Mods vs HP

[MTV7]

I bought my 07 4.6L already modded. It has header back exhaust, ford racing throttle body, CAI, stiffened chassis. That’s what I have found so far.

At any rate, I know the factory horsepower on these is 300 hp. I found a Dyno test done on my car that showed 282 whp and 296 ft/lb torque. I assumed that was a pre-mod Dyno given the numbers.

I hear a lot about supercharged 4.6s topping out at around 400 hp but have heard as much as 600. I have not done a Dyno on my car yet. Obviously a Dyno will tell me real numbers in my car which I intend to do.

But, I am wondering if maybe the Dyno that I know was done at 282 whp is actually post mod? But that doesn’t make sense given factory rating. I would expect post mod to be 330ish. For those who have modded, what has been your experience in pre and post mod hp?

Thanks

 

[Dino Dino Bambino]

I bought my 07 4.6L already modded. It has header back exhaust, ford racing throttle body, CAI, stiffened chassis. That’s what I have found so far.

At any rate, I know the factory horsepower on these is 300 hp. I found a Dyno test done on my car that showed 282 whp and 296 ft/lb torque. I assumed that was a pre-mod Dyno given the numbers.

Your numbers of 282/296 were at the rear wheels. Assuming a typical 12% drivetrain loss for these cars, that's about 320/336 at the crank. That said, the type of dyno you used can make a difference (inertia vs load dyno).

These page show what you can expect on the dyno from various N/A mods:

Mustang 4.6L Three-Valve Dyno Runs

https://www.angelfire.com/my/fan/Mustang2006GT/S197_Bolt_Ons.htm

 

[JC SSP]

Those are good numbers for a basically stock car. Enjoy your ride.

 

[AHaze]

Yeah, 282 wheel HP is likely the "after" number. IIRC, stock '05-'09 GTs put down 270 wheel at best. On a stock engine, the big throttle body will give you basically zero gain and any exhaust that retains the stock manifolds won't do much better.
As for supercharging a 4.6, there's lots of folklore out there on how far you can push it before the stock connecting rods snap and ventilate the block. Some say 450 WHP, others say the torque number is what matters and as long as that stays under 450, you should be OK. Either way, a good tune is vital and there are no guarantees. Some have grenaded at less than 450 WHP, others have been running at 470+ for years and I can think of at least one that made over 500 WHP for long enough to get some time slips.
If you're willing to drop the coin on a built short block, 600 WHP is relatively easy.

 

[Dcraig10004]

That 282/296 is definitely post-mod, and as mentioned above, it depends on what it was dynoed on. Generally, a Powerdyne Mustang Dyno is very stingy giving the numbers you hope for, but they are true numbers compared to other dynos. Throw a set of cams and a FR intake manifold on, and I think you'll be pleased with the results, but keep in mind you need a good tuning guy.

 

[MrBhp]

You just never know what you're going to get on a dyno. My car with nothing but exhaust and cai did 297 on a hot humid day. My tuner at the time felt like it had more in it, but it kept pulling timing back. He figured it was the cats. After long tubes and no cats it did 304. But it felt like a LOT more.
As far as how much hp/tq your specific motor can handle, that's also unknown. The guidelines you here are safe numbers for protecting the weakest components, which as previously stated is usually the connecting rods. I've been running 10lbs of boost with a single turbo setup. Some folks will say that's too much for a daily, but I've put 15,000 miles on it with no issues. And I drive it like a stolen mule. Turbo whp is easier on the engine than a centri or pd. A member on this forum had a built engine ready to go in. He has a single turbo setup on the original engine. Before he put the new long block in, he wanted to find the limits of the factory bottom end. He kept cranking up the boost over period of several weeks. I think he finally windowed the block at 18lbs. I may have that story wrong, but it's probably close enough. I can't remember who the member was.

 

[Dino Dino Bambino]

As far as how much hp/tq your specific motor can handle, that's also unknown. The guidelines you here are safe numbers for protecting the weakest components, which as previously stated is usually the connecting rods. I've been running 10lbs of boost with a single turbo setup. Some folks will say that's too much for a daily, but I've put 15,000 miles on it with no issues. And I drive it like a stolen mule. Turbo whp is easier on the engine than a centri or pd.

I think you've raised a valid point that I hadn't considered until now.
While Brenspeed recommends a 450rwtq ceiling for the stock connecting rods on a forced induction set up, their extensive experience is only on supercharged (positive displacement and centrifugal) 3V engines. Therefore they've never had any turbo engines to collect dyno data from.
I don't know by what mechanism turbos are easier on the engine but I'll make an analysis. What I do know is that the tendency of stock connecting rods to bend or break correlates with cylinder pressure. Unlike a supercharger, a turbo doesn't place any additional load on the front of the crankshaft so it's possible the reduced level of harmonic vibration also reduces the possibility of rod-breaking spikes in cylinder pressure, thereby allowing the rods to tolerate more torque.

 

[GlassTop09]

Turbo whp is easier on the engine than a centri or pd

From a point of science, you're absolutely correct as a turbo doesn't require any force from the crankshaft to operate. Centri's or PD blowers require crankshaft TQ to spin up thus the total engine TQ force output required to make the net engine TQ output you see on a dyno is much higher thus is putting more harmonic stress on the entire rotating assembly than a turbo will at the same rated engine TQ output from a centri or PD blower. The connecting rods are usually the 1st part to fail simply due to design criteria........the last part you want to be failing under these harmonic loads is the crankshaft.......the potential damage area for shrapnel dispersion is a lot greater........less folks will live to tell you about it.

I think you've raised a valid point that I hadn't considered until now.
While Brenspeed recommends a 450rwtq ceiling for the stock connecting rods on a forced induction set up, their extensive experience is only on supercharged (positive displacement and centrifugal) 3V engines. Therefore they've never had any turbo engines to collect dyno data from.
I don't know by what mechanism turbos are easier on the engine but I'll make an analysis. What I do know is that the tendency of stock connecting rods to bend or break correlates with cylinder pressure. Unlike a supercharger, a turbo doesn't place any additional load on the front of the crankshaft so it's possible the reduced level of harmonic vibration also reduces the possibility of rod-breaking spikes in cylinder pressure, thereby allowing the rods to tolerate more torque.

Your analysis is correct. A turbo will not need to output the type of cyl pressures (thus boost pressures) needed to make the same net HP\TQ that is required from a centri (not as bad as a PD blower until you hit the upper top end) or PD blower (by far the hardest on an engine due to its ability to hit max boost pressures at low RPM's). This is what is reducing the harmonic stress loads on the rotating assembly.......also why it's more important to optimize the TQ leveraging thru the crankshaft......you'll need less cyl pressure as well to output the same amount of TQ twisting forces. All this is application of physics where it matters the most.

Far too many folks rely on cyl pressure w\ displacement (old school thinking based off fixed cam in block designs) to make engine HP\TQ but don't think to optimize simple leverage where it exists. This is where VCT comes into play & TQ leveraging works whether NA or FI, whether at low or high RPM's.

Just saying.................

After this, the issue w\ all of these is that some folks don't know (or care to know) when enough is enough according to each blower's design characteristics being used w\ the engine design it's being used on, due to the peer pressure of this sport as someone is always trying to exceed or best another......even when someone is telling them that they've reached a safe limit & beyond this limit all bets are off.

Sometimes this is where whom 1 is listening to may matter more than 1 may realize..............

Simple component manufacturing QA\QC tolerances will dictate within the same engine design that 1 engine may be able to tolerate a little more stress safely than another.

Hope this helps.

 

[JC SSP]

I will add that any forced induction (S/C or Turbo) or power adders (N2o) you are exerting more cylinder pressure and stress on valvetrain and bottom components than a normally aspirated engine. Ford engineers did a good job of developing an engine for performance, mileage and emissions but how much thought went into adding 100-300HP to a stock mass production engine.

Proper fueling, timing (I.e., tuning), driving style etc. will add to longevity but going beyond what is recommended and proven is a recipe for disaster.

Even GT500 have their limitations!

Pick your poison but be wise on how you apply it…

 

[GriffX]

That's an other reason. High pressure on low revs puts more stress on the bearings and connection rods. Turbos kicks in later than a supercharger.

 

[MrBhp]

Turbo is easier on everything pretty much. Two step works well without all the stress associated with a PD. And the Turbo is tunable on the fly with an electronic boost controller. However, the big caveat is the difficulty in passing smog inspection. I still haven't figured it out.

 

[GlassTop09]

I will add that any forced induction (S/C or Turbo) or power adders (N2o) you are exerting more cylinder pressure and stress on valvetrain and bottom components than a normally aspirated engine. Ford engineers did a good job of developing an engine for performance, mileage and emissions but how much thought went into adding 100-300HP to a stock mass production engine.

Proper fueling, timing (I.e., tuning), driving style etc. will add to longevity but going beyond what is recommended and proven is a recipe for disaster.

Even GT500 have their limitations!

Pick your poison but be wise on how you apply it…

Amen to the preacher!