All Small Six Cost of Building a 250ci VS 300ci

[bmbm40]

Just a couple of thoughts...
A 200 with a turbo can be pretty fast and you can set the boost at level which may not grenade the engine to quickly and would certainly be easier that a 300 swap.
The 250 swap which is doable in the early Mustang and with slightly bumped up compression, 2v carb, cam and headers has power comparable to a stock 289.
Of course any turbo 200 or 250 or 300 will require new axle, suspension, larger radiator etc.

Do you already have a 250 in your 66? Oh I see that you do. You might be able to slot the motor mounts to drop the 250 another 1/2". Does your Mustang drive good now? If so the easiest route would be performance mods on the 250.

 

[Crustang to Mustang]

Would you be willing to do EFI on a 300?

Heck yeah! My Mustang is going to kinda be like a restomod but I wanted to keep the inline. The EFI will fit the vibe better but I'm also not opposed to carburetion.

 

[Crustang to Mustang]

Do you already have a 250 in your 66?

Yes, I do.

 

[pmuller9]

The reason for asking about port EFI is you can cut the lower half of the stock 300 EFI intake manifold and use only the straight section coming out from the head.
Then you would weld on a large round plenum with a throttle body at the end of the plenum.
The valve cover would be the highest part of the engine.

 

[Crustang to Mustang]

The reason for asking about port EFI is you can cut the lower half of the stock 300 EFI intake manifold and use only the straight section coming out from the head.
Then you would weld on a large round plenum with a throttle body at the end of the plenum.
The valve cover would be the highest part of the engine.

This is a good idea. If you modify a couple of big block V8 mounts that should fit fine with the stock Mustang hood.

 

[pmuller9]

Just so you know, we are no longer building high performance 300s with flat tappet cams because of the high lobe failure rate.
After two back to back cam failures last year it was decided to move on to roller cams.
The performance difference is night and day.

 

[Crustang to Mustang]

Just so you know, we are no longer building high performance 300s with flat tappet cams because of the high lobe failure rate.
After two back to back cam failures last year it was decided to move on to roller cams.
The performance difference is night and day.

What's the cost difference?

 

[pmuller9]

What's the cost difference?

A Bullet roller cam and Crower roller lifters are about $1500. They are the only game in town at the moment.
Straub technologies is looking at offering cam and lifters for about $1000 in the near future.

 

[Crustang to Mustang]

@pmuller9 would you mind posting some pictures of some of your builds along with the specs? Just when you get a chance. I would love to see them!

 

[Crustang to Mustang]

If you want something unique, then go for one of the Australia sixes. We have a 250-2v, a Crossflow head, a SOHC and DOHC Barra. Your 300 and 250 logs are very inferior to them. Just as an example a 4 litre barra NA is 195kw, thats almost 270bhp, i doubt you could get a 300 to do that without compromisings its drivability, even the SOHC 4litre was up to 172kw. You must have seen this:-View attachment 23310

I do love the Australian sixes, Aussie! But they are just not doable in the U.S. I am happy that you have an engine that you can be proud of and you should be (It looks great!), but it just isn't practical for we Americans.

 

[pmuller9]

@pmuller9 would you mind posting some pictures of some of your builds along with the specs? Just when you get a chance. I would love to see them!

I won’t be home till tomorrow night but I can give you a quick rundown on two of them. Both of the engines are competing against V8s.

The first one is in a pulling truck.
It makes about 350 hp at 5200 rpm and well over 400 lb ft of torque at 3600 rpm.
Stock block bored .050” over with DSS pistons and Molnar rods.
10:1 compression ratio.
Bullet billet steel roller cam.
Intake .050” duration 237 degrees, exhaust 247 degrees on a 106 LSA.
Valve lift is .600”
Promaxx head rebuilt with bronze valve guides, 5.010” long Ferrea valves, 1.94” intake and 1.60” exhaust, PAC valve spring 240 lbs closed and 570 lbs open.
Titanium retainers
Harland Sharp 1.6 ratio roller rocker arms.
Manton 3/8” pushrods.
Offenhauser C intake manifold.
650 cfm competition carburetor.
Hooker competition headers.
MSD 6AL ignition.

Second engine is in a stock car
Same rods, pistons, head, lifters and pushrods.
Bullet roller cam but with a different profile.
Per the rules, Holley 4412 500 cfm two barrel carb with a custom made intake manifold that has a 400 cu inch plenum.
It makes about 330 hp and just under 400 lb ft of torque.

 

[Crustang to Mustang]

I won’t be home till tomorrow night but I can give you a quick rundown on two of them. Both of the engines are competing against V8s.

The first one is in a pulling truck.
It makes about 350 hp at 5200 rpm and well over 400 lb ft of torque at 3600 rpm.
Stock block bored .050” over with DSS pistons and Molnar rods.
10:1 compression ratio.
Bullet billet steel roller cam.
Intake .050” duration 237 degrees, exhaust 247 degrees on a 106 LSA.
Valve lift is .600”
Promaxx head rebuilt with bronze valve guides, 5.010” long Ferrea valves, 1.94” intake and 1.60” exhaust, PAC valve spring 240 lbs closed and 570 lbs open.
Titanium retainers
Harland Sharp 1.6 ratio roller rocker arms.
Manton 3/8” pushrods.
Offenhauser C intake manifold.
650 cfm competition carburetor.
Hooker competition headers.
MSD 6AL ignition.

Second engine is in a stock car
Same rods, pistons, head, lifters and pushrods.
Bullet roller cam but with a different profile.
Per the rules, Holley 4412 500 cfm two barrel carb with a custom made intake manifold that has a 400 cu inch plenum.
It makes about 330 hp and just under 400 lb ft of torque.

Dang that's pretty good power production!!!

 

[78_200_C4]

Just so you know, we are no longer building high performance 300s with flat tappet cams because of the high lobe failure rate.
After two back to back cam failures last year it was decided to move on to roller cams.
The performance difference is night and day.

Powell Machine Inc sold it flat tappet lifter grinder and is no longer grinding new performance flat tappet cams. They just bought a 2nd cam grinder and will focus on roller cams.

 

[78_200_C4]

78_200_C4,
I think this is the 200 six conversion you mentioned.
View attachment 23314
This could possibly give some fresh ideas about an OHC design for the 240 or 300.
It would be lots of work and expensive.

It would be an interesting thread to start in the Hardcore Inline Tech section of the forum so we don’t muck up this thread with stuff that is available in other parts of the world.

HardCore Inline Tech

Engineering or Scientific theory. Keep it Hardcore only.

fordsix.com

The ProMaxx head for the 240 and 300 does a good job. It’s as simple as it gets to build a fun naturally aspirated big block six. And it’s in a price range that more can afford.

The 3 liter 24 valve DOHC version is limited by ACTC rules to 9,000 rpm and 500 hp.
The old push rod roller cam 3 liter ACTC high starter Falcon six engines produced 380 hp at around 9.000 rpm or more.

 

[drag-200stang]

The front suspension on my Mustang needs to be rebuilt anyways. If I go with the 300ci I will just upgrade to HD V8 shocks and springs.

The front spindle on the 66 I-6 is too small. I broke two with a 200, first time thought it was a fluke. Biggest cause was wider rims and tires and driving like the teenager I was. Think about V8 spindles or some other upgrade and duel master cylinder. O yea the exiting wheel tore off the fender and all brakes where lost because the drum has to be in place or all brake pressure is lost and was heading into on coming traffic.

 

[Crustang to Mustang]

The front spindle on the 66 I-6 is too small. I broke two with a 200, first time thought it was a fluke. Biggest cause was wider rims and tires and driving like the teenager I was. Think about V8 spindles or some other upgrade and duel master cylinder. O yea the exiting wheel tore off the fender and all brakes where lost because the drum has to be in place or all brake pressure is lost and was heading into on coming traffic.

I'm looking into how to keep the front 4 lug (I wanna keep the L6 look.) while upgrading to V8 spindles. And I am planning on installing a dual bowl master cylinder.

 

[63 Sprint]

What complete rearend assembly will you be using?

 

[Crustang to Mustang]

What complete rearend assembly will you be using?

For now the 7.25" with 3.20:1 gears. I will probably get some new leaf springs. But I plan on doing an Explorer 8.8" swap at some point.

 

[pmuller9]

How much power are you looking for?

“Pullin 300” six broke the frame in his F150.
The engine was transferred to an F250 and he just noticed that the frame is now bent on it.

 

[Crustang to Mustang]

How much power are you looking for?

“Pullin 300” six broke the frame in his F150.
The engine was transferred to an F250 and he just noticed that the frame is now bent on it.

About the same power as a 351C. Is that too much?