944Turbo build plans

Hey gang, planning a build for heavy race/track use and interested in some input from the pros out there.  As for donor engine, selection is between a LS1 GTO and f body LS1.  Understand both have there challenges (but easiest relative to other LS engines), ie GTO doesn't allow stock wire harness to be used plus alternator change and it seems like there are some added expenses with the quicktime BH vs a C5 BH (although not entirely sure-would think all the LS1's have the same bolt pattern, can anybody confirm?).  Can someone chime in on the integration challenges/expense of either?  Also when selecting the donor engine want to ensure I request every accessory that will make use of, for instance, slave cylinder, wire harness (if it will work).  The knowns are that the stock oil pan and exhaust headers won't work on any of these stock engines in the 944).   This is what I've come to appreciate so far (interested in input on either engine-gto LS1 or 5.7 f body engines-cam/fire-b):

1. Slave cylinder adaptation- hear the wilwood slave cylinder kit has reliability issues.  Are folks out there using the stock clutch (non-spec) for track use  with reasonable success?  Would think by using the stock clutch with stock slave cylinder all the way back to the pedal would be most economical and reasonably reliable.

2. Adapting LS fuel rails to 944 fuel lines.  An kits out there or are folks using mom and pop hardware.

3. Aftermarket Radiators and oil coolers-what are the track guys using with good success?

4. Are most guys using manual racks to free up space between the x brace and oil pan?

Thanks in advance for the input!

I have an 04 GTO engine, no need to change the alternator, unless you want a less powerful one, the GTO's is 130A or so. The wiring harness isn't that hard to modify, you just take out what you don't need from the body control module. As far as I know all LS1's have the same bolt pattern for the bell housing. There is some chatter on LS1tech that the GTO has a different cam and more aggressive tune than the Camaro, but probably doesn't make a noticeable difference, and most likely you'll re-tune your ECM anyways.

Some of the track guys can chime in on your other questions. Good luck with the project!

Regarding the engine choice, depending on the build date of the F-body LS1 it may or may not have the LS6 block which as some minor improvements such as the windage ports between the cylinders. Also if its an older f-body (i think pre-'01 model year) it will not have the LS6 PCV and LS6 intake manifold. Like 87-944S the engine in my car is from an '04 GTO.

If you go with the GTO motor, i would recommend not using that engine harness. The routing of the harness goes towards the drivers side if i remember right for the GTO, so its not a great fit. Also the GTO engine harness integrates part of the body harness, so its alot of extra wiring to be cut out. Secondly, the GTO harness uses a different PCM; i forgot which code PCM it is but its the green connector one that from what ive read is not as flexible as the 411 PCM (red / blue connectors). I sold my GTO PCM and harness for a few hundred bucks and bought a 411 PCM (sub $100) on eBay and a new standalone engine harness from PSI. The PSI harness is extremely easy to hookup and also has the advantage of being new! In my opinion its worth the extra $ for less of a headache.

1. I cant comment on a stock clutch for track use but i dont see why you would have any issues at stock, or near stock power levels. If you decide to bump the power up, the LS7 clutch seems to be a good choice for basically stock like pedal feel and engagement and more holding power.

I am using a Spec stage 2 setup which isnt bad at all even in traffic. I am using a Wilwood compact type clutch master cylinder and honestly i have not had a great track record with longevity on them. Granted i did have a few bugs to work out on my mounting setup which killed two of them prematurely, but ive noticed the new one i put on with about 1k miles on it is starting to weep fluid again from the rubber boot (this was after i thought i worked out the bugs). This could be related to the way i have it mounted in the car though (angle could be off). I think this is one part i will have to revisit down the line to make improvements on.

2. The fuel lines are fairly simple to hook up. The only decision you really need to make is using a return vs a returnless system. The return system is the most easy to hookup i think because you reuse what is already on the car, just convert the existing hard lines to AN fittings. I dont think any stock LS fuel rails use a return type setup, so you will need to buy a set of billet rails and a external fuel pressure regulator.

3. I am using the Renegade hybrids radiator. Fitment is ok, but it requires cutting out the top part of the mounting frame. Not a huge deal, but not a bolt in solution. The radiator has no problem cooling while on the track or during normal driving, however i have experienced its ability to cool at idle to be limited by the electric fan. Due to the thickness of the radiator core, you are very limited to fan options. I have the strongest fan i can fit with this radiator and i watch the water temps religiously during stop and go traffic or extended idling. I have never over heated or come close to over heating at idle, but its performance is not the best which is why i watch it so closely. This would probably be alleviated by having a proper shroud made for the radiator core.

Admin on here (Texas Performance Products) was working on a radiator that looked quite nice, but i havent heard much else about it since a few pictures were posted a while back.

For the work that was required to fit the Renegade radiator and its short comings with fan clearance and lack of shrouding, if i had to do it again i would probably have a custom radiator made by a local fabricator.

4. Manual rack certainly clears up space but the power steering doesn't add too much excessive 'bulk' i think. I posted some information a few months back about redoing all of the high pressure hardlines with AN braided hose so everything clears the rack nicely.

Appreciate the response guys! Interesting stuff...LS1 GTO with f body brains and aftermarket harness, presume this was the harness you went with TEchno:

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The LS7 seems like a good way to go, they look reasonably priced only issue I can envision is with the slave cylinder.  If its anything like the 944 with shared hydraulic reservoir with the brakes, I could route the LS slave cylinder line up to that point and keep the 944 line up to the reservoir.   This bypasses the complexity of appropriate mounting of the slave cylinder since the LS slave bolts right up to the C5 bell housing.  Techno, are you using a C5 BH or aftermarket?  It had appeared on some installs the quicktime BH due to its excess thickness didn't allow sufficient engagement of the spline and some were having to push the torque tube forward for adequate engagement.  Sounds like a real hassle to be avoided.

Anybody using the LS7 clutch w/ C5 BH?  If so, what was a robust solution for the slave cylinder?

Fuel lines/regulation.  Looks like there are some reasonably priced kits out there, Techno, did you happen to use the FAST146032 kit?  Were you able to reuse the stock 944T fuel regulators or did an aftermarket regulator make more sense?

Cooling.  Yes, I've been in discussions with both Kent and Eric at TPC, and it looks like they have a "bolt-on" radiator.  I'm planning to run 2 aux oil coolers and was going to attempt to forgo the radiator fans.  THe 944 ones at least weigh a ton and the time I spend at idle in racecar is pretty limited but interested in input from those track junkies out there.  Perhaps there's enough time in the paddock area for a fan to be warranted.  If so, I would use a lighter aftermarket one, which fan do you use Techno?

Thanks.

Also, is there a good reason to select the earlier LS1 GTO over later the LS2? Just looking for some flexibility in choices out there. Alot of high mileage engines out there, and if not, be suspicious!

Techno, just thinking up questions as they come...was the reason for going with the 411 brains was to go drive by wire. My understand is the throttle response is preferred mechanically. I hear the GTO brains work just fine so interested in what advantage you saw in the 411 vs. the the pcm that came with your motor.

Anybody using the standard wilwood master cylinder that is steel lined? This is apparently better than the fully aluminum compact one folks are having issues with.

Haven't seen anything about TPC's radiator. Lots of guys are either using the Wizard radiator of the RH/Ron Davis radiator.

I have the Ron Davis one and it works fine, I'm using it with dual 11" electric fans. No issues.

For brakes I'm using the Ford Hydroboost, other choices there are the BMW or Porsche hydroboost.

I used an f-body 411 PCM with a throttle cable and Painless wiring. Later LS2 GTO brains use DBW, you need the gas pedal and a more complicated wiring harness.

A fuel pressure regulator is integral with the LS1 fuel filter. This is a super easy way to go.

And be careful in deleting rad fans. When I come off track the fans whir-away on high for quite a while dissipating heat. I'm using stock n/a 944 fans but am thinking about trying a pair of Spal fans that might open-up airflow at speed. She runs hot on a 90+ day.

Rich

05 and later GTOs are DBW and 6.0L, 04 and earlier are cable and 5.7L. If mine came with DBW, I would have used it.

This is the harness i went with; it is for a manual trans car so the wiring for the VSS is included.

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As stated already the GTO LS1 is a drive by cable, it was the LS2 that went drive by wire. The 411 pcm is meant for a cable type setup, this is the pcm used on the f-body, trucks...etc. It was a matter of simplicity using an f-body type engine harness with the 411 pcm. The 411 pcm has the benefit also of being slightly more flexible i read in tuning options in regards to what can be turned off / on, changed...etc. The LS1 is just a lump and doesnt know the difference between what combo of parts your using.

For the bell housing, i am using a C5 2-pc bell housing. I have no experience with the QuickTime bell housing but my friend (user Thom on here) built a car with one and i think one of the difficulties he had with that was checking the engagement of the torque tube input shaft into the pilot bearing. This has to checked regardless of what bell housing you use, its just a little more difficult to check correctly with the QT bell housing. Regardless, it is very easy to adjust the engagement of the torque tube input shaft if needed.

My clutch setup uses a separate hydraulic reservoir from the brakes now. The LSx uses a hydraulic throw out bearing which is basically also the slave cylinder (all 1 piece). This bolts directly to the bell housing as you noted. For this, just use a generic C5 vette slave cylinder. It is not like the 944 setup that uses a slave cylinder acting on a throwout bearing. What has caused trouble for some is finding a clutch master cylinder that fits, displaces enough fluid to fully disengage the clutch and also does not have crazy pedal effort. Fitment also requires the angle of the master cylinder be correct..etc. This is one of those parts of the swap that is a bit tedious to get right... getting the engine in is easy, stuff like this is what takes alot of time. If i could do this again, i think i would have went with a Tilton pedal box...and its something i may do in the future still. This way i can eliminate the hydroboost and clutch master cylinder setup i am using. The setup works, but it has some bugs to be worked out i think still. The Tilton setup would be quite a bit of work to get installed initially, but quite simple in terms of operation once install is completed.

What part number for the steel lined master are you looking at? The Wilwood master cylinders are a copy (or atleast a clone) of the Girling compact master cylinders. I tried using a Girling one thinking the build quality would be better...made in China vs made in England. However the custom mounting bracket i am using does not allow for the Girling master to be used without totally reworking the design as the body of the Girling master is slightly different. Basically the bracket i am using (from user 944convert) was designed to be used with a Wilwood compact remote body.

I am using Aeromotive fuel rails, but really these are all exactly the same. I went with a rail though that uses o-ring boss on the rail rather than a pipe thread... this is the inner (super anal) engineer in me. Not worth reusing the fuel pressure regulator as the fuel pressure the LS1 calls for is different. I just used a generic Aeromotive fuel pressure regulator and set the pressure as needed. It was super simple to hook up for me, i was using a billet rail on my turbo motor and had all the lines setup for AN aswell as the adjustable FPR hooked up. Literally all i did was hook the lines up to the LS1 fuel rails and adjust the fuel pressure as needed.

For fan i am using a 16" Spal slim fan. Forgot the part number but its the most powerful slim fan they make. Two dual fans would do better but i havent gotten that far with it yet.

Check out my build thread for some ideas on how i did things. There are a bunch of ways you can go about doing this swap, look at some of the other build threads also to get ideas and guidance. Without other users experience posted on here i probably wouldn't have gotten my car running as well as it does.

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I've got the QuickTime bell housing. No issues with lining anything up with it.

Pros:
True bolt in bell housing, no special machining adapter needed
Integrated scatter shield so you don't lose body parts if something blows up in the clutch area

Cons:
Heavier than the 2 piece C5 bellhousing since it's steel and not aluminum
Since it's a 1 piece bell housing it's just as hard to change the clutch as stock, vs the 2 piece housing giving you a bit more play

Honestly I wanted the strength and direct bolt up that the Quick Time offers. I wanted as few, one off, special machined bespoke pieces on the car as possible. They open the door for failure and will be a PITA to replace vs an off the shelf piece from a large company.

I've had it on the car for 5 years with not one problem.