Mod Proposal: Twinscrolling the GT

[Sterling Archer]

Personally I've always thought that if you want to go forced induction, buy the model that offers it. Why buy a 5.0 not setup for forced induction when you know there will be a model that offers it out of the box.

That's just my 2cents though.

Yeah that's a fair point. Price is the main motivator; anything on the market that gives you mustang performance with a turbo costs at least $20k more.

Just curious if you've driven the Audi's you highlight.

I haven't, but I have driven a BMW 335 (with the twin turbos) and I own a VW GTI. Both have relatively well respected turbo engines, and both make great torque down low, but both also have horrible turbo lag.

I drove the 335 at an AutoX, which admittedly is about the worst case situation for exposing turbo lag, and it was not a fun experience due to the lag. I think if I owned the car I'd adapt to the lag for track driving, but for street driving it is very annoying. The GTI is similar. Less power overall but the lag leaves a similar feeling of unresponsiveness.

The only time I really like the feel of the turbo is when going up a hill. That's when you have high, steady state load at a low RPM, and the turbo really works well in that case. When you have dynamic throttle application, the lag is very evident IMO and masks the low-end torque.

So, IMO, turbos look good on a dyno and provide good advertising numbers, but aren't very fun to drive due to the lag.

I think the positive displacement supercharger that's mounted right on top of the engine with the integral intercooler is a much better way to get the low-end torque. The Audi Supercharged V6 is a good example.

Anyhow, if I wanted to get more low end, with quick response, that's the way I'd be looking.

-T

I haven't driven either the rs5 or rs7, I just know their torque curves are flat starting around 1700 rpm or so. Being an engineer sometimes I do let the numbers get the best of me lol.

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[Vee8Thunder]

Hey guys..been lurking a while and this thread made me want to take the plunge and actually make a post

just a few notes from a fellow engineer: 1) the 2015 performance will be comparable to a 302 BOSS, not a 2014 GT. 2) As such, examining the torque curves between the two engines (ie 2013 BOSS vs 2014 GT) reveals that they behave VERY differently at the low end..with the BOSS being much stronger and more in line with the turbo-powered cars mentioned in the thread with a very flat curve overall. Just some food for thought ;)

 

[5.0 Coyote]

Hey guys..been lurking a while and this thread made me want to take the plunge and actually make a post

just a few notes from a fellow engineer: 1) the 2015 performance will be comparable to a 302 BOSS, not a 2014 GT. 2) As such, examining the torque curves between the two engines (ie 2013 BOSS vs 2014 GT) reveals that they behave VERY differently at the low end..with the BOSS being much stronger and more in line with the turbo-powered cars mentioned in the thread with a very flat curve overall. 3) The amount of additional help a turbo can bring to an engine such as the Coyote is limited due to the high compression and lack of direct injection unless you want to run Meth or fill up at the airport the rest of your life. Cost benefit generally isn't there IMHO..you'd be better off (as others have mentioned) in buying a car that was designed with a turbo in mind. Just some food for thought ;)

I don"t know about your engineer,but when FORD listed the specs for there 50th ANV Mustang the HP was listed at 420 HP and that was the 2015 model,so I don"t know where you guys are getting this 450 HP BS.

 

[scottpe]

I haven't driven either the rs5 or rs7, I just know their torque curves are flat starting around 1700 rpm or so. Being an engineer sometimes I do let the numbers get the best of me lol.

As previously mentioned, I think a positive displacement supercharger is your answer. It fattens up the torque down low, much easier to install, no turbo lag and if you buy the ones from Ford Racing, you can have a powertrain warranty along with it (has to be installed by an authorized dealer). Warranties are available with other brands as well, but I can't comment on how the cost compares.

If your application was drag racing, or your goal was maximum power output, I'd say a turbo is probably the best option. But just for something that will increase your stoplight to stoplight fun level on the average daily commute, a positive displacement blower is where it's at.

 

[Grimace427]

Hey guys..been lurking a while and this thread made me want to take the plunge and actually make a post

just a few notes from a fellow engineer: 1) the 2015 performance will be comparable to a 302 BOSS, not a 2014 GT. 2) As such, examining the torque curves between the two engines (ie 2013 BOSS vs 2014 GT) reveals that they behave VERY differently at the low end..with the BOSS being much stronger and more in line with the turbo-powered cars mentioned in the thread with a very flat curve overall. Just some food for thought ;)

I disagree based on the style of intake manifolds between the two engines. The Boss uses a short runner-in-box intake manifold designed to maximise power at the top RPM range whereas both the '11-14 and 2015 Coyote engines utilize a long runner intake manifold designed for low-mid range torque and power. I bet the 2015 Coyote will fit between the two as far as power curves go, and maybe will get close to peak numbers of the previous Boss Roadrunner engine.

 

[Vee8Thunder]

I disagree based on the style of intake manifolds between the two engines. The Boss uses a short runner-in-box intake manifold designed to maximise power at the top RPM range whereas both the '11-14 and 2015 Coyote engines utilize a long runner intake manifold designed for low-mid range torque and power. I bet the 2015 Coyote will fit between the two as far as power curves go, and maybe will get close to peak numbers of the previous Boss Roadrunner engine.

In that case, the 2015 will have even better low-end response, out-performing the BOSS in the low end torque regime while falling a bit short in the top-end power...and be that much better than the 2014 GT. Point being, the shape of the torque curve of the 2014 GT (ie rather anemic feeling until around 3k rpm) is not something that should be expected to be present in the 2015 GT. In either case, my point is still valid that 2014 GT performance perceptions should not be used as a mental benchmark on what mods may/may not be needed for the 2015 GT before one has a chance to drive it.

 

[Grimace427]

In that case, the 2015 will have even better low-end response, out-performing the BOSS in the low end torque regime while falling a bit short in the top-end power.. Point being, the shape of the torque curve of the 2014 GT (ie rather anemic feeling until around 3k rpm).

This is all in Ford's factory tune and not hardware. For all we know Ford will implement the same tuning strategies to the 2015 Mustang. Looking at hardware alone won't give us these kinds of answers.

 

[Vee8Thunder]

This is all in Ford's factory tune and not hardware. For all we know Ford will implement the same tuning strategies to the 2015 Mustang. Looking at hardware alone won't give us these kinds of answers.

I've looked at lots of dyno runs and I've yet to see a custom tune for a 2011-2014 GT that "fixes" it. All of the runs I've looked at have terrible low-end torque below 2500 RPM, and really don't really start coming "alive" until 3k or so. And that's after 4-5 years of people trying to eek all the peformance out of the cars with custom software mods. From all the data I've seen, it is a attribute of that motor...it's just not set up for the low end in the stock hardware configuration. The 2015 will have a Coyote motor which even in a "high HP" configuration as found on the BOSS has dramatically better low-end torque performance per dyno charts. If they fit longer intake runners etc to the 2015 GT version..that will further boost the low-end performance. Yes, they could intentionally cripple it with software (I can't imagine why they would do that after going to the trouble of bolstering the low end via the intake changes, but yeah it IS possible), but at that point a tune WOULD help versus the situation with the 2011-2014 cars.

So again..point is that the 2014 GT is a poor analogy to the expected behavior of the 2015 given all the data presented thus far. *HOW* different is something we'll have to wait for instrumented test drives and/or dyno runs to determine..but I would bet that when it comes down to it the 2015 is going to feel a lot more like a BOSS than a 2014 GT from a torque/power distribution point of view.

 

[scottpe]

The bottom line is, short of increasing displacement, there's only so many tricks that can be employed to broaden the torque curve (substantially increasing the low end) without sacrificing the high end power too much. I believe all of the things that have been discussed will improve the S550 over its predecessors.

The question is whether it will provide a dramatic enough improvement in low-end grunt that I believe the OP is looking for. We can theorize all we want, but the only way to find out will be to wait and drive it. If it still leaves more to be desired, I think a positive displacement blower will be just what the doctor ordered...

 

[w3rkn]

I can relate to what the OP is talking about, but have no idea what is necessary to achieve it on the s550, because as many have mentioned we do not have the proper specs/analysis yet.


I have BMW 135is, (3.0 liter w/scrolling turbo).. & have roughly 350ft-lb of torque just off idle at 1,300 rpms..

I hardly ever see 3,500 rpm during daily driving..

I will be waiting for the first DFI V6 FI Mustang. I have no need for 500hp+, when I can have 400ft-lbs of torque at 2k rpms in a turbo stang.

 

[Sterling Archer]

The bottom line is, short of increasing displacement, there's only so many tricks that can be employed to broaden the torque curve (substantially increasing the low end) without sacrificing the high end power too much. I believe all of the things that have been discussed will improve the S550 over its predecessors.

The question is whether it will provide a dramatic enough improvement in low-end grunt that I believe the OP is looking for. We can theorize all we want, but the only way to find out will be to wait and drive it. If it still leaves more to be desired, I think a positive displacement blower will be just what the doctor ordered...

For this reason I'm seriously considering the ecoboost. I really don't need 450 peak horse power. Just being realistic I'll rarely come close to the redline unless if I take the car to the track - which I do plan on doing, but clearly not as often as city driving.

I can relate to what the OP is talking about, but have no idea what is necessary to achieve it on the s550, because as many have mentioned we do not have the proper specs/analysis yet.


I have BMW 135is, (3.0 liter w/scrolling turbo).. & have roughly 350ft-lb of torque just off idle at 1,300 rpms..

I hardly ever see 3,500 rpm during daily driving..

I will be waiting for the first DFI V6 FI Mustang. I have no need for 500hp+, when I can have 400ft-lbs of torque at 2k rpms in a turbo stang.

Yeah again my main point is that I want low end power for a daily driver. The closer to idle we can get that torque curve, the happier I'll be.

 

[86GT]

Do you guys really not take your car to redline on a semi-regular basis? It's good for the engine to get it up there every once in a while, and on the on-ramps makes for a ton of fun.

 

[jimmypop13]

I can relate to what the OP is talking about, but have no idea what is necessary to achieve it on the s550, because as many have mentioned we do not have the proper specs/analysis yet.


I have BMW 135is, (3.0 liter w/scrolling turbo).. & have roughly 350ft-lb of torque just off idle at 1,300 rpms..

I hardly ever see 3,500 rpm during daily driving..

I will be waiting for the first DFI V6 FI Mustang. I have no need for 500hp+, when I can have 400ft-lbs of torque at 2k rpms in a turbo stang.

I love that feeling. I want a v8 for the sound but I'm torn because nothing beats that low end torque a turbo provides.

 

[jimmypop13]

As previously mentioned, I think a positive displacement supercharger is your answer. It fattens up the torque down low, much easier to install, no turbo lag and if you buy the ones from Ford Racing, you can have a powertrain warranty along with it (has to be installed by an authorized dealer). Warranties are available with other brands as well, but I can't comment on how the cost compares.

If your application was drag racing, or your goal was maximum power output, I'd say a turbo is probably the best option. But just for something that will increase your stoplight to stoplight fun level on the average daily commute, a positive displacement blower is where it's at.

I agree that this will be the best option but man do I love the feeling of a turbo. Problem is you'll probably have to have a turbo setup custom fabricated under the hood with major modifications to the locations of stuff.

 

[Sterling Archer]

Do you guys really not take your car to redline on a semi-regular basis? It's good for the engine to get it up there every once in a while, and on the on-ramps makes for a ton of fun.

I currently drive an automatic escort, couldn't redline if I wanted to

I love that feeling. I want a v8 for the sound but I'm torn because nothing beats that low end torque a turbo provides.

Exactly! I love the sound of the coyote, I just wish it pulled from 1700 rpm instead of 3000.

I agree that this will be the best option but man do I love the feeling of a turbo. Problem is you'll probably have to have a turbo setup custom fabricated under the hood with major modifications to the locations of stuff.

Perhaps, but isn't that the fun part of a mustang? A huge selling point to me is that there exists such a large aftermarket to allow you to do such modifications; it really allows you to inject your own personality into the car.

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