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(Post Link) post #1 of 10 Old 16-09-11 Thread Starter
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Comparison of Modifications to the 3.2

There are a few graphs I have on my PC that I'd like to post for some discussion. They refer to three basic types of modification: NA 3.8 conversion, centrifugal superchaged 3.2, and the "Selcuk" modified intake/ throttle body (I hope Selcuk won't mind, but since he has done such interesting work in this regard, I thought it appropriate).

The graphs speak for themselves, and while of course, other variables such as exhaust modifications will apply in the case of some graphs, there is clearly a surprising similarity in the gains achieved in each case. If you look at the power figures at 3000, 4000, 5000, 6000, in each case, you'll see what I mean.

Comments, corrections, recriminations and abuse, all welcomed.
Attached Images
File Type: jpg selcuk_plenum.jpg (40.1 KB, 82 views)
File Type: jpg GTA 3.7 dyno.jpg (60.2 KB, 81 views)
File Type: jpg ALFA_GT-Supercharged.jpg (37.2 KB, 74 views)

Last edited by stooge166; 16-09-11 at 10:53.
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Originally Posted by stooge166 View Post
Comments, corrections, recriminations and abuse, all welcomed.
Do I see well that N/A 3,7 conversion was dynoed around 270 bhp and carbon plenum on 3,2 gives 285 BHP???? Also 260-270Nm maximum torque on 3,7? something is wrong there....
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Three completely different dynos... that is what is wrong...

If you want to compare 3 cars, do it on the same dyno, or dont do it at all. It is pointless because you could easily have 5+% difference going from one to other dyno.
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Yes Tribesman, easily 5% difference in dynos, but I don't think 5% covers the "wrong" that Gotcha is concerned about. Both the 3.8 and the supercharger are very costly upgrades; high four figures at least. The plenum and throttle body is comparatively cheap. I have looked at a lot of dynographs posted for these modifications, well the 3.8 and supercharger at least, and I don't believe these are unrepresentative graphs.

Sure, a few percent out for different dynos, but basically, that's the shape and scale of the power curves delivered. I don't believe one should expect much more from the 3.8 and the SC; it's more that I'm a bit shocked at the improvement from the plenum (the throttlebody is probably a very small part of this gain).
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Any links to these Tb's etc you are talking about man? And get yourself to the Alfa meet next weeekend.
 
(Post Link) post #6 of 10 Old 17-09-11 Thread Starter
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Originally Posted by Damien_C View Post
Any links to these Tb's etc you are talking about man? And get yourself to the Alfa meet next weeekend.
It's the plenum that's of most interest Damien. Search under Selcuk and you should find it easy enough.

I will get to one of the meets one of these days. I'd love to catch an Octane C&C as well, but all my free time these days is taken up looking after the young fellas while their mother is studying. In a few months when the youngest is a bit bigger I'll bring them along.
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so we should look at fitting such a plenum to a 3.7/8 and dynoing that...
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Quote:
Originally Posted by gotcha View Post
Do I see well that N/A 3,7 conversion was dynoed around 270 bhp and carbon plenum on 3,2 gives 285 BHP???? Also 260-270Nm maximum torque on 3,7? something is wrong there....
I think the 3.7 dyno graph is MattyB's one done a year or 2 ago, if so, then IIRC the 270bhp was ATW rather than calculated at the flywheel. I may be wrong though, Stooge, can you confirm?




*Edit - If it is the same graph, they calculated 287bhp from 270ATW in the thread... https://www.alfaowner.com/Forum/alfa-...o-results.html
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(Post Link) post #9 of 10 Old 19-09-11 Thread Starter
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Originally Posted by Cuore_Sportivo_155 View Post
so we should look at fitting such a plenum to a 3.7/8 and dynoing that...
I very much look forward to seeing that, if you can post it up somewhere. I'd hope it would allow the bigger engine to do itself justice, at least up to 6000 or 6250 or so.

Yes, Bacon, the lower graph seems to indicate slightly higher power, maybe the main graph was taken at the wheel axles, which I think costs around 8% efficiency.
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Can't really let the figures talk for themselves as they are pretty hard to make out! Are the figures at the wheels or flywheel? I think the 3.2 GT is at the wheels but I couldn't really see what the others were from the documents. Might be easier if you could just post the summary numbers for each type. Or post bigger images....

Cheers,

Nigel
 
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