Diskussion zu meiner Leistungskurve

[darock]

@headguy

Its not about Robert's Engine ... we are talking about mine ... I have a Newman cam which is supposed to be a good one.

My cylinder head is optimized based on what I have read in your book! My work can't be really bad because 220+NM is absolutely not bad for a dual carb engine!

so what can also cause that extreme dip of the torque curve after the engine reaches peak HP? I am sure you know that.

@Jörg

der Knick bei 2300 ist eindeutig Klopfen gewesen, das wird noch behoben, da weiss ich ja fix woher es kommt ...

Deine maximale Leistung liegt auch deutlich über meiner an ... Also ist vielleicht doch die Dual Vergaser Anlage bzw die miserable Ansaugbrücke schuld? (meine ist auch bearbeitet)

Auspuff ist der originale Krümmer (Übergänge bearbeitet) und eine Falcon GT.

Bernhard

[Gyula]

Hi!

Ich würde mal gerne eine Kurve sehen, die mit einer 260 er Newmann bis min. 5500 rpm geht um zu sehen, wie steil dort die Kurven abfllen.....

Die Angaben von Jörg irritieren mich im Vergleich etwas, da bei ihm die Werte für max. Drehmoment und max. Leistung doch deutlich höher liegen.
Ohne bearbeitetem ZK, Verdichtung 9,5:1?
Und wie sieht es mit der Zündkurve aus?
Wo ist bei dir, Jörg, das Maximum?
Ich erinnere mich, gelesen zu haben, dass mit der 260-er Newman und einer Verdichtung von 9,5:1 die selbe Kurve gefahren wird, wie mit dem 123 PS PI, also bis 38°........

Es wird hier auch mit den Vergasern argumentiert.
Aber verschiedene TR-Freun.de betonen immmer wieder, dass die Leistungsgrenzen von zwei ZS oder SU HS6 beim TR6 noch lange nicht ausgeschöpft seien........

Es werde licht im Dunklen.........

Gyula

[gelpont19]

Bernhard - fährste noch mit den Stromberg rum - oder haste schon andere ? In deinem Video mit der KH Achse meine ich ZS gesehen zu haben.
Die ZS sind bei mir auch oben rum zu mager, konnte bisher keine anderen Düsen auftreiben, die fetter durchlassen, die jetzigen sind am Anschlag. Da die ZS eh ne Revision brauchen, bereite ich jetzt den Umstieg auf SU vor.

Was mich wundert is, daste die Leistung jetzt suchst, ohne auf die MS umgestellt zu haben ?

win

[head_guy6]

@headguy

Its not about Robert's Engine ... we are talking about mine ... I have a Newman cam which is supposed to be a good one.

My cylinder head is optimized based on what I have read in your book! My work can't be really bad because 220+NM is absolutely not bad for a dual carb engine!

so what can also cause that extreme dip of the torque curve after the engine reaches peak HP? I am sure you know that.

I can't think why people think Newman cams are so good.
This has always baffled me.
Newman cam designs haven't changed in 30+ yrs, and they were rubbish when I tested them back in 1983.
I've seen plenty of cams done by them recently which were dreadful, and more to the point were announced as "copies of works cams", but had no resemblance whatsoever. (eg. Hillmann imp steel repro).

The only Triumph one which worked approximately was the 300 degree version, (40-80) which worked OK in a short stroke motor.

As for your torque curve, the original CP TR5 camshaft has a torque curve which drops like a stone after 4000rpm.
With 20 degrees less duration, and dubious head flow, why do you think a newman cam should give you a better result?

As for the torque output of a the twin carb engine. we recently tested a 2.5L engine with one of my heads on and a TR5 (CP) cam. This engine gave a remarkable 175bhp. (in fact the owner was really astonished!).

The later long branch SU inlet manifold when flowed up correctly EASILY gives the same power output as 3 webers, especially when married up with a really nice exhaust manifold & gives better economy.

Flowing the inlet manifold is one of the secrets of getting good power out of the straight 6 engine, as branch 2 & 5 from the factory are 40% down on flow over the other branches.....

[darock]

As for your torque curve, the original CP TR5 camshaft has a torque curve which drops like a stone after 4000rpm.
With 20 degrees less duration, and dubious head flow, why do you think a newman cam should give you a better result?

As for the torque output of a the twin carb engine. we recently tested a 2.5L engine with one of my heads on and a TR5 (CP) cam. This engine gave a remarkable 175bhp. (in fact the owner was really astonished!).

so in your opinion the curve just looks like it should do.

IF the port flow in the head is the limiting factor, why does Jörg's engine peak 500rpm higher. Just because of the Weber carbs? I don't know if the head on his engine is optimized as well, i hope he will tell us.

@Win

Also die ZS magern bei mir oben raus nicht ab ... bei über 5000 umin habe ich 0.85 lambda. Was jedoch passiert ist, dass sich der Überdruck unter der Motorhaube extrem auswirkt. Wenn ich schneller fahre ... ab so 140 magert er ab. Man merkt auch wenn man ausgekuppelt mit 60 dahin rollt, dass der Leerlauf etwas erhöht ist. Könnte aber auch daran liegen, dass bei mir der Luftkanal vor dem Kühler noch fehlt.

Was du in deinem Fall probieren könntest wäre das Spritlevel in den Schwimmerkammern einwenig anzuheben ... Eventuell laufen deine Vergaser unter last langsam leer ...

Ich suche übrigens auch nicht nach Leistung. Ich will nur wissen ob da eventuell etwas nicht ganz richtig läuft. Die MS wird wahrscheinlich frühestens Ende der Saison fertig sein und bis dahin will ich einen Motor haben der perfekt läuft ;)

Bernhard

[head_guy6]

tut mir leid fur Englische sprache hier...

Here is an interesting graph for comparison:-



Notice several things.
The TR6 CP engine torque drops off a cliff after 4000rpm.
This is normal.
The valve lift is quite small, and perfectly matches the limited flow potential of the standard head.

Nota:- if there were to be a "characteristic" Triumph torque drop,it would be the kink at 3000rpm.
This is very hard to remove, as it's a function of exhaust resonance, inlet tract length, and the deficiencies of a 6 cylinder 2V engine.
There is little space in the engine bay to accomodate a LONGER inlet tract, which would tend to remove the typical "dead" spot between 3000-3800rpm. FYI, Jaguar didn't succeed here either on their 6 cylinder.

The 2L GT6 Pi although having a LOT less torque than the 2.5L has a much broader power band.
The peak torque at 5500rpm is still good at 192nm.
What is more important, the car has considerably FASTER acceleration to drive because of the much lower inertia of the 2L crankshaft.

It uses 38% less fuel to achieve this torque figure, -has very similar peak torque to the TR5 CP engine, but rockets past it from 4500rpm up.
It reaches 180bhp as an obviously very tractable road engine, which is a remarkable figure for a 2V per cylinder, 45 year old engine, quite apart from returning easily 8.5L/100kms, & easily passing a 87dBm noise test.
The engine has less than optimal CR, so could easily produce more torque.

Mr Nylen's engine from Sweden (Sweden TR club president) is very nice and produces good power.
Torque peaks considerably earlier than the GTT reference engine, but has a milder camshaft. This was a "no expense spared" motor.

FINALLY, (Emerald 3D) EFI 2.7L engine shows just how the "superiority" of EFI is what it is.

A myth.

If anything the power delivery is more peaky and less driveable, despite it having been set up by Dave Walker himself.
(it goes like crazy only between 4500rpm and an engine hammering 6000rpm)
That engine has probably the hottest cam here, but less than optimal head & exhaust.
The fuel consumption of this engine was noted, if anything as being WORSE than the Lucas injection reference engine.

Nota2:-
The "reference" engine used here had a STANDARD airbox and inlet barrel filter, as well as a STANDARD bottom end with hepolite 0.020" pistons, and STANDARD rockers.
The head was deliberately left at 10.4:1CR in order to run 95 Octane fuel.
Advance curve and fuel injection was modified from factory settings.

[darock]

The torque curve on the plot drops 20NM/500umin ... mine drops 40NM/500min ...

how about the ignition? where would you limit the advance on my engine to be save? 26°, 30°, 38° ?

currently it runs with the stock carb 38° and this, i think, is to much ... even with 98octane fuel ...

Bernhard

[head_guy6]

The torque curve on the plot drops 20NM/500umin ... mine drops 40NM/500min ...

how about the ignition? where would you limit the advance on my engine to be save? 26°, 30°, 38° ?

currently it runs with the stock carb 38° and this, i think, is to much ...

Bernhard

The reason you are running so much advance is because the real CR of your engine is dropping so fast.
You are not using fuel injection but a CD carburettor setup.
This presents a significant restriction to the engine, which drops the CR to as low as 7.5:1 as the revs rise.

CD carbs can only flow what the flow bench suggests....about 110cfm for a 1.5" carb and 145 for a 1.75 carb.
(eg. 2=290)

It is easy to see as engine revs rise, the amount of air (cfm) required rises exactly in proportion.
The STD head flows about 60-65cfm per inlet valve.

It is easy to see that 6 x this figure quite easily exceeds the flow capacity of the 2 carburettors and very possibly the inlet manifold, which in some cases I measured at as low as 40cfm on the robbed cylinders 2 & 5.

A moderately modified head flowing 80-82cfm at 0.360" valve lift would therefore tend to swamp 2 carburettors.

I made this experiment on a GT6 STD 2L engine, using 2 x 150CD Strombergs. On an unmodified inlet manifold, the engine "pinked" strongly, because 4 out of the 6 cylinders were getting high CR.

When the inlet manifold was modified and "equalised" for flow, the engine stopped pinking, and the carburettors clearly were TOO SMALL.
On our dyno tests, we were easily able to push the carb pistons to the top of their travel, resulting in the mixture going massively OVER-RICH.

In other words even the STANDARD GT6 2L engine is under carburetted, once the inlet manifold has been correctly modified, and needs 175CD Strombers or HS6 SU.
Now imagine what a 2.5L NEEDS!

[darock]

@ovi-wan

Das ist eine Leistungskurve wie ich mir das vorstelle. Abfallen ist ja klar, aber normal ist es nicht, dass es so rapide passiert wie auf meinem Ausdruck.

@headguy6

those are some really interesting numbers ... calculated conservatively with 80 cfm per inlet the ZS carbs are little bit more than HALF the size needed?

The air valves in my ZS reached top end pretty soon with stock springs so we put in yellow ones from SU which made them reach the top end at about 4500 rpm ... I don't have problems with over-rich mixture ...

Bernhard

[head_guy6]

headguy6

those are some really interesting numbers ... calculated conservatively with 80 cfm per inlet the ZS carbs are little bit more than HALF the size needed?

The air valves in my ZS reached top end pretty soon with stock springs so we put in yellow ones from SU which made them reach the top end at about 4500 rpm ..

As a rough guide a dual HS2 dual combo will struggle to exceed 85bhp.

a dual SU HS4/Stromberg 150 will max out at roughly 110bhp, irrespective of the 4 or 6cyl engine (austin mini, spitfire or GT6.)

As it's a matter of choke area, a SU HS6 or stromberg 175 pair will max out around 160bhp (eg. a really good blueprinted STAG 3L V8, or a really good well built TR6 2.5L engine).

These are well tried & tested numbers and are based on the engine torque peaking no higher than 4000rpm.

Anything above this is impossible as the carb will then present more and more of a constriction directly proportional to airflow, so as revs rise, compression ratio drops.

Kastner claimed to get 120bhp from 2 HS2 carbs on a 1300 engine.
As you can see, this is a complete fantasy.

No doubt such people are really regretting ever having claimed such stuff today,- AMERICAN horsepower rules indeed.

Btw I noticed this on another forum:-

Need Cam Advise 4 months ago:-

"Newman 260° cam plus Newman tappets ... You will love it!

I'm running that in my engine and love it.

Bernhard "

I wonder if this is still official in view of the results above?

[darock]

Now I am back to square one ...

You wrote a moderate ported head makes around 80cfm at 9.1mm lift
You also wrote a ZS 175 can do 145 cfm which makes 290 in total

I consider my head to be at least moderate ported and the cam makes 9.9mm lift. So again calculated with conservatively rated 70 cfm per inlet I get 420 cfm needed at maximum which is 45% more than what you say the dual ZS can handle ... Where is the failure in this thought?

Never ever would a dual ZS 175 setup make 160HP on a 2.5l TR6 engine ... Or has this ever been done? Maybe on a bigger engine or with a much wilder cam and far more expensive internals.

As far as the cam advice goes ... I am still happy with the Newman cam and would recommend it to anyone who asks.
It idles absolutely perfect and the torque is exactly what I expected (beside the drop of which I still don't know if its a cam feature or something else). Power output is even higher than I expected it to be with still a lot of potential on the ignition timing side.
Beside the fact that there are a lot less cam failures reported with Newman cams which you also wrote in an article I read on your jaguar page.

Also its not a discussion on how good this cam is ... I think schnippel has proven some really good results with it ... I still hope that he jumps into the discussion to show some plots and share some suggestions with us.

From my point of view, I still don't know what is going on in that engine and what is the restriction it faces after 4500 rpm ...

Wo sind die ganzen wissenden TR-Freun.de? Gibt hier ja mehr als 5 Leute die mehr als nur einwenig Erfahrung und Wissen haben.

Was mich aktuell immer noch brennend interessieren würde wäre ein dynochart und eine Zündkurve von einer am Prüfstand gemappten Trijekt ... soll ja doch mehrere geben die eine ähnliche Motorkonfiguration haben wie ich ... ich will sehen was das Optimum sein KANN ... Aber irgendwie scheint diese Information geheimer zu sein als der Bauplan der WC Anlage auf der ISS ...

Bernhard

[gelpont19]

Bernhard - die is öffentlich...

[roulli]

Hallo Bernhard

Welche Rollenkipphebel hast du? Welches Uebersetzungsverhaeltnis?
Stimmt die Geometrie?
Die von dir beschriebenen Symptome, Abfall der Leistung nach Umbau auf Rollen KH, koennen durchaus einer nicht angepassten Geometrie zu geordnet werden.
Die im Moss Katalog beschriebenen Massnahmen sind Minimalanforderungen und reichen nicht aus um die Geometrie von Rollen KH zu qualifizieren.
Die Unterseite der Rolle, die Mittelachse der KH Welle und die Kugel muessen auf einer Linie liegen.
Diese Linie muss bei halben Ventilhub senkrecht zum Ventilschaft stehen
Auf dieser Basis passt du die Hoehe der KH Welle Lagerboecke an.
Danach brauchst du Stoessel deren Laenge passt
Einfach KH durch Rollen KH ersetzen geht in den meisten Faellen nicht.

Gruss
Patrick

[darock]

Guter Einwand!

Das war aber schon vor dem Umbau auf Rollenkipphebel da. Der Prufstandsausdruck ist ja schon von November.

Über die Kipphebel selbst habe ich ein eigenes Thema verfasst.

werde mal beizeiten die Geometrie komtrollieren aber ich glaube nicht, dass das irgendetwas mit dem Verhalten hier zu tun hat.

Bernhard

[head_guy6]

Now I am back to square one ...

You wrote a ZS 175 can do 145 cfm which makes 290 in total

Never ever would a dual ZS 175 setup make 160HP on a 2.5l TR6 engine ... Or has this ever been done? Maybe on a bigger engine or with a much wilder cam and far more expensive internals.

As far as the cam advice goes ... I am still happy with the Newman cam and would recommend it to anyone who asks.
... torque is exactly what I expected (beside the drop of which I still don't know if its a cam feature or something else).

The torque is dropping right off, because the camshaft is a poor design, & this is absolutely normal, ie limited duration and lift
Even the STANDARD Limousine camshaft has more duration (270 deg).
The Triumph engines need camshafts with plenty of duration, which is exactly what they did to the Le Mans Spitfire engines when they tuned them up.

You wrote a moderate ported head makes around 80cfm

Actually it would have to be an EXCEPTIONALLY good head to do that. That is not MODERATE porting at all, it's top flight work which TBH I have never seen yet.

The best STD GT6 mk2 head I tested did 68cfm at 9mm lift.
This is more than a quick port job on a TR6 head does even on a good day.
That gives max 25bhp per cyl, which again is ALMOST EXACTLY what I got from a 2L Pi GT6 on a STD (270 degree) camshaft,but with a well modified head.

Btw for comparison:-
Mr Nigel G manages to get 160bhp from 2 SU carbs on a 2L engine (hotter cam+good flowed head). This is a very well known car in the UK & extremely well documented.

I just had a 2.5L tested earlier this month with a TR5 cam (not a hot cam) but with one of my heads and nothing special done to the bottom end (020" county pistons).

The head has a KNOWN flow figure because I tested it.

There were STANDARD rockers and the flow at 0.360" (9mm) is 77cfm on all ports.
FYI 77cfm/2.2 = theoretic Bhp.
I always use a 80% coefficient of this figure & this yields 28bhp per cylinder, which is ALMOST EXACTLY the power it made.

This engine registered as much as 176bhp** (I suggest probably 165, but the customer was really astonished).

FYI:-
The twin SU carb manifold fitted to the later 2.5S cars is VERY VERY good when modified.

No other manifold comes close, in fact it flows almost as well as a WEBER manifold, except the runners are longer, favouring good TORQUE.

Here are figures claimed before and after flow balancing on the "ordinary" SHORT Stromberg one from CW. (your type)



Port #1 Port #2 Port #3 Port #4 Port #5 Port #6
Before 88 57 86 85 57 88
After 91 87 90 91 87 91

Something of this doesn't make sense of course.

In order to test an inlet manifold you have to have a really good head bolted to it which outflows the manifold and set your maximum valve lift to something realistic.

I never measured figures anything like as high as this least of all from CW, who still believes the 219016 head is the ultimate Triumph head (which it is NOT).

I suspect the usual culprits haven't done this test properly at all.
They just bolted the manifold to a head without an inlet valve in, and tried to work out what happens next.
That is stupid.

I'll show the EXACT difference between the different inlet manifolds/heads in the next post.