jat930

I am a recent 87 930 purchaser. Mods to date include a g50 (5speed) with modified torque tube etc and s4 brakes front and 930 fronts on rear and upgraded torsion bars, swaybars etc.

I am planning a rebuild and am torn between k27 turbo, larger intercooler, twin plug etc but keeping stock CIS (albeit with a fuel enrichment kit etc), 1 bar boost spring (no electronic boost controller etc) OR programmable fuel injection (eg 3.2 carrera manifold plus ems from say, motec etc)and all the accessories.

Could buy a 993 but the 930 looks so much better !

Any thoughts on rebuild

Geoffrey

I have an 89 with a MoTec setup and love it. If I were going to do it again, I would probably look at the Haltec E6K setup. For about $2000 for the computer, wiring harness, and sensors, you get all you need to run the car as an EFI car (my MoTec was over $8,000). You will spend considerable money ($5000-7000) with someone to DYNO and tune the EFI unit once the engine is rebuilt. Personally, I would never go back to a CIS setup again.

Some things to consider, you can't use your 930 heads because the intake port size is 32mm and the 3.2 carrera intake is 40mm so you will need to purchase 3.2 heads and twin plug them (you could port your 930 heads, but it isn't worth it). Also, you'll need the 3.3 intake, custom intercooler and plumbing (you might buy the tanks and cooler from Spearco and make your own intercooler), and external wastegate. I'd also go with a Mahale 3.4l piston setup which gives you 8.0:1 instead of 7.0:1 bor a good bottem end and use a good set of cams like GT2 cams. Of course you'll want a larger turbo and I like a hybrid from Turbonetics rather than the KKK units. You should be able to get a REAL 500-600hp at 1 bar boost from a setup like that.

Geoffrey

sorry, meant to say 3.2 carrera intake, not 3.3

Steve Weiner-Rennsport Systems

Jat930:

Everyone's goals, usage and certainly budget are different and I'd like to just mention a few things here.

The CIS, suitably modified, will support up to about the 450-460 HP level. Beyond that, you will need an EFI system and you can see from the other posts that is NOT an inexpensive undertaking, assuming that you have someone experienced, competant, and honest in your area who can set it up.

Twin-ignition in any 930 is an excellent idea for many reasons, octane sensitivity being just one. We convert the stock 930 distributor to RSR spec and use a pair of MSD's.

The 930 heads are NOT the same as an SC or Carrera head; the Turbo heads are made from a different alloy that is more heat tolerant. I would recommend having your heads ported and flowed. This is SOP in all of our street Turbo enhancements we do here. Turbo heads are enlarged, flowed & equalized, and machined for the lower plugs before the valve job is done. Intake manifolds are Extrude-honed to the specified port size and flowed to match.....

A properly done CIS twin-plug 3.4 or 3.5 litre Turbo will make 450 real honest HP at .8 bar and combined with your G-50, will make a very fast and drivable car.

Just something to think about,

John from WA

Steve,

Are you putting 3.5's in a 3.3 case? I've heard they tend to leak from some and that they are fine from others.

Thanks,

John
'79 930

Steve Weiner-Rennsport Systems

Hi John:

Although my personal preference is the 98mm, 3.4 litre set, we have done a good number of 100mm, 3.5 litre ones when requested. These do require the case spigots to be enlarged and the heads suitably modified.

Thus far, after 22 years, none of them have suffered any leakage as long as the boost pressure has been maintained at .8 bar.

1 bar is absolute max.

All things being equal, the thicker wall 98mm ones will last longer and maintain a little better ring seal. 100mm ones make a little more off-boost torque.

jat930

Steve & ors - thanks for your replies.

I am really undecided because I will be spending a lot of money to be limited to 400-450HP. However converting to EFI arguably detracts from the character of the 930 (ie in some people's minds, it ends up being a "bastardised" engine).

What is making the decision even more difficult is that I do not want 600+HP and rebuild the engine every 3-6 months.

It seems that a conversion to EFI involves a lot of "additional" money and complexity for an extra 50-100HP.

Regards

Joe

Geoffrey

If done propery 600hp with EFI is very reliable, maybe more so than a 450hp CIS setup. You have to remember that a CIS setup is a mechanical setup and these cars and components are aging. The thing that most often causes Turbos to self destruct is a lean condition. Most often this is a result of too high boost without the proper fueling either by a failing component or self imposed by someone without enough knowledge. The EFI setups are run by sensors and a computer and are in my opinion much more reliable and much more able to be tuned to keep the air/fuel ratio correct under all conditions (air temp, boost pressure, engine temp, throttle position, changes in MAP, etc.) CIS by nature simply is not as flexible. I believe you get better response, more HP, and better longevity from an EFI setup.

Is it worth the cost? To some yes, to some no. My car has 521hp and I've put over 12k on the engine, many of which have been at the track and I've had zero problems. The amount of power this car has still amazes me every time I drive it. I've owned fast cars before and even raced motorcycles. This car is just stupid fast. Is it worth it to me - Yea man!

FWIW, I've heard that it costs about 20K to build a 450hp CIS engine and about 30k to build a 550hp EFI engine.

Jeff 930

jat930,

I have just completed a similar conversion to my 87 930. My project started out of necessity, as my 35,000 mile motor was leaking oil everywhere. Along the way to sealing up the leaks, have done the following: ARP rod bolts; new rod bearings; Racewear studs; RUF 3.4 P&C's with new rings; complete valve job with new guides, CMW springs, seals and retainers; cams; heads twin plugged, CNC ported, polished, flowed and equalized; Carrera intake manifold extrude honed and flowed; rebuilt wastegate w/ 1 bar spring, K29 turbo; Kokeln intercooler; 55lb. injectors running behind 5 bar fuel pressure. All this being controlled by Electromotive TEC1.

I am transferring power to ground through 930 gearbox w/ all new synchro's, lowered 3rd and 4th, and RUF clutch and flywheel (what a kick). Also did some suspension tuning to keep the car/power glued to the road.

One week back on street since dyno-day for testing and tuning, the car is awesome. Still some minor drivability issues related to tuning/mapping the TEC, but it is a monster. Put down 370hp @ 5500rpm and 380 ft/lbs torque at 4500rpm at the wheels (Mustang Dynomometer).

Although I was arm twisted into some of this, it was worth it. Much more responsive throttle, unbelievable acceleration (even without spooling up the boost), and a helluva lot of fun to drive. Mind you, this is still my daily driver (track on weekends), and my wife still likes to ride with me.

My suggestion to your dilema, "just do it"!

Jeff

wydryd

$8000 on a MOTEC SYSTEM? Are you serious? The M48PRO is around $3k (Australian) with all the looms, sensors etc. How did you end up paying $8k? Just curious! If you bought from Australia, it would have cost you (if you're in the USA) around $1500!

Must admit tho, that's the next thing I want to do - rip out the Motronic DME and migrate to a Motec system with pressure sensing for less restrictive intake and finer granularity when programming the various boost/ignition/fuel maps.

The Haltech E6K is suppose to be a good unit, as is the Autronic EMS. However, Motec IS the industry leader with a proven track record. Can't go wrong either way.

Actually, I hear the Autronic has an Auto tune module. All you do is setup some base parameters, drive the car and the EMS automatically creates the various maps for you. No need to dyno tune for hours. Once a relatively basic map is automatically created, you can then take to a dyno and do fine tuning, which shouldn't take long. I believe it uses an A/F Ratio sensor and EGT sensor to do the auto callibration.

Agree with Steve tho, if you want 450+ HP, you'll have to scrap the CIS and go to Digital Injection.

Your car must be a blast Geoff!

Geoffrey

The Motec system was put in the car in 1998 and the prices have come down. However, MoTec nickels and dimes you for every option. Mine has the Advanced tuning option (gives you boost control, more map sites and a few other things), Data logging with 512k, traction control module, the complete 911 wiring harness ($800 list), two coil packs (twin plug)...it all adds up. Just to give you an example, I wanted to add lamda sensing so I could log my A/F ratio and it is a $1400 option for the software password and another $400 for a wide band sensor. $320 for the data cable to connect the laptop to the M48 unit...the list goes on and on. I did hear that this year some of the prices dropped considerable, but still, it IS expensive.

I don't like the Electromodive setup because it has only 8 load sites and 8 rpm sites which I don't feel is detailed enough to accurately map a street driven car. I know PorschePHD used a TEC I unit on his 600hp TT car, but in talking with him, mapping was always a challenge. Although MoTec is the "gold standard", I like the Haltech E6K which is less expensive than the Electomotive setup and is more flexible with a larger number of map sites 16 load and 32 speed and a number of input/output channels. I believe standard tuning on MoTec is 11 x 40 and advanced tuning is 21 x 40 and you can map tp vs rpm, map vs rpm, mass air vs rpm, so it is very flexibile.

MoTec tech support really only wants to talk to its dealers whereas Haltech and Electomotive are very helpful for the DYIer.

Was at my local track yesterday (Lime Rock Park CT) and just had a blast. If anyone knows the course, it is a very small course, only 1.53 miles with a short front straight. I was able to pull 150 down the front straight when exiting west bend at about 90-95. The car is VERY fast. Even with a large single turbo, the boost is controllable and I'm able to come out of some of the smaller corners full throttle on boost with the car hooking up. Every once in awhile I think about a TT setup, but then get back to the reality that this car is just plain fast enough...for now.

Geoffrey

I don't know if I believe all that stuff about "autotuning". First, you really need a wide band lambda sensor to get accurate readings for A/F ratio and even at that, it really isn't accurate much past part throttle application. You really need to properly set up a car on the dyno with a 4 wire gas analyzer and EGT guage. I don't believe in any shortcuts here and after spending 20k for a performance rebuild, I would never take the chance on ruining something just because I cheaped out on the tuning. In my opinion, you need to find someone with a proven track record of installing and tuning (even if you do the installation) to properly set it up. I've only done some basic idle adjustments, cold start adjustments, boost pressure adjustments and some output programming such as a Shift light. I would not attempt to change the basic fuel or ignition maps on the car after it has been set up on a dyno. Even after the dyno tuning, the car is only about 90% complete. The last 10% is drivability and can only be tuned by someone who has experience with your particular EFI unit and application. Just my $.02

Geoffrey

I just checked the MoTec catalog and as follows:

M48 - 2591.13
Adv Tuning - 630.01
Lamda - 1400
911 harness - about $800
Laptop cable - 351
A/T sensor - 154
oil temp - 56
Cylinder head temp - 96
300kpa Map - 57
108kpa Map - 77
Air valve (boost control) - 49
Injectors - 6x162
Crank trigger - 143

That's just a quick example of how much a MoTec system costs add up. You'd still need to add for a distributor, coil packs, plug wires, fuel pumps, fuel rails, etc.

jat930

Dear All

I am in the process of "researching" and "costing" a MOTEC or HALTECH ems. From my perspective, either is handy having an Aus presence. I will post results.

Interestingly, my local engineer did mention that generally, once you move to ems like MOTEC in 930s, some drivability issues always arise (in his opinion) because as a matter of practicality, the programming is never sufficiently comprehensive because of the time & costs & testing environments involved to get even close to 100%.

I guess if you did convert CIS, the next question is why stop there ? Why not then(a)TT the 930, (b)add coilovers and c)big red brakes. At this point (IMHO), I am starting to have difficulty still calling the car a 930.

Unless the costings are suprisingly low, Steve W's comments (which are consistent with my local engineer) seem convincing: a 400-450HP (CIS equipped) 930. At the end of the day, I can honestly still call this a 930. Although a dream, having a 930 AND a 993TT which I can modify to my heart's content may be the panacea.

Regards

Joe

Geoffrey

Joe,

I'm not sure where the concern of "is it still a 930" is comming from. In my opinion, upgrading your Porsche using any available Porsche equipment is in line with Porsche's philosopy when increasing the performance envelope of its street cars. Traditional, as the hp increases so does its brakes, suspension, etc. My car is every bit a Porsche and any other. With the exception of the fuel and ignition management, the upgrades use mostly Porsche parts. Anyway why does it matter? I can tell you that once you get a serious hp engine in the car, the chassis and brakes can't handle the power. The stock suspension, when the engine came on boost it bottomed the stock suspension. I upgraded to stiffer t-bars, sway bars, shocks and its all better. Yesterday at the track I was noticing quite a bit of fade in my stock brakes due to the high speeds and heavy braking, so I'm going to upgrade to 993TT brakes. The oil temperature of my car was running higher than I would like so unfortunately I need to buy a center mounted oil cooler and upgrade to an aftermarket spoiler (930S). Bottom line is that you really can't modify one component and expect the others to keep up. At the end of the day it looks like a Porsche, smells like a Porsche, and drives like a Porsche so it must be one.