80FoxCoupe
Well-Known Member
I'm just messing with you. Conservative most times is the best way to go about it, but I like to push the envelope. Do things the way everyone else does, run like everyone else does....
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engineermike
Well-Known Member
@BlueCollarDaily, lowering compression will absolutely lose fuel economy, but probably not measurable if you only drop to 11/1. Per the epa mpg figures, it wasn’t even 1 mpg gain when ford bumped it up. As far as part throttle power goes, I think any differences could be offset by tweaking the torque demand table in the cal. The torque is there but you have to ask for it. This isn’t a turbo where you need na power prior to spool-up. Even if you did, ford, bmw, and others have decided the loss in part throttle torque was either not enough to matter or easily tuned out. Cars like the M3 and GT have much less displacement than the mustang, manual transmissions where lag is harder to “hide”, and they dropped the compression much lower than we’re talking about, yet seem to perform great even at part throttle.
The correlation in bmep vs compression ratio is astounding, even across manufacturers and engine sizes. All the details around turbulence, chamber shape, and control strategy affect it but the chief determining factor of bmep was compression ratio followed by injection type. Lower compression almost always resulted in higher bmep if you’re running at the knock threshold. Furthermore, cylinder pressure vs cylinder temp prior to spark also had an astounding correlation regardless of manufacturer or engine size. It was almost as if there is a physical limit as to what can be built reliably, and as I said, a supercharged 12/1 engine is way over that limit.
If I build an engine for mine, I will be using the limit I referred to above for both CR vs bmep and pre-spark pressure and temp. I don’t have numbers picked yet but my initial thought is a 5.85” rod coyote-based 5.4 at 10.5/1 at around 16 psi on 93. If the cal is right, reliability should approach oem-levels but power and torque will be on par with dedicated e85 setups without the need for e85.
The correlation in bmep vs compression ratio is astounding, even across manufacturers and engine sizes. All the details around turbulence, chamber shape, and control strategy affect it but the chief determining factor of bmep was compression ratio followed by injection type. Lower compression almost always resulted in higher bmep if you’re running at the knock threshold. Furthermore, cylinder pressure vs cylinder temp prior to spark also had an astounding correlation regardless of manufacturer or engine size. It was almost as if there is a physical limit as to what can be built reliably, and as I said, a supercharged 12/1 engine is way over that limit.
If I build an engine for mine, I will be using the limit I referred to above for both CR vs bmep and pre-spark pressure and temp. I don’t have numbers picked yet but my initial thought is a 5.85” rod coyote-based 5.4 at 10.5/1 at around 16 psi on 93. If the cal is right, reliability should approach oem-levels but power and torque will be on par with dedicated e85 setups without the need for e85.
BlueCollarDaily
Well-Known Member
Nice post,
Love this.....
Havent committed Coyote Architecture to memory yet, but what your proposing to moving the piston pin down down then with a shorter rod, but at 5.4L with a 3.701 seemingly being a limit ( that I'd have to jump to a predator block for, even if i had the money $3200-3300 with the ride both ways using my own block is just to much for an 800hp engine ) on bore especially boosting....I assume your talking about going to a stroker crank...god the rod to stroke length ratio/thrust angle is already terrible on coyote...."I run 7.1" rod with a 3.75 stroke crank in my BBC for instance".
I suspect much like earlier stroker LS designs the piston is already rocking at BDC from the distance traveled outside the bottom of the bore at stock stroke...and this with a cast piston when excessive clearance is introduced creates a rocking that begins to flake the plasma bore, once it flakes the ring pack stops oscillating and her comes to scoring.....
As an outsider it would seem though opening the bore would help gen 3 heads ( assuming that's why they went plasma bore to open up to begin with ) pump and that, 4v along with supreme control of valve opening and closing events if why it WILL rpm but objectively it appears to me that the short block isnt really designed for it.....its terrible geometry compared to most others for rpm it just WILL do it because induction is so good....but last how long.
Shortening the rod and adding stroke while alleviating the issue with torque vs compression in this heavy car but for how long and rocking at BDC is an issue as I suspected based on conversations with Piston engineers for choosing the correct piston lately...so bad in fact this company was able to attribute some knock retard to it depending on the QC leaving the plant ( piston on the small side of go/no core matched to bores on the big side go/no go with piston to bore thermal expansion already mismatched due to construction at operating temps)...
If I were to buy a crank I had thought about stroking especially with a sleeved block but people are insane if they think it's worth over 3k using your core for darton sleeves to make 800-900hp...hell naw I could buy a Dart big M and literally make 3k hp for 1000 less than that no thanks....in fact I find it offensive...nothing between stock and 1500hp engine? Plasma or Interlocking darton sleeves? Really that's it no normal economical sleeving?
That means to me I'm stuck with the plasma bore and its properties which really, money permitting leads me into the Predator block for $2200 ready to assemble and factory rated for 13psi already coming finish honed for 94mm....so still shelf pistons at 11 to 1.....
I heard the new iron block wasnt going to be reasonably priced which is a shame because I bet you could really get some bore and stroke out of that with a stable piston especially with offset pins....
It's all very interesting to think about, I hadnt purposely thought about pre spark combustion chamber temps in that manner or phrasing......
12 to 1 is not natural and your relying on sub systems to mitigate an engine that doesn't want to be in that range under boost, as you said the slightest hickup in those sub systems ( what I refer to as tuning window ) and its shows over, including fuel quality and even part QC......
Very interesting to think about, these are the things I looked forward to diving into when swapped platform but failure and failure of prengineered kits/components has taken that head space and time away....
I hope the current engine lives long enough to afford me to luxury of more thought like this and less corner cutting when I rebuilt my core.....you've already convinced me at this point to drop to 11 to 1 and just rebalance....IF I stay boosted.....
If the engine fails quickly, then I'll probably sell the system and build an engine out of my previous core that I'm content with and add power to it when I recover later....but that will never include 3300 for sleeves with me supplying core....Ford owners have a lot of money, I haven't spent this much to accomplish nothing in 30 years cumulatively....but I love the tech and the car.....
Interestingly the 4.70 1st gear was probably meant to overcome the lack or torque but with 10 available I wish 2nd was a bit steeper than 2.98....it feels gimmicky vs well matched...with 10 gears I'd liked have seen less drop between 1-2 then split that change a bit better between the rest with 8th vs 7th being your 1 to 1 and then 2 OD vs 3.....
These days with the torque of my combo being able to jump into 1-2 psi of boost so early and effortlessly in the rpm band with part throttle, I just leave on 2nd with the tune and it's a much smoother experience driving....Lund FTW on that one...
Thanks for the education, I'd be interested to know if you have found sheld parts to complete your theoretical engine build?
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olaosunt
Well-Known Member
I really want to see someone build that 5.4 .
Based on the stroker kit MMR sells ( I am not sure if they use the Callies crank ) you could be out the door (parts only ) for $3000 plus the cost of the block (3.7 bore is required to make 5.4 with longest stroke ).
With the predator blocks going for $2200 that’s like $5200 and $3900 if you use a Gen 3 coyote block (will make about 5.2).
BlueCollarDaily
Well-Known Member
And there's my answer from good ole reliable....I'll probably do it and get shifts much lower if mine can hang in there a while....I'm just used to more torque on tap I think a stroker combo would suit my new Ford life much better and I'd be happier....I'm used to being nimble as hell at 1/4 throttle....my car was INSANELY anemic stock...I mean like shit is there something wrong with it anemic Haha, seriously I drove it straight to the dealership and was like I hear these cars and can run 11s stock this feel like my junker parts runner 300k mile sequoia could smoke it for 300ft hehe literally....lol....god I should have had a camera on my face first time I floored it....it seriously thought something has got to be "wrongWifIt"I really want to see someone build that 5.4 .
Based on the stroker kit MMR sells ( I am not sure if they use the Callies crank ) you could be out the door (parts only ) for $3000 plus the cost of the block (3.7 bore is required to make 5.4 with longest stroke ).
With the predator blocks going for $2200 that’s like $5200 and $3900 if you use a Gen 3 coyote block (will make about 5.2).
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olaosunt
Well-Known Member
“Just do it “ bro . Lol
If you like it ... I may follow (not sure how may “spare “ blocks is too many . Lol)
I would suggest Will@rpgracing for the build as he has done a few already .
He says it requires “balancing the heck out of it”though lol .
BlueCollarDaily
Well-Known Member
Ok that's short hand for a lot of Mallory damn.....
olaosunt
Well-Known Member
Oh oh !
I wonder if the “cheaper “ version of the upgraded 5.2 block is now available (GR3Z -6010-F) ?
It’s showing “in stock “ on some sites .
For some reason it’s does not ship for free either like the KR3Z-6010-A, which is the predator so it may only turn out to be only a couple of $100 cheaper ... and the KR is definitely available .
I wonder if the “cheaper “ version of the upgraded 5.2 block is now available (GR3Z -6010-F) ?
It’s showing “in stock “ on some sites .
For some reason it’s does not ship for free either like the KR3Z-6010-A, which is the predator so it may only turn out to be only a couple of $100 cheaper ... and the KR is definitely available .
engineermike
Well-Known Member
What I had in mind was the predator block and mmr stroker kit. The 3.7” bore and 3.8” stroke brings it to 5.35 liters and 327 cid. My experience tells me piston failure is by far the most common failure mode in supercharged pump gas engines and the ring lands go first even in forged pistons, so preserving the ring land thickness I see as utmost priority. Shortening the rod from 5.93 to 5.85 while adding 0.15 stroke actually gives more room for the ring pack than stock.
The rod/stroke ratio isn’t ideal. It sure seems like the oems have done much better with this in modern designs. But the rod/stroke ratio 5.85/3.8 is still better than a 5.7 rod 383 which was an acceptable improvement over the 5.56 rod 400 back in the day
I’ve been fooling with race engines for 25 years and a mechanical engineer for 20 and I hadn’t thought about it in those terms until about 6 months ago, so don’t feel bad.
olaosunt
Well-Known Member
Great .. I have found another expert (I already bother the heck out of the few I know ) lol
What would the final displacement be if you used the Gen3 coyote block(3.662 bore ) with a 3.84 or 3.9 stroke crank ?
I know it would be < 5.4 but $900 for the Gen 3 block is also << than $2300 for the predator. Lol
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olaosunt
Well-Known Member
Found calculator on line
3.84 stroke crank and 3.662 bore = 5.3L(323.56ci)
3.90 stroke crank and 3.662 bore = 5.38(328.61ci)
https://spicerparts.com/calculators/engine-displacement-calculator
3.84 stroke crank and 3.662 bore = 5.3L(323.56ci)
3.90 stroke crank and 3.662 bore = 5.38(328.61ci)
https://spicerparts.com/calculators/engine-displacement-calculator
BlueCollarDaily
Well-Known Member
I had a feeling you were focused on that ring land area.....even the stock piston to ME seems dang good on the top it does lift that area like the LS I'm used to...on the Coyote its thick and anodized above and below but looks to me gen 3 actually moved that pin height up a hair ( maybe I'm thinking in relation to voodoo) and in ALL my rearch and both my engines it's always the secondary ring land that seems to fail.....which is SO weird for my life experience.....especially just being busted to piece but top and bottom grooves just fine haha....
After yesterday's pull I think something is hosed in trans...its seemed to shift at lower and lower rpm....it flares 1-2 pretty bad...and feel a bit of it holding the gear on downshifting I think between 6-5 and 3-2.....
Also the TQ_CNTL seems to be trying to use AFR for traction control as if it's a freakn NA engine....one company gassing it out another leaning it out....I'll be glad when I can keep it running long enough to do it myself...
Then you have to wait all sunny pretty weekend to get any help after a month of raining....I'm kinda sick of Ford and every other company...I want to go back to the days I was my own support system.....lol....my mind wont let it go while they sleep I'll be miserable.....
I'd love that stroker but it's for SURE getting put on hold if I got to get the trans built...for me may be better to pick one up used swap it in and have the original built well over again longer period of time....
Just really hope to stay running long enough to make the best choices not the cheapest.....
olaosunt
Well-Known Member
So following up on the srtoker .
Since the MMR kit does not the have option for the 3.662 Gen 3 bore , I decided to put /price one together with the Callies crank (it’s a $100 more than the MMR).
Came to $2800 so a little cheaper than the MMR kit
Can any experts comment on the what the ideal length stroke would be ?
I want as much displacement as I can get per bore but I suspect there are disadvantages with going too long on the stroke .
I would be happy with a stroked 5.2 from a Gen 3 coyote block (can get 5.3 with a 3.9 stroke )
The more expensive option would be using a predator block to get a 5,4(as much as 5,5 with a 3.9 stroke.)
Since the MMR kit does not the have option for the 3.662 Gen 3 bore , I decided to put /price one together with the Callies crank (it’s a $100 more than the MMR).
Came to $2800 so a little cheaper than the MMR kit
Can any experts comment on the what the ideal length stroke would be ?
I want as much displacement as I can get per bore but I suspect there are disadvantages with going too long on the stroke .
I would be happy with a stroked 5.2 from a Gen 3 coyote block (can get 5.3 with a 3.9 stroke )
The more expensive option would be using a predator block to get a 5,4(as much as 5,5 with a 3.9 stroke.)
engineermike
Well-Known Member
@olaosunt, to me the key is to maximize displacement while keeping the ring pack dimensions at least as good as stock and the rod/stroke ratio within demonstrated oem limits.
Any additional stroke will require a shorter rod to retain the oem ring land thickness and also avoid moving the wrist pin into the oil ring area. The stock rods are 5.933”. We can use the predator stroke of 3.66” as a starting point since it’s the longest demonstrated by the oem. The distance from the crank main CL to the wrist pin CL is 7.764”. If you back out the shorter mmr 5.85 rod from that number you arrive at a stroke of 3.828”
From a rod/stroke ratio standpoint, I stated earlier that I was comfortable with anything over 1.52 but that 1.48 was certainly too low. I’ve since realized that the LS7 ratio is only 1.516. Assuming the 5.85 rod at a 1.516 ratio gets you a stroke of 3.859”.
The lesser of my two limits is 3.828”. You can see why the longest mmr offers is 3.840”. Keep in mind that these are my thoughts based on the data on hand. Others may have some better data points and others still are willing to push the limits a little further than me.
And a bit of an epiphany...you could actually use the predator block and pistons with the 5.85 rod and 3.840 stroke mmr crank. The result would put the piston top 0.007 higher than stock. If there isn’t enough head clearance (there probably is) you could put a tad thicker head gasket. The result would be 328 cid/5.37L. And, since the displacement is larger then the compression would be higher, at about 9.85/1 as opposed to 9.5. I actually like this idea because you get the oem boost-specific piston design, geometry, and ring specifications plus the ultra-stout predator block and the extra cubes of the stroker crank and more compression.
Any additional stroke will require a shorter rod to retain the oem ring land thickness and also avoid moving the wrist pin into the oil ring area. The stock rods are 5.933”. We can use the predator stroke of 3.66” as a starting point since it’s the longest demonstrated by the oem. The distance from the crank main CL to the wrist pin CL is 7.764”. If you back out the shorter mmr 5.85 rod from that number you arrive at a stroke of 3.828”
From a rod/stroke ratio standpoint, I stated earlier that I was comfortable with anything over 1.52 but that 1.48 was certainly too low. I’ve since realized that the LS7 ratio is only 1.516. Assuming the 5.85 rod at a 1.516 ratio gets you a stroke of 3.859”.
The lesser of my two limits is 3.828”. You can see why the longest mmr offers is 3.840”. Keep in mind that these are my thoughts based on the data on hand. Others may have some better data points and others still are willing to push the limits a little further than me.
And a bit of an epiphany...you could actually use the predator block and pistons with the 5.85 rod and 3.840 stroke mmr crank. The result would put the piston top 0.007 higher than stock. If there isn’t enough head clearance (there probably is) you could put a tad thicker head gasket. The result would be 328 cid/5.37L. And, since the displacement is larger then the compression would be higher, at about 9.85/1 as opposed to 9.5. I actually like this idea because you get the oem boost-specific piston design, geometry, and ring specifications plus the ultra-stout predator block and the extra cubes of the stroker crank and more compression.
olaosunt
Well-Known Member
Thank you again for a lesson even I can understand (sort of . Lol)
Max stroke of 3:84 it is then .
Here is an article about the Caliies cranks below
The 3.8 stroke is what they recommend for boosted applications .”It uses a 2.1 Chevy journal for additional strength and overlap “
https://www.dragzine.com/news/blue-oval-backbone-callies-new-compstar-coyote-crankshaft/
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