Recommend a cam for a 3.2

AlfonsoR · 05-09-2011, 10:45 PM

Been doing some research on cams but can not find anything definitive. From some posts, I like what I hear about DC cams, plus camgrinder seems to be a straight shooter, so was thinking of a DC 19 or 20? Ideally, I would like rev range to about 7500, and peak hp at about 7000.

The engine is basically stock, including induction. I was planning on upgrading to ARP rod bolts on stock rods and probably to a 930 oil pump.

What else will I need to upgrade? What is the max revs for the stock rods? Will I need upgraded springs and retainers? Forged rockers too? I don't want to go to the point of cross drilling the crank though.

I would really appreciate any input from folks who have either of the cams.

Thanks in advance.

AlfonsoR · 05-10-2011, 06:57 AM

A few more details on my car... It's an 89 with 100k miles on the clock. Original pistons and cylinders. The car has had a recent head job done by PO at 98,000 miles.

I'm opening the engine to reseal since I have a one or two bad oil leaks. I will be changing out bearings and reinspecting Ps&Cs. Basically a mild engine refresh, at least that's what I think I'm getting into. No telling what will happen when I actually open the thing. The "while you're in there" list can tend to get long as I understand.

Steve@Rennsport · 05-10-2011, 09:08 AM

Quote:

Originally Posted by AlfonsoR

Been doing some research on cams but can not find anything definitive. From some posts, I like what I hear about DC cams, plus camgrinder seems to be a straight shooter, so was thinking of a DC 19 or 20? Ideally, I would like rev range to about 7500, and peak hp at about 7000.

The engine is basically stock, including induction. I was planning on upgrading to ARP rod bolts on stock rods and probably to a 930 oil pump.

What else will I need to upgrade? What is the max revs for the stock rods? Will I need upgraded springs and retainers? Forged rockers too? I don't want to go to the point of cross drilling the crank though.

I would really appreciate any input from folks who have either of the cams.

Thanks in advance.

I cannot tell you what cams you should use, but I can tell you that your stock induction system and a compatible cam profile will not permit usable power to 7K, much less 7500 RPM.

Further, those RPM levels require better rods, bearings and some oiling modifications to the bottom end of the engine for reliability.

Engines are comprised of matched assemblies where every aspect is designed to work together.

If you intend to retain the OEM intake system, my only suggestion would be to scale back your camshaft and RPM requirements to a realistic level unless you are willing to change that to either carburetors or an ITB system with Engine Management.

AlfonsoR · 05-10-2011, 08:15 PM

Hey Steve, thanks for the reply!

I thought the stock rods and induction system had a little more in them in terms of RPM, but I'll take your word for it. So would you recommend going with a cam with higher lift? What all will I need to upgrade?

Thanks again.

Steve@Rennsport · 05-10-2011, 11:41 PM

Quote:

Originally Posted by AlfonsoR

Hey Steve, thanks for the reply!

I thought the stock rods and induction system had a little more in them in terms of RPM, but I'll take your word for it. So would you recommend going with a cam with higher lift? What all will I need to upgrade?

Thanks again.

One chooses a cam based on several factors and some of them include:

1) How will the car be used? street, street & DE events, racing?

2) Induction system characteristics.

3) Stock gears? (one doesn't want to narrow the engine's torque range when using stock ratios).

4) Exhaust system.

5) Engine displacement.

Depending on the operating range of the cam you choose, you may need to upgrade the rod bolts, valve springs and valve spring retainers; all for reliability.

See?,.....and you thought this would be easy,...

OldTee · 05-11-2011, 03:20 AM

I put a 964 grind cam in a 87 Carrera which seems to work well. Contact Camgrinder for suggestions. Not as flexilble down low, more ommph further up. Gas milage about the same.

AlfonsoR · 05-11-2011, 06:57 AM

Steve,

I understand what you're getting at. When modifying a car you should look at the big picture and modify the system as a whole and not be singularly focused on one component or one aspect.

I would love to do all things it takes to get the "GT3 like" experience out of my air cooled car... But I'm not so sure this is the platform i want to invest heavily in, at least not at this point. So for now, I want to keep upgrades at a minimum and do mods that don't change the original look.

AlfonsoR · 05-11-2011, 07:03 AM

Old Tee, thanks for the suggestion. Do you use the car as a daily driver? On a quick run, did you change your shift point any, 964 cam vs 3.2cam?

Steve@Rennsport · 05-11-2011, 07:56 AM

Quote:

Originally Posted by AlfonsoR

Steve,

I understand what you're getting at. When modifying a car you should look at the big picture and modify the system as a whole and not be singularly focused on one component or one aspect.

Exactly!!!!

Quote:

I would love to do all things it takes to get the "GT3 like" experience out of my air cooled car... But I'm not so sure this is the platform i want to invest heavily in, at least not at this point. So for now, I want to keep upgrades at a minimum and do mods that don't change the original look.

As you know, GT-3 motors are very advanced, high RPM engines and while its quite possible to replicate that experience with an air-cooled one, its decidedly not cheap to do.

This would require different induction, cams, pistons, and exhaust system. Not smog compliant, either.

I always ask my clients two questions:

1) What do you want the car to perform like?

2) What is the budget to accomplish this?

The answers really frame whats going to be possible to do.

Remember, good results are always preceeded by good planning and clear objectives. It sounds like you might need to work on this aspect a little bit.

OldTee · 05-11-2011, 01:26 PM

Quote:

Originally Posted by AlfonsoR

Old Tee, thanks for the suggestion. Do you use the car as a daily driver? On a quick run, did you change your shift point any, 964 cam vs 3.2cam?

Daily driver.

camgrinder · 05-12-2011, 09:06 AM

What compression ratio do you have? 9.5-1 works well with the 964 profile.
Higher compression (10.3-1) you can run a little more camshaft,
Can a 964 super Sport Camshaft be used with CIS and/or Motronic?

AlfonsoR · 05-12-2011, 11:01 PM

Hey John, thanks for chiming in. I have stock US engine which I believe is 9.5:1 c.r. I guess Mike (richemj) from your refferenced link has a similar setup to what you're recommending?

What else do I need to upgrade? Can my cams be used for a regrind or is it better to go new?

Thanks.

camgrinder · 05-13-2011, 09:30 AM

Quote:

Originally Posted by AlfonsoR

Hey John, thanks for chiming in. I have stock US engine which I believe is 9.5:1 c.r. I guess Mike (richemj) from your refferenced link has a similar setup to what you're recommending?

What else do I need to upgrade? Can my cams be used for a regrind or is it better to go new?

Thanks.

Regrind the 3.2 cams to 964 specs. No need for new cams. The 993SS or DC21 can be ground on 3.2 cams, but I prefer to make them on billets. Rockers should be rebuilt or replaced, and rocker shafts inspected and polished.

I don't remember what compression ratio Mike is running with the DC21 cams. The DC21 is similar to the 993SS, with a little more exhaust duration.

AlfonsoR · 05-13-2011, 11:08 AM

Thanks John. Once I open it up and know what I have, I will give you a call.

Alfonso

kinein · kinein's Garage

so what happen i have a 3.2 i want to do similiar upgrades info plz

AlfonsoR · 05-19-2011, 09:19 AM

I have another project to finish before I work on my 911.

If you want info, contact John Dougherty of Dougherty Racing Cams. Dougherty Racing Cams

hcoles · 05-20-2011, 05:47 AM

964 regrind from John works very well, rev limiter stock, IMO don't try to make the motor into something it is not, as mentioned above big changes require coordination of other changes. You might feel the idle slightly less smooth, but this is probably on a case by case basis, you can pass smog easily in CA, I've heard ;-) When on the track you might also run a test pipe, this seems to add a bit at the higher end.

kinein · kinein's Garage

for the money is the power you getn from it worth it?

hcoles · 05-20-2011, 06:39 AM

I know a number of 3.2 cars with CGrinder 964 cams. All are happy with the cam change, in terms of performance gain and $/performance gain. If you are in there anyway, changing the cams is not much additional effort or cost. With the stock cam the engine seems to nose over just when you are wanting some torque, this seems to be eliminated to a big extent with the 964 and test pipe. The car is fine with the stock cams as well. It's not going to be a high power car in any case.