Holber race car gets a new engine. Progress Report
10-14-2008, 03:42 PM
#586
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What I am thinking is that this artifact is revealing something about the underlying fuel control system whether digital, analog or both. I am guessing there is a "handoff" there from one system or map to another.
Just a guess. But it is interesting that it conforms with your observations about a transition at 5000 rpms.
Edit: On the pics you just posted the transition is there too (top pic). The curve goes from concave upward to concave downward. That is a transition from a positive second derivative to a negative second derivative. The first derivative is the slope; the second derivative gives you the instantaneous rate of change of the slope. The sign of that change (neg or positive) lets you know how the curve is trending. A point of inflection is where the sign goes from neg to pos or vice versa.
10-14-2008, 03:50 PM
#587
Three Wheelin'
John,
That's what I was wondering about. Base map is off, but after adaptation is acceptable. Adaptation table, constructed in closed loop, is also applicable to the open loop map areas.
That's what I was wondering about. Base map is off, but after adaptation is acceptable. Adaptation table, constructed in closed loop, is also applicable to the open loop map areas.
Hi Mark,
Yes I posted, and then tought better of it, as I can't relate this issue with "adaptation", but there does have to be a link, doesn't there ?
I can only assume that the tune when loop is "open" is somewhat off, until the adaptation is re-established. It will be re-established each time you go to cruise between your WOT runs. The adaptation is still applied when you go off the O2 loop.
What type of FPR are you using ? Is it a RRFPR ? I understand it is adjustable as well...
Yes I posted, and then tought better of it, as I can't relate this issue with "adaptation", but there does have to be a link, doesn't there ?
I can only assume that the tune when loop is "open" is somewhat off, until the adaptation is re-established. It will be re-established each time you go to cruise between your WOT runs. The adaptation is still applied when you go off the O2 loop.
What type of FPR are you using ? Is it a RRFPR ? I understand it is adjustable as well...
10-14-2008, 04:19 PM
#588
Rennlist Member
10-14-2008, 05:10 PM
#590
Three Wheelin'
I can try to do the experiement without the o2 sensor connected as well if that would mean anything. I guess, if im reading you right, maybe the fuel mixture is way rich during the stumbling at high rpm .
The plugs look much better since ive pulled out the Fuel pressure.
again, I would guess that im in the 11:5 to 12:1 range now, but certanly better than 11.1:1 now due to pulling out some fuel pressure after the last dyno.
Ill pull a plug and show you.
mk
The plugs look much better since ive pulled out the Fuel pressure.
again, I would guess that im in the 11:5 to 12:1 range now, but certanly better than 11.1:1 now due to pulling out some fuel pressure after the last dyno.
Ill pull a plug and show you.
mk
Your plugs might be a bit too cold too, but plug reading will tell that. One thing to remember on the big cube motors vs the high power boosted motors is that the big cube motors don't have much more combustion heat or cylinder pressure than a stock motor. A little more due to higher compression ratio, but that is all. The situation with your motor is that the VE isn't very high. The dynamic compression ratio at higher RPMs is low. The combustion temps are likely lower in comparison to even a stock GT. Running such rich mixture isn't needed for combustion chamber temperature control and is a detriment for sharp running and throttle response. As the mixture is leaned, spark timing may need refined. Just an opinion...
https://rennlist.com/forums/attachme...1&d=1224014749
https://rennlist.com/forums/attachme...1&d=1224014528
Last edited by Louie928; 06-13-2013 at 05:13 PM.
10-15-2008, 12:43 PM
#591
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Originally Posted by mark kibort
what am i looking for here? It just pulled me to a page with a random 928 dyno result. are you looking for an inflection pont at 5,000rpm? If so, i havent seen that on any of the 100 dyno pulls on my car!
If you follow the 5000 rpm "line" up to where the hp curve crosses it you can see the curve goes from an arc to flat then back to an arc.
What I am thinking is that this artifact is revealing something about the underlying fuel control system whether digital, analog or both. I am guessing there is a "handoff" there from one system or map to another.
Just a guess. But it is interesting that it conforms with your observations about a transition at 5000 rpms.
Edit: On the pics you just posted the transition is there too (top pic). The curve goes from concave upward to concave downward. That is a transition from a positive second derivative to a negative second derivative. The first derivative is the slope; the second derivative gives you the instantaneous rate of change of the slope. The sign of that change (neg or positive) lets you know how the curve is trending. A point of inflection is where the sign goes from neg to pos or vice versa.
What I am thinking is that this artifact is revealing something about the underlying fuel control system whether digital, analog or both. I am guessing there is a "handoff" there from one system or map to another.
Just a guess. But it is interesting that it conforms with your observations about a transition at 5000 rpms.
Edit: On the pics you just posted the transition is there too (top pic). The curve goes from concave upward to concave downward. That is a transition from a positive second derivative to a negative second derivative. The first derivative is the slope; the second derivative gives you the instantaneous rate of change of the slope. The sign of that change (neg or positive) lets you know how the curve is trending. A point of inflection is where the sign goes from neg to pos or vice versa.
I was looking at some of the distributor advance curves for the Matra Djet 5S and in distributor rpm the Sierra crossflow engine slope flatlines at 2500 or 5000 rpm crank speed. This makes me think the ignition advance (curve) lookup tables for the Porsche 928 S4 are involved and adaptation in general is noticed at the beginning of the 5000 to 6000 rpm range because of a probable correspondance in max advance curve slopes between that of the Matra and Porsche engines. It is difficult to know what tables are being adapted.
That is one nice thing about saving detailed engine manuals pre-fuel injection. The information isn't so proprietary.
Hard to say for sure if this is really the root of the 5000 rpm onset, of course.
Last edited by Kevin Johnson; 10-15-2008 at 02:38 PM.
10-15-2008, 04:19 PM
#592
Rennlist Member
Thread Starter
my plugs are not caked with black, they are clean and dry and only have a black stain rather than the black carbon build up as before. It depends when i pull them, as to what they look like. after a race, they look very normal.
I suspect, air fuel ratios are in the 12:1 range now.
mk
I suspect, air fuel ratios are in the 12:1 range now.
mk
Here is a couple pics of one of my plugs (cyl #6). They have about 6000 miles on them. The gap is 0.045". The gap was widened to improve low throttle opening, low load, roughness. They are WR6DC. Cruise mixture is around 15.5:1 and full throttle mixture is in the 13 to 13.5:1 range. You can't see it to well, but there is no soft flaky carbon around the base. Admittedly, these plugs have little WOT use except for one DE day recently. It's just a guess, but I'd postulate that your base map mixture is too rich and especially too rich in the 5000 - 6000 RPM range before mixture adaptation takes place. After adaptation, the mixture is lean enough to run smoothly. The WOT enrichment map isn't needed at all, and you still have it functioning. I put zeroes in the WOT map and even then have to lean out the base map in the upper load/rpm area.
Your plugs might be a bit too cold too, but plug reading will tell that. One thing to remember on the big cube motors vs the high power boosted motors is that the big cube motors don't have much more combustion heat or cylinder pressure than a stock motor. A little more due to higher compression ratio, but that is all. The situation with your motor is that the VE isn't very high. The dynamic compression ratio at higher RPMs is low. The combustion temps are likely lower in comparison to even a stock GT. Running such rich mixture isn't needed for combustion chamber temperature control and is a detriment for sharp running and throttle response. As the mixture is leaned, spark timing may need refined. Just an opinion...
https://rennlist.com/forums/attachme...1&d=1224014749
https://rennlist.com/forums/attachme...1&d=1224014528
Your plugs might be a bit too cold too, but plug reading will tell that. One thing to remember on the big cube motors vs the high power boosted motors is that the big cube motors don't have much more combustion heat or cylinder pressure than a stock motor. A little more due to higher compression ratio, but that is all. The situation with your motor is that the VE isn't very high. The dynamic compression ratio at higher RPMs is low. The combustion temps are likely lower in comparison to even a stock GT. Running such rich mixture isn't needed for combustion chamber temperature control and is a detriment for sharp running and throttle response. As the mixture is leaned, spark timing may need refined. Just an opinion...
https://rennlist.com/forums/attachme...1&d=1224014749
https://rennlist.com/forums/attachme...1&d=1224014528
10-18-2008, 08:17 PM
#593
Rennlist Member
Thread Starter
Here are the plugs after about 30mins of 60-100 redline runs on the hyway, and lots of full throttle brake drags to super heat the brakes for bedding. (new brakes installed before the next race)
the deep thick black rim is now just a black stain and the electrode is a little white
the deep thick black rim is now just a black stain and the electrode is a little white
10-18-2008, 08:49 PM
#594
Three Wheelin'
Here are the plugs after about 30mins of 60-100 redline runs on the hyway, and lots of full throttle brake drags to super heat the brakes for bedding. (new brakes installed before the next race)
the deep thick black rim is now just a black stain and the electrode is a little white
the deep thick black rim is now just a black stain and the electrode is a little white
10-18-2008, 08:56 PM
#595
Rennlist Member
Thread Starter
thanks. they were a lot more brown black looking over all, but i was doing some fuel pressure tests at idle for a few mins befoe i pulled them. this time was all WOT runs . the fuel pressure is down a few psi now vs the dyno run and it seems to like it. however, its so rich at idle that the AFM doesnt hunt until i am cruising on the street. exhaust pipe has a nice coating of black carbon.
off to the races next weekend.
mk
off to the races next weekend.
mk
10-18-2008, 09:10 PM
#596
Three Wheelin'
perhaps a repost or late.... sorry for that.... i installed new belt and tensioner and the timing marks are perfect in line... just had to pull the belt hard by hand ... till last cam.... will see what i does after miles.. 
is there HP gain from advance or retard timing or only to be tested on a dyno ?
is there HP gain from advance or retard timing or only to be tested on a dyno ?
10-18-2008, 09:32 PM
#597
Three Wheelin'
perhaps a repost or late.... sorry for that.... i installed new belt and tensioner and the timing marks are perfect in line... just had to pull the belt hard by hand ... till last cam.... will see what i does after miles..
is there HP gain from advance or retard timing or only to be tested on a dyno ?
is there HP gain from advance or retard timing or only to be tested on a dyno ?
10-18-2008, 09:39 PM
#598
Three Wheelin'
Cam advance will help on the low end and retarded cams give help on the high end with mid range not affected much one way or the other. It kind of depends on how you will use the car. Stock timing is a really good compromise while if you are going to be track only with best power above 4500 you might want 5 crank degrees retard. It's not going to make a huge differences either way. To check how your side to side cam timing is, take a compression reading with the engine hot. The side that is lower in compression can be helped to be more equal by advancing the cams on that side. Intake valve closes sooner in the compression cycle.
06-26-2009, 06:50 AM
#599
Nordschleife Master
simulation, a stab in the dark
MK -- Please find your latest stroker dyno charts. TV
Assumptions. I intentionally assumed a lot of things that produce a lot of low-end torque.
What's the stroke? I am assuming 4.06"
What's the bore? I am assuming stock
I am assuming stock heads with stock valves and no porting
I am assuming 11:1 compression ratio
I am assuming S3 cam installed 6.5 degrees retarded
I am assuming stock S4 springs installed to 10 lbf higher load with shims
What's the primary header runner diameter? I am assuming 1.625"
Are your headers stepped? I am assuming no, constant diameter pipe
What's the primary runner length for the headers? I am assuming 40"
How long is the header collector? I am assuming 6"
I am assuming no taper in the collector
What's the diameter of the header collector? I am assuming 2.5"
I am assuming you run flappy open
I am assuming that the intake runners are about 10" long and not tapered
I am assuming 93 octane gas
I am assuming 12.5 AFR
Results:
Intake valves are being tossed above about 7000 rpm
Exhaust valves are being tossed above about 7200 rpm
Detonation most likely at 3800 rpm
Peak crank torque 435 ft-lbf at 3800 rpm
Peak crank power 365 hp at 4850
Repost the dyno graphs and let's start modifying the measurable parameters to be more accurate and then use the non-measurable parameters to make the simulation dyno graph fit your actual dyno graph. This will then serve as a baseline for cam experiments.
Assumptions. I intentionally assumed a lot of things that produce a lot of low-end torque.
What's the stroke? I am assuming 4.06"
What's the bore? I am assuming stock
I am assuming stock heads with stock valves and no porting
I am assuming 11:1 compression ratio
I am assuming S3 cam installed 6.5 degrees retarded
I am assuming stock S4 springs installed to 10 lbf higher load with shims
What's the primary header runner diameter? I am assuming 1.625"
Are your headers stepped? I am assuming no, constant diameter pipe
What's the primary runner length for the headers? I am assuming 40"
How long is the header collector? I am assuming 6"
I am assuming no taper in the collector
What's the diameter of the header collector? I am assuming 2.5"
I am assuming you run flappy open
I am assuming that the intake runners are about 10" long and not tapered
I am assuming 93 octane gas
I am assuming 12.5 AFR
Results:
Intake valves are being tossed above about 7000 rpm
Exhaust valves are being tossed above about 7200 rpm
Detonation most likely at 3800 rpm
Peak crank torque 435 ft-lbf at 3800 rpm
Peak crank power 365 hp at 4850
Repost the dyno graphs and let's start modifying the measurable parameters to be more accurate and then use the non-measurable parameters to make the simulation dyno graph fit your actual dyno graph. This will then serve as a baseline for cam experiments.
Originally Posted by MK
Torque was 420 at the rear wheels, while the hp was at 365. (I think someone predicted this!)
More of the good news was that the mixture was set pretty good from the start, and all we had to do was richen it up by .5 turn on the RRFR, which drowned the motor at 10:1, and then back it off by 1/4 turn to reach the range of 13:1 down to 11:1 at the top. So, good that it is safe and bad that its a little fat up top.
I had some good indication of 400rwhp, from 60-80mph, but hadnt taken it to 6000rpm to see what the next half of the 60-100 test would look like. Well, on the way home, still, 1.9 seconds 60-80, but the next 20mph to 100mph was 2.5 seconds. Not much faster than my fastest runs with the stock holbert car of 3.0 seconds. Actually, Im starting to really like the freeway dyno. Its pretty cheap and reasonably accurate. So the car is at 4.5 sec, 60-100mph. Not bad for only a stroke and slight bore increase.
Here are the dyno runs. The progression started out with 1.5 turns rich. It was kind of lean. we turned it up by .5 a turn. that buried the fuel ratio in the rich range. So we leaned it up by .25 a turn. AND, if you noticed, we started the dyno run at a lower rpm, as the fuel ratio seems to require about 400rpm to stablize, no matter what the fuel setting. (going from closed loop to open loop.)
More of the good news was that the mixture was set pretty good from the start, and all we had to do was richen it up by .5 turn on the RRFR, which drowned the motor at 10:1, and then back it off by 1/4 turn to reach the range of 13:1 down to 11:1 at the top. So, good that it is safe and bad that its a little fat up top.
I had some good indication of 400rwhp, from 60-80mph, but hadnt taken it to 6000rpm to see what the next half of the 60-100 test would look like. Well, on the way home, still, 1.9 seconds 60-80, but the next 20mph to 100mph was 2.5 seconds. Not much faster than my fastest runs with the stock holbert car of 3.0 seconds. Actually, Im starting to really like the freeway dyno. Its pretty cheap and reasonably accurate. So the car is at 4.5 sec, 60-100mph. Not bad for only a stroke and slight bore increase.
Here are the dyno runs. The progression started out with 1.5 turns rich. It was kind of lean. we turned it up by .5 a turn. that buried the fuel ratio in the rich range. So we leaned it up by .25 a turn. AND, if you noticed, we started the dyno run at a lower rpm, as the fuel ratio seems to require about 400rpm to stablize, no matter what the fuel setting. (going from closed loop to open loop.)
06-26-2009, 04:19 PM
#600
Rennlist Member
Thread Starter
I think you are ok on the header specs. cams are set at 0 from spec. (original holbert cams were advanced around 5-6 degrees) I started there and moved them to 0 based on that huge discussion with Porken and the original tool test results and the technique I was using with my dial indicator.
Here is the dyno run with the best pull after a slight leaning of the mixture to around 11 to 11.5:1
Your assumptions:
What's the stroke? I am assuming 4.06" -more like 3.7"
What's the bore? I am assuming stock - 103.7mm
I am assuming stock heads with stock valves and no porting - correct
I am assuming 11:1 compression ratio - yes
I am assuming S3 cam installed 6.5 degrees retarded - set at 0 stock spec
I am assuming stock S4 springs installed to 10 lbf higher load with shims - no shims. springs look a little tougher than stock.
What's the primary header runner diameter? I am assuming 1.625" - yes
Are your headers stepped? I am assuming no, constant diameter pipe -constant
What's the primary runner length for the headers? I am assuming 40" - dont know.
How long is the header collector? I am assuming 6"- dont know
I am assuming no taper in the collector - a necked down venturi for the y pipe joining the two sides. Devek design.
What's the diameter of the header collector? I am assuming 2.5"- Yes
I am assuming you run flappy open - Yes
I am assuming that the intake runners are about 10" long and not tapered -dont know
I am assuming 93 octane gas - 91 octane
I am assuming 12.5 AFR more like 11.5, but acts a little leaner based on off track examination at the track. safe for sure.
Here is the dyno run with the best pull after a slight leaning of the mixture to around 11 to 11.5:1
Your assumptions:
What's the stroke? I am assuming 4.06" -more like 3.7"
What's the bore? I am assuming stock - 103.7mm
I am assuming stock heads with stock valves and no porting - correct
I am assuming 11:1 compression ratio - yes
I am assuming S3 cam installed 6.5 degrees retarded - set at 0 stock spec
I am assuming stock S4 springs installed to 10 lbf higher load with shims - no shims. springs look a little tougher than stock.
What's the primary header runner diameter? I am assuming 1.625" - yes
Are your headers stepped? I am assuming no, constant diameter pipe -constant
What's the primary runner length for the headers? I am assuming 40" - dont know.
How long is the header collector? I am assuming 6"- dont know
I am assuming no taper in the collector - a necked down venturi for the y pipe joining the two sides. Devek design.
What's the diameter of the header collector? I am assuming 2.5"- Yes
I am assuming you run flappy open - Yes
I am assuming that the intake runners are about 10" long and not tapered -dont know
I am assuming 93 octane gas - 91 octane
I am assuming 12.5 AFR more like 11.5, but acts a little leaner based on off track examination at the track. safe for sure.