Holley Sytemax intake vs Cobra, numbers inside

All,
I have been doing alot of research lately regarding the Holley Systemax II upper/lower intake manifolds vs the Stock Cobra upper/lower intakes on a blown 302.
What I found is on the attached picture, originally made as an excel spreadsheet but now a .bmp file. I did comparisions of dyno numbers throughout the rpm range, peak hp/tq, average hp/tq from 2500-6000, averages from 2500-4500, averages from 4500-6000, and averages from 5000-6000. I also noted the total gain/loss broken down by engine rpm.
This test was done at AFM and was in an issue of 5.0 mustang I beleive, however I broke it down a little better than they did, giving more specifics.
The car was a stock 5.0L block, vortech S-trim I am assuming w/ stock pulley, stock cam, TFS heads untouched, shorty headers, x pipe, bassani muffers, MSD, Pro-m 80,PMS, 3.73, and T-5.
so by the looks of my Excel file, is the Holley Systemax really worth the price over a stock cobra??
you decide,,all suggestions welcomed.
P.S if anyone wants the Excel document sent, its neater and easier to read, I can send it in email.
Dan

numbers:
Cobra is on the LEFT and holley on the RIGHT

Nice job on the spreadsheet... so basicaly the Holley from their tests is way down (basicaly) till the mid 5k rpm band... interesting. I wouldn't have figred... I would like to learn more about it. I knew that it would flow more up top, but down low, I wouldn't have figured it would have been down that much. That shows that the Holley is definately not as matched as the cobra with the TFS heads.

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Originally posted by WA2FAST
Nice job on the spreadsheet... so basicaly the Holley from their tests is way down (basicaly) till the mid 5k rpm band... interesting. I wouldn't have figred... I would like to learn more about it. I knew that it would flow more up top, but down low, I wouldn't have figured it would have been down that much. That shows that the Holley is definately not as matched as the cobra with the TFS heads.

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I agree, and the funny thing is, I would be willing to bet that it would change w/ different head combinations, and cam combos. That car had a stock cam shaft in it.
However, it appears that for the power level, which you and I may be around, the cobra intake manifold shines in the low and mid revs. I also saw the Edelbrock Performer manifold, w/ that combo it did very well too..( not the RPM)
So for now, despite what info I have found I am gonna stick w/ the cobra, and may have the lower matched to the heads.
BTW, the spreadsheet looks alot neater than that.
Dan

Any other takes on this?
I spoke with a friend, and he really believes that its the 5300-6000 rpms I should be looking at, as I will be shifting at higher rpms when racing anyways. It just seems that w/ the tfs heads, and stock cam, the holley loses too much down low and in the mid range.
I wonder how much a cam such as the E-303 would change the power curve?


Dan

For racing at the track, you should be looking at 4800 and up... that is going to make your numbers, but at the same time, if it is street driven, the power down low is really nice to have... but again, on the other hand, is the 30 you are losing REALLY going to make a difference... I mean, our cars aren't really hurting by losing a little torque, generaly we have some to spare.

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Originally posted by WA2FAST
For racing at the track, you should be looking at 4800 and up... that is going to make your numbers, but at the same time, if it is street driven, the power down low is really nice to have... but again, on the other hand, is the 30 you are losing REALLY going to make a difference... I mean, our cars aren't really hurting by losing a little torque, generaly we have some to spare.

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I guess its kinda hard to say. I talked with a guy from Kauffman Motorsports, and he was chatting w/ one of his mechanics, and the guy informed him that the runners on the holley would basically swallow the GT40X head runners. However, several people have told me that the holley would match up well, via my PM I sent you. also based on the numbers above on the dyno comparisons, it makes me real sketchy about losing power down low.
In the 1/4 mile you gotta have that low end torque to get you moving, and when I have sticky tires Im just not up for losing any power down low, well possibly a little if I could make it up in the mid/up top enough.

Dan

I agree... it's a toss up, it really is. There is no doubt that the runners are larger than the X heads ports. No question. The thing is though, is do you plan on ever getting new heads? Because you might lose a little torque right now, but your gains in the future will be so worth it. Also, cam's change everything as far as torque curves... if you have a really torquey cam, you aren't going to lose as much as the stock cam did.

I have to agree that the cam will be a major factor in the intake choice. The stock cam is made to make torque and only rev to about 4800 and thats about it. If you put a cam in the same motor (like a TFS stage 2) I bet that Holley would shine all over the Cobra from about 3k and up. Although the GT40 and Cobra are great street intakes and all around performers on anything but an all out race motor. Plus you have the option with the cast Cobra upper to have it ported and/or extrude honed for killer flow.

All in all, I think if that test was done on a rather heavily modded, high revving track motor the Holley would have kicked butt, but it's all in what you plan to do with your car/motor...

Exactly... a well matched combo will go a long way as many in the past have proven. I think that the holley isn't neccessarily a great match for the X heads in the way of port size, but combined with the correct cam, I still beleive it will make more power.

What manifold does match the X heads well?

I'm looking at the Track heat or RPM now.

The GT-40 has been proven on my car with my combo and I have seen many cars equiped with ported Cobra intakes that have layed down good numbers as well.

I understand that a ported Cobra is good for much power.

The problem with that is my car is my ONLY car, so I couldn't send the intake out for porting.

I was hoping I could find a good out-of-the-box intake for the GT-40x heads......

GT-40 intake will outflow the cobra out of the box, and it doesn't retain heat like all other intakes... that was part of the reason behind the independent tubular runner design.

So Don, you are running the tubulat GT40 also? I was beginning to think that I was the only person on the planet that still ran that thing. I have been told by some that its hurting me at the level I'm at and others say it will support up to 550+.. I have mine paired with GT40X heads also. I have been debating to keep the GT40 or not, I really like the Holley and the Victor too though.

Yea, I sure do have the origional GT-40 paired with the X heads. It is proven to be a great combo as far as being matched, however I still beleive that there might be power to be made with switching the intake. There have been tests to prove both ways... better and worse, so it's really hard to tell unless it's tested on your car. I think I am going to eventualy switch to a Holley before too long, but that still won't be for a while. The car fund has gotten quite small.

Thats the conclusion I've come to. I am going to tune the car and see what kind of power I can get outta thing FRPP combo and then in the distant future I will probably do TFS heads and a Holley systemax intake. That combo seems to have been proven countless times to make big power. I can see where the GT40 intake and X heads are killer for a mild N/A street car but I think they both suffer a bit when it comes to boost and high revs.

I use to have the cobra intake on my car when I had gt-40 heads and it was a good combination, and my buddy has the x heads and cobra intake which he ported himself, he had the holley on his car and he said it was way slower, so if you want tq stay with the gt40/cobra, but if you can give 10 pftq and gain 30 hp go with the performer rpm,or track heat. very happy with my trick flow r