GT350 Heads on 302?

[cholmes1]

That's correct, this material is higher quality (read more $$) so combine that plus eliminating the CnC expense would be why the gen 2 design was changed. Engineering is always tasked with cost reductions while maintaining performance goals.

Very interesting. So are you aware of any difference between the stock Boss heads and the Boss 302R heads?

Here is the link: https://performanceparts.ford.com/part/M-6049-M50BR

In looking they have the same valve diameters as the 'improved' GT350 heads in my OP but cost less as they are no longer new.

Best,
Charles

 

[BigTaco]

All of the Boss engines have identical heads; the R head is the "stock" head.

 

[ford20]

A few questions...

1.) Does anyone know what pistons and connecting rods are used in the OEM Boss motors?

In looking at the picture provided by Berol (post #2) and at the 2013-2016 Super Cobra Jet tech specs it appears that using Mahle Forged Pistons and Manley Connecting Rods are in every SVT modified engine. I see the GT350R uses what they just call GT350 forged pistons, but I am curious if they are simply Mahle pistons made for Ford. I would assume ours are cast and not forged.

Here are the tech specs on the CJ setups if you were curious:

http://www.americanmuscle.com/frpp-sc-cobrajet-engine.html#customer_pics-0

https://performanceparts.ford.com/part/M-6007-SCJ16

Assuming we do not have forged pistons or high strength connecting rods...

2.) What is the benefit of swapping them in all of the SVT CJ engines (both forced and non-forced) and in the basic GT350 head swap in post #2?

I was under the belief that our motors were perfectly fine using whipple setups up to 9psi without issue, but now I question that thought.

3.) Finally, in looking at the at the post #2 graphic is states that it was done with long tubes, a tune, and 101 octane fuel. Given that, are these gains really that impressive when compared with the non-FI CJ swap under similar parameters? (To my knowledge none of the write-ups used 101 octane which would certainly bump up values)

Write-Up 1: http://www.enginelabs.com/news/ford-racing-builds-the-ultimate-boss/

Write-Up 2: http://www.mustangandfords.com/how-to/engine/1406-boss-302-bolt-on-upgrades-haul-natural/

Ultimately, based on Seans post "You can get a new set of 2015 heads and a Stage 2 porting and valvetrain work for what you can get for the GT350 heads just as a point of note and I didn't any revised head gaskets. I went with off the shelf Cometic .040 gaskets, but even the factory 5.0 or Boss head gaskets should work as well. I'm not sure if those are cheaper alternatives over the Cometic or not. " I wonder if the GT350 heads really do anything that unique.

Thanks for your knowledge.

1)IIRC my pistons had Mahle stamped on them when I pulled them from the engine, but the rods come from an unknown supplier. The rods are sinter forged like the GT500 rods and can hold up pretty well. The pistons may be forged as well, but don't quote me on that. I haven't seen a set of pistons fail that hasn't been from PTV contact or detonation aside from the #8 issues that the early 5.0's had.

2) They are, 9psi on a Whipple is roughly 550-600HP IIRC so you are a few hundred HP away from breaking the rods which has always been the weakest point of the mod motors. On the Cobra Jet you are buying a $100,000 drag racing car built to run 8's out of the box and dominate in class. The car is purpose built for drag racing and as such you aren't getting the run of the mill internals and Ford Racing wouldn't send you out there with factory internals. With the Whipple CJ you are getting an entire engine that is built around strength and lasting as long as you can which is why it has the internals that it does. If you are worried about them lowering the compression, I wouldn't in all honesty. The coyote loves compression and doesn't mind it one bit. Here is Jeff Polivka's Boss 302 running stock compression IIRC & John Kauderer's Cobra Jet (He pulled the engine and had a whole new motor built for it) running in Coyote Modified.

https://video-lga3-1.xx.fbcdn.net/v/t42.1790-2/14575904_601117536740370_7921335899160313856_n.mp4?efg=eyJ2ZW5jb2RlX3RhZyI6InN2ZV9zZCJ9&oh=a9499daca3168fd00a9f75069b3ea6ba&oe=581A2FA7

For the most part, if you are buying a Ford Racing crate engine, chances are you blew the engine or you are looking for something a bit stronger than what the factory is offering. Most people I see asking about the Aluminator or the Aluminator XS are always curious about how much power it can hold since the next weak point of the coyote is the block itself. When you are buying a crate engine from Ford Racing, once again you are buying a hand assembled engine and Ford Racing is going to put parts in it from the best manufacturers they can, as well as the best parts available to Ford Racing at the time. That is pretty much what Ford Performance is doing here with these two new engines that they showcased. I'm actually a bit surprised that Ford Performance hasn't put out an Aluminator with the 5.2 heads yet.

3) I wouldn't really go off of those write ups in all honesty. One car was making 452 & the other was making ~460 since it didn't give you baseline numbers, but I am assuming a stock numbers of around 380 conservatively. A bunch of other builds using the CJ Intake and Comp Stage 3 cams and such are making in the 480-500 range depending on what fuel they are running. If those two in the writeups were running E85 (which is something usually like 100-105 octane), I'm guessing you would see something like 470 & ~480 so if you remove the 12% drivetrain loss that the Boss has you are coming up with 524 & ~ 537. With the better flowing heads I can see it picking up some more power especially with the more than likely ARH headers over the Dynatech and the 4HP over the red cars setup which used the ARH headers as well. If I were going to give out advice on a NA combo, I would grab a set of custom grind cams and go at it that way. With my car I am making more power on 93 octane at the wheels than those two cars projected numbers on E85 are at the crank. When you are building a NA motor, it is all about choosing the right parts and getting the right combo and going from there and seeing what your pocketbook and hold up to. If I had to do my build all over again and if the GT350 heads were available at the time, I would have grabbed a set of them. Go ahead and do some flow testing on them and see what the numbers were like and if there was some benefit to porting them I would go down that route as well maybe I would get over the 600 mark. With the better positioning of the valves, higher flowing runners, lighter weight, trick valves, and the springs being capable of holding 8200RPM (which is as far as our ECU can go), I think as is in the stock configuration is nothing but a win. Instead I got a set of 2015 GT heads and had those ported and am where I am.

 

[cholmes1]

All of the Boss engines have identical heads; the R head is the "stock" head.

More for tracking and information. Thanks again to all those who have provided insight. Certainly a mod I will be doing in the future.


GT350 Heads: https://performanceparts.ford.com/part/M-6050-M52

38.3mm intake valve and 32.5mm exhaust valve

Boss Heads: https://performanceparts.ford.com/part/M-6049-M50BR

37mm intake valve and 31.8mm exhaust valve

GT350 Cams: https://performanceparts.ford.com/part/M-6550-M52A

14mm lift / 270 degree duration - intake and exhaust

Cobra Jet/Boss Cams: https://performanceparts.ford.com/part/M-6550-M50BEXH

13mm lift / 260(I) 290(E) degree duration - intake and exhaust

Cobra Jet Intake, Dual 65mm TB, and FRPP CAI: https://performanceparts.ford.com/part/M-9000-M50CJ


For Sean's posting, they do have an Aluminator with 5.2 heads: http://performance.ford.com/enthusiasts/media-room/2016/09/first-look-at-the-5-2l-aluminator-xs-crate-engine.html

 

[BigTaco]

FYI, there is a display car at the SEMA trailer (2017 GT) with the new 5.2 Aluminator XS motor in it. 580 HP

The car also has Kooks long tubes and Boss style side pipes.

 

[captdistraction]

Reviving this one. Looking at heads now for a future build and have 3 options (from cheap to spendy):

S550 GT head: flows similar to boss, but heavier valves and different aluminum.
Boss 302 head: 2x cost, stainless valves (sodium filled on exhaust), and better aluminum for heat transfer/managment
GT350 head: 3x cost, same as boss head but mo betta, requires specific cam set, also has valve shrouding issues and P2V becomes a concern for certain piston sets (some machining required depending on setup, but I have no further info there).

For life at 7800 RPM and below for 1 hour at a time, where do I go and why?

 

[cholmes1]

Reviving this one. Looking at heads now for a future build and have 3 options (from cheap to spendy):

S550 GT head: flows similar to boss, but heavier valves and different aluminum.
Boss 302 head: 2x cost, stainless valves (sodium filled on exhaust), and better aluminum for heat transfer/managment
GT350 head: 3x cost, same as boss head but mo betta, requires specific cam set, also has valve shrouding issues and P2V becomes a concern for certain piston sets (some machining required depending on setup, but I have no further info there).

For life at 7800 RPM and below for 1 hour at a time, where do I go and why?

Which direction did you end up going? What was your reasoning and result?

 

[captdistraction]

I found a pair of new in box boss heads. They're the best option for what I'm doing. Swapped some PAC-1234x springs on to them and ran L&M intake cams with boss exhaust cams. I have no idea what this rig will make since the world ending closed the local dynos. Since I stuck with a gen1 timing system the boss head was the best choice for my application.