Irace86.2.0's KPower Turbo K24 Swap

[toast]

After I put a supercharger on my car it was intermittent when starting (as in no crank). Very annoying, would leave me in various places. Finally realized I never tightened the 10mm bolt on the battery ground terminal and it was loose...

[Irace86.2.0]

I went back to the dyno today at Sonny's with Shawn from TunedByShawn. The first pull looked really smooth compared to the last pull (here), and the only difference was the new flywheel. (Old vs New):

[Irace86.2.0]

Here are few of the final pulls. This was 9psi. The ID1050x injectors were maxing out, and this is where I wanted to stop anyways (400whp/300wtq). Shawn thought the graph could be smoother, and he thought the injectors could do more, but we were chasing a shifting problem. It seemed like boost was cutting out. Maybe a boost leak, and I had on my list to replace two of the o-rings that seemed smaller than ideal, but after looking at things, he says the problem is the fuel pressure. He says it is dropping, which is common in a returnless fuel system without a boost reference pressure regulator.

I believe the manual says the stock fuel system has a pressure around 51-73psi with a fail safe or something of 58psi. After removing the stock fuel pump controller, the pressure seems to stay at 60psi. Well, it was a good thing I got the fuel pressure sensor because the system was detecting lower fuel pressure and adjusting the duty cycle on the injectors or something like that. He says the pressure was dropping into the 40's or something, so a return, referenced system would be advisable for more power. As you can see from the graphs above, it can be decently smooth, but it seems to be fighting to adjust things when fuel pressure drops. At least, that is what I am understanding.

I'll look into the fueling setup. I know @visbits and others have switched to a return system, but I am not really wanting more power at the moment, and the tune is safe and fine for now, I am told. Overall, I am pretty stoked the car made what it made at only 9psi on a relatively small turbo with plenty of future overhead for more power if I want. Car feels smooth and strong.

[redlined600]

That thing must be a rocket!

[Irace86.2.0]

^^^This.

A 997.2 GT3 is rated at 435hp@7,900rpms with a curb weight around 3,075lbs, and the car dynos around the 400whp/300wtq. The drivetrain losses might be less for the 911 than for a typical RWD car, but I would expect 15-20% and the car to be underrated from Porsche. A 992 GT3 is rated at 503hp@8,400rpms with a curb weight around 3,125lbs, and the car dynos around 450whp/325tq. I don't know what my car weighs, but I think I am looking good from a power-to-weight perspective.

[brzlegend]

You should see 49psi with 9psi oem is 58. If your going below that your fuel pump isnt up to the task.
You can squash the regulator can and get a little more base psi. That's how the factory sets the pressure.
How does it compare to the supercharger?

[Irace86.2.0]

Originally Posted by brzlegend

You should see 49psi with 9psi oem is 58. If your going below that your fuel pump isnt up to the task.
You can squash the regulator can and get a little more base psi. That's how the factory sets the pressure.
How does it compare to the supercharger?

I have the DW300c. I think it should be good with that pump at this power level. I'm not making too much more power than what I was making with the Harrop supercharger at 14.5psi.

The supercharger is more immediate and linear. It feels more NA. The turbo has more torque and is more drama with the surge and noises. Both have their benefits. I would probably prefer the FA24 with a Harrop supercharger because I like immediate throttle response and because this turbo and low boost level doesn't have crazy boost/torque buildup, so there isn't as much drama; might as well have the supercharger without the turbo lag/threshold if the torque curves are identical. With that said, the power is a blast, and I like the 8k redline and setup, so no regrets. It is far more upgradable in power potential if I want to move to the next level.

[brzlegend]

Harrop built 2.1 fa20 on e85 @16psi 364hp and 307 lb ft. You have that beat with 7 psi less boost.

[Irace86.2.0]

Originally Posted by brzlegend

Harrop built 2.1 fa20 on e85 @16psi 364hp and 307 lb ft. You have that beat with 7 psi less boost.

They made more horsepower than that. They didn’t rev it out, which is why they made so much more horsepower when they did rev is out at 19psi for 428hp and 335tq at the hubs. For reference, Kpower made 470whp and 385wtq at 12psi on a K24z3 using the same turbo, but I’m guessing a larger a/r than the .72 that I have on my Pulsar replica, and I doubt they ran a factory cat like me either.

The extra 300cc, 8k rpm redline and the greater efficiency of the turbo are some advantages. The Harrop has that perfectly linear power curve and smooth torque curve and instant throttle response, which is their advantage. They create more cylinder pressure and heat for the same power to the wheels, so a turbo is going to be easier on the engine. Still, the urgency and response from a positive displacement supercharger is a great thing.

[visbits]

RE: Flywheel
Yeah I had ARP bolts cause a problem too, I noticed the change in sound and took it apart before it was too late. I replaced with a steel flywheel and OEM bolts with LT Red.

Originally Posted by Irace86.2.0

Here are few of the final pulls. This was 9psi. The ID1050x injectors were maxing out, and this is where I wanted to stop anyways (400whp/300wtq). Shawn thought the graph could be smoother, and he thought the injectors could do more, but we were chasing a shifting problem. It seemed like boost was cutting out. Maybe a boost leak, and I had on my list to replace two of the o-rings that seemed smaller than ideal, but after looking at things, he says the problem is the fuel pressure. He says it is dropping, which is common in a returnless fuel system without a boost reference pressure regulator.

I believe the manual says the stock fuel system has a pressure around 51-73psi with a fail safe or something of 58psi. After removing the stock fuel pump controller, the pressure seems to stay at 60psi. Well, it was a good thing I got the fuel pressure sensor because the system was detecting lower fuel pressure and adjusting the duty cycle on the injectors or something like that. He says the pressure was dropping into the 40's or something, so a return, referenced system would be advisable for more power. As you can see from the graphs above, it can be decently smooth, but it seems to be fighting to adjust things when fuel pressure drops. At least, that is what I am understanding.

I'll look into the fueling setup. I know @visbits and others have switched to a return system, but I am not really wanting more power at the moment, and the tune is safe and fine for now, I am told. Overall, I am pretty stoked the car made what it made at only 9psi on a relatively small turbo with plenty of future overhead for more power if I want. Car feels smooth and strong.

I setup my car around 91/93 0-Ethanol gas because that's whats available around tail of the dragon.



93 Octane 11:1CR K24A 21Psi. Lot of boost to compensate the lack of any available timing window on this engine. I am going to reduce my CR to 10:1 or 9.5:1 and balance the rotating assembly soon, its the current restriction of making power without meth/etha.


This is a properly calibrated AWD 500 Mustang dyno, you can safely add another 15% on this for a "dynojet" comparison.

[funkjaw]

Any acceleration videos by chance?

[Irace86.2.0]

Originally Posted by funkjaw

Any acceleration videos by chance?

No. Sorry.