Elliott
Isn't the steeper rod angle part of what helps the 401 build torque faster per comparable level of build then other small blocks? Obviously there is a point of diminishioning return. I ran a lot of comparisons trying to figure out why the Caddy 500 is such a relative dog and I think it's much more then just the heads, I think it boils down to rod angle, possibly lighter crankshaft counter weights and stroke? What I mean (and this is a dis on big blocks :wink: ) if you took a bone stock 401 and simply added 99cubic inches to it and nothing else, compared actual net hp and torque the AMC would walk away hands down.
I know, I know, I should run my motor instead of my mouth... so I'll keep this short until I have the income to put my plans to work. I've never put even 100,000 miles on any vehicle or engine I've ever owned so if I get that out of a 500CI AMC whether I build it or use an ICH block I'm sure I'll get my moneys worth of smiles out of it.
For the moment I have to focus on getting my shop built, but I enjoy reading about your build and look forward to the dyno results... gotta feeling you will be quite pleased. :mrgreen:
Now as far as proportional gains, if you took a GM 400 and threw a hundred cubes at it you'd still have a POS. For what you get in a big block 500 it's really comparably pathetic if you look at net hp and were to use the same compression ratios as the 401. For the extra 99 cubes in the caddy, the BEST net hp rating with higher compression pistons only made 120ft/lbs torque over the 8.3:1 mildly cammed Jeep 401. If you could throw another 100 cubes at the Caddy I don't think the block could take it (it darn sure won't rev to 7,500) and you sure wouldn't get the proportional increase in torque that you can obtain from a 401. Running pump gas I just don't think you can double a Caddy's torque by adding 100 cubes, or any other big block for that matter. Sure you can ultimately build more power in a big block, but not so sweetly as the AMC. Does make me kind of wonder what you might end up with if you threw 100 cubes and the ICH Bracket Master 500 though! (Although I don't think you could.)
so much for short...
Block hardness? There must be enough of a difference if the AMC crowd will race with 7-800hp on two bolt mains. Doubt there are any 4bolt main big block lovers out there running hp like that who would take two bolts out of each main cap and have the same confidence in their block. Program has 4 bolt mains for the 401, Miloden used to.... but does anyone need them... or even buy them? Maybe you would want them for 1000hp, but would a GM 4bolt small block even handle that much HP?
AMC, as a small block... just flat rules :t:
jeepsr4ever
here is a little to add to the fire
Edelbrock insider told me this.
They have on a Dyno a 480hp 401 here are the specs
401 stock bore stock crank stock pistons
Edelbrock heads, EFI, (special NEW camshaft) headers.
:!:
I magine with a bump in stroke and compression
Oh and as far as rod throw and angle are considered, you guys are close to understanding the mystery of why AMC V8's (of larger displacement) are power mongers :idea: devils in the details men :wink:
J20
I have tremendous respect for those Edelbrock engineers. I'll go a little further out on my stressed and already cracking limb and surmise the Edlebrock engineers have concluded the optimal stroke for the AMC V-8 is somewhat less than 4 inches (3.9ish) and with max bore (.060) will finish at about 440 cubic inches. (What if connecting rods with offset rod journals where used like those in some of the bigger inline engines?expensive!). I'll further surmise Edelbrock has already done the dyno on the 440 cubic inch option with a 250 to 260 (I may be a tad, 5-10, low on cam spec) duration roller cam, 10:1 compression ratio, Edelbrock Pro Flo EFI, Edelbrock Performer RPM heads and got 600 - 650 hp at about 6500 rpm. How close am I?
J20
I'm not sure where the extra (I’) and others came from. I do know my previous message took forever to post.
jeepsr4ever
:-|
J20
Okay, here is the MATH. The following tables contain theoretical calculations for rod angle, compression height, compression ratios, piston dish depth/volume and a compression height minus a ring pack thickness of .4375 minus ¬? of a .927 (.4645) pin diameter. These numbers are approximations as I do not have exact piston manufacture's dish rim thickness or ring pack dimensions (I approximated it at .4375 and .25 inches). I also did not include any room for bearing clearance or head gasket thickness because there is a lot of difference(.003 - .006 and .025 - .060). Again this is simply a guide. You will note the negative values for the dimension between piston pin and bottom of ring pack as stroke goes over 4 inches in the 9.3:1 compression ratio case and over 4.135 in the 13:1 compression ratio case. What that means is there is no more metal, you hit the wall! Look closely at the 3.92 inch stroke, 9.3:1 compression ratio utilizing a 6.125 inch rod with a 18.66 degree rod angle - there is .004 material above the piston pin. That is why I consider the 3.92 inch stroke the maximum for the 401 at a street level compression ratio keeping the oil ring out of the piston pin. I chose the 3.82 with a 6 inch rod and 18.66 degree rod angle with a compression height sufficient enough to leave some metal above the piston pin. Again these numbers are simply a theoretical guide. Your exact build will vary up to maybe .100.
stroke.....stroke/2.......Rod........Rod Angle....Comp.....Cylinder..Final
...............................Length........................Height....Volume...Volume
3.68...........1.85..........5.85.........18.33........1.52.........51.593.......412.74
3.82...........1.91..........6.00..........18.56........1.30.........53.556.......428.45
3.92...........1.96..........6.00..........19.06........1.25.........54.958.......439.66
3.92...........1.96..........6.125........18.66........1.12.........54.958.......439.66
4.00...........2.00..........6.125........19.05........1.08.........56.079.......448.63
4.00...........2.00..........6.135........19.02........1.07.........56.079.......448.63
4.135.........2.0675......6.25..........19.31........0.89.........57.972.......463.78
4.135.........2.0675......6.35..........19.00.......0.79.........57.972.......463.78
4.25...........2.125........6.35..........19.55........0.73.........59.584.......476.67
4.35...........2.175........6.535........19.44........0.50.........60.986.......487.89
Stroke....Piston Dish...Apprx.......Piston........Comp Height
..............at 9.3:1.......Dish..........Dish.........- Ring Pack
..............Cubic In......Depth........Cubic CC..- Dish Depth
................................................................- 1/2 Pin Dia
3.68........2.009..........0.184.........32.92........0.433
3.82........2.220..........0.204.........36.37........0.193
3.92........2.370..........0.218.........38.84........0.129
3.92........2.370..........0.218.........38.84........0.004
4.00........2.491..........0.229.........40.82.......-0.047
4.00........2.491..........0.229.........40.82.......-0.057
4.135......2.695..........0.247.........44.16........-0.258
4.135......2.695..........0.247.........44.16........-0.358
4.25........2.868..........0.263.........47.00........-0.431
4.35........3.019..........0.277.........49.47........-0.680
Stroke......Piston........Apprx........Piston.......Comp Heigth
................Dish at......Dish..........Dish..........- Ring Pack
................13:1..........Depth.......Cubic CC...- Dish Depth
................Cubic In.....................................- 1/2 Pin Dia
3.68..........1.44..........0.132........23.547.......0.511
3.82..........1.59..........0.146........26.021.......0.277
3.92..........1.70..........0.156........27.789.......0.217
3.92..........1.70..........0.156........27.789.......0.092
4.00..........1.78..........0.164........29.202.......0.044
4.00..........1.78..........0.164........29.202.......0.034
4.135........1.93..........0.177........31.588......-0.161
4.135........1.93..........0.177........31.588......-0.261
4.25..........2.05..........0.188........33.621......-0.330
4.35..........2.16..........0.198........35.388......-0.575
See the negative numbers? That means you can't do that. You can use a one ring ring pack but that is no good in a daily driver. Again this is a theoretical guide for an AMC block at .060 bore. This does not take into account the posibility of sleeving the block to a bigger (over 4.225) bore. If you increase the bore over 4.225 and keep the dish the same your compression will change. You'll have to recalculate to see if the compression goes up or down. Your actual results will vary some but not much. What say you?
J20
Bummer - the headers did not line up. Makes it hard to read but it is possible. Also, I don't know where the extra ’ stuff is coming from. Sorry.
J20
Custom hydraulic roller cam showed today in mail from Performance American Sytle. The specs are as follows: Crane Part No. 86HR00004
Grind Number HR-204/286-2-16. Lift Intake @ cam 286 @ valve .458. Lift exhaust @ cam 301 @ valve .482 both with 1.6 rockers. Intake opens at 17 deg BTDC and closes at 63 deg ABDC with advertised duration is 260. Exhaust valve opens at 74 deg BBDC and closes at 16 deg ATDC with advertised duration of 270. Spring requirements are dual at 120 lbs closed @ 1.875 and open at 296 lbs @ 1.1415. Part number on springs is 99893. Cam Timing @ .050 intake opens at 9 deg ATDC closes at 33 deg ABDC max lift at 111 deg ATDC, 204 duration. Exhaust opens at 48 deg BBDC closes at 14 deg BTCD max lift 121 deg BTDC with duration of 214 deg.
20 May 2005. The valve springs Crane said will work will not work. The problem is the installed height of 1 7/8 inches is not obtainable with stock length valves, retainers and keepers, only gives about 60lbs of closing force, installed height is .1 too short. So, now that the stock valve won't work, the new plan is to use a bigger intake and exhaust valve, .208 and .176. This should get even better as we can make the engine behave as if there where .5 inch lift instead of .458/.482. More to follow.
J20
That goofed up chart realy bothers me. How do you post an excel spread sheet? I added the dots, looks much better.
Mudrat
J20 wroteThat goofed up chart realy bothers me. How do you post an excel spread sheet?
You can't - I've tried all sorts of things. Its the text code the forum software uses. If you put in more than 1 or 2 spaces the software concatenates the string so it's only a single space.
The only way you could 'make it look (sorta) right' is to use a bunch of ...........
Sorry dude, wish we could, it would make life easier :roll:
Mudrat :oops:
Elliott
I don't know, I'm not much on the math... but by what I interpret from your table (correct me if I'm wrong, it wouldn't surprise me) it looks like ICH has accomplished what shouldn't work with their 500.
They are working with:
a deck height of 9.40"
6.200x2.100 rods
4.150 crank
.927” free floating pins
1.120" CH pistons x 4.374" @~13:1
figure to use a 0.048 compression gasket
I just figured that if they could stuff all that in 9.40" I could shorten the rods to 6", use a thicker gasket, drop the compression ratio and fit it in the 9.208" deck height... I could even run the pistons up into the heads if I keep the cam lift low enough and run steel H-beam rods to minimize flex. Heck, I think I could even play with the pin bushings to get it all in there.
Am I nuts? :wink:
I'm only shooting for ~10:1 compression with peak torque at 2,400rpm. I don't really care what happens to the torque or hp after that 'cause if my tires (40X17GroundHawgs) are broke loose at 2,400 and I'm pushing 650ft/lbs there is still plenty of umpf to keep the lugs blowing mud out to 6,500rpm. I should have about 550-600ft/lbs off idle and with a doubler and NP435 I can put that in slow mo at 128:1.
With a Ross stroker piston (ros Mopar 400 flattop#9949 1.120CH and 0.990" pin) and shooting for 12.5:1 compression with 0.003 Deck Clearance and 0.048 Compression Gasket in a 401 with late model 58cc heads and 4.150 crank:
Deck face height of 9.208 minus 0.003 desired deck clearance = 9.205 desired height
9.205 (minus) 1.120ch = 8.085 (X)
4.150 (divided by) 2 = 2.075 (Y)
8.085 (minus) 2.075 = 6.010” required rod length
This piston fits in a 9.980" block with 4.15" stroke and 6.768" rods, with 0.017" deck clearance, dome cc -4, ring grooves are 1/16, 1/16, 3/16.
If you subtract the .768 off the mopar rod to equal the 6" rods I'd use, subtract it from the 9.980 mopar deck height that leaves 9.212" which is only 0.012" greater then the AMC deck height... so I think there is room to work in there somewhere.... with a custom piston.
J20
Elliot;
The 9.4 inch deck height makes a very big difference, ICH gets 498.87 cubes but the numbers you quote are also .149 over my table values, 4.374 bore vs. a 4.225 bore giving them an extra 4.38875 inches per cylinder and they get an extra 3 cubes per piston with the additional .2 deck height - 7.38875 per cylinder for a grand total 59.11 additional cubes. The extra .2 inch of deck height on the block also brings the rod angle back to about 19 degrees. If you use a 9.4 deck height in my table you will run out of piston at a 4.135 inch stroke with a 9.3 to 1 compression ratio. Funny thing is 4.135 - 3.92 is .215. .215 is about the difference between 9.208 and 9.4. How about that :? The deck height on my 401 block is only 9.208 inches tall and that is what the table is built on. So bottom line is I still don't think you can get 500 cubes from a 9.208 inch block. I would hate to see you waste a lot of money on a project that will not work. Where did ICH get the 9.4 inch block?
J20
Lets look closer at the 4.150 stroke in a 9.208 deck height block with a six inch rod instead of a 4.135 inch stroke with a 6.25 or 6.35 inch rod. stroke divided by 2 is 4.150 divided 2 is 2.075. Take the 2.075 and add a 6 inch rod and we get 8.075. Now take 9.208 and subtrack 8.075 and we get 1.133 inches. We have 1.133 inches to play with. Now, if we keep the oil control ring out of the piston pin we also must subtract one half the piston pin diameter. If we use a .927 inch pin we must subtract half of .927 from the 1.133 inches we have left. So 1.133 minus .4635 leaves us with .6695. Lets examine what this .6695 has to do. This .6695 must contain the ring pack and the dish (there also has to be about .005 clearance between the pin and underside of ring pack material). If we use a standard 1/16, 1/16, 3/16 ring pack with 1/6 between each we get a ring pack of 7/16 or .4375. Subtract .4375 from .6695 and we have .232 in left over. A 10 to 1 compression ratio will mandate a dish of about .24, maybe a few thousandths less. You are definately on the edge for I think your top ring is into the dish edge material, not a good thing. Considering the bore you plan you may get by with less dish. If you did manage to keep the ring pack in the solid portion of what is left of the piston, you might make it with a six inch rod but your rod angle will be 2.075 divided by 6 is .34583. Inv sin of .34583 is 20.2324 degress. I consider a 20.2324 degree rod angle to be excessive and chose to use a 6.25 and 6.35 inch rod in my table, you may not. I would not run this combo in a daily driver. This build would be pure race and is out of bounds for me. I think we are seeing the reason the big block Ch*vy is offered with 10.2 inch vs. 9.8 inch deck height when using a stroke greater than 4.35 inches. The ch*vy engineers are not willing to accept a rod angle greater than 19 degrees.
J20
If I won the 401 currently up for raffle at only $8 per ticket (can you believe that?), I would stroke it to 3.92 with a 2.00 6.125 inch ch*vy rod and stick it in a Wagy. Actually, It sounds like a very sweet motor and needs no further help. It would power the wagy just fine as is.
J20
You have been listening to me spout off about excessive rod angle. Try this on, keep in mind I’m not an engineer but the numbers speak volumes. I let excel draw some pictures for me today, pictures are worth a thousand words. I built three data pages (finally a use for that trig class), one with the stock 3.68 stroke, one with a 3.82 inch stroke and one with a 4.15 inch stroke. I then graphed the results. There’s definitely a significant difference between the 3.68 curve and the 4.15 curve. As much as I'd like to post the data table to this page, they are rather large (182 lines per set). Instead I’ll post a few key values.
For the stoke 3.68 inch stroke, 5.85 inch rod
Crankshaft
Deg After TDC….Piston Travel…..Rod Angle
………….....…………in Inches…………………..
0………………………0……………........…0
10…………………...02795………….3.1309
20…………..…….…11097……….…6.1756
30……………….....24651………….9.0482
40…………………...43048…………11.6642
45…………………...53892…………12.8504
50…………………...65727…………13.9422
60…………………...92000…………15.8066
70…………………1.21068…………17.1912
80…………………1.52049…………18.0443
90…………………1.84000…………18.3324
You will notice in the first 45 degrees of crankshaft rotation after TDC the piston travels only .53892 inch or 14.64% of the total stroke. In the next 45 degrees after TDC (45 ‚Äì 90) the piston travels 1.30108 inch or 35.36% of stroke (for a total of 1.84 inch or 50% of stroke). If you plot the piston travel with respect to degrees of crankshaft rotation for the whole 180 degree power stroke you get a very nice ‚ÄúS‚Äù curve or ¬? of a bell curve. The points I provided in all three examples only plot to 90 degrees. The other 90 degrees is like a mirror image with point of inflection at 90 degrees (I think I said that right) The rod angle graph makes a nice parabola if you graph the whole 180 degree power stroke.
For the 3.82 inch stroke, 6 inch rod:
Crankshaft
Deg After TDC….Piston Travel…..Rod Angle
…………….....………in Inches…………………..
0………………………0……………......…0
10…………………...03509………….3.4823
20…………..…….…11519……….…6.2505
30……………….....25589………….9.1585
40…………………...44685…………11.8073
45…………………...55943…………13.0085
50…………………..68227………….14.1143
60…………………..95500………….16.0028
70…………………1.25674…………17.4057
80…………………1.57833…………18.2701
90…………………1.91000…………18.5622
You will notice in the first 45 degrees of crankshaft rotation after TDC the piston travels only .559 inch or 14.63% of the total stroke. In the next 45 degrees after TDC (45 ‚Äì 90) the piston travels 1.351 inch or 35.36% of stroke (for a total of 1.91 inch or 50% of stroke). Percentages are virtually identical to 3.68 example. Again, if you plot the piston travel with respect to degrees of crankshaft rotation you get a very nice ‚ÄúS‚Äù curve or ¬? of a bell curve. The rod angle graph makes a nice parabola with only slightly steeper sides than the 3.68 graph.
For the 4.150 inch stroke, 6 inch rod
Crankshaft
Deg After TDC….Piston Travel…..Rod Angle
………………......……in Inches…………………..
0……………………....…0……………........…0
10…………………...03152………….3.4429
20…………..…….…12514……….…6.7930
30………………......27800………….9.9574
40…………………...48546…………12.8440
45…………………...60775…………14.1547
50…………………...74121…………15.3624
60…………………1.03750………....17.4276
70…………………1.36531…………18.9642
80…………………1.71468…………19.9122
90…………………2.07500…………20.2327
You will notice in the first 45 degrees of crankshaft rotation after TDC the piston travels only .60775 inch or 14.64% of the total stroke. In the next 45 degrees after TDC (45 ‚Äì 90) the piston travels 1.46725 inch or 35.35% of stroke (for a total of 2.075 inch or 50% of stroke). Percentages are virtually identical to 3.68 and 3.82 example. Again, if you plot the piston travel with respect to degrees of crankshaft rotation you get a very nice ‚ÄúS‚Äù curve or ¬? of a bell curve. The rod angle graph makes a nice parabola with noticeably steeper sides than the 3.68 and 3.82 graph.
Lets look at the rod angle curves. The significant difference is in how steep (slope) the curves are. If we use the derivative (finally a use for the calc class) we get the slope of the curve. The steeper the slope the more inefficient the engine becomes because more and more of the downward force is directed away from the bore axis because of the increasing rod angle. Also note that the rod spends a great deal (from about 31 deg ATDC to about 149 deg ATDC in all three examples) of it‚Äôs power stroke at over ¬? of the maximum rod angle. This implies that for over ¬? of the power stroke energy is being absorbed by the block (all inclusive) in the form of side force (heat) instead of down force. The key is how much side force is too much. Lets pick the point, 31 degrees ATDC, where the rod angle first exceeds ¬? of it‚Äôs max value. Note that cos has a max value of 1 at 0 degrees and decreases to 0 at 90 degrees. Note also that our curve peaks at 90 where the slope would be 0. Derivative d(sin u)/dx = cos u, (I looked it up on Google) let u = 31 deg. Our curve formula is (¬? stroke * sin u)/rod length. The slope for the 3.68, 3.82 and 4.150 stroke curve at 31 degrees respectively is .2696, .2729 and .2964. Now we need an automotive engineer to step in and say if the mains, rod journals, piston pin and cylinders can withstand that amount of deflection indicated by the graphs and calculated slope. For a long life, daily driven vehicle (I say again, for a long life, daily driven vehicle) I say yes for the 3.82 using 6 inch connecting rod but I say no for the 4.150 with a 6 inch connecting rod. Use a longer rod, say 6.125 or 6.135, I‚Äôd say yes, but a longer rod will not fit with a 9.208 inch deck height, standard ring pack and 10 to 1 compression ratio. Need I say yes for the 3.68 example? Someone might want to do the force vector analysis next, might yield interesting results. Does Fuzz401 have any insight regarding design history of the AMC 401?
Elliott
Regarding your ICH question, they cast the 500ci blocks from the design Herman Lewis put together.
Regarding rod angle, remember that ICH is running only ~0.55* less on a high rpm motor built for 600+ftlbs. What I don't know is that the ICH motor may actually have a significant amount of chatter at lower rpms that smooths out after 3,500 or more rpms, which would be above my peak of 2,400. From what I understand the 360 and 401 at ~18.30* made enough noise that the pistons on the low compression motors were offset .0625 inch toward the major thrust side. (out of curiosity how much would this effect the rod angle?) Why this wasn't done on the higher compression motors I don't know. Possibly the higher compression pistons had just enough more height to compensate for the side load and reduce vibration?
I realize that I am pushing the envelope to the extreme, but this isn't for a daily driver. The level of functionality is something I'm not sure could be computed based on formulas (although I will say the desktop dynos are very impressive) given that everything would fit inside the 9.208" block. There are probably more variables in the actual design and use of specific parts to be computed then formulas could completely diagnosis. Maybe I'm wrong about this because I don't know enough about using formulas to figure the specific dynamics, but computing the actual effects of rod angle in the 9.208 block would be effected by everything right down to atmospheric conditions, specific fuel grade and possibly valve timing... not to mention the specific weight of each component, specific rpm and the viscosity of the oil used.
Thanks for making sense of some of the math for me, I'm not too shabby in physics, but that's about the end of it for my mind. :mrgreen:
J20
Elliott is right. The mathematics only go so far, in that the formulas estimate the boundaries and make the builder aware of just how far they can go and the associated pitfalls of being on the edge. From there the builder must take into account every known variable and decide how far to push. My build is intended to maintain as close to stock geometry as possible while gaining a few (at least a 100+ across the entire rpm range) ft lbs of torque. Elliott is pushing the envelope and his build, if he can keep it together, will definately establish a new level of AMC performance. I hope it works.
J20
:? Update update update :?
Turning some wrenches. The Wiseco pistons on the Manley steel H-Beam rods with the 3.82 inch off-center ground crank and the Crane hydraulic roller cam work perfectly. Clearances between rod and block, piston skirt and crank, cam and rods all exceed .060 by a considerable margin. The pistons could have been .015 taller, need to shave about that much off the top of the block. Ordered from Bulltear the Edelbrock Pro Flo EFI and nickel plated front cover/oil pump. Rotating assembly is balanced, block is blue printed. Heads are next. This poked and stroked 401 (421) is going to generate an impressive amount of torque, very good HP and get fairly decent gas mileage.
jeepsr4ever
Will you be dyno-ing this engine?
Dusty
I hope you dyno it i regret that i didnt have the $$$ or the time to haul my setup back out and dyno it.
Good Luck.
