Ways to combat detonation?
#1
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What are the best ways of combating detonation?
Mapping a friends engine at the mo, but have had to remove alot of ignition advance to get rid of the detonation.
Down to about 13 deg @ 0.5 bar under load.
I think most of this is due to the poor chamber design he now has after fitting a decomp plate (no more squish).
I know that backing off the advance moves the ignition event back in the cycle and lowers the post ignition cylinder pressures which in turn prevents post ignition gases from igniting on their own after the spark.
I was just wondering if there are any other methods of reducing det that i could use?*
The ACTs are already pretty low and the engine also runs at a decent temp.
Would water injection give me any det protection other than cooling the charge?
I realise stu might not want to give away his secrets, so one for the home mappers really.
Any suggestions welcome.
Cheers,
DC.
* bar removing the plate and rebuilding with some dished pistons and/or careful enlarging of combustion chamber. Not my engine so can't open it up.
Mapping a friends engine at the mo, but have had to remove alot of ignition advance to get rid of the detonation.
Down to about 13 deg @ 0.5 bar under load.
I think most of this is due to the poor chamber design he now has after fitting a decomp plate (no more squish).
I know that backing off the advance moves the ignition event back in the cycle and lowers the post ignition cylinder pressures which in turn prevents post ignition gases from igniting on their own after the spark.
I was just wondering if there are any other methods of reducing det that i could use?*
The ACTs are already pretty low and the engine also runs at a decent temp.
Would water injection give me any det protection other than cooling the charge?
I realise stu might not want to give away his secrets, so one for the home mappers really.
Any suggestions welcome.
Cheers,
DC.
* bar removing the plate and rebuilding with some dished pistons and/or careful enlarging of combustion chamber. Not my engine so can't open it up.
#3
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your options are:
a bit more fuel...
lower the boost....
drop the act....
back off the ignition.
Its best to run as much ign as you can even if it means dropping the boost.
Alex
a bit more fuel...
lower the boost....
drop the act....
back off the ignition.
Its best to run as much ign as you can even if it means dropping the boost.
Alex
#4
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Originally Posted by chip-3door
What AFR are you running?
Fuel is a pretty good Det surpressant!
Fuel is a pretty good Det surpressant!
#5
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Originally Posted by Garage19
Originally Posted by chip-3door
What AFR are you running?
Fuel is a pretty good Det surpressant!
Fuel is a pretty good Det surpressant!
Looks like the options are pretty minimal!
What CR is it?
Can you do anything about that?
#7
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Originally Posted by Mike Rainbird
I would not recommend using WI as a det suppressent, as if / when water runs out / jet gets blocked - engine goes BANG.
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#9
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CR is a knats cock under 8.7:1.
Would like to be running 10psi in the end. I have dialed out all the det so far at 7 psi but it just seemed like quite a low advance figure for that boost/cr setup.
Do you think the lack of squish makes that much difference?
Not sure that shed loads of fuel is the best way to combat det / run an engine. Our local so called tuner once showed me a RR printout of his cossie running 9:1 afr and seemed to think it was fueling great!
Would like to be running 10psi in the end. I have dialed out all the det so far at 7 psi but it just seemed like quite a low advance figure for that boost/cr setup.
Do you think the lack of squish makes that much difference?
Not sure that shed loads of fuel is the best way to combat det / run an engine. Our local so called tuner once showed me a RR printout of his cossie running 9:1 afr and seemed to think it was fueling great!
#10
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8.7:1 isnt exactly high compression, so thats lil strange.
GTST skylines are 9.5:1 as standard and ive seen them running 1.5bar no problems on pump fuel
Gotta be down to huge squish area surely? Prob would work better without the decomp plate!
GTST skylines are 9.5:1 as standard and ive seen them running 1.5bar no problems on pump fuel
Gotta be down to huge squish area surely? Prob would work better without the decomp plate!
#11
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Originally Posted by Mike Rainbird
I would not recommend using WI as a det suppressent, as if / when water runs out / jet gets blocked - engine goes BANG.
I have monitored the ACTs on this engine and as far as i can remember they were pretty good.
#12
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Originally Posted by Itsmeagain
8.7:1 isnt exactly high compression, so thats lil strange.
GTST skylines are 9.5:1 as standard and ive seen them running 1.5bar no problems on pump fuel
Gotta be down to huge squish area surely? Prob would work better without the decomp plate!
GTST skylines are 9.5:1 as standard and ive seen them running 1.5bar no problems on pump fuel
Gotta be down to huge squish area surely? Prob would work better without the decomp plate!
Think it must be the lack of squish that encourages the det?
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![Default](https://passionford.com/forum/images/icons/icon1.gif)
Originally Posted by Itsmeagain
Originally Posted by Mike Rainbird
I would not recommend using WI as a det suppressent, as if / when water runs out / jet gets blocked - engine goes BANG.
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I.e. WI shouldn't be kicking in whilst driving around normally.....
Another option is higher octane fuel, but again this is a compromise, unless you have easy access to run it all the time (or dual maps)
If you can't reduce det' to an acceptable level, then something is amiss (as you've already said) - do you really want to map a 'compromised' engine??
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There's a knowledgable chap who knows his BMW's on here and a couple of users with Megasquirt experience also. Maybe edit the post title and add BMW 318 & Megasquirt.
#21
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Cheers Billabong.
This is my fourth MS install/mapping. So pretty familiar with the MS kit.
But being my fourth engine to map, still on a steep learning curve where mapping is concerned!
This is my fourth MS install/mapping. So pretty familiar with the MS kit.
But being my fourth engine to map, still on a steep learning curve where mapping is concerned!
#22
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Originally Posted by Billabong
There's a knowledgable chap who knows his BMW's on here and a couple of users with Megasquirt experience also. Maybe edit the post title and add BMW 318 & Megasquirt.
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Its not an ideal engine to turbocharge, your porbably finding the limits of the combustion design.
Alex
#26
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Originally Posted by Stu @ M Developments
You have changed the spark plug heat range havent you?
So what your saying is the plug electrodes are running too hot and in turn causing the detonation?
So simply trying a cooler running plug may help?
Will give this a try at the weekend. Dial some of the advance back in and let you know the results.
Thanks,
DC.
#28
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Originally Posted by chip-3door
Keep us posted, very interesting topic ![Top](https://passionford.com/forum/images/smilies/smile011.gif)
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Chap is putting a new clutch in it as we speak. Last mapping session, as we started pulling the fuelling map closer to ideal the worn clutch started deciding it couldn't cope with the new found torque!
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#32
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Smit,
A friend of mine. Not sure you know him.
If you are down the pub (sorry, truck stop
) next Wed i will try and bring it along. Will take you for a spin if yer fancy it?
Yep 8.7:1, but been doing some research i think Stu is right about the heat range of the old plugs. Way out!
A friend of mine. Not sure you know him.
If you are down the pub (sorry, truck stop
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Yep 8.7:1, but been doing some research i think Stu is right about the heat range of the old plugs. Way out!
#34
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Eye, but with an aluminium plate!
Chap bought it from Ferriday. I was a bit worried about it so had a chat with Mike something un pronouncable from ferriday and he seemed to think it should work as an extension of the head and hold the cylinder pressures ok.
Seems to be holding up ok so far...
Still loose any decent squish the piston/head design had though!
DC.
Chap bought it from Ferriday. I was a bit worried about it so had a chat with Mike something un pronouncable from ferriday and he seemed to think it should work as an extension of the head and hold the cylinder pressures ok.
Seems to be holding up ok so far...
Still loose any decent squish the piston/head design had though!
DC.
#36
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Squish is of course very important, but its not the end of the world at those power levels.
Lots of people on big (well ish relative to cossies!) power vauxhall engines use 1.9mm gaskets to lower the CR and seem to get away with it just fine.
Obvously taking some metal out without ruining the squish would be better, but i personally dont think its that causing the problem.
Lots of people on big (well ish relative to cossies!) power vauxhall engines use 1.9mm gaskets to lower the CR and seem to get away with it just fine.
Obvously taking some metal out without ruining the squish would be better, but i personally dont think its that causing the problem.
#39
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Originally Posted by J871yhk
Its not an ideal engine to turbocharge, your porbably finding the limits of the combustion design.
Alex
A decomression plate is a bodge!
Thats why your getting det, very bad combustion chamber design. You've change the attributes of the CChamber completely, things like squish, flame front and end gasses are now completely different to the original design.
Alex
#40
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Originally Posted by Garage19
Nope. Custom tubular exhaust manifold and modided stock inlet.
Surely a 323 would be a six pot? Or did Europe get a four pot version?
Surely a 323 would be a six pot? Or did Europe get a four pot version?
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