964 vs DC35 cam

[mepstein]

How much of a difference are there between these cams? I was planning on using a set of 964 cams on my 3.2 to 3.4 build but a buddy gave me a set of new DC35 cams that he didn’t need. Max Moritz style pistons. Thoughts, opinions, criticism? Thanks.

[Peter M]

What induction are you planning to use?

[Trackrash]

Apparently there are two versions of DC 35s. One will most likely make the valves hit those pistons.

You can contact John Dougherty, aka camgrinder, and ask, he will know. As mentioned you need to consider what intake you will be running.

http://www.drcamshafts.com/911profiles.htm

[mepstein]

Stock 3.2 intake at first. Will add Sal's MAF system later.
They were purchased for a fairly stock 3.2 so I'm sure they are the EFI version.

[Peter M]

You may have to rethink your timing with regard your MAF upgrade.

I installed John's 993SS cams in my 3.4 upgrade - a bit milder than DC35 cams - and it was all but undrivable with the standard 3.2 AFM and ECU setup.

I also suspect you will have piston to valve clearance problems with the DC35's as well unless you flycut the pistons.

Irrespective of what cams you use, I suggest you need to upgrade the ecu at the same time as your mechanical works

[mepstein]

I have a custom SW chip for the 964 cams. Sal's MAF comes with new injectors and ecu and a custom chip. I will check the valve clearance during the build. I can always go to the 964 cams but was wondering if I could use the DC35 with good results.

[Helix8]

Originally Posted by mepstein

I have a custom SW chip for the 964 cams. Sal's MAF comes with new injectors and ecu and a custom chip. I will check the valve clearance during the build. I can always go to the 964 cams but was wondering if I could use the DC35 with good results.

I would ask Sal about the DC35 specs (may be an issue) - he helped me with my cam choice during a 3.4L build

[mepstein]

Originally Posted by Helix8

I would ask Sal about the DC35 specs (may be an issue) - he helped me with my cam choice during a 3.4L build

Good point. I will.

[Neil Harvey]

Originally Posted by mepstein

Good point. I will.

We recently built a 3.4L engine for a customer and ran into this exactly issue. It still does not sit well with me on how we moved forward.

As a performance engine supplier it was counter objective to build and engine based upon the "tuners" ability to tune. In this particular project, the customer has purchased some intake parts along with a "eprom" tune from a tuner. We had a cam profile decided to achieve or exceed the customers performance goals. This is our job as an engjne supplier.

We were told by the "tuner" that the cam we had chosen would not work and the tuner would not be able to tune the engine to suit. Idle was one concern, which I remember stating, this is a race engine, who cares if it idles higher than stock?

I called and discussed this issue with Steve Wong, who told me he has had and would have no issues tuning the engine with the cam we wanted to used. Unfortunately we had to use a cam the tuner wanted in this case, which did not sit well with me and still to this day does not. We used a safe street cam that is all about meeting emissions not performance.

Tune to the engine, not the other way. If the tuner cannot tune the engine with the parts you wish to use, use another tuner. We do not build many engine that require eprom re mapping, but I recommend Steve Wong for any of this work as he has no issues tuning to the engine.

[mepstein]

Originally Posted by Neil Harvey

We recently built a 3.4L engine for a customer and ran into this exactly issue. It still does not sit well with me on how we moved forward.

As a performance engine supplier it was counter objective to build and engine based upon the "tuners" ability to tune. In this particular project, the customer has purchased some intake parts along with a "eprom" tune from a tuner. We had a cam profile decided to achieve or exceed the customers performance goals. This is our job as an engjne supplier.

We were told by the "tuner" that the cam we had chosen would not work and the tuner would not be able to tune the engine to suit. Idle was one concern, which I remember stating, this is a race engine, who cares if it idles higher than stock?

I called and discussed this issue with Steve Wong, who told me he has had and would have no issues tuning the engine with the cam we wanted to used. Unfortunately we had to use a cam the tuner wanted in this case, which did not sit well with me and still to this day does not. We used a safe street cam that is all about meeting emissions not performance.

Tune to the engine, not the other way. If the tuner cannot tune the engine with the parts you wish to use, use another tuner. We do not build many engine that require eprom re mapping, but I recommend Steve Wong for any of this work as he has no issues tuning to the engine.

Neil - I’d be happy to one day know 1% of what you know about engines. I’m just putting this question out there because I don’t know if the difference between the two cams is a major point, more of a wash that won’t make a difference or something in between. Right now the engine is a stock running motor with about 150k. I’m prepping it to go into a 914 but except for new fuel lines, backdate heat and 914-6 heat exchangers, I’m not changing it just yet. I have new 3.4 Mahle cylinders, J&E MM style pistons and the DC35 cams but I’m in no hurry to tear down a running engine. I’m just curious to whether I should stick with what I have or look to other options. I know you’ve mentioned making some updated parts so that’s certainly a consideration as well. Thanks, mark

[Nux]

The DC35 will not clear your max Moritz pistons.

993SS or DC20 is as far as you can go, but even with these you may have to change the timing to accomodate the clearance.

I would go with 964 and sell the DC35 - or modify/change pistons. But as Neil mentioned - choose the cam for the engine, not the engine for the cam.

[Peter M]

Originally Posted by Neil Harvey

We recently built a 3.4L engine for a customer and ran into this exactly issue. It still does not sit well with me on how we moved forward.

As a performance engine supplier it was counter objective to build and engine based upon the "tuners" ability to tune. In this particular project, the customer has purchased some intake parts along with a "eprom" tune from a tuner. We had a cam profile decided to achieve or exceed the customers performance goals. This is our job as an engjne supplier.

We were told by the "tuner" that the cam we had chosen would not work and the tuner would not be able to tune the engine to suit. Idle was one concern, which I remember stating, this is a race engine, who cares if it idles higher than stock?

I called and discussed this issue with Steve Wong, who told me he has had and would have no issues tuning the engine with the cam we wanted to used. Unfortunately we had to use a cam the tuner wanted in this case, which did not sit well with me and still to this day does not. We used a safe street cam that is all about meeting emissions not performance.

Tune to the engine, not the other way. If the tuner cannot tune the engine with the parts you wish to use, use another tuner. We do not build many engine that require eprom re mapping, but I recommend Steve Wong for any of this work as he has no issues tuning to the engine.

Neil,
What cam did you want to use?

I'm assuming you were using the standard 3.2 inlet manifold?

For a street driven 3.4 with standard 3.2 inlet manifold, 10.3:1 compression ratio, modern fully tuneable efi, twin plug and headers, what cam would you recommend?

Thanks
Peter

[Iciclehead]

I am putting DC35's into my 3.4 build, but it will have ITB's, the Mahle 10.3/98MM P/C's which have a dome piston top and valve pockets, Motec and Eisenmann exhaust.

The DC 35 was a recommendation by Dougherty for a cam that would give a good balance of performance, torque at midrange, fuel economy and general driveability and civility for what in essence will be a 911 tourer.

I trust Dougherty based on his reputation on this forum...so sure hoping he is right in my case!

Dennis

[Neil Harvey]

Originally Posted by Peter M

Neil,
What cam did you want to use?

I'm assuming you were using the standard 3.2 inlet manifold?

For a street driven 3.4 with standard 3.2 inlet manifold, 10.3:1 compression ratio, modern fully tuneable efi, twin plug and headers, what cam would you recommend?

Thanks
Peter

We used a stock 964 profile with LC's at 113°. This was the only camshaft the tuner could tune. For the engines use, the wrong cam choice.

Our customer had already purchased this tuners MAF kit and tune, so we had no choice but to go along with whatever would give our customer the best result. Sad, but sometimes you have to go along with what you have in front of you. As much as it goes against my grain!!!

We had designed a new profile for this engine, but just before we sent the file off to the cam company, we found out that this tuner could not tune the engine with our choice.

This needs to be a learning situation to anyone thinking of building any engine. Build it on paper first, completely, so you know every step and understand all compromises.

When choosing a cam shaft profile, the choice needs to be done before you decide upon the piston to use. There is no point in choosing a cam that will not fit. Decide upon the engines use, where you need the torque, emissions etc., and build from there. The piston can be made to suit, with the desired CR and enough pocket depth to run the cam you choose along with its position in the engine's rotation.

Part of that choice needs to include any tuning required. If it will include eprom mapping then choose the tuner who has the best control over the mapping.

This was a learning experience for me as well. I was very disappointed for my customer, as we could not give him the engine we knew could. All because of a 1/3 parties inability to do what was required.

Never again!!!!!

[Peter M]

Originally Posted by Neil Harvey

….Part of that choice needs to include any tuning required. If it will include eprom mapping then choose the tuner who has the best control over the mapping.

Neil,
Why do you think people spend tens of thousands on their engine build but persist with trying to remap their old Motronic to suit?

Surely using a modern easily tuneable speed density or even a MAF set up with the standard 3.2 inlet manifold opens up the cam choice to be as wide as what you could use with carbs or ITB's?

I'm particularly interested in your thoughts on cam selection for a street engine with a single throttle body.

TIA!

[Neil Harvey]

My last post that stated, "never again", was probably too strong a comment without some sort of explanation.

I was very disappointed for our customer that his end result was compromised by the tuners inability to tune the engine we wanted to supply. We do not get involved in re mapping these older eprom engines. We rely upon those that know what they are doing. My last time reprogramming an eprom was during my Porsche racing days in the late 80's.

The "never again" was a comment based upon the we have now a better solution for these 3.4L upgrades single plug engines.

A new piston, new Rod, the cam profile we wanted to use originally and after a long discussion with Steve Wong, a known tuner that has no limitations to tuning any engine that uses the older style Motronic system.

We did come off the original cam profile that would clear the wedged piston, but this was still a no go for the tuner the customer had selected. As an engine supplier, we do not need to be limited by the tuners inability to tune an engine.

This is not to say the engine we supplied was not a good result, but it could have been better.

[Neil Harvey]

Originally Posted by Peter M

Neil,
Why do you think people spend tens of thousands on their engine build but persist with trying to remap their old Motronic to suit?

Surely using a modern easily tuneable speed density or even a MAF set up with the standard 3.2 inlet manifold opens up the cam choice to be as wide as what you could use with carbs or ITB's?

I'm particularly interested in your thoughts on cam selection for a street engine with a single throttle body.

TIA!

Often the budget limits the choice of an aftermarket EFI system.

You are correct, a modern EFI system opens up the final engine config. EFI is just a tool that allows you control of the engines running. The only difference is the amount of control and many added features. Most EFI systems todays are streets ahead of any eprom based system, but a poorly programmed modern system is no where as good as a well programmed eprom. Again, with many other parts of an engine, it comes down to the humans in charge.

As for a cam for street use, I'm not too familiar with "street use". This can be one thing to one and another to someone else. A better way is to figure out the performance you want and where in the rev range you want that performance. Street or track use.

[K24madness]

To the OP, why limit your choices to 964 or DC35? In your shoes I’d sell em both and buy the cams that are properly suited to your application. I really like the DC21’s! Talk to John about best LSA to get the proper valve events for your build.

Neil I cringe hearing that story! I may not have handled it as diplomatically as you did. It’s crazy to spec an engine around ECU/Tuner limitations on a race car. That mindset comes from street engines that need to retain stock ECU’s for OBD2 and SMOG. I will somewhat disagree on budget being the primary driver of stock ECU’s though. I think most owners can’t comprehend/quantify the value so it’s easy to defer back to stock. The latest offerings by Motec, AEM, Megasquirt, Lifesracing and VIPeC are a dream come true for me. The GUI’s have become so user friendly that tuning changes are a breeze. Many of em can ride the knock sensors like a modern factory ECU and have fast wideband closed loop control. These are the good old days in my opinion!

[mepstein]

The reason I asked about the cam choices is because I'm working off a recipe that a couple people have successfully used to build their 3.2/3.4 engines. I don't have the experience of years of engine building or the knowledge of many different products so I'm left to "borrow" the build from people who are willing to share what has worked for them. I'm not trying to build the ultimate Carrera engine. I am budget limited. If a modern efi system is way better for my build, I'll use it but if the stock motronic will do the job and not require many hours of dyno time to tune properly, well then stock it is. So while I know the 964 cam set was working well for the "recipe" that I was given, I was curious to know if the DC35 cams were similar in form and function.

When it's mentioned to get rid of both sets of cams but buy DC21's because -I really like them, it really doesn't give me much to go on. Why are the DC21's properly suited to my application?

[Trackrash]

John Dougherty has the answer. Do you have a number from the cams?

I see two different DC 35s listed on Dougherty's web site.

Here is your plan: Decide on your compression, displacement, pistons, intake and exhaust and call John. He will know.