Go Back   DIY Go Kart Forum > Building Plans And Advice > Engines & Clutches

Notices

Reply
 
Thread Tools Display Modes
  #21  
Old 02-24-2020, 08:51 PM
karl karl is offline
Senior Member
 
Join Date: Feb 2011
Location: North east Ohio
Posts: 1,564
Thanks: 125
Thanked 337 Times in 272 Posts
Default

Quote:
Originally Posted by Kartorbust View Post
Not exactly what I meant. I never looked, but I haven't seen a 4 valve industrial engine head. 4 valves generally flow more air than a 2 valve.
Probably not far away, Kawasaki FX series currently has 3 valves per cylinder , intended for commercial mowers. Can confirm, mad torque.

https://www.kawasakienginesusa.com/e...x/fx1000v.html
Reply With Quote
The Following 2 Users Say Thank You to karl For This Useful Post:
itsid (02-24-2020), Kartorbust (02-24-2020)
  #22  
Old 02-24-2020, 09:00 PM
Kartorbust's Avatar
Kartorbust Kartorbust is offline
Senior Member
 
Join Date: Feb 2016
Location: Lincoln, NE
Posts: 3,262
Thanks: 670
Thanked 844 Times in 713 Posts
Default

Quote:
Originally Posted by karl View Post
Probably not far away, Kawasaki FX series currently has 3 valves per cylinder , intended for commercial mowers. Can confirm, mad torque.

https://www.kawasakienginesusa.com/e...x/fx1000v.html
Attached Thumbnails
88WQFXx.jpg   takemymoney.jpg  

__________________
In the age of information, ignorance is a choice.
Reply With Quote
  #23  
Old 02-24-2020, 09:13 PM
itsid's Avatar
itsid itsid is offline
Moderator
 
Join Date: Jul 2013
Location: Ruhrpott [Germany]
Posts: 11,049
Thanks: 1,483
Thanked 4,593 Times in 3,467 Posts
Default

Quote:
Originally Posted by 65ShelbyClone View Post
Four stroke singles bite better on dirt, so that's at least one reason to use them.
true true.. 4strokes have more torque (dulled down statement )
but that's the thing, if you want low rpm torque,
then why do absolutely everything to reduce that in order to get higher rpms..
just to waste half of those to high engagment speed,
just so it moves at all?

We all know that if an engine has the same exact same horsepower at a certain rpm,
it also MUST have the exact same torque at that rpm.
And there's no handwaving around that.
And the engine that has MORE hp at that exact same rpms must also have more torque.

yes, two strokes bite way later (again washed out statement)
but if you raise your engagement speed to 4k+ anyways.. then the two stroke will likely be up to par out of the box.
plus it keeps on revving once the four strokes gave up.

So after all there's simply no sane reasoning to even try this past a certain point of money spent.

Don't get me wrong, having fun, throwing dirt does
NOT NEED sane reasoning whatsoever.. it's fun for a reason
I'm perfectly fine with that.

But it's terribly annoying to see -mostly- young guns spending
an unreasonable amount of money to get their lousy ootb
four strokes to rev higher and higher and higher,
just in order to waste most of those additional revolutions
to thermal losses
(clutch/belt wear.. stupid high engagement speeds in order to get the stupid setup to move at all and then gearing for 90mph when they only can achieve 55 anyways wasting another insane amount of rpms on the other end)
And then they get taught that this is how it has to be,
since racers do the exact same thing and in order to make it less terrible,
they 'need to' spend even more money.

When all that'd be needed really would be a better engine to start with.

that 10krpm 20 hp 190cc overhead cam four stroke for example
costs about 800 bucks new.
I'd bet it'd be hard to mod any industrial engine with the same amount of money and less than say 20hrs of labour (one busy wekend)
to get even close to that performance.

And if there's one k to spend, than an industrial plus mods
is not exactly the best engine to start with for many non racing folk,
yet they all get lured into that same madness since they think
"the racers should know what's best".

Again, I love the tilli block, and that head looks as georgeous as an engine part could.
I'd love to have one for myself (putting it on the shelf in the living room not having any real use for such )
but if I wanted some more serious than say 10hp of power
for some fun project..
throwing money at an industrial engine would be the exact last thing I'd think about.

Now.. don't let me bring you down ..
if that's the kind of fun and entertainment you're after that is perfectly legit of course (as if I had a vote LOOOL )

I'd just wanted to suggest,
that "more more more" might be easier and cheaper to find if
you think "other other other" too sometimes

'sid
__________________
Jokes about german sausage are the wurst.
Reply With Quote
The Following 2 Users Say Thank You to itsid For This Useful Post:
Flyinhillbilly (02-24-2020), Solomonster212 (02-25-2020)
  #24  
Old 02-24-2020, 10:20 PM
Flyinhillbilly's Avatar
Flyinhillbilly Flyinhillbilly is offline
The great cornholio
 
Join Date: Oct 2015
Location: North West Arkansas
Posts: 2,348
Thanks: 2,374
Thanked 1,088 Times in 770 Posts
Default

Quote:
Originally Posted by itsid View Post
true true.. 4strokes have more torque (dulled down statement )
but that's the thing, if you want low rpm torque,
then why do absolutely everything to reduce that in order to get higher rpms..
just to waste half of those to high engagment speed,
just so it moves at all?

We all know that if an engine has the same exact same horsepower at a certain rpm,
it also MUST have the exact same torque at that rpm.
And there's no handwaving around that.
And the engine that has MORE hp at that exact same rpms must also have more torque.

yes, two strokes bite way later (again washed out statement)
but if you raise your engagement speed to 4k+ anyways.. then the two stroke will likely be up to par out of the box.
plus it keeps on revving once the four strokes gave up.

So after all there's simply no sane reasoning to even try this past a certain point of money spent.

Don't get me wrong, having fun, throwing dirt does
NOT NEED sane reasoning whatsoever.. it's fun for a reason
I'm perfectly fine with that.

But it's terribly annoying to see -mostly- young guns spending
an unreasonable amount of money to get their lousy ootb
four strokes to rev higher and higher and higher,
just in order to waste most of those additional revolutions
to thermal losses
(clutch/belt wear.. stupid high engagement speeds in order to get the stupid setup to move at all and then gearing for 90mph when they only can achieve 55 anyways wasting another insane amount of rpms on the other end)
And then they get taught that this is how it has to be,
since racers do the exact same thing and in order to make it less terrible,
they 'need to' spend even more money.

When all that'd be needed really would be a better engine to start with.

that 10krpm 20 hp 190cc overhead cam four stroke for example
costs about 800 bucks new.
I'd bet it'd be hard to mod any industrial engine with the same amount of money and less than say 20hrs of labour (one busy wekend)
to get even close to that performance.

And if there's one k to spend, than an industrial plus mods
is not exactly the best engine to start with for many non racing folk,
yet they all get lured into that same madness since they think
"the racers should know what's best".

Again, I love the tilli block, and that head looks as georgeous as an engine part could.
I'd love to have one for myself (putting it on the shelf in the living room not having any real use for such )
but if I wanted some more serious than say 10hp of power
for some fun project..
throwing money at an industrial engine would be the exact last thing I'd think about.

Now.. don't let me bring you down ..
if that's the kind of fun and entertainment you're after that is perfectly legit of course (as if I had a vote LOOOL )

I'd just wanted to suggest,
that "more more more" might be easier and cheaper to find if
you think "other other other" too sometimes

'sid
I agree with all of this, what we do isn’t affordable, logical, or the most practical way of doing it, but it’s fun. I think we’re certainly on the same page there.
Something else about building these motors way up is diminishing returns. The farther you go, the less you gain. For instance, a cam, rod, flywheel, ported head with good springs, and a carb upgrade can take you past 15hp easily. Once you pass that point it starts to get expensive with lots of custom, and highly modified parts to get a few more HP. The difference between a stage 4 motor and a full on race motor is not that far apart in terms of horsepower, but miles and miles apart financially.
The more power you make, the more each HP costed.
__________________
You can't drink all day if you don't start in the morning
Reply With Quote
The Following 2 Users Say Thank You to Flyinhillbilly For This Useful Post:
itsid (02-25-2020), Solomonster212 (02-25-2020)
  #25  
Old 02-25-2020, 08:28 AM
Solomonster212's Avatar
Solomonster212 Solomonster212 is offline
High Compression Member
 
Join Date: Feb 2020
Location: Hoover, Alabama
Posts: 190
Thanks: 130
Thanked 31 Times in 28 Posts
Default

Quote:
Originally Posted by itsid View Post

We all know that if an engine has the same exact same horsepower at a certain rpm,
it also MUST have the exact same torque at that rpm.
And there's no handwaving around that.
And the engine that has MORE hp at that exact same rpms must also have more torque.
What? Maybe I missed something you wrote, but I highly disagree with this statement. Just because two engines will have the same power at a certain rpm DOES NOT mean that they will have the same torque at that rpm...

Whether we're talking cars or karts, or **** anything with an engine... Some modifications will sacrifice torque for gains of horsepower, and some will sacrifice horsepower for gains of torque. I've seen the numbers... It is entirely possible for one engine of the same make as the other to have 250whp @5500 and 225tq, while the other engine have 250whp also @5500 BUT have 200tq.


I'm not one for arguing by any means, rest assured. But I must know where you obtained that information, and why exactly you believe it?

---------- Post added at 09:28 AM ---------- Previous post was at 09:23 AM ----------

Quote:
Originally Posted by Flyinhillbilly View Post
Something else about building these motors way up is diminishing returns. The farther you go, the less you gain. For instance, a cam, rod, flywheel, ported head with good springs, and a carb upgrade can take you past 15hp easily. Once you pass that point it starts to get expensive with lots of custom, and highly modified parts to get a few more HP. The difference between a stage 4 motor and a full on race motor is not that far apart in terms of horsepower, but miles and miles apart financially.
The more power you make, the more each HP costed.
For sure. Regardless of the engine.
__________________
I do karting on the side... And cars on the other side... And --- wait, how many sides do I have?
Reply With Quote
  #26  
Old 02-25-2020, 09:58 AM
KartFab's Avatar
KartFab KartFab is offline
Senior Member
 
Join Date: Jan 2013
Location: Dallas, TX
Posts: 3,368
Thanks: 497
Thanked 1,494 Times in 1,054 Posts
Default

5252 RPM. Is the magic number. Just look at the basic formula to see 1 divided by 1 cancels out. 5252/5252=1, so at this exact RPM hp=tq.

This is the formula:
H = T x rpm/5252

This whole whp calculates losses through the trans, and is a measure of horsepower at the wheel, which is different than the HP an engine would make at the crank. If someone estimated losses differently, you could get a hp estimate that differs significantly from another. Basically, you can fudge the numbers easily, as the estimate of losses can be subjective.

You could have the same hp engine, but different items attached (water pump, alternator, fans, power steering, and transmission), and get a different WHP number, even though they make the same crank horsepower.

Additionally, inexperienced and experienced dyno operators can estimate losses and weather corrections in their favor, or fail to account for things that affect the number like engine inertia, tire pressure, and frictional losses within the dyno and wheel contact surface.

One example I saw recently was a dyno operator claiming he increased engine HP by about 10% by simply swapping out the flywheel. What he really did was fail to recalculate reduced engine inertia. The dyno software spat out a “higher number” because it was assuming the engine had a higher inertia than it actually did. Does an engine make more torque with a lighter flywheel? No. It has less inertia. Just one example of many I have seen while looking through data and talking to experts in the field.
__________________
Free Go Kart Plans https://kartfab.com Go Kart Videos https://www.youtube.com/c/KartFab
Reply With Quote
The Following User Says Thank You to KartFab For This Useful Post:
Solomonster212 (02-25-2020)
  #27  
Old 02-25-2020, 10:06 AM
Solomonster212's Avatar
Solomonster212 Solomonster212 is offline
High Compression Member
 
Join Date: Feb 2020
Location: Hoover, Alabama
Posts: 190
Thanks: 130
Thanked 31 Times in 28 Posts
Default

Quote:
Originally Posted by KartFab View Post
5252 RPM. Is the magic number. Just look at the basic formula to see 1 divided by 1 cancels out. 5252/5252=1, so at this exact RPM hp=tq.

This is the formula:
H = T x rpm/5252

This whole whp calculates losses through the trans, and is a measure of horsepower at the wheel, which is different than the HP an engine would make at the crank. If someone estimated losses differently, you could get a hp estimate that differs significantly from another. Basically, you can fudge the numbers easily, as the estimate of losses can be subjective.
Facts.

I'm used to the Mustang dyno, not very accustomed to the Dynajet... To us it only matters what it makes when mounted, anything else is irrelevant.
__________________
I do karting on the side... And cars on the other side... And --- wait, how many sides do I have?
Reply With Quote
  #28  
Old 02-25-2020, 05:44 PM
itsid's Avatar
itsid itsid is offline
Moderator
 
Join Date: Jul 2013
Location: Ruhrpott [Germany]
Posts: 11,049
Thanks: 1,483
Thanked 4,593 Times in 3,467 Posts
Default

Quote:
Originally Posted by Solomonster212 View Post
What? Maybe I missed something you wrote, but I highly disagree with this statement. Just because two engines will have the same power at a certain rpm DOES NOT mean that they will have the same torque at that rpm...
You cannot disagree with math I'm afraid or the fundamental rules of physics.
if you measure something different, it's for sure the measurement that's wrong I'm afraid

as we just discussed elsewhere just recently
Power (Watts) is defined as kgm²/s³
and Torque (Nm) is defined as kgm²/s²
and with that you already KNOW that torque per second is power
(kgm²/s² * 1/s = kgm²/s³)

Now we are dealing with rotational speed.. sooo we need to multiply with 2 Pi
1 round per second = 60 rounds per minute
3000 rpm = 50 rps...
And just like that..
12Nm * 50 rps * 2Pi = 3770 Watts

And if you fix two of those variables
(torque and rpm, or power and rpm, or power and torque)
the third MUST be the same as well, since there is no fourth variable that could have changed.
As simple as that.. no way to cheat..

And that's the exact equation where the "magic number" originates from too..
(since there is only ONE equation it can only be translated or rearranged but never be altered)

Nm * rpm/60 * 2 * Pi = Watt

A footpound of torque divided by 0.73756215 is almost exactly a Nm .
and a hp has 745.69987 Watts roughly

So in order to americanify that equation
we can replace Nm by (ftlbf / 0.73756215)
and Watts by (hp * 745.69987)
to make that equation look like that:

(ftlbf / 0.73756215) * (rpm/60) * 2 * Pi = hp * 745.69987
aint that terrible??

let's move some of the fixed values to the right, shall we?

ftlbf * rpm * 2 * Pi = hp * 745.69987 * 0.73756215 * 60
not better yet.. let's combine...

ftlbf * rpm * 2 * Pi = hp * 33000
oh how nice.. 33000 as if that was intentional..
yes, I used all decimal digits to get to 33000,
since that's what a hp was defined as originally:
as 33000 foot pounds of work per minute,
and the reason why the english hp is defined as 745.6998xxx Watts

but there are two pi left, you say.. and no 5252 to be seen so far...
well let's move the 2Pi over as well then

ftlbf * rpm = hp * 33000 / (2* Pi)
2Pi is about 6.28318531 right..

and 33000 divided by 6.28318531 is
5252.1131220

simplified to 5252 and moved back to the left you get
what Grant asked you to recall:
torque * rpm / 5252 = hp
This is what you should remember if you want to get an idea..
it's not precise, but surely precise enough for most occasions for sure

'sid
__________________
Jokes about german sausage are the wurst.
Reply With Quote
  #29  
Old 02-25-2020, 08:57 PM
Solomonster212's Avatar
Solomonster212 Solomonster212 is offline
High Compression Member
 
Join Date: Feb 2020
Location: Hoover, Alabama
Posts: 190
Thanks: 130
Thanked 31 Times in 28 Posts
Default

Thanks for the 4 subjects lessons all in one.

I will take note(s).
__________________
I do karting on the side... And cars on the other side... And --- wait, how many sides do I have?
Reply With Quote
  #30  
Old 02-26-2020, 08:04 PM
65ShelbyClone's Avatar
65ShelbyClone 65ShelbyClone is offline
Senior Member
 
Join Date: Jan 2018
Location: SoCal
Posts: 461
Thanks: 43
Thanked 181 Times in 151 Posts
Default

Spark ignition industrial engines often don't have more than two valves because they won't benefit from four and it's cheaper to make two. Lighter valves and big ports don't help an engine that spends life at 3600rpm.

Many diesel industrial engines have four valves though. The heads don't flow all that well because swirl and a fast, clean burn is more important.
__________________
I'll show those guys who's in top place, I'll really give 'em a hotrod race.
Reply With Quote
  #31  
Old 03-26-2020, 03:41 PM
Jhoppe Jhoppe is offline
Member
 
Join Date: Mar 2019
Location: Indiana (IN)
Posts: 92
Thanks: 13
Thanked 9 Times in 9 Posts
Default

Where are we at with this FHB? have you gotten your new head yet? How does it do?
Reply With Quote
  #32  
Old 03-27-2020, 08:21 AM
Flyinhillbilly's Avatar
Flyinhillbilly Flyinhillbilly is offline
The great cornholio
 
Join Date: Oct 2015
Location: North West Arkansas
Posts: 2,348
Thanks: 2,374
Thanked 1,088 Times in 770 Posts
Default

Quote:
Originally Posted by Jhoppe View Post
Where are we at with this FHB? have you gotten your new head yet? How does it do?
They’re not on the market yet, I got on the list way early. I did recently pick up a tillotson head that was built by one of the best in the business, and it straight rips and can be bought for $300. 32/28 stainless valves, with all the tricks. It flows 96.5 cfm. I took off a nice 32/28 head to put this one on, and there’s a clear difference between them. If you’re interested in one send me a pm and I’ll give you the guys contact info.
__________________
You can't drink all day if you don't start in the morning
Reply With Quote
  #33  
Old 03-30-2020, 12:18 AM
Jhoppe Jhoppe is offline
Member
 
Join Date: Mar 2019
Location: Indiana (IN)
Posts: 92
Thanks: 13
Thanked 9 Times in 9 Posts
Default

I appreciate the gesture, but I just have a yard Kart and I'm planning a minibike. I think that is a bit overkill for me! Thanks though!
Reply With Quote
Reply

Thread Tools
Display Modes

Posting Rules
You may not post new threads
You may not post replies
You may not post attachments
You may not edit your posts

BB code is On
Smilies are On
[IMG] code is On
HTML code is Off



All times are GMT -6. The time now is 03:59 PM.