Just spoke to the Eagle guys at the PRI. We tossed around a possible Cast Steel 3.75 stroke crank for SBO for under $400.00. Any interest? Posted this in another site and so far the response has been very good. I'll be taking this feedback back to the show this weekend.

Let me know what you think.

 

I'm in.

Gene

 

I support it 100% and appreciate the effort.

I probably will never buy one however.

Scat Chevy cranks are $150. There's just no way to compete with that.


GM made so many small block Oldsmobiles, that we won't run low on cores for another 20 years. And by that time we will all be dead.
See you all in 2012.

 

I figure I bought my last crank with the 425. But I do feel there are many who will purchase one of these cranks and I hope they do produce them!

 

I must be slow here, but I don't see the point. After buying this custom crank, plus custom pistons and possibly rods, even in a 403 block all you get is 446 cu in. Why not just use a 455 and put the extra money into go-fast parts? OK, I understand the more favorable bore/stroke relationship, but if you were really worried about that, use a forged 425 crank in that 455 block and still be close on the displacement.

 

Joe, there are some of us that just plain-*** don't want to use a 455. Oiling and such are not a problem with the SBs. The blocks are stronger, so less worries. I also don't want to use a 40 year old crankshaft.

 

While your DX-based motor is very impressive, why is the oiling on an SBO any different than on a BBO? Same galleries, same passage lengths - the only difference is the distance that the oil needs to travel through the longer pushrods. Now if you're talking about bearing speeds, you've already demonstrated how to fix that on the DX block. I'm also not sure why non-diesel/non-NASCAR SBO blocks are any stronger than BBO blocks.

 

I like the level of the discussion here, this is a intelligent discusson. and good arguments from both parts. I´m just participating as a reader but I am very interested about the issue. Are there any known dynotest of engines of this bore stroke combination?

 

So let's say you put this crank in a standard bore 350 with new pistons and rods. What would the new displacement be and what type of power improvements could be had?

 

Bored .060 over it would be a 399.
Standard bore would make it a 388

 

OK if you bore an early (mine was a 70) block .098 over (4.155) with a 3.750 stroke you come up with a 406. Mine was a 380 with a 3.50 stroke.

As far as SB vs BB the reciprocating weights of the SB are much more favorable and less stress on the crank/bottom end of the block. A rod to stroke ratio of 1.80 to 1 is supposed to be ideal. A SB is 1.77 to 1. I don't remember the BB's but the cylinder wall wear is very little. Yes the bearing speeds, both rods and mains are much better. I have never heard of a SB pumping the oil pan dry.

As far as the racing goes, I feel I have one of the strongest bottom ends out there. My first 380 in the gas block and would have lasted many years if I wouldn't have abused it so bad with only solid motor mounts.

Of course these are JMHO.

 

What would be needed in the way of pistons and rods? Would they need to be custom stuff? Or could one use something from a different application?

 

With all due respect, most people don't build 455's for HP, they build them for the low to midrange torque.
Take a 455 vs a 454 Chev, same cam, cr and everything. Put the best available heads on it for the package and I bet the Chev will out hp the Olds buy a bunch. Then you can get into the longevity issue after that. BBO just take more $$$ to make live and perform.

I guess I'm having a problem here as well. I don't get why the Olds community wouldn't welcome a SB stroker kit with a decent crank, good I-beam rods (Chev 6.00 SB rods) and Hypereutectic pistons (Chev 400 SB 5.7 rod comp distance) for possibly under $1000.00. I don't get it. Put the extra money into making what heads are available to actually be able to make some hp. Isn't it time we all quit having to pay so much more for what the Chevy, Ford, and Mopar guys already have? I certainly think so.

I spent 45 minutes or so with Joe Mondello at the PRI. He was all for it as well as telling me what's wrong with the Edelbrock heads. He said his piece on HP TV was true. After doing all that work to the heads and having a decent size cam in it it still only made 450hp. That same combo in a BBC even with oval port heads would've made another 50hp, easy. I know, I've done it. He agreed.

Let's take what someone may be willing to give us and quit the bitchin!

 

I'm not complaining, just asking the question. This is supposed to be a cast crank, not forged. I have to wonder if that price is a US-cast crank or is it Chinesium? An extra 0.4" of stroke will require custom pistons with custom compression height. I'm guessing that your $1000 estimate is off by at least a factor of 2.

Frankly, I would rather see someone cast a set of Olds heads based on the LSx family ports and chamber design. These heads are why the LS motors make such insane HP numbers so easily.

I'm also still at a loss to understand why, if an SBO won't suck the pan dry, how is a BBO with the same pan and same oil pan any different - other than the fact that the oil to the rockers has to travel an extra inch to get back to the pan.

 

Where do you guys get this CUSTOM rod and piston bullshit?

Do the math - a SBO averages about 9.325 deck height, 3.75 stroke divided by 2 is 1.875. That plus a VERY available 6.00 SBC rod and a VERY available 400 SBC (5.7 Rod) piston (1.425 comp distance) equals 9.300. Deck it to that if you want and you're home free. Good rods are $250.00 all day and a good hypereutectic piston is $300.00 a set. Just go to any of a hundred websites, you'll find em all day long. Don't make it more difficult than it needs to be!

And by the way its .365 not .400. Step out of the f...... box every once in a while O.K.!

 

Thanks Mark.

 

Thanks for that.

Reasonable, intelligent people ought to be able to discuss differing opinions without resorting to four letter words (or seven letters in this case). Your selection of existing Chevy components that work in this application is great and obviously cost effective. My opinion, based on exactly zero experience with a combo like this, is that for all the mixing and matching of custom cast crank, cast pistons, etc, is that the resulting 401 motor won't make any more power than a 403 built to the same level and using comparable parts. I hope someone can prove me wrong.

Ultimately both motors are limited by the heads, and even the best available aftermarket Olds heads are limited by the basic architecture of the Olds engine. Batten had a good start with heads that were not constrained to fit the existing Olds intake and exhaust interfaces, but port and chamber technology has come a looooong way in 30 years. Witness the new SBC heads featured in this month's Hot Rod that incorporate features from the LS heads.

I'll be the first to admit it when I'm full of manure. As I've noted already, I have no firsthand experience building a motor like this. In this case I'm just asking questions.

 

If the port design in the heads are the limiting factor for olds engines just take them out of the equation and force the air through them.

Just get the strongest stuff already avail for olds. Clean up the heads, valves and bottom end slightly and BOOST the bitch.

 

Joe, just think of weights. Less weight in the rotating assembly means more HP, faster revving, and less stress on the crank and block. Most Chevy aftermarket parts are lighter than Olds parts. There is quite a difference in piston pins alone (.980 to .927).

 

I understand that, but the longer stroke increases the acceleration and deceleration loads at the ends of the stroke. This increases loads on the crank and block, but I'm too lazy to do the math to figure out which is worse.

Structurally, a smaller diameter piston pin must have a thicker wall to have the same strength and stiffness as a larger diameter one. As a rule of thumb in the structural engineering world, if stiffness is the design driver, larger diameter is more weight efficient. If strength is the driver it's cross section area and diameter is irrelevant to weight since the required cross section area of the material is fixed. Others have adapted Type C rods to a standard stroke crank, of course.

I would also assume that if quick revving, high-RPM drag strip use were the intention, one would not want a cast crank and cast pistons anyway.

 

Wow, interesting read and way over my head but for a while I thought I was at ROP.

 

......

 

This is the same thing that always happens when talk of a new product comes up. Everybody wants something different. Racers want high quality race parts, street guys want affordable bolt in parts. The economics is simply that there are not enough of us to justify tooling up for the small market demand. Why hasn't somebody marketed an 8.5 to 1 355 that is computer friendly to replace the gazillion G-bodies with 307s? And even full sized vehicles where the extra power would be nice, like a wagon that tows? If there was a market, there would be a supply, economics 101

The point that Joe and others make is valid. 350 and 403 cores are plentiful and for most guys are adequate for their needs. Do a basic rebuild and spend $1000 or so on the heads and for $4000 you have an easy 400 HP engine that is dead reliable. I am not a huge 403 fan, but IMO it is not thew windowed webs but the flimsy cylinders combined with the huge bore that makes honing and ring seal an issue. But that is just my personal opinion.

I think a big inch SBO would be great, and with the early 350 heads would make a fun, responsive street engine. Would they sell? I have no idea, but you would think so, especially as a kit priced around a grand.

 

Yeah - I want big block parts.

Seriously, I've never built an SBO, only BBOs. Consider me the little kid who's always asking "why?" It just seems to my limited view that a 10/10ths race motor will want a forged crank anyway, and the use of lightweight Chevy parts in Olds motors has been done before. I'm not the target demographic for this crank anyway, so feel free to ignore me. I'm just curious.

 

My post wasn't to be a nasty or bad comment in any way. Just that this kind of in-depth engine discussion usually shows up on ROP instead of here.

captjim, I think you have a good point. Economics prevent us Oldsmobile freaks from enjoying the kind of availability of good stuff at reasonable prices that the Chevy and Ford guys get.

 

To quote the venerable phrase "There is no substitute for cubic inches" most will agree that bang-for-the-buck the 455 is a better option, at least in a street car. At higher HP levels, IMO the small blocks have proven more reliable over time. But, there is a place for small block drivers. Easy swap for 307s, get close to 20 mpg, no overheating or hot starting issues, and still run mid 13s with a 3.73/OD combo. And most will agree that for a nitrous or forced induction application, the SBO is better. I sprayed my cast pistonned 355 with a 3.42 gear and ran 12.7s while never seeing 5,000 rpm (shifted at 4800). The engine still runs great, though I would certainly recommend using forged pistons for n2o.

 

OK, but based on what? If improved reliability is the result of the 3.385 stroke, then a stroker crank just makes it more like a BBO, right? If reliability is bearing speed, others have turned journals and fabricated bearing spacers. If reliability is the result of starting with a DX block, well, that's a different thread.

Admirable, but I would argue that a properly installed BBO will do the same (well, the 20 MPG will suffer due to the increased pressure from the right foot).

My personal experience is a 462 with forged pistons built from a PAW "white box" kit that I sprayed with a carb plate system and went 11.9s with 3.42s (and tires that were way too tall) in a fairly heavy 71 Cutlass. Totally stock small valve heads. Car ran great until it went away in the first divorce.

 

I think that the number of failed 455s vs 350s speaks for itself.

I think you discount the fuel economy issue. No way you are getting close to the mileage in a 455 that you will a 350, IMO. And though not difficult, it is not a drop in swap as the 355 would be. And, there are waaaaaay more 350/403 cores available.

BTW, does anyone know how the 4.50" BBO cranks are selling? Just curious.

 

I don't have any data, so I'll go with yours. Two points, however.

First, does this data account for the size of the initial populations? In other words, if there were more 455s built for racing, one would expect more to be broken, even if the failure rates were the same. That's why the IIHS quotes total annual deaths on the highway whereas the DOT quotes fatality rate per million miles driven.

Second, if the failure of BBOs is due to the long stroke and heavy pistons, doesn't increasing the bore and stroke of an SBO start to cause the same problems? As an example, it would be interesting to compare the loads in the reciprocating parts between the stroker SBO we've been talking about here and, say, a 425 BBO - or better yet, a short stroke 400.

 

We have slid off topic, maybe time for a new thread. But, to the OP, this is what I stated and stand by it,

"To quote the venerable phrase "There is no substitute for cubic inches" most will agree that bang-for-the-buck the 455 is a better option, at least in a street car. At higher HP levels, IMO the small blocks have proven more reliable over time. But, there is a place for small block drivers."

This proposed crank seems like a good deal for a modest pump gas street/strip or hot rod engine.

 

Good feedback. Joe, sorry for the expletives but sometimes I get frustrated. I expect and welcome the questions, however sometimes its good to do your homework first so we can move things along. Not blaming you but I've had to restate the same info more than once.

As far as bearing speed goes, a non issue. The rods will be SBC size and the mains stock Olds size. You will obviously have greater piston speeds with the longer stroke but durability should be increased by better lighter parts. Again should be a non issue. The Chevy parts that most would be using are already proven in this environment.

Jim you're right as always. I see you understand the economic picture especially in todays economy. I just wish others saw the same.

 

I have raced BBs. One year a 468.......8.5 to 1 with nothing special. The other BB was a 496 that we tested converters and rear gears for a friend. Both scared the hell out of me with low oil pressure. Oh and no Giggle Gas for me. I want to do my ETs NA.

If this crank would have been available at the time we started my current motor, I would have went for less HP and went with a 406-407 cube motor. Saved on the pocket book and still been durable with Chevy style rods and pistons.

 

Right as always??? Where is my buddy Norm when I need him??
Seriously, though, the last time I ran brackets there were 4 lanes of cars and I stopped counting at 50 per lane. Over 200 cars, and that just in "Sportsman" Mine was the only Olds powered car. Several Oldsmobiles, but the others were sbc powered. Funny video here, even the track announcer was surprised! (the guy went red and I was dialed in so I took it easy)
http://video.google.com/videoplay?do...1264829763544#
So what truly is there as far as a markert for Olds powered cars is concerned? Compare that to even the Buford and Poncho guys and we lad far behind.

 

I can't argue with your first-hand experience, but you and I both know that the galleries and internal oil passages are identical on the BBO and SBO. The only differences are the different bearing diameters and the extra inch or so for the oil to get to the heads and back. Oh, and as discussed in another thread on this site, the BBO has extra oil drainback paths in the valley. I'm just struggling to understand why a BBO and an SBO with the same oil pan, same pump, same bearing clearances, same oil weight, etc, would have different oil pressure at the same RPM.

 

I am no engineer by any means. I do plan on asking a friend who dynos and sets up oil pumps if there is a differance right off the bat. I do know for a fact he asks what the application is. Clearances are also a major factor. I would assume the larger mains and rods make alot of difference. Larger obstructions means either lose pressure to get thru or increase pressure from the supply. This of course is just my opinion.

 

OK guys, if you don't mind humoring a novice I'd like to back up and summarize the proposed benefits and ask a few dumb questions.

Extra stroke - I get that. More cubes and more torque. So at +.030 what displacement does that result in for a 350 and 403?

Uses Chebby rods/pistons - cheaper and more options out there, lighter parts available. What about the issue of valve reliefs? Is there anything to that? Why not flat tops? Are there no dished pistons for Cheb applications?

If the crank is "cast steel" as opposed to nodular iron, is it any stronger than an OE crank? It isn't clear to me whether this is just marketing spin or an actual improvement over OE. Any potential for higher RPMs? Is there really any advantage to stronger rods and pistons if the crank isn't forged?

I guess what I'm trying to understand is how much bang you get for your buck by going this route vs. using a stock or modified OE crank. Seems like there is some potential here. I mean, think about why guys spend on aftermarket carbs, manifolds and headers and I'm thinking gain less HP per dollar than you would get out of this.

Then there's the question of why not just go for a big block. I can see where G-body and 403 T/A guys might not want to hassle with fitting a BBO.

 

I'll answer your last question first. First of all not everyone wants to make that switch as big blocks sometimes need more work to stay dependable (i.e. Girdles etc.)

An aftermarket cast crank may not be stronger than a nodular but you can't get a nodular in 3.75 stroke, not even by going to a Honda size rod journal. Moot point.

There are dished pistons, flat top pistons, and dome pistons available for Chevy. Just look at any catalog. I think they even sell them at 7-11!!

Valve refliefs won't be an issue unless you're going fairly large on the cam. They can almost always be remachined.

Cubic inches would go from about 393 to 450+.

Just an FYI for everyone. I spoke to another crank company yesterday. There is interest there too. I'll keep you posted.

 

very interesting thread.

 

Talked with Milan this morning and he told me he automaticly adds more shim to a BB pump over a SB. The reason is what I gave.

 

OK, but that still doesn't answer what's different and why there should be an oil pressure difference. The only physical difference is the larger bearing diameters. Now, that COULD be a significant difference, since at the same bearing clearance the larger circumference of the bearing provides additional oil "leakage" area and thus might be the cause of the lower oil pressure if everything else is the same. Cutting down bearing journal sizes would solve this problem, of course.