Ideally, if you could get everything right, every part would reach end of life at the the same time, and the engine would just turn to dust when its time is up. As a practical matter, parts have unequal lives, but whatever goes out first frags everything else, so it may not be easy to figure out the sequence of events.
Every time someone figures that out, and figures out how to prevent the failure, he goes into business. ... and probably loses his shirt, but the guy who figures out how to make the improved part at a profit, prospers, until the next revolution comes along.
The last major step change was replacing valve springs with something that's called pneumatic, and I think relies on pressurized nitrogen instead of wire in torsion.
Well the funnycar shop I hang out at and store my streetrod lost 4 motors and a rear end in 5 straight weeks. Here is a list of the major parts destroyed or damaged.
destroyed or being repaired:
32 pistons, pins and rings
32 connecting rods
3 camshafts
12 roller lifters
3 crankshafts broken
1 crankshaft repaired
2 new oil pans trashed
2 rebuilt oil pans trashed
1 engine diaper destroyed
4 aluminum blocks sent out for repair
8 heads sent out for repair
16 titanium intake valves destroyed
16 stailess exhaust valves destroyed
4 fire bottles discharged
1 ring and pinion set
1 pair of pinion bearings
1 pinion support and bearing destroyed
20 special ring gear bolts replaced
1 pinion coupler
1 drive shaft replaced
$12,000 lost round money
final bills for repairs not in yet but it looks like about $25-30k.
In the nostalgia FC cars the connecting rods seem to be the biggest problem. These are top quality rods the same as used in the big show cars. The guys are just pushing the edge on detonation too far I think. Some guys are using used parts with unknown number of runs on them.
To answer the question, here are the rules for one of the heavy hitters:
Rods need to be replaced after 10 runs,
rod bolts replaced after 5 runs
all main and rod bearing replaced every 3 runs or sooner.
Crankshafts replaced after 25 runs
ring and pinions last about 25-50 runs
cylinder heads are replaced after 50 75 runs
blower restripped every 6-10 runs
These motor run 8800 to 9500 rpm for 6 sec or less. The data shows the motor is at 6000+ rpm and climbing in about 100-150ms, at 2 sec they are at 8000 and going up.
Over the years it hasn't changed much. Stronger rods allow harder running, 4340 heat treated cranks are stronger, aluminum blocks were a huge improvement, aluminum heads hold up much better than the cast iron ones did, roller cams allow better valve control and higher lift and duration. Just a big circle. Sure glad it's not my money.
An engine comes out. Someone hot rods it (maybe even the factory) and pushes it until it breaks. They find the weak link, then either accept its limits or improve that part.
Once they fix the weak link, someone pushes it harder until they find a new weakest link and so on and so on.
Different types of hot rodding find different weakest links on the same engine.
Regards
Pat
See FAQ731-376 for tips on use of eng-tips by professional engineers &
It depends on the regulations too. The different arbitrary limitiations push the failure points into different places. Coupled crank-block dynamic FE analysis is popular in F1 these days.
bentwings1, I can't think of any advantage that an aluminum block has over iron, except for weight. What are the other perceived improvements Al has over Fe?
What about heat transfer rates from the piston to the rings and the cylinder wall onto our cooling system? Depending on how the block is constructed, directly in contact with our coolant or directly in contact with most aluminum.
What about the rigidity factor when being cast is cost less when we pour FE or AL? Is the weight reduction worth the price in some cases.
I'd say they have slight differences in cylinder wall temps off the top of my head. How many different areas would this effect performance wise?
Probably the biggest single advantaqge to an aluminum block is that when the rods get kicked out the block is relatively easily fixed. The " holes" are called windows. A block may have 4 "windows" for example. Aluminum Blocks are commonly welded.
Next is that these drag race blocks are machined from a solid block of aluminum. There are no water passages. The steel sleeves are well supported top and bottom and are keyed to each other to prevent rotation. It takes a stout slide hammer to remove sleeves. If you burn a piston you can easily replace the sleeve and piston assembly. Sleeves are honed round and pretty well stay that way when installed in the block. It is a simple matter to recondition the sleeve walls with a flex hone. They do a nice job very quickly. Pop the sleeve out flex hone it and clean it and pop it back in...no need to clean the block of the hone mess.
There is so much aluminum in these that they really don't get very hot. This has the effect of lowering the combustion temp and therefore makes detonation less ....so you can run them harder. The vicious circle of racing.
It is easy to change displacement simply by changing sleeve bores and pistons. They come already clearanced for the max stroke so it is just a bolt in right at the track.
As far as weight goes the alum block may be a few pounds lighter than the old cast iron blocks but not much. It still takes 2 people to lift one on to the engine stand.
Cylinder heads are also solid aluminum. It alllows for maximum and optimum ports which are huge compared to the cast iron heads.
Again a damaged head can be welded. While it is not a good idea to try it in the average weld shop you simply send them back to the mfg and say "fix please". They get welded up and remachined. Any damaged parts such as valve seats and guides as well as valves and springs are checked and replaced as required. Not cheap that's for sure but done often.
Most of the new alum blocks come with raised cams so cam to rod clearance is a non issue.
There are no stock parts on these so they are a true race motor.
As far a being rigid...I don't think there is any doubt that the solid aluminum block is more rigid. Even with 4 broken rods poked thru the sides the block remains attached to the chassis. I seen cast iron blocks with the wholes side along with the motor mounts dragging on the ground.
The cast iron blocks used to split thru the crank bores or the top of the cylinder bores would split or they would burn between cylinders. Either way it was the end of life for that block. The alum blocks have spacers that fit under the main bearing so that if you smoke a bearing you simply remove the spacers and install new ones along with a new crank (spare part) If you burn the block you just send it out to be welded.
As far as heat transfer....so far I haven't seen much concern. The rings don't really fail like that. It is usually because a piston get burned and takes all the rings and a rod with it. A hole gets burned inthe piston and the resulting liquid aluminum get blasted to the top of the rod effectively destroying it too.
Pistons get scuffed occasionally but again it is from running as hard as possible. They become consumables. It' why this game is so expensive.....run it once and throw it away. Watch Top Fuel on TV some time. They may leave the bare blockinthe chassis be everything else gets replaced between rounds.
True, but I wasn't necessarily mentioning the heat transfer as a reason for failure. I meant my comment as something to view as one area in terms of differences. If rings were to fail it would be due to production flaw, loss of oil from wall wash or improper break-in IMO. Pre-ignition or detonation don't have to happen for ring failure to happen.
Here is a run of one of the shop cars...Telstar in the left lane in 2010. You can see the rings dieing at about 1.29 of the vid. and right up to the time of launch. Then right at the finish line they really cough. The funny thing is that they continued to run the same rings for several weeks more. They were so bad that the starting line got clouded over on every run. Note that the vid is about 2 min long. This is the average time these cars run. 6 second of full throttle the rest is 2800-3000 rpm idle 8600 rpm final.
These car flush about 12-15 gallons of fuel thru them per run so the cyl walls do get washed. The 60 wt oil is still pretty tough to wash off completely however. 2 minutes in a solvent bath is not enough to wash a sleeve clean.
Eventually the rings were replaced. The face of the 2nd ring was nearly polished smooth so they were gone. The top ring is a dyke ring and hard chrome plated. It is much harder to see wear on these. Actually the sleeve cross hatch was nearly gone so just a flex hone repair and new rings cleaned up the atmosphere nicely. Ironically the car ran a string of 6.00's and 230 that hasn't been matched this year. There are other reasons than rings for this however. It's twin car ran a string of 5.90 and 230 with no smoke before the broken motors came along.
Hmmm then Al would of course make a good crankshaft and cam then.
That is since it is so strong and rigid, and of course its light weight would make it ideal as a high speed rotating member. Cast iron is used to make those parts.
Dicer said " ...since (aluminum) is so strong and rigid..."
I think the reported S&R of the aluminum block results not from aluminum's mechanical properties, but the fact the pesky coolant holes etc are eliminated. Altough generically aLuMiNum might have greater tensile strength and ductility than the non-nodular grades of cast iron, and they both are great friends when a fight starts.
Once again, geometry beats (or significantly augments) material properties.
Tmoose I believe Dicers comment is sarcastic by far there. Block design does have an effect on how the material reacts to stress, look at how many designs exist.
I still believe the ONLY advantages AL has over FE is weight and heat transfer due to the properties of AL especially if we are dealing with a steel sleaved AL block. Also if the cylinders were to be directly in contact with the coolant or not.
Maybe AERA may have something more in depth as far as comparative reasons?
It is a known fact that iron blocks will make more HP than an Al that is in the same engine family. There is a reason for the sarcasm. Iron is more rigid and stronger than Al. Heat xfer = wasted energy. Al makes a great chain saw crankcase, light weight.
Yes indeed. The trick is how to minimize this as much as we can without melting engines therefore improving output. One successful man involving himself in the adiabatic realm. Smokey.
Jim McFarland has an article out in CT's book Advanced stock car engine tech titled 'Cooling for power'. Haven't read it yet though.
