Firepower354
Famous Member
With a pretty aggressive compression ratio, and made 305lb @2500, over 20% under OP's fantasy
Over 10% more than the peak, that came at 4000, of a well built, tuned TV build, is still a fair stretch
Custom cut aluminum pistons
- Thread starter Tbone3366
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With a pretty aggressive compression ratio, and made 305lb @2500, over 20% under OP's fantasy
Over 10% more than the peak, that came at 4000, of a well built, tuned TV build, is still a fair stretch
I'm referring to the video entitled "The Buzzen Half Dozen"
In that video the 300 six made 335 ft lb at 2750 rpm before they put the 1" spacer under the carburetor.
I don't see a problem if you substitute a "Clean Slate" aluminum, high port, high velocity head along with a long runner intake manifold with port injection.
Use a camshaft profile that matches the power band goal.
A 10:1 compression ratio will not be a problem with an aluminum head.
Firepower354
Famous Member
I'd suspect that the 2500 figure could be met with conventional, realistic efforts. Good head, aggressive ramp cam, long runner intake and exhaust, tight squish pistons matching the chamber shape, the usual. These Mitty-esque histrionics are an amusing distraction though
Your probably right.I'd suspect that the 2500 figure could be met with conventional, realistic efforts. Good head, aggressive ramp cam, long runner intake and exhaust, tight squish pistons matching the chamber shape, the usual. These Mitty-esque histrionics are an amusing distraction though
If you tune the intake and exhaust systems specifically for 2500 rpm I'm sure you can get close with an existing head.
Bench racing is always fun and free.
You never get to hear it backfire though!
Because its going to be a new block, i was looking to increase the rod length up to 7.0 inch, how far should i space the ring lands though and how far up should i place the compression ring, should i gas port it? I know having an exceptionly smooth finish on the head and piston will improve the knock resistance along with the aluminum head
I was thinking of making a dome in the shape of the head with a ring on the outside to bevel in and help increase compression
Firepower354
Famous Member
No need to raise the deck, or go much past 1.7:1 on the r/s if the head is to be that good and the revs that low.
Agreed.
179 HP @ 2500 produces 375 ft lbs. I still propose that a properly cam'd ported head 300 with factory EFI intake, correctly fuel-tuned, could come very close to this target.
Agreed, but Tbone wants to do his own thing which can provide a lot of new information one way or the other. I like it.
If the block deck height is still going to be 10.00" then a 7.0" rod length is about the limit and still have good room for piston rings.
Here is one of my 300 pistons on a 6.8" rod.
Notice the piston pin is up into the oil rings so you have to use a bridge ring on the bottom of the oil ring pack.
The groove between the first and second ring is an accumulator groove.
This groove machined in the 2nd ring land adds to the volume between the top and second ring.
This groove accumulates residual gasses from combustion which alleviates top ring flutter and premature second ring wear, improving ring seal.
Part of the ring spacing depends on the material you will be using in the piston.
If it is brittle, then you want a wider spacing to prevent broken ring lands.
If you are looking for fuel economy use a thin metric ring that has less piston drag and better cylinder seal.
The thinner metric ring pack is more compact and can stay away from the piston pin bore.
Do not gas port a street driven piston. The ring wear is substantially increased.
A flat top piston offers better flame propagation over a dome piston.
Besides that, a flat top piston gives you an 11:1 compression ratio with the standard pre- 1987 300 six.
You will probably need a piston dish.
If that is the case, the inverted dome piston which mirrors the combustion chamber offers the best combustion efficiency.
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Good to know, some more background on what i do, i just got done with a bunch of turbo builds for the mazda 4 cyls, and tuning for those along with lots of machining experience and bachelors in digital engineering, with that experience used to huild the mazda 4s, i have a solid grasp on those, i dont have much experience in builing NA engines, ive made pistons for turbo apps, but the NA stuff is foreign to meAgreed, but Tbone wants to do his own thing which can provide a lot of new information one way or the other. I like it.
If the block deck height is still going to be 10.00" then a 7.0" rod length is about the limit and still have good room for piston rings.
Here is one of my 300 pistons on a 6.8" rod.
Notice the piston pin is up into the oil rings so you have to use a bridge ring on the bottom of the oil ring pack.
The groove between the first and second ring is an accumulator groove.
This groove machined in the 2nd ring land adds to the volume between the top and second ring.
This groove accumulates residual gasses from combustion which alleviates top ring flutter and premature second ring wear, improving ring seal.
Part of the ring spacing depends on the material you will be using in the piston.
If it is brittle, then you want a wider spacing to prevent broken ring lands.
If you are looking for fuel economy use a thin metric ring that has less piston drag and better cylinder seal.
The thinner metric ring pack is more compact and can stay away from the piston pin bore.
Do not gas port a street driven piston. The ring wear is substantially increased.
A flat top piston offers better flame propagation over a dome piston.
Besides that, a flat top piston gives you an 11:1 compression ratio with the standard pre- 1987 300 six.
You will probably need a piston dish.
If that is the case, the inverted dome piston which mirrors the combustion chamber offers the best combustion efficiency.
I achieved a theoretical 345ft/lb at 1800rpm on a pretty mild build. Would it indicate I have a higher velocity, lesser flowing head, smaller cam, or...?
How did you achieve a theoretical result. Simulation program?
Chassis dyno I've posted here before.
Please recap your engine build.
Unknown high mile 1985 bottom end pulled from a rotten truck - high blowby, Comp 268H cam, self "ported" 240ci head, head matched Offenhauser C intake manifold, Edelbrock 500, head matched 87+ EFI exhaust manifolds, 2.5 to 3" Mandel exhaust, 2.5" glasspack, 3" Dynomax muffler, Pertronix I ignitor, Pertronix Flamethrower coil, home recurved distributor 30-32* max(can't remember), electric fan, and a gutted oil bath intake with 14x2" Spectre filter added. No dyno tuning done. A/C and dual sheave 130A 3G alternator. 4-speed manual, 2 piece driveshaft, full float Dana 60, 3.73 gear, F250 CREW. https://www.fordsix.com/threads/my-300-build-discussion-dyno-sheets-etc.79909/
It's what we have been saying all along.
The 240/300/4.9 head ports are undersize for the 50 cu inch 300 cylinder displacement even with bigger valves and porting.
As a result, the more duration and lift you add with street cams, the wider the power band gets including low end torque.
Those with 220 degree cams and .500" lift and big valve ported heads make a ton of power from 1000 to 5000 rpm.
A 232 degree cam with 2.02"/1.60" valves, ported head and 1 1/2" tube headers breaks the tires loose at 1200 rpm and makes power to 5500 rpm.
It would be interesting to see what would happen if you put the Chevy 1.75 ratio rockers back on the head.
The 4032 alloy has less thermal expansion than the 7075
I assuming you would temper the 7075 to T6?
You mentioned 4.25" bore.
Will the bore spacing stay at 4.480"?
Will this be a cast iron block?
Will you improve cylinder head sealing by going to a six bolt pattern around the cylinders rather than the present four bolt?
Four bolt or Cross bolted main caps?