Need Help! Need Advice For Super Charger On 03 Gt

[Three50won]

I personally think you're either a centri guy or a PD guy. Well, the turbo guys are actually better than centri and PDs, lol! I personally prefer centris. But you won't catch me saying a PD blower sucks and isn't fun to have. Point is, if fun is the ultimate goal, then either one will more than fulfill your desires. If you're racing to win, then you have to look at your entire set-up and run forced induction that will optimize your set-up.

 

[Gearbanger 101]

I personally think you're either a centri guy or a PD guy.

Not at all. It pretty much depends on the application for me.

Regarding the 4.6L mod motors, they all suffer from the same issue....an issue which cannot be denied. They're all soft on the bottom end....all of them.....period. They don't have the displacement capacity, or the bore size to remedy this condition on their own. Even stroked and bored (which is an expensive venture on with a modular engine), the potential for a significant displacement increase is limited....and so too is N/A torque and horsepower capability. That being the case, ONLY a positive displacement blower can address that issue by artificially increasing displacement just off idle. In my experience, PD blower car's don't feel like power adder cars....they feel like big engine cars. While centrifugals also increase horsepower and torque figures dramatically, they do so far later in the power band and IMO don't attack the problem at it's weakest point.

Top end horsepower and torque figures seem to be comparable for both....but low end figures are not. THIS is why in the modular world, the PD blowers get the nod from me!

.....on the other hand, most 5.0L OHV engines don't suffer the small chamber, small bore, tight valve spacing that the modular engines do. Thus, tend to make good torque and horsepower lower in the RPM range, (despite having a shorter stroke).

Furthermore, displacement can be increased dramatically....beyond 50ci with a production windsor block, with relatively little expense (in comparison to the cost of a modular stroker assembly). Because of this, centrifugal blowers can be used without such pronounced negative effects in the lower regions of the power band. Couple that with the fact that since OHV engines don't have the unused real estate within their intake galley to accept an intercooler brick like the modulars do nobody offers any off the shelf intercooled PD kit for the OHV engines, which makes centrifugal blowers the obvious choice for owners wanting to make big, bolt on power.

So no....I wouldn't say I'm bias towards one, or the other. It boils down to using the "best tool for the job" for me. I'd have a V3 bolted to the front of my car in the blink of an eye if finances allowed it....but alas, Nitrous seems to be the best back for the buck option for me right now.

 

[Deleted member 38176]

Not at all. It pretty much depends on the application for me.

Regarding the 4.6L mod motors, they all suffer from the same issue....an issue which cannot be denied. They're all soft on the bottom end....all of them.....period. They don't have the displacement capacity, or the bore size to remedy this condition on their own. Even stroked and bored (which is an expensive venture on with a modular engine), the potential for a significant displacement increase is limited....and so too is N/A torque and horsepower capability. That being the case, ONLY a positive displacement blower can address that issue by artificially increasing displacement just off idle. In my experience, PD blower car's don't feel like power adder cars....they feel like big engine cars. While centrifugals also increase horsepower and torque figures dramatically, they do so far later in the power band and IMO don't attack the problem at it's weakest point.

Top end horsepower and torque figures seem to be comparable for both....but low end figures are not. THIS is why in the modular world, the PD blowers get the nod from me!

.....on the other hand, most 5.0L OHV engines don't suffer the small chamber, small bore, tight valve spacing that the modular engines do. Thus, tend to make good torque and horsepower lower in the RPM range, (despite having a shorter stroke).

Furthermore, displacement can be increased dramatically....beyond 50ci with a production windsor block, with relatively little expense (in comparison to the cost of a modular stroker assembly). Because of this, centrifugal blowers can be used without such pronounced negative effects in the lower regions of the power band. Couple that with the fact that since OHV engines don't have the unused real estate within their intake galley to accept an intercooler brick like the modulars do nobody offers any off the shelf intercooled PD kit for the OHV engines, which makes centrifugal blowers the obvious choice for owners wanting to make big, bolt on power.

So no....I wouldn't say I'm bias towards one, or the other. It boils down to using the "best tool for the job" for me. I'd have a V3 bolted to the front of my car in the blink of an eye if finances allowed it....but alas, Nitrous seems to be the best back for the buck option for me right now.

Just wastegate and gear a centri....bingo, low-end fixed.

 

[Gearbanger 101]

Just wastegate and gear a centri....bingo, low-end fixed.

Ahhh, if it were only that easy. A waste-gate won't make the blower spin faster to create the CFM require to supply the needed airflow in the bottom end. You need to pulley it for that....and now you're creating another problems. A pullied centrifugal blower that uses a waste-gate to control peak manifold pressure in order to increase airflow down low is also now starting to spin out of it's adiabatic efficiency range, manufacturing excess heat and flattening out the air charge up top.....which has you running into the same issue you chastised the Positive Displacement blowers for having. That is assuming of course you manage to control the belt slip you've now created, with the minuscule pulley size you're going need to get close to matching the PD's low end airflow capabilities.

Adding gears will get you into that power band faster for certain, but now you're back to affecting fuel mileage and drivability. Give and take.

Know what does a better job of picking up the bottom end, without making compromises to the cars drivability or mileage....installing the correct blower in the first place.

 

[Deleted member 38176]

Ahhh, if it were only that easy. A waste-gate won't make the blower spin faster to create the CFM require to supply the needed airflow in the bottom end. You need to pulley it for that....and now you're creating another problems. A pullied centrifugal blower that uses a waste-gate to control peak manifold pressure in order to increase airflow down low is also now starting to spin out of it's adiabatic efficiency range, creating excess heat and flattening out the air charge up top.....which has you running into the same issue you chastised the Positive Displacement blowers for having. That is assuming of course you manage to control the belt slip you've now created, with the minuscule pulley size you're going need to get close to matching the PD's low end airflow capabilities.

Adding gears will get you into that power band faster for certain, but now you're back to affecting fuel mileage and drivability. Give and take.

Know what does a better job of picking up the bottom end, without making compromises to the cars drivability or mileage....installing the correct blower in the first place.

Jesus Christ dude, there is no arguing with you. Your arguments are purely "what if" and not fact. Now we're discussing fuel mileage and drivability.....as if the instant torque of a PD doesn't affect drivability (I'd insert an eyerolling emoticon here if SNs emoticons fkn worked)

Will one of you PD nut-swingers please provide CONCRETE proof that PD's are superior to centri's (such as vids). Dyno graphs are BS. Theres a reason why PD blowers get there asses handed to them from what Ive seen at my track.

 

[Gearbanger 101]

Jesus Christ dude, there is no arguing with you. Your arguments are purely "what if" and not fact. Now we're discussing fuel mileage and drivability.....as if the instant torque of a PD doesn't affect drivability (I'd insert an eyerolling emoticon here if SNs emoticons fkn worked)

Will one of you PD nut-swingers please provide CONCRETE proof that PD's are superior to centri's (such as vids). Dyno graphs are BS. Theres a reason why PD blowers get there asses handed to them from what Ive seen at my track.

lol.....don't get your panties in a wad slick. You're the one who's barking out opinions like they're gospel. You go ahead and disprove any of the FACTS I plainly stated above as false and I'll concede. It's not "what if's" its thermodynamics. The harder you spin a blower, the more heat it makes. Depending on the adiabatic efficiency rating of said particular blower, the faster, or slower you spin it will determine how above or below its efficiency range it becomes. You suggesting to over-spin a centrifugal to match the low end characteristics of a PD blower is outright silly. A Centrifugal hasn't got a prayer no matter how fast you spin it of matching the airflow output of a similarly class PD blower and either A) keeping a belt on its pulley, B) staying within it's rated efficiency range or C) holding together.

One of the advantages previously mentioned earlier PD blower had was their ability promote excellent acceleration without a penalty to drivability, or fuel mileage. You're now suggesting to add that penalty back into the equation by swapping out rear gears to make up for the Centrifugals short comings in the lower regions. Like I said....give and take. Don't like it? Don't care....that's just the way it is!

I'm going to assume you know what a bypass valve is....so I'll pretend you just misspoke when you started barking a PD blower affecting mileage or drivability. Of course when you get on it, additional fuel is going to be added in relation to the amount of additional airflow you're making....but that doesn't mean you're running around under boost all of the time. The car performs as well as stock (even better at times) when driving around normally.....and comes to life with a flick of the right foot....and it does so without the need to increase the final rear end ratio.

You're were right regarding it's affecting drivability. It's actually IMPROVED!!! Like I said earlier. PD car's don't feel like power adder cars. They feel like big engine cars. The power delivery is smooth and immediate, as though you've just yanked your 281 out in favour of a big block FE. There's no lack lustre pull down low with a "make up for lost time" top end pull like there is with a centrifugal, or lag down low with a sledge hammer hit like there is with a turbo. Just smooth, linear power that keeps climbing till red line.

You're just under the mistaken impression that the centrifugals pull so much more power up top than PD's do, because they've got so much to make up for down low. The numbers as Will stated earlier end up for the most part relatively the same by the top end. Your butt will lie to you, the dyno won't!

I even went as far as stated I had an unbiased opinion towards both set ups and gave examples of what one I liked better for each application and you're still butt hurt that I won't completely turn my back on a PD blower in favour of a Centi. There's certainly a blower specific nut hugger in this thread, but you're not going to see him unless you stand in front of a mirror. You're presented with facts and logic, but all you hear are opinions and absurdities. Just can't let it go, can ya? When you find yourself in a hole my friend, it's generally best to stop digging.

As for video's....I dunno....what would you like to see? There are hundreds of them out there. Both showing wins on both sides....so I'm really not sure what it's supposed to prove. A particular blower isn't going to make up for a host of other mods someone else has, poor track conditions or a bad driver, but it video's are what you want.....

Found this one you might not like. I'll give you a hint....the Kenne Bell car is white.


View: http://youtu.be/JsiGgGAcFgI


Found a couple of others showing some mid/top end pulls where the Centrifugals are supposed to rule the roost, but that's not how it went. It's too bad all these big top end runs are street racing video's that violate SN's Terms of Service, huh?

If you really want to see it though, just search Youtube under "Kenne Bell 1.7 2003 Mustang GT vs Vortech 1999 GT" and you'll find it.

 

[Mattstang04]

Gentleman...

 

[Three50won]

Gearbanger, I'm not gonna even get into another long and drawn out discussion about this with you because I have seen the exact opposite of what you're talking about. We aren't gonna agree on this. Despite what you say, and despite all the technical info about centris and PDs, I've seen PDs loose their breath and fall flat on their face when centri blowers were just getting into their stride. And despite what you say, my centri powered GT accelerated hard even when it wasn't in boost. And it didn't take much to get her into boost. Maybe full boost took a little longer, but that thing shot up to 10-12 pounds almost instantly. And even out of boost you're still force feeding the engine. So it will accelerate quicker. Regardless, we aren't going to agree. So let it rest man. Or if you want, and if you're soo confident, we can put your theory to the test once my GT is built and blown...because for all you say, I'm confident a similarly built car with a PD blower will be a neck and neck race with me coming out on top.

 

[Three50won]

And posting one video proves absolutely nothing. Posting 100 videos proves nothing.

 

[Gearbanger 101]

Gearbanger, I'm not gonna even get into another long and drawn out discussion about this with you because I have seen the exact opposite of what you're talking about. We aren't gonna agree on this. Despite what you say, and despite all the technical info about centris and PDs, I've seen PDs loose their breath and fall flat on their face when centri blowers were just getting into their stride. And despite what you say, my centri powered GT accelerated hard even when it wasn't in boost. And it didn't take much to get her into boost. Maybe full boost took a little longer, but that thing shot up to 10-12 pounds almost instantly. And even out of boost you're still force feeding the engine. So it will accelerate quicker. Regardless, we aren't going to agree. So let it rest man. Or if you want, and if you're soo confident, we can put your theory to the test once my GT is built and blown...because for all you say, I'm confident a similarly built car with a PD blower will be a neck and neck race with me coming out on top.

You say you aren't going to get into another long and drawn out discussion about this, yet here you are....at it again?! For the record, it wasn't my intent to get into a long drawn out discussion with anyone either. I didn't get back into this one again until I was goaded into it by one of your brethren, so if you want to blame someone for this fiasco.....

Since the can of worms is open for another serving, I'll say it again, THE SEAT OF THE PANTS FEELING LIES....THE DYNO DOESN'T! For the most part, if the the two set ups are equally sized, they end up fairly close to one and other at their horsepower peak. The "completely running out of breath" statement. is for lack of any better description....False. Tim from the old MPH sold and tuned literally hundreds of both Vortech and Kenne Bell "mongoose" kits at his shop over the years. Both when spun to the tune of 8-9psi peaked out at about the same 370-400 horsepower. As the matter of fact, more often than not the Kenne Bell made a little more up top....and this was back when they were still using the old 1.7L Autorotor compressor. Regardless....even though they both ended on approximately the same high note, only the Positive Displacement supercharger picked up horsepower and torque in the lower regions. The Vortech, did not. Undeniable advantage to the Kenne Bell! All the proof you need is there, you need only to open your eyes to see it.

Regarding your car.....Mods? Blower? Boost? Track times? Trap Speed? Would love to know what kind of blower you're running and how fast you've got it spinning to see 10-12psi "almost instantly". Surely you must have a dyno graph to back your claim? Something tells me that you and I have a very different definition of the word "instant"?

And I'm not sure how you figure the car is making any additional power over stock under vacuum? That's the whole point of forced induction in the first place. Boost is a measure of restriction taking place in the intake track when the system is pressurized. Without it, the blower is simply free wheeling.....actually to some small degree even costing additional power, since the engine is now driving another accessory. Or are you under the impression that all those centrifugal dyno graphs that don't start their power curve until 3,000RPM and above mark are that way because the dyno won't register any lower than that?

Forest through the tree's man.

And posting one video proves absolutely nothing. Posting 100 videos proves nothing.

Lol....I'm pretty sure that's exactly what I stated. Of course, I'm not the one insisting on posting video's to illustrate my point. You have your buddy Nightfire to thank for that one.

 

[restomod66]

Is there an emoticon for a pissing contest? Facts seem to have gone by the wayside and have been replaced with, "This is what I see at my local track". What you see at your local track (wherever that may be) is going to be completely different than what others see at their own track therefore making it a ludicrous tool for debate. Some people cannot be argued with or reasoned with despite having empirical data (dyno graphs) crammed down their throat. Entertaining it has been to read however.

 

[jetmech807]

Could make one, but a couple of smiley's pi$$ing on each other might give a whole different feel than was intended.

 

[sneaky98gt]

...I've seen PDs loose their breath and fall flat on their face when centri blowers were just getting into their stride...

"Fall on their face"? WTF are you smoking?

You mean kinda like this stock 2013 GT500 with a little-bitty 2.3 TVS? Yea, falling on it's face making peak horsepower at 7000 rpm.

Or maybe this 07 GT500? With the power still climbing at 6300 rpm with a Kenne Bell AND the Eaton?

Or maybe the countless 03/04 Cobras that make power to over 6500 rpm on a stock blower?

Heck, even my car with a non-intercooled M112 on 2-valve heads made peak power at over 6200 rpm, and only fell off about 20 horsepower up to 6500 rpm (where we stopped the pull). This whole "running out of breath" is a complete myth, or more accurately, an outright lie. You can argue about dyno numbers all day long (and if you knew me well, you'd know that I HATE dyno racing), but you can't simply ignore one car making TWICE (or sometimes even more) the power of another car across a significant amount of the powerband.

Just because your centrifugal blower pulls harder up top in the rpm range than it does in the lower rpm range (i.e. "pulls like a freight train up top", or "it never feels like it'll stop pulling on the highway") doesn't mean that it pulls harder up top than a positive displacement blower does. Has it ever crossed your mind that a positive displacement blower pulls just as hard up top, except it also pulls better down low? I hate to break it to you, but in the vast majority of street car cases (where we don't have a motor set up to only make power from 5000-8000 rpm), that is EXACTLY the case.

Is there an emoticon for a ****ing contest? Facts seem to have gone by the wayside and have been replaced with, "This is what I see at my local track". What you see at your local track (wherever that may be) is going to be completely different than what others see at their own track therefore making it a ludicrous tool for debate. Some people cannot be argued with or reasoned with despite having empirical data (dyno graphs) crammed down their throat. Entertaining it has been to read however.

I hope I made it clear earlier that I'm trolling a little bit.....but at the same time, I'm not. I hear some of these pro-centri arguments, and how they can sometimes be mis-represented a little bit, and would like to clear it up for anyone reading in the future (or now) who may not know any better.

Also, the 'seeing things at local track'. I agree with your main point, but a discrepancy in track experience (and car experience in general) should be taken into account. I don't know about these other guys, maybe their John Force's sons for all I know. But I've been racing for the better part of a decade now, with upwards of 1000 passes on my car. I've seen a lot of REAL racing at the track, with REAL setups, REAL drivers, REAL errors made, and REAL defficiencies in a given platform. You've really got to look out for the 'internet warrior' who pays someone else to build them a dyno queen, without having any serious track, racing, or wrench-turning experience. I'm not suggesting anyone here fits that profile, but I see that profile of person A LOT online, and they almost invariably give bad performance advice online. It's these people, combined with my personal experience, that'll I'll argue with folks online about things like centri vs. PD, 3.73s vs. 4.10s, modded suspension or not, etc.

 

[Three50won]

You say you aren't going to get into another long and drawn out discussion about this, yet here you are....at it again?! For the record, it wasn't my intent to get into a long drawn out discussion with anyone either. I didn't get back into this one again until I was goaded into it by one of your brethren, so if you want to blame someone for this fiasco.....

Since the can of worms is open for another serving, I'll say it again, THE SEAT OF THE PANTS FEELING LIES....THE DYNO DOESN'T! For the most part, if the the two set ups are equally sized, they end up fairly close to one and other at their horsepower peak. The "completely running out of breath" statement. is for lack of any better description....False. Tim from the old MPH sold and tuned literally hundreds of both Vortech and Kenne Bell "mongoose" kits at his shop over the years. Both when spun to the tune of 8-9psi peaked out at about the same 370-400 horsepower. As the matter of fact, more often than not the Kenne Bell made a little more up top....and this was back when they were still using the old 1.7L Autorotor compressor. Regardless....even though they both ended on approximately the same high note, only the Positive Displacement supercharger picked up horsepower and torque in the lower regions. The Vortech, did not. Undeniable advantage to the Kenne Bell! All the proof you need is there, you need only to open your eyes to see it.

Regarding your car.....Mods? Blower? Boost? Track times? Trap Speed? Would love to know what kind of blower you're running and how fast you've got it spinning to see 10-12psi "almost instantly". Surely you must have a dyno graph to back your claim? Something tells me that you and I have a very different definition of the word "instant"?

And I'm not sure how you figure the car is making any additional power over stock under vacuum? That's the whole point of forced induction in the first place. Boost is a measure of restriction taking place in the intake track when the system is pressurized. Without it, the blower is simply free wheeling.....actually to some small degree even costing additional power, since the engine is now driving another accessory. Or are you under the impression that all those centrifugal dyno graphs that don't start their power curve until 3,000RPM and above mark are that way because the dyno won't register any lower than that?

Forest through the tree's man.



Lol....I'm pretty sure that's exactly what I stated. Of course, I'm not the one insisting on posting video's to illustrate my point. You have your buddy Nightfire to thank for that one.

For the record Gear, I came on this post trying to be neutral. You quoted me and started with your whole PDs are the best thing ever spiel. My comments at first were just politely stating that some people like PDs and others like centris...which is absolutely 100% true regardless of whichever whomever thinks is better. But you just had to start drilling about it. So yes, I said I'm not getting into a long drawn out argument again over this. Because WE ARE NOT GONNA AGREE. And I don't care to keep arguing with you about it. Note I'm not arguing about it now, I'm just saying let it go. I don't care what proof or technical data you think you have. Because for everything you post to confirm your beliefs, I can post the exact opposite to cement my beliefs. So like I said, let it go. You prefer PDs, I respect that. I'm a centri guy. You think PDs are better. Ok fine. Good. Case closed. Lets move on.

 

[Three50won]

"Fall on their face"? WTF are you smoking?

You mean kinda like this stock 2013 GT500 with a little-bitty 2.3 TVS? Yea, falling on it's face making peak horsepower at 7000 rpm.

Or maybe this 07 GT500? With the power still climbing at 6300 rpm with a Kenne Bell AND the Eaton?

Or maybe the countless 03/04 Cobras that make power to over 6500 rpm on a stock blower?

Heck, even my car with a non-intercooled M112 on 2-valve heads made peak power at over 6200 rpm, and only fell off about 20 horsepower up to 6500 rpm (where we stopped the pull). This whole "running out of breath" is a complete myth, or more accurately, an outright lie. You can argue about dyno numbers all day long (and if you knew me well, you'd know that I HATE dyno racing), but you can't simply ignore one car making TWICE (or sometimes even more) the power of another car across a significant amount of the powerband.

Just because your centrifugal blower pulls harder up top in the rpm range than it does in the lower rpm range (i.e. "pulls like a freight train up top", or "it never feels like it'll stop pulling on the highway") doesn't mean that it pulls harder up top than a positive displacement blower does. Has it ever crossed your mind that a positive displacement blower pulls just as hard up top, except it also pulls better down low? I hate to break it to you, but in the vast majority of street car cases (where we don't have a motor set up to only make power from 5000-8000 rpm), that is EXACTLY the case.



I hope I made it clear earlier that I'm trolling a little bit.....but at the same time, I'm not. I hear some of these pro-centri arguments, and how they can sometimes be mis-represented a little bit, and would like to clear it up for anyone reading in the future (or now) who may not know any better.

Also, the 'seeing things at local track'. I agree with your main point, but a discrepancy in track experience (and car experience in general) should be taken into account. I don't know about these other guys, maybe their John Force's sons for all I know. But I've been racing for the better part of a decade now, with upwards of 1000 passes on my car. I've seen a lot of REAL racing at the track, with REAL setups, REAL drivers, REAL errors made, and REAL defficiencies in a given platform. You've really got to look out for the 'internet warrior' who pays someone else to build them a dyno queen, without having any serious track, racing, or wrench-turning experience. I'm not suggesting anyone here fits that profile, but I see that profile of person A LOT online, and they almost invariably give bad performance advice online. It's these people, combined with my personal experience, that'll I'll argue with folks online about things like centri vs. PD, 3.73s vs. 4.10s, modded suspension or not, etc.

Well you have your opinion and I have mine...suffice to say. You have your info that tells you what you know, I have mine. Your info tells you PDs are better. Mine tells me centris are better. We are not gonna agree on this. We'll agree on other stuff. And we'll disagree on other stuff also. But we aren't gonna agree even slightly on this one. Let it go.

 

[Gearbanger 101]

 

[jetmech807]

Any particular reason why you prefer a KB over a centri or turbo setup? Positive displacement blowers (like the KB) are tons of fun on the street (where speeds are usually rather low). A properly set-up centri or turbo will outrun a positive displacement blower 9 times out of 10 in a true race (max RPM). Also, PD blowers like the KB suffer from "heat soak" which hurts both performance and the motor. Centri and turbo setups avoid this by utilizing an air-to-air intercooler which significantly reduces the temp of the air entering the engine.

I say you look into Procharger or Vortech/Paxton

Everybody giving GB crap for arguing and starting crap might want to re read who typed what. This is post #2 telling us how 9 times out of 10 Pd just can't hang. Guess nobody was allawoed to state anything to the contrary of that? Maybe some of us might not agree with your opinion's on the this subject. A few of us may have seen things completely different.

 

[Three50won]

Everybody giving GB crap for arguing and starting crap might want to re read who typed what. This is post #2 telling us how 9 times out of 10 Pd just can't hang. Guess nobody was allawoed to state anything to the contrary of that? Maybe some of us might not agree with your opinion's on the this subject. A few of us may have seen things completely different.

You're kinda blowing what he said outta proportion. Read the entire comment. He said a "properly set-up centri or turbo...in a true race (max RPM)". Even GB agreed to some extent that a centri will make more (even if its only a little bit more as he suggested) power up top or at higher RPMs. And NF never said "can't hang" BTW...he said the centri will "outrun". Big difference between getting outran and not being able to hang. Just sayin...you kinda made those statements out to be a harsh criticism when it seemed to be just an objective comment.

 

[Gearbanger 101]

lol....curious....I wonder what constitutes a "properly set-up centri or turbo"? And is that in comparison to an "unproperly set up" Positive Displacement car?

There doesn't seem to be any winning with some people.? Will and I have both provided hard facts and data to illustrate out points, but they're being dismissed by the opposition as unfounded opinion because they've seen the odd PD car get beat at their local track and automatically assume it has everything to do with the blower.

Meanwhile their side of the argument has provided nothing but replies that start with "At my track I....", with zero data, or hard numbers to back what they just "know deep down" to be right, regardless of the evidence presented that supports the contrary....yet we're being the unreasonable ones?

 

[jetmech807]

I suppose. Was writing that with a concussion from following the back and forth.