I blew up my Porsche! (We found the Weak Links on the Path to 1000whp and beyond)

Video link can be found here

We found the weak links the hard way on our Path to 1000whp and beyond!

We were recently asked in the comments of one of our other videos “ We would like to know what the weak links are and what their limitations are, ie, hp/tq limits, ecu.”

So, here’s a build up from basic tuning to wild builds hitting weak links at each step.

These engines were originally developed in the Porsche Gt1 car that had quite the winning streak through the 90’s.  The 996tt engine is basically a detuned version of the GT1 racing engine.  And as commonplace as 1000hp street cars are these days, you may be surprised to find out that the racing engine produced only 600hp at the crank!  So, what we’re considering weak links now weren’t even obtainable at the time the engine was designed!

Even the street version of the GT1 produced only 536hp, which these days is barely a mild tune, lol…

That being said, there is a path to quite reliable high power in these cars.

Top 10 roadblocks to the upgrade path that must be taken down to move forwards.

1. With the cars producing 410hp from the factory, a simple tune can quickly take them to the limits of the turbos around 460-480 hp depending on the quality of fuel you’re running.  The 25lb compressors on these turbos can net closer to 500hp theoretically, but the restrictive exhaust curbs that a bit.  So a Proto tune and x pipe can get you to 500hp, but you just can’t make much more power due to the turbo limitation unless you were running nitrous or nitromethane that carries its own oxygen in the fuel 🙂
2. With a turbo upgrade, ie k16/16g, k1665g2, k1668 or more, you’ll have enough turbo for nearly 700hp, but won’t make it because you’ll run out of injector somewhere around 540-560hp.  Yes, 40lb injectors x 6 cylinders / 0.5 bsfc is only 480hp, but that’s rated at 3.0 bar.  At 3.8 bar you’ll gain about 12.5% more fueling for 540-560hp.   So, let’s throw in a nice set of 80lb injectors to double the power capacity just for fun 🙂
3. Now you’ll run up a bit more to just over 600hp where you’ll hit a few more roadblocks.  The clutch is one, so we’ll throw a 764 or 487 sachs pressure plate and lightweight flywheel setup to hold it a while longer then run out of fuel pump..   For the fuel pump we’ll put our single Walbro 450 drop in pump in the tank and continue on.
4. Well, the intake starts becoming quite restrictive here.  To handle that we’ll put a pair of our fenderwell intakes and billet blow off valves in along with a nice set of Proto intercoolers, y pipe, 74mm throttle body and a plenum.  Just to be sure we’ll be good for a while.
5. In the low / mid 600’s the fuel starts becoming an issue, not due to flow, but more due to the combination of octane, boost and compression ratio getting cranky.  Ms109 or other race fuels are a nice, but expensive solution.  Meth injection is a lower cost solution with its pros and cons.  E85 is fantastic, when available.   But any of these solutions allows us to take this engine a bit further.
6. However, in this range we start reaching the limits of the rods and head studs which both tend to fail right in the low to mid 600 ft lbs of torque.  996tt engines tend to make similar power to torque numbers with a stock intake manifold, ports and cams, so we’re kind of stuck here for a bit unless we boost-ramp.  With oem boost control, or an aftermarket boost control with boost by rpm we can bring the torque right up in this range and ramp the boost to maintain the torque from falling off.  We recently did a race car for a client that another shop built a nice 3.8 for him but only updated to 10mm aftermarket head studs.  So we had to limit the torque to 800 ft lbs, which it was able to hit quickly around 1.4-1.5 bar on e85.   But with a boost ramp we were able to produce 1000whp on that car and meet his goal for power without having to tear the engine down again.  So, on the low/mid 600 ft lbs limit we’d ramp to 750-800hp if you’d like to push it that hard.    It certainly makes for an exciting car that feels like it’s never going to stop pulling, kind of gt3 style.  But will lack that smack in the back torque feel that everyone loves so much with turbo cars.
7. So, let’s go inside and upgrade the internals with some Proto Rods, 12mm head studs and some cometic gaskets.  Just a basic build.  Not changing the power curve, but a strengthening build so we can continue the story.   While we’re down here, let’s not forget to follow the Porsche TSB about the oil gallery plugs and stake them so they don’t randomly fall out.  We’ll also be checking the intermediate shaft gear and prepping it for some higher power.
8. At this point we’re out of turbos again.  So let’s throw some Xona XR1100s, Garrett gt3076’s, EFR 7163’s or whatever your flavor happens to be. 
9. But we’ll run out of fuel again due to the tiny oem fuel line, somewhere in the 800-900 range.  We’ve made over that with series’d pumps helping out with the pressure drop, but it’s much better to just upgrade the line to an 8an.  If you’re running E85, you’ll be wanting to drop the 2nd pump in our dual Walbro drop in pump setup and finish off the fuel system with all teflon hoses and bump the injectors up in the 1650cc range.
10. And unless I’m missing something.  We’ll be able to tune you up in the 1000whp range.  On a strengthening only build, this will be taking somewhere around 2.2 bar of boost.

But we’re Protomotive 🙂  So, let’s make it better!

Bonus!

11. Let’s go back to the engine.  We’ll throw an 80.4 crank, proto rods for stroker cranks, our 103.6 p/c’s and come out with a 4.1L engine.    While we have the heads off, we’ll port the intakes to GT3 spec, upgrade the valve springs and change out the intake manifold for a gt3 intake.   This is our “cookie cutter” big build that we love so much and was featured in the Roads Untraveled video “we found a 1000hp Porsche where you’d least expect it”
12. With this build, we’ll need to revisit some of the previous upgrades.   We’ll update the clutch to our Proto dual clutch to handle double the power of the sachs 764 / 487 setup.  We’ll also be running out of turbo if you want the power to go  up over 1000whp and change.  Although this setup is amazing for a street car!   The response and torque is better than the factory car with tiny little turbos on it, but with 2.5x the capability now.  The power under the curve is just monstrous.  It’s truly a great setup.
13. For those that want more, we upgrade the turbos to gt3586hta for 1200s, Xona XR7864’s for 1280-1300whp, or for stupid power we did some gt3794’s and ran a 4.2 with the same build but an 82.4 stroker crank vs. 80.4 crank to over 1500whp.
14. By the way, we’re still running the factory ecu!

Bonus round 2

15. Still want more?  Rather than throwing more boost at it, let’s use rpm’s now.    Let’s go back to the engine, and change the heads, cams, lifters and actuators over to full gt3 parts.   With the super low mass of the gt3 lifters and huge cams, we can now rev the engine up in the 8500 rpm range.  With the same boost and increased rpm range, this will now push us up into the 1750-1850 hp range.

Yes, we can go further with more boost, but we started this out talking about a reliable path.   So, that’s what we’re doing here.

Side note or personal opinion:

16. I’d take a 4.1 “cookie cutter” build hands down over a “strengthening only” build for reliability, especially in the 1000hp range.  A 4.1 can produce this at barely over 1.4 bar, with very docile manners and every day drivability.  Where the strengthening only build can get there but will be running 2.2 bar on special fuels and have very limited upgrade capability beyond this point.   A gt3 top end based 4.1 can be even more fun producing that power at barely over a bar of boost, lol.  And while the gt3 top end may be the king of the hill for crazy power numbers and record setting times, you’ll really need to drive the crap out of it to get there with all that rpm.   Maybe I’m just getting old?  Or maybe more maturing in our builds.  Either way, super response, amazing drivability and power under the curve are going to win out for me.   I want an engine built for what I do in the car 99% of the time.  Not a purpose built racing engine that I’ll use 1% of the time and be unhappy the rest of the time.

So, on that note, we’ll leave you with the Path to 1000whp and beyond for Porsche 996 turbo and give you a lot to think about on your journey!

I’m sure there’s plenty more. These are the highlights.  If you think of any more, please tell us in the Comments!  We’d love to make this a great compilation of weak links on the path to 1000whp and beyond!