If mmr can port coyote heads to flow more than boss heads, then boss heads should be able to be improved too, right?
anyone out there with a set? Worth it? Power increase, if any?
anyone out there with a set? Worth it? Power increase, if any?
Anyone out there with aftermarket ported boss heads?
- Thread starter pufferfish
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That's a good question Steve. You also probably need headers along with the head port too, right? I'm guessing the 1-7/8" variety to match the bigger exhaust outflow?
yeah, a good set of longtubes are manditory for a head like that. i already sold my kooks shorties to plan for some serious exhaust flow. i talked with livernois last week and they told me that on the cobrajet program, they don't do too much to the heads. just a port polish, bowl blending and a different valve job that promotes flow. they obviously couldn't pin down a hp gain, but threw out there that if i go with their porting, it is important to get the right headers. they said kooks offers a step header on a custom basis and that the more steps the better. they suggested at a minimum to do a 1.75 to 1.88, but have seen better results from adding a third step of 2". they said not to go with a full "mmr stage 3" porting, as the boss ports are very efficient and hogging them out would ruin their low lift flow characteristics...or something like that.
RTD, i wouldn't be at all surprised if the S550 used off the shelf boss heads. everything they have said about them does sound like boss heads. bigger valves...yup. better port design...yup. using higher lift cams...yup, cj cams or something close to them would work really well in a street car.
RTD, i wouldn't be at all surprised if the S550 used off the shelf boss heads. everything they have said about them does sound like boss heads. bigger valves...yup. better port design...yup. using higher lift cams...yup, cj cams or something close to them would work really well in a street car.
Make sure whoever works on BOSS heads knows what they are doing, They are far more complex to play with than the Coyote heads.
Livernois information is incorrect, the SCJ and CJ heads both used factory Boss heads with a different spring. That's it.
The Boss heads were a unique casting, there isn't a lot of additional meat in them for porting so be careful...
yes, i made another call to them yesterday and i understood wrong. the CJ does use factory boss heads with different springs. i got confused by them saying they do the cobrajet engines and then telling me what they have found that works to improve the boss heads.
but who says boss heads don't have meat in them? from everything i have read, they casted it with smaller ports so that when the cnc work was done, it ended up with the same chamber and port volume as the coyote heads. this would mean they have the same amount of meat to work with.
but who says boss heads don't have meat in them? from everything i have read, they casted it with smaller ports so that when the cnc work was done, it ended up with the same chamber and port volume as the coyote heads. this would mean they have the same amount of meat to work with.
Last time I've seen the boss heads are untouched in the combustion chamber area, but the intake and exhaust ports were done extensively, volume increased 4-10% depending on the port. But it has been proven quite a few times, that it is always better to work with Coyote heads when porting, more meat on the bones.
no, i assure you the combustion chamber is cnc'd. if i had some time to host a pic and then link it here, i would show you. you will just have to trust me on that for now. you have your 4% and 10% number right, but applying it to the wrong stat.
the magazine articles say the intake flows 4% more and the exhaust flows 10% more than the coyote heads...they do it with the same port volume.
the one part of that stat i think is questionable is the 10% exhaust side increase. the numbers may very well include cams into that flow number. since the intake cams are the same as a coyote, 4% is plausable. but since the exhaust cams are 1mm higher lift, it begs the question that the cams may have been factored in.
the magazine articles say the intake flows 4% more and the exhaust flows 10% more than the coyote heads...they do it with the same port volume.
the one part of that stat i think is questionable is the 10% exhaust side increase. the numbers may very well include cams into that flow number. since the intake cams are the same as a coyote, 4% is plausable. but since the exhaust cams are 1mm higher lift, it begs the question that the cams may have been factored in.
sorry, i mispoke. the difference between the coyote and boss exhaust cam lifts is 2mm, not 1mm.
coyote intake ports are 193cc
http://www.mustangandfords.com/project-vehicles/mmfp-1203-2011-coyote-5-0l-heads-and-camshafts-upgrade/aeromotive-billet-fuel-rails.html
boss intake ports are 193cc
http://www.americanmuscle.com/frpp-boss-head-right.html
also, both heads use a 37mm intake valve, so the port work without additional volume has to be very sophisticated to achieve a 4% flow increase! the exhaust valve increases from 31mm to 31.8mm, so that further explains the larger gain, but there is no port volume information that i can find on the exhaust side of either head.
coyote intake ports are 193cc
http://www.mustangandfords.com/project-vehicles/mmfp-1203-2011-coyote-5-0l-heads-and-camshafts-upgrade/aeromotive-billet-fuel-rails.html
boss intake ports are 193cc
http://www.americanmuscle.com/frpp-boss-head-right.html
also, both heads use a 37mm intake valve, so the port work without additional volume has to be very sophisticated to achieve a 4% flow increase! the exhaust valve increases from 31mm to 31.8mm, so that further explains the larger gain, but there is no port volume information that i can find on the exhaust side of either head.
One might guess that the boss exhaust cam lift contributes a 1% or 2% gain? Leaving a good 8-9% increase from the heads (or some reasonable split)? I agree there probably is not much more meat on the boss heads for porting without giving up some structural integrity. If the ported walls are too thin I'd suspect it would invite heating issues as a consequence? Or is my mind just wandering there?
Are the exhaust manifolds the same on the boss and GT?
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Livernois doesn't assemble the CobraJet engines, PAS does (the same place that builds the Aluminators).
The reason I stated be careful porting the Boss heads is because they are already CNC ported. There is some material left in them but it sucks when you hit water....
livernois said they worked on the development program, not necessarily assembling them. the big bore NA cobrajet block IS FOR CERTAIN a livernois product. wish i had the coin for that baby!
what everyone seems to be missing is the fact that its a different casting that had SMALLER ports than gt heads to be able to cnc port them to get them back up to the SAME volume as gt heads, but with better flow characteristics. there is no reason there would be any less material than gt heads.
MMR also said they have done their stage 3 porting to boss heads already, so I hope that puts this issue to bed.
darren, gt and boss both use the same factory tri-y header.
well, since it seems nobody here has had experience with it, i am taking the plunge and boxing my heads up to go off to livernois. i figure they would be the best suited to optimize these heads than mmr. i don't want to have ridiculous flow numbers that ruin port velocity, just better all around flow.
what everyone seems to be missing is the fact that its a different casting that had SMALLER ports than gt heads to be able to cnc port them to get them back up to the SAME volume as gt heads, but with better flow characteristics. there is no reason there would be any less material than gt heads.
MMR also said they have done their stage 3 porting to boss heads already, so I hope that puts this issue to bed.
darren, gt and boss both use the same factory tri-y header.
well, since it seems nobody here has had experience with it, i am taking the plunge and boxing my heads up to go off to livernois. i figure they would be the best suited to optimize these heads than mmr. i don't want to have ridiculous flow numbers that ruin port velocity, just better all around flow.
Talk to RGR/JPC first! Then PM me
That's who's doing mine, and yes I got GT heads instead of using my Boss heads. Livernois can do SOME work but I'm pretty sure RGR will out do them in every single area as far as quality parts, service and power produced on a NA motor goes the only thing that RGR can't do is be cheaper LOL! I've chatted to some of these guys who work on coyote and boss heads and no one every brought up issues that Rich did which to me signifies either they don't know or they just are trying to sell something. I've decided that when it comes to my build and thousands of dollars being spent I'm going to the best guy in the business for my heads.
I really associate rgr/Jpc with max effort drag racing, which isn't exactly what I am after right now. A road race engine needs a broader curve than a drag engine. Livernois can and offered full porting too, but based on my needs, said not to have it hogged out for max flow potential because it would be way to "peaky" of a power curve. They sold me on LESS work an LESS cost than they could have gotten from me. That and their reputation is what sold me on it. Also' if I find I need more flow in the future, these heads can still get another 30cfm through a big port job. Once you hog them out, there's no turning back.
Hey, at the end it matters we are happy right! So have at it and post results! Yeah it's true I'm looking for a max effort NA build at the moment
your cleaned up Boss heads will produce a beautiful bump in power at a savings of $$$$, I wouldn't doubt 20-25ftlbs and 25-30hp gains through out the power band on them. Sticking with stock boss head gear, meaning valves and springs? New Boss springs aren't expensive and if u could id swing a new set maybe. If not Trickflow stage ones are also an awesome spring which will allow ur tunner the ability to tune without limiters. Rich with his stage 1s coyote heads hit 30hp and 25ftlbs with a change in the heads being the only change on the engine.
i saw that article (killer cardio) and they were impressive gains on the stage 1 heads. i doubt i will see those gains starting with the already better breathing boss heads and working with stock boss cams, but i do think the head work will pick up around 20hp on their own. i am leaving the stock boss valvesprings in, since they work fine with stock cams. whoever does cams for me in the future is going to select their own spring anyhow. i am installing limiters though, at my tuner's suggestion, because if i end up with a freak 8500rpm miss, the valves can contact the pistons. its just a safety precaution.
Ohhh snap, didn't take into account ur keeping stock cams ATM sorry. But yeah should pick something heathy up either way any ideas on who's gonna maybe do the cams for ya?
sorry. But yeah should pick something heathy up either way any ideas on who's gonna maybe do the cams for ya?
that mod will be next year, so i have lots of time to choose. since everyone seems to use comp cams for the cores and grinding, the prices are comparable across the board. i am interested to see how darreng505's mmr road race cams and phaser deletes turn out as i plan on following a similar path for the car down the road.
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