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Matt Worrad
Tinkerer
NSW/VIC
Wanted TT

Posts: 10
Reg: 05-2006

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Wednesday, May 31, 2006 - 06:08 pm, by:  Matt Worrad (Mworrad213) Quote hilighted text Edit Post Delete Post Print Post   View Post/Check IP (Moderator/Admin Only) Move Post (Moderator/Admin Only)

G'day everyone,

Just wondering if anyone would like to help me with my assignment. I have some questions which need some reasonably qualitative responses. They are as follows:

1. In what ways can an engine be made stronger?(able to withstand higher loads, compression pressures and revs)?

2.How can you make an engine rev more freely?

3.Why do Extractors or headers usually produce a power gain over normal exhaust manifolds?

4.What are the advantages of forged pistons in a race engine?

5. Cylinder head porting can be a complicated and risky task but can be done to vary degrees. What is meant by match porting?

6. Briefly explain what the process of "cc-ing" cylinder heads?

If anyone can help me out with anysort of information it would be greatly appreciated.

Cheers, matty
Tim Appleton
TryHard
QLD
Soarer UZZ31 V8 GT-L

Posts: 149
Reg: 07-2005

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Thursday, June 01, 2006 - 07:47 am, by:  Tim Appleton (Timbo) Quote hilighted text Edit Post Delete Post Print Post   View Post/Check IP (Moderator/Admin Only) Move Post (Moderator/Admin Only)

Ok, I'll give this one a shot. Anyone, please correct me if I'm wrong.


1. a) Usually involves improving the bottom end of the motor. Stronger crank bearings - 4-bolt, or 6-bolt cross bolted (like a 1UZ-FE), Honda use cradling (all bearings form one cradle that bolts to the bottom of the motor).

1. b) Stronger crankshaft (usually improved metallurgy, and heat treatment).

1. c) Stronger conrods - thicker section conrods, shot-peened H-beam rods such as Carillo's (spelling?) are the ducks guts.

1. d) Stronger pistons - forged.

1. e) Stronger bolts/studs.

2. a) Making an engine rev more freely involves lightening moving parts and stopping the valve-train from bouncing. Lighter conrods and lighter pistons will have some effect, but strength may be an issue. The valve-train usually need to be lightened/improved ie. titanium valves, stiffer valve springs to handle the increased velocities that the valves will see. If increasing revs then an undersized pulley is usually recommended for the water pump so it doesn't cavitate.

2. b) The bore/stroke of an engine will also affect the free-revving nature of an engine. A bore that is larger than the stroke allows more area for valves in the head for a particular displacement, therefore allows more air/fuel mix into the head at higher engine revs. A bore that is smaller than the stroke (stroker engines) have less area for valves in the head, so are likely to flow less at high revs, thus are suited to lower rev-range tuning. F1 engines, which are the highest revving piston engines in the world (as far as I know), are essentially very short stroke, large bore engines.

3. Normal exhaust manifolds are usually designed with mass production in mind ie. to allow someone to bolt it on easily in a factory. As a result they are generally not very efficient at letting exhaust out of the engine. A set of headers will generally be more free flowing and of larger diameter. Tuners can also create headers that are tuned length. When two or more runners join into one, and there is a pulse from one runner, then it sends a negative pressure wave up the other runner. If this reaches the exhaust valve at the time that the valve opens then it effectively sucks exhuast out of the engine, making it more efficient.

4. Forged pistons in a race engine are used due to durability. The forging process creates a stronger, more durable metal due to improved grain structure by dislocation of grain boundaries in the metal.

5. Match porting is when all ports are flow tested to flow exactly the same. This can create a very balanced engine.

6. I don't have a full understanding of cc-ing, never seen it done. Just a way of measuring the volume inside each combustion chamber (i think), so that compression ratio can be calculated.

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