1st Dyno run complete - analysis help
Nordschleife Master
Joined: Jan 2009
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From: MA
- H-Pipe= 16.4 X-Pipe= 65.5 distance behind end of Primary Tube ends
What this formula in Pipemax is suggesting is that it would be better to have an H up front and an X approximately 49” behind that
They are measured from the end of the primary tubes (four per side) where the pulses from cylinders start to combine. Since different headers have different length collectors, it only makes sense to give the measurement from the end of the primary tubes.
Whether it's an X or H, PipeMax is mainly telling you to _not_ put it at 24.5, 49.1, 98.2, or 196.4 inches from the primary tube ends.
If you put in both H upstream and X downstream, the downstream X and it's location doesn't really matter for power. The existence of the X after H does matter to exhaust sound, though.
Nordschleife Master
Joined: Apr 2003
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From: Abbotsford B.C.
Colin, can you post the 350 rwhp dyno which uses your cams?
Of course, the owner of the car can remain anonymous
Or, is this story I've heard simply not true? If so, I apologize.
This the first time that I'm aware of that results of your cams have been posted in a thread, and we need some help and assurance that these cams will work with an engine.
Of course, the owner of the car can remain anonymous
Or, is this story I've heard simply not true? If so, I apologize.
This the first time that I'm aware of that results of your cams have been posted in a thread, and we need some help and assurance that these cams will work with an engine.
Some are dwelling on the camshafts being too large for the engine. These cams being too large are not going to cause the car to put a graph out as it has.
Jeff Mohler (speedtoys) claimed with the Victor SC he had that he recorded an estimated minimum BHP gain of 70bhp from the installation of the camshafts.
I've dynoed a few cars with the (most with tri-flow) one without. Stock S4 put down 330rwhp, Terry's GT put down 350RWHP. I've got another S4 here as well with cams and headers and once I fix his clutch (slipping badly) I will put it on the dyno and post up a fresh chart if I can talk the owner into letting me do that.
I feel that there is either something else amiss (misaligned timing ring?) or that the dyno used was simply not accurate. This is why I have asked for some real world measurements being done by on the street tests before we continue to try and find the problem at hand.
Rennlist Member
Joined: Feb 2006
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From: Chicago Bears
It's been posted and shared here on RL numerous times. The owner is here on RL as well username is TerryGT. I had also sent those graphs to Martin as well.
Some are dwelling on the camshafts being too large for the engine. These cams being too large are not going to cause the car to put a graph out as it has.
Jeff Mohler (speedtoys) claimed with the Victor SC he had that he recorded an estimated minimum BHP gain of 70bhp from the installation of the camshafts.
I've dynoed a few cars with the (most with tri-flow) one without. Stock S4 put down 330rwhp, Terry's GT put down 350RWHP. I've got another S4 here as well with cams and headers and once I fix his clutch (slipping badly) I will put it on the dyno and post up a fresh chart if I can talk the owner into letting me do that.
I feel that there is either something else amiss (misaligned timing ring?) or that the dyno used was simply not accurate. This is why I have asked for some real world measurements being done by on the street tests before we continue to try and find the problem at hand.
Some are dwelling on the camshafts being too large for the engine. These cams being too large are not going to cause the car to put a graph out as it has.
Jeff Mohler (speedtoys) claimed with the Victor SC he had that he recorded an estimated minimum BHP gain of 70bhp from the installation of the camshafts.
I've dynoed a few cars with the (most with tri-flow) one without. Stock S4 put down 330rwhp, Terry's GT put down 350RWHP. I've got another S4 here as well with cams and headers and once I fix his clutch (slipping badly) I will put it on the dyno and post up a fresh chart if I can talk the owner into letting me do that.
I feel that there is either something else amiss (misaligned timing ring?) or that the dyno used was simply not accurate. This is why I have asked for some real world measurements being done by on the street tests before we continue to try and find the problem at hand.
Thread Starter
Pro
Joined: May 2011
Posts: 638
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From: Edinburgh, Scotland
Blocked exhaust theory turned out to be wrong,
I have changed the system for a twin 2.5” with H at the front and X at the back and nice Magnaflow boxes.
It it does sound lovely but certainly not released a chunk of power.
Next change is to swap the inlet manifold for a completely standard version as a control point to eliminate the modified version.
Warm compression check to be carried out beforehand
I have changed the system for a twin 2.5” with H at the front and X at the back and nice Magnaflow boxes.
It it does sound lovely but certainly not released a chunk of power.
Next change is to swap the inlet manifold for a completely standard version as a control point to eliminate the modified version.
Warm compression check to be carried out beforehand
Rennlist Member
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From: Oman
Marti,
Going back to one of Colin's comments- if you have a timing light, try checking the timing against the operating cell value in ST2. Those timing rings have been known to slip so no harm in eliminating that one from the line of enquiry bummer that it is.
Going back to one of Colin's comments- if you have a timing light, try checking the timing against the operating cell value in ST2. Those timing rings have been known to slip so no harm in eliminating that one from the line of enquiry bummer that it is.
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From: Mostly in my workshop located in Sweden.
Åke
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Joined: Feb 2006
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From: Chicago Bears
I would recommend going back to stock camshafts, S4 or GT.
There's not much info on these new cams to draw any conclusions one way or the other.
The stock cams have well known, predictable behavior, something you need at this point, including testing a new intake.
There's not much info on these new cams to draw any conclusions one way or the other.
The stock cams have well known, predictable behavior, something you need at this point, including testing a new intake.
Thread Starter
Pro
Joined: May 2011
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From: Edinburgh, Scotland
The modified intake is now a key concern although I need to check this timing ring which I am not sure what it is at present
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Nordschleife Master
Joined: Jan 2009
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From: MA
That was clear from the original dyno graph already.
Nordschleife Master
Joined: Jan 2009
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From: MA
If it were just a flow restriction outside the part of the system where pulses matter, then you’d see the engine hitting a wall at some power level and torque curve nosediving. You don’t see that with your engine. Because of this, I am guessing (and it’s just a guess) that the problem is between the throttle body and the X-pipe. I am guessing that the throttle body or upstream components are not a restriction and, similarly, nothing downstream of the X-pipe is a restriction either. Dual 2” pipes would flow your current hp, in my opinion.
Nordschleife Master
Joined: Jan 2009
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From: MA
...it is very unlikely that you have an exhaust blockage. First, what's causing the blockage if you have no cats? Second, you'd expect exhaust blockage to cause the power curve to flatten at certain rpm and the torque curve to nosedive. Instead, you see torque curve holding up and the power curve just climbing even at high rpms. This is not a situation where I'd diagnose an exhaust restriction.
Thread Starter
Pro
Joined: May 2011
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From: Edinburgh, Scotland
No issue though, the performance exhaust system removes another blocker from producing more hp