Interesting article on Manifolds done by VMP

[Badger]

The stock GT block holds up fine with a 7,500 RPM redline, at least non-aspirated.

I recently surveyed the TMO FB group about this and I´ve been warned not to exceed 7200 cause of lifter float. Some even swore by just leaving the stock fuel cut off at 6800 active. The later recommendation was based on two blown motors.
I would love to spin the car that high and have more of my gears left, but at the end I prioritize a healthy motor.

 

[Grant 302]

I´ve been warned not to exceed 7200 cause of lifter float.

That's good advice. Our 'old' GT heads were not setup to make use of much higher RPM than that. IIRC, they won't even fit larger lift cams without more machining.

Will stay tuned in too see how this turns out.. We have a few club S197 cars that were looking into the upgrade.

The intake might work okay on a Boss engine...but I suspect will still suffer some from the lack of CMC plate control.

 

[Badger]

Yea, I think the lockouts and lack of CMRC control is what is killing it. At least in stock form. I know some guys out there are running the lockouts on S550s, but they also drag race and rev to 8000.

I`ll keep you posted about the next tests we`ll run.

 

[2012-Boss]

If you are not going to spin the motor past 7,000 and you don’t have the charge motion valves to build low and mid-range, then I am not sure changing the manifold is going to gain you a whole lot.

 

[2012-Boss]

I never read the TMO Facebook page, so it took me a while to find the posts. The only thing I really agree with in terms of advice is a possible valve spring upgrade.

If you are worried about spinning the motor past 7,200 just put a set of Boss springs in the heads. The cams are not the limiting factor for RPM. Also, make sure your tuner knows you are tracking the car and is conservative.

In summary, the Boss, Cobrajet, and 2018 intakes are only going to show a big gain if you are willing to rev the motor higher routinely. If you aren’t, just stick with the stock intake.

For what is worth, the 2011 GT engine in CaptainDistraction car had +20k in hard mile being routinely spun past 7,500 before it found its way to his car. It’s still going strong and winning races. It did have Boss valve springs installed early in its life. Take a look at some of the Steve Espo / vodoo child 21 car videos.

 

[Mad Hatter]

Only thing I can add is that you do notice that the cars with stock manifolds really get left behind on the straights after hitting 6800rpm.

 

[Badger]

Yep, springs are on the list down the line. Not something I can do myself right now but it´s good maintenance and a must on the long run.

My only counter point would be that even revving to 7500 does not yield any gains right now. Other than extending the power band, that is. Look at the second graph for reference. The power drops off from 7200 on. You could spin it all the way to 8000 and would not make any significant power over stock.

The idea about this manifold was to future proof the car while making some smaller gains from the get-go.
I`m also keeping in mind that this intake should only show its full potential when adding support mods such as headers, cams, springs, etc.

My biggest surprise is how there are no worthy gains at all.

Edit: The tuner is a drag race shop. They are all kind of confused about my requests and problems and left the rev limiter at 8k cause that is what they do.

 

[Mad Hatter]

Hmm..... Maybe its worth trying out a road race tune from Shaun at AED..... I have no dyno info, but I can feel that the car pulls much stronger then it did before with a Lund tune... Before a pair of ZL1's would pull far away from me in the straights and now they only get a two car length advantage. That must be a significant gain at the top.

 

[2012-Boss]

Only thing I can add is that you do notice that the cars with stock manifolds really get left behind on the straights after hitting 6800rpm.

My only counter point would be that even revving to 7500 does not yield any gains right now. Other than extending the power band, that is. Look at the second graph for reference. The power drops off from 7200 on. You could spin it all the way to 8000 and would not make any significant power over stock.

I think what is being missed in the discussion of having a higher RPM potential is the mechanical advantage you get from running in a lower gear longer. Every time you shift to a higher gear, the multiplication of the engine output goes down.

The transmission combined with the rear end gear ration provides the means of mechanical advantage and multiplies the engines torque output to the rear wheels. The amount of torque multiplication is directly proportional to the gear you select. First gear has a higher multiplication than second, second is higher than third, and so on. In short, given an equal engine torque / power output, the car accelerates faster in a lower gear because of a larger mechanical advantage. By extending the RPM range, you extend the time spent at a higher mechanical advantage which equals greater power applied to the rear wheels.

http://homepages.bw.edu/~katchins/csc131common/a_papers/student2/gearmath.htm

 

[Mad Hatter]

Hmm, I can understand the mechanical advantage but the if you are 50 hp down after 7000rpm compared to a Boss or CJ manifold. It must make a big difference in your speeds at the end of the straights.... Or at least one would think so!

 

[Grant 302]

The cams are not the limiting factor for RPM.

That's only somewhat true with the S197 GT. I know what you mean about the mechanical advantage of staying in a gear, but you can clearly see the drop off starting well before 7,500. But without bigger cams, there will little to gain by spinning up to 8k...at least compared to raising the whole curve, say, 20-30hp and sticking to a 7k limit.

In other words, I don't think that only valve springs or stabilizing the valvetrain for high RPM use is the only obstacle here, and I think stock cams are already limiting high RPM performance.

From what I recall, Steve changed almost everything outside of his '11 shortblock...Boss heads, cams, springs, etc.

 

[Swiss Boss]

Also it doesn't mean that if your limiter is set to 7500 you have to shift at 7500.
My limiter is set at 8000 on my Boss but I mostly shift around 7500 or less on the track.
The extra rpm is only there so I don't have to upshift-downshift just before a turn on certain occasion

 

[2012-Boss]

Ok, I must be looking at the wrong graph. To me, the second graph the OP posted, not the VMP graphs, clearly shows that the ported 2018 manifold and CAI peaked between 6,800 and 7,000 and the power carried through to 7,500. The sharp dip in the end right before 7,500 looks to me like the Dyno operator rolling out of the throttle at the end of the run.

To be clear, I am not and never said to extend the RPM to 8,000. 7,400 - 7,500 yes, 8,000 no.

 

[2012-Boss]

From what I recall, Steve changed almost everything outside of his '11 shortblock...Boss heads, cams, springs, etc.

Steve never got around to installing Boss heads and cams. He did buy some Boss head cores second hand, but never installed them. He also bought CJ cams, but those wound up in the currently being rebuilt 21 car’s new engine.

Steve stopped doing power mods to the 21 car in / about 2015. He moved to the 2016 and now the 2018.

https://trackmustangsonline.com/threads/ford-racing-cobra-jet-intake-thread.4415/page-16#post-160053

Again, the GT cams easily rev to 7,500 with the right intake.

 

[Mad Hatter]

I think the key words were "with the right intake"!!

Sent from my SM-G900M using Tapatalk

 

[Grant 302]

I think the key words were "with the right intake"!!

...*AND* long tubes... It's well known that these engines respond well to long tubes.

Still not convinced that intakes are gonna matter much on the stock cams *and* headers.

I stand corrected about what was done to Steves '11 GT.

 

[2012-Boss]

I should also add that I don’t think the first graph the OP posted is a good point of reference for comparison. The Dyno run ends too early. I think if it had been run to 7,500 you would have seen a sizeable difference in power output between the two intakes. The graph does show that the stock intake is a strong performer up to about 6,800.

 

[Grant 302]

Understood on all counts.

My point was that the cams restrict the peak either way. I understand that the old GT intake drops off earlier and sharply on the top end before 7k. And that it's not really seen on the first chart.

 

[Badger]

Oh boy, we did a lot of testing today.

The biggest takeaway was that the initial baseline read ~10-12whp higher than the updated baseline we ran today. This means the graphs posted prior should not be compared!

Why that is, I don`t know. Maybe the car is loosing power or something on the dyno was off. 388whp as a stock number for a gen1 is pretty stout. The new baseline tops out at 376whp, which is still solid.

This is not a 100% back to back test, but pretty close:
The initial baseline was done two month ago. This one should be ignored.
The "ported 2018 + CAI + tune" was tested a couple days ago.
The "ported 2018 + tune" and "ported 2018 no tune" were done this morning.
The "stock 2011 with stock airbox and no tune" were done this afternoon.

New vs Old baseline:
RED: old baseline
BLUE: new baseline



2011 GT Manifold VS ported 2018 GT Manifold
Completely stock motor, stock airbox, no tune, no headers.

BLUE: Stock 2011 GT Manifold
GREEN: Ported 2018 GT Manifold


Baseline, Tunes and CAI
BLUE: Stock 2011 GT Manifold
GREEN: Ported 2018 GT Manifold
YELLOW: Ported 2018 GT Manifold + tune
DARK BLUE: Ported 2018 GT Manifold + JLT v2 + tune

 

[Badger]

I should also add that I don’t think the first graph the OP posted is a good point of reference for comparison. The Dyno run ends too early. I think if it had been run to 7,500 you would have seen a sizeable difference in power output between the two intakes. The graph does show that the stock intake is a strong performer up to about 6,800.

I am not sure what graph you mean, but I think this is what you are talking about.
The blue graph on the left looks like it has an upwards trajectory. It definitely would be higher than the stock 2011 from here on as the stock one would tank after 6800.
That said, the other pulls on the identical setup and tune which were extended to 7500 show a power plateau and no extra gains.

To avoid some confusion I illustrated it: