find a definitive answer regarding tuning timing. I understand that being on a dyno will be the best way to do this, but I don't really have access to one for tuning purposes. Any advice you guys could give me would be appreciated!

Also, this is at about 4500ft. altitude. Don't know if that helps.

Thank you.

[GrImMy]

Forgot to add. Fuel is 95RON

[Matt]

This is really where the dyno is required to perfect timing. Usually two indicators of when timing starts getting too high are when there is no further power increase (peak torque) and then the engine begins to knock

Being on a dyno is required to determine the first part and decent knock sensing equipment is required to monitor the second part (and subsequently pulling timing back)

As for the maps, PL is away this week but he might be able to provide some guidance with generally how he runs the timing maps on SR20DET when he gets back

[GrImMy]

Hi Matt thanks for the reply!

I know that a dyno is the perfect solution for tuning timing, but here I doubt that I will be able to use a dyno for an hour or so and tune myself. The dyno's here belong to tuners who do their own tuning and are almost always fully booked. This is the reason why I do road tuning.

I came across some software called VirtualDyno now, and it looks like it could help me out slightly by using the Nistune CSV's to calculate HP and TQ. Will do a log soon and check what's going on there.

Do you perhaps know what the safe timing levels should be more or less on my setup at my boost or even lower boost? I get the feeling that I'm running way too much timing. And I don't know if the stock SR20 knock sensor is really up to the job. Mine is buggered so definitely can't use it reliably but will sort that out soon. Would the stock sensor be OK to use or should I look into aftermarket equipment? Don't really know where/what.

[raddy]

Hi there. Recently I made quite extensive testing of phormula ks-3 knock sensor on ca18det and sr20det engines. I found that with correct setting and calibration of device you can clearly find situation that predict knock onset. With lot of back testing of AFR and timing influence I found that you can use whole scale of knock level, not just clearly (audible) knock situation. I can call it how "nervous" is knock activity. As soon as you learned reaction of it to different engine situations, you can dial your timing as good as on dyno, but on the road. You can distinct between clearly non-knock situation, any transition in knock activity (without any audible results) to the clear engine knock (also often hard audible).
In summary: buy good electronic knock sensing device, learn how to use it than tune ignition at the road.

p.s. very good position for aftermarket knock sensor/microphone on the sr and ca is one of 8mm bolt threads on the head that are located just above exhaust manifold....

[GrImMy]

Bump.. Is PL back yet? Need some advice from him. I have figured that on 95RON with my current timing and map I'm not pinging yet. I've read somewhere PL said the Nissan knock sensing is basically useless, but I'm pretty sure my timing is fine at the moment. Still need some help though.

[PL]

I'm back!

Those timing figures look pretty reasonable to me. I've not done tuning at altitude but I'd assume you could run more timing with less complete cylinder filling? Making your timing figures even safer.

Sounds like you've got things pretty sweet already and are using NIStune to good affect. Nice work. To further optimise your tune you'll need to get some sort of knock detection system and learn how to use it. The Phormula system that raddy described sounds like a winner.

Other methods I've used successfully are my favourite of a condenser mic in the engine bay hooked up to a little amp and some good quality headphones or even a simple piece of hose run from the engine bay to some ear muffs. Don't laugh - it's crude but quite effective.

So the bottom line (without having a dyno to measure torque) is to increase timing until you hear detonation and then back it off a bit. People have been doing this for years. It worked then and it works now. Engines are still engines.

The key with any of the "aural" systems is to learn exactly what detonation sounds like in your engine. The only way you'll do that is to increase timing too far. Obviously you need to tread lightly here. Don't add bucketloads of timing and then hold it a full boost for 10 minutes! Sneak up on it and do your experimenting at low boost and when you do notice the characteristic ting-ting-ting, back off fast.

Having a friend to help is good. And if you have some open roads with no traffic then you're in business. Don't do it around the suburbs and never try to drive and use the laptop. It's incredibly dangerous. I used to do this and I've had a couple wake-up calls. Just don't do it. If you can't get an assistant then do your editing while stationary. So add some timing, put your headphones on and drive. Make sure "trace" is active so that you can see what cells were accessed. Best is to have a friend edit on the laptop. You can call out when you hear detonation and they can edit the maps. You just drive. If you have a smart friend then they can work the laptop AND listen for detonation while you drive.

Anyway, I think you get the picture. Your maps already look good - they have the classic SR20 timing hole in the midrange with timing increasing as you reach redline.

Once you're happy it pays to take the car out on a hot day and give it a hard time while monitoring knock, as this is worst case. It's very easy to perfect your tune on a nice cool day and only driving in bursts only to have the engine rattle badly when the weather gets hotter and/or you drive it hard continuously. This is particularly so for small turbos being run close to there limit. They will heat the inlet air more than big turbos do, and detonation can quickly become an issue.

Enjoy!

Pete L

[GrImMy]

Like a boss. Thanks for sharing your knowledge Pete!

I'm glad my timing maps look OK, I had a look at it yesterday after again consulting the timing sections of the tuning manuals hosted by Nistune. I'm not too clued up on the technicalities like cylinder filling, etc. I saw that I might need to pull timing a few RPM earlier and start increasing it a bit earlier as well as full boost comes in a bit earlier than my map currently shows, but only just.

I'm trying to use Nistune to its full potential, my next step would be to faff around with ALL the maps, the little stuff to ensure that I fully understand how its working. Personally I don't have faith in the OEM knock sensor, but also don't know if an expensive system is worth it on an old rattly engine like mine to be honest. I've heard of the two methods you describe with the earphones and hose pipe. So does this mean you physically secure a big mic (like singers use?) close to the engine or against the engine? Then that mic runs to the smallest amp you can find (small car-audio amp OK? 300W?) and then that amp needs to support a 3.5mm jack for your earphones? Sorry I know its a dumb question but it seems effective so I'd like to try it out and need to source the correct components. I like this method a lot and will be useful when driving.

After hooking up the mic and headphones, I'll do some short pulls just to hear some knock. I'm naturally good at detecting funny things and noises in the engine bay so shouldn't be too difficult. I'm thinking of adding timing in 2 degree steps until I hear a ticking sound, I haven't heard knock before and I definitely need to find the knock threshold on this engine so this might be the only way for me to learn how it sounds..

I usually get a friend to drive for me, with me on the laptop monitoring and tuning. Unfortunately he won't be doing the tuning, I might teach him quick because for the sake of my engine I'd like to be the driver.

My last question is, is there sort of a rule-of-thumb for timing? For example like pulling or adding 2 degrees for every PSI of boost gained or lost. Or degrees/RPM as its reaching redline as the volumetric efficiency drops off?

In SA its naturally super hot, 30*C on a light summers day, and I'm using a small T25 turbo at 13PSi, and my air filter for my turbo sits right next to the throttle body But I will definitely put together this detection system you spoke of and give it a shot.

Once again thanks for the advice!

[PL]

Mine's a big dollar arrangement, let me tell you!

Mic is a simple electret mic insert which I've mounted in a piece of ally tube (about 19mm dia by 180mm long). A plastic pipe would be better. Insulate the mic as much as you can with foam etc from the tube to avoid picking up unwanted rattles. I even wrap a rag around the tube when I place it in the engine bay.

http://www.ebay.com.au/itm/Panasonic-WM ... 1c2871b15b

Actually this one would be even better cos it comes with a handy lead:

http://www.ebay.com.au/itm/6-METRE-TIE- ... 414fd030a7

Then you need a big budget high spec audio amplifier:

http://www.ebay.com.au/itm/34-The-Champ ... 1029656892

Then you can add your own headphones. This bit is harder than it sounds cos ideally you want a set that clamps hard on your head with big cups, so all external sounds are stopped. I used an old set of ex-military headphones. They're massive and people get a real kick out of laughing at me when I'm wearing them. But they work great!!!

PL

[GrImMy]

Mine's a big dollar arrangement, let me tell you!

Mic is a simple electret mic insert which I've mounted in a piece of ally tube (about 19mm dia by 180mm long). A plastic pipe would be better. Insulate the mic as much as you can with foam etc from the tube to avoid picking up unwanted rattles. I even wrap a rag around the tube when I place it in the engine bay.

http://www.ebay.com.au/itm/Panasonic-WM ... 1c2871b15b

Actually this one would be even better cos it comes with a handy lead:

http://www.ebay.com.au/itm/6-METRE-TIE- ... 414fd030a7

Then you need a big budget high spec audio amplifier:

http://www.ebay.com.au/itm/34-The-Champ ... 1029656892

Then you can add your own headphones. This bit is harder than it sounds cos ideally you want a set that clamps hard on your head with big cups, so all external sounds are stopped. I used an old set of ex-military headphones. They're massive and people get a real kick out of laughing at me when I'm wearing them. But they work great!!!

PL

And I really expected it to cost a lot. Will try my hand at this setup and come back with my results, maybe I'll even be able to give someone a decent base map to fine tune for their setups. The support from both you and Matt are outstanding, thanks a lot guys!

[Adrian]

g

[PL]

Spot on about the knock sensor DTC. You simply CANNOT tune if you have a knock DTC. Either fix the knock sensor/wiring or fake it out with a resistor. Don't leave it or you're in for toruble.

PL

[Adrian]

Spot on about the knock sensor DTC. You simply CANNOT tune if you have a knock DTC. Either fix the knock sensor/wiring or fake it out with a resistor. Don't leave it or you're in for toruble.

PL

Do you mean me? Writed that i bridge sensor with a resistor, or connect a working sensor whit a wire to ground. So no dtc code.

[PL]

Yeah, just backing up what you said about ensuring there is no knock DTC before tuning.

PL

[Adrian]

Yeah, just backing up what you said about ensuring there is no knock DTC before tuning.

PL

Okay