I am considering how I should build my next SBC to replace my marginal goodwrench crate motor, and debating what bore/stroke combo to go with, factoring in cost/availability of parts, durability of a smallblock, and of course, wanting inches, cuz there's no replacement for that.

I'm trying to make about 400+ streetable hp, and I figure more or less inches can be used to offset how much cam I use, since I intend to keep the RPMs below 4500 for the street, but capable of maybe getting a safe 52-5500 at the track.

What kind of combo do you guys think would work best?

4.155x3.75 for 406? 4.125x.375 for a more standard possibly cheaper 400? Can I squeeze more inches out of a non-diesel smallblock safely?

EDIT: In http://www.popularhotrodding.com/enginemasters/articles/chevrolet/smallblock/0305em_mmouse/

some guy says "The engine I'm building is 400 ci to provide the maximum power potential in the small-block architecture. I have built small-blocks of larger cubic inches, but to go much bigger than 400 ci requires expensive custom parts and modifications to the block and other components, all of which I'm steering clear. That's not to say the Scat crank and rods aren't trick--they are--but they're also sitting on the shelves of many speed shops, ready to ship."

355 can do that,383 alot easier, 400hp is a piece of cake anymore, with stock GM blocks, I'd use Vortec heads unless you have some aftermarket heads you plan on using.

Especially with your self imposed rev limit, bigger would be better. It will just make things easier to make the power you want without having to spin the engine as far. Id build an internally balanced 406 inch engine with maybe around 9.75:1 compression....not much more is needed if that much, performer rpm(or airgap) intake, 750 vacuum secondary carb, any descent aftermarket head around 180-200cc typically(but the vortecs could work too as well as some other smaller heads like 170cc E tecs or performer rpm heads....ID rather the E tecs though for an edelbrock head), and one of Harolds voodoo 268 hydraulic camshafts. That should make for a streetable package that doesnt need to be run real high to make power, and it should make the power you want just fine.

As far as cranks and rods go, a lot of the stuff out there thats good enough to do the job is hardly more expensive than freshening stock stuff, so keep that in mind. If youve got a good stock crank, I might reuse it, but if you need a crankshaft, I wouldnt waste my time looking for a used stock one so that you can have it cleaned up. I beleive(but Im not positive) that Mike Lewis(wolfplace) deals scat stuff. He should be able to hook you up, and even without a hookup(if Im wrong and Mike doesnt deal scat), you can buy the scat 9000 series cast crankshafts from sallee chevrolet for 231 bucks. That aint so bad at all.

Connecting rods are the same deal. Id ditch the stock 400 rods for sure in favor of a 5.7 or 6 inch combo. You can get their 4340 forged I beam connecting rods for cheap as well. The price varys between about 245-290 bucks depending on what you are looking for.....and thats for a 4340 forged rod.

In the end, I wouldnt really call that stuff that I just mentioned "trick" myself. Its more like better than stock stuff at a real reasonable price but its not really anything too fancy. Just good parts. Talk to wolfplace. He should be able to help you out getting this stuff if you do need to do up a bottom end for the 406, and he will tell you for sure which route to go(as far as whether he would like 5.7 or 6 inch rods in your setup, which pistons and all that jazz). Good luck.

Here's my 357 combo, it makes a bit over 400hp at the crank, spins easily to 6500. Just a 350 +.040. I've got probably $3k in it, but if you had alot of the parts to start with you could build it for much less. My next iteration will have forged rotating assembly, and I'll get the heads ported and wind it to 7k.

www.69boo307.com/combo.html

I've gone a different route. Instead of the normal 350 block with 400 rotating assembly (383), I went with the 400 block with a 350 rotating assembly......377!! I went with 10.5:1 forged pistons, Pro Topline 200cc cast heads, single palne intake, .548/.560 solid cam, modified 750 AED/Holley.
All in all, I got $4,000 into the whole motor, and got around 525 horse out of it!!!
Brian

The shorter stroke motors can easily make 400 H.P. and clear a standard cam better.

Thanks for all the food for thought guys. To narrow things down, I'll probably go with a hydraulic roller with a lil under .50 lift that would spin to 5500 max and retain some low end so it can be streetable and deal with having to sip low quality california gas. Whatever I build will be bolted in front of a bow-tie overdrives level 2 2004R with 2800 stall and 3.42 posi. That's whats in the car already, so I'll build to match those specs, since I don't have much usable engine parts for this build yet, except for a 750 quadrajet and generic headers, which should be fine.

Since getting +1hp/cube isn't difficult and I don't wanna hit 6krpm, the sub-400inch is ruled out, but that forces more stroke, and I don't wanna push a block that hard, definatley using a cast crank and possibly some lightweight aluminum pistons. I'm still undecided about the merits of either a short stroke big bore, low piston speed or the reverse. What is the most I can bore out an SBC block to safely? At this point I'm still leaning towards the 406 along the lines of what greg described since it seems a little cheaper to build.

EDIT: Can anyone elaborate on the implications of using different rod lenghts?

What is the most I can bore out an SBC block to safely? At this point I'm still leaning towards the 406 along the lines of what greg described since it seems a little cheaper to build.

Considering your goals, I have to ask why you are pushing any limits at all?

The maximum amount a 400 can safely be bored out depends on the amount of core shift. This will have to be measured by the machine shop and blocks can vary tremendously in this area.

Rather than seeing how thin you can make the walls of a 400/406 and hope its okay, I respectfully submit you review the 383 once again.

Mine got some good stuff (including a solid roller) but I made more than your goal, too. I have no problem beleiving a 383 can easily be crafted to supercede your target power goals without having to concern yourself with thin walls, steam holes, or external balancing issues all 400/406s must account for in some form.

I built a 4-bolt truck 350 block with a Lunati matched crank/rod/piston/ring/bearing kit, which comes pre-balanced and matched. This sidesteps machining expenses for these procedures and the kit is internally balanced, allowing you to run the wider selection of balancers and flywheels/flexplates for your application.

The 350 block has plenty of wall thickness and I didn't have to drill anything for steam holes.

I chose out-of-the-box AFR 215 CNC heads to match my cam (larger than you'd prefer), but I'd bet 195s would be perfect for your smaller cam.

I chose a Performer RPM Air Gap, HVH spacer, and Demon RS 825 cfm (but the venturi sleeves can be changed to adjust carb cfm potential to suit the engine), MSD6AL, Milodon pan/pump.

I had the AFR chambers, valves, and ports coated by Calico.

On 87-octane my 383 made 500 ft.lbs (ok, 499..) and 545 peak hp. The torque curve was flat and the power started coming on hard by 3,000. But, that's mostly the cam/port relationship and your results will vary.

My point is a damn good 383 can be crafted to make more than 400 reliable horses on 87-octane without any of the oddities of the 400/406. You're already pushing limits on bore size, and you shouldn't have to worry about any such thing.

Look back at 383s...I think they're real popular for good reason!

SP~!

Why would you only want 5200-5500 rpm? RPM makes horsepower, so I'd go as high as you can. A hydraulic cam will safely go to 6000 rpm with the right springs, and so you'd have a peak hp at about 5500 rpm, and with big inches you'd still make gobs of torque. Tow truck motors are for tow trucks, make something that doesnt run like a 3 legged pig past 5000.

I know hydraulic cams can go past 6000 rpms and beyond, but I wanna keep the power way below there so I can have this motor be uber-streetable and have nice, effortless low-end stoplight-to-stoplight action which it will see plenty of. (with the uncooperatively loose 2800 stall converter) This will be primarily a street driven engine with occasional track time, and need to have usable torque below 2000 rpms. I don't want this one to drive like my 6200rpm 450hp 363 olds with 236/244 and .56 lift, which isn't that street friendly.

I know the 383 is popular for good reason, but that makes it passe at the same time. The 406 shouldn't be too stressful for a little mouse, and means I can run 5 degrees? 7 degrees? of less duration and have how much more low end torque? Since the 406 looks like the way to go for me, can anyone point me to some places where I can buy balanced rotating assemblies? Summit and Jegs is not satisfactory. Where would you guys recommend for a new 406 block too, since my current goodwrench block will not be reused, and since so many companies make SBC gen-I short blocks these days?

Scotch: Since I am new to SBC engines, are you suggesting the 406 is too much bore to be safe and that usually requires special tricks to build?

I have heard nothing but good marks for the RPM airgap manifold, and MSD ignition is a foregone choice, but what (aluminum) heads and cam will be the decisive choices. I'll probably go with a level 2 quadrajet for good part-throttle street use, since I don't think it will be a bottleneck at 750 or even 800 cfm.

Remember I'm only trying to make a lil more than 400hp with about 400 inches and as little cam as possible, and trying to do it cheaply with as little machine work as necessary.

Scotch: Since I am new to SBC engines, are you suggesting the 406 is too much bore to be safe and that usually requires special tricks to build?

No- Not at all. But, there are some quirks to the 400 which no other traditional small-blocks share.

Like the steam holes between the siamesed bores on the center cylinders. This means the middle four cylinders often run warner than the outer four cylinders. Also, your cylinder heads must get these steam holes drilled into them for adequate cooling.

400 blocks have a big bore, which means they can have thinner cylinder walls (especially if there's any significant core shift). As I mentioned, this MUST be checked before getting into overbores beyond .030. I would sonic check any 400 block I wanted to go .040 or more overbore.

400 reciprocating assemblies are externally balanced, which I mentioned earlier as well.

To sidestep all of these quirks, I chose to go 383 with the Lunati internally-balanced reciproacting assembly I mentioned in my previous post. I seriously considered going the 406 route, but knowing i'd be road racing this engine, and also hitting it with spray at the drags, I wanted more than adequate cooling, the ability to shop parts without balance issues (a T-56 was part of the plan from the start), and the beefcake I like in the non-siamese cylinders.

That, and I got a swingin' deal on the 350 4-bolt bare block when my neighbor sold his Camaro and got a new Mustang...

Scotch~!

Great thread. As I'm going the 400 block route, I'll add:

Wolfplace can give your a nice internal balanced crank/rod/piston setup (that I will use).

Steam holes are straight forward to do.

Thanks for the extra info. When drilling steam holes on the cylinder heads on a 406 build, are there any particular castings I should avoid or that are better suited to this displacement? Considering cost, I'm looking towards some aluminum trick flow or edelbrock heads, but I know that there are dozens of companies that make heads for small block chevs, unlike oldsmobile, which is the performance background I'm coming from.

As for siamesed cylinder walls, that is a term I've heard before, as in the olds 403, but I don't fully comprehend what this means besides thinner cylinder walls. Anyone got some pics of this?

As for the block, I'll probably get a brand new one and maybe an assembled short block if I can find it, but if I come across any good deals or used ones, can a regular 350 block be bored to acheive 406cid? As for stroking to 3.75, the bottom of the cylinders will just have to be notched a bit, and nothing more right?

Rick: Is wolfplace a member on this board, or a parts retailer? I'm starting to get enough data to put together a parts list now. How much do you think this 406 project can be done for? CHELKAMINO built his 525 horse 377 for $4000 dollars, so should I be able to do what I want for less?

A 400's siamesed cylinders just means the inner cylinders cylinderwalls are together, (i.e., party-wall like), instead of being 100 percent separated!

Like an "8" instead of two "OO"s like a 350 and all the other blocks.

pdq67

If you're going with a brand new aftermarket block, then don't even worry yourself with the thin walls that plague the GM blocks. The aftermarket blocks are much thicker (and concequently much heavier) and have an upgraded oiling configuration and all kinds of little upgrades. Not to mention that core shift, from what I've heard, isn't a big deal on the Aftermarket blocks.

Only drawback is the price...

Yes, wolfplace is a member here and that's his handle.

That description makes it pretty clear, thanks pdq.

I looked up a few places on brand new 400 blocks and I was suprised on how much more it costs, so I'll be looking at those old school blocks a little harder now.

At least I know what block/rotating assembly I will build and what I want out of it, though, so now I just need to pick the right cam. I'll probably buy the cam first to "commit" myself to the build.

I try ta help, BUT I gotta stay away from the BS section's on the "Boards" b/c I tend ta get too riled up!!

He, He!!

pdq67

Will a 2500-3000 stall for a 350 fit TH200 metric? the splines look the same!