Which engine to build?

[Jeff Alton]

What motor would you build out of a 3.2 if you had the choice, and why would you chose it? I am debating between a 3.2 with euro 10.3 pistons or a 3.4 with 9.5 or 9.8 pistons. I want to stay single plug if I can. Both motors would probably run 964 cams and use SSI's and custom SteveW chips. What would the power difference be between them? Thanks, Jeff

[asphaltgambler]

The biggest displacement that your budget and the OE fuel management will allow.

[efhughes3]

Jeff: I'm looking at the same decision. I believe I'm going 3.4 with close to 10:1 compression, and keep stock (chipped) DME.

I've been juggling between this and a 964 transplant, but like the idea of building a motor, and having it all new.

[350HP930]

Nothing beats the power of a turbo.

[Carrera3.5L]

Jeff, you know my answer! If you're willing to spend the money for high-compression 95's, spend a little more and get the 98's or 100's. You will be happier with the outcome. The advantage of 98's over 100's is that you can always stick the stock 95's back in if you ever want/need to. With 100's, you are committed.

You MAY be able to get away with single plug with 98's, but I wouldn't try it with 100's. While you have the heads off, have the machine work done (drill 2nd hole in heads and lower valve covers), you can always add the 964/993 distributor, Andial signal splitter and other ancillary stuff at a later date.

You may want to wait another week or two to decide as my 3.5L twin-plug Motronic motor will probably go on the dynojet late next week. We will also be running my buddie's 3.4L twin-plug Motronic motor at the same time. Both motors are virtually identical other then displacement and cam choice (964 for the 3.4L and 20/21 for mine). The compression ratio (9.5:1), induction (extrude honed plenums, overbored throttle body, etc), exhaust (1 5/8 headers with street muffler) and customized Steve Wong chip are identical in spec.

If his motor makes close, as much or more (perish the thought!) horsepower/torque, then obviously save the money and do 98's. If mine makes significantly more (cross your fingers) power/torque, then you may want to consider going with the 100's.

Will let you know the results when we do the deal.

Ralph

[Jeff Alton]

Ralph, I was wondering when you were going to respond!! I am not adverse to the 3.5 at all, infact there has been some really good deals on 100mm 10.5 piston and cylinders on ebay lately. What would you estimate the cost to twin plug, not including machining to be?? Splitter, wires and distributor. Did you look at a crank fired option at all??

I am very interested in the dyno runs. I think I will use the 3.8 sport cam from camgrinder instead of the 964 which I have in my 3.2. John thinks it would be a good match. It will be interesting to see just what the power difference is between the 3.4 and 3.5.

Thanks, Jeff

[Carrera3.5L]

Originally posted by catca
What would you estimate the cost to twin plug, not including machining to be?? Splitter, wires and distributor. Did you look at a crank fired option at all??

Hi Jeff,

It all depends on what you can get a good 964/993 distributor for. I picked mine up on ebay for $210 (sans caps & rotors) and proceeded to install a new drive belt, dust caps, caps, rotors and vent kit. Getting lucky and buying a good used unit should not cost you any more then $400 if you are patient. I think buying a complete rebuilt unit from Bosch with a 1 year warranty will cost in the $650-$700 range and buying new will be well over $1,000. All prices in USD of course!

Here is the short version:

Used Distributor $210
Caps, Rotors, Belt, Vent Kit, Dual Coils, Plugs $240
Andial Signal Splitter $525

You would need to fabricate a new coil bracket as well as decide on what wires you would want to run. Wire sets can be done a variety of ways. Figure anywhere from $250-$550 depending on what you choose.

RSR lower plug hold-down clips and nice wire separators add a little cost (about $100) but will help with the visual and "coolness" of the motor. Not absolutely needed though.

$290 for the machine work to drill the heads and lower valve covers.

Never considered crank-fire for the main reason that it would not pass the visual smog test here in California. The other main reason is that it doesn't look stock, which my motor does except for all of the bright red Magnecor wires running around.

Ralph

[asphaltgambler]

In the works for me. 3.4: 98mm P/C's -9:8-1 with wedge dome, Super-Cup grind, turbo oil pump with turbo piston squirters, extrude intake, larger t-body, B&B 3.6 street headers, not sure about muff yet, probably contact Steve W. about chip

I have 93 octane where I live.

[efhughes3]

AsphaltG: Are you planning the motor still or building?

Your list is very similar to what I've put together and got pricing together on last week.

[Jeff Alton]

Are you guys staying with single plug in your 3.4's. Also what piston and cylinders are you going to use?

Jeff

[efhughes3]

Jeff:

I'm going to go with JE pistons, and have my cylinders bored/replated. The guy I'm working with has assured me of no issues with the 98MM pistons, keeping under 10:1 and staying with single plug. We do have 93 octane here in TX.

[asphaltgambler]

efhughes3: Buying pieces / parts now. Custom JE's and single plug ignition. After many helpful answers here and through other experienced builders advice this combo is my choice.


I recently bought this car and the chain tensioner failed on a long trip with not-so-good results. I've already blown my budget somewhat with the purchase of the car. My mis-fortune.

Plus I cannot leave anything stock so as long as I was in there I would do it up, but simply. Just maximize the basic config with proiven parts combination.

[efhughes3]

Asphalt-I understand totally. "Breathed on" is the term I like. I've got a head stud issue (I think), and while I'm at it, a little improvement is in order.

[asphaltgambler]

You know, even though I was pissed-off about the tensioner deal, my mind went straight into the world of "As-long-as-I'm-inthere-what-ifs" I'm a hot rod guy 24-7. I just cannot seem to leave ANYTHING alone! From what I see this combo has a lot of potential.

Carrera3.5L has assembled a very nice combination and I am waiting with baited breath on the final HP/TQ numbers. His build was slightly more conservative camwise but more displacement. I think he is under Cali's extremely restrictive emissions programs' thumb + only 91 octane fuel.

[Jeff Alton]

Thanks for listing your setups. I am leaning towards twin plug and higher compression right now. I want all the power I can get and I also want something "trick" to show to clients!

Ralph, can you describe in words the power difference now that you have driven the car a little?!?

Thanks again, Jeff

[YTNUKLR]

Originally posted by asphaltgambler
conservative camwise...he is under Cali's extremely restrictive emissions programs' thumb + only 91 octane fuel.

Even though the camshafts aren't radical enough to suck the 330+ hp the 3.5 is easily capable of, they provide power EVERYWHERE, and lots of it. Low-end grunt is especially noticeable! Sweet engine.

[Carrera3.5L]

Originally posted by catca
Ralph, can you describe in words the power difference now that you have driven the car a little?!?

Thanks again, Jeff

Jeff, night and day difference. Those who read my long-winded rebuild threads know that my complaint with the 3.2L was the lack of low and mid-range torque. Nothing much happened below 3,500-4,000 even with Steve W's chip and some minor exhaust mods. The extra displacement makes a huge difference. Nail the throttle at 2,000 rpm in 2-5 and the motor pulls much, much harder all the way to the mid 6's. EXACTLY what I wanted and expected, it makes the car that much more enjoyable to drive.

But I also don't want to give the illusion that the car is blindingly fast. I wouldn't consider it scary fast, but maybe because it is a heavy Carrera and not something lighter. My car weighs about 2,800 lbs with a full tank of gas. I have no interest in lightening the car any more then I have done with removing the heat exchangers and heater blower assembly. The car is heavy mind you (for an impact bumper model), but the extra power this motor makes will at least help compensate some against some of the lighter, less powerful 911's. A mildly modified (i.e. bolt-on upgrades) SC or Carrera doesn't stand a chance, that I can tell you. My buddy Steve used to leave me in his wake with his 3.4L twin-plug motor. Now it should be a bit more even!

With the mild cam selection, the motor does seem to run out of breath at 6,500 or so, high rpm is not this motor's specialty nor was it the intent. The ARP rod bolts and AASCO valve springs were designed more as reliabilty upgrades then as performance upgrades. Even with a smooth G50, you just never know when you might miss a shift.

Yes, I am limited in what I could do horsepower wise due to MY PERSONAL constraints of being easily smog compliant (headers/heat exchangers swap in about 2 hours) and running on 91 octane. As it turned out, the octane really didn't matter much as I could only get to 9.5:1 CR anyway.

As far I'm concerned, mission accomplished. The motor is light years better then it was before in my opinion and should run strong for well over 100,000 miles.

Rapidly approaching 1,000 miles and did a 320 mile 2-day round trip to San Diego last week. Only used half a tank of gas at 80-85 mph. Motor is bone dry underneath and I swear has not used a drop of oil thus far. The dipstick measurement has barely moved. I guess I did a good job of seating the rings, eh?

Even in smog trim, a larger motor is nice to drive. The three of you guys (and any others lurking) are going to have some fun with your builds.

Ralph

P.S. - Once again, sorry for being long-winded.

[Carrera3.5L]

Originally posted by YTNUKLR
Even though the camshafts aren't radical enough to suck the 330+ hp the 3.5 is easily capable of, they provide power EVERYWHERE, and lots of it. Low-end grunt is especially noticeable! Sweet engine.

Yeah, Scott can tell you first hand with an unbiased view. He is the only one so far (other then my wife) who has ridden in the car for any great distance. With him, I never took the motor over 5,000 as it only had a couple of hundred miles on it at the time.

Ralph

[efhughes3]

Man, I wanted to get the February DE uinder my belt before starting in. I might not wait that long. I'm getting pumped about taking the plunge!!

Ralph: My wife and I are coming out just prior to Christmas, we're staying at a new(?) Marriott in Newport/Corona del Mar. If it's convenient, I'd love to perhaps meet up with you and see your baby. We get in sometine on the 22nd, and fly out Christmas afternoon.

[Carrera3.5L]

Originally posted by efhughes3
Man, I wanted to get the February DE uinder my belt before starting in. I might not wait that long. I'm getting pumped about taking the plunge!!

Ralph: My wife and I are coming out just prior to Christmas, we're staying at a new(?) Marriott in Newport/Corona del Mar. If it's convenient, I'd love to perhaps meet up with you and see your baby. We get in sometine on the 22nd, and fly out Christmas afternoon.

Ed,

No problem. I'll PM you my info. We're about 20-30 minutes away so not a big deal. The in-laws will be in town for Christmas so a perfect reason to get away for a bit.

I gotta find a way to get up and see Jeff as well, as he is only about 10-15 minutes from my parents house. He keeps drinking my beer!

Ralph