3.2 spark?

sundevil64 · sundevil64's Garage

I am considering some options for my longhood hot rod project. My options are 3.3 turbo motor with SC cams or 3.2 with either EFI or PMO's.

I would have to buy the pmo's. I have all the rest.

IF, I were to go to PMO's (Carbs-46mm) where are you pulling spark from? Are you changing distributors? Custom dizzy's? Crank sensors?

I am trying to get a full range vision of this project. It will determine to flare or not to flare (engine choice).

Thanks,

John

Roger 911 · Roger 911's Garage

For clarification, are you saying you have a choice of using either a 3.3 turbo long block, or a 3.2 long block, where you intend to install either EFI or PMOs on whichever you choose?

Roger

rusnak · 08-05-2013, 08:54 AM

Unless you want to make your longhood into a 1980s looking turbo, go with the non-turbo.

And unless you need a custom cam, go with the Motronic setup. You'll have a super bulletproof system, notwithstanding a shaky DME relay, but overall you'll save many hours and many $$ going with the stock L-Jetronic or variant.

Roger 911 · Roger 911's Garage

...assuming we're talking about long blocks here, a 3.3 turbo motor has extremely low compression pistons (like 7:1) to compensate for the boosted intake charge. I can't see that making for a good normally aspirated motor. Vs 9.5:1 (US) on the 3.2.

FYI - I think the white 911 on last month's Excellence cover uses PMOs with the stock Motronic to manage the ignition. (Edit: For future reference. I reread the article on this car and this is not correct. My bad.)

Roger

sundevil64 · sundevil64's Garage

Quote:

Originally Posted by Roger 911

For clarification, are you saying you have a choice of using either a 3.3 turbo long block, or a 3.2 long block, where you intend to install either EFI or PMOs on whichever you choose?

Roger

I have a choice of motors. Either a 79 930 3.3 Turbo motor complete with EFI, EDIS, and 993 heat exchangers with twin wastegate and K27 HFS OR a complete 3.2 coming out of a donor 85 carrera OR use the same 3.2 longblock and put PMO carbs on it to keep it simple and look just a little period correct.

Roger 911 · Roger 911's Garage

OK. That' how I read it at first. Boy, it sure would be tempting to go for the complete turbo motor. I prefer "go" over "show".

Roger

sundevil64 · sundevil64's Garage

Quote:

Originally Posted by rusnak

Unless you want to make your longhood into a 1980s looking turbo, go with the non-turbo.

And unless you need a custom cam, go with the Motronic setup. You'll have a super bulletproof system, notwithstanding a shaky DME relay, but overall you'll save many hours and many $$ going with the stock L-Jetronic or variant.

Oh gosh no. I wouldn't make a longhood look like a later car for nothing. I was thinking about putting custom cams with the PMO's. You are correct on the cost side. I have an 85 carrera that I got running and driving this weekend that I am going to use for a donor for this longhood (nicknamed "Blu"). Obviously the cheapest route would be to move everything over and run it that way.

Quote:

Originally Posted by Roger 911

...assuming we're talking about long blocks here, a 3.3 turbo motor has extremely low compression pistons (like 7:1) to compensate for the boosted intake charge. I can't see that making for a good normally aspirated motor. Vs 9.5:1 (US) on the 3.2.

FYI - I think the white 911 on last month's Excellence cover uses PMOs with the stock Motronic to manage the ignition.

Roger

Roger, If I were to move the 3.3 over it would be as a full turbo motor. I have concerns about drivetrain longevity there.

sundevil64 · sundevil64's Garage

Roger,

Yes that turbo motor would really "go" in that light car, but there are some obstacles that need to be over come also. I may be able to hide an IC under a duck tail. I know the stock will fit, but I have a full bay that would not fit and I would have to fab or have a custom one made. It's so hot here in TX that it is a significant factor. Although there is a knock sensor that will retard timing should the first signs show. The only problem is a knock sensor only tells you what has already happened and sometimes that is too late.

Roger 911 · Roger 911's Garage

The turbo option would certainly require a plethora of related changes (e.g., what tranny would you be using with that?).

I just completed the stock 3.2 swap into my 72. It was really straightforward. However, I will confess that the engine bay looked a lot better with a Weber carbed 2.4 in it, versus a Motronic 3.2. Oh well, I can't see that from behind the wheel!

sundevil64 · sundevil64's Garage

Roger,

I saw your thread. It was so timely. Nice job by the way. I like the look of the earlier cars' engine bay. I could go itb's for about the same cost of PMO's, but then it's not as simple. I have also just acquired a euro car that is absent a motor, but has the Euro dme in it. The timing curves will help waken up the 3.2.

Thankfully I have options.

I was going to run a beefed up 915 with LSD, 84 side plate that is thicker, and stronger gears. Still I would have to shift with finesse. This is where I am worried.

If I run the 3.2 I would run the 901 as it is a better shifting trans than the 915 and looks correct in the car.

What I need to do is find another early car and put the turbo in with a 4 speed and call it a day and run the 3.2 in the hot rod.

rusnak · 08-05-2013, 11:40 AM

Roger, you might comment on the power and torque difference of the 3.2 w Motronic vs the 2.4 with carbs.

To me, there is no contest.

sundevil64 · sundevil64's Garage

I wonder how much better the power is with 964 cams or even SS cams?
I will want to do head work to this 3.2 either way. It has about 140k on it. Not sure of the history. I'm a regular on the slippery slopes.

Roger 911 · Roger 911's Garage

Quote:

Originally Posted by rusnak

Roger, you might comment on the power and torque difference of the 3.2 w Motronic vs the 2.4 with carbs.

To me, there is no contest.

Yes, but in my case this was tempered a bit by the change in tranny as well. The combination of the Webers and E cams with the 7:31 R&P tranny really made for pretty decent throttle response, especially above 2.5K.

I haven't had the car on the track yet (hopefully this Friday!), but I think this is where the 3.2, combined with a LSD, is really going to shine. It feels like it just wants to keep pulling in all gears, but I just can't take full advantage of this on the street.

Roger