Is a more aggressive cam worth the cost?

[David Schmidt]

My 1990 3.6 Liter Carrera 2 is in the shop having the top end completely redone. It has nearly 100,000 miles and had developed engine oil leaks from all the cylinder heads...well you know the line.

The mechanic made a suggestion I hadn't anticipated when he asked me if I wanted to improve the performance of the engine. He said a more "aggressive" cam with 273 degrees (I think that's right) would give your car a moderate power boost in the 50 to 75 HP range, and would allow the engine to operate within "normal" parameters.

The good side of the suggestion is that he WON'T charge a labor cost to put them in because the engine is already apart! The downside is that they cost nearly $1,300 and I am a little nervous that the car will idle too wildly and sound a little strange compared to the stock cam. However, I know it's worth doing from a fun point-of-view based on the increase in HP!

Here are my questions:

1. Is it worth putting in the cams from a financial return perspective?

2. Will they make the car seem to sound or idle oddly after they've been in for a while. In other words...will I regret getting rid of the stock cams for the short-term thrill of the more aggressive cams?

3. Is there anything else to consider about installing these type of cams?

Thanks

[zippy_gg]

Question 4. Will the car still pass smog (especially if in California)?

[David Schmidt]

I'm located in Florida. We don't have auto emission testing anymore so this wouldn't be an issue!

[Tippy]

What is the purpose of the car? Track or street? If track, it'd probably make the car more fun. If putting around on the street is all you do with lots of stop and go, then I'd keep your cams now unless you just like the sound of big cams IMO.

Good news is, is your stock cams are highly sought after. Might be reason your mechanic wants you to upgrade.

[Steve@Rennsport]

Originally Posted by David Schmidt

My [B] He said a more "aggressive" cam with 273 degrees (I think that's right) would give your car a moderate power boost in the 50 to 75 HP range, and would allow the engine to operate within "normal" parameters.

OMG,..."50 to 75 HP range"??? If he said that, you need another (honest) mechanic.

The biggest cams you can use with the stock intake system would be the RS "supersport" cams and these must be made with 114 deg LC's to work properly.

Different software is also required for any camshaft modification as well.

I pray that your mechanic clarifies things for you so you don't have a big problem.

[David Schmidt]

Steve, thanks for your great technical points on the cam swap. I will dig deeper into this with the mechanic before making a decision.

If an owner were to install the RS "Supersport" cams as Steve mentioned, along with the software upgrade, what kind of horsepower increase could you expect to achieve from the $1,300 investment they cost?

And...if the C2 were to be used as an every day driver (which it will be), would you get tired of the louder sound and loopy idle that might be produced by the cams after a while?

Thanks

[Steve@Rennsport]

Originally Posted by David Schmidt;838809:confused: If an owner were to install the [B

RS "Supersport" cams[/B] as Steve mentioned, along with the software upgrade, what kind of horsepower increase could you expect to achieve from the $1,300 investment they cost?

Expect 7-12 BHP.

And...if the C2 were to be used as an every day driver (which it will be), would you get tired of the louder sound and loopy idle that might be produced by the cams after a while?

Sound is not affected (all that is from your choice of exhaust), however it will have a slightly lopey idle thats gone above 1200 RPM. Such choices are totally subjective so I would speak with people who have done this to get some reliable input.

[Bleedsblue]

Purely subjective, but I love the lopey sound in any car. It's one of the best parts of my M5 (stock). But for the cost/benefit ratio, I'd have a hard time justifying those cams by themselves. As mentioned, to really get gains you'd be spending way more on top of the cams.

I think there is a very good chance your mechanic is interested in your stock camshafts as Tippy guessed--not that that makes the mechanic a bad guy

[911SauCy]

Originally Posted by Steve@Rennsport

Expect 7-12 BHP.

I'm assuming these are wheel numbers but this is a real figure you see?

How incredibly disappointing...

Better off keeping the fuel tank half full and ditching the spare

[David Schmidt]

I appreciate all of your information and found it very useful in helping me reach a decision about the cam upgrade I was considering. It appears that the mechanic was over-selling the benefits of the cams based on the fact that he wouldn't charge a labor cost to install them because the engine was already apart.

As I am a daily driver who does a large amount of in-town driving...and not a lot of high-speed accelerating or highway driving, it makes sense to keep the stock cams.

I want to thank all of the people who regularly read and participate in the Pelican 911 Technical Forum, especially those who offer their kind assistance and expertise!

I just wanted to show-off the subject of our discussion:

[tratza]

When I had my 1987 3.2 rebuilt I had the cams reground by John Dougherty in California. Cost was a few hundred dollars and not $1300. HP gain was there but with some other changes (intake and exhaust) I couldn't tell how much gain from the cams. I did run it at two dyno shops which all came in at around 220 hp at the wheels or about 150 at the flywheel. I like the sound at idle and I can really feel them come on at about 3500 rpm.

[Bleedsblue]

Originally Posted by tratza

220 hp at the wheels or about 150 at the flywheel.

That's some SERIOUS reverse drivetrain loss

I know you meant 250 flywheel.

[Steve@Rennsport]

Originally Posted by 911SauCy

I'm assuming these are wheel numbers but this is a real figure you see?

How incredibly disappointing...

Better off keeping the fuel tank half full and ditching the spare

BHP is Brake Horsepower as measured by an engine brake, AKA Engine Dyno. This is what car manufactures use to measure and quote HP & Torque numbers. We use the same type of equipment.

Wheel HP numbers vary widely depending on the type & brand of chassis dyno so such figures can only be compared with themselves (on that day).

[clutch-monkey]

i found the 3.6 to be quite doughy and got the RS/cup cams put in, didn't feel much top end improvement but it really woke up the mid range.
especially paired with a lighter flywheel and a better exhaust.
quite worth it imo.

[JV911SYDNEY]

Originally Posted by David Schmidt

He said a more "aggressive" cam with 273 degrees (I think that's right) would give your car a moderate power boost in the 50 to 75 HP range

To say that's optimistic is putting it mildly.

$1300 or so for cams alone might not be "worth it" in bang for your buck terms but if you want them, get them. You only live once.

Further cams are just one aspect and should be considered as part of an upgrade package including but not limited to exhaust, chip, flywheel etc

[Bob Kontak]

Originally Posted by Steve@Rennsport

We use the same type of equipment.

Thank God for guys like Steve and Bruce Anderson.

[Shaun @ Tru6]

Originally Posted by Bob Kontak

Thank God for guys like Steve and Bruce Anderson.

+1, and John Walker, Matt Monson, Dave B... It's a nice list, we are very lucky to have such talent, expertise and experience here.

[brighton911]

When I read the HP claims I heard myself say "yeah right". Far inflated for sure. During the rebuild on my 3.2, I did go for DRC 964 cams and I'm pleased I did. (I should mention that the stock cams had some pitting so that had to be addressed). The end result was a noticeable difference in power throughout with the only downside being about a 10-15% drop in fuel mileage. Oh yes, and the cost to regrind my cams was less than 400.

[911SauCy]

Originally Posted by Steve@Rennsport

BHP is Brake Horsepower as measured by an engine brake, AKA Engine Dyno. This is what car manufactures use to measure and quote HP & Torque numbers. We use the same type of equipment.

Wheel HP numbers vary widely depending on the type & brand of chassis dyno so such figures can only be compared with themselves (on that day).

I was already very clear on the difference

I was really just stunned at the disappointing gain cams would provide.

Unfortunately, the more I learn about Porsche engine "upgrades", the cost associated, and the lack luster net gains...the more alright I am with leaving my 3.0 alone.

IMHO, boost seems like the only good "value" (dare I say that) of $ per hp.

Or maybe I'll just buy a C5 Z06 to get the "go fast" out of my system

[GH85Carrera]

Porsche was very good at getting most of the power reasonable out of the 911 engine. There are no simple upgrades unless you consider forced induction reasonable. Enjoy the reliability of a mostly unmodified 911 engine and accept the fact that big HP is not cost effective or reasonable.

With a small block Cheby the bolt on options are almost unlimited and cheap until you get into big HP.