Cam comparison: Pittatore 87&201 and Fiat orig - Measured

Competition engines and ancillaries - general discussion
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emil
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Cam comparison: Pittatore 87&201 and Fiat orig - Measured

Post by emil »

Hello Guy and others,
I have been looking to buy a set of high lift/large lift integral cams for the 1800cc TC engine I'm planning to build.

I currently have a Pittatore type 87 inlet cam and a 1608 exh cam on the 2L engine I have been running for the last 5 yrs. I was offered a set of Alquati/Pittatore type 201 (also referred to as A25/2) but since I couldn't find much data on them (see my thread viewtopic.php?f=4&t=1748&p=9157#p9157) I decided to measure them myself.
I also have a number of different original Fiat camshafts and decided to measure them as well while I was at it. I was very surprised to find that the 1608, '79 US 2L 131 and 2L 132/Argenta all had IDENTICAL lift profiles. Especially since the 1608-profile is considered by many to be one of the strongest original profiles and the US 2L 131-engine has the worst specific power in modern time. Just goes to show the importance of cam timing I guess.

In the following attachments you will find a graphs showing all measured profiles, as well as graphs showing the two Pittatore profiles and the three original profiles (zoomed to show the minimal difference).
I found the 201 profile to be quite 'strong' in my opinion. Especially the ramps differ in a significant way when comparing to the 87 or original profiles. Does any other forum member (or Guy) have any comments? I am also interested in getting opinions re. valve clearance when running the 201 profile. It seems to me that I should run with very little clearance on this profile (maybe as little as 0,25-0,3mm?) since the ramp is so short. Any comments on this, please?

To compare the different profile's lift integral I made a very crude sort of "Riemann" integral calculation. I believe the calculation is fairly valid since the profiles are symmetric and the errors should cancel out. However, I measured with varying interval so I wouldn't trust the values entirely. See them as guide-lines..
Anyway, I'll attach a graph showing the integral values.
Please note that the integrals are calculated with zero valve clearance, which obviously is incorrect. Also note that all graphs have CAD (Crank Angle Degrees) on the x-axis and mm on the y-axis. Thus the integrals are in [CAD*mm]. If you prefer cam degrees, inches or both they can easily be changed in the spreadsheat.
Just for the sake of comparison the 77 profile's integral is approx. 24% larger than the original and the 201 profile is 39% larger.

When measuring I used a calibrated Mitutoyo digital DTI, and had the cams placed in a cam-housing with the probe placed on a cam bucket. I measured with varying interval length; 2 - 5 cam degrees.

Hope these measurements can come in handy. Now I just hope my 130TC head will have enough high valve lift flow capacity to make full use of the cams.

Regards,
Emil
Attachments
valvelift_all.JPG
valvelift_all.JPG (71.52 KiB) Viewed 7820 times
valvelift_pittatore.JPG
valvelift_pittatore.JPG (58.96 KiB) Viewed 7821 times
valvelift_FIAT.JPG
valvelift_FIAT.JPG (31.79 KiB) Viewed 7819 times
integral.JPG
integral.JPG (24.77 KiB) Viewed 7819 times
'74 Fiat 124 Spider
Guy Croft
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Re: Cam comparison: Pittatore 87&201 and Fiat orig - Measured

Post by Guy Croft »

An interesting post, well done.

I just want to remark that I will not allow actual Excel spreadsheets of aftermarket cams to be published - first the respected Italian firm Pittatore are still very much in existence and secondly it could be my cams next. Gif and Jpeg maps no problem.

GC
emil
Posts: 14
Joined: August 21st, 2006, 8:44 am
Location: Uppsala, Sweden
Contact:

Re: Cam comparison: Pittatore 87&201 and Fiat orig - Measured

Post by emil »

Hi,
Sorry about that Guy. I won't attach spreadsheet data again.
Do you Guy (or anyone else) have any comments when it comes to the relatively steep ramps? I realize it is common practice to design the ramps this way in order to increase lift integral, but in what way does affect the need for reduced valve clearance (if at all)?
Thanks again for your invaluable help!!
Best regards,
Emil
'74 Fiat 124 Spider
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