TD header, tune & afpr question

[Doc Harley]

315hp would be pushing my particular sled to the edge. Stock primary secondary, teenie weenie intercooler. Fleecer, 17 psi vs 20 psi which one will hold up on a lake for a long pull?
IDK?!?!

 

[Fleecer]

Although opinions vary when choosing tunes, I'll share my opinion:

I don't bother switching tunes, as I've learned it's a waste of time and it requires constantly changing the setup.

I would set tune to Max 20 and leave it there. Gear for Max 20, clutch for Max 20, set FPR for Max 20, and when someone pulls up alongside.......the sled will be ready.

If I get stuck with lower octane fuel and want to downgrade to Power trail, I hold it half throttle.......Lol

315hp would be pushing my particular sled to the edge. Stock primary secondary, teenie weenie intercooler. Fleecer, 17 psi vs 20 psi which one will hold up on a lake for a long pull?
IDK?!?!

Max 20 header tune will only make approximately 18.3-18.6# of boost. Header tunes make more power, require slightly less octane, and are safer than stock manifold tunes imo.

Clutches and intercooler can easily take a 1.5 mile pull with quality fuel at 20F. The colder the outside temps, the more it can take. Monitor IATs/belt temps and send it.

Outside temps above 35F I don't make long pulls, as things will exponentially heat up, and I'm afraid the thing catches fire.

 

[Doc Harley]

Max 20 header tune will only make approximately 18.3-18.6# of boost. Header tunes make more power, require slightly less octane, and are safer than stock manifold tunes imo.

Clutches and intercooler can easily take a 1.5 mile pull with quality fuel at 20F. The colder the outside temps, the more it can take. Monitor IATs/belt temps and send it.

Outside temps above 35F I don't make long pulls, as things will exponentially heat up, and I'm afraid the thing catches fire.

Great insight, fleecer. Ty...The last two seasons have been extremely rough around here. Barely been out since I tuned the sled.

 

[Turboflash]

315hp would be pushing my particular sled to the edge. Stock primary secondary, teenie weenie intercooler. Fleecer, 17 psi vs 20 psi which one will hold up on a lake for a long pull?
IDK?!?!

Define "long pull."
A tuned 998, by it's engine design, is thermally limited. Meaning it's ability to shed heat has a maximum capacity (even in the best snow conditions). For example, the heat exchangers in tunnel can only get rid of so much heat. Intercooler had limited ability to cool incoming air from Turbo. But more than that, the cylinder head has a limited ability to get rid of the heat from combustion. There's only so much coolant in head, and there's only a certain amount of aluminum in head that's in contact with coolant. Coolant passages are a limited size.
A stock 998 might be able to withstand several miles at wfo, at the end of which the coolant temp, IAT, and head temps would be way up.
But, a tuned 998 produces a much higher thermal load to the stock cooling system, perhaps double. The cooling system is not big enough to get rid of that much heat (it was never designed to do that). In particular, the cylinder head doesn't have nearly enough coolant going through it to keep head cool at 18+ lbs of boost, to say nothing of 20+ lbs of boost.
The evidence is just watching your coolant temp on your cluster. At wfo, you'll see the coolant temps increasing the longer you're at wfo. Keep in mind, the coolant temp on cluster is what the coolant temp is going into cylinder head (because of where the sensor is), not temp of the coolant exiting the head.
So the answer to how far is wfo ok depends on how close to engine damage do you want to get? Once the head is so hot that the coolant leaving head is boiling. I think that's too much.
I quit when coolant temp starts going past 200-205. Others might push it more. I'm sure the speed guys and racers here will chime in. I pretty much think 3/4 mile wfo is far enough for me most of the time. If I'm racing someone, it's never how fast my top end is compared to his, it's who's ahead at 1000', 1/4 mile, "4 stakes", that kind of thing. Besides, I do think about the chances for track explosion at 135+ mph.
Jm2c

 

[Turboflash]

315hp would be pushing my particular sled to the edge. Stock primary secondary, teenie weenie intercooler. Fleecer, 17 psi vs 20 psi which one will hold up on a lake for a long pull?
IDK?!?!

You can read my response and, if interested, ask me how I know.
Hint, I once made a 5 mile pull wfo! Lol.

 

[Fleecer]

You can read my response and, if interested, ask me how I know.
Hint, I once made a 5 mile pull wfo! Lol.

Great writeup TF......

Opinions will vary here......but I think 5 miles WFO on a tuned winder is a tiny smidge too long. Lol

 

[Slow998]

Looking through my logs, there are multiple 30-40 long second pulls. IMO, everything you need to know is settled long before that! The last 15-20 seconds at WFO is just hoping for another couple MPH.

 

[Doc Harley]

1/4 mile at a time will suffice, for me. Lol. Wis. Is full of tight twisty elevation changes that you never make it past 50 mph. But then the trail spills off into a lake where you can pin it wide Open for a 1/2 mile.
The sled is geared to go 130mph, nothing crazy.
Thanks for the insight, turbo.
Lastly, im setting up to race from the dig. A game where the most HP doesn't always win. Traction & clutching will prevail.

 

[Turboflash]

1/4 mile at a time will suffice, for me. Lol. Wis. Is full of tight twisty elevation changes that you never make it past 50 mph. But then the trail spills off into a lake where you can pin it wide Open for a 1/2 mile.
The sled is geared to go 130mph, nothing crazy.
Thanks for the insight, turbo.
Lastly, im setting up to race from the dig. A game where the most HP doesn't always win. Traction & clutching will prevail.

Amen!

 

[Turboflash]

Looking through my logs, there are multiple 30-40 long second pulls. IMO, everything you need to know is settled long before that! The last 15-20 seconds at WFO is just hoping for another couple MPH.

Totally agree!

 

[Turboflash]

Great writeup TF......

Opinions will vary here......but I think 5 miles WFO on a tuned winder is a tiny smidge too long. Lol

You're absolutely right. Lol.
I was dumb then.
Lesson learned. 3 melted pistons.
All is well now. For extra insurance, my pistons now are gold-coated Swaintech ceramic. Still, 3/4 mile on Stage 4 is far enough. Quit when coolant temp shows 200+. Race is waaaay over by then. Lol

 

[Turboflash]

Looking through my logs, there are multiple 30-40 long second pulls. IMO, everything you need to know is settled long before that! The last 15-20 seconds at WFO is just hoping for another couple MPH.

A multi-mile WFO run might last 2+ minutes. Way too long for a stock cooling system. No stock cooling system can keep the engine at thermostat temp even close to that long.

 

[DMCTurbo]

A multi-mile WFO run might last 2+ minutes. Way too long for a stock cooling system. No stock cooling system can keep the engine at thermostat temp even close to that long.

Multi mile WFO. You guys are nuts.

 

[Turboflash]

Multi mile WFO. You guys are nuts.

You are absolutely correct. 300+ tuned 998 doesn't live at 3-4 miles wfo. Ask me how I know. Fun while it lasted. 3-4 miles at 130 mph. Wheee!

 

[Doc Harley]

As fate would have it, I just finished up my sled and snow is on its way, for my testing grounds. Lol. I'll be able to verify wot AFR & get clutching close as possible. Very exciting. Plus it's nice to be able to take a quick trip around the block and make sure everything's in order. And yes I'll bring my draggy. Just not so concerned about that at this point.
Might be able to sneak a run in up north, between the holidays, pending weather results.