Couple questions about a 3.2 rebuild

Rich76_911s · Rich76_911s's Garage

Hey guys I have a couple questions. I am working on getting my engine sent to Steve at rennsport, hopefully this week it goes out. Anyway I had a couple questions that I want to ask.

1. One of my cams has some pitting on it. So it is going to have to get fixed. Can cams be ground to the 964 style and still have no issues with valve to piston clearance with the original pistons? I did a search and saw one post that said it was OK with motronic pistons but I want to be certain.

2. What does the regrind to 964 cams do to the engine performance wise? I've heard people like it, but how does it change the characteristics of the engine?

3. I am at pretty high altitude typically the car will be running between 6 and 10 thousand feet. Should I take this into consideration if I am going to regrind the cams?

4. MAF, is this mass air flow, and can anything be done to improve the engine's performance from here?

5. Bored throttle bodies. I guess first I should ask what is a throttle body. I think I know but honestly I am not sure so I want to check and make sure I have it right. What does boring out the throttle body do? Who does this work and roughly how much does it cost?

I am looking for a couple small upgrades. I can't afford new Pistons and cylinders at this time, and SSI's are going to have to wait until the budget is a bit larger too. But since I have the engine apart I thought a couple of these might be reasonable. Thanks for all and any help you can share. I appreciate it a lot.

Rich

asphaltgambler · 12-14-2005, 05:28 PM

Rich the answers you seek have been covered many times previous. Try the 'search" button with each topic. If you still have questions check back / update.

ChrisBennet · ChrisBennet's Garage

Steve seems happy to share his wisdom even if you aren't a customer but if he will be doing your motor you shouldn't feel guilty about asking him these questions. He loves to talk Porsches and he'll steer you right.
-Chris

camgrinder · 12-14-2005, 07:58 PM

Question 1, Yes the 964 cams clear the 3.2 pistons, but you should always measure your valve to piston clearance.

Question 2, Normally the increase is from 2500 to 6500 rpms. 3.2 engines respond nicely to the 964 cam upgrade.

Question 3, The reduced atmospheric pressure at high elevations will have a dramatic effect on power. I would bump the compression ratio as high (10-1) as I could and run a cam like my DC13 profile. THe DC13 has similar valve lift figures to a 964 profile, but less overall duration. I originally designed it for lower compression ratio 3.0 litres, but it would work nicely in your combination.

Carrera3.5L · Carrera3.5L's Garage

I wouldn't bother boring the throttle body unless planning on extrude honing or porting/polishing the manifolds or changing to the 964 plastic units.

Supposing you do modify the plenums, and if Steve can't or doesn't want to bother boring the throttle body, I can have it done for you for $180 if you send the throttle body. My buddy Steve Becker owns a machine shop and has done them for a few local motors (mine included), as well as for a few Pelicans I've sent to him.

He can safely enlarge it about 3mm. Here's a pic:

Don't worry, Steve Becker's not a hack. Here is a testament to his credentials. Read the second paragraph:

http://www.porsche.com/usa/eventsandracing/motorsport/sales/sales-porsche962/porsche962-history/

I agree with Chris, if Steve's building your motor, you don't need to ask our opinion.

Ralph

cjr1 · 12-18-2005, 09:13 AM

Rich,
I just finished my rebuild on a 85 3.2 with 964 cams.Pretty much all stock except for the cams internally.Does run out very well with noticable kick above 2500-2700 rpm up to about redline.Have not pushed real hard yet due to weather,but does feel like a nice low $$ upgrade.EBS reground my stock cams while doing my heads.Very happy!

Good Luck & Have Fun!

Chris

Rich76_911s · Rich76_911s's Garage

Thanks for all your imput everyone. I appreciate the help, and appologize for asking questions that had been covered previously. I did search but I guess I missed the posts that had the information that I was looking for. Camgrinder I appreciate your input. I wish I could bump up the compression but I do not think that will fit into my budget right now. If my P's and C's are shot I will then consider it, but if they are fine I am going to have to settle with the originals. There is no other way to increase compression other than with new p's and c's is there? ? ?