Defining VE in this manner (referencing In Man conditions) means you cant do meaningful development work on the intake system upstream of the intake manifold. I've seen folks use this method (usually very academic types who have no real world experience developing real engines) and then pat...
RodRico, thanks for the plots, unfortunately it combines engine friction with thermal losses.
What would be more useful would be to show indicated thermal vs engine cylinder size that doesn't include the frictional aspect.
In all the Annand and Woschni models I've tuned to MEASURED single...
I cite direct data based on engines I've developed and my experience. Yep, I go to the trouble. I wish I had the balls to cite data from a book I barely remember and cant prove when the burden of proof is on me. Magnificent!
Oh, and the reference is wrong, I checked.
Oh well
"Do not argue...
The limit to petrol down sizing seems to be about 300 ccs.
The benefits of the smaller size and 'de-throttling' for lower pumping are offset by the greater heat loss from the cylinder.
This is reflected in the BSFC.
From the example I outlined above: "From my database and experience on a...
"Diesel efficiency increases with cylinder dimensions in all practical sizes.
SI efficiency plateaus and falls when cylinder dimensions exceed some (much smaller) value."
This is very vague.
Where and how does SI efficiency FALL or drop with increasing cylinder dimension?
Are you talking...
Jag engines (This includes the old AJ16 straight six and the V8s) where subjected to thermal shock tests- where at full operating temperature and high load the engine was flushed in the dyno with coolant suddenly at -20 deg C to test the integrity of the cylinder head gasket.
Other established...
"Do you see the contradiction? "Bigger" has a limit.
As SI cylinders get larger you reach a point where flame path gets too long and efficiency must suffer - unless you can provide multiple ignition points."
There's no contradiction - only a trade off.
And this is often somewhat overstated...
Bigger cylinders are more efficient in both diesels AND petrols.
This is due to lower surface-to-volume ratio and therefore lower heat loss.
The effect of this is better BSFC. From my database and experience on a petrol when the cylinder size reaches about 500 ccs, you get good best point BSFC...
"The Bimmers use caster offset as well as caster to accomplish their steering feel goals. I'll let you guess what their knuckles/uprights look like. This can make front driveshaft action quite a mess if you also desire 4wd."
They probably do that to reduce mechanical trail.
"You need to know...
Cibachrome, thank you. I do actually prefer the E46 over the E39 as more of a sporty car but the E39 R and H to me is great as a daily driver on these dreadful roads.
Thanks for the info on the vbox or the yawrate gyro- I'll certainly look into it.
I had a friend who worked at COnti, I'll dig...
Hello everyone I have a desire to have my (1998-2002) X308 XJR ride and handle like an (2000-2005) E39 BMW M5. Let me preface this by saying that I’m NOT interested in buying an E39 M5: The Jag stays, I love the looks and style of the Jag and it represents a special time for me- from when I...
I have been digging deep into vehicle dynamics in general and Roll centres inparticular.
My OEM background has had me deliver various vehicle projects where Ive had a good overview but Im now digging in technically deeper. I intend to learn and also apply these learning to various project cars...
BMW used a two piece cylinder head split along the axis of the cam shafts on their first Euro S50 M3 engine (286 bhp version not the US anaemic joke 240 bhp version) and this was in production.As far as I know the structure presented no problems but the later evolutions (the B32 S50 and S54) got...
I think it's good that the original poster is trying to reference some theoretical theories when sizing up plenums.
In practice, these along with some of Vizards relationships I have never really found to work definitively.
The guidelines I've developed over the years include:
• 20% bellmouth...
We ran an Indian Thunderstroke 111 with no oil pump/minimal oil supply as a durability test.
It ran for a quite a few hours, lifters clattering away, with no lube, but it ran, very high temps in the pan.
That engine is indestructible!
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For a military application where high specific output is a priority along with compact size, and less heat rejection to coolant (the Opposed Piston engine tends to reject more heat to exhaust than coolant). Its no surprise its been selected. The military doesn't require particularly high...
Hi Hemi, how are you?
I agree, Ive often seen ego-centric 'larger than life' characters starting up these Start up companies who schmooze the VC companies and bowl them over. Unfortunately , good engineers are more often than not more data driven, balanced, transparent with less emphasis on...
Achates makes some heady claims. The fact - they have been twisting the truth using selective data and massaged simulation data for so long. When they finally had hardware they found the bsfc achieved was no where near what they claimed. The issue was- their cult like atmosphere - where anyone...
In my experience Nicasil was a big issue when there was high sulphur content in fuels. In terms of friction Nicasil vs iron liner- below 8500 rpm there is very little measureable difference in the real world. Once you start to rev to 10,000 rpm then there frictional differences become more...
Radek it IS possible that the torque dip at 4000 rpm is due to this. The way to be surer is to not look at torque but at volumetric efficiency (you can calculate it from the fuel flow and air flow ratio). A dip in torque can be due to ignition or a due to excessive knock limit etc or due to...
