351w engine stroker 393 or 408: significant difference

[skullandbones]

I have the opportunity to build my dream engine which may not be what most people would consider very radical. Right now I have a 302 with maybe 330 hp at the fly wheel. So my new engine will have a forged crank, rods, and pistons it is going to have a manageable 10.3 to 1 CR and a not to radical roller cam but a little more radical than the Ford E303 in the 302. So what really has me thinking is whether a 393 or 408 would be the best choice for CI. I do want the seat of the pants feel of a torquey engine. My past hot rod engines have all been BB Chevy: 366 (348), 409, 396, and 427s. Torque was never a problem. Once I have chosen the CI, I'm not sure if the cam choice would be any different for one or the other. I know there are many varied opinions on bore and stroke ratios: personally I like the bore to be a little larger than the stroke. So I was wondering your opinions on the significance if any, of the 393 vs 408.

There is something that will make this engine a little more special than my past ones. It will have an aluminum block which is 111 lbs (weighed on my accurate bathroom scales) and will have an 8 stack ITB EFI induction. Since most of the driving is local with an occasional road trip, rare track day, and that launch onto the freeway when there is no traffic around. Here are a couple of shots of the block under the Xmas tree. Yeah, had to do it. My machine shop guy liked it, too.

Thank you and Happy. New Year,

WEK

[Gordon Levy]

Give me a call tomorrow, there is a ton to talk about with different packages and the best way to optimize what you have.

[GoDadGo]

My pal Gerry has a 393-Windsor (3.85 Stroke) in his Daytona and I've got a 383-SBC (3.75 Stroke) in my MK-4 Roadster.
> Both cars have similar compression ratios, camshaft grinds, single-plane intakes, and carb CFM ratings (770-vs-800) and both pull like freight trains.
> Wheelspin is easy to achieve in the first three gears in both cars but mine spins in 4th because of my deeper gears (3.73 vs 3.55) and better breathing heads.
> Personally, I don't think you can go wrong with either the 393 or the 408; however, I'm a bigger fan of the shorter stroke 393 over the 408.
> On a similar note, your 396 and 427-BBC shared a 3.75 stroke which is what I have in my 383.
As long as you don't choke the engine with your head choice, either engine will walk the dog on your current 302.

Good Luck & Happy Wrenching!

NOTE:...My Dart SHP Block could have been pushed to 427 cubes (4.125 X 4.00) but I opted for 383 (4.030 X 3.75) instead.
.............It seems to run very cool since the cylinder walls are pretty darn thick.

[Bob Cowan]

With an aftermarket block, you can go as big as 454. Why not build the magical 427? That's what I did.

As for the cam, be careful with that. An ITB system has very different requirements. Because there is no common plenum to draw from, it has to have a slightly less overlap than other engines. Too much overlap creates the dreadful "Weber Cloud". Look for an LSA of 112-114*. Comp Cams used to make cams specifically for these systems.

Also, be careful on the heads you use. If the heads and valves are too big, you'll lose all your intake charge velocity, and all your low end torque.

https://i.imgur.com/KPSihRY.jpg

[johnnybgoode]

I have the opportunity to build my dream engine which may not be what most people would consider very radical. Right now I have a 302 with maybe 330 hp at the fly wheel. So my new engine will have a forged crank, rods, and pistons it is going to have a manageable 10.3 to 1 CR and a not to radical roller cam but a little more radical than the Ford E303 in the 302. So what really has me thinking is whether a 393 or 408 would be the best choice for CI. I do want the seat of the pants feel of a torquey engine. My past hot rod engines have all been BB Chevy: 366 (348), 409, 396, and 427s. Torque was never a problem. Once I have chosen the CI, I'm not sure if the cam choice would be any different for one or the other. I know there are many varied opinions on bore and stroke ratios: personally I like the bore to be a little larger than the stroke. So I was wondering your opinions on the significance if any, of the 393 vs 408.

There is something that will make this engine a little more special than my past ones. It will have an aluminum block which is 111 lbs (weighed on my accurate bathroom scales) and will have an 8 stack ITB EFI induction. Since most of the driving is local with an occasional road trip, rare track day, and that launch onto the freeway when there is no traffic around. Here are a couple of shots of the block under the Xmas tree. Yeah, had to do it. My machine shop guy liked it, too.

Thank you and Happy. New Year,

WEK

Nice! I wish Santa had brought me one of those! Congrats!

[Al_C]

I don't think you can wrong with either choice. There really isn't that much difference (.15 inches in stroke) between the two. So there are two questions in my mind: which sounds better to you - 408 or 393, and which would bring you more happiness? As others have commented, your heads, intake and cam will really determine how this beast turns out! Good luck with it! (and post videos of it running when it's complete!)

[skullandbones]

GoDadGo,

i like the real world view using your and your friend's cars. I get from this that other factors besides the 16 CI really make the difference. So I will take your advice about the heads. Oh! I already did (ha). Really, I got some good breathing ones with 220 int / 80 exh runners. The intakes actually measured out closer to 210 so I am happy with them. Regarding the diff. I love my 3.27 so I am hoping that the added power will overcome the occasional need to gear down now with my 302 like in the mountain passes for instance. The real weak link will soon be my poor T5 which is likely to vaporize with a hard launch or power shift into 2nd! I can see this increasing hp by 80 to 100 easily. So more dollars for trans looks like a possibility. Thanks for your perspective.

WEK

[Jim1855]

WEK,

Just 'cause I'm curious and nosey. What aluminum block are you running? I have the original RDI 9.5 deck and a spare but similar (later production) Ford "Z" block.

Mine is built to 427, 4.125 x 4, single 4-barrel Plenty of power, spins up quickly and drives well. About 65k miles at this time, was new in 2004 but hasn't been run in about 5 years. Will go into my Challenge Car.

Jim

[Bob Cowan]

GoDadGo,

Really, I got some good breathing ones with 220 int / 80 exh runners. The intakes actually measured out closer to 210 so I am happy with them.

WEK

Like I said, be carful about that. I started out with a set of Dart 195 heads, with 2.02 intake valves. The TB's were 58mm (IIRC). Engine made over 500 hp with a very flat torque curve.

Then one day I swapped them out for some Brodix heads with 2.08 valves. I gained a little bit of high RPM HP, but lost all my low end power. Instead of flat, the torque curve looked like a HP curve. I went back to the 195 heads, and all was well with the world again.

When I get home (I'm at work right now) I'll see if I can find the dyno charts.

[skullandbones]

Yeah, it is a Speedmaster or the old PCE. I could not pass up the deal. I figured if it wasn't as advertised I would ship it back. So I took it to my local machine shop (they specialize in racing marine engines). So he looked at it and said,"sweet piece". There was a Brodix World block sitting next to it on the table so I know they work on high end stuff too. They will give it the once over for align bore, bore/hone with honing plate, stroker clearance, check deck, and balance internally. I will do the assembly. So far I have an Eagle forged crank picked out with other forged parts. But this thread was to help decide on CI but other considerations are being brought to light. In my mind I am already building it. Visualization doesn't hurt.

thx,

WEK

[skullandbones]

Hey Bob,

BTW: fantastic looking billet induction system. Did you have that milled. It looks like billet pieces.

i hear what you are saying about the induction/heads/cam situation. My heads were built By the same machine shop as I mentioned. They have 2.02 intakes. Like I said before I didn't think these runners looked that big so I got about 211 cc. when I measured with a hydrometer. Just for kicks I did the chambers which are as published at 62 cc. Also the ITBs are 47 mm. So this may be a close call or on the bubble so to speak. Hope I don't have to downsize!

Thanks for the heads up. Wouldn't mind having your thoughts on a cam for this setup. Remember I' not racing.

WEK

[Gordon Levy]

The block can be built up to 464cid. We just finished one and it's a beast. At 427ci it can make a comfortable daily driver 570hp and 550lbft. It would propel pretty much anything quite well.

[skullandbones]

The block can be built up to 464cid. We just finished one and it's a beast. At 427ci it can make a comfortable daily driver 570hp and 550lbft. It would propel pretty much anything quite well.

Gordon,

Are you speaking of 351 Windsor blocks in general or specific after market ones? I know the Ford Racing version comes in a Big bore version. I, also, remember when daily driver and 570hp/550lbft were not used in the same sentence.

WEK

[Gordon Levy]

The aftermarket blocks, like the aluminum one you acquired are very possible. My production block 408's make 550 all day. There are a ton of differences in the race blocks like the one you have. They use a 2.75" cleveland main and not a 3" windsor main so it is happier at higher revs. It is pretty much a blank slate depending on how you want to use it. 400ci solid roller 8000 revs, 464ci torque monster and everything in between is possible. Cammed and set up properly 575hp can be daily driver reliable, we do it all the time with guys that have many 10's of thousands of miles on their cars

[GoDadGo]

Wek,

Here are two stupid questions for you:

> What is the intended use of the car once the new motor has been installed?
> Are you going to be racing the car, showing the car, or just cruising around in it?

I think once you ask yourself these simple questions you'll be able to decide on what will go in your ride.

Steve

[CSX427]

Back in the day, the 42x Nascar engines all had 3.75 stroke. If you have the 4.125 bore block (and if you don't, trade it), 3.75 stroke gets you 400 inches that will be really happy at 7000+. It will need big heads and a big cam, but it will make spectacular horsepower(600+). Get a light flywheel and dual disk clutch for that race car sound and feel. If you really want to go really crazy, get the CHI Clevor heads and intake and plan on 8000 rpm. If you want a street terror, build a 4" stroke 427 with a little less head (210-220 cfm) and a little less cam (236-240 intake) and prepare to buy lots of tires. Gordon's advice/knowledge on stroke, heads, intake, and cam is spot on. I would change his cam recommendation to a solid roller one step down and plan on setting the valves once a year. If you get squish under .040, 11/1 compression with 93 no-lead works. Good luck and keep us posted.

[Bob Cowan]

Hey Bob,

BTW: fantastic looking billet induction system. Did you have that milled. It looks like billet pieces.

i hear what you are saying about the induction/heads/cam situation. My heads were built By the same machine shop as I mentioned. They have 2.02 intakes. Like I said before I didn't think these runners looked that big so I got about 211 cc. when I measured with a hydrometer. Just for kicks I did the chambers which are as published at 62 cc. Also the ITBs are 47 mm. So this may be a close call or on the bubble so to speak. Hope I don't have to downsize!

Thanks for the heads up. Wouldn't mind having your thoughts on a cam for this setup. Remember I' not racing.

WEK

The system was built by a guy here in CO, Momar Injection. The company is out of business now, unfortunately. Every now and then you'll come across a set up for sale. A lot of people said they couldn't get it to run, and they developed a bad reputation. But the real problem was they picked the wrong computer. Mine ran awesome with a MegaSquirt computer.

As for the cam, there's two important factors to pay attention to:
1. Big displacement will make a "big" cam act smaller. What I mean is that a cam that's pretty radical in a 5.0 will be a lot milder in a 427.
2. ITB's don't do well with a lot of overlap. For example, Comp Cams makes a series called "Thumper". They're designed to have reasonable driving characteristics, but sound really mean at idle and low RPM's. Mostly for the parking lot racers. They accomplish that by closing the LSA down to 7*. Terrible for ITB's.
Look for at least 1128, and preferably 114*. Look at the 5.0 Computer cams on the CC web site.



The aftermarket blocks, like the aluminum one you acquired are very possible. My production block 408's make 550 all day. There are a ton of differences in the race blocks like the one you have. They use a 2.75" cleveland main and not a 3" windsor main so it is happier at higher revs. It is pretty much a blank slate depending on how you want to use it. 400ci solid roller 8000 revs, 464ci torque monster and everything in between is possible. Cammed and set up properly 575hp can be daily driver reliable, we do it all the time with guys that have many 10's of thousands of miles on their cars

This is very true. 550hp can be accomplished in a number of ways. Some of them make the car difficult to drive on the street, and some of them don't. My engine looked radical, sounded mean, and made a butt-load of power. But it was easy to drive and got >20mpg. It could also run on e-85, thanx to the MegaSquirt.

[Bob Cowan]

I initially built my engine with Dart 195 heads. Kind of small for a big stroker, I know. But when I built the car, I had no intention of racing. With a Big'ish CC cam, it made this power. The flat torque curve made it a ton of fun to drive.

https://i.imgur.com/ogK6UWO.jpg

Here I was using the biggest cam CC had in the catalog. It was specifically made for ITB set ups, with a 114* LSA. Later I changed to the next smaller cam. I lost about 20hp and 20 ft/lbs. But I was turning faster lap times! I think it had better throttle response, and I was pulling out of the corners a little quicker. I also got better gas mileage on the street.

After racing for a few years, I decided "upgrade" to some Brodix heads.

https://i.imgur.com/akki39h.jpg

https://i.imgur.com/OYINwhl.jpg

https://i.imgur.com/t3qOkNS.jpg

Unfortunately, I didn't get the results I was after. The bigger valves and intake caused the intake air charge to slow down and become turbulent just before the intake valve. That's a bad thing.

https://i.imgur.com/46cAWWp.jpg


Moral of the story: Bigger is NOT always better. ;)

[Gordon Levy]

Bob, you really needed more cam and a bit of intake porting with those heads.

[skullandbones]

Asked a Comp Cam tech about the cam. He suggested a 35-872-13 lift @50 237/247 lift 0.632 LSA 112 but said it really needed to be 114 or 115 (custom grind). He also suggested short through hydrolic lifters; said it was more rpm friendly with less chance for floating. So now I have some hard data for that aspect which, to me, is the most complicated. I gave him the 408 CID so that is what I am leaning toward. It is the most popular stroker so there are more offerings. Also, thanks for suggestions.

Looks like a two phase project. I will install the 8 stack injection on the 302 just as is with gt40p heads and e303 cam. It will be fun to drive for a while. I can also take time to tune the new profile on my Stinger computer with Tuner Studio. When I make the change, the tune will be mostly done. Will have to update CID, head/ valve date, etc but will have a basic tune for starting and real time tuning. I will publish a video of the first start but it will be several months.

thank you,

WEK

[Gordon Levy]

Too much lift, you don't need anywhere near that.

[mike223]

Looks like a two phase project. I will install the 8 stack injection on the 302 just as is with gt40p heads and e303 cam.

First - you do realize that the 351w block and the 302 block require different intakes, right?

Seems a little excessive to buy another 8 stack intake to me, but whatever works...


I'm running a 35-770-8 solid roller cam (Comp Cams) with 393w / TF170 heads / 10.5:1 / Holley 750 - works well, good street manners - I might even consider the 771 cam (one step wilder).

But I would definitely go with a hydraulic roller cam if I were starting over - probably 35-426-8 or 35-427-8.

No problems with the solid roller - just the extra noise.


I have no idea how any of those cams would work with 8 stack, but very pleased with a 750 carb.

[Bob Cowan]

Too much lift, you don't need anywhere near that.

I agree. I'd look at something like .580-.590'ish.

[skullandbones]

Yeah, I do know the intake won't work. I did a trail fit just to see exactly how they were different. I knew from reading before but seeing it in real time shows you how changes in deck height for instance changes the whole architecture. I will use the 302 intake for a while and purchase a manifold for the 351 later when needed. They are app $350 right now. The interesting thing about the bigger picture is I have experienced a long runner Systemax induction, a medium length runner with my hand built plenum setup, and the new short runner ITB setup on the same engine. It's fun to see those variations in real life. I appreciate the info on cams. So a good starting point is LSA of 114 or 115 and a lift of around 0.55 . I am also thinking that 30 lb injectors will be needed instead of the 24s I am using on the 302 (maybe more).

[skullandbones]

I really do appreciate this forum for the input I get. The posters bring up some very interesting details and perspectives that round out your way of looking at a problem or potential project. On this 351 build, I think it made me focus better on some possibilities out of hundreds of choices you can make. So right now I probably will go with a rotating assembly with a real 4 inch piston (not 30 over) and a 4 inch stroke. This will give me a chance to go bigger if needed later with a possible CleVor build. But for now a 402 sounds like just what I need. I'm not superstitious but this falls right between the two favorite hot rod engines I ever had: 396 BBC and 409 BBC. It also gives me an added 100 cid, right cid for the new heads and induction, good stroker architecture, and the stroke will favor the type of driving for 80% of the time. So the only thing will be to choose that tricky cam. But the help I have gotten here will target that issue a little easier.

Thank you all,

WEK