408w vs 418w

[392cobra]

Right now I have a Ford crate 392w with about 5,000 miles on it.

It comes with a 4.03" bore.

I am thinking about using my Sportsman A351 block and go to a 408w or 418w.

The cylinders should be fine,but if not what is the max safe bore ??
My block would be checked out and machined as needed.

There are a lot of guys with either the 408/410 or 418.
With the bore being the same and the difference being in the rotating assembly (same cost),what makes one choice one over the other ??

What are the pros and cons between the two ???


ANY opinions and feedback would be great.

Thanks

[Ron61]

392,

Mine has the 4.03 bore and a stroke of 4.075 for 416. I have had it since 1996 and no problems. A friend of mne has his at 410 and he went with all light weight rotating assembly and said he sometimes wishes he had stayed with the steel like I did. We both mostly drive on the streets and I have great compression when we are coming down off the mountains and hardly ever touch my brakes and he has to be on his most of the way down. But his will wind up faster than mine does. And he has more horsepower than I do. As for if you will gain a lot by going up to these cubes, I really don't think so unless you just want to. Just my .02¢ worth.

Ron

[Terry Brown]

392:

Well I hit 12,000 and threw my second hypereutectic piston in my FMS 392 crate. If you do NOTHING else, go to forged pistons!!

Since mine is down AGAIN I'm pushing mine out to 427 with forged pistons and crank. Hopefully, I'll finally be bulletproof.

Good luck-
Terry Brown SPF 930

[392cobra]

Ron & Terry,
Thanks for the reply.

I've heard of several the Cobra guys speak about losing
pistons and rods thru the side of the block with the FMS 392.
I haven't heard of any cranks letting go yet.

Been thinking very seriously about this upgrade.I had rather deal with it before it breaks.
I'd like to beable to lean on it and not be wondering if this is the time it blows up.

With 5k miles,at most it would be bored to 4.04
From researching this great website I find that is okay.

I have 1 3/4" primary tubes going to a 3" diameter Hooker merger collecter.The mufflers are Dynomax bullet racing with a 3" core.
This were just built and installed last november.I would like to make them work with the 408 or 418.
It seems like the AFR 205's with a new header flange would work. The 225's with the bigger ports seems to need 2" primary tubes (???). Really need advise in this area too.

With both the 408 and 418 having forged everything,
what would make you choice one over the other ???

THANKS

[Terry Brown]

392:

What really made up my mind was the mechanic who is building the engine after the last "break." He said, "You're bulletproof now with the forged pistons. Only weakness is the crank. You may want to replace that at some point."

Well, the engine was apart and with the ability to easily replace the crank, I figured now was the time. Just more $$$$. Changing the crank modified the stroke and with a different piston I'll be at 427.

Now when I'm asked, "Is that a 427?" I won't have to say, "What's the plate on the fender say, Stupid!" or "Well. no, it's a FMS 351 Winsor stroked to 393 although they call it a 392, etc., etc." My reply now is, "Yes, it's a 427."

Besides, it may even go faster!!

Good luck.


Terry Brown SPF #930 427 ci

[SnakeBitt]

392: Pistons and crank are the weakest links to the crate 392. Go to forged for sure.........nothing like "peace of mind".

I know a guy with a 418 built by Eric @ Performance Engineering. Great motor.....plenty of power. I have a friend with one of Eric's 408's as well (when he was Competition Motorsports). Another nice engine. The 2 engines are withing 35HP of eachother, but that could be changed with different cam / heads (in fact I think the main reason the 418 has more power is because it has AFR 205 heads vs. the 408's Vic Jr. heads). The AFR 205's are (IMHO) about the best heads out there for the Windsor stroker. Awhile back, one of the major mags (Hot Rod, maybe?) swapped the GT40x heads on the 392 crate with AFR heads and that change ALONE produced 70HP.
The manifold on your 392 crate is a copy of the Victor Jr intake, so you really don't need to change that. You may want to try a different cam, though.
Heck, take it all the way to 427 like Terry is. You can do a 4.125 bore with only a 4.0 inch stroke (shorter than the 418 stroke). Plenty safe...........and you can tell people it's a "427".
Check out a company called DSS Racing. They sell stroker kits, reasonable prices, and well made parts.
-Have fun!

[392cobra]

Thanks for your replies !

I decided to go with the 408" from KEITH CRAFT.

Just got done ordering it.

New Sportsman block
AFR 205 cc heads
Eagle 4340 crank - zero balanced
Eagle 4340 H-beam rods
Comp Cam custom grind
Scorpin roller rockers
JE Forged pistons, 10 to 1
Victor Jr. intake
Di Vinci HP carb
ARP crank & head bolts
ARP rod bolts

EST. 570-590 hp @ 6,400 rpm

[MidOHasp]

Fred,

Solid Lifters? Oversized Valve Springs?

570-590 is right if you don't float. Otherwise I'd say 550 at 6300-6400.

But then again, KC is the king of getting more HP than anyone else with the exact same combo... Great head work, magic dust, whatever...

Eric Brown (GreatAsp) had a 418 from Perf. Engineering in Ross making 550+ HP. Eric told him 650HP was possible with bigger valve springs at 7K RPM. Same basic setup as yours, AFR 205's, etc...

My 408 made 508 HP but with an RPM Air Gap intake (more torque) and 185cc AFR heads (again, more torque, less HP). 544 lb-ft. Engine dyno guy said additional 40-50 HP possible if he had a day with my heads (knock down the CNC grooves for a smooth polish). After this season, going to pull it out and do some massaging for fun.

Enjoy your stroker!!

[392cobra]

J.P.,

The cam spec's are : .578" lift 252 @ .050 intake & 262 @ .050 exhaust.

Yes,they are installing the springs for this rpm and they rework the hyd. lifters to get these kind of revs out of it.

Sure going to be a whole different ball game driving this compared to my FMS 392.

Thinking I should settle on a tire brand and start buying stock in it.

Any tips come to mind on first drives in it ??

[MidOHasp]

Very cool. I'm in the planning stages of "engine no. 2" and want revs more than bottom end torque (what I built mine for). I want to turn 7K and figured I can't with hydraulic lifters. I actually want 7500+ RPM and figure I will be running a solid roller cam.

I'm curious to hear how your motor runs at those revs, should be very sweet. I know the difference on mine between 6K and 6300 sounds amazing. I start floating a little bit (I think) at 6300. I'm going to put the 6500 "pill" in the MSD box and see.

I'm running a tad more lift than you (.580") and a little less duration (240 at .050") and there is a noticeable difference in sound from the FMS 392. Also running more compression (10.25:1) than the crate 392.

Similar animals, yours is just on more drugs. In this case, drugs are OK.

PS... Good choice on 408 vs. 418. Personally, I don't like to go past square on the bore vs. stroke. That opinion may have no merits, but hey... most of mine don't!!

[thardin]

Hey guy's,

This thread has me very intrigued. I received my kit last month and have started to research the motor. My feeling is that I would probably be better off looking for HP at higher RPM rather than a big torque motor. It must be tough getting the power to the ground in these things...

Anyway, I believe I will be looking for a 408. I plan to run a dry sump system and a crank trigger ignition. I was told I should go with a smaller displacement if I want to see 7,000 rpm. I understand a lot has to do with valvetrain, but does the rotating mass of a stroker limit you? I read about beehive valvesprings recently, are there any advantages with them for high rpm?

Does the Keith Craft motor come with a dyno sheet? Do they have a similar motor with a little more cam & solid lifters?

Sorry for all of the questions, but I am new to the Ford products. I have always worked on Pontiac's. It will be a trip to get over 5,500 rpm!

[Toby]

Midohasp,

I bet 7000rpm sounds better'n a pretty woman singing. Have always heard that a bulletproof engine at 6000rpm was mucho $$ less than one at 7000. Is the valvetrain the sticking point or the bottom end?

[coyled]

It depends on the application in my opinion. For a street or drag motor, its nice to have more cubes and less rpm and you will be happy. If you want to thrash it on a road course, Any motor turning 7000 rpm or more needs a pretty stout valve train. If you are going to run it hard, 351 ci motors will stay together longer than a stroked version and you will want better valve train components in that case. Shelby was gernading 408's in the spec racers and has since gone to bullet proof 351's with no problems. Scott