Todd's latest dyno with procharger supercharger and air / air intercooler @ 30psi
11-14-2008, 02:03 AM
#32
Drifting
Thanks for the info John,
When you say your turbo car, is that your Audi? What ignition system is being used with these coils?
Todd has already created a bracket system to use the Cayenne coils with the S4 head. The coils you are using look like a nice setup, stay with the OEM plug ends, just make the cable whatever length you need based on coil placement.
As for plugs, he's running NGK non-projected electrode copper. I do not know the number off hand, the heat range is equivalent to a Bosh 5-6 range plug.
What plugs are you using, and what is your plug gap?
When you say your turbo car, is that your Audi? What ignition system is being used with these coils?
Todd has already created a bracket system to use the Cayenne coils with the S4 head. The coils you are using look like a nice setup, stay with the OEM plug ends, just make the cable whatever length you need based on coil placement.
As for plugs, he's running NGK non-projected electrode copper. I do not know the number off hand, the heat range is equivalent to a Bosh 5-6 range plug.
What plugs are you using, and what is your plug gap?
I'd stick with the NGK plug. I think they make the best plugs out there. I run them in my built LS1. Todd's problem just seems to be lack of dwell time.
John
11-14-2008, 02:39 AM
#33
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Devils Advocate response.
(as you know) Its the boost Erik, that is blowing out that spark, or (technically speaking) creating an atmosphere in the chamber, mixed with the proper fuel ratio, that the collapsing field inside the coil that gets to the spark plug cannot now jump (without more tinkering past stock parameters)
(as you know) Its the boost Erik, that is blowing out that spark, or (technically speaking) creating an atmosphere in the chamber, mixed with the proper fuel ratio, that the collapsing field inside the coil that gets to the spark plug cannot now jump (without more tinkering past stock parameters)
my devil's advocate response----
there are plenty of domestics with blowers that don't have a problem with spark, and produce a lot more hp.
I can remember a friend building a stroked BBC back in the mid '70s with a 8-71 blower and carbs, and only used a dual point distributor with a Mallory coil. Never had a plug foul, never had ignition problems, never had a problem except for a dropped valve after street/strip running it for over three years.
the car weighed 4500 lbs and ran low 9's (1/4 mile) all day long. Drive it to the strip--drive it home.
Todd (and many others) is doing research that should have been done twenty plus years ago.......
My suggestion:
Electomotive COP (Carl is already working on this.....)
OR:
put a mag on it.
--Russ
11-14-2008, 07:37 AM
#35
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You are correct, this was all sorted out well over 20 years ago...in Drag Racing..
There are some rather neat tricks to running Methanol...
What they really need is a Drag racing mechanic to tell them
But as my opinion is worth nothing here, I wont bother....
You were almost there though with part of your post....about 50% of the way.
Plug gap reduction wont work though...
All the best Brett
11-14-2008, 09:33 AM
#36
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Last night Mike Schmidt (Z) informed me of something neither of us was aware of. Porsche switched to a different coil in 1989 for the GT. My first thought mirrored Mike’s; maybe Bosch simply stopped making the old one, which is not the case. Both are still available.
I have no idea what it would take to find out exactly what the differences are between these coils. I think it’s a safe bet the new is rated for a higher output then the earlier unit.
Both the S4 and GT use the same ignition driver, so it's not like they upgraded the whole system.
Brendan, few details you might not be aware of:
1. Todd's ignition problem first reared its ugly head a while ago when his peak boost was much lower. Increasing the dwell time solved the problem.
2. With this dyno session, the ignition miss is already starting at 21psi of manifold pressure.
I was using HP in my example above; I should have been quoting torque.
Intake manifold pressure is not the key factor here, cylinder pressure is.
Manifold pressure does not equal cylinder pressure. This is often confused.
Todd's peak torque is 614lb-ft @ 5500rpm. At this point he is seeing maximum cylinder pressure. This is not at peak boost or RPM. Torque is the best way to gauge cylinder pressure.
A valid comparison would be a similar car producing exactly half that amount of torque (or more), at the same RPM with a single coil.
There are 951’s producing over 300lb-ft of torque on the stock ignition system. Is this ideal? No, many people in the 951 world will be the first to suggest an upgrade of the ignition system for this type of power.
My 81 was making about 325lb-ft of torque @5500rpm when the blower was putting out only 10psi. Now that I’m up to 17 pounds of boost, I’ve surpassed this mark still using a single coil.
I too was having ignition issues until I simply replaced everything with new or known good parts from my 79.
And one of my original examples is domestic pushrod V8’s making well over the 400ft-lb with a single coil / distributor.
Bottom line is Todd will eventually go to coil-over-plug technology. He's not ready for that setup just yet. Above any possible performance gains, the increased reliability of individual coils and the elimination of moving parts (rotor) is worth the time / effort.
Todd has been building race motors for the better part of 25 years for all classes of racing, including 1/4 mile.
For many years he was a local celebrity with his home built, 400+hp motorcycle with a supercharged VW engine.
He recently helped finish up a Camaro project – a 900+rwhp street driven turbocharged Camaro. He’s no stranger to big HP cars and what it takes to build / tune a solid drag car.
Not to mention a setup that is good for 1/4 mile is not necessarily ideal for road racing or a daily driver. But I'm sure you already knew that.
If you actually have something useful to add like coil suggestions, dwell settings etc…. please share this information and I’ll pass it on to Todd.
Like I’ve said in many of your threads, I find your project very fascinating and I wish you the best of luck. I don’t want my comments to come off as blatant negativity just because I question some (maybe most) of your methods.
My #1 concern is your safety since I would not dare take your car around a road course at full clip much less a 200+mph run. But, to each his own.
I ask you, no I beg you to please drop it (at least in this thread) unless you have some useful suggestions.
I have no idea what it would take to find out exactly what the differences are between these coils. I think it’s a safe bet the new is rated for a higher output then the earlier unit.
Both the S4 and GT use the same ignition driver, so it's not like they upgraded the whole system.
Brendan, few details you might not be aware of:
1. Todd's ignition problem first reared its ugly head a while ago when his peak boost was much lower. Increasing the dwell time solved the problem.
2. With this dyno session, the ignition miss is already starting at 21psi of manifold pressure.
I was using HP in my example above; I should have been quoting torque.
Intake manifold pressure is not the key factor here, cylinder pressure is.
Manifold pressure does not equal cylinder pressure. This is often confused.
Todd's peak torque is 614lb-ft @ 5500rpm. At this point he is seeing maximum cylinder pressure. This is not at peak boost or RPM. Torque is the best way to gauge cylinder pressure.
A valid comparison would be a similar car producing exactly half that amount of torque (or more), at the same RPM with a single coil.
There are 951’s producing over 300lb-ft of torque on the stock ignition system. Is this ideal? No, many people in the 951 world will be the first to suggest an upgrade of the ignition system for this type of power.
My 81 was making about 325lb-ft of torque @5500rpm when the blower was putting out only 10psi. Now that I’m up to 17 pounds of boost, I’ve surpassed this mark still using a single coil.
I too was having ignition issues until I simply replaced everything with new or known good parts from my 79.
And one of my original examples is domestic pushrod V8’s making well over the 400ft-lb with a single coil / distributor.
Bottom line is Todd will eventually go to coil-over-plug technology. He's not ready for that setup just yet. Above any possible performance gains, the increased reliability of individual coils and the elimination of moving parts (rotor) is worth the time / effort.
Todd has been building race motors for the better part of 25 years for all classes of racing, including 1/4 mile.
For many years he was a local celebrity with his home built, 400+hp motorcycle with a supercharged VW engine.
He recently helped finish up a Camaro project – a 900+rwhp street driven turbocharged Camaro. He’s no stranger to big HP cars and what it takes to build / tune a solid drag car.
Not to mention a setup that is good for 1/4 mile is not necessarily ideal for road racing or a daily driver. But I'm sure you already knew that.
If you actually have something useful to add like coil suggestions, dwell settings etc…. please share this information and I’ll pass it on to Todd.
Like I’ve said in many of your threads, I find your project very fascinating and I wish you the best of luck. I don’t want my comments to come off as blatant negativity just because I question some (maybe most) of your methods.
My #1 concern is your safety since I would not dare take your car around a road course at full clip much less a 200+mph run. But, to each his own.
I ask you, no I beg you to please drop it (at least in this thread) unless you have some useful suggestions.
Last edited by hacker-pschorr; 11-14-2008 at 12:08 PM.
11-14-2008, 10:29 AM
#37
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OR cuting back the electrode, that's a common N2O and Boost trick to prevent flame out. Or indexing the plugs so the electrode faces the intake valve. It will help prevent flame out, however it won't give the best flame front either.
How about just slapping on a bigger coil and MSD?
How about just slapping on a bigger coil and MSD?
11-14-2008, 11:04 AM
#38
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Last night Mike Schmidt (Z) informed me of something neither of us was aware of. Porsche switched to a different coil in 1989 for the GT. My first thought mirrored Mike’s; maybe Bosch simply stopped making the old one, which is not the case. Both are still available.
I have no idea what it would take to find out exactly what the differences are between these coils. I think it’s a safe bet the new is rated for a higher output then the earlier unit.
I have no idea what it would take to find out exactly what the differences are between these coils. I think it’s a safe bet the new is rated for a higher output then the earlier unit.
I have a couple of good used coils I could donate in exchange for a small favor...
11-15-2008, 03:16 PM
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11-16-2008, 07:28 PM
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Hacker-P shot me a some questions about this thread directly but I thought it would be more helpful to join up o the thread to help.
What about timing? What kind of ignition timing are you using?
What type of plugs (heat range)?
Plug wires? (I have some ignition drop out issues with Magnacores….)
I am not a 928 expert but I do know 944s…in 89 the 944 had two different ignition systems. The turbo had the ‘old’ type but the new S2 had a coil set up that required a separate ignition amplifier (located behind the head light).
Nice numbers – it will be interesting to see what you get when it runs clean!!
What about timing? What kind of ignition timing are you using?
What type of plugs (heat range)?
Plug wires? (I have some ignition drop out issues with Magnacores….)
I am not a 928 expert but I do know 944s…in 89 the 944 had two different ignition systems. The turbo had the ‘old’ type but the new S2 had a coil set up that required a separate ignition amplifier (located behind the head light).
Nice numbers – it will be interesting to see what you get when it runs clean!!
11-16-2008, 07:44 PM
#44
Hey Chris! Welcome to the neighborhood!
If some people don't know Chris here, he does some very nice 951 engines with sleeves, among other interesting things. He is very well respected over on the 951 board for many years.
If some people don't know Chris here, he does some very nice 951 engines with sleeves, among other interesting things. He is very well respected over on the 951 board for many years.
11-16-2008, 07:58 PM
#45
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Thanks! I don’t usually let me 944 brothers know that I like 928s…they get all wierded out!
My friend has an early 928 track car, striped with a nice cage and some good suspension set up. Lots of fun to drive on the track! I especially like the throttle response and the engine braking…you don’t get that on a turbo car.
My friend has an early 928 track car, striped with a nice cage and some good suspension set up. Lots of fun to drive on the track! I especially like the throttle response and the engine braking…you don’t get that on a turbo car.