351W Stroker; 393 vs 408

js66coupe · Jan 3, 2010

I've decided that I'm going with a 351W stroker for my car. One engine builder I've had discussions with wants to do a 408 instead of a 393. Says he can get more power out of it. What would be the advantages of a 408 over a 393? Also, what size heads would work well with the 408, AFRs 185s? TIA.

jerry S · Jan 3, 2010

Advantages of 408: more power
Disadvantages of 408: more expensive, shorter lifespan (the light that burns twice as bright burns half as long)

How much more power from a 408 over a 393? I know a guy with a very streetable 393 who makes 500/500 with a roller cam. Do you absolutely, positively, need more than that? Then go with the 408. But be prepared to pay more money and have a more temperamental engine compared to a 393.

As for the heads, you would want something big if you go 408. At least the 205s but maybe even the 225s if you need insane power. AFR 205s made 560 hp with a roller cam in a 408. If you need more than that, go with the 225s and a 408.

http://www.airflowresearch.com/articles/article046/A-P1.htm

but like I said, I know of a 393W with 500/500 and a roller cam. Do you really need (or want) more that?

htwheelz67 · Jan 3, 2010

a 408 doesnt cost much more if any than a 393, unles you are using your stock 351w rods and 302 pistons, a 393 uses 302 pistons and stock sized 351w rods, the 408 uses 6.2 rods and much lighter pistons, the 408 is a custom engine and there is absolutely no difference in longivety between the two and I would say the 408 is more durable thats just my opinion though, but there were 408's running around way before they had 3.85 stroker cranks for 351w's, the rod to stroke ratio between the two is almost identical. I debated as well and found the 408 was just as cheap and I asked a lot of engine builders and racers before hand and a majority leaned toward the 408. A 4" stroke in a windsor is just about perfect, 393's are great and you can do one cheap but apples to apples the 408 is a better combo and 15 cubes bigger.....

hipo_p51 · Jan 3, 2010

just my opinion, but both those choices are too much motor for that car. the coupe is the lightest compared to a fastback and vert. save some cash, go with a 331.

htwheelz67 · Jan 3, 2010

might as well go big, you will get used to a 331 and want more.......

latamud · Jan 3, 2010

hipo_p51 said:
just my opinion, but both those choices are too much motor for that car. the coupe is the lightest compared to a fastback and vert. save some cash, go with a 331.

If you don't like power. I bought a 408 kit and a 331 kit the same year, same components comparable and they were $100 apart. I didn't build my car for drag racing, the 408 is streetable. If you want to save money go budget 393.

htwheelz67 said:
might as well go big, you will get used to a 331 and want more.......

AGREE!

98GTfromGA · Jan 3, 2010

I would go 408 myself

rbohm · Jan 3, 2010

when building a stroked windsor, going with a 393 or a 408 is like choosing between a 289 and a 302. there really isnt much difference between the two. personally i would build a 393 as you can use stock 351w rods and stock 302 pistons to save money for better heads, preferably the windsor sr heads or the afr 205's.

hipo_p51 · Jan 4, 2010

you also have to take into account the 351 is a wider taller motor and extras will required to make it fit well. the less headaches on a modified car make the project easier. i know you all say some thing, is only 100 buck more. but thats a 100 bucks here, and a 100 bucks there. it adds up. the intakes are more. the larger carbs are more, etc...

i am guessing the orginal poster is just starting out on the project. motor builders have there their favorites. just because one says build the 351w stroker motor, doesnt mean that will be the very best choice. maybe thats why he posted here, to try and find out if there is a better choice.

SadbutTrue · Jan 4, 2010

393 sounds cooler And if you do it yourself you can save yourself a few pennies here and there since it uses off the shelf sized 302 pistons and 351w rods.

hipo p51 - the 351w is a bit wider and taller but there are very few fitment issues, even in a 65/66. It also reuses damn near everything accessory-wise. I also argue with you about the intakes and such... I bought my Stealth used on ebay for $80. 302 intakes might be a bit cheaper but we're talking a sub-$20 difference.

woodsnake · Jan 4, 2010

Either way you go, traction will be a problem for you. Have you planned any suspension mods to compensate for the obscene power your new engine will make??

Tanus · Jan 4, 2010

either way, definatly go with the 205 heads though.

Wicked65 · Jan 4, 2010

I think the biggest difference between the two motors will just be the RPM which they opperate. The 408 probably wont turn as high RPM, More rotating mass.. Othern then that, make it about 10.5 to 1 compression, throw a set of victor jr. heads on, super vic intake and see what she does. nice street car with decent track potential.. add the bottle later if need be.

I find it so funny, guys talking about 500hp being a "insane" amount of power...LOL.. whatever.. My DD has that much.. My 65 should be damn near twice that when im done this spring.. Build it to haul ass, and learn to drive it.. Hell, i had a supercharged fox that would trap 110 that was my dd 8 years ago. And it would snow where i lived. As long as you dont drive like a jerk, you will be fine.

If its too fast, your too old.

latamud · Jan 4, 2010

hipo_p51 said:
you also have to take into account the 351 is a wider taller motor and extras will required to make it fit well. the less headaches on a modified car make the project easier. i know you all say some thing, is only 100 buck more. but thats a 100 bucks here, and a 100 bucks there. it adds up. the intakes are more. the larger carbs are more, etc...

i am guessing the orginal poster is just starting out on the project. motor builders have there their favorites. just because one says build the 351w stroker motor, doesnt mean that will be the very best choice. maybe thats why he posted here, to try and find out if there is a better choice.

I think he's already decided to go either 393 or 408.: 351W Stroker; 393 vs 408... Why try to talk someone out of doing something you don't want them to do? Sure the engine is wider and taller, but it fits. He want's to put a 351 stroker in his car, I support the idea and if he wants to stroke it to a 393 or a 408 by all means, it will fit and he will probably like it. Stroked 351s aren't unreasonable and won't be so outrageous that he can't manage it responsibly. Its an extra 42-57 cubic inches. That's less than 3 12oz beers, or a Big Gulp. It's equivalent to adding about 1 more cylinder/piston to a 351. He's not bolting a JATO rocket to the car.

blown65 · Jan 4, 2010

js66coupe said:
I've decided that I'm going with a 351W stroker for my car. One engine builder I've had discussions with wants to do a 408 instead of a 393. Says he can get more power out of it. What would be the advantages of a 408 over a 393? Also, what size heads would work well with the 408, AFRs 185s? TIA.

Personally I'd do the 408 with no smaller than 205's. Cost would be nearly the same between them unless you get used stuff, but thats easy to do with all the forums and loads of parts you can buy now.

Either one would be good though. 185's would choke it IMO, I know quite a few here seem to think smaller heads, but anyhow.

I'd rather have some HighPorts than AFR.

Clevorguy · Jan 4, 2010

I was planning on a dart 427, then to find out there was no difference in price for me to go to a 438 (my specific scenario)....so 438 I went.

I say go 408.

js66coupe · Jan 4, 2010

Thanks for all the replies. I'm really not too familiar with doing 351W stroker motors.

Originally, I was planning to do a 331. However, the project got way more involved than I thought it would. The front end had some frame damage. The shop working on the car suggested since I wanted to retain the factory look but upgrade the suspension, brakes, steering, etc. that they thought doing a Fat Man Fabrications front end would be better than trying to repair the existing front end. Along those lines, I'm also using their 4 link rear suspension setup with coilovers. This wasn't exactly what I had planned, but once repair labor was accounted for, the front end solution was a better solution IMO.

Any way, fitment won't be an issue with the new front end. So, I decided to go 351W stroker. The engine builder suggested a 408 so I was curious. I figure, I'd be getting a complete rotating assembly for the build so cost shouldn't be a big difference between the two. I may still go 393, I'm just really trying to get pricing from a few sources. I hear Ford offers a 392 with a warranty and that sounds like a good option. Just need to see where the pricing falls on different options.

And yea, I'm concerned about traction being an issue but we'll just have to see. The 289 and C4 have been sold. 351W stroker and C6 is where I'm going now.

js66coupe · Jan 4, 2010

Blown65, so you like the TrickFlows over AFR. Don't Trickflows require a special type of piston for the valve reliefs?

blown65 · Jan 4, 2010

The highports are an inline valve head. Not like the twisted wedge. AFR are good heads too, but a highport will take you further if wanted down the road with more porting. Out of the box though it's tough to beat the AFR heads.

htwheelz67 · Jan 5, 2010

bigger isnt always better 408 is about the best for reliability and strength, 427 is pushing it and any larger on a stock block is.....well you are planning a new engine in the near future.

If you use an aftermarket block and a 4.125 or so bore you can safely have a 460 windsor small block.

351W Stroker; 393 vs 408

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