|02-29-2012 10:34 AM|
these are engineering texts rather than popular press editions so without some engineering background they can be a somewhat more difficult and certainly dullish reads, but when you gain an understanding of the rocket science below the surface you can connect the results seen in the popular press with the scientific whys or why nots that cause things to happen the way they do.
There are older books by Smokey Yunick and Bill Grumpy Jenkins that include useful though often dated information, they are very useful in building a perspective about how we've come to where we are in what I refer to as the modern performance era which starts with the OHV V8 designs of the 1950's to the present. If you add some books like "Allied Aircraft Piston Engines of World War II" by Graham White and "History of Aircraft Piston Engines" by Herschel Smith you'll see the connections in design and materials to modern automotive engines and learn that things like nitrous injection, super charging, cross bolt mains and crankshaft girdles have been around for a long time where the need for high power, strength and light weight have been driving design solutions. In many ways the automotive field is just catching up to the structural and material technologies of WW II aircraft engines so these books and others provide a useful perspective. Of course we have titanium that wasn't available as a useful material in the 1940's but that aside most everything in these airplane motor books will look familiar.
By the time you build a good library you'll spend a lot of money but it's worth it, knowledge is power.
|02-28-2012 07:49 PM|
Take a look at a few titles from HERE.
|02-28-2012 05:31 PM|
A 4 bolt block adds time between crank and main cap failures, the extra attachment in the center of the block is designed to deal with the unbalanced forces that are trying to bend the crankshaft around the center main. This puts a lot of load on the number 2 and 4 main. Short of adding counterweights opposite these center throws there isn't a lot that can be done to lower these forces. And that doesn't eliminate them, it reduces them but at the expense of adding considerable weight to the crank which then causes a list of other problems.
Rods and pistons are the weakest link. Factory Chevy rods be they forged steel (including the pink) or powder forged are pretty reliable for a hot street engine into the max output range of 400-450 hp. For circle track you might get them to deliver 500 pretty continuously, for a steady diet of drag racing probably anything beyond 350-400 is treading onto thin ice. Getting up above 420-450 especially if drag racing the engine you need to look to better rods with better bolts and designed for full floating pins. I beams work well into the 500-600 horse range, above that you must look to H beams in steel. Titanium can push the I beam further or use other configurations here's a site where the sucking sound you hear is you VISA card being emptied but shows a different beam shape http://www.pauter.com/billet_rods.htm. Aluminum rods tend to stay with the I beam shape but that as much as anything is a fluke of the material and the processes that can be used to make them.
The block will put up with a lot more, most failures of the block occur where the rod went through it. But when you start pushing 500 and more depending on how hard you beat the block it will start showing fatigue cracking usually around the cylinder ends into the head deck and/or into the crankcase. Another common cracking location is the cooling jacket walls that form the sides of the lifter valley. Always remember that for every action there is an opposite and equal reaction. So, for example, the force pushing the piston down the bore is with equal ferocity trying to blow the head off, expand and stretch the cylinder bore, etc.
High power outputs are hard on the pistons, pin and small end of the rod, there's lots of heat and risk to grabbing the pin so you have to change to better pistons, cast especially hypers are about at their limit getting into the 400-425 hp range, you've got to look to forgings. Again there are forging and then there are forgings. these compared to cast pistons range from expensive to ungodly expensive. this is where the rod needs to become a full floater for the pin, so if the pin gets trapped in the piston there's someplace left for movement without tearing the piston apart.
Detonation is your enemy, it not only takes out pistons but rods and cranks as well. At any power level this must be addressed but at high power settings it can destroy an engine before you even hear it. Piston crown and combustion chamber shape are big time players. Flat tops, D dishes and Ricardo (called Fastburn, Vortec, GT40, Magnum and others by various makers) chambered heads let you push the limits upward on compression. Compression needs to be computed in Static and Dynamic ratios. The cam timing events establish what the dynamic will be, generally looking to hit a range from 8 to 9 to 1. The Static has to be adjusted to hit the dynamic desired.
Lubrication in a high performance engine is a huge issue. Here there are "forces" that are in opposition like no other place, you want a lot of lube but not too much. The pump output varies with engine speed, it's easy to have too little at low speeds and way too much at high speeds. Too little starves the parts and bearings will suddenly let go, too much and you're wasting power driving a pump that's on excessive bypass, bypass heats the oil without it performing it's cooling function in bearing clearances reducing its viscosity potentially to the point of film failure. It eats too much power to do this which comes off the crankshaft while serving no useful purpose. The excess oil floods the rings which increases the amount carried into the combustion chamber where it reduces the fuels available octane resulting in a detonation prone engine which we already hammered on. Yet if you must error on oil, it's probably safer to deliver too much than too little. For a wet sump engine that means a lot more attention needs to be paid to wind-age trays, crank scrapers and trap doors in the pan than is usually considered by the average hot rodder.
So in the end there is an old saying, Speed Costs Money! How Fast Can You Afford To Go?
|02-27-2012 09:39 PM|
|Blazin72||The best thing you can do is set a realistic goal of what you are looking for here then ask questions that pertain to that goal. It's pretty safe to say that at 17 you aren't going to get 515hp to the rear wheels on your budget so just forget about that one. 350 to 400hp+ is easily doable with a 383 and the best thing you can do is use that big white search bar at the top of each page and read similar threads and questions that have already been asked. Probably the two most common engines talked about on here are 350s and 383s. There is more than enough information to answer almost any question you will probably come up with. It just takes time to read it. If you can't find the information you are looking for then by all means, ask.|
|02-27-2012 09:29 PM|
|cherrynova||To be honest I'm ur typical 17 year old with a. Billion ******* questions and end up making myself look like a Moron lol|
|02-27-2012 09:26 PM|
|cherrynova||To be honest I appreciate you telling me the truth. I'm sorry if ive ticked anyone off|
|02-27-2012 09:23 PM|
|Blazin72||I'm not going to call you a moron or make fun of you in any way here. What I am telling you is to think about what you are actually wanting instead of coming on here and telling people that you're building four different engines within the space of a few days. It's fine to ask questions, just don't send people on wild goose chases. You won't get a lot of help that way.|
|02-27-2012 09:21 PM|
|cherrynova||All I want is to learn. Just please help me out with all my questions I know its annoying but I'm working with what I know|
|02-27-2012 09:16 PM|
|cherrynova||To be honest dude I'm not sure I'm looking at different things and combos im still looking into the supercharger route in the future that's why I'm asking different questions. And am having to think about "temporary" builds. Feel free to call me a Moron lol but I'm mainly looking for a street car to keep up with stangs and camaros and run off pump gas|
|02-27-2012 09:10 PM|
Time out here. What are you looking for? A few days ago you were wanting a 515 rwhp supercharged 383, then it was a 365hp 383, then a 350hp 383, then you were looking at buying a 383 from Summit. Now you are wanting to know about making a "max amount of horsepower without forgeing everything". Stop messing around and give people a reasonable expectation of what you want here.
Pick one and stick with it....
|02-27-2012 08:59 PM|
should i forge my block?
Hey guys ive got an ole 4 bolt main sbc 383 I'm looking at building up just give me a good Max amount of horsepower I should be allowed to have without forgeing everything. Thanx guys