Just curious, other than pistons, rods, pushrods, and a crank no one really buys.. what other components make up a forged motor?

What kills the rods and crank? High revs pretty much??

 

Yes, high revs, or especially in a boosted motor - detonation.

If you keep the RPMs in the sweet spot and detonation under control then you really have to get obscene power levels that flex the crank and block before power alone would destroy anything.

 

The parts you named are what makes up a forged engine. Installing a bottom end girdle is not a bad idea either.
Detonation is the primary enemy to these engines, revving them to the moon would be next! Bob

 

errr.. left that out...i know that detonation kills'em, but I meant factors other than that.

 

Rod & Crank killers:

Detonation
Lean running
Stupid nitrous setups (there are some smart ones)
Rev too high for material/equipment
Low quality/Old Oil
Let the motor overheat
Low oil
Old equipment asked to do too much

Jim

 

What exactly is detonation and how do you prevent it. Im thinking of running about 6-8 psi on a turbo set up on stock motor and want to keep it as safe as possible until i can forge the motor.

 

Detonation is the pre-ignition of the fuel. For example, if the IAT's are too hot or the fuel you're using has too low of an octane rating, the fuel ignites before it's supposed to... this causes damage to motor components. Sometimes you can hear a ping or a knock, because when it ignites it actually can shake the piston against the walls of the motor. A gas with a higher octane means it takes MORE pressure (or heat) for it to ignite. That's why people use race gas (gas higher than 94 octane, even higher than 91 for the western folks) when they run high boost setups. Their motor is seeing more pressure, therefore the gas need to withstand more pressure.... At least that's my understand of it...

When detonation occurs, the engine has something called a knock sensor (when detonation occurs, it sounds like a ping or if it's bad enough it sounds like a knock). Basically the knock sensor determines when the engine has detonation and adjusts the engine's timing to stop it from knocking. It's called KR. KR is not ok though, because detonation has already occured and the bad has already been done... Detonation has to happen in order for the sensor to pick up on it.

To avoid KR, you want low intake charge temps (cool air entering the motor) so the gas won't pre-ignite. When you get your car tuned, you can either pull engine timing (less power output) or add more fuel to the motor (so there's a better A/F ratio) when the motor is WOT. Or of course you can just use race gas or meth, which is kind of expensive. Meth setups run about $400++ I think, then you can use $3/gal for meth (the best to use) or some cheap stuff alcohol (cheap, but doesn't up the fuel's octane near as much as meth). Oh yeah, and lowering your motor's compression ratio always helps... A lot of FI setups are from 8.1-9.1 CR. Some are a little higher, but they either rely on race gas or are just runnning low boost...

Anyways. I think that covers it... Not guaranting anything is 100% correct, but that's it (to my understanding) in laymen's terms.

 

What is a bottom end girdle exactly? I do a lot of searches and read posts and try to learn as I go along, but I've never really heard one of those... Hell I just found out you need to have crankshaft ventilation when you do high boost setups.. I've never had anyone explain anything to me in person, without these forums I wouldn't know crap.

Have a pic of one?

Crankshaft ventilation: When do you know you have pressure within the crank? what problem come of it? What'll break?

 

bottom end girdle = stud girdle: your block naturally flexes, so adding a girdle will help keep it from flexing too much.

I think it's 'crankcase' ventilation, not 'crankshaft'. With high boost you are going to get a lot of blowby (air getting past your rings) and down into the lower 1/4 of your engine (oil pan, etc) creating a good amount of pressure.

 

Crankcase

But is it just one of those things that you're like, "hmmm I'm probably getting a lot of air down in the lower quarter of my engine, I should think ventilation!" or are there any signs of needing it?

 

You will get more crankcase pressure with any blower/turbo. It's common to blow out the dipstick. You need to add breather(s), a catch can for the oil in the vented air, or some equivalent setup. The pressure is bad for your ring seal and oil control.

Here's part of my solution - the other side of the motor also has the breathers and hose to the catch can:



Jim

 

Speed kills!! High RPMs put the most mechanical stress on your engine. Rod loads are determined by rod and piston weight (or mass) and your engine speed. Rod loads increase exponentially with engine speed, so even a small increase in your RPMs will give you large increases in your rod loads.

 

Here's a good girdle http://www.dmperformance.org/

 

this thread is pretty informative....im getting ready to run a blower setup and didnt even think of the crankcase breathers.... i have heard of oil catch cans, but im not exactly sure how they work - what exactly does it do ?

 

Heat and lack of oiling are easy killers of engines. At a minimum you would want to run a ported (and shimmed) oil pump to increase pressure. You want oil pressure generally to increase 10 psi for every 1000 rpms. You'll find that most low 8 second and faster race cars run dry sumps.

 

i've heard lots of good things about that girdle

 

If it was up to me and I was building a high hp/torque engine where I would think about needing an engine girdle... I would probably just use the money I'd spend on the girdle ($300+) and put it towards a stronger LS2 block.

 

DONT FORGET OIL STARVATION!!!!!!!!!!!!!!

not so much a problem for drag guys, but anyone going around a track needs to think long and hard about it!! road tyres these days give more and more grip! this means high G's in corners are easier to achive and thus increases the likehood of the oil pickup becoming dry! NOT GOOD!

aqusumps help but dont provide a unbeatable solution, that only comes form a dry sump setup! look at the road cars with them these day, Z06, 911 Turbo, etc, etc, etc......

Chris.