TRExp

Spitfire & GT6 Forum

Who's running a single 40 DCOE?

Moss Motors
AutoShrine Sponsor
AutoShrine Sponsor
AutoShrine Sponsor
AutoShrine Sponsor

GeorgeOhr Nonya Business
Yes, confused, USA   USA
In reply to # 1506531 by clshore In my opinion the 'unequal tract length' theory is a Red Herring.



It runs great as long as you don't stomp it from idle. The problem with this intake is that the accelerator jet squirts straight down 2 and 3.

. Hide banner ads & support this website by becoming a > Gold Supporting Member <
spitlist Avatar
spitlist Joe Curry
Sahuarita, Sahuarita, AZ, USA   USA
In reply to # 1506531 by clshore In my opinion the 'unequal tract length' theory is a Red Herring.

Unless you have actually run one on an 8-port Spitfire head, your assumptions are irrelevant. I have and gave up trying to make all the spark plugs look the same after running a while. I sold the setup and installed a 1.25 inch set of SUs from a Mk3 engine and got immediate results.

Joe

clshore Carter Shore
Beverly Hills, FL, USA   USA
In reply to # 1506548 by spitlist
In reply to # 1506531 by clshore In my opinion the 'unequal tract length' theory is a Red Herring.

Unless you have actually run one on an 8-port Spitfire head, your assumptions are irrelevant. I have and gave up trying to make all the spark plugs look the same after running a while. I sold the setup and installed a 1.25 inch set of SUs from a Mk3 engine and got immediate results.

Joe

So what you are saying is that you tried and failed ('gave up'), but when someone else offers a reasonable explanation and suggestion that you did not try, it's irrelevant.

OK, got it.

. Hide banner ads & support this website by becoming a > Gold Supporting Member <
spitlist Avatar
spitlist Joe Curry
Sahuarita, Sahuarita, AZ, USA   USA
In reply to # 1506549 by clshore
In reply to # 1506548 by spitlist
In reply to # 1506531 by clshore In my opinion the 'unequal tract length' theory is a Red Herring.

Unless you have actually run one on an 8-port Spitfire head, your assumptions are irrelevant. I have and gave up trying to make all the spark plugs look the same after running a while. I sold the setup and installed a 1.25 inch set of SUs from a Mk3 engine and got immediate results.

Joe

So what you are saying is that you tried and failed ('gave up'), but when someone else offers a reasonable explanation and suggestion that you did not try, it's irrelevant.

OK, got it.

No, what I am saying is that you can have all the theories in the world and they mean nothing unless you actually experiment using the "scientific method".

Born Loser Avatar
Born Loser Silver Member Matthew Taylor
Land O Lake, FL, USA   USA
In reply to # 1506545 by GeorgeOhr
In reply to # 1506514 by grumpicus If you've got a pair of 40 DCOEs, but only want to use one, why don't you give up on the idea, sell the pair of them & buy a pair of HS4s + Euro manifold with the proceeds?

Cause I already have those too and don't like them. winking smiley

So you are unhappy with the original HS2's, you are unhappy with the HS4's, and you are unhappy with dual 40 DCOE's. I can promise you will not be happy with a single DCOE either. In fact, I would recommend selling the car.



Matthew
1960 Triumph TR3a
1970 Triumph Spitfire MK 3
2012 Mini Cooper SS Convertible
2018 Jaguar F-Pace

clshore Carter Shore
Beverly Hills, FL, USA   USA
In reply to # 1506551 by spitlist
In reply to # 1506549 by clshore
In reply to # 1506548 by spitlist
In reply to # 1506531 by clshore In my opinion the 'unequal tract length' theory is a Red Herring.

Unless you have actually run one on an 8-port Spitfire head, your assumptions are irrelevant. I have and gave up trying to make all the spark plugs look the same after running a while. I sold the setup and installed a 1.25 inch set of SUs from a Mk3 engine and got immediate results.

Joe

So what you are saying is that you tried and failed ('gave up'), but when someone else offers a reasonable explanation and suggestion that you did not try, it's irrelevant.

OK, got it.

No, what I am saying is that you can have all the theories in the world and they mean nothing unless you actually experiment using the "scientific method".

Interesting term, "scientific method".

As it happens I am an actual Scientist.
Not only do I have a degree that says so, I have about 25 years of success and experience in my field, and am well regarded by my employers and my peers.
It's highly likely that you encounter or interact with work that I have done in your everyday daily life.

The 'Scientific Method' is an approach, often described as a series of steps, which are applied in an iterative fashion.

Question - "Why does my single DCOE fail to deliver expected performance?"
Observation - "The inner and outer plugs indicate substantial mixture differences."
Theory - "The paired intake pulse timing causes asymmetrical overall mixture delivery to the first cylinder and the second cylinder"
Research - "A well known phenomena called 'Charge robbing' is described in literature, on inline 4 cylinder motors where twin carburetor chokes feed adjacent cylinders."
Observation - "Some successful methods used for eliminating or mitigating charge robbing: 1) Manifold that pairs alternate cylinders. 2) A balance tube connecting the two choke plenums."
Experiment1 - "Modify or construct a manifold that pairs alternate cylinders, capture performance result data"
Experiment2 - "Modify or construct a manifold that implements a balance tube, capture performance result data"
Analysis - "Compare baseline pre-modification performance data with results from Experiments, draw conclusions"
If necessary, continue with Scientific Method, repeating steps.

Pragmatically, to me, Experiment1 is more work, it's not likely that the manifold in question can be easily modified, so construction is the alternative.
Experiment2 is easier, could be done with hand tools and some inexpensive hardware in an afternoon.

Note that one of the fundamental steps is 'theory'.
Without a 'theory' about what is occurring, it's difficult to even consider an 'experiment'.
What item do you change? What do you measure?

Your 'explanation' is also a theory, that the mixture issue was due to different runner lengths/shapes.
Note that in my post #14, I also provided Question, Observation, Theory, Research, AND described a proposed Experiment.
So which of us is using the "scientific method"?

Of course, I don't have a single DCOE manifold lying around to modify, so I cannot conduct the experiment.
You sold yours, so neither do you, so all you have is a theory as well.

But the OP has one.
How about it George, ready to conduct an experiment?



Edited 2 time(s). Last edit at 2018-01-08 04:46 PM by clshore.

Doug in Vegas Avatar
Doug in Vegas Douglas D
Las Vegas, NV, USA   USA
I know someone who's an actual scientist.

He's never opened the hood on his car.

He leaves that to mechanics.

. Hide banner ads & support this website by becoming a > Gold Supporting Member <
spitlist Avatar
spitlist Joe Curry
Sahuarita, Sahuarita, AZ, USA   USA
In reply to # 1506560 by clshore
In reply to # 1506551 by spitlist
In reply to # 1506549 by clshore
In reply to # 1506548 by spitlist
In reply to # 1506531 by clshore In my opinion the 'unequal tract length' theory is a Red Herring.

Unless you have actually run one on an 8-port Spitfire head, your assumptions are irrelevant. I have and gave up trying to make all the spark plugs look the same after running a while. I sold the setup and installed a 1.25 inch set of SUs from a Mk3 engine and got immediate results.

Joe

So what you are saying is that you tried and failed ('gave up'), but when someone else offers a reasonable explanation and suggestion that you did not try, it's irrelevant.

OK, got it.

No, what I am saying is that you can have all the theories in the world and they mean nothing unless you actually experiment using the "scientific method".

Interesting term, "scientific method".

As it happens I am an actual Scientist.
Not only do I have a degree that says so, I have about 25 years of success and experience in my field, and am well regarded by my employers and my peers.
It's highly likely that you encounter or interact with work that I have done in your everyday daily life.

The 'Scientific Method' is an approach, often described as a series of steps, which are applied in an iterative fashion.

Question - "Why does my single DCOE fail to deliver expected performance?"
Observation - "The inner and outer plugs indicate substantial mixture differences."
Theory - "The paired intake pulse timing causes asymmetrical overall mixture delivery to the first cylinder and the second cylinder"
Research - "A well known phenomena called 'Charge robbing' is described in literature, on inline 4 cylinder motors where twin carburetor chokes feed adjacent cylinders."
Observation - "Some successful methods used for eliminating or mitigating charge robbing: 1) Manifold that pairs alternate cylinders. 2) A balance tube connecting the two choke plenums."
Experiment1 - "Modify or construct a manifold that pairs alternate cylinders, capture performance result data"
Experiment2 - "Modify or construct a manifold that implements a balance tube, capture performance result data"
Analysis - "Compare baseline pre-modification performance data with results from Experiments, draw conclusions"
If necessary, continue with Scientific Method, repeating steps.

Pragmatically, to me, Experiment1 is more work, it's not likely that the manifold in question can be easily modified, so construction is the alternative.
Experiment2 is easier, could be done with hand tools and some inexpensive hardware in an afternoon.

Note that one of the fundamental steps is 'theory'.
Without a 'theory' about what is occurring, it's difficult to even consider an 'experiment'.
What item do you change? What do you measure?

Your 'explanation' is also a theory, that the mixture issue was due to different runner lengths/shapes.
Note that in my post #14, I also provided Question, Observation, Theory, Research, AND described a proposed Experiment.
So which of us is using the "scientific method"?

Of course, I don't have a single DCOE manifold lying around to modify, so I cannot conduct the experiment.
You sold yours, so neither do you, so all you have is a theory as well.

But the OP has one.
How about it George, ready to conduct an experiment?

Except that I did actually test the theory and concluded with actual observation that the fault was with the unequal length runners.

GeorgeOhr Nonya Business
Yes, confused, USA   USA




.



Edited 2 time(s). Last edit at 2018-01-08 08:15 PM by GeorgeOhr.

. Hide banner ads & support this website by becoming a > Gold Supporting Member <
GeorgeOhr Nonya Business
Yes, confused, USA   USA
In reply to # 1506577 by spitlist
In reply to # 1506560 by clshore
In reply to # 1506551 by spitlist
In reply to # 1506549 by clshore
In reply to # 1506548 by spitlist
In reply to # 1506531 by clshore In my opinion the 'unequal tract length' theory is a Red Herring.

Unless you have actually run one on an 8-port Spitfire head, your assumptions are irrelevant. I have and gave up trying to make all the spark plugs look the same after running a while. I sold the setup and installed a 1.25 inch set of SUs from a Mk3 engine and got immediate results.

Joe

So what you are saying is that you tried and failed ('gave up'), but when someone else offers a reasonable explanation and suggestion that you did not try, it's irrelevant.

OK, got it.

No, what I am saying is that you can have all the theories in the world and they mean nothing unless you actually experiment using the "scientific method".

Interesting term, "scientific method".

As it happens I am an actual Scientist.
Not only do I have a degree that says so, I have about 25 years of success and experience in my field, and am well regarded by my employers and my peers.
It's highly likely that you encounter or interact with work that I have done in your everyday daily life.

The 'Scientific Method' is an approach, often described as a series of steps, which are applied in an iterative fashion.

Question - "Why does my single DCOE fail to deliver expected performance?"
Observation - "The inner and outer plugs indicate substantial mixture differences."
Theory - "The paired intake pulse timing causes asymmetrical overall mixture delivery to the first cylinder and the second cylinder"
Research - "A well known phenomena called 'Charge robbing' is described in literature, on inline 4 cylinder motors where twin carburetor chokes feed adjacent cylinders."
Observation - "Some successful methods used for eliminating or mitigating charge robbing: 1) Manifold that pairs alternate cylinders. 2) A balance tube connecting the two choke plenums."
Experiment1 - "Modify or construct a manifold that pairs alternate cylinders, capture performance result data"
Experiment2 - "Modify or construct a manifold that implements a balance tube, capture performance result data"
Analysis - "Compare baseline pre-modification performance data with results from Experiments, draw conclusions"
If necessary, continue with Scientific Method, repeating steps.

Pragmatically, to me, Experiment1 is more work, it's not likely that the manifold in question can be easily modified, so construction is the alternative.
Experiment2 is easier, could be done with hand tools and some inexpensive hardware in an afternoon.

Note that one of the fundamental steps is 'theory'.
Without a 'theory' about what is occurring, it's difficult to even consider an 'experiment'.
What item do you change? What do you measure?

Your 'explanation' is also a theory, that the mixture issue was due to different runner lengths/shapes.
Note that in my post #14, I also provided Question, Observation, Theory, Research, AND described a proposed Experiment.
So which of us is using the "scientific method"?

Of course, I don't have a single DCOE manifold lying around to modify, so I cannot conduct the experiment.
You sold yours, so neither do you, so all you have is a theory as well.

But the OP has one.
How about it George, ready to conduct an experiment?

Except that I did actually test the theory and concluded with actual observation that the fault was with the unequal length runners.


A little of track here guys.

Spitfirejoe Avatar
Spitfirejoe Joe Guinan
Fremont, NE, USA   USA
1980 Triumph Spitfire 1500 "The Phoenix"
It's winter. And a bad winter so far. We're gonna have pissing matches. Not that this is "OK", just a fact of live on forums.



Joe Guinan
Fremont, Nebraska

GeorgeOhr Nonya Business
Yes, confused, USA   USA
In reply to # 1506607 by Spitfirejoe It's winter. And a bad winter so far. We're gonna have pissing matches. Not that this is "OK", just a fact of live on forums.


It used to not be that way in most LBC forums a few years back. It's still WAY off topic and doesn't help in the least bit. I've been surprised as of late of some of the non sequitur replies I've been seeing in some threads. Sometimes I can't help but wonder if it's my wife replying secretly.

I ask her what time she's gonna be home.....and instead I get read a list of everything she has to do before she leaves.....confused smiley

KRGS 68 Spitfire Rene Gimenez
Valencia, CA, USA   USA
This a Lynx manifold from Australia and the carb is an SK 45 sidedraft (Japanese DCOE copy). Took me a couple of weekends tinkering with jets, playing with plugs, and running around my local industrial complex to dial it in. Pulls from 1800 to 6000 rpm (haven't run it higher than that). I originally had the Canon single sidedraft manifold where you can see the unequal length runners, and this delivers the low end. Very happy camper, and I've tuned motors from Formula Fords, carbureted Super Vees to Cosworth BDA's


Attachments:
IMG_1312 4.JPG    38.6 KB
IMG_1312 4.JPG

IMG_1310.JPG    46.3 KB
Sign In or Register to view this photo
grumpicus Steve Jackson
Leicester, Leicestershire, UK   GBR
The Lynx manifold used to be available in the UK - sold by SAH/Triumphtune/Moss as I recall. The idea is that it equalises the intervals between induction pulses at each barrel of the carb, but obviously means the inlet tracts are curved (tortuous?) and maybe have different overall lengths. Possibly the equalising of the time intervals between induction pulses has a more beneficial effect than the negative effects of more indirect paths between carb & head. It might be interesting to see how this sort of setup would work with twin HS4s, and compare that with the factory twin HS4 setup.

Yes, it's winter, the weather prevents us from playing with our toys, so we vent our frustrations online.....added to that, we're all getting older, and maybe just a little bit grumpier.... eye rolling smiley

Born Loser Avatar
Born Loser Silver Member Matthew Taylor
Land O Lake, FL, USA   USA
In reply to # 1506607 by Spitfirejoe It's winter. And a bad winter so far. We're gonna have pissing matches. Not that this is "OK", just a fact of live on forums.

Y'all know Carter is in 70 and 80 degree weather right...
Hes just like coffee - an acquired taste! Have a few more cups...



Matthew
1960 Triumph TR3a
1970 Triumph Spitfire MK 3
2012 Mini Cooper SS Convertible
2018 Jaguar F-Pace

. Hide banner ads & support this website by becoming a > Gold Supporting Member <

To add your reply, or post your own questions




Registration is FREE and takes less than a minute!


Having trouble posting or changing forum settings?
Read the Forum Help (FAQ) or contact the webmaster