396sb vs. 406sb

This question involves two small blocks. I understand that you can get great torque and power from a 406ci engine. I also understand that you can take a 350, stroke it with a 3.85" crank and get a 396. Correct? So how would the power curve and numbers compare on these two if built similar? Also how does a 383 compare to the 396? Anyone have advice or tips on building a 396 ci small block?

How much power are you looking to make? The 406's make pretty good power, we have done a decent amount of these. If not the 383's aren't bad either. You can get one of these pretty reasonable depending on what parts you want in them. Give us a call and we would be more than happy to help!

Thanks

My 406 is approx. 475 horse according to the engine builder. It is still on the stand in the basement so I can't verify that with dyno #'s. It is naturally aspirated and will run on pump gas. I bought it for a song off a guy from work that needed the money. He had about $4K in it minus heads and intake. I bought it for $1500 and bought a Edlebrock performer RPM aluminum head and performer RPM intake package for $800 after the fact. Like I said, I asked the engine builder what it would do with this head and intake package, and he assured me of at least 475 horse. Not bad with some relatively wussy heads. I am not sure of the cam specs on it, I have it all on a sheet somewhere, but I am not sure where it is. All I know is that it is a comp cams high energy cam. It has dished JE pistons in it, and with a 64cc Edlebrock head, that puts me at about 10.5-10.75:1 compression. If you really want to go fast, stroke a 406 :bow:

FWIW,

4.030 bore, 3.75 stroke = 383
4.030 bore, 3.875 stroke = 396
4.155 bore, 3.75 stroke = 406

The 396 has more stroke and a relatively small bore where the 406 has slightly less stroke but a larger bore. I'd definitely go the 406 route. It will have plenty of torque with the "smaller" 3.75 stroke, but it will breathe better with less valve shrouding than the smaller 4.030 bore 396.

As for stroking the 406, I wouldn't do it with a stock block. I went that route, but I went with a Dart block.

I see, i was off a little on the stroke of the 396. I was just curious on how a 396 or 383 would compare to the 406. I have a 350 thats .040 over, with some nice ported dart heads, but I want more torque and streetability so why not stroke it right? So my options are the 383 or a 396 small block, which I thought would be cool since my 68 Nova SS was an original 396 BB. I don't have the BB obviously.
I looking to make at least 450 hp, and 500 lb ft of torque. Pump gas friendly, running 4.10 gears or smaller, 4-speed car. The heads are Dart iron eagle 2.02/1.60, 64cc, 200cc runners, comp. bowl, valve and port work done. I figured that with the 200cc runners it would keep velocity up for torque :D , and add a hyd. roller it shouldn't be hard to reach my goals. Any advice on companies to look at for rotating assemblies would be great, also any advantages to the 396 over a 383? Really?

Go with the 406.

Much easier to make better hp/tq numbers with the 4.125+ bore blocks. More room for larger valves.

A respectable and very streetable 406 should make ~550hp and 500lbs-ft of torque without breaking a sweat. Need a good cylinder head to get there.

-Mindgame

The extra bore of the 400 block would be good, but I think you'll find the torque you want with the stroker crank... and if you're going to stroke the motor might aswell go with the biggest displacement possible :D

Yeah, I agree on going the biggest possible. I don't plan on spending the extra on a 400, so I'm just going to stroke the 350 I have and save some dough. I guess all thats left is how will the power be different between a 396 and a 383? Whats the advantages and disadvantages of a hyd. roller and a solid roller is a strip, but mostly street application?

Nova, here are some 383 combinations to check out. If nothing else, it gives food for thought.

383 combinations, cam specs and peak numbers (http://www.thesuccesssolution.com/site/index.asp?DL=5488&page=97445)

Wow, I sure hope that I can get better numbers with my Dart heads. Or I might as well finish my BB. Heck, HP wise my 357ci. is running close to those numbers with my heads and a comp Xtreme Energy XE284. :confused: Also what is the cost involed in machining the block for stroker cranks (typical 383 cost)? In a 396 (3.875" stroke) Do the rods need to be altered to avoid camshaft interferance? Would a small base circle cam do the trick?

The differences between power (383 vs 396) are very small within street applications. The power potential is there with the 383, not to mention, the 383 gets more off-the-shelf piston choices than the 396 and a small bit more cam clearance. The 383 in my 4th gen makes ~570hp at the rear wheels normally aspirated. There's also enough torque to smoke a set of street radial tires at just about any engine speed from 2000rpm up. May setup is based around a GM 15º race cylinder head, but my point is only made to give an idea on "potential".
As far as putting everything together... a small base circle cam will be needed with whichever choice you make. The amount of block clearancing will vary depending on the rod-make you decide to use. Some need more clearance than others. A call to your engine builder will get you an exact price as stroker clearancing is common practice.

All said and done, the 406 will still make more hp and torque. Especially when you get into large valve heads (2.05+) on standard 23º valve angles. The smaller 4.0 bore motors run into bore shrouding problems with these heads. So, it all just depends on your end goal. I would have much rather made the power I'm making through a 406 (4.155 bore) block than the small-bore LT1 block. Would have been that much more streetable.

-Mindgame

What kind of streetability and power numbers could I expect with the dart heads listed above and a 230 duration, 550 lift solid roller. What would be the differences between a hyd. roller and a solid roller in the application?

What kind of streetability and power numbers could I expect with the dart heads listed above and a 230 duration, 550 lift solid roller. What would be the differences between a hyd. roller and a solid roller in the application?

Nothing wrong with that choice, although I'd probably opt for something more akin to 236/240 .570/.570 110º lsa. That cam is just an example (not a specific grind) but it'd be very streetable in a 383. Power will meet or exceed your goal. I'd say numbers could be anywhere from 460hp/500lbs-ft to 520/530. Just depends on the match of the setup. If you want to go the torque route, stay with an intake like the Edelbrock air-gap RPM. If you'd like to turn a few more rpm and soften the bottom end a little, use the Vic Jr, Super Vic, etc..
The dual plane could make nice use of a larger carb (800-850cfm) where as the single plane may work best with a 750 double-pump or vac. secondary. You can find power by going larger using one of the aftermarket carbs like the BG Demon or Holley HP but you'll need to iron things out (tuning) before you really see the gains. These carbs offer a good deal of fine tuning to the metering circuit, so it's not difficult to make them perform well if you know what you're doing. They aren't bad out of the box either.

Sounds like you're well on the way to meeting your goal though.

Good luck.

-Mindgame

Yes I deffinetly am going for the torque. I have heard great things about the performer RPM air-gap. What kind of gears would go good with a cam of that size Mindgame? Its a Muncie 4-speed car, 28" tire. I want to be able to drive it on the freeway (not often) with no heating problems. I was thinking 3.73's or 3.90's?
The cam that Comp reccamended was the XR294HR or the XR274R.
Specs are:

XR294HR: 2800-6100 Hydraulic Roller
242/248 dur.
540/562 lift

XR274R: 2200-6200 Solid Roller
236/242 dur.
564/570 lift

How do those sound? How much more power would the solid make? Would the engine be able to handle some freeway trips as well as around town cruising and bruising? Comp said that I would only need 9:1 or 9.5:1 comp. and that they are both easy on parts.

Yes I deffinetly am going for the torque. I have heard great things about the performer RPM air-gap. What kind of gears would go good with a cam of that size Mindgame? Its a Muncie 4-speed car, 28" tire. I want to be able to drive it on the freeway (not often) with no heating problems. I was thinking 3.73's or 3.90's?
The cam that Comp reccamended was the XR294HR or the XR274R.
Specs are:

XR294HR: 2800-6100 Hydraulic Roller
242/248 dur.
540/562 lift

XR274R: 2200-6200 Solid Roller
236/242 dur.
564/570 lift

How do those sound? How much more power would the solid make? Would the engine be able to handle some freeway trips as well as around town cruising and bruising? Comp said that I would only need 9:1 or 9.5:1 comp. and that they are both easy on parts.

9.1-9.5:1?

9.5:1 static using the XR274R cam puts you at a dynamic compression ratio of ~7.8:1. The cylinder pressure at low engine speeds is going to be too low for snappy acceleration/response. A cam of that size would be much more responsive with a static compression of ~10.8:1, which puts the dynamic at ~8.9:1.
Believe me, you want more compression than Comp is recommending for that camshaft. As for "solid roller". At this level, I'd pass and go for a hydraulic. If you wanted a solid roller, I'd use a cam more like the XR294 in specifications, but I don't see the solid as a necessity considering your goals.

4-speed car, I'd go with the 3.90's.

-Mindgame

You don't have any pump gas issues with a dynamic of 8.9:1? If not, what's the secret?

I can't say I've ever tried to put one together that high, being a hobbyist, and all.

You don't have any pump gas issues with a dynamic of 8.9:1? If not, what's the secret?

I can't say I've ever tried to put one together that high, being a hobbyist, and all.

No secrets besides the typical stuff.... no sharp edges, maybe a step or two colder spark plug, tight quench, efficient cooling system & lower temp thermostat, etc..

I'm running right at 9.0:1 in my 383 LT1, ~575rwhp NA. Runs almost 10-flat 1/4 miles on a street suspension setup with no signs of any detonation. My buddy's Nova is a 421ci small block setup for 8.8:1 dynamic, this engine is making 673hp at the flywheel. Been together for almost 1 year now and no signs of detonation there either.

Most of the really strong engines I'm seeing these days are running between 8.5-9.0:1 dynamic compression. I think alot of the experimentation has spawned from events like Popular Hot Rodding's Engine Masters Challenge. Limitations are based around pump gas and getting the most avg torque and horsepower. The guys who've been in the top 5-10 in each round (small blocks and big blocks) all had setups with dynamic compression in the 8.5-9.0:1 range. No coincidence there IMO.

One thing about running larger camshafts that people always seem to misss is the change in dynamic compression. Magazines always run tests where they'll swap cams on the same motor, then make comments like "See, the larger cam only hurt the lowend and the liow-midrange torque suffered". Well sure... if you knock the dynamic compression to 8.0:1 or lower, the things gonna be soggy on the bottom. No big secret there, but people miss the details. Get the dynamic comp up and you regain alot of that low-midrange torque and shift everything higher rpm-wise for hp/torque.

I'm just a hobbyist myself, but I've spent enough money for services that I could pick the brains of some really good engine builders. All seem to concur with this dynamic comp range for pump gas street engines. The tuning and all the little details need attention but once it's setup correctly, the engine will need no more maintenance than any other high performance mill.

-Mindgame

Do you think the reverse-flow of the LT1 is a big factor in allowing the high DCR?

I'm getting ready to put together a 383 (Gen I SBC), and I was looking at hitting right around 8.5:1 DCR. I intended to run somewhere around 10.5:1, and about 22x* .050 on the cam. I'm just thinking I might be on the hairy edge of getting this thing to cooperate, using a carb and all. With the six-speed, I want all the low end I can get, and I have no real interest in spending the money to rev past 6200-6300.

Just curious. If I screw it up, that'll just force me to get off my wallet, trade out the old 63cc Twisted Wedge heads (first design) for some new 68-72cc AFRs.:D

Do you think the reverse-flow of the LT1 is a big factor in allowing the high DCR?

The reverse cooling of the LT1 definitely helps things Todd. You're right.

The LT1 has that to it's advantage. One disadvantage it has is in being fuel injected and having a dry manifold. The intake is always higher in temperature than a carb intake because it can't take advantage of latent heat of vaporization in the plenum and port entries. So, those gains from reverse cooling are slightly offset by higher inlet temperatures.

Now, you can improve the cooling of a 1st gen sbc easily enough. Here's an example I found with a quick search to give you a general idea. Cooling System Mods (http://www.grapeaperacing.com/GrapeApeRacing/camaro/cooling.cfm)

I've done this on a few of my own engines. Routing coolant to the area between the two exhaust valves is always a good idea on sbc's because that's where they typically get the hottest. Using a Brodix intake (or similar) that moves water from front to back also helps.

I'm getting ready to put together a 383 (Gen I SBC), and I was looking at hitting right around 8.5:1 DCR. I intended to run somewhere around 10.5:1, and about 22x* .050 on the cam. I'm just thinking I might be on the hairy edge of getting this thing to cooperate, using a carb and all. With the six-speed, I want all the low end I can get, and I have no real interest in spending the money to rev past 6200-6300.

Just curious. If I screw it up, that'll just force me to get off my wallet, trade out the old 63cc Twisted Wedge heads (first design) for some new 68-72cc AFRs.:D

Sounds like a good plan to me. Just calculate your compression carefully and tune from rich to lean. If you can get some time on a chassis dyno with a wideband O2 sensor take it. Then fine tune the combination at the track.

Good luck.

-Mindgame

My brother is putting a 396sb in his 73 Camaro. Dart Iron Eagle 215cc heads, Herbert .567/.567 hyd. roller cam, Victor jr, 750 holley carb, TRW pistons (modified).. shortblock is done.. next week we put the motor together..

-Alex

Mindgame how do you figure static to dynamic compression? and would you give a clear example.

i say go the 406 route... as i did. the #'s below are 2 years old with an old "emissions friendly" setup. after emissions and i knew how much i could go, i changed out the cam and went to bigger injectors, ect.. and i (lowballing) expect 450RWHP and 500RWTQ (i was worried about emissions and had a really small cam in when i got these #'s) with the new setup.