hi guys i did a reflash today and did a run at 2nd gear. wasnt able to do 3rd as there isnt any road long enough for mi. my torque seems yucky at only 300nm at peak 4.5k afterwhich it will start to die off. im doing 1.5bar of boost with this run. is there way i could make a stronger torque and make it hold longer till redline? what are the parameters i should adjust? octane or ignition map? im using a stock turbo.

 

I really think you'll have to do (at least) a 3rd gear pull to get a decent idea of your real torque curve. 2nd is pretty short so you're not loading the motor very much which is throwing off your numbers.

Anyway, I would think ignition timing would have the greatest effect on torque. You're aiming for peak cylinder pressure at 15* ATDC, so the closer you are to that the more torque you will make. Also consider that the HP/TQ formula is just an equation and HP will always be greater than TQ after 5252 RPM due to the calculation.

 

With the added caveat that your using the units hp and ft.lbs. If you use different units (in this case NM and kW) then the equation has different constants.

d

 

like it was mentioned, do a 3rd gear pull... these cars commonly lose boost at high rpm, that's where I ramp up the timing to help offset that.

 

over here we uses metric to do calculation. so in this case what is the correct formula

 

its not easy to do a 3rd gear pull. on our local highway, we have a speed limit of 90km/hr and doing a 3rd gear would easily go beyond the 120km/hr and risk being caught by our traffic law enforcer and get a heavy fine for it. i have attach my ignition map. its very much advanced to me. could i go further? is it normal for a 2nd gear pull to have knock less than 2

 

anywhere to tune in maylasia? there has to be some good empty roads up there that is resonably accessible to singapore

knock is not gear dependant. aggresive timing changes between cells is.

for example

at 2500 pm starting in the 160 load column you have the cells
12, 6, 3
then at 3000 you have
12,12,7

if you trace a line that represents your load as you move through the power band, any large jumps in timing can cause knock.

I try to keep the large jumps in timing to a minimum. If you can't get rid of the large jump in timing, check you fueling at those load points.

 

I've found knock to be highly gear dependent.

These magical sea of 8 ignition maps are usually happy in 2nd gear, but roast them in 5th and 6th and the knock sums can easily be higher than the timing numbers.

It can be offset by richening in higher gears and lower inlet manifold temperatures due to the speed of the air through the intercooler.

 

quite a bit of heat is generated in a 1/4 mile run as you traverse the gears.. by the time you get to 4th knock can crop up sometimes if you're tuned to the ragged edge.

also a tune for 3rd gear pulls doesn't always constitute a great 1/4 mile tune. I used 3rd gear to get me close and 1/4 mile runs to perfect it if that's the kind of racing you're into.

 

1/4 mile loads the car up far harder than even hard street driving in 4th gear which if it isnt knocking in the 1/4 it most likely wont ever knock on the street. Probably the best way to get a maximised tune is to log a couple laps on the road course. It makes for some bloody long logs to have to review, but it encompasses lots of gear changes and constant acceleration and heat soak. Least it worked for me.

JB

 

The issue I think with 1/4 mile is air temps waiting in queues which if your ECU isn't temperature compensated can then make the engine knock, however, if you run up to a 1/4 mile start line having driven there at speed with good airflow and off boost it seems to be quite knock free compared to hard use on the road. The real issue for knock is the repeated braking/acceleration at moderate speeds on a twisty track because the airflow may not keep the heatsoak at bay and the average power (and therefore heat) is massive for a road car's cooling that is designed for intermittent throttle use.

In the UK we call a 1/4 mile a drag strip, and a twisty circuit a track! Is the latter what you guys call a road course or autocross? We have very few ovals and drag strips, but quite a few "tracks". This is my local one http://www.knockhill.com/circuitmap.html - in reality it is an undulating, blind cornered white knuckle ride where a 500 BHP Evo/Subaru would only reach 120mph on the longest straight, and a lot of it is between 50 and 90mph. Here the inlet manifold temps reduce at the end of the straights and go silly high in the twisty bits.

 

I think we here in the states designate actual racing circuits as "Road Courses" because so many people drag race and it's kind of been deemed the default "track." We use the term "track" to refer to the drag strip as well as circuits. I don't think many people refer to Auto-X as the "track" though.

 

autocrossers rarely use the term "track" since we only race in parking lots and the course layout changes for each event. other than that, I call a road course a "track" and the drag strip is a strip unless it's street racing. Then we apply the newer more accurate term of "street bowling" instead of "street racing".

 

So the relevance to the original post might be that we need to watch the knock depending on gear/use, so map it to your situation and/or map it conservatively to give you a safety margin.

To get 2nd gear to really rock you need a full and fat boost curve. My preferred method is an AVC-R, if I didn't have this I'd want to look further into the OEM ECU as there is logic in there for low gear boost control, just not properly mapped out at this point.

My old E46 M3 used to get the better of a Subabishi of considerably higher performance out of even wet roundabouts (do you have these, they are great for getting a car out of shape on, only been to NYC, didn't see any when I was there must get to see more of the US) because whilst it had little torque or power it was instant and full even in the lower gears. Even then the Subabishi had an AVC-R and a smallish turbo that it easily spooled, but 2nd gear revealed its small lag and the E46 took advantage. Real world performance for many is 2nd gear transients.

 

4th gear is probably best to see where your at