would the GT intake work better on a BOSS engine? lets find out!

[isrboss]

With some spec classes (like NASA American Iron) they mandate a hp/weight and hp/torque ratio - maximum. So it becomes a racers dilemma if they want to trade high end speed (say < 10mph on at most two long straights but typically just one) for mid range torque (acceleration they can use throughout the track) and many do. I suppose for other applications like drag or autocross the calculus for which intake to run may change.

And of course most dyno addicts only care about HP numbers...so there's them. ;-)

Also, its important to understand (not you but in general) that putting the GT intake on does not "add power" but rather releases it. It's already there. Kinda the same thing with the CJ intake, but I won't go there. There's a flame thread about that elsewhere. :burn:

That makes sense darreng, thanks for clearing up the rules some. Now are these cars Boss' or GT's to begin with, and are the rules different as far as rev limit for the boss and GT?

As far as the power is already there, of course it is. As with any combustion engine, make it more efficient and it performs better(in a certain range).

 

[pufferfish]

There's no limit on rpm or components, but they tune right to the maximum power they can run and flatline to redline, which would negate the extra high rpm power possible with the boss intake. So, if you can't have high rpm power, the gt's midrange is desirable.

I believe they actually are limited by much more than my graph shows for the gt intake. So, their curve probably goes up to about 380hp and just sits level all the way to redline. Must be weird feeling.

By the way, I have been driving around with the boss intake since leaving the tuner yesterday and I really do like how linear the power is. 8000rpm power shifts are THRILLING! I just don't know that I could see myself realistically shifting at 8 grand 10-15 times per lap. It's very unnerving! But if I don't shift that high every time, the numbers work better for the gt intake (on paper at least).

 

[Voltwings]

Having previously owned a turbo 4 cylinder on E85 (Mazdaspeed 3, dynoed 330 whp / 420 wtq on stock turbo 480 whp / 390 wtq on a gtx3576) i can hands down say Torque > Horsepower.

It takes much less torque to jump someone off the hit than it does horsepower to play catch up. Obviously I'm talking slightly apples to oranges here, but i think the principle remains the same: Theres no sense in turning a coyote into a honda, where its only useful being rung to the ragid edge, the point of a V8 is to have torque ...

 

[86Fbody]

As fun as the Boss intake may be, it's starting to make sense to have the GT intake since the Mustang isn't entirely a momentum car like a Miata.

 

[CFRMSVT]

That's what Procharger F1's are for

 

[isrboss]

Having previously owned a turbo 4 cylinder on E85 (Mazdaspeed 3, dynoed 330 whp / 420 wtq on stock turbo 480 whp / 390 wtq on a gtx3576) i can hands down say Torque > Horsepower.

It takes much less torque to jump someone off the hit than it does horsepower to play catch up. Obviously I'm talking slightly apples to oranges here, but i think the principle remains the same: Theres no sense in turning a coyote into a honda, where its only useful being rung to the ragid edge, the point of a V8 is to have torque ...

I think we all know what the benefits of tq vs hp is. Saying "I made 420ft/lbs of torque" in itself is open ended, was it peaky or flat and usable. I don't go from a hit, on a road course you should already be carrying momentum. Given a nice straight I think we all can assume a high hp motor is going to make up for a hit. Best example I can think of is at Sebring, I met a great guy with a 2003 Cobra putting high 400's hp to the ground, and I'm sure the tq was right there as well. He was doing track days longer than me(both of us solo), and was telling me some cool on track stories of the past. We were both on street tires, and all I had done to the Boss was TK and K&N drop in with coilovers. I had no problems going by him making less tq and hp. He was trying hard to stay with me and that tq bit him coming out of the hairpin and he spun. He also asked me what the Boss had that made it so fast down the straights. There were multiple Boss and 11+ GT's out there, and he said the Boss' drove by him so easy. After I told him the Boss has 3.73's he felt that was making a huge difference. The thing I noticed more than anything while passing high HP/Tq mustangs was I was on the gas, when they weren't. So far the tracks I have been to in FL. all seem to have decent straights, so the high rpm power is nice. At Homestead I seem to have good midrange tq, when exiting turn 8 I just stay in 3rd and I usually seem to exit here better than a lot on track. Coming into 10 I'm usually lifting so I'm not pushing cars in to a mistake. I'm not saying the Boss intake is better than the GT, I understand what ever advantage can be gained in competition use it. I'm not ever going to race my Boss , but I do enjoy going for a good lap time.

The real story always lays with the driver. .

 

[EJR]

Ill stick with my boss intake....actually...no i wont.....



.....cobra jet

 

[pufferfish]

From all I've seen, the CJ is the "have your cake and eat it too" kind of wonderful! I would go for it, but I would break out of my HP range for TT3 and have to compete against the sequential shifted big boys turning 10 seconds per lap better that my lap times.

 

[Voltwings]

I think we all know what the benefits of tq vs hp is. Saying "I made 420ft/lbs of torque" in itself is open ended, was it peaky or flat and usable. I don't go from a hit, on a road course you should already be carrying momentum. Given a nice straight I think we all can assume a high hp motor is going to make up for a hit. Best example I can think of is at Sebring, I met a great guy with a 2003 Cobra putting high 400's hp to the ground, and I'm sure the tq was right there as well. He was doing track days longer than me(both of us solo), and was telling me some cool on track stories of the past. We were both on street tires, and all I had done to the Boss was TK and K&N drop in with coilovers. I had no problems going by him making less tq and hp. He was trying hard to stay with me and that tq bit him coming out of the hairpin and he spun. He also asked me what the Boss had that made it so fast down the straights. There were multiple Boss and 11+ GT's out there, and he said the Boss' drove by him so easy. After I told him the Boss has 3.73's he felt that was making a huge difference. The thing I noticed more than anything while passing high HP/Tq mustangs was I was on the gas, when they weren't. So far the tracks I have been to in FL. all seem to have decent straights, so the high rpm power is nice. At Homestead I seem to have good midrange tq, when exiting turn 8 I just stay in 3rd and I usually seem to exit here better than a lot on track. Coming into 10 I'm usually lifting so I'm not pushing cars in to a mistake. I'm not saying the Boss intake is better than the GT, I understand what ever advantage can be gained in competition use it. I'm not ever going to race my Boss , but I do enjoy going for a good lap time.

The real story always lays with the driver. .

I can see we are coming at this from two different angles so i suppose we'll have to agree to disagree: On a track theres no denying the benefits of a high revving / hp motor; but on the street, when Joe blow rolls up and gives you the nod ... its nice having some torque under you haha. I suppose these CJ intakes will become more popular here in the near future for that reason.

 

[BMR Tech]

RPM is king, but you have to set the car up to work with it. If you actually compare the force to the tires....a steeper geared car with a higher/peaky power curve, will apply more force to the tire than a lower (numerically) geared car, with a so-called "broad" power curve.

A good example would be, a car that loses 20 ft lbs at 4000 RPM, with a gear change, can actually apply more force (think power) to the tires, than the more powerful combo that makes 20ft lbs more, with a lower numeric gear ratio. If you do the math, you will see what I mean.

It all boils down to what the person wants. Me, I prefer a higher curve - which also results in a flatter/higher TQ output. In a heads up drag-race class, assuming the cars launch similar - the car with more RPM through the traps is typically the winner.

On a road course...the higher geared / higher revving combo can make the same power to the tires (effective power - force) coming out of a corner....then run away on the straight. That is how a Boss was engineered.

As for the Boss intake, I don't think it is better specifically on the Boss Engine, I think it is better on a GT engine as well, assuming the tuning and gearing is proper.

 

[Ultrakla$$ic]

That's what Procharger F1's are for

THIS!!!!!:rockon:

 

[Deranged2013]

Guess I'll be ditching the Boss manifold for a CJ IM. The Boss IM will make a nice garage ornament.

 

[86Fbody]

I think we all know what the benefits of tq vs hp is. Saying "I made 420ft/lbs of torque" in itself is open ended, was it peaky or flat and usable. I don't go from a hit, on a road course you should already be carrying momentum. Given a nice straight I think we all can assume a high hp motor is going to make up for a hit. Best example I can think of is at Sebring, I met a great guy with a 2003 Cobra putting high 400's hp to the ground, and I'm sure the tq was right there as well. He was doing track days longer than me(both of us solo), and was telling me some cool on track stories of the past. We were both on street tires, and all I had done to the Boss was TK and K&N drop in with coilovers. I had no problems going by him making less tq and hp. He was trying hard to stay with me and that tq bit him coming out of the hairpin and he spun. He also asked me what the Boss had that made it so fast down the straights. There were multiple Boss and 11+ GT's out there, and he said the Boss' drove by him so easy. After I told him the Boss has 3.73's he felt that was making a huge difference. The thing I noticed more than anything while passing high HP/Tq mustangs was I was on the gas, when they weren't. So far the tracks I have been to in FL. all seem to have decent straights, so the high rpm power is nice. At Homestead I seem to have good midrange tq, when exiting turn 8 I just stay in 3rd and I usually seem to exit here better than a lot on track. Coming into 10 I'm usually lifting so I'm not pushing cars in to a mistake. I'm not saying the Boss intake is better than the GT, I understand what ever advantage can be gained in competition use it. I'm not ever going to race my Boss , but I do enjoy going for a good lap time.

The real story always lays with the driver. .

How was his car setup? Similarly? Trying to put your story into perspective is hard when all the facts don't seem to be there.

 

[pufferfish]

ok I found some info on how to calculate the optimum shift point from a dyno graph. first, HP is not a factor, except to say that in general, shift 1000 above max hp is the fastest. I would take it at face value, but I have heard the coyote responds best to 1500 above max, so I set out to waste some time in calculating and graphing both.

so, torque is what propels the car. the fastest way down the strip (or a track straight section) is to minimize the delta between the torque value of the gear you are leaving to the gear you are going into. the rpm that gives you the closest to equal torque is your theoretical shift point.

to plot the graph, you need to find the wheel force for a given gear for the Y and the mph for the X. I started with 500 rpm increments and making my best guess with a ruler to find the torque value at each rpm increment on the dyno graph. then put into the following formula to give me the force the tire exerts to the ground.

(trans gear ratio)X(diff ratio)X(torque value)/1.083

the 1.083 represents the wheel as the lever arm. I use a 26" tall tire (13" radius) and the divider to achieve 1 foot is 1.083, which is important to get an accurate lb per foot figure. with the force numbers calculated for each rpm increment in each gear, all that's left to figure out before plotting is the mph for the given rpm in the given gear. that formula is as follows.

(tire diameter)/2/168X(rpm)/(diff ratio)/(trans gear ratio)

whew! then the fun part, plotting the force at the mph increment in each gear. putting all of these on the same graph shows where each gear parabolic shape intersects. this is the theoretical equilibrium torque value when upshifting.

if I was able to plot these electronically, I could have seen how diff gear ratios effect the shift points, but you all can feel free to do it yourselves...I am stopping here.

each coordinate plotted for each gear represents a 500 rpm increment starting at 2500 and finishing at 8000. the arrows at the 8000rpm coordinate point shows the jump in torque when upshifting. the GT graph is clear that 8000rpm shifts are useless. take the 1-2 gear change for example. at 7500rpm, 1st gear is outputting 3000lb/ft. shifting here starts you off with 3000lb/ft to begin 2nd gear in. stretching to 8000 ends at 2400lb/ft before shifting and getting the same exact 3000lb/ft to start out 2nd. so, the time it takes to get from 7500rpm to 8000rpm is essentially less productive time, which will bring ET's higher.

the GT intake on my car with my gear ratio, is optimized at 7500 for 1-2. 7400 for 2-3. 7250 for 3-4. and 7250 for 4-5. but of course, if I was at a drag strip and was able to do better than 120mph, I would stretch 4th to save the time in shifting. so, with max power coming in at 6600, I am actually shifting LESS than 1000 above max horsepower. very surprised by that.

the BOSS intake graph shows that the 1-2 shift should occur somewhere north of 8000. maybe 8800? the 2-3 is also higher than 8000. the 3-4 and 4-5 are a tad bit higher than 8000, but it would likely be negligible.

what I find very interesting is the force delta you end up with for each intake if you have to short shift as you would likely do on a road course for various reasons. I will stick with 3-4 starting at 5500rpm, since I believe that will be the most common for me.

5500: GT = -400lb/ft, BOSS = -475lb/ft
6000: GT = -310lb/ft, BOSS = -350lb/ft
6500: GT = -250lb/ft, BOSS = -250lb/ft
7000: GT = -150lb/ft, BOSS = -150lb/ft

at 7250, where the GT shifts, is where the BOSS maintains higher force values, over the GT in the next higher gear. at 7250, the BOSS has and additional 150lb/ft. at 7500, +100lb/ft. at 8000, +25lb/ft.

so, carrying a gear higher indisputably allows for more acceleration. and it appears that shifting anywhere above 6000rpm can allow the BOSS intake to never see its low end deficiencies.

its clear to me from this little math exercise, that on paper the BOSS is king for track and drag, with the exception of the short end of the track. up to about 25mph, the GT is supreme.

so, the choice to use the GT intake for road racers has to be because of the hp to weight rules. if you can't wind the BOSS out above 7000rpm (where it bests the GT in HP), its no better than a GT intake. now, on the street, the GT intake is definitely the better choice...but I don't think anyone was arguing that.

the force losses at 5500 are significant, but again, would probably improve for the boss mani with a steeper diff gear ratio.

 

[EJR]

IMO... this whole arguement is void... because gearing plays a huge part in it... So you cant directly compare intakes.

I would never drop to a GT intake to pick up tq. I wish i could take everyone for a ride in my car. You would think it makes double the tq it actually does...

 

[BMR Tech]

Gearing does play a large role. Putterfish made an excellent post, and it touches on what I was referencing in my post.

That said, the best way to determine shift points is by datalogging acceleration rate and force. It is 100% absolute - they will directly reflect in the ET.

I do agree that it is void if you compare two completely different intakes, with two different purposes....on a car that is geared more towards, or bias towards, on of the intakes. In this case, a lower numerical gear ratio will be be more bias towards the GT intake.

EJR, that is likely because you ARE actually making the torque....although you don't see it on a dyno sheet.

Force = (Engine TQ) X (trans gear ratio) X (rear end ratio)

Assuming 1:1 gear in trans (makes it easy)

300ftlbs X 1 X 3.55 gear = 1065
275ftlbs X 1 X 4.10 gear = 1127

In this case, the car/combo with 25ft lbs would have a substantial amount more force pushing the car forward...so, it would be quicker.

On top of that, once you past a certain RPM, the "peaky" curves actually make more TQ up top, so then it simply freight trains the "broad" curved car...

 

[Ultrakla$$ic]

My Boss intake is better looking than my GT intake so the Boss it is.

What's the equation for that? Lol!!!!

Good read guys!:beer:

 

[Deranged2013]

Nice work BMR and Puffer. Very good read.

 

[darreng505]

ok I found some info on how to calculate the optimum shift point from a dyno graph. first, HP is not a factor, except to say that in general, shift 1000 above max hp is the fastest. I would take it at face value, but I have heard the coyote responds best to 1500 above max, so I set out to waste some time in calculating and graphing both.

so, torque is what propels the car. the fastest way down the strip (or a track straight section) is to minimize the delta between the torque value of the gear you are leaving to the gear you are going into. the rpm that gives you the closest to equal torque is your theoretical shift point.

to plot the graph, you need to find the wheel force for a given gear for the Y and the mph for the X. I started with 500 rpm increments and making my best guess with a ruler to find the torque value at each rpm increment on the dyno graph. then put into the following formula to give me the force the tire exerts to the ground.

(trans gear ratio)X(diff ratio)X(torque value)/1.083

the 1.083 represents the wheel as the lever arm. I use a 26" tall tire (13" radius) and the divider to achieve 1 foot is 1.083, which is important to get an accurate lb per foot figure. with the force numbers calculated for each rpm increment in each gear, all that's left to figure out before plotting is the mph for the given rpm in the given gear. that formula is as follows.

(tire diameter)/2/168X(rpm)/(diff ratio)/(trans gear ratio)

whew! then the fun part, plotting the force at the mph increment in each gear. putting all of these on the same graph shows where each gear parabolic shape intersects. this is the theoretical equilibrium torque value when upshifting.

if I was able to plot these electronically, I could have seen how diff gear ratios effect the shift points, but you all can feel free to do it yourselves...I am stopping here.

each coordinate plotted for each gear represents a 500 rpm increment starting at 2500 and finishing at 8000. the arrows at the 8000rpm coordinate point shows the jump in torque when upshifting. the GT graph is clear that 8000rpm shifts are useless. take the 1-2 gear change for example. at 7500rpm, 1st gear is outputting 3000lb/ft. shifting here starts you off with 3000lb/ft to begin 2nd gear in. stretching to 8000 ends at 2400lb/ft before shifting and getting the same exact 3000lb/ft to start out 2nd. so, the time it takes to get from 7500rpm to 8000rpm is essentially less productive time, which will bring ET's higher.

the GT intake on my car with my gear ratio, is optimized at 7500 for 1-2. 7400 for 2-3. 7250 for 3-4. and 7250 for 4-5. but of course, if I was at a drag strip and was able to do better than 120mph, I would stretch 4th to save the time in shifting. so, with max power coming in at 6600, I am actually shifting LESS than 1000 above max horsepower. very surprised by that.

the BOSS intake graph shows that the 1-2 shift should occur somewhere north of 8000. maybe 8800? the 2-3 is also higher than 8000. the 3-4 and 4-5 are a tad bit higher than 8000, but it would likely be negligible.

what I find very interesting is the force delta you end up with for each intake if you have to short shift as you would likely do on a road course for various reasons. I will stick with 3-4 starting at 5500rpm, since I believe that will be the most common for me.

5500: GT = -400lb/ft, BOSS = -475lb/ft
6000: GT = -310lb/ft, BOSS = -350lb/ft
6500: GT = -250lb/ft, BOSS = -250lb/ft
7000: GT = -150lb/ft, BOSS = -150lb/ft

at 7250, where the GT shifts, is where the BOSS maintains higher force values, over the GT in the next higher gear. at 7250, the BOSS has and additional 150lb/ft. at 7500, +100lb/ft. at 8000, +25lb/ft.

so, carrying a gear higher indisputably allows for more acceleration. and it appears that shifting anywhere above 6000rpm can allow the BOSS intake to never see its low end deficiencies.

its clear to me from this little math exercise, that on paper the BOSS is king for track and drag, with the exception of the short end of the track. up to about 25mph, the GT is supreme.

so, the choice to use the GT intake for road racers has to be because of the hp to weight rules. if you can't wind the BOSS out above 7000rpm (where it bests the GT in HP), its no better than a GT intake. now, on the street, the GT intake is definitely the better choice...but I don't think anyone was arguing that.

the force losses at 5500 are significant, but again, would probably improve for the boss mani with a steeper diff gear ratio.

Steve,
As a side note to this thread I've been looking for this info to program my progressive shift light!!! Thanks man!!

An interesting study from your calculations would be to see if this web app is close.
http://www.teammfactory.com/gear-calculator

 

[12C/OBoss]

Have you run past 8200 on your car as of yet? Back in April 2011 Jon Lund and I ran with no limiters on 2 runs and recorded 8400 and 8450 max RPM on a Mustang dyno at Evolution. We decided that while I was n/a to run the soft ecu limiter at 8100 and the hard limiter at 8250 as the crank pulse ring was not available yet and no one even thought of running a Boss past 8000 RPM:banana:


I thinCJ intake, cams, stiffer valve springs, and crank pulse ring there is no reason the Boss cant make close to 500 RWHP and rev to 8500 all day long. Long tubes with no mufflers, and race gas would be needed. Only thing i would worry about is the clutch at those RPMS!!! I literally made hundreds of 8200 RPM shifts and then supercharged it to over 780 RWHP and the only issue I had was clutch stay out at high rpm. Factory clutch was great even at 900 crank HP!!:rockon:


Anyway Puffer i love what you are doing and wish you luck!!!op::beer: