Performance Cams

[Targa Florio]

Dear Alfisti,

I have a 1750 engined step nose 105.

I have bought a set of performance cams from IAP.

I have been told by a local Alfa guru that I really should fit high compression pistons to obtain any noticeable benefit from the cams.

All I want is for a little more power from my road only
1750.

I am not interested in time trialling it (or sprinting it on a track as is done in Australia).

May I please have some advice.

Best Regards

Targa Florio

Adelaide Australia

1966 Giulia sprint GT Veloce

[74veloce]

You could go with up to a 10.5:1 compression and get a pretty substantial performance boost, but you would want to put in oversize valves as well. I'm not sure who makes higher compression pistons for these motors, J&E perhaps? You could probably get them through Paul Spruell Motorsports.
You'll probably see the difference with just the cams and as they are the easiest part to replace, you may want to stick them in and see how you like it before tearing down the engine.

[davbert]

just put them in and dont monkey with new pistons...

i had IAP 11mm cams in my 2.0 L alfette gtv 20yrs ago and they work nicely with the stock pistons.

if i recall correctly the 1750 has a half point more CR than the 2000 to boot.


of course you would benefit with upping the CR but is it worth the $$$ ? then again our green backs arent worth much these days...

perhaps money is better spent on flowing and decking the head for a .5 CR increase than swapping out pistons?

for what its worth.

db

[AR67202]

pistons would allow you to rev the engine higher, without destroying your engine, provided they are lighter than stock.... and if going to performance cams, you just might need to rev it a bit higher...

[davbert]

stock con rods are good for 7000, with the 11mm IAP cams peak power happens way before that, so why put in pistons for the higher revs? please remember he'd mention his 1750 is for road use only and dosent intend to use it on the track.

sure the gains with cams arent huge.... but what other single component for that price that gives you those gains?

im guessing about 10-15hp with cams alone and its definately noticable if you dont commute daily in a C4 vette. I dont think 10:5 pistons will give you that by itself.

please remember he'd mention he's 1750 is for road use only and dosent intend to use it on the track.

[ToonRboy]

Hi Targa Florio,

Which cams did you purchase? You know, you probably should have spoke to your Alfa Guru before buying them, yes?

What kind of driving do you do and when (in the RPM range) would you want your power to come in? Working with less than 2L is a bit of a challenge you know. The factory has probably already done what you're looking for!

Without displacement, it's virtually impossible to get any more ummf, down low without power adders (NOS/SC/Turbo). Cam's will get you a tad more power, but up top. Combine the perf cams with more compression (10.5:1 or better) and you can attain substantial more (percentage-wise), but down low will suffer a lot.

I don't know the 1750, but maybe you can have the head decked for a lot less than forged pistons, and that should buy you a teeny bit of compression and leverage the benefit of the cams a bit more. I'd make sure my fuel system is running tip-top...

[Norm]

I think higher compression benefits the entire RPM range. Cams tend to offer a more limited range of benefit.

What RPM the change occers, seems to depend on the valve timing, at least in my experiance. Personally I like 99.5 or 102 for autocross or daily driving. I can set it up for higher RPM if i'm expecting a track event.

w/ the intake cam around 99.5 or 97 you can even get rid of the wet (flat) spot between idle and 2000 rpm.
Probably not great for ultimate HP but damn fun for driving around town.
(the ability to adjust valve timing events to suit is the single coolest thing about these motors)

My understanding is the loss of "low end" is in the switch to large dia headers.
And, like most people you want more power, without the loss of drivability.

Cams are where most people start. don't forget that with the higher lift cams you'll need new springs.

Caveats
I'm blessed and limited by the spica FI to cams w/ relativly less duration than a carby cam. I'm guessing that a carbed car might behave somewhat differently