Supercharged motor is alive! - Page 2

TimT · 05-20-2009, 04:05 PM

Forgot to mention. You can make a basic spark map 5 deg at idle (we use 10)

then ramp up linearly to say 28 at 3000 rpm... or 26 then flat line the map till redline..mimic the factory baseline map.

JohnJL · 05-20-2009, 04:07 PM

Hi Tim,

The ECU is Adaptronic. The owner/designer did the initial tuning and will be here in 3 weeks for a second dyno session. While he knows the ECU back/forward, he doesnt have boosted aircooled 911 tuning experience. I'd like to get it close so the dyno sessions are just fine tuning.

A screenshot of an ignition map would be most helpful, I can interpret/adjust/input into my software from there. I got quite fluent on tuning this motor and ecu when it was NA however I am starting from scratch as far as boosted tuning. This car is my personal Everest!

John

beepbeep · 04:49 AM

I've found some ignition maps in this thread:

http://forums.pelicanparts.com/showthread.php?t=452932

Part load 3.2 Carrera:

While this is a OEM N/A 3.2 map, it will give you hints about how it looks like. Obviously, you would need to knock off few degrees for twin plugs/safety and scale or interpolate it for boosted condition but it's good pointer of how it can look like.

part-load 993 map (twin plugs!):

More maps:

http://911chips.com/ignition.htm

full throttle 964/993:

JohnJL · 05-21-2009, 02:54 PM

Thanks, that's fantastically helpful!

Also have to thank John Dougherty and Hans Pedersen who have been answering questions by phone and email over the past week.

I had an interesting discussion with the Supercharger retailer yesterday. Went something like this;

Me: "Any ideas why I'm getting 10lbs boost max? The supercharger specs show at that rpm it should be putting out enough air to get 15lbs?"

Hans: "Its not unusual to see 4 or 5 pounds less than calculated if you have good flowing heads and cams. Its not the boost level you should care about, its the additional volume of air you are able push into the cylinders. That's assuming you have no leaks or restrictions. You can easily increase your boost level by using smaller ports and valves or a more tame cam, but that's not what you're trying to achieve. When you are measuring boost you are measuring pressure in the manifold. If your heads and cams are doing a good job of getting hte air into the cylinder than you will see lower manifold pressures, all else being equal."

This seemed to make some sense...any comments?

Forgot to mention the other day, we also checked compression, 127-130 lbs at each cylinder. DR20 cams both timed and triple-checked to 2.4mm.

TunersGroup · 05-22-2009, 05:18 AM

Quote:

Originally Posted by JohnJL

Anyone else think cam timing could be the culprit or any other suggestions?

Hi John,

I've just sent you a private message via the forum about the issue you are seeing. Your power curve sounds very different to the one Ray's motor makes.

- Adam

1980 911 sc · 05-22-2009, 06:45 AM

I know there is alot going on here, but sounds like the SC manufacturer is trying to avoid the idea that the SC is not larger enough to me...is he trying to say your motor is out pumping your SC...

Here is a differnt point of view... IF you motor mechanically pumps X CFM, is X CFM at a density associated to 10PSI the same as X CMF assoicated to 15PSI? This is not really true due to flow limitations etc., but as a rule of thumb it is good enough..

I have little tuning experience, so listen to the experts, it is just my reaction to the claims above...

Eric86Red911 · 05-22-2009, 07:54 AM

When I turbo'd my 1995, I had two problems that prevented me from making power (you should check these):

1. Excessive fuel pressure was locking up the injectors.

2. New spark plugs had a slightly large gap causing misfires (spark got extinguished by the boost). Changing plug type fixed it.

And my AFRs were fine despite those problems!

full quack · 01:10 PM

I agree with 1980 911 SC,
I too think the supercharger is under rated for your application. On V8 street supercharger applications, the blower is almost always running at 1/2 or 2/3 crank speed, NOT twice crank speed! That's for top fuel stuff.
A supercharger is a positive displacement air pump, so for every rotation, it pushes a set amount of air, period. The supercharger does not care what is down stream from flow, it simply pushes air at a given constant rate, at a linear progression of flow, with linear progression of rpm.
Therefore, it seems to me that if your engine is hitting a wall @ 3000rpm on boost & HP & torque, you have simply run out of air supply. Your AF ratios should still stay normal-ish since it is flow that your sensor plate is sensing.

But what the hell, I could be horribly mis-informed & delusional, but the statement from Hans, saying it is not uncommon to lose boost because of port flow, just does not sit well with my pea brain.

Mark

beepbeep · 05-22-2009, 01:39 PM

If engine was a perfect air pump then supercharger would develop same amount of boost troughout the rev-range. But VE actually changes trough the rev range depending on cams. Thus engine will accept different amount of air as VE changes.

If boost only varies between 10-11 lbs then it sounds like supercharger does its job but needs to be geared a bit higher (if more boost is needed). Of course, if supercharger is reaching it's maximum permissible speed at maximum revs with current pulley then smaller pulley isn't going to solve the problem and bigger supercharger is needed.

JohnJL · 05-22-2009, 03:26 PM

Thanks guys. I'll try to get all this in...

Adam, thanks for the message, I've replied. I agree, I also have Ray's dyno charts here and he was different results. My supercharger is 1 size larger and of the same design and manufacturer as Ray's. His is an autorotor 3150, mine is a 417. His puts out 1.5l per revolution, mine (is supposed to) put out 1.7l per revolution. His is running an 80mm supercharger pulley, mine is 60mm. Both our crank pulleys are 120mm. We use the same belt.

The supercharger is geared so it hits its maximum continuous-rated speed at 6500 rpm. So at 6000 rpm (3000 engine rpm, where things seem to go awry) it still has a lot of headroom.

Eric, that's an interesting comment on plugs. Hans also said that same result occurred with an Audi tuner in the US. I have iridium plugs gapped .85mm. Tops are one range cooler than the bottoms.

mppickett · 05:11 PM

John,

Your 1.7 liter Autorotor is about perfectly sized for a 3.2 liter motor. Putting too large a supercharger on an engine yields poor volumetric efficiency. The wisdom shared by your dealer is actually based in fact. I've seen intake manifold boost levels drop as I changed to better heads and exhaust plumbing. I've also seen boost levels go UP when I added an intercooler that didn't flow as well as a previous one. I was using Eaton blowers so your Autorotor should put out a little more volume at lower temperatures (a good thing). My experiences were based on 1.8 liter engines and 1 liter superchargers).

HOWEVER, you should probably be seeing a little better than 10 psi over 6000 engine rpm and keeping blower RPM at 13,000 or slightly less (unless you're into some really efficient intercooling, valves and exhaust parts). I'd guess more like 12-15 psi.

Goran has shared some of the info I used to build my most recent spark advance table. Here's what I'm currently using:

JohnJL · 05-22-2009, 05:50 PM

Awesome, thanks!

Well isnt it interesting what you find when check your work...I didnt hover over the tuner while he was doing his work but now going back over his logs I see some interesting information.

Most interesting is that the Dyno was measuring a max of 11 psi boost. However loking back at the logs I was getting a heck of a lot more than that...up to 23psi!?

Looking at the logs I see boost ramping up rapidly, up to 165 kps (23 psi, 1.62 BAR) at 4200 rpm! AFRs are 11.5:1 and ignition was massively retarded at 4-8 degrees btdc. That would explain the dead Innovate 02 sensor...must have burned it up!

That looks like a "smoking gun" to me. The dyno's MAP was way off (Maybe it was calibrated for 1 bar, not 3 bar?) and ignition was also off.

1980 911 sc · 05-22-2009, 07:06 PM

I think VE = motors ability to pump a volume of air / theoretical volume pumped. If you modify the internals of said motor(pump) you are changing that value. For example, a lower flow rate due to restriction in intercooler ends up reducing your motors ability to pump a volume of air (VE) and bigger exhaust may increase your motors ability to pump a volume of air.

I have heard alot of people (not here) say things like a turbo or charged motor is more than 100% VE, and I have to disagree, ignoring losses in things like cam overlap etc. All we are doing is increasing the density of a given volume of air...

VE is a function of many less variable (mechanical) things like cams, port size etc. Once an engine is defined mechanically, VE changes mostly with RPM, however i think, the flatter the torque curve, the less the change is. For example, my Varioram motor attempts to adjust intake runner sizes to better maximize the VE of the Engine at specific RPMs.

In this application, I see 2 pumps in sequence. If the first pump (SC) is more efficient the pressure between them goes up, if the second is more efficient the pressure drops.

If I had to stab at his situation here I think either his motor is really waking up at mid RPM and up and really beating the pants off the SC. Most would say this is due to some mechanical items, cams, port size etc. I see an opportunity, if we were to increase the output of the SC (bigger) we could see bigger mass air flow at high RPM...

I certainly don't want anyone to think I am flaming, in fact I am amazed at the amount of help i see in this thread, I am hoping to learn...

JohnJL · 05-22-2009, 08:48 PM

Yes, I'm amazed at the level of expertise and generous help too!

Just loaded another map which seemed to help the idle, though it still needs work.

Just as a point of clarification, in a boosted/turbo's motor, what's the proper convention for pressures...

For example if at idle I am reading 51kpa, that's obviously vacuum.

If I read 140kpa at a given RPM, that's 20.3psi. But you quote that in conversation as 7 psi, right? Since the first 14psi (101kpa) is normal atmosphere at sea level. And 165kpa is 23.9psi but that's discussed as 10psi boost. Correct?

beepbeep · 11:40 AM

When will people ditch the imperial units and use SI? Dabbling in foots, fingers, stones, inches, thousands etc. only messes up things. Even Brits (who invented bloody thing) converted to SI after lot's of moaning. So did NASA and US military

(NASA actually lost a Mars probe after someone mixed up foots and meters).

MAP sensors sense absolute pressure. So 0kPa is absolute vacuum, 100kPa is athmospheric pressure, 200kPa is "1 bar boost". Thus any boost sensed by MAP will register as 100kPa + boost. 140kPa is 0.4 bar boost or something like 6 psi or so.

sjf911 · sjf911's Garage

Quote:

Originally Posted by beepbeep

To begin with, I believe you should ditch the imperial units and use SI. There is no sense to dabble in foots, fingers, stones, inches, thousands etc. as it only messes up things. Even Britts, NASA and military uses SI

MAP sensors sense absolute pressure. So 0kPa is absolute vacuum, 100kPa is athmospheric pressure, 200kPa is "1 bar boost". Thus any boost sensed by MAP will register as 100kPa + boost. 140kPa is 0.4 bar boost or something like 6 psi or so.

Speak for yourself, we are at 92kPa ambient so I am already making boost at 100!

mppickett · 05-23-2009, 05:10 PM

So 165 kpa = 23.9 psi. If you take away normal atmospheric pressure (1 kpa or 14.5 psi) then you're looking at around 9.5 psi of boost. 11.5:1 is a reasonable and safe (although not optimal) AFR. I prefer around 12.5:1 once everything else is stable. It is possible that the low ignition advance would cause a very hot O2 sensor at that AFR.

For some reason I'm still worried that you've either got a slipping blower belt or you need a smaller pulley. I think you're on the right track about the spark advance.

mpp

Quote:

Originally Posted by JohnJL

Awesome, thanks!

Well isnt it interesting what you find when check your work...I didnt hover over the tuner while he was doing his work but now going back over his logs I see some interesting information.

Most interesting is that the Dyno was measuring a max of 11 psi boost. However loking back at the logs I was getting a heck of a lot more than that...up to 23psi!?

Looking at the logs I see boost ramping up rapidly, up to 165 kps (23 psi, 1.62 BAR) at 4200 rpm! AFRs are 11.5:1 and ignition was massively retarded at 4-8 degrees btdc. That would explain the dead Innovate 02 sensor...must have burned it up!

That looks like a "smoking gun" to me. The dyno's MAP was way off (Maybe it was calibrated for 1 bar, not 3 bar?) and ignition was also off.

TunersGroup · 05-25-2009, 07:58 AM

Quote:

Originally Posted by beepbeep

When will people ditch the imperial units and use SI? Dabbling in foots, fingers, stones, inches, thousands etc. only messes up things ... (NASA actually lost a Mars probe after someone mixed up foots and meters).

True story ...

http://www.cnn.com/TECH/space/9909/30/mars.metric.02/

- Adam

TunersGroup · 08:16 AM

Quote:

Originally Posted by JohnJL

Thanks guys. I'll try to get all this in...

Adam, thanks for the message, I've replied. I agree, I also have Ray's dyno charts here and he was different results. My supercharger is 1 size larger and of the same design and manufacturer as Ray's. His is an autorotor 3150, mine is a 417. His puts out 1.5l per revolution, mine (is supposed to) put out 1.7l per revolution. His is running an 80mm supercharger pulley, mine is 60mm. Both our crank pulleys are 120mm. We use the same belt.

The supercharger is geared so it hits its maximum continuous-rated speed at 6500 rpm. So at 6000 rpm (3000 engine rpm, where things seem to go awry) it still has a lot of headroom.

Definitely doesn't sound like a supercharger sizing issue to me then.

Also people should bear in mind that these superchargers are a positive displacement twin screw supercharger, so the speeds they spin at relative to crank speed are very different to some other supercharger designs that are more like a mechanically driven turbo compressor wheel.

Quote:

Eric, that's an interesting comment on plugs. Hans also said that same result occurred with an Audi tuner in the US. I have iridium plugs gapped .85mm. Tops are one range cooler than the bottoms.

What kind of ignition system are you running ? Some manufacturers of aftermarket ignitions advocate an increase in plug gap with some aftermarket ignitions.

As an example, MSD's FAQ page at http://www.msdpowersports.com/faq.html reads ...

Quote:

Spark Plug Gap

With a MSD Ignition you can run a wider spark plug gap than you would be able to with a stock ignition. The MSD Ignition has a higher voltage output and can jump the spark plug gap easier. As an example, if you normally would run a .028 inch gap on your spark plug with a stock ignition, you could run a .032-.034 inch gap with a MSD Ignition. There are variables that will affect the gap size: the higher the compression - the smaller the gap; the hotter the output of the ignition - the larger the gap, etc.

- Adam

TunersGroup · 08:40 AM

Quote:

Originally Posted by mppickett

For some reason I'm still worried that you've either got a slipping blower belt or you need a smaller pulley.

I'm thinking how handy a rev counter sensor on the supercharger pulley would be right now

If it does turn out to be belt slip, you could always go to a toothed belt like they run on drag racing cars ...

Interesting belt article here ...

http://machinedesign.com/article/industrial-belt-powers-top-fuel-dragster-1103

- Adam