Harder Quiz

1197cc
10.25:1 compression
KZ Head Only [no J] not that it really matters anyway
Any pipe you like -
Any carburetors you like
Any cams you like
Any ignition you like

You get to pick carbs,ignition, cams & pipe.

Goal is good daily driver with exceptional midrange and strong top end pull. Idle quality must be good and no flat spots anywhere. Just broad, progressively stronger pull from 2000RPM on up.

Two part quiz. For those who want to impress, sort out the first group of questions. For those who really don't have that background, pick the components and forget about part 1. [not trying to be a dink with the hard questions, I know that's not really fair to everyone but what the hell...if it makes you learn something... what did it hurt?

Part 1:

What's the minimal amount of air the engine needs to achieve 120% trapped Volumetric Efficiency at 9000RPM?

What valve size is it going to take to get that?

What is your target mean air speed of the intake port?

What is the required average cross sectional area of the intake port to achieve the mean air speed?

What size throats on intakes ?

What lobe centers on the cams?

Have at it

PS.. I'll bet you there are 2 people here that can solve Part 1

Oh...forgot....and no freaking turbo Jimbo :woohoo:

I'm not feeling well, I think my dog ate my homework...

You said volume but I think you mean flow rate.

At 9000RPM a 1197 engine needs 1 cylinder worth of air per rev, so 120% trapped efficiency will give you roundabouts 114CFM.

More important than valve size is intake runner length and cross sectional area to achieve 120% trapped efficiency. I'll say my intake port is 8 inches long(including carb) and has a diameter of 34mm. That should get me close. I'm sick of doing calculations, you win.

Carbs: BS34, pods
Pipe: Dont care, kerker, whatever.
Cams: 410's on 109 centers
Ignition: Dyna 2000, because its better
Valves: 2mm bigger than stock, why? cause I said so.

I'd like to rise to the challenge but for me, a guy with no experience, this exercise means rummaging through my fluids dynamics books and sorting out dozens of equations for a couple hours, and I'm not in the mood, its Sunday.

You must be laughing your ass off when typing these questions... aren't you... :laugh:

Quiz my ass, this is a final exam... :S

Hell why not just through in the bonus question of what is the trajectory of the Space Shuttle as it renters the earths atmosphere but dogging meteorites @ 10 each the size of a KZ1000 at 500mph.

Damn dude... :laugh: :laugh: :laugh:

Oh BTW, sorry to be so offensive, don't want be a dick and hurt your little feelings.... :blush:

I wouldn't say final exam Dave, but that'd be an average midterm in engineering fluid dynamics haha.

My main question Larry, is what are the equations that you use to identify these things? I suppose mean air speed would have to do with actually filling the cylinder in the time allotted(duration of cam as a fraction of a cycle, divide that by revs to get time). But my main thing would be valve size. What correlation are you using to determine required valve size at a certain lift to get the required flow rate?

88CFM@10" KZ HEAD
Cam Motion Z1 .400" cams @ 106/108 LC
Mikuni RS34 flat slides into CV air box
Mac 4 into 2 exhaust
Kawasaki Electronic ignition

I really wish I could answer...more learnin' to do.

Am skeptical (perhaps wrongfully so) that 1197cc with 10.25 cr is consistent with good daily driver plus good idle and performance throughout entire rpm range, regardless of type pipe, carbs or ignition (properly tuned).

Given 1197cc and a true 10.25 cr, thinking cam design (the milder, the better) would be a critical factor and best effort toward making it a good daily driver.

Am one of the guys that likes getting there fast, but also wants to get back. And don't enjoy worrying about over-heating the engine while caught in traffic. A worry-wart, I know. :lol:

For 1197cc with 10.25 cr, would go with L.C. head port, 29 smoothbores ('cause familiar with 'em, and 'cause OMR doesn't have 'em and is secretly jealous of us that got 'em), Kerker or V&H (whichever baffle ear prefers), Dyna-S (simple wiring and stone reliable). And mild cams (starting with stock grind degreed to stock specs).

Seems like the magnitude of an engine's performance enhancement is often inversely proportional to the distance the owner is willing to race. :lol:

Good Fortune!

T_Dub wrote:

You said volume but I think you mean flow rate.

At 9000RPM a 1197 engine needs 1 cylinder worth of air per rev, so 120% trapped efficiency will give you roundabouts 114CFM.

More important than valve size is intake runner length and cross sectional area to achieve 120% trapped efficiency. I'll say my intake port is 8 inches long(including carb) and has a diameter of 34mm. That should get me close. I'm sick of doing calculations, you win.

Carbs: BS34, pods
Pipe: Dont care, kerker, whatever.
Cams: 410's on 109 centers
Ignition: Dyna 2000, because its better
Valves: 2mm bigger than stock, why? cause I said so.

I'd like to rise to the challenge but for me, a guy with no experience, this exercise means rummaging through my fluids dynamics books and sorting out dozens of equations for a couple hours, and I'm not in the mood, its Sunday.

What :lol: You didn't do yourself a spreadsheet yet... shame on you :silly:

I knew you'd be onto Part 1 like a fish in water You get an A+ and fee lunch all next week in the cafeteria

Haha wicked!

I did do a spreadsheet, how could you tell? I was plugging in numbers like crazy trying to get a runner length and area to give me a resonance at 9000RPM haha. Thats the only way to get above 100% volumetric efficiency as far as I know.

oh great a hard one