Long block questions.

[Noah Holcomb]

I have owned a 1985 Turbo Look 911 for just over 5 years (the car only has 54K miles) and I finally want to step up in terms of power. I have also owned a very fast Turbo Buick (10 second in 1/4 car) and after years of ownership I am fed up with the constant electrical problems that seems inherit with every Turbo Buick, along with the car's boat like handling, substandard brakes, and so many other aspects I just don't want to deal with. While that Turbo Buick had many problems it spoiled me in terms of sheer power and acceleration. My Porsche on the other hand I am very happy with its handling, brakes, and overall design. I just want my 911 to have more power, about 3 times the current output!

I had Accel DFi on the Buick and I think for the Porsche I would like to use a motec m48 for control of the fuel and ignition. I think I have a handle on turbo selection as well. The area I have the most questions with is building up the long block itself for this project. I want to make an honest 600 hp to the wheels running C16, I would really like to make this power level on 100 unleaded or 100 low lead AV gas but I realize that may be a bit of a pipe dream. I want to use the 3.2 case, heads, and most likely crank. However if another crank is recommend I would consider using it. I want as much displacement as reliably possible; could I go to 3.4 or even up to a 3.6 without any adverse effects?

I would like to know what diameter pistons, and cylinders are recommended along with the best rods to use (I was thinking of going with the JE pistons and cylinders, and the Carrillo H beam rods.) Also how much displacement will this combo yield with the 3.2 crank? Also what other crank could be used and how much displacement gain would the engine receive?

How important is the twin plug conversion at this stage and why is it so crucial? (From my push-rod V-6 and V-8 background extracting massive amount of power reliably with just 1 plug per cylinder is an easy task)

What cams are most people running in their turbo engines at the power levels I am looking for?

Any help is appreciated.

[turbobrat930]

one phrase to remember...... search , my young friend, there is much to learn!

You have about 40 hours of reading that you need to do... look at all of the past posts on this board for the past two months or so... read the topics, you will find most of your questions have been already hashed out... Call some reputable shops...and beware of a couple ( read the past posts for the answer to that one), ask the shops what they recommend.

Welcome to the board... and yes, 600 is definatly do able, but you will spend some money to get there. There are several combinations of parts ( rods, cams, pistons, etc,) that will work, you will need to choose.

It would help to know what part of the world you are located, as you really need to find someone close who knows these motors, and knows the EFI system you will be going with, like the back of his hand.... that is one of the most important things.

[Noah Holcomb]

I am in Chattanooga, TN. I have a friend with vast experience tuning engines that use Motec systems, and I have experience with Accel DFi from my Buick and it like all the other stand alone fuel/spark systems go about accomplishing the same basic task they just use different interfaces. I am not really worried about controling the engine once it's done, I just need to learn more about building up the long block. I did a bit of searching but I will do even more.

[turbobrat930]

MoTec is an excellent choice, abiet very expensive, but if you have a guy in Chat, Tn that knows MoTec, then that is a no brainer.

I juast rebuild my 3.3 and with 98mm P & C's, and a stroked crank, it now resides at 3.6L. Bumped up the compression to 8 to1, twin plugged, 3.2 intake, extrude honed, GT-2 EVO cams, port and polished heads, opened up the intake and exhaust ports, comp. valve train, custom equal length headers, GT-35r turbo, huge full width I/C etc....using a Link EFi system, we will be well in the 600 HP range... I am about 2.5 to 3 hours south of you in Macon, GA...pm me for my Phone number...if you would like to talk more...

I used JB racing in Fl...

here is the post on my rebuild...

another 930 rebuild....It is FINALLY coming together!!!

[NathanUK]

Welcome to the board Noah. Some pics of your car would be nice !
Lots of info to read here.

[WydRyd]

There are many 3.2 turbo converts on these boards... do a search my friend

My car started out as a M491 Carrera too, then I got the HP bug and did a turbo conversion on it and haven't looked back

As mentioned above, 600 is attainable, but be prepared to spend some serious $$$$$ BTDT!

[Noah Holcomb]

Old picture of the back of my 911.

[930gt-40r]

Hey Noah, Im using the Accel Gen VII in my 86 slantnose. And guess what car it was origonally intended for? Buick Grand national. I have it all hooked up now and Im waiting for Job Spetter (you probley know the name) to sync the distributer and setup a base map in her.
So if you know accel dfi and have good experience with it, I would say go with what you know.

[Noah Holcomb]

I used the old GEN-6 DFi on my T-Type. Mine was the fully sequential unit that handled low impedance injectors with ease unlike the Gen 6 bath fire ECU (my Buick had 83 lb/hr. injectors ) GEN-7 is light years ahead of the GEN-6, the DOS based software was honestly outstanding when the final revision made it's debut, but that was back in 1993! The newer systems make many things so much easier. More data, more analysis (no longer do I have to print out values and enter into excel or mini tab) Data acquisition is vastly improved with higher sampling rates, more data logging capability, and much better logic for varying of the fuel/ignition maps during undesirable/unpredictable scenarios. GEN-6 DFi did not even have an option for a wide band O2 sensor, this can make tuning very frustrating at times. The old DFi can typically get the job done just as good as the newer systems but getting it to that point is much more time consuming and it is a lot easier to unintentionally mess up along the way.

Like many other Turbo Buick owners I never used a dyno to tune, most Turbo Buick owners just tune at the drag strip. Not the best way to do things but it worked. I will get a good bit of dyno time on this Porsche as I am not interested in merely sending this car at wide open throttle down a 1/4 mile of blacktop. I want the engine to do well in all scenarios.

I want to do the majority of the tuning myself (starts out because I am cheap, ending up I will spend so much time it would probably be more effective to take it to someone and just pay them ) I have looked at the new GEN-7 Accel DFi, the MoTeC M48 and M600 systems, several Haltech products, F.A.S.T, SDS EM-4 6F, even the DIY MegaSquirt system.

[930gt-40r]

I like Haltech and Motec, Im just using DFI because one of my friends did it on his 900 horse twin turbo and I had some kind of model to look at, although I made many little changes to my car for what I think is an improvement (Im not getting 900 hp, but I dont have the pockets or know how that he does). If I had to do it all over I would have gone Haltech seeing as I dont have the ching for the Motec unit. But this Accel set up is pretty simple, even if the wire harness is for a G-National. Plus I also heard that the DFI is very reliable.

[Lukesportsman]

I have Gen VII on my 69' Mustang and have been reasonably happy so far with the start up. I had SDS before going back to the days of laptops being expensive. Showing my age

Noah, you know that Accel has a sequential dizzy out for the Porsche now to go with DFI right? I have the sequential distributor in my Mustang and it was quite simple to install if your staying with 6 plugs.

[WydRyd]

Originally posted by Noah Holcomb
The area I have the most questions with is building up the long block itself for this project. I want to make an honest 600 hp to the wheels running C16, I would really like to make this power level on 100 unleaded or 100 low lead AV gas but I realize that may be a bit of a pipe dream. I want to use the 3.2 case, heads, and most likely crank. However if another crank is recommend I would consider using it. I want as much displacement as reliably possible; could I go to 3.4 or even up to a 3.6 without any adverse effects?

I would like to know what diameter pistons, and cylinders are recommended along with the best rods to use (I was thinking of going with the JE pistons and cylinders, and the Carrillo H beam rods.) Also how much displacement will this combo yield with the 3.2 crank? Also what other crank could be used and how much displacement gain would the engine receive?

How important is the twin plug conversion at this stage and why is it so crucial? (From my push-rod V-6 and V-8 background extracting massive amount of power reliably with just 1 plug per cylinder is an easy task)

What cams are most people running in their turbo engines at the power levels I am looking for?

Any help is appreciated.

Noah,

The 3.2 crank is the same as the 930 turbo crank, so are the rods, so you won't have any issues with strength or durability, as long as you aren't raising your rev limit to something like 8K RPM's

IMHO, if you are going through a complete rebuild and have the money for it, this is what I'd recommend you do:

- 98mm P&C's (7.5:1)
- 993/964 crank to increase low end torque and capacity (~ 3.5L) (but this adds $1500 to your build!!!)
- GT2-EVO CAMs
- larger piston splash valves
- 930 turbo oil pump
- ARP fasteners
- flame-ringed cylinders/heads with aluminium sealing rings for best reliability at big boost levels
- twin plugged heads for optimal combustion

As for turbo selection, that really depends on how much power you are looking for, but if you are after a tonne of power, I'd recommend a GT40R and a set of 1 5/8" headers.

If you want optimum spool and power, then perhaps go with a twin turbo setup with 1 5/8" TT headers and a pair of Garrett GT38R's (or RS's).

As for engine management, there are many options, but for true drop-in plug'n'play on the OEM loom, I recommend the Protomotive modified Motronic ECU, which uses MAP sensing, instead of a MAF/AFM based system. If you have serious cash to spend, then Motec is the best and most expensive, but will require substantial tuning.

Interesting project! Keep us posted