Fiat 2 liter TC cam lift integral

[NOSferatu]

I have regrind cams of 304 (lift 10,6mm) degrees, and obviously with very mild lift integral.
The engine pulls strong from idle, and is easy to drive, but lacks torque on high rpm. Actually quite useless to rev over 6500 rpm.

The car is road car, but I want it to act like a real race car. It has cast pistons, so 7200rpm is a limit, but I would like it to rev more than now but still remain driveable, and what is most important, it must pass the exhaust pollution test.

Configuration:

Fiat 2.0TC
Regata or Ritmo 105 pistons
43,5 inlet valves fully flowbenchported head
10:1 CR (not very accurate, can be more, but not less)
Straight shot inlet manifold with 45mm throttlebodies, Hestec fuel injection/ignition.
4-1 tubular header

I have been offered cams of 290 degrees (lift 10,8mm), which are weldfilled before regrinding. Could those be better than my present cams?
What kind of cams would you recommend (degrees, lift ingegral, lift)?

[Guy Croft]

Nosferatu, hi!

See below, I have detailed the curves and lift integrals fro 3 cams, two of mine - either would work well but I'd not use the 3D with cast pistons. The 77 profile is what I'd call a mild StII and I'd not use anything with lower integral (shown in legend as inch x degrees) than the 77, because the torque is going to suffer. The 3A, for example, can deliver very good results, see the power/torque data in the reply I recently wrote in GC Q&A about sfc (specific fuel consumption) for NickRP.

The integral is readily summed from a cam map of lift by degrees which any good cam maker can map, although getting them to disclose their maps prior to purchase is not possible, for commercial reasons.

With comparisons made via integral measurement, it's important to know from what clearance it is measured, area under the curve below the set running clearance (shown on my graph) is meaningless of course because the cam is not in contact with the bucket. A cam maker could try to make their cam look more powerful than it is by not telling you this.

As far as welding up is concerned, I'm not a fan of this, there is enough stress on the lobe of a good competition cam without upsetting the metallurgy by heating it to weld temperature. I would certainly not take a claim for welding up a cast iron cam seriously, ever. Never mind the possible distortion of the cam axis..

GC

[Guy Croft]

By the way, what is Hestech fuel injection?

I am trying to start a whole series on different FI systems, under Gen Discussion, competition engines.

If you would like to write about it please pm me.

GC

[NOSferatu]

Hi, and thanks for quick answer!

Welding of cams is quite common in Finland, because of this:

http://en.wikipedia.org/wiki/Folkrace

Costs have to be kept as low as possible, and Fiat TC 1600 is the most used engine. VW aircooled was dominating before TC engines came popular.

BTW this engine is already driven 100000km, and I am already (slowly) gathering parts for my EVO2 engine, which probably utilizes 46/40 valves, forged pistons, steel lightweight conrods and dry sump lubrication.
For that engine I don't plan to do compromises with cams either, so your cams comes first, when deciding manufacturer.

Br, Sami

EDIT: Hestec is Finnish motor management system. It was quite state of the art system back in the 90's. For now some thinks it is has became little old, but it does what is is designed for.

http://www.sci.fi/~hestec2/english/index.htm

[Guy Croft]

Well, OK, I read your series link,

low cost cams might be fine if the objective of the race series is to keep costs low, but I would not do it with your motor. More than that I would not care to say!

I'll look up the injection system, thanks.

GC

[NOSferatu]

Hi again Guy!

Wonderful thing that guru like you share your knowledge with us amateurs and beginners!

I thought, that have you ever used Crane Cams (Cat Cams nowadays).

I have been surfing the website http://www.catcams.be/index.htm
but I don't understand their information tables enough to get a figure about lift integral.
Fiat TC billet cams are not widely sold in Finland, and Cat Cams is only available brand I know.
1900301 and 1900303 are available from shelf. What kind does those cams look in your eyes?

BTW, I have another unused regrinds in my shelf also. I know already, what is your opinion about regrinds :) , but what I should expect with these: (is it worth a try? I have already springs matched for this set)

Type: 19/312/C4 54/78-80/52 lift 11,4mm.
Inlet open at TDC 4,2mm exhaust 3,9mm.


Br, Sami

[Guy Croft]

Sorry, you need to know: I am not giving any advice on reprofiled 8v TC cams. I don't agree with the practice.

As for Cat Cams, you'll have to ask Cat.


GC