k series engine information

[mxmaz]

klde is the most boost friendly with lower compression ratio of 9:2:1. kfze im pretty sure has 10:1 cr. along with the klze.

[babyblueMX3]

not a kfze guru but I thought it was 9.5:1

[Custommx3]

KFZE is 10:1

[babyblueMX3]

well the first like posted above says that the kl is 9.2 kf 9.5 and k8 9.2 and it doesn't look like a gettho site or somthing

[mxmaz]

would the k8ze have 10:1 compression ratio as well

[Gro Harlem]

yes

[mxmaz]

Originally posted by babyblueMX3:
well the first like posted above says that the kl is 9.2 kf 9.5 and k8 9.2 and it doesn't look like a gettho site or somthing

Yeah seems like a reliable site. I'm thinking its talking about de engines models not ze

[Kokiriwave]

Compression stands for what exactly? 10.1, 9.5.1, 9.2.1. What does it mean, how does this discribe the engine. What is high compression/low compression? Boost is easier on lower compression engines? why?

[Gro Harlem]

its simple. Compression is the measure of air density at the bottom of the stroke as compared to the top.

basically take a cylinder...measure how much displacement it is at the bottom of its stroke and then the displacement at the top (when the plug fires & ignites the air/fuel mixture) and you have your compression ratio.


Lower compression is good for turbo b/c more volume of air can be forced into the combustion chambe resulting in larger power potential. Of course you need more fuel to match the air/fuel ratio, but that is why ppl with boosted motors prefer lower compression.

[perhapsadingo8yerbaby]

Originally posted by Kokiriwave:
Compression stands for what exactly? 10.1, 9.5.1, 9.2.1. What does it mean, how does this discribe the engine...

Compression is expressed as a ratio i.e. 9.5:1, 9.2:1, 10:1. It's the ratio (relationship, 10-to-1) in a single cylinder of the maximum and minimum cylinder volumes measured when the piston travels to the extreme ends of its stroke. So, volume of one cylinder when the piston is at the bottom divided by the volume of that same cylinder with piston at the top of its stroke = compression ratio.

Think of it this way, if you have an engine with a 10:1 (10-to-1) compression ratio:

When the piston is at the top of its stroke, the air/fuel mixture is compressed by the piston into a tiny minimum volume of space in the cylinder and that value is always assigned as "1".

When the piston is at the bottom of its stroke, the air/fuel mixture enters the cylinder into a volume of uncompressed space that is 10 times larger than when that volume of space is fully compressed by the piston at the top of its stroke = 10:1 compression ratio.

Here's a pic of the compression process. Maybe the visual will help along with the explanation. http://auto.howstuffworks.com/engine3.htm

There are ways to increase your compression ratio. For a normally aspirated engine, the higher the compression ratio, greater the Hp produced. However, in a turbocharged set-up you don't want so high as a normal/high compression ratio because you're now turbocharging. Think of it as the turbo "pre-compressing" the air/fuel intake charge by jamming it into the cylinder. Having a too-high CR along with a turbo can cause the air/fuel mixture to be under such high pressure under the piston compression stroke as to detonate before the plug sparks- pre-ignition - always a bad thing.

Super high compression causes similar detonation in the way a diesel operates and there it's a good thing, diesels are designed to be very high compression and use glowplugs instead of sparkplugs. In a gasoline engine though, detonation can destroy the engine or require such a high octane (octane prevents early detonation) that you'd need gas additives to run. With too-high CR and Turbo, even if you solve the detonation prob, your engine internals might not hold up to the tremendous forces in your engine. Can blow a head gasket that way.

So an engine that has sturdy enough internals to be turbo'd can also handle more turbocharging if it's a lower compression ratio, rather than higher compression ratio engine.

<small>[ November 12, 2004, 06:09 AM: Message edited by: perhapsadingo8yerbaby ]</small>

[Reaver19]

Can a full engine swap (K8 to a KLDE) be done in one day, assuming nothing has been prepared the day before (engine still in the car, etc)? Does the KLDE engine swap run better if you have the K8 ECU in with the KLDE VAF or better with the KLDE ECU and KLDE VAF?