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post #1 of 18 (permalink) Old 06-18-2019, 02:31 PM Thread Starter
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2600 power curves

Not wanting to hijack PS70s - thread "2000T new project " thread any further ,I thought I would start a separate thread on engine power . with no knowledge but hopefully those that do know will add something and answer BORA1978 questions.

Firstly I have to congratulate BORA1978 on getting a 2600 engine up to 7500 rpm and backdown again in one piece - my understanding is it has a resonant frequency around 6800 and can self destruct if you hold it there for too long . 6500 is enough for me .

These are the power curves i have .

Blue is std 2600 spider on Solexes
Green is my car with high lift cams and triple dellortos DLH40
Red is a race engine with triple 45 Webers - Max power just under 200 BHP at 5500 rpm why bother going higher just makes more noise or a big bang

On the tuned cars with webers or dellortos you get a race car with a big power dip in the mid range - can anyone offer any advice to fix this.?
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post #2 of 18 (permalink) Old 06-18-2019, 02:47 PM Thread Starter
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Jet cover venting

so moving on to my next question - weber jet cover venting

This seems to have become a possible route to removing weber flat spots

As below PS70 has posted pictures ( picture 1) of a design developed to add air directly into he jets - weber did actually do this on certain applications (picture 2 ) but this is rumoured to be to allow additional air at high rpm/

I run dellortos that already have a vented jet cover ( Item 25 pick 3 )but mysteriously the gasket underneath Item 28 is solid and blocks any air flow. This is only opened up on turbo applications .

I think I will try removing the gasket to see if this improved the light flat spot I currently have .
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post #3 of 18 (permalink) Old 06-18-2019, 02:54 PM Thread Starter
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Or just 4 cylinders

And finally I have a 1750 GT race car with identical high lift cams and twin DHLA 40s . This has been set up by a professional carb tuner . Produces 140BHP at 6,000 rpm with strong power and torque torque across all engine speeds. So 210 BHP must be possible from a 2600 correctly tuned?
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post #4 of 18 (permalink) Old 06-18-2019, 04:57 PM
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Ian,

The dreaded flat spot has so many theories behind it that I'm starting to think J. Edgar Hoover is alive and involved.

Do you have the mixture plot for the dyno runs you've listed above?

I'm starting to play with a new-concept replacement for the emulsion tube produced by a fellow name Keith Franck. I installed them today, and have a sense they've made a difference. https://www.webstore.com/82598,owner_id,other_items

First, my car has the OKP bespoke manifold. I believe a desiamesed manifold is still going to be a compromise as compared to a correct, straight-shot Weber manifold. Turbulence can do nasty things.

Keith's work appears to be addressing the richness that often occurs during WOT in the middle RPM range. I'm including the last dyno run I did on my 2300, and you'll note that, although the torque curve is fairly flat, the mixture goes off-the-scale-rich during transition. Presumably, this can be fixed by juggling alternative E-tubes, mains, and air correctors. Before I did that, I tried Keith's "VF" tubes. I think it's working based upon the Mk1 Rumpometer.

I don't know what he does for Dellortos, but maybe he has something for them as well. I'd try a set before hanging plumbing all over creation.

I think it's meaningful that the Cast Iron 2000's have always been fussy to convert to Webers, even when de-siamesed. With my OKP manifold (and the essentially identical FNM manifold), it was very nearly plug and play. In all cases, I've plumbed the float bowl vents straight into the air plenum, sucking on the same air adjacent to the carb air intakes.

The red traces are with FNM manfold, 40DCOMs, and stock cams. The Blue curves are OKP mani, 45DCOE9s, and improved Webcam cams. (Idle's great at 700 RPM)

On the red runs, we shut down at 6,000 RPM, as indicated on the dyno screen. I was handling the throttle on the blue runs, and shut down when the tach said 6,000, revealing about a 10% difference between a calibrated dyno, and Italian tachometers. I plan to revisit the dyno at some point this summer, and compare the VFs, etc, plus go to the same 6,000 calibrated revs.
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Don P
Carson City, NV

Past Alfas...
59 102 Touring (first Alfa $500 running)
65 Sprint GT (2nd Alfa, $500 daily driver)
102 Sprint (never did anything with it, but wish I had)
74 Berlina (first new car - now certainly rusted into oblivion)
61 Giulietta Spider G-Prod Race Car (where is it now?)
84 Spider Veloce (rarely drove it, so sold it)
86 Quadrifoglio (Dull car - no more 115s for me)
1971 Montreal "The Full Monty". Fair winds and following seas

Current Alfas
59 102 Touring Roadster - restoration complete, enough Alfa for any rational man. Or irrational, for that matter
Oops. Add to the "present" list, 10204 01488, 2000 Touring Roadster project

And past...
Two 1946 Stampe SV4C (c/n 294 "Rocinante" - wife's favorite airplane. RIP), and c/n 235 "La Bon Temps Femme" (gone to a new home, but never forgotten)
Zlin 50LA (+9 -6 gees, titanium spar, 1200 lbs, 260HP rumored to now be in Brazil)
1946 Luscombe 8A
Starduster Too (recently spotted at the Nevada City, CA airport - over 20 years and an entire continent separating it from our stewardship in Binghamton, NY)
1955 Cessna 170B (wife taught me to fly tailwheel in this)

And present...
64 Mooney M20E ("Rambo". My faithful steed for over 40 years) Over 55 years old, and just returned from a trip to Argentina in him
Newest in the fleet
1967 Piper Super Cub on Wipline amphibious floats (a true "all terrain vehicle")
2010 Triumph Thunderbird


You can snap roll an Alfa only one time...

Last edited by DPeterson3; 06-18-2019 at 05:03 PM.
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post #5 of 18 (permalink) Old 06-19-2019, 09:48 AM
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Keith does have the VF tubes for Dellortos. My 63 Giulia abnormale has Dellortos and I installed a set. My Rumpometer also sensed improvement. More of a PIA to install than on webers as the float covers have to come off.

Neil
1958 Touring Spider in restoration
1963 Giulia Spider "slightly" abnormale
1967 Giulia Sprint GT (aka Stepnose) with 3.0 V6 and a/c
Now full time in Magalia CA.
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post #6 of 18 (permalink) Old 06-19-2019, 09:56 AM
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Neil,

When are you going to open the hood on your 10204 showing the world your solution for the “log-dragging” CI 2000?

Don P
Carson City, NV

Past Alfas...
59 102 Touring (first Alfa $500 running)
65 Sprint GT (2nd Alfa, $500 daily driver)
102 Sprint (never did anything with it, but wish I had)
74 Berlina (first new car - now certainly rusted into oblivion)
61 Giulietta Spider G-Prod Race Car (where is it now?)
84 Spider Veloce (rarely drove it, so sold it)
86 Quadrifoglio (Dull car - no more 115s for me)
1971 Montreal "The Full Monty". Fair winds and following seas

Current Alfas
59 102 Touring Roadster - restoration complete, enough Alfa for any rational man. Or irrational, for that matter
Oops. Add to the "present" list, 10204 01488, 2000 Touring Roadster project

And past...
Two 1946 Stampe SV4C (c/n 294 "Rocinante" - wife's favorite airplane. RIP), and c/n 235 "La Bon Temps Femme" (gone to a new home, but never forgotten)
Zlin 50LA (+9 -6 gees, titanium spar, 1200 lbs, 260HP rumored to now be in Brazil)
1946 Luscombe 8A
Starduster Too (recently spotted at the Nevada City, CA airport - over 20 years and an entire continent separating it from our stewardship in Binghamton, NY)
1955 Cessna 170B (wife taught me to fly tailwheel in this)

And present...
64 Mooney M20E ("Rambo". My faithful steed for over 40 years) Over 55 years old, and just returned from a trip to Argentina in him
Newest in the fleet
1967 Piper Super Cub on Wipline amphibious floats (a true "all terrain vehicle")
2010 Triumph Thunderbird


You can snap roll an Alfa only one time...
DPeterson3 is online now  
post #7 of 18 (permalink) Old 06-19-2019, 10:37 AM
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When its done which will be soon. It is now logo'ed with alfa romeo script.

Neil
1958 Touring Spider in restoration
1963 Giulia Spider "slightly" abnormale
1967 Giulia Sprint GT (aka Stepnose) with 3.0 V6 and a/c
Now full time in Magalia CA.
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post #8 of 18 (permalink) Old 06-19-2019, 01:41 PM Thread Starter
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Weber Manifold

Don, My 2600 is fitted with an original Weber manifold so that is one tick in the box. Still looking for the rolling road air figures
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post #9 of 18 (permalink) Old 06-19-2019, 07:31 PM
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To carry on...

There is a veeerrryyyy long thread by Keith Franck and his followers. His research continues, and he’s got the tools to do quick prototyping.

Many of his ideas either make no sense, or make no sense to me. Let’s go with the latter for now. Regardless of his theories, his work is specifically focused on the mid-range, WOT power slump. There’s too many testimonials to throw rocks at it. My own test in the last few days would confirm at least some improvement.

I hope someone battling a de-Siamesed manifold tries his VF tubes and reports in.

Don P
Carson City, NV

Past Alfas...
59 102 Touring (first Alfa $500 running)
65 Sprint GT (2nd Alfa, $500 daily driver)
102 Sprint (never did anything with it, but wish I had)
74 Berlina (first new car - now certainly rusted into oblivion)
61 Giulietta Spider G-Prod Race Car (where is it now?)
84 Spider Veloce (rarely drove it, so sold it)
86 Quadrifoglio (Dull car - no more 115s for me)
1971 Montreal "The Full Monty". Fair winds and following seas

Current Alfas
59 102 Touring Roadster - restoration complete, enough Alfa for any rational man. Or irrational, for that matter
Oops. Add to the "present" list, 10204 01488, 2000 Touring Roadster project

And past...
Two 1946 Stampe SV4C (c/n 294 "Rocinante" - wife's favorite airplane. RIP), and c/n 235 "La Bon Temps Femme" (gone to a new home, but never forgotten)
Zlin 50LA (+9 -6 gees, titanium spar, 1200 lbs, 260HP rumored to now be in Brazil)
1946 Luscombe 8A
Starduster Too (recently spotted at the Nevada City, CA airport - over 20 years and an entire continent separating it from our stewardship in Binghamton, NY)
1955 Cessna 170B (wife taught me to fly tailwheel in this)

And present...
64 Mooney M20E ("Rambo". My faithful steed for over 40 years) Over 55 years old, and just returned from a trip to Argentina in him
Newest in the fleet
1967 Piper Super Cub on Wipline amphibious floats (a true "all terrain vehicle")
2010 Triumph Thunderbird


You can snap roll an Alfa only one time...
DPeterson3 is online now  
post #10 of 18 (permalink) Old 06-20-2019, 12:00 AM
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As the torque band contours of my racing 2600 coupe are shown in Red Merlins original post, perhaps I should add something here.

The 'flat spot the size of Lincolnshire' was a constant frustration. Toward the end of many efforts to eliminate it, I concluded that it might well be an induction length/wave flow issue.

I believe that 210 bhp is achievable, but you have to be careful of the 6-cyl destructive harmonic vibration period.

I understand that the subsequent owner/racer of my 2600 coupe, Tony Murray, made some progress but I do not know how or where.
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post #11 of 18 (permalink) Old 06-20-2019, 01:58 AM Thread Starter
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Inbalance over 6000 rpm

There is a general acceptance that straight 6 engines have an imbalance in the third order harmonics.

This was all part of my University degree many years ago , all now forgotten. I had a lecturer who specilised in consultancy on vibration reduction , his general recommendation was to fill the offending item with concrete!

The best I can find on the in line 6 is

"The inline six has both first and second order harmonics in balance. There is a minor imbalance in a third-order frequency that can only be detected with sophisticated instrumentation"

I still however would never take my 2600 engine above 6,000 rpm as you have already got the power , its not a zippy bike engine. The last ( and only) 2600 engine I rebuilt had been destroyed by its previous owner. His car was not roadworthy so he used to sit in the garage reving the engine up to 8,000 rpm marvelling at what a wonderfull engine it was and loving the roar of the tripple Webers.

Then it seized

No 6 main bearing had spun and welded itself to the crankshaft. This happens if all the oilways are not carefully cleaned out during a rebuild as any swarf and other rubbish tends to block oil feed from the crank to No6 . I am sure periods of reving to 8,000 without proper engine cooling would have shown any lack of oil feed.

What worries me is he has now bought the engine I rebuilt back and is planning to do the same!

This is his last email - there is no hope for him

"I was taking into account you rebuilding the engine, which is why I didn’t
offer too much money. ( thanks!) I will probably run the engine in at somewhere like
“Nordschleife” making certain there is a flatbed to get me home nearby. (Usual “running in” method, Adrian Ratcliff used 9,000 rpm, I had my engine nearer 8,000 rpm down in the Forest of Dean
)"

- YEP this engine he has already seized once and I rebuilt it - I give up.

.
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post #12 of 18 (permalink) Old 06-20-2019, 02:07 AM Thread Starter
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Adrian Ratcliffe

Adrian Ratcliffe referred to is no longer with us but was an accomplished racer and motor racing commentator.

Photo attached of "Miss Piggy " his 2600 Sprint. Obviously not the greatest reference for preserving your 2600 engine!

Quote from the Vintage Racing Club of BC


“His driving style was spectacular! On the original 165 x 400 mm Michelins he campaigned for many years, usually sideways … I recall at the 1979 Portland Historics the organizers called him in for a “discussion”, never having seen anyone drive in such uninhibited style! “Corner? What corner?” he would say, the car sideways with smoke pouring off all four tires.”

Adrian Ratcliffe demonstrates how to take Turn 2 (Clubhouse Corner) at Westwood in his Alfa 2600 while racing with the late Ray Clarke in the Cobra circa 1981. - photo courtesy David Birchall

Adrian raced that Alfa Romeo, nicknamed ‘Piggy’ for many years. David again:


In 1985 Adrian rolled ‘Piggy’ during a race at Westwood. He was lucky to survive. With no roll bar and only a lap belt when the driver’s door came open as the car rolled, he was thrown from the car during the roll and was lucky not to be crushed – I kid you not. He was sucked back in by the grace of… ‘Piggy’ was not so lucky and never ran again.

Long time racer and VRCBC member Leigh Anderson remembers that incident very well:


Adrian’s superb controlled slides in that Alfa were pure magic. The day he rolled the Alfa at the Westwood hairpin is still a vivid memory for me as he rolled it because his brakes failed, and he was about to rear-end me at a very high rate of speed as I braked for the hairpin in my little sports racer. I probably would not be here talking about it today had he not risked his own life
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post #13 of 18 (permalink) Old 06-20-2019, 09:20 AM
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The thought of racing a 102/106 on 165X400s boggles. One might assume the wild drifts were intentional. I suspect he simply developed a means to avoid losing things entirely, and get it all back on track before the next curve. My understanding is that Piggy was actually a 102 chassis, not a 106, so wonder if it still had the front drums rather than later 2600 disks? While they're impressive drum brakes, I'd never want to race them.

Don P
Carson City, NV

Past Alfas...
59 102 Touring (first Alfa $500 running)
65 Sprint GT (2nd Alfa, $500 daily driver)
102 Sprint (never did anything with it, but wish I had)
74 Berlina (first new car - now certainly rusted into oblivion)
61 Giulietta Spider G-Prod Race Car (where is it now?)
84 Spider Veloce (rarely drove it, so sold it)
86 Quadrifoglio (Dull car - no more 115s for me)
1971 Montreal "The Full Monty". Fair winds and following seas

Current Alfas
59 102 Touring Roadster - restoration complete, enough Alfa for any rational man. Or irrational, for that matter
Oops. Add to the "present" list, 10204 01488, 2000 Touring Roadster project

And past...
Two 1946 Stampe SV4C (c/n 294 "Rocinante" - wife's favorite airplane. RIP), and c/n 235 "La Bon Temps Femme" (gone to a new home, but never forgotten)
Zlin 50LA (+9 -6 gees, titanium spar, 1200 lbs, 260HP rumored to now be in Brazil)
1946 Luscombe 8A
Starduster Too (recently spotted at the Nevada City, CA airport - over 20 years and an entire continent separating it from our stewardship in Binghamton, NY)
1955 Cessna 170B (wife taught me to fly tailwheel in this)

And present...
64 Mooney M20E ("Rambo". My faithful steed for over 40 years) Over 55 years old, and just returned from a trip to Argentina in him
Newest in the fleet
1967 Piper Super Cub on Wipline amphibious floats (a true "all terrain vehicle")
2010 Triumph Thunderbird


You can snap roll an Alfa only one time...
DPeterson3 is online now  
post #14 of 18 (permalink) Old 06-20-2019, 11:24 AM
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Hi everybody,

Hi Don,

Quote:
Originally Posted by DPeterson3 View Post
I hope someone battling a de-Siamesed manifold tries his VF tubes and reports in.
I could ! : What are the reference you purchase for your 2300 RIO ?

How did you manage to measure the air/fuel ratio during the power and torque measurement ?
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post #15 of 18 (permalink) Old 06-20-2019, 11:37 AM
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Quote:
Originally Posted by DPeterson3 View Post
The thought of racing a 102/106 on 165X400s boggles. One might assume the wild drifts were intentional. I suspect he simply developed a means to avoid losing things entirely, and get it all back on track before the next curve. My understanding is that Piggy was actually a 102 chassis, not a 106, so wonder if it still had the front drums rather than later 2600 disks? While they're impressive drum brakes, I'd never want to race them.
Piggy was a converted 102 Sprint with a 106 engine and 106 front suspension and front disk brakes (but drums on rear axle). The rear axle had a welded-up differential (i.e. 100% non-slip), so tire grip while cornering must have been poor -- but that also helped with drifting and/or power sliding.

-Ruedi
[SIZE="1"]'63 2600 Touring Spider (AR 191437, the car that started the 2000/2600 International Register, reassembly in progress)
ex-'65 2600 SZ (AR 856043, the car in my avatar, sold as resto project to Austria)
Maintainer of a private 2600 SZ register (not the one in the Netherlands).[/SIZE]
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