Jump to content

megasquirt questions


BlownCorona

Recommended Posts

  • Replies 261
  • Created
  • Last Reply

Top Posters In This Topic

Top Posters In This Topic

in all honesty this car isnt going to see a dyno. and im not going to be running it on the ragged edge of detonation either. im comfortable tuning the car with the tools i have.

 

i do understand the role a knock sensor has in order to get a safe tune and ill certainly be adding one, but the current tune is pretty conservative and it shouldn't be getting anywhere near detonating.

 

for reference here's the current map. i haven't fiddled with it at all since the car has no wheels right now haha.

 

kag3ms2u.pl3.jpg
Link to comment
Share on other sites

I dont know your engine but for a 10:1 or less compression N/A engine with relatively standard cams I would be surprised if you couldn't run 5 - 10 degrees more timing under load. but you need to research your particular engine first before getting carried away.

Link to comment
Share on other sites

I dont know your engine but for a 10:1 or less compression N/A engine with relatively standard cams I would be surprised if you couldn't run 5 - 10 degrees more timing under load. but you need to research your particular engine first before getting carried away.

compression is around, possibly slightly higher than 10:1 and it has a mild cam regrind. 

 

i might be able to squeeze a bit more advance out of the top end, but for what probably equates to a few HP for a few moments, id rather not risk damage. 

Link to comment
Share on other sites

its pretty typical for a tuned N/A engine to run anywhere from 30-40 degrees of advance at WOT depending on the engine cams and compression

 

my supercharged motor is running 22-25 degrees at WOT with 8psi albiet has low compression - I would expect you would be able to at least run that much and likely more than 30 degrees.

 

Id look at what the factory all in advance was and start maybe 5 degrees less than that and creep up to it a degree at a time and see if it keeps getting better and better if you add more timing and it doesn't get better then go back a degree and leave it. of course using 98octane fuel and listening for det etc all the time. I think it's pretty unlikely for that to be an issue running factory all in timing though. if its still getting better and you are feeling game you could keep going but thats where you really need the dyno and a det set to do so in a controlled manner.

 

the big advantage is you can run much more timing in the low load for better fuel economy and throttle response with a mapped ignition vs. what a mechanical only or even a mechanical and vacuum advance system might have given - in these areas you can get more aggressive with the changes and the numbers although you still want to be listening for det and feeling how its running.

 

but you are well right to be cautious - if you are not sure err on the safe side, make small changes and look for the map to be a sensible shape i.e. advance smoothly increasing with rpm and decreasing somewhat with load (map/tps) big jumps from one cell to another is very likely to make it run strangely.

Link to comment
Share on other sites

You can buy an unfiltered knock sensor for friggen cheap:

 

http://www.aliexpress.com/item/GM-Knock-Sensor-Ignition-Knock-Detonation-Sensor-for-2013-Chevrolet-Malibu-12623095/1738801957.html

 

Or some similar ones which have a wire/plug end on. (Donut shaped GM knock sensors are all wideband as best I know)

 

Bolt it to your motor, then sheilded wire to a 3.5mm jackpoint and plug it into your laptop as an amplifier and then use headphones to listen to the signal.

 

$30 for some extra safety vs a potential engine replacement is a good investment - and it's interesting to listen to.

 

I cant hear much of the engine over exhaust and intake noise at WOT, cant hear knocking like you can with a quieter car.

Link to comment
Share on other sites

do you mean the TPS ADC side? because that's the range my TPS puts out through its full sweep. (my setup does not utilize its full range of movement and would take a lot of effort and extra pulleys or something to do so but it has suitable resolution as is for the 12x12 table)

 

that unit of measure isnt %, its the analog output from the sensor. i believe you can switch it around to TPS% somehow but it doesn't achieve anything (im sure you know that KPR but more so for others) 

Link to comment
Share on other sites

Nar, i didn't know what adc meant, or more likely forgot as was using tps% on my ms.    ocd would get the better of me, with that tps adc scale 

 

 

Can't say i've used ms for years....  as you were

 

 

 

As far as the advance numbers go.  should be able to get a bit more aggressive, as others said.    get it up near 40 degrees on cruise.    wot, 30 should be plenty.  heaps of people over advance there na engines for no real benefit. but does depend a lot on the engine design how much will work best.     you'll likely over advance it before ruining into detonation if running good gas and not that much compression.

your setup wont be that hard to get close on the road.  just start with timing low. (about where is is now will be fine)     do wot runs in 2nd or 3rd.  add 2-3 degrees or so each time.  should easy fell it gain power. keep doing it, till it feels same.    the further away  from best timing, the more power it will gain each time you add timing.   so once you start to get close to best timing will gain piss all power.     its like a hill, once you get near the top power starts to flatten off.   you wanna be on top of that hill or almost at the top climbing up, not falling down the other side into a fiery pit of detonation

 

if you're limited by knock, totally different box of frogs

  • Like 1
Link to comment
Share on other sites

Join the conversation

You can post now and register later. If you have an account, sign in now to post with your account.

Guest
Reply to this topic...

×   Pasted as rich text.   Paste as plain text instead

  Only 75 emoji are allowed.

×   Your link has been automatically embedded.   Display as a link instead

×   Your previous content has been restored.   Clear editor

×   You cannot paste images directly. Upload or insert images from URL.

×
×
  • Create New...