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Once they have the CNC program figured out (all the final tweak have been done - sounds like they have), it would be interesting to see a true just change the heads (an only the heads) dyno test.
Did anybody speak to GPI about these heads? I wonder if what Brian said is true which was something to the effect that GPI is discontinuing their heads because these are so good. That would say something about these heads. Also, wondering if GPI has any results with these on any testing they have done if any?
Did anybody speak to GPI about these heads? I wonder if what Brian said is true which was something to the effect that GPI is discontinuing their heads because these are so good. That would say something about these heads. Also, wondering if GPI has any results with these on any testing they have done if any?
I doubt seriously that GPI would discontinue their small bore LS7 head, that thing absolutely rocks(I owned a set). Is the BTR better, I doubt it, maybe equal, but not better. They had a nice Edelbrock canted LS3 for awhile, but per them, the LS7 was still better. I think theirs and LME have a good lineup of heads. Basically all killer, no filler-everythinh both offer are top notch and have their respective places. I would love to see an Allpro Cathedral vs the BTR just too see what both can do. The flow numbers are a talking point, but the dyno will tell the tale.
I think he means 243CC intake runners, not a 243/799 casting head
That is correct....
Mamo Motorsports offer a 243 cc cathedral head with a 2.165 intake valve that flows 360 - 370 CFM depending on whether it's off the CNC or off the CNC plus hand finished
Killer piece.....everyone that I send a pair of those heads to makes excellent power and torque!
Regarding the canted BTR heads, the million dollar question I keep asking myself.....
Why wouldn't BTR offer a simple dimple CNC program for these heads.....the castings must have been designed from the shape of a prototype piece that I have to assume had optimized port and chamber configurations.
Why wouldn't those optimal shapes have been digitized and replicated via the CNC versus only offering these heads as porter castings only?
Makes no sense to me financially.....your appealing to the 10% crowd instead of the 90% crowd (customers looking to purchase a really good turn key CNC ported product)
Your could sell 10X more heads with just a decent CNC program on these and still offer the unported castings to the porter for guys that want to create their own program
I dont get it.....I simply scratch my head at how they are marketing this product after taking 3 years to finally get here
Time will tell if these are as amazing as everyone hopes they are. On paper they look good but the jury is still out.
The canted valve thing is certainly a plus.....I consider myself cautiously optimistic until more independent results start rolling out or till I can find the time to get and work on a set
Mamo Motorsports offer a 243 cc cathedral head with a 2.165 intake valve that flows 360 - 370 CFM depending on whether it's off the CNC or off the CNC plus hand finished
Killer piece.....everyone that I send a pair of those heads to makes excellent power and torque!
Regarding the canted BTR heads, the million dollar question I keep asking myself.....
Why wouldn't BTR offer a simple dimple CNC program for these heads.....the castings must have been designed from the shape of a prototype piece that I have to assume had optimized port and chamber configurations.
Why wouldn't those optimal shapes have been digitized and replicated via the CNC versus only offering these heads as porter castings only?
Makes no sense to me financially.....your appealing to the 10% crowd instead of the 90% crowd (customers looking to purchase a really good turn key CNC ported product)
Your could sell 10X more heads with just a decent CNC program on these and still offer the unported castings to the porter for guys that want to create their own program
I dont get it.....I simply scratch my head at how they are marketing this product after taking 3 years to finally get here
Time will tell if these are as amazing as everyone hopes they are. On paper they look good but the jury is still out.
The canted valve thing is certainly a plus.....I consider myself cautiously optimistic until more independent results start rolling out or till I can find the time to get and work on a set
-Tony
I agree. The only thing I can think is that they are rewarding their dealers by giving them the first shot at selling them.
But even that is weird. GPI has flow numbers for the LS3 version, but you have to contact Kuntz to get them?
Rewarding dealers......I doubt it. Companies are in business to make money.
I cant think of any good reason to justify this marketing strategy in my book and trust me I have given it alot of thought.....LOL
Maybe the timing with the sale of the company and the changing of the guard.....that's the only thing I can think of.
Still.....you can't design the castings for a good product without having a good product (prototype) to copy it from
Why not digitize that and sell a ton of these AND offer the porting shops the availability to purchase the raw castings
It's just the strangest new product roll out I have ever seen....especially with the length of time this thing has been hyped
-Tony
Tony I agree 100%. I think it has to do with the sale of the company and investing in things. I can not speak to current capacity or there business strategy, but in order to machine and assemble they would need to Hire additional people Plus the machines and equipment. If you listen to what he says in some of his interviews about working with Past vendors The only way to control Quality and ensure consistence is to bring it in house.
IMHO, I think this is a way to get it to market faster and try to recover some of the investment cost. This has been a huge invest on his part. I am just guessing It is easier to offer them this way and get them out there Vs waiting another year to buy equipment and getting set up with a team to machine and build these in house. He is already a couple million into this stage and by the time he secures a few CNC's machines and then some valve seat cutting machines, He could be another million into it and another 6 months to year before its all set up and running.
Again just my thoughts... I don't know him Or what's going on in that camp. For all we know he, or the new investment group could be gearing up in the background. Only time will tell
I think BTR has a port program for these if you ask for it, I've read some people saying they have them on order from BTR. I also heard Brian say that GPI actually has a better LS3 port program than their own version on one of the podcasts. He, also talked about why he did the release the way he did but I forget what he said about that. I suspect some of it is for the reasons already mentioned by 1FastBrick but also, I think I remember Brian talking about some other reasons that of course I forgot. F....in getting old socks. Someone has to invite Brian to this thread, we're all over the place speculating. He used to be one here but got busy and got ran off by "funny people" like most in his position.
I doubt seriously that GPI would discontinue their small bore LS7 head, that thing absolutely rocks(I owned a set). Is the BTR better, I doubt it, maybe equal, but not better. They had a nice Edelbrock canted LS3 for awhile, but per them, the LS7 was still better. I think theirs and LME have a good lineup of heads. Basically all killer, no filler-everythinh both offer are top notch and have their respective places. I would love to see an Allpro Cathedral vs the BTR just too see what both can do. The flow numbers are a talking point, but the dyno will tell the tale.
Just noticed GPI posted this answer under their Q&A for these heads so there is that:
How do these heads flow vs your Max 2.0 small bore LS7 heads? I am building a 403 based on a 4.00 bore and stroke. I would like to use one of these two head types. answer now
Asked by Jeff Yarbrough on April 13, 2026 12:08 pm
A. I haven't done any side by side testing between these two but I think the btr would outperform the max 2.0 head
Rewarding dealers......I doubt it. Companies are in business to make money.
I cant think of any good reason to justify this marketing strategy in my book and trust me I have given it alot of thought.....LOL
Maybe the timing with the sale of the company and the changing of the guard.....that's the only thing I can think of.
Still.....you can't design the castings for a good product without having a good product (prototype) to copy it from
Why not digitize that and sell a ton of these AND offer the porting shops the availability to purchase the raw castings
It's just the strangest new product roll out I have ever seen....especially with the length of time this thing has been hyped
-Tony
he answered this in the podcast I posted, around the 45 minute mark I believe. He said that there were a few reasons. The place they have these cast said that they shrink down to a level that he was not seeing on the heads. To get the as cast versions right, he did a porters casting, to provide work for shops that are not able to do this as often anymore since many manufacturers offer their own cnc heads. So it gives them business and they get word out about the product. Secondly, it gives him time to get the true shrink factor figured out so that they can make the as cast versions. He probably listed other reasons thst in am forgetting but they are the primary ones.
Just noticed GPI posted this answer under their Q&A for these heads so there is that:
How do these heads flow vs your Max 2.0 small bore LS7 heads? I am building a 403 based on a 4.00 bore and stroke. I would like to use one of these two head types. answer now
Asked by Jeff Yarbrough on April 13, 2026 12:08 pm
A. I haven't done any side by side testing between these two but I think the btr would outperform the max 2.0 head
The intake manifold alone could make/break the combo and there is way more thought put into LS7 anything vs cathedral . You can slice it anyway you want, but LS7 architecture is tough to beat. That being said, canted is the only thing that is better on paper, but reality has a way of creeping in. Like I said, dyno and dragstrip will tell the tale. The flow numbers are a talking point, let's see what happens in real life. I'll even add that I think a LT head on an LS block will be better than both. I'm watching closely a select few shops working on those combos. If I had to bet, I would bet on that combo over everything else. Chris1313 made 692whp on a SBE 6.2 LT w/ CID heads and a solid roller. LT heads work.
Last edited by DualQuadDave; May 6, 2026 at 02:01 AM.
The intake manifold alone could make/break the combo and there is way more thought put into LS7 anything vs cathedral . You can slice it anyway you want, but LS7 architecture is tough to beat. That being said, canted is the only thing that is better on paper, but reality has a way of creeping in. Like I said, dyno and dragstrip will tell the tale. The flow numbers are a talking point, let's see what happens in real life. I'll even add that I think a LT head on an LS block will be better than both. I'm watching closely a select few shops working on those combos. If I had to bet, I would bet on that combo over everything else. Chris1313 made 692whp on a SBE 6.2 LT w/ CID heads and a solid roller. LT heads work.
yes time will tell. Also they arent saying the canted cathedral heads will outperform the gpi ls7 small bore heads. They are saying the canted ls3 heads likely will.
Another thing mentioned in this podcast was a comparison between canted cathedral and brodix rec port heads. The canted cathedral only lost out on top by like 10 or 20hp but they were 100ft lbs better at 4000 rpms.
If everything you're stated is correct, 10-20hp is important to some guys. But it appears the canted valve heads have a big advantage in the area under the curve. If you could hook the power, the canted valves heads would would outperform the other heads...
If everything you're stated is correct, 10-20hp is important to some guys. But it appears the canted valve heads have a big advantage in the area under the curve. If you could hook the power, the canted valves heads would would outperform the other heads...
for those that want the greater top end, the canted ls3 heads are supposed to beat just about everything. I was referring to the canted cathedral, which would have the best power under the curve.
I'm just repeating what Brian said in that podcast and what the limited dyno tests have shown. Looking forward to seeing what gets proven time and time again, not just marketing, but my hopes are high. Also very eager to see the price and performance of the as cast heads when they are released.
I know he is a great salesman and probably is able to manipulate me to a degree, but I am not a dummy and the things he says make sense. He also does more testing than others, or at least advertises it more/better, such as spintron testing for the cams to assure safe but effective lobes for power, updated cam versions over time to use what works better, solid track record for springs, millions invested in canted valve heads, using powdered metal guides, etc.
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