[techinspector1]

Originally Posted by LS-57

the rod length generates torque and horsepower and that was my point.

Oops, time to take you back to school.....
Please read this tutorial written by Ron Iskenderian, son of Ed Iskenderian, the famous "Camfather"....

"Tech Tip - 2005
Rod Lengths/Ratios: Much ado about almost nothing.

Why do people change connecting rod lengths or alter their rod length to stroke ratios? I know why, they think they are changing them. They expect to gain (usually based upon the hype of some magazine article or the sales pitch of someone in the parts business) Torque or Horsepower here or there in rather significant "chunks". Well, they will experience some gains and losses here or there in torque and or H.P., but unfortunately these "chunks" everyone talks about are more like "chips".

To hear the hype about running a longer Rod and making more Torque @ low to mid RPM or mid to high RPM (yes, it is, believe it or not actually pitched both ways) you'd think that there must be a tremendous potential for gain, otherwise, why would anyone even bother? Good question. Let's begin with the basics. The manufacture's (Chevy, Ford, Chrysler etc.) employ automotive engineers and designers to do their best (especially today) in creating engine packages that are both powerful and efficient. They, of course, must also consider longevity, for what good would come from designing an engine with say, 5% more power at a price of one half the life factor? Obviously none. You usually don't get something for nothing - everything usually has its price. For example: I can design a cam with tremendous high RPM/H.P. potential, but it would be silly of me (not to mention the height of arrogance) to criticize the engineer who designed the stock camshaft for this engine when I know how poorly this cam would perform at the lower operating RPM range in which this engineer was concerned as his design objective!

Yet, I read of and hear about people who do this all the time with rod lengths. They actually speak of the automotive engine designer responsible for running "such a short rod" as a "stupid SOB." Well, folks I am here to tell you that those who spew such garbage should be ashamed of themselves - and not just because the original designer had different design criteria and objectives. I may shock some of you, but in your wildest dreams you are never going to achieve the level of power increase by changing your connecting rod lengths that you would, say, in increasing compression ratio, cam duration or cylinder head flow capacity. To illustrate my point, take a look at the chart below. I have illustrated the crank angles and relative piston positions of today's most popular racing engine, the 3.48" stroke small block 350 V8 Chevy in standard 5.7", 6.00", 6.125" and 6.250" long rod lengths in 5 degree increments. Notice the infinitesimal change in piston position for a given crank angle with the 4 different length rods. Not much here folks, but "oh, there must be a big difference in piston velocity, right?" Wrong! Again it's a marginal difference (check the source yourself - its performance calculator).

To hear all this hype about rod lengths I'm sure you were prepared for a nice 30, 40, or 50 HP increase, weren't you? Well its more like a 5-7 HP increase at best, and guess what? It comes at a price. The longer the rod, the closer your wrist pin boss will be to your ring lands. In extreme situations, 6.125" & 6.250" lengths for example, both ring and piston life are affected. The rings get a double whammy affect. First, with the pin boss crowding the rings, the normally designed space between the lands must be reduced to accommodate the higher wrist pin boss. Second, the rings wobble more and lose the seal of their fine edge as the piston rocks. A longer Rod influences the piston to dwell a bit longer at TDC than a shorter rod would and conversely, to dwell somewhat less at BDC. This is another area where people often get the information backwards.

In fact, this may surprise you, but I know of a gentleman who runs a 5.5" Rod in a 350 Small Block Chevy who makes more horsepower (we're talking top end here) than he would with a longer rod. Why? Because with a longer dwell time at BDC the short rod will actually allow you a slightly later intake closing point (about 1 or 2 degrees) in terms of crank angle, with the same piston rise in the cylinder. So in terms of the engines sensitivity to "reversion" with the shorter rod lengths you can run about 2-4 degrees more duration (1-2 degrees on both the opening & closing sides) without suffering this adverse affect! So much for the belief that longer rod's always enhance top end power!

Now to the subject of rod to stroke ratios. People are always looking for the "magic number" here - as if like Pythagoras they could possibly discover a mathematical relationship which would secure them a place in history. Rod to stroke ratios are for the most part the naturally occurring result of other engine design criteria. In other-words, much like with ignition timing (spark advance), they are what they are. In regards to the latter, the actual number is not as important as finding the right point for a given engine. Why worry for example that a Chrysler "hemi" needs less spark advance than a Chevrolet "wedge" combustion chamber? The number in and of itself is not important and it is much the same with rod to stroke ratios. Unless you want to completely redesign the engine (including your block deck height etc.) leave your rod lengths alone. Let's not forget after all, most of us are not racing at the Indy 500 but rather are hot rodding stock blocks.

Only professional engine builders who have exhausted every other possible avenue of performance should ever consider a rod length change and even they should exercise care so as not to get caught up in the hype."

http://www.iskycams.com/ART/techinfo/ncrank1.pdf

[devarsity61]

I didn't mean to start everything about the 406 I am a beginner Im looking for some help with my build. I just put that out there because I have people giving me advise in my town. I am just want a powerful street engine. Im looking for any help i can get.

[cobalt327]

Originally Posted by LS-57

To compare 406 to a 383 shows a lack of understanding of what a 406 is. A 383 starts as a 350sbc and needs revs to produce power. It has a sharp torque & hp curve where as a 406 stroker starts as a 400sbc and produces horsepower and torque just off idle with a relatively flat curve on both. Pretty hard to compare those don't you think?

I think you're a google guru who can't even get the basics right. I allowed you the benefit of the doubt by saying you probably had mistakenly referred to the 406 when in fact you meant the 383- why else would you say Lingenfelter "built" the first 406 in the freaking 80's? All a 406 SBC is, is a 0.030" over BORE 400, nothing to do w/a stroker unless you were talking about some tiny offset grind deal, as was already mentioned.

Is a 406 stroker that unheard of on this forum? Looks like some of you really need to do some homework on a particular engine before you make a comment.

Look- do not pretend to school ANYONE on this board. Your lack of the basics show you to be a noob of the first order who should take the advice you so arrogantly say others need. The 400 SBC is not a freaking stroker, noob. It was a regular production engine- period. It never used 5.7" 350 rods from the factory- NEVER.

Let's all play nice & learn from each other because isn't that what this forum is for?

Until YOU learn some basics, shut the hell up and like I said earlier- take your own advice.

Keep it up and you WILL get served.

[cobalt327]

Originally Posted by devarsity61

I didn't mean to start everything about the 406 I am a beginner Im looking for some help with my build. I just put that out there because I have people giving me advise in my town. I am just want a powerful street engine. Im looking for any help i can get.

Guy, ask away. But you'd be doing yourself a favor by reading up on the subject so you can ask intelligent questions as opposed to open ended queries that would basically take a book to answer. Not being harsh- just telling you what I would tell a friend.

[chevy302builder18]

i agree with tech on the piston dwelling and stuff like that... Very intresting dynamics, I have a qeustion I cant find short 5.5 inch aftermarket rod lengths for a 400 anymore, except H beams, and the only thing summits got cheap is a 5.7 rod. Will this mean ill have to build mine with 5.7 inch rod?

[cobalt327]

Originally Posted by chevy302builder18

i agree with tech on the piston dwelling and stuff like that... Very intresting dynamics, I have a qeustion I cant find short 5.5 inch aftermarket rod lengths for a 400 anymore, except H beams, and the only thing summits got cheap is a 5.7 rod. Will this mean ill have to build mine with 5.7 inch rod?

The 5.7 rod is what you WANT to use, if you want to have a long-lived engine that is cost effecient. The only possible reason to use a one-off rod length like 5.5", that requires custom pistons or extra work on some sort of existing piston to make them work in a 400 SBC, is if it's a no-holds-barred race piece where there is little or no concern for the thrust loading of the cylinder walls, etc.

[ChevelleSS_LS6]

Originally Posted by devarsity61

I didn't mean to start everything about the 406 I am a beginner Im looking for some help with my build. I just put that out there because I have people giving me advise in my town. I am just want a powerful street engine. Im looking for any help i can get.

I assume you already have a 400ci block. If it's good to run in stock bore and stroke, I'd run it like that. 6 cubic inches isn't much when you already have 400.

I would use a cam designed to optimize low end or midrange torque (if you have a heavier car like an Impala or a vintage pickup, go with a torquier cam, if this is lighter like a Camaro or Nova, then you can run with something more 'midrange'). I suggest this cam- I do believe it will work with a stock torque converter if you have an automatic trans. CLICK HERE

Top it off with headers (smaller tubes help with torque, larger tubes are better for higher rpm) and a dual plane intake. Make sure you have 3.55 or 3.73 gears out back for good acceleration as well. Lots of older cars may have 3.23 gears or something that's great for highway but weak on acceleration. 4.10s are great for acceleration but are not as highway friendly.

It all depends on the build. Does the block need bored? Then you can say you have a 406. Is the original crank bad? You may be able to get it offset ground or even order a stroker kit. In my book, if you want a powerful street engine, save the money on the stroker and put the money into a good set of cylinder heads.

[cobalt327]

Hopefully ericnova72 will be along and add his 2¢ worth- his advice is worth at least a nickel!

I owe the board and LS-57 an apology. While the basic content may be valid the way it was presented leaves a LOT to be desired. Not as an excuse, but as soon as I read those posts on the "406 stroker", and how non facts were presented as irrefutable facts, another member came immediately to mind- and from that point it was on. This other piece of work states his thoughts/opinions as if they were a fact, seemingly w/o having done even a cursory search to verify a statement before posting it as a fact. Not even a "in my opinion" or " I believe this to be so", etc. and often in a condescending manner if he's called on them

I'm relatively sure there must have been a misunderstanding of some sort that set the whole thing into motion. But in any event, hopefully this will soon be behind us and he and I can get on w/other pursuits more in keeping w/the forum in general.

Regards, Mark

[LS-57]

Apology accepted Mark, no hard feelings.
To the others, I took it for granted that what anyone says is an opinion hence I provided 3 backups to my findings and experiences with 400 sbc’s.
Maybe more of you should read with an open mind before jumping to conclusions. 2 days after the original poster asked the question and re-asked the question, I was the only one giving suggestions while the fireworks were on, finally ChevelleSS LS6 had some positive input to the original poster so thank you.

No back to our regular programming

The post is called MAX HORSEPOWER IN A SBC 400. and here is the statement and question. -

Originally Posted by devarsity61

ok I have a good 400 block that is ready to have machine work done. I also have some vortec heads that need to be worked. what are some ideas for the block and heads. I would like to stroke the 400 to a 406 what do u think

So let’s start from the beginning shall we? Reading the post it says “…..I have a good 400 block that is ready to have machine work done. I also have some vortec heads that need to be worked …...”. I took this as if he wanted to use an original block & heads and that they are ready to be machined, sorry I can’t think of any other way to take that.
If he is going to machine it, I’d recommend machining it to a 406. Not because 6 cubes produce a lot of power but rather the cylinder walls will most likely need machining (it is what the original poster said) so it would be a logical and cost effective step. I never said stroke it to 406, that was the original poster, who by the way is a self admitted beginner and is looking for advice from “the pros”. Give him a break for not knowing every term correctly.
He didn’t mention supercharging or turbo charging so my opinion and experiences with the 400sbc tell me that if it is ready to be machined and he is looking for max hp the way the title of the thread says, machining it to 406 and using 6” rods is the way to go. Your opinion may differ & that is ok. I am not a world renowned engine builder but I do know these motors well.

I’m interested as I know the original poster is as well to hear from all the wise critics that have shared there opinions, what is your opinion on the question at hand? Remember, this guy is a beginner. He wants to use an existing block & heads so he most likely will be on some sort of a budget. Tell us how you would make max hp in a 400sbc knowing he wants to use a factory block & heads? Provide proof that your opinion is a good one, not just an opinion.

[techinspector1]

Originally Posted by LS-57

Tell us how you would make max hp in a 400sbc knowing he wants to use a factory block & heads?

I would advise against max hp in favor of building for max torque in the 3,500 rpm range. L31 heads on a 406 will not lend themselves to high hp, so I would use them where they fit best, low rpm torque. I'd use Keith Black hypers, #KB168-030, hung on Scat Pro Stock 5.7" rods. These rods are clearanced for the cam right out of the box. Minimum clearancing may be necessary at the pan rail for the big end of the rods.
http://www.summitracing.com/parts/SCA-25700P/
6.0 rods get up into the oil ring land and I do not advise more complexity and more things to go wrong than you need in an engine build like this, particularly for a beginner. With nominal +/- 66cc heads (production heads usually pour larger than published data), these pistons, with a 22cc D-cup will produce 9.6:1 static compression ratio. An added benefit is the tall 1.433" compression height, meaning less block deck to cut off to reach a target squish of 0.035" to 0.045".
http://www.kb-silvolite.com/kb_car/p...hp?action=comp

Machining operations to the block, besides the boring and honing to +0.030 oversize, will include align honing the main bearing bores and cutting the block decks to square and to the proper block deck height to work with the piston deck height and gasket thickness to set the squish. Stock block deck height is +/- 9.025". The height of your stack of parts will be 1.875" for the crank throw radius, 5.700" for the connecting rod center to center and 1.433" for the piston compression height, for a total of 9.008". If we use a gasket thickness of 0.039"/0.040", then we will have to cut the block decks 0.017" to reach a zero deck. This will put the squish at 0.039" or 0.040", depending on the head gasket used. Decking the block will also insure that the block decks on all four corners of the block are the same distance from the main bearing centerline, meaning that static compression ratio will be closer to equal across all cylinders and will also contribute to the heads and intake manifold lining up and sealing the way they're supposed to. Thinner shim head gaskets used to be available for the 400, but not any longer. Some fellows have used 350 shims and drilled them for steam holes, but the bore of the gasket is iffy with the larger 400 bore. If you get any of that thin shim out into the cylinder/chamber at all and it glows hot, it could be a potential trouble spot for pre-ignition/detonation. Better to use a composition gasket that is engineered for the purpose and cut the decks accordingly. Speaking of steam holes, the heads will have to be drilled for them. Here's the tutorial....
http://www.gregsengine.com/convertin...ds-to-400.html

I'm going to waver from my usual roller tappet song and dance here and suggest a low-cost hydraulic flat tappet cam because we're going to use the stock L31 valve springs and retainers. Our rpm limit with this motor will be 5000, so we don't need to do any changes to the heads except maybe replacing the seals, unless of course if you want to pony up 60 bucks for fresh springs. Chevrolet says if you want to keep some safety margin (total of 0.050" between the 5 coils), then you should limit valve lift to 0.430". We can move into the margin a little with this low rpm motor and use a cam with 0.450" lift if we need to. I would advise against the use of an extreme energy type cam and also against the use of rockers in excess of 1.5:1 ratio in this build.

Crane has a cam that uses easy ramps and will fall right into the static compression ratio range we will use in this motor. #10017 has an operating range of 1800-5400. Here's the 100172 kit which includes lifters. Always buy your lifters with the camshaft....that way you know they were produced by the camshaft grinder, not some fosdick Chinese outfit....
http://www.amazon.com/Crane-100172-E.../dp/B000CIRW8I
Crane's description says the cam needs a 2500 converter, but with the amount of torque we're gonna produce down low, I'd be thinkin' stock converter and a 3.50 gear. The lobe separation angle of 106 degrees will give us the bottom end bias we need and the 0.450" theoretical lift will work with our stock springs and retainers. Be sure to use feeler gauges between the spring coils at full valve lift to insure that the springs don't stack solid. In theory, they shouldn't, but theory doesn't always agree with reality. Use 16-18 degrees of ignition lead at the crank with an additional amount at the weights to bring the total initial and centrifugal to 34 degrees. That's all you need with these heads. You need more at the crank than you would with a stock cam though, for the motor to idle properly. We need to bring the idle down for use with a stock converter so we don't have to stand on the brake pedal at stoplights.

OK, we have a long block. Now, let's bolt on an Edelbrock Performer RPM intake manifold and top it off with a rebuilt Edelbrock Thunder series AVS 650 CFM, manual choke carburetor #1805. Also get the Edelbrock choke cable #8013.
http://www.edelbrock.com/automotive_.../thunder.shtml
Mount a 14" x 4" air filter on top. Stack two 14 x 2's if you can't find a 4" thick element. This motor needs to breathe. Speaking of that, bolt on a pair of equal-length, long-tube 1 3/4" headers and fashion either an X or an H pipe right after the collectors. Mufflers of your choice, but run the pipes to the rear of the car. Nothing is more "trailer park" than terminating the pipes under the car .

RPM HP TQ
1500 122 426
2000 174 457
2500 217 457
3000 268 470
3500 315 475
4000 354 465
4500 380 441
5000 373 392
5500 326 311
There you have it boys and girls, a tire-shredding motor with a "flat-as-a-table" torque curve and a cam that will have a slightly rough idle so the OP can pose cool down at the Sonic Drive-In.

The OP should read this tutorial over as many times as it takes to make good sense of it and understand completely what it says......
http://www.crankshaftcoalition.com/w...ips_and_tricks

[nofearengineer]

I like it, Tech!!!

Look at that flat torque curve!

It might not have the peak numbers, but that thing will pull hard.

And be super streetable, to boot.

[68NovaSS]

Originally Posted by LS-57

I never said stroke it to 406...

To compare 406 to a 383 shows a lack of understanding of what a 406 is.

Is a 406 stroker that unheard of on this forum? Looks like some of you really need to do some homework on a particular engine before you make a comment.

What changed the tone of the thread was reference to the "Stroker 406", suggesting Lingenfelter was the first to "build" a 406 (first to bore a 400 .030?), the blanket statement regarding 383 vs. 400 power characteristics, and the connecting rod length effect on torque statement, all of which were presented as a matter of fact with attitude, and all from out in left field. Nobody that I can see accused anyone of suggesting he stroke it.

BTW, I enjoyed viewing your website, and small world, we share a common bond with our cars being featured on My Classic Car with Dennis Cage, for me when he visited Anchorage during our (Midnight Sun Street Rod Association) annual show 'n shine. Unfortunately, I hadn't shot color on it yet.

[ChevelleSS_LS6]

Originally Posted by techinspector1

I would advise against max hp in favor of building for max torque in the 3,500 rpm range...

... I would advise against the use of an extreme energy type cam and also against the use of rockers in excess of 1.5:1 ratio in this build.

Crane has a cam that uses easy ramps and will fall right into the static compression ratio range we will use in this motor. #10017 has an operating range of 1800-5400. Here's the 100172 kit which includes lifters. Always buy your lifters with the camshaft....that way you know they were produced by the camshaft grinder, not some fosdick Chinese outfit....
http://www.amazon.com/Crane-100172-E.../dp/B000CIRW8I...

...
RPM HP TQ
1500 122 426
2000 174 457
2500 217 457
3000 268 470
3500 315 475
4000 354 465
4500 380 441
5000 373 392
5500 326 311
There you have it boys and girls, a tire-shredding motor with a "flat-as-a-table" torque curve and a cam that will have a slightly rough idle so the OP can pose cool down at the Sonic Drive-In.

The OP should read this tutorial over as many times as it takes to make good sense of it and understand completely what it says......
http://www.crankshaftcoalition.com/w...ips_and_tricks

The parts list noted above is good as well, a lot of it is a "GM vs Ford" thing, as both make good products (just like Isky, Schneider, Comp, and Crane make some good cams).

What TechInspector said about chinese stuff is generally true. Not everything they make is junk, but I'd rather not risk it (plus, let's keep our American cars all American- and our fellow American citizens at work too).

I'm not sure where the dyno numbers came from, but note that if it's based off an actual build the numbers can vary (just like with production cars), piston rings, oil used, etc. Computer-dynos are usually accurate to + or - 10%, I think gross HP (no water pump or alternator, measured at the flywheel). Net flywheel HP I think you'd be safe to subtract 15 or 20 hp for the alternator, water pump, and power steering to get an estimated output.