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Engine Design Options...Two ways to build a 509?...aw heck, lets make it a 632BBC !!!

Greg72

Greg72

@MIGHTASWELLK5
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A "typical" 509 is built with a 4.500" bore and a 4.000" stroke crank.

I've been considering doing a 509 build using a 4.500" crank instead and a smaller bore size (4.240")... 508.3 cubes.



A couple of reasons:

I am seriously contemplating the use of an aluminum BBC block (Bill Mitchell Merlin-X) which supports a maximum crank size of 4.500"... if I simply go to the max on the bore size (4.600") it will end up at just under 600 cubes. This may be a case of "simply too much" engine, even for a heavy K5.

My thought was to use the 4.500" crank (and only have to buy an expensive crank once!) and use the "factory bore" of 4.240" to build up a much smaller 509-inch motor. I could run it in that configuration for a while and if I didn't scare the bejeezus out of myself, I'd always have the option of boring the block for more cubes.....but re-using the rods and crank to build a 600-inch monster.



The main question is really what the effect would be of building a 509 with this "oddball" configuration (small bore, large stroke)?? My suspicion is that the torque curve would move substantially lower in the RPM range (more torque sooner) which would be a welcome thing. I'd love a big FLAT torque curve that reached it's peak VERY early and would stay flat all the way out to something like 5000RPM (or more).

Has anyone run a DesktopDyno on confgurations with exaggerated stroke lengths? Dyno charts? Real World experiences??


Right now, this is still in the early planning stages....but Bill Mitchells shop is only about 5 hours away, so the temptation to have him build me something and watch it run on his dyno is very tempting!! :saweet:
 
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I just got to say with an engine that size and quality compononts your torque curve will look like ummm Kansas or more like the middle section of this country, I think it is a moot point but I would go with the smaller bore too because if you have any problems in that area you can clean up the bore with a larger one
 
1 issue you may want to look into is side loading of the cylinder walls.(piston skirt wear) i would think the smaller bore would tend to make those problems worse! :dunno:
 
hot rod magazine did a test on a short versus long stroke test a few months back. they used roughly the same displacement, with the same intake heads and cam. they found virtutually no difference in hp vs. torque. wish i had the issue here so i could give exacts, but is in the june 2005 issue.

*edit*
and they found that the rod ratio isn't as important as we were led to believe in the past. say that on a normal 350 a 6" rod may only increase by 3hp at high rpm.

ryan
 
blazinzuk said:
I just got to say with an engine that size and quality compononts your torque curve will look like ummm Kansas or more like the middle section of this country, I think it is a moot point but I would go with the smaller bore too because if you have any problems in that area you can clean up the bore with a larger one
Click to expand...

You are right. In fact the mininum bore to maximum bore for this block is quite substantial:

Min = 4.240"
Max = 4.600"
Difference = .360"
Number of .030" Overbores available = 12!!

That's a lot of rebuilds, assuming I don't do something catastrophic like window the block somehow along the way...... :D
 
Greg72 said:
That's a lot of rebuilds, assuming I don't do something catastrophic like window the block somehow along the way...... :D
Click to expand...
Ah, but you forgot the most awsome thing about using aluminum. It can be welded/filled and remachined. :cool1: I've seen aluminum heads that came from racing engines that dropped a valve and then valve parts got pushed through the head. A little TIG welding and some machine work had them looking like new again. :D
 
Personally I'd go with a larger bore like 4.5" An engine this size will need to breath and the larger cylinders will unshroud the valves. Even if you were to "only" use a 4.25" stroke it will still make more torque than you can use.
 
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Hi Greg, my 504 is 4.310 (.030 on a stock 4 bolt iron block (boo hoo, no alum block for me)) with a 4.375 crank and it works really nice. It's not a high RPM motor, with that displacement the edelbrock big ovals should run out of breath and the cam redlines at 6K (usable to 6K, float at 6500).
Dyno number guess by myself and Zack at 505 performance was about 575-600 for HP and probably 600 plus a little on torque. Assuming perfect air and tuning and all that nonsense that never happens.

The only reason to limit the stroke is mechanical stuff like clearance on the block or to limit your max piston speed and you're probably not going to run into piston speed issues with the rpm's you're looking to run, even with the 4.5" stroke.

Personally, I'd build it the way you want it to stay since changing motors around isn't cheap or easy. So I'd bore it pretty big to begin with. You're also going to have head choice issues that depend on displacement along with the rest of the motor since there's a big difference between 500 and 600 cubes.

Keep in mind, with my motor (similar to your smaller displacement numbers but way smaller than your available options) I have the torque to do anything I want offroad and it drives really nice in overdrive with the 5.13's and 42's on the road. I don't want to say any more than what I have is ridiculous because I wouldn't mind having to make the decisions you're working on but you're going to have plenty no matter what you do within the range of displacements you're dealing with.
 
I'd say the 4.000" stroke would be more for a race motor.. like my 469 that winds to 7K..
4.25" would be for a 496 stroker, and 4.5" is even more stroke, so i would think 5500rpms would be pushing it!

You might want to look into a 427 tall deck block (10.2 deck height) instead of a high dollar aluminum block to get the same deck height.. sure its not cool and lightweight, but its a hell of a lot cheaper. I have a 4 bolt main 427TD in my garage i got for under $100.
punch it .100 over and 4.5 stroke crank will yeild 535 cubes. .120 over (max) will be a 540. I believe you can even get an expensive 4.625 stroker crank with clearancing the block and it would be a 572 or possibly just a hair over 600 cubes..
Someday i plan to build it up when i have enough money.. Have close to a 600 cubic inch motor that i'll call a 396. :haha: And just by looking at it you'd see a factory block. :wink1:
 
I would suggest that you watch what happens with the upcoming engine masters challenge. Many builders are going the small bore longer stroke route. I personally like the longer stoke route for a trail rig because it does most its running below 4000rpm.
George
The challenge is set to happen in mid october at world products in long island n.y. The engine size this year is 509 cubic inches.........
 
only wish i had that kinda money to build just an engine ;) :waytogo: ill end up waking up my 454 with port job and large valves and headers large exhaust and a cam lol
 
I would think your cam spec's would change if you were to re-do your motor and gain a hundred , or so , cubes. I realize that you are making power in a specific RPM range but to make use of those extra inches I would plan on using a 4.5+ bore to start with and make use of head work and cam spec choices accordingly.
I think it is great that you are going with such "top shelf" parts and using them where they can make a difference!
Good luck and please keep us posted on what you decide to do .
Tom
 
DAGNABIT! just about the time i get over finding the info on the CanAm 509, yall bring it up again, and make the tourque fairys swim around in my head. anyway heres my advice. your useing top notch parts and a reputable engine builder. build it the way you want it and dont go out the first day and TRY to break it :haha: if you build it with reliability in mind you shouldnt need to rebuild it later. the whole point of huge displacement is the higher numbers it can produce reliabley. sure you CAN build a 800hp small block but everyone knows its not going to last as long as a 400 hp small block. you build a HUGE block engine ans high power numbers are going to naturaly follow. maybe im wrong but it makes sence in my head that you should be able to build a 500-600hp 509 thats relaiable.

balzer
 
Losing interest in Aluminum Blocks....but gaining interest in BIGGER Cubes!

I've had a few phone conversations recently with both the Shafiroff and Bill Mitchell shops, to discuss my idea.

The first thing I've learned, is that the upcharge for using an aluminum block is NOT merely the difference in price between the iron and aluminum blocks as shown in the catalog (~$2500 vs. ~$3500 or roughly an extra $1000). It is in fact more like $3000 to $3500 MORE than the iron block!!:mad: Beyond that, the weight savings in "real life" is not 130 Lbs...it's more like 75 Lbs. Suddenly the cost/lb of weight savings is a LOT less sexy than previously thought.

Additionally, the aluminum Merlin block doesn't support the larger stroke and bore of it's iron counterpart. Some of the very expensive Donovan blocks would work, but at an even more stratospheric cost...The whole situation is starting to feel like a lose-lose-lose proposition.



So my new approach is to get back to a more convetional iron block / aluminum head BIG bore, BIG stroke motor.

There was in interesting article in ChevyHighPerformance recently about a GM572 crate motor that they bought and modified with a dual-plane intake and a more mild "bottom-end" cam. The torque gains at the bottom end were impressive! Something like 600 lb/ft @ 2000RPM, which would be great for a heavy truck. They lost about 100HP, but got a more driveable, and streetable motor.

My latest thought is to do a similar exercise with a longer stroke (4.75") and a decent size bore (4.50" = 604ci) or (4.60" = 632ci)....but instead of using the typical single plane high-rise intakes and hot cams that are normally used in the "crate versions".... take a loss on the HP, but bring up the bottom end TQ with the dual-plane intake and milder rollercam.

Anyone feel like running a simulation on DeskTop Dyno to see if there's a way to get something like 700 Lb/Ft at low rpms? (like 1500 or 2000?). I'm thinking with driveline losses of 30% (probably conservative) even an impressive number like 700 ends up being more like 500 by the time it actually gets out to the wheels..... :thinking:
 
One thing to keep in mind is that even with a bit of a "mid range" motor that big, you'll still have gobs of low end torque and for offroad use, you have to have some low gears anyway so you may be able to build more for the middle and not lose anything.
My cam is a crane "powermax" roller, 226/234 @.050, good to 6K and it has a heck of a jump just off idle and the idle is nice. The rest is edelbrock big oval heads with their multiport. comp is about 9.5 to one, maybe a touch more. Hopefully this is a good reference point for you. Come out to BB05, I'll take you for a ride!

Being where you are it's hard to not talk to the shop you're dealing with, if you were closer to here I'd say you should talk to 505 Performance in Farmington, Zack is really into big blocks.
 
Hey Stephen,

One of the things I liked about that CHP article on the 572 was that they said when they were done with the manifold/cam swap, the engine had something like 19" of vacuum at idle!!! My guess is that the engine idled "normally" and didn't sound like a top-fueler hunting all over the place. You could still even use a standard brake booster setup with that kind of vaccuum.

The other thing on my mind is that on the trail, it would be nice if the engine didn't make a racket at low RPMs....it would be nice to hear a spotter talking, or just to be able to loaf over obstacles at a low idle without going deaf from a lumpy, aggressive-sounding cam..... of course if I wanted to romp it in some sand, I wouldn't mind if it sounded nice and raunchy!!! :saweet:

No BB'05 for me, though I appreciate you offering me a seat. (just flew out for the Hollister event last month). I'll will be trailering out for the '06 event, but it's doubtful (OK, impossible!) that the '69K5 will be ready by then.
 
Greg72 said:
Anyone feel like running a simulation on DeskTop Dyno to see if there's a way to get something like 700 Lb/Ft at low rpms? (like 1500 or 2000?). I'm thinking with driveline losses of 30% (probably conservative) even an impressive number like 700 ends up being more like 500 by the time it actually gets out to the wheels..... :thinking:
Click to expand...



Scotty??? You out there....? I figured I would have heard you 'weigh in' on this thread by now!!!! :D

C'mon dude:

AFR 315 Heads
Roller Cam
Blah, blah, blah...

Run a few numbers or send me a "loaner" CD! :D
 
My opinion is that you are onto some good sound thinking with the mild big inch motor logic. A local Pro-Stock racer built a nice oval port ( stock GM 781 castings with larger valves ) 572" ( 4.5" x 4.5" ) for his pull truck and it made all the other "tweaked" gas burner pull trucks feel weak ( this was in the early ninety's and before the diesels in 1-Ton trucks made incredible power out of the box).
I would think that your head choice and a 4-3/4" stroke would have all sorts of bottom end grunt even if your cam selection is at , or above, 240/250* at .050 . Remember when you are talking to the pro engine builders that they are not normally dealing with a customer that wants power in your RPM range with such a large motor. Keep reminding them that you are not after peak power at a narrow power band when parts are being discussed .
What rod length will you be going with if you decide on a 632" ? Just wondering if you will put the pin lower in the piston and use a shorter rod since this application won't see the loads impossed by an all out race engine.
Once again , I think it is GREAT to see someone make use of cubic inches and use them for what they do best in our sport !
Tom
 
I just did a DD calculation, and while I now know that DD is a ****ty program, and not to be trusted, this is just a estimation. Apparently, with a 631 cube motor (502 block bored to 4.600 and stroked to 4.75), WP Jenkins Merlin Aluminum Heads with 2.50" intake and 2.00" exhaust valves, 9.0:1 compression, Large Tube headers with open exhaust, 1100CFM Demon Carb, Dual Plane-High torque intake manifold, and an 11-230-3 cam, you should be puting out around 800ft/lbs at 2000rpm (more at 600rpm, likely closer to 900ft/lbs at idle) and 430hp at 3500 rpm. Not a bad idea... but again, DD has never been accurate, so I wouldn't put much faith in it.
 
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