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All I can say is that is f'in complicated to tune headers....to take advantage of inertial and wave scavaging. Diameter, length, collector design, steps - all play a role. BMW is a master (when they are not using FI or worrying about US emissions). I used to think I could look at a header design and judge how good it is, but so much more CAN go into the design that I just look at dyno plots now. You can screw up any design if you just focus on one design parameter - like length. it's probably more important to know WHO designed them since it still seems like a dark art.
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I do agree that a dyno chart would be a 1,000-times better but we don't have those so we have to guesstimate on what's available until someone can provide solid dyno data.
I volunteer my car. It is now 100% stock. Maybe Jared will dyno it here in Austin stock, then I "might" add CG race headers with a Cobb custom map with dyno tune by Cobb. Then we could post.
Seems like bandwagons form on this forum and everyone just jumps on without checkout out the data first.
I don't think this is fair to Cargraphic or John @ BGB.
John has provided the GT4 forum with so much honest info for FREE and he has been working with the 3.8 in Caymans for years now.
So when John says things like:
Originally Posted by BGB Motorsports
These are the same race headers we have run since 2009 without 1 single issue. The only changes they made for the GT4 were to improve the ground clearance on the driver's side and accommodate for any changes underneath the GT4. These however are by no means new, prototypes or anything of a test nature. We have sold many sets to race teams (race version) and several customers with 3.4s and 3.8s. We have already done the homework for you.
AND
Originally Posted by BGB Motorsports
I just like these because they're our brain child; Cargraphic made them specifically for us for our IMSA Cayman race program in 2010 and we run these on every single Cayman race car we build. Those headers are on nearly every single IMSA ST Cayman and they are the same ones we had during the 24 Hours of Daytona and 2013 Championship season.
I don't think its a bandwagon or hype train as much as race proven results. I am not trying to take away from any other vendor selling headers, but do you think they have as many race miles/real world testing on theirs?
STAGE 1 GT4 WITH RACE HEADERS ON THE MAHA DYNO MAKING 431 HP & 338 LB/FT @ THE CRANK:
To those that say they want to see just a stock GT4 vs GT4 with ONLY header dyno I say stage 1 is the dyno chart that matters because doing ONLY the headers is wasted without the rest of the package.
Everything needs to work together to get meaningful gains. You need to get more air in (intakes, 82mm throttle body & plenum), you need to get more air out (headers) and you need to tune the air/fuel/spark for this new amount of air in and out.
I don't think this is fair to Cargraphic or John @ BGB.
John has provided the GT4 forum with so much honest info for FREE and he has been working with the 3.8 in Caymans for years now.
So when John says things like: AND
I don't think its a bandwagon or hype train as much as race proven results. I am not trying to take away from any other vendor selling headers, but do you think they have as many race miles/real world testing on theirs?
STAGE 1 GT4 WITH RACE HEADERS ON THE MAHA DYNO MAKING 431 HP & 338 LB/FT @ THE CRANK:
To those that say they want to see just a stock GT4 vs GT4 with ONLY header dyno I say stage 1 is the dyno chart that matters because doing ONLY the headers is wasted without the rest of the package.
Everything needs to work together to get meaningful gains. You need to get more air in (intakes, 82mm throttle body & plenum), you need to get more air out (headers) and you need to tune the air/fuel/spark for this new amount of air in and out.
To those that say they want to see just a stock GT4 vs GT4 with ONLY header dyno I say stage 1 is the dyno chart that matters because doing ONLY the headers is wasted without the rest of the package.
Everything needs to work together to get meaningful gains. You need to get more air in (intakes, 82mm throttle body & plenum), you need to get more air out (headers) and you need to tune the air/fuel/spark for this new amount of air in and out.
So all the people lining up for this headers only group buy are wasting their time?
I dont think its a big ask to see what benefit the headers are providing. Particularly the sport headers which are clearly not used in racing.
So all the people lining up for this headers only group buy are wasting their time?
I dont think its a big ask to see what benefit the headers are providing. Particularly the sport headers which are clearly not used in racing.
John @ BGB has been open and honest about it. All you have to do is search the forums. For example:
Originally Posted by BGB Motorsports
Running just headers would free up mid-range torque and give you some more bump up top with slightly better throttle response; running a race version would further these gains but affect the mixture so much that it would require a revised tune.
Anyone thinking they are getting more than 5-10hp from catted headers alone is kidding themselves.
Here is a dyno he posted from a 3.4L to prove my point. Cayman S 3.4L stock vs Cargraphic Sport header(no tuning):
Originally Posted by BGB Motorsports
I apologize for not having an actual GT4 dyno of them by themselves but in the interest of time and power goals, I accelerated my GT4 project to include race headers and too many mods for it to be relevant...I didn't want to use up a set of Sport Manifolds because i need them to sell to customers. When we raced and developed these longtube headers, I was out for torque gains because I realized that via larger throttle bodies, bigger intakes for more air and tuning and other stuff, we could find more power. I say this a lot so I apologize but it's so much harder to scavenge torque than power so i'm all about low end grunt because unlike on the track, the GT4 lives on the street from 4K to 6K RPM.
The top end doesn't gain anything without tuning. I drive mine on the track, gains below 5000 RPM don't mean much to me personally. I can't and won't speak to what everyone on the forums or group buy plans to do with their GT4 build. I only know what I am doing with mine.
On the top end you wont get much (even with tuning)with just headers, but the mid range gets a very nice bump with just headers which is a good 1st step if you want to do your mods one by one instead of the full-Stage 1 with TB/IPD/Filters/headers/etc.... If you have the headers and exhaust as a minimum then the tuning start to make some extra power (not a lot).
But to be fair, the TB is a must upgrade for the top end power but IMO dealing with the exhaust is probably a better 1st step, less invasive, than going for the IPD/TB upgrade which does require COBB AP or some kind of ECU upgrade/reflash.
I wasn't able to test my car before and after but I'm very happy with the results and I'm sure everyone else, as long as they are realistic about the improvements, will be very happy. Lets' see if someone can so some before and after dyno with just sport headers.......
Anyone thinking they are getting more than 5-10hp from catted headers alone is kidding themselves.
In other applications, I've seen HJS cats by themselves pick up a significant amount of power in an NA car. They are extremely well flowing and the longer the tube and collector before them, the better for scavenging.
@ShakeNBake - Do you have any dyno information from your car when we installed the headers? Do you maybe have the before Cobb run? Lets see if we can get you guys the information you seek! The above dyno information is good but we all want to see stuff in isolation, myself as well. In particular that graph has the benefit of a tune, plenum, throttle body and headers with and without cats. The 2nd graph is the best we have to date because even i don't like manufacturer's dyno information. I'm like the rest of you...i need to see it for myself. I didn't dyno my car with just the race manifolds because at the time i didn't have just the manifolds and didn't get them until the motor was out of the GT4.
and I will be glad to dyno my stock GT4 and post results - then when the headers and tune are on, post again - however, the end result will likely be a month from now or so
05-20-2016, 02:22 AM
