1000 hp marine accert?

Yes Cat does make an 18 liter 1000 hp acert. Yet not an acert as we know it when comparing with on highway engines. They do not run compound turbo set ups or VVA's. The PLE 1000hp compression ratio is 14.5:1. Marine engines have various ratings which determine duration of peak hp depending on factors. The 1000 hp has an 'E' rating - For vessels operating at rated load and rated speed up to 8% of the time (up to 30% load factor). So you would find this engine in a pleasure craft, in most cases.

The 625 ratio listed on SIS is 15.2:1. However a member on another forum with Cat TMI access was saying compression ratio listed there was 17:1. I have personally seen both crowns side by side. The heights are the same, but obviously the 625 bowl is larger. So which ratio it is, not entirely sure.

 

They throw the compound turbos away to get less backpressure.

 

I don't know but because the boost is so high then the backpressure must also be high.

 

Ok...going to bring my lack of knowledge into this...

if then we have a higher compression ratio...higher boost...and more cubic inches....

I see the back psi problem...its a two edged sword...more boost is good as long as you have usable fuel until you reach the point where back pressure is working against your benefits...then you change turbo design to produce the same boost with less work.

why is the accert so much less effecient at producing the same power than the 3406E or any other for that matter?

I'm assuming to keep a/f ratios right the accert would have added fuel to compensate for the extra air....or is the extra air an emmisions tactic?

Is one of the accerts problems that they have already added so much boost and compression that its easier to get to design limits where as the 3406E has alot more wiggle room and produces its power so much more effeciently that there is more room for improvement?

What is it about the accert design that makes it so ineffecient compared to the others?

This is an interesting thread...hope it keeps going. Like to know the original question also about the 625 liners on a rebuild...just like lowering the c/r on an old Ford IDI or Chevy (detroit)...you lower it and you are able to put more boost then more fuel into it and make more usable power alot more effeciently. Engineers back in the IDI days I assume thought compression made power...but lower the c/r and make more power with alot less work and wear on components.

 

Could you not use a different tubine design to produce the same amount of boost but produce it more effeciently? I know this is where the accert wastegate and compound turbos come in...Mr. Haney explained this to me already...but you hear of the backpressure on the accert...why not use a different turbine to lower backpressure and decrease loss of energy?

 

Emissions is all they were worried about with the Acerts

 

acert use high boost and VVA for controling the emissions and more uniform cylinder air charge ,it was never designed for performance alone

 

You want to use as little boost as possible to make the power needed. Mass flow makes power, not boost. Another problem with high boost and high compression is that you must use very retarded timing to keep the peak cylinder pressures low enough, that means that you don't have much time to inject and burn fuel. VVA and others lower the in cylinder pressure, boost you see in the gauge is just a restriction in the intake tract, not the actual cylinder filling pressure.