Help me choose the next steps for my EFI Turbo Conversion
 

Hey Guys,

I did a pretty basic turbo conversion on my '87 Carrera a few years ago. I've since decided to move forward with an aftermarket EFI conversion. I've been collecting parts over the past few years, and I'm getting closer to starting the project work back up! Here's a quick recap on some of the internal mods that I've already completed:

1. ARP Rod Bolts
2. Supertec Head Studs
3. 930 Cylinders w/ 8.0:1 Pistons
4. Twin Plug Carrera Heads

One of my constraints for the conversion is that I'd like to keep the body 100% stock. I'm keeping the Carrera tail and A/C. There's plenty of debate on the topic, but I've decided not to shoehorn an air-to-air I/C under the tail. For better or for worse, I'm going to follow the lead of fellow Pelican thechiller and use a water-to-air I/C. I'm probably going to install a large under-body radiator in conjunction with a wheel-well radiator w/ a high flow fan. It adds weight and complexity, which are acceptable to me.

I have an Electromotive TEC3-R engine management system with a twin plug direct fire ignition that I picked up for a decent price. I don't have much in the way of the fuel system sourced yet. I've got new Bosch 55 lb injectors, and I'm planning to upgrade to a Bosch 044 fuel pump. I've got a set of AMS custom made headers w/ a T4 flange (thank you YermenCars!). I'm leaning toward a Precision SC6262 Turbo w/ T4 .68 A/R hot side. The guys at AMS have had success with the headers/turbo combo on turbo Carrera conversions, so I'm inclined that direction. My goal is to achieve 500 HP w/o exceeding 18 PSI. From what I've read in this forum, conservative opinion is that you should flame ring the heads after 1.2 BAR of boost, as they tend to lift off the cylinders. I'm not looking to set any records, so I'd prefer to play it on the safe side.

I'd like to hear your input on my build plans. Am I missing anything that I should be considering? A few specific questions I'd like to run by you guys:

1. Will extrude honing my intake manifold be beneficial even if I don't port the heads given that I'll be dyno tuning the car? How about porting the intake manifold? Is that different than extrude honing? I'd prefer not to tear down the entire top end for further upgrades.

2. I've heard of several TurboKraft builds that are running 964/993 twin knock sensors. I believe the stock 993 bridge is used on one of the cylinder banks. Can this bridge be installed w/o tearing down the engine? Or does it require that the cylinders be machined?

3. What do you recommend in terms of the fuel system for my setup? Do I need to replace the stock fuel pressure regulator, fuel lines and fuel injector rails?

4. What else? I'm sure there's something I'm missing :)

The car is in the shop right now getting a suspension refresh and upgrade. Stiffer torsion bars and Bilstein Sports. Big brakes coming in July.

Thanks for help!

Sounds like an interesting project with some twists.

Several years ago I polled the guys on this site who had high HP engines. I was looking at the impact of twin plugging. In the process I found their engines all fell in orderly fashion on an old Porsche engineering chart of boost vs. geometric compression ratio.

All were running at roughly 12.5:1 effective C.R. on available pump gas. Represented was 7:1, another 7.5:1 and then 8:1C.R. At your chosen 8:1 compression ratio, 1.2P.R. is in no mans land but your goal of 500HP was demonstrated at .8 bar so the high boost shouldn't be needed.

fire rings
 

Andy, what kinda power does the car make now and are you looking to get 500hp/500tq at the wheels?

I'm by far no expert on these 930s, but I have fire ringed heads going in my current build and just based on the stock fitment of 930 heads to cylinders I'd suggest doing it cuz stock is pretty loose and once they move there goes your seal...RC
http://forums.pelicanparts.com/uploa...1308928330.jpg

Very encouraging! If I can achieve 500 HP at a lower boost level, then all the better! I prefer greater reliability over greater performance. I think some of the advantages of my setup are the Carrera intake manifold, Carrera heads and 8.0:1 pistons. This should flow well and require less boost to make power. I'd love to be able to cap the boost at .8 BAR and have the engine run reliably for years to come.

Thanks for the input. Based upon the feedback above, it sounds like I won't need to go up to the 1.2 BAR territory to achieve 500 HP. Also, I'd prefer not to tear down the entire engine.

I don't think my HP goals warrant porting the intake and heads as the Carrera intake is 41.5 mm and the cylinder head inlet is 40 mm. Even ported 930 heads are smaller than this. Thoughts?

A couple easier-to-complete upgrades would be a larger throttle body and extrude honed intake manifold. The Carrera throttle body is 63.5 mm in diameter, and it can be increased to 66.5 mm max. I've read about a handful of guys in this forum who have converted to Mustang throttle bodies that are around 75 mm in diameter. Are there any proven solutions out there for putting a larger aftermarket throttle body on a Carrera intake manifold? Any words of wisdom on the value of a larger TB or extrude honed manifold?

You can skip the E-H and porting, not necessary at this level.
Fitting a larger throttle body is not only unnecessary, it's usually brain damage. Skip it.

Stock 964/993 bridges, and updated 993 sensors. It requires removing the heads for machining.

A single 993 GT2 (-044 fuel pump) will suffice for 500hp (~450rwhp), but 2 pumps in series ala 930 is better -- plenty of pressure and volume. We've made 600rwhp on 930 fuel systems with stock Carrera fuel rails and a Carrera fuel pressure regulator.
-044 pump adapters available from TurboKraft,

500hp from a 3.3L is easy: headers, muffler, decent mid-size turbo, decent mid-size intercooler, mild cam upgrade, mild head work, EFI. If you don't make at least 450rwhp on pump gas, you're doing something wrong.

My $.02 on this... OFF BOOST, there is a noticeable difference to me using EH Carrera intake and 71mm TB. The car is much more responsive to throttle inputs AND smoother in general v/s before. Is it worth the extra expense? Depends on how you use or drive the car I suppose. To me, it makes for a nice street/cruise driving experience.

Thanks for pitching in Chris. Out of curiosity, what trouble have you seen with fitting larger throttle bodies to 911s?

I completed a rebuild about 5K miles ago, and it's shaping up that the only reason I'd need to break the engine down again is to machine the heads for knock sensors. Are there any alternate mounting positions for the sensors that don't require machining? Or is this a must-do in your mind?

Wow! Good to know the Carrera fuel system is up for the task. Do you think that Bosch 55 lb injectors will flow enough fuel? I'll plan to source the pumps and adapters from you as I get closer to the conversion date.

I was planning to use my stock Carrera cams. I've heard several success stories from engine builders that have used these cams including Supertec and AMS. I believe the grind is identical to SC cams, and that it's the cam timing that is different. Do you have any concerns on using Carrera cams?

Thank you!

I ran 42# injectors up to 8# boost with AFR's at 11.0 just hitting 85-90% duty cycle. You have to remember that the Carrera FPR runs the fuel pressure at less than the rated pressure for the injectors so your effective flow is less than 55#.
I have a single knock sensor mounted on the crankcase vent cover and seems to work OK. Given the choice, I would add the bridges and go with 2 sensors which is probably what I will do when I next tear down the engine. It is good to know you can machine the heads to fit the bridges which are inexpensive and not have to source custom cylinders.

I have seen reduced acceleration at WOT on a 3.2L Carrera, plus the drivability wasn't as smooth. The theory is because this had a 3" throttle body grafted on, there were 2 issues:
- the progressive nature to the throttle linkage was gone -- the installer just made it work, no care about the first ~50% of pedal movement opening the throttle only ~25%
- manifold vacuum went away faster because every degree of throttle opening is allowing in more air than the system was tuned for. Maybe if the car had a programmable EFI system, it wouldn't do this, but the original Motronic didn't take it well.

Up to you. We now add the knock sensor boss to all heads standard unless requested to leave it off.
I have seen some people use one sensor on the throttle console stud, maybe with the J&S knock unit. I can't speak for how effective this is.

The injectors should be large enough for your power goals.

They're fine, too.

Wish TurboKraft was in my area!! Very cool to read your Feedback on this Chris.

I recently got a quote for Motec, the pricing wasn't too bad but I was skeptical about their Porsche knowledge even though they claimed to have fitted them to dozens of 930s...

The cold start, hot start mapping etc issues I hear of people suffering scares me, I don't want to turn my very reliable system into something high maintenance. It's why I was considering the MAP2ECU piggy back computer, I actually bought one.

How feasible is a remote AEM installation provided by TurboKraft, impossible I imagine with tuning?

Your pricing on a Motec M600 should be excellent: they're made there in AU. If anyone should be able to dial in a *perfect* idle, and have no boost fluctuations, it should be Motec AU. If they can't...

Long distance on the AEM isn't scary. There's a huge online forum to help you with the common questions. And another gentleman in Melbourne with a 1994 Turbo 3.6 bought a system, installed & tuned it. PM me with your info and I'll pass it on to him.

Thanks Chris, Motec don't actually install the systems themselves here, there's just tuning shops around that install them for you. Not sure if they even need to be authorised. Still Motec seems to be about double the price of other systems I've seen.

So you can provide a system that is kinda plug and play?

Thanks I'll PM you my details, hopefull he has time for a chat!

You might try Andy at Adaptronic in Sydney, great system and I'll bet whoever the CEO of MoTeC wont come to your house and set it up for you.