how performance car parts influence torque vs horsepower?


by hondaman520
Tags: horsepower, influence, parts, performance, torque
xxChrisxx
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#19
Feb24-12, 08:15 PM
P: 2,032
its late and i've been out on the beerr.

but we all have a differnet breadth of knowledge to bring to this foruim. and that what s makes it so great.
jim hardy
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#20
Feb24-12, 08:22 PM
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Isnt this what led to the jet engine ?

In WW2 turbochargers increased mass flow rate to point valves got in the way, and thrust from exhaust became significant? Since the recipcating engine was becoming almost a compressor/heater for the turbo they replaced it with centrifugal compressor and burner cans.....

i've read that the air-racer guys run their P-51's at 4 atmospheres..... i dont know if thats a lot but sounds like it to me.

old jim
Pkruse
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#21
Feb25-12, 07:53 AM
P: 490
I find that very interesting, Jim. I wonder where I can learn more about WWII applications. In all the research I've done on the subject, I've seen nothing. Apparently, I'm looking in the wrong places. I know a man who has been designing turbomachinery since WWII, and his mind is still extremely sharp. I've got a meeting scheduled with him next week to talk about some engineering design software he has developed, and to compare it to my feeble attempts to write similar software. I'll see if perhaps he can add something interesting on the subject.
jim hardy
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#22
Feb25-12, 08:25 PM
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I hope you bring back some anecdotes.

Dover Press used to have interesting old technology books.
Their "Aircraft Carburetor" book should be in every high school curriculum . Nobody should be helpless when confronted with a gummed up lawnmower or outboard.
Pratt-Whitney puiblished a wonderful "Aircraft Magneto" book, i wonder if it's on their website....

I'll poke around.
Fahlin Racing
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#23
Feb26-12, 08:10 AM
P: 89
So you want to study the structure of an engine. First off you should be observing your foundation. The cylinder block/ engine block. You will have engines that utilize parent bores or sleeve/liners (mostly diesel mills). Besides the two apparent large reasons we have being used today, a block is a block IMO, doesn't matter who cast or cnc milled it. Look at every area of the block, some have ribs, others are just thick cast etc. What you are really looking at is how the block maintains its shape and rigidity through design while enduring the stresses of operation. You do the same observations with the internal rotating assembly. Other observations you need to consider are your lubrication clearances, gasket thicknesses, engine coolant passages, top end layout (head(s), intake manifold position and layout. The internal dimensions of everything play roles from cooling efficiency (heat transfer) between your oils and coolant, lubrication efficiency, strength to keep distortion at bay (look at fasteners too) and so on. You can build an engine ANY WAY you like, its the hood of the car or truck that limits us from making the most optimum design possible. The engine is a big compromise plainly put.

I wasn't sure about compression, because I know compression is wanted as much as possible in order to burn ALL the fuel in the cylinder, and diesels can withstand more compression due to their durability.
Lets clear this up some. You can use compression for two things I think are worth speaking of, one is obviously producing a ratio large enough to propel the vehicle efficiently. Two, using it only to make as much power as possible without burning completely in a gasser engine. If you can get more torque/power from higher compression and you don't have to worry about a 100% complete burn, without washing your walls, it will make your vehicle fast only IF your suspension can plant the tires. In the diesel's perspective, you have a big difference in combustion characteristics. First, being your fuel, the diesel fuel has more energy to release because of being more dense. Second, you have compression ignition which the lead point (starting of injection) is what you could call diesels version of spark timing. CI engines use less lead reducing work lost to pressure buildup prior to TDC. Depending on the diesel, you will notice the chamber design in the crown of the piston. Same for any gasser mills. I guess what I am saying, compression is not the only factor when attempting to produce a complete, clean efficient burn.

It is understood that more air+fuel at 14.7/1 ratio you can get in and out of an engine, the more work will be done.
Stoichiometric (chemically correct) is a baseline for the perfect burn. Depending on your chamber characteristics and fuel and fuel amount and numerous other variables contribute to a complete burn. Thermal efficiency and combustion management will be what you should read on not only car engines but motorcycle engines from early to modern time. Sir Harry Ricardo, Jim McFarland and Larry Widmer are a few people you should check out.

My advice for you, buy books not just the ones you need for the engineering course but actual performance books. David Vizard has some good ones, Charles Fayette Taylor, Reher-Morrison racing engines and many others. Understanding how engine parts are machined and assembled will give you a good base to start from. Be careful on what you read, there is a great amount of BS out there or its just a big advertisement for the company its involving.

Get an engine, right now still being the cheapest will be a SBC unless your already have an engine in the garage. Take it apart and BUILD it don't just assemble it. If you thoroughly build an engine for a goal you present to yourself you will have learned something. Putting something together is just that. Building something is tayloring it to your preferences on what you want it to be.

The structure of each part of the engine when compiled either produces efficient power or you have junk. Building an engine will teach you alot on what you are trying to learn.
mender
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#24
Feb26-12, 01:06 PM
P: 563
Quote Quote by Pkruse View Post
Mender:
All he knows is that he and his friends have broken Chevy cranks, but they don’t tend to break the Dodge cranks.
They shouldn't be breaking cranks at only 1400 hp; there are cranks out there that will handle 2200+ hp - if they don't rattle the engine.

Heck, even a stock cast crank (and block and rods and pistons and rings and bearings!) in a 4.8 LS engine can survive over 1200 hp.
http://www.hotrod.com/techarticles/h...g_bang_theory/
Quote Quote by Pkruse View Post
Mender:
These pistons passed all those tests with me, but the real clincher was when I checked the literature that came with the parts, which said that they were indeed made out of Titanium. Titanium may be very rare for pistons in a SBC, but they are available.
I stand (well, sit, actually) corrected.

But as with the Dodge crank in a SBC, it seems like an unjustified expense. Maybe your buddy should go buy a junkyard LS for $500 instead!

Quote Quote by Pkruse View Post
But then I’ve already been told that folks who make cars go fast go more on the gut than on science.
The ones that make them go the fastest use science. :)
Pkruse
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#25
Feb26-12, 05:18 PM
P: 490
Sorry. I must have made a typo or something. That was just shy of 1400 hp. Not 1400 rpm. He was spinning that thing very fast, but I forget how fast.

These were race egines for airboats. They are not real boats, more like skid pans running in a couple of inches of water for a short drag race. I'm told that the hulls are 200 pounds or less, but all the rigging that supports the engine must add significantly to that number.

The real innovation was a light weight compact gear box, that enabled the use of automotive engines rather than aircraft engines, and which lowered the height of the engine significantly to keep the CG low.
mender
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#26
Feb26-12, 10:02 PM
P: 563
Quote Quote by Pkruse View Post
Sorry. I must have made a typo or something. That was just shy of 1400 hp. Not 1400 rpm. He was spinning that thing very fast, but I forget how fast.
No typo; also no previous mention of the rpm, engine size, boost or amount of nitrous being used.
Quote Quote by Pkruse View Post
A friend builds up Chevy small blocks to put out nearly 1400 hp.
Quote Quote by mender View Post
Quote Quote by Pkruse View Post
Mender:
All he knows is that he and his friends have broken Chevy cranks, but they don’t tend to break the Dodge cranks.
They shouldn't be breaking cranks at only 1400 hp; there are cranks out there that will handle 2200+ hp - if they don't rattle the engine.
Why would you think that you made a typo?
Pkruse
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#27
Feb27-12, 06:54 PM
P: 490
Thanks for the info. I had no idea that you could buy a shaft that strong. Any idea as to how it is designed for such strength?
Pkruse
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#28
Feb27-12, 07:03 PM
P: 490
Reminds me of a mobile crane that I was responsible for maintaining years ago. It had a Cummins V555 engine. The crane broke. It did not have many hours on it, but it was out of warranty. Our procurement department could not find a source for a new crank, so I called up to find out price and lead time on a new engine. They informed me that they quit making the "triple nickel."

I asked, "Why."

They said, "It kept breaking crank shafts."

So we replaced it with another engine, I think that was a Cummins C-series. The other option was a Detroit Diesel 2-stroke, but we really did not want another one of those. Not for an engine that spent a great deal of time at idle speed.

That was not the only broken crank we had to replace in many different engines over the years. I've always wondered why crankshafts sometimes break when they had not been overloaded.
HowlerMonkey
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#29
Mar1-12, 10:03 AM
P: 275


Everything else you might need can be found here.

http://www.bookfinder.com/author/pet...shing-company/
Pkruse
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#30
Mar1-12, 06:50 PM
P: 490
I've learned a great deal from you guys, now it is time for me to return the favor.

We had talked about how a reciprocating engine with a turbocharger is much like a gas turbine, if you consider the engine to be the combustor. You then have a compressor feeding a combustor feeding a turbine, just like in a gas turbine. That led to a discussion of the use of turbochargers in WWII aircraft, and speculation that the turbine exhaust may have actually provided some thrust, making it in effect the first use of a jet engine. I mentioned that I would have an opportunity to learn more and was encouraged to do that and get back to this discussion thread. I’ve learned more, and this is the result.

Airplane designers tended to favor the mechanically driven air pumps we call a supercharger today. This was especially true of the smaller aircraft like the fighters, because with existing technology at the time that could be fit into a smaller package. But some of the fighters with wider fuselages were fitted with turbochargers. The larger planes, like the bombers, were fitted almost exclusively with turbochargers. At the time, the pilot had a very complicated task when flying with a turbocharger. He had to simultaneously adjust throttle slowly, while making adjustments to the waste gate to maintain proper manifold pressure. This could seriously task load the pilot in combat, which was another reason they preferred the superchargers. They still had to make adjustments, but apparently it was easier and less critical with the technology at the time. This was not a big problem for the bombers. Of course, all planes required some sort of boost to attain the altitude they desired into the thinner air. Boost pressures were very high, but that was controlled with the waste gate. They used very little boost when at low altitude, and often none at all. I was not able to confirm what the maximum boost pressures were, only that they were very high by today’s automotive standards.

The development of superchargers started during WWI. Two companies who got an early jump on it were GE in the USA and Roll Royce in the UK, about 1917. GE was the first to develop an exhaust driven supercharger, for which they coined the name “turbo-supercharger.” That was later shorted in popular jargon to “turbocharger.” But we all need to remember that technically a turbocharger is a type of supercharger. GE developed a number of high temperature super alloys for use in the turbocharger that are still used in jet engines today. It was because of their dominance in the production of superchargers that they were the obvious choice to select to develop the first operational jet engines in the USA. Roll Royce followed a similar path in the UK. GE actually had a contract to develop a jet engine, but when WWII started the government shut that down because they did not want to pull resources away from the production of turbochargers, which were critical for the war effort. Then later in the war when England was getting blasted daily with bombs, they sent Whittle and his engine to the USA for safety, and GE was selected to help him develop his engine into something useful. After the war, the German inventor of the jet engine, Hans Von Ohain, joined the effort. This accounts for GE’s early dominance of the jet engine market after the war.

Perhaps the turbo exhaust in the WWII aircraft did at to the thrust, but the amount of this thrust was so small in comparison to the thrust of those monster propellers that we can ignore its contribution. In this, they were more like modern turboprops. With a pure turbojet, the turbine only pulls out enough energy to run the compressor, which leaves a great deal of exhaust energy to provide the thrust. The exhaust provides all of the thrust in a turbojet. But a turboprop or a turbofan engine is different. Those turbines are designed to pull the maximum amount of energy possible out of the exhaust, to drive both the compressor and the prop/fan. The prop or the fan provides nearly all the thrust, while the jet exhaust provides very little thrust. The same was even more true of the WWII aircraft. The idea was to provide as much energy as possible to those very large propellers, and they provided the thrust. The exhaust flowing aft provided essentially none of it at all.
HowlerMonkey
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#31
Mar1-12, 08:34 PM
P: 275
Then you have the napier nomad I.

HowlerMonkey
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#32
Jul11-12, 09:29 AM
P: 275
The easiest thing to do is pick a platform to use for your learning and go to forums used by the guys who are hopping up said platform.

It's easier to learn on something that will stay familiar throughout your studies.

Once the physics behind it is understood, you can move laterally through different makes/brands.


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