matt_gsxr
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| posted on 29/5/11 at 09:04 PM |
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Engine sstuttering at 8300rpm turbo
Alright, what should I be looking for on this one.
I've been tuning up the engine today. Started a bit nasty and now pretty sweet. Not perfect but getting there and very drivable. Engine is
gsxr1100 and turbo from a Volvo T5, with MegaSquirt 2 running Extra 3.1.1.
So I have started trying to tune up the outer edges of the map. If flies to about 8kRPM, and then it goes a bit stuttery. I have logged it. The
trigger wheel is fine (no sync errors). Here is a screen shot from the offending region from MLV. The non-smooth curves and the drop off of
increasing RPM is the offending region.
It may be a bit rich because I didn't want to detonate another engine.
Have I got a problem with the spark being blown-out? I have dyna coils and standard plug and gaps.
I haven't done a 8kRPM plug chop, which is what I should have done.
Any thoughts on this appreciated.
Thanks,
Matt
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BaileyPerformance
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| posted on 29/5/11 at 09:44 PM |
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Looks like the TPS dropped at around 8500, was that you closing the throttle?
You said you are running it rich, looks like 12.5 AFR at 8000ish, that is LEAN, you should be running 11/11.5 to be safe, bike engines are weak, you
can melt a piston very very easily.
The Hayabusa i did a wile ago used a stock Ford gen1 zetec coil and custom leads, it rev'd to 14K without misfire with 1mm plug gaps, so if you
suspect a miss due to blowout replace the coils for a coilpack, 3.1 dwell, 0.6 spark duration in megatune
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BenTyreman
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| posted on 29/5/11 at 09:50 PM |
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It's quite hard to see but it looks like the fluctuations on the PW match the fluctuations on the TPS. Are you using some sort of blended
MAP/Alpha-N fuelling?
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matt_gsxr
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| posted on 29/5/11 at 10:26 PM |
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I am running SD multiplied with a Alpha-N table, so the PW fluctuations will be due to a bit of TPS.
In the second of the two surges I was braver and nailed the throttle so no TPS fluctuations, but still the stuttering (I can feel the stuttering and
the power drops off). I think this texture in the PW is a symptom of the stuttering.
Regarding the fueling. Rich/lean. I suppose what I am saying is that there is 10% more fuel going in at the same MAP and TPS and past the normal
torque peak. So I think there isn't too little fuel and that the AFR is getting upset by the missfire.
What are the symptoms of blow-out? If I close down the spark gap would that help fix it?
Sorry to be a newbie on this stuff. My thinking was with only 8psi, forged pistons (that get oil sprayed onto their undersides) and reduced
compression I should be pretty safe at 12.5, but I am still learning.
[Edited on 29/5/11 by matt_gsxr]
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BenTyreman
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| posted on 29/5/11 at 10:37 PM |
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Most of the boosted maps I have seen have much less ignition timing and run much richer than you currently are. Try around 20 degrees of ignition
advance and closer to 11:1 and see if the situation is improved.
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mikemph
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| posted on 29/5/11 at 10:41 PM |
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I would personally aim for around 12:1 on WOT.....This is what I have been told when I did mapping on the rollers with the guy that own the dyno.
I would go for iridium plugs with the thin 0.6mm electrode..... they seem not to suffer so much with the spark blow out..... and with still fire even
with super rich/lean mixtures. It may be worth going for a cooler plug too
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matt_gsxr
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| posted on 29/5/11 at 10:57 PM |
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Ironically I fitted some Iridium plugs that I had stashed away, but it was too late to go for a road test. I closed up the gap slightly.
Once the stuttering starts that AFR doesn't mean much at the moment. But will richen up my target map too, better to be safe than sorry.
Thanks all,
Matt
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mikemph
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| posted on 29/5/11 at 11:03 PM |
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If you need a co-driver to fiddle with the tables or keep an eye on the computer to help spot while you drive I'm sure I could find a few hours
one evening.
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matt_gsxr
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| posted on 29/5/11 at 11:27 PM |
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Kind offer.
I am not sure I would so readily volunteer for a WOT test with an unknown.
I think I am going to sort out some of the other details (intercooler, bonnet insulation it got up to 95degC, which is a bit warm for fibreglass) and
get the thing reliable before I expose others to this thing.
Matt
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mikemph
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| posted on 30/5/11 at 01:23 AM |
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no worries I am fairly local so give me a shout if you need a hand..... i will try my best to help
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MikeRJ
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| posted on 30/5/11 at 04:06 AM |
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The TPS reading starts to get a bit noisy before the first big dip (presumably when you backed off). Have you made sure the TPS wires are routed well
away from the coils and injector wiring?
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matt_gsxr
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| posted on 30/5/11 at 07:20 AM |
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I think Mike what we are seeing is a combination of concern, a slightly bumpy road and "the fear". What would be known in IT as a problem
between keyboard and chair.
I guess the TPS fluctuations would set off some Acceleration Enrichment, but I don't think this is the source of the problem.
What about this one for example. The fluctuations in the fueling are clearly correlated with fluctuations in the RPM, and these come about as a
result of the stuttering.
Like this one say (again the TPS does have a slight flutter 100 or 99, but not as much).
 
Description
I have far too much fuel at this end of the table, because when I first felt this I was worried that it was detonation. The AFR of 14.7 is an
artefact of the problem and not what the engine is getting.
Before the question comes up. Fuel pump is Walbro 255l/hour (over kill), Fuel pressure regulator is AIR004 (or AIR001, can't remember)
(Malpassi bought from FSE) and set at 3.25atm (not manifold referenced). Injectors are s2000. I think that the fuel is getting in there, but that
it isn't burning, but happy to be corrected.
I don't know much about this turbo stuff (only what I have read and broken).
Matt
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froggy
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| posted on 30/5/11 at 08:04 AM |
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Pin the wategate wide open and see if it stutters with no boost .
[IMG]http://i144.photobucket.com/albums/r187/froggy_0[IMG]
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matt_gsxr
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| posted on 30/5/11 at 09:20 AM |
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Interesting idea. The wastegate spring is 5psi, my MAP doesn't pay attention to such fripperies. Previously I had fairly serious overboosting
, but have put a baffle in the exhaust which helps with this and appeases the neighbours.
I will try your idea, but suspect I will still get some boost.
Previously this engine and set-up (without the turbo) reved up fine.
What would this tell me if it reved up fine?
Matt
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mikemph
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| posted on 30/5/11 at 09:43 AM |
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Have you taken it for drive since changing the plugs?
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MikeRJ
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| posted on 30/5/11 at 10:35 AM |
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What are you using for the crank position sensor - the original ignition pickup?
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BaileyPerformance
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| posted on 30/5/11 at 10:36 AM |
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quote:
Originally posted by BenTyreman
Most of the boosted maps I have seen have much less ignition timing and run much richer than you currently are. Try around 20 degrees of ignition
advance and closer to 11:1 and see if the situation is improved.
Please please be careful with ignition timing with boosted engines, i have only ever worked with hayabusa 08 NA but that engine made full power at
31deg timing, i would expect a boosted version to require 10degrees (maybe upto 14 at max RPM)
Aim for 11AFR, forged pistons are stronger and normally will withstand high temps but will melt nearly as well as a stock piston!
Turbo Zetec 8deg total timing at 1bar
Cosworth (stock engine) 7-9deg at 1 bar
Cosworth race engine 5deg at 22psi
Nissan 300xz (stock engine) 16deg at 1bar
Nissan race engine (550+bhp) 7deg at 25psi
The stock bike engine will breath very well, so loads of timing is not required, when you modify a car engine to make it breath LESS timing is
required.
These figures are what i have seen on my dyno.
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matt_gsxr
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| posted on 30/5/11 at 10:38 AM |
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Got some info from a serial gsxr1100wp turbo builder (he builds for others as well as himself)
AFR below 11.5 hurts power.
AFR below 10 gives miss-fires.
Aim for 12 at 15psi.
I guess I either have it too rich, or the spark be being blown away, maybe both.
I'll drop the mixture a little, and try the Iridium plugs.
Too wet to try anything out today.
Matt
[Edited on 30/5/11 by matt_gsxr]
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matt_gsxr
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| posted on 30/5/11 at 10:41 AM |
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quote:
Originally posted by MikeRJ
What are you using for the crank position sensor - the original ignition pickup?
I did have it running with the original trigger wheel (4 teeth, 1 long) for which I needed to build an additional conditioning circuit. I have
reverted to a 12-1 wheel while I get things tuned up.
Stock pickup which has been fine in the past.
MS2 logs trigger faults (sync errors) and none are found.
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matt_gsxr
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| posted on 30/5/11 at 10:55 AM |
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quote:
Originally posted by BaileyPerformance
quote:
Originally posted by BenTyreman
Most of the boosted maps I have seen have much less ignition timing and run much richer than you currently are. Try around 20 degrees of ignition
advance and closer to 11:1 and see if the situation is improved.
Please please be careful with ignition timing with boosted engines, i have only ever worked with hayabusa 08 NA but that engine made full power at
31deg timing, i would expect a boosted version to require 10degrees (maybe upto 14 at max RPM)
Aim for 11AFR, forged pistons are stronger and normally will withstand high temps but will melt nearly as well as a stock piston!
Turbo Zetec 8deg total timing at 1bar
Cosworth (stock engine) 7-9deg at 1 bar
Cosworth race engine 5deg at 22psi
Nissan 300xz (stock engine) 16deg at 1bar
Nissan race engine (550+bhp) 7deg at 25psi
The stock bike engine will breath very well, so loads of timing is not required, when you modify a car engine to make it breath LESS timing is
required.
These figures are what i have seen on my dyno.
Thanks for those numbers. I will drop the timing a bit more.
Stock timing on a GSXR1100w is 35deg. Ignition advancers add about 4deg to this and boost power (this is all Normally Aspirated). This is an older
engine than the Busa so I guess its less efficient.
My ignition map drops off with increasing boost, but I will make it drop-off more dramatically.
My intention is to pay to get the timing sorted out at some point, so will report back if this ever happens.
I got my present ignition values from here (at 8psi it would be 28deg), although the base map was based on a Suzuki Bandit RomRaided:
http://www.aperaceparts.com/COPE.HTML
Thanks for your help and good advice,
I am trying to learn
Matt
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BaileyPerformance
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| posted on 30/5/11 at 10:59 AM |
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I do agree running it too rich will hurt power, that is true on most turbo engines, but the extra fuel gives you some insurance while you are getting
the timing right, going from 11 to 12 AFR will only gain you 5% power at a guess, but one day you mite get the engine abit hot (hot air temp) and
cause det. The sensible way to go is run 12 at low boost (5psi), more fuel at high boost.(15psi)
The optimum AFR to ignite the fuel is 11AFR, more or less fuel is harder to burn.
I had problems with the stock Hayabusa COPs, swapped to Ford coilpack and all was well, wouldnt be too much effort to swap from dyna to Ford? i know
the Ford coilpack is good to 14KRPM
I would run 9/10 plugs (nothing fancy) gapped at 0.8mm
would be very interested on how much power it makes, what are they stock?
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froggy
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| posted on 30/5/11 at 11:17 AM |
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if you get a clean rev with no boost its showing your spark strength up as its hard work with the charge time on a bike engine to keep the spark
strength at high revs . it may well make a couple of psi with the gate pinned but should prove a point and from what you said it does sound like you
need a better spark 
[IMG]http://i144.photobucket.com/albums/r187/froggy_0[IMG]
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matt_gsxr
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| posted on 30/5/11 at 11:27 AM |
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quote:
Originally posted by BaileyPerformance
I do agree running it too rich will hurt power, that is true on most turbo engines, but the extra fuel gives you some insurance while you are getting
the timing right, going from 11 to 12 AFR will only gain you 5% power at a guess, but one day you mite get the engine abit hot (hot air temp) and
cause det. The sensible way to go is run 12 at low boost (5psi), more fuel at high boost.(15psi)
The optimum AFR to ignite the fuel is 11AFR, more or less fuel is harder to burn.
I had problems with the stock Hayabusa COPs, swapped to Ford coilpack and all was well, wouldnt be too much effort to swap from dyna to Ford? i know
the Ford coilpack is good to 14KRPM
I would run 9/10 plugs (nothing fancy) gapped at 0.8mm
would be very interested on how much power it makes, what are they stock?
Thanks again for your expert advice. It sounds like a good idea to aim for AFR of 11 whilst I get everything nice.
People drag these a fair amount so there are some silly numbers. But it seems that 250bhp at about 1atm should be reasonable, and matches the
Td04-16T power output in the Volvo T5R.
Stock power is rated at 150bhp (on carbs), but these figures are seen as optimistic by most even when new and this is a 1994 engine.
As you probably know these were used in sidecars and I am told (by a sidecar guy who also raced these extensively) that Steve Webster (serial world
champ) got 210-220bhp out of one (normally aspirated, but bored out, big valves, LCR's, etc etc).
At the moment I have wasted spark. So not sure how that would convert. I haven't got the end of my brick yet, so will try some of the ideas
from here which are mostly software before getting on e-bay!
Plugs were stock (9's), but I will try Iridium ones (as I have a set kicking around), and will check the gaping.
Thanks again,
Matt
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BaileyPerformance
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| posted on 30/5/11 at 11:29 AM |
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quote:
Originally posted by froggy
if you get a clean rev with no boost its showing your spark strength up as its hard work with the charge time on a bike engine to keep the spark
strength at high revs . it may well make a couple of psi with the gate pinned but should prove a point and from what you said it does sound like you
need a better spark
Running the engine with little or no boost will not show up a weak spark, the stock bike ignitions are only just good enough for NA.
The problem starts when the cylinder pressures get too high (under boost) for the spark to jump the plug gap.
The only 2 solutions are - close plug gaps or get a more powerful ignition setup
i know the stock Ford coilpacks are good for 24PSI on a zetec, it made 355BHP at around 7K, used same coilpack on a honda type R engine on MS in
grasscar, made 210BHP at 9K
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matt_gsxr
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| posted on 30/5/11 at 11:29 AM |
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quote:
Originally posted by froggy
if you get a clean rev with no boost its showing your spark strength up as its hard work with the charge time on a bike engine to keep the spark
strength at high revs . it may well make a couple of psi with the gate pinned but should prove a point and from what you said it does sound like you
need a better spark
Oh I get it.
This engine has reved to 11500rpm before with no previous sparking problems. But its a good idea as I could easily have component failure.
Good idea.
Matt
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