Building a K 160 Sport engine to beat a Honda...

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Scuffers
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Re: Building a K 160 Sport engine to beat a Honda...

Post by Scuffers » Tue Jul 30, 2013 3:50 pm

Shug wrote:Keep to facts, keep civil, please don't goad arguments.

The mods have indicated in the past and are very willing to simply delete posts or parts of posts, purely to keep the content in the form of facts. I would very much appreciate if we didn't have to stoop to that to keep the thread open.

It might help if KingK could post images of said simulation software screens showing the claims.

What doesn't help is flat ridicule.
Like I said, best we can hope for is some entertainment....

I (and others) have no need to ridicule as you out it, I think you will find he will do that all on his own. :roll:

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hiscot
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Re: Building a K 160 Sport engine to beat a Honda...

Post by hiscot » Tue Jul 30, 2013 4:30 pm

Simon I found this a very long time ago on a triumph ( cars ) site
any truth to this theory ?


Exhaust Tuning theory is actually fairly simple; it�s all about getting the negative (and, hence, scavenging) pressure pulse to arrive at the Exhaust valve as it is opening. To do this we have to set the pipe lengths and diameters correctly.

The formula for Primary pipe length is:

P = [(850 x ED) / RPM] - 3

Where:
RPM is the engine speed to which the Exhaust is being tuned.
ED = 180� plus the number of degrees the Exhaust valve opens before BDC.
P = Primary pipe length (on a 4-1 manifold), or Primary pipe length plus Secondary pipe length (on a 4-2-1 manifold), in inches.

Generally road engines will require the manifold to be tuned to the max torque rpm whereas race engines will be tuned to work either at max bhp rpm or a speed midway between the max bhp rpm and max torque rpm.

4 -1 manifolds restrict the power band, whereas 4-2-1 manifolds give better mid-range power but reduce top end power by as much as 5-7%.

Generally speaking with a 4-2-1 manifold the starting point for Primary pipe length is 15 inches, thus Secondary pipe length is P - 15 inches. Changing the length of the Primary pipe tends to rock the power curve around the point of max torque. Shorter Primaries gives more top end power but less mid-range, and vice-versa. There is, however, little change in the peak torque or the rpm where this occurs.

Ideally the Primaries should come off the cylinder head in a straight line for around 4 inches before any turns occur.

Inside diameter of the pipe can be gained from:

ID = sq root [cc / {25 x (P + 3)}] x 2.1

Where:
cc = cylinder volume in cc.
P = Primary length in inches.

In some engines it can be useful to have a 'step' between the Exhaust port and the Primary (ie the Primary bore is greater than that of the Exhaust port). This tends to be the case in engines with rectilinear Exhaust ports.

For a 4-2-1 system then, Primary pipe diameter is calculated as above. Secondary pipe diameter is given by:

IDS = sq root (ID x ID x 2) x 0.93

Where:
ID = calculated inside diameter of the primary pipes.

The pipe diameter can be used to change the peak torque rpm � a reduction in diameter of 0.125 inches will drop the peak torque rpm by 500-600 rpm in engines over 2 litres and by 650-800 rpm in smaller engines. Increasing the pipe diameter by 0.125 rpm has approximately the opposite effect.

The total length of the Collector and Tailpipe (to the front of the silencer) should be equal to P + 3 inches (or any full multiple of P + 3 for a road car).

Tailpipe internal diameter is given by:
IDT = sq root [(cc x 2) / (P + 3) x 25] x 2

Where P is calculated as above.

Collector length is given by:

CL = [(ID2 � ID3) / 2] x CotA

Where:
ID2 = diameter of Collector inlet
ID3 = diameter of Collector outlet.
CotA = Cotangent of angle of Collector taper (which ideally should be around 7-8� (certainly less than 10�).

The design of the collector should be such that the inlet pipes terminate abruptly otherwise the tuned Exhaust pressure wave will carry on into the tailpipe and the calculations done to get the negative scavenging wave back to the Exhaust valve on time will all be wrong.
bob

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Gourlay83
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Re: Building a K 160 Sport engine to beat a Honda...

Post by Gourlay83 » Tue Jul 30, 2013 6:08 pm

What a great read, thanks for posting that up.
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r10crw
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Re: Building a K 160 Sport engine to beat a Honda...

Post by r10crw » Tue Jul 30, 2013 7:02 pm

Gourlay83 wrote:What a great read, thanks for posting that up.
Yep excellent post, but what rpm do you tune for?? Mid range or close to the red line?
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mwmackenzie
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Re: Building a K 160 Sport engine to beat a Honda...

Post by mwmackenzie » Tue Jul 30, 2013 7:28 pm

Now thats a really interesting post! Everyday is a school day.. thanks for sharing, interested to see if thats the same formula King K is going to use or if there is another train of thought on this? :thumbsup
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GregorFuk
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Building a K 160 Sport engine to beat a Honda...

Post by GregorFuk » Tue Jul 30, 2013 8:28 pm

KingK_series wrote:
GregorFuk wrote:
Gourlay83 wrote: His Arse ? :)

Hey, lets keep it civil or you know how it will go.

I'm genuinely interested as the figures seem so assured and precise. I'd have expected "in the region of" or "around about", not an exact figure.

Software simulation

so for instance you programme in cam, plenum shape volume, valve sizes, runner dimensions then design an exhaust. then you go back and find out which parameter is the limiting one.

its surprisingly accurate, but much more importantly it does allow you to cut out all the trial and error to find out how to max an engine or in this case where the specification is predefined work out where the limiting element is - and perhaps what it would take to move the curves.

the software shows the limiting factor on a 160 engine is the runner, not the cam, which is a pain because its very difficult to do anything about without not using a VVC type plenum/runner system.

however if you did keep the plenum but were able to change the runner dimensions 240bhp is the result with a 160 cam, provided of course you use a properly tuned exhaust - which no one has ever done, they are all just - "use longer primaries cause that gives better torque and then connect A to B' - but that not tuned,

Tuned is precisely the right primary length, precisely the right secondry length, precisely the right tail pipe length, precisely the right dias and precisely the right collector, volumes, shapes and lengths.

Thanks for that. Just a couple of follow on questions.

Is this commercially available software or your on propriety program.

Given the specs of the engine the software can calculate a theoretical power output. Does the software take any account of the physical limitations of the hardware. i.e Yes given the perfect inlet, perfect exhaust, perfect cam the engine can produce xxx bhp. But in reality the pistons, rods, or crank will give up the ghost long before this theoretical power is reached. Surely the engine you are building is going to be limited by what the weakest component can handle?

Once again, I'm asking out of interest.

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philthy
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Re: Building a K 160 Sport engine to beat a Honda...

Post by philthy » Fri Aug 02, 2013 2:43 pm

mentions on post no.1 that it will be using his own design pistons and rods. The standard crank will be able to handle 350+ no doubt.
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robin
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Re: Building a K 160 Sport engine to beat a Honda...

Post by robin » Fri Aug 02, 2013 3:12 pm

Re: Gregor's question on what is the limiting factor.

Not putting words in anybody's mouth but the limitations that are being discussed in this context are gas flow limitations. Of course if you design an engine that can consume enough air to make 300BHP at 10,000RPM then you had better make sure the pistons, rods and crank are up to the loads that places on them.

Re: What RPM to tune for - totally up to you, as the article suggests you will want to consider the application the engine is targetted at; that said it's likely that to obtain the maximum headline power figure you would tune for max RPM as power = RPM x torque, so for top trumps victory you want max possible torque at max RPM.

Given the car that is the subject of this thread is probably not going to spend much if any time on track I would think the most satisfactory result will come from improving torque in the 3K-5K or so band as that's nice revving on the road.

Cheers,
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Sanjøy
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Building a K 160 Sport engine to beat a Honda...

Post by Sanjøy » Thu Nov 14, 2013 8:53 am

Any update on Stu's car as Tut mentioned elsewhere?
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Stu160
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Re: Building a K 160 Sport engine to beat a Honda...

Post by Stu160 » Thu Nov 14, 2013 9:49 am

No , nothing yet.
Its been a busy year at work, and the 211 has had all my spare attention ;-)

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Re: Building a K 160 Sport engine to beat a Honda...

Post by KingK_series » Thu Nov 28, 2013 2:26 pm

Stu160 wrote:No , nothing yet.
Its been a busy year at work, and the 211 has had all my spare attention ;-)

Stu

Hey Stu

- I'm into the new house, now got to set up the new workshop.

Anytime you sort out the short end of this engine, give me a bell - I have to send you a new address.


Head is ready for you to skim.

Scuffers
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Re: Building a K 160 Sport engine to beat a Honda...

Post by Scuffers » Thu Nov 27, 2014 8:37 am

Another year has passed...

still no signs of any all-conquering K-Series...

Guess it will all be in the mythical book...

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Stu160
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Re: Building a K 160 Sport engine to beat a Honda...

Post by Stu160 » Thu Nov 27, 2014 9:14 am

No , my fault, very busy at work, so still on hold.
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Re: Building a K 160 Sport engine to beat a Honda...

Post by KingK_series » Mon Dec 22, 2014 1:14 am

Stu160 wrote:No , my fault, very busy at work, so still on hold.

One beautiful head all ready Stu, cams REM finished, plenum and runners prepped, all I need is the parts for the short end and we are away...

,,,, be really great to get this one going soon.... it's taking space on the bench for so long now..

happy christmas!

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philthy
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Re: Building a K 160 Sport engine to beat a Honda...

Post by philthy » Mon Feb 23, 2015 12:36 am

Any further forward with this? Popped into my head today for some reason
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