Author Topic: Question about removing pistons to change displacement  (Read 5043 times)

0 Members and 1 Guest are viewing this topic.

Offline RZ350

  • Full Member
  • ***
  • Posts: 66
Question about removing pistons to change displacement
« on: August 19, 2009, 08:56:55 PM »
Let's say I have a 636cc Kawasaki engine that I want to run in the 350cc class, removing two pistons will give 318cc's, that I know...

If I were to machine the top of the piston off,  remove the rings, add weight to the pin maybe to keep the balance correct, would this be legal, or would it still be counted as an active cylinder?

No induction or exhaust on the dead cylinders either, and the valvetrain either removed or disabled...

I understand that I could make a bob weight and just put it on the rod journal, but how would that affect the balance without having a reciprocating component to the balance?
238 MPH at Bonneville

Offline 4-barrel Mike

  • Hero Member
  • *****
  • Posts: 3173
  • Any fool can drive a V8
Re: Question about removing pistons to change displacement
« Reply #1 on: August 19, 2009, 09:35:31 PM »
Dunno nuttin' 'bout bikes, but here is a thread about cars doing that: http://www.landracing.com/forum/index.php/topic,4368.msg58248.html#msg58248

Mike
Mike Kelly - PROUD owner of the V4F that powered the #1931 VGC to a 82.803 mph record in 2008!

Offline sabat

  • Hero Member
  • *****
  • Posts: 1539
Re: Question about removing pistons to change displacement
« Reply #2 on: August 19, 2009, 09:42:34 PM »
Sounds legal to me Troy, but I don't know. How much power can you make with a massaged RZ350?

Offline 1212FBGS

  • Hero Member
  • *****
  • Posts: 2532
    • http://www.motobody.com
Re: Question about removing pistons to change displacement
« Reply #3 on: August 19, 2009, 11:25:27 PM »
i've been in that grey area before.....best bet would be to remove the the pistons, rods, and cut the cams..... have it inspected and sealed before the pass...... then run the RZ350!
kent

Offline panic

  • Sr. Member
  • ****
  • Posts: 845
    • My tech papers
Re: Question about removing pistons to change displacement
« Reply #4 on: August 20, 2009, 12:36:18 PM »
Based on plain language, physics, and how the engine works you're legal because the "displacement" has been reduced.
What non-functioning parts might do if they were restored is as pointless a subject of conjecture as "what if he swapped engines?".
A pass/fail that begins with the presumption of bad intent and fraud by the submitter tells me that there's something wrong with the process. Do a search for some scary examples of the rule-maker's mind-set.
If they insist that only certain methods can be used to do this, and they're not specified, you're going to lose - being right and being legal are widely separated.

Offline RichFox

  • Hero Member
  • *****
  • Posts: 2663
Re: Question about removing pistons to change displacement
« Reply #5 on: August 20, 2009, 02:52:41 PM »
180 cid Chevys have run before with all the pistons in and just the pushrods removed and plugs in the lifter bores. Made a V4 SBC. If you burned a piston you could just move the lifters and pushrods around. Don't know if any records got set.

Offline Ron Gibson

  • Sr. Member
  • ****
  • Posts: 770
Re: Question about removing pistons to change displacement
« Reply #6 on: August 20, 2009, 07:31:10 PM »
Didn't Freddy Larson set a record in the liner with a 180 ci sbc as you describe? A mind is a terrible thing to waste, but mine is already gone so my memory be wrong.
IIRC, years ago he told a bunch of us over adult beverages at the motel that he wondered about it, pulled 4 spark plug wires off his El Camino, drove around the block then built one for the liner.

Ron
Life is an abrasive. Whether you get ground away or polished to a shine depends on what you are made of.

Offline desotoman

  • Hero Member
  • *****
  • Posts: 2816
Re: Question about removing pistons to change displacement
« Reply #7 on: August 20, 2009, 07:57:37 PM »
I thought the 3 liter motor was a V-8 run as a V-8, but the 2.0 liter motor was a 4 cyl. V-8. At least that is what I remember.

Tom G.
I love the USA. How much longer will we be a free nation?

Asking questions is one's only way of getting answers.

The rational person lets verified facts form or modify his opinion.  The ideologue ignores verified facts which don't fit his preconceived opinions.

Offline RichFox

  • Hero Member
  • *****
  • Posts: 2663
Re: Question about removing pistons to change displacement
« Reply #8 on: August 20, 2009, 09:34:57 PM »
I was thinking of Solomen and Hardsock

Offline Freud

  • Hero Member
  • *****
  • Posts: 5419
Re: Question about removing pistons to change displacement
« Reply #9 on: August 20, 2009, 11:22:32 PM »
I too was   "I was thinking of Solomen and Hardsock"

In 1968 ( or something like that) Treit and I were on our way. (If I have to tell u where we were going, u don't belong on this site.) We

 passed a VW Square back between somewhere and Pendleton, Oregon. It had a COMPLETE flathead in the back end.

In the window was written....the prayer of the B'ville racer.  "PRAY FOR GOOD SALT."

Treits sedan delivery had a 428 Ford in it, a great 4 MPG rig, and we f'ing smoked him, but on the way by we rolled

down the electric window and asked...."ya goin' to Bonneville?" A no sound answer from his moving mouth was, "I'll see u there?"

He disappeared in the rear view mirror.  We stopped in Pendleton for some nondescript  reason, and he found us. Short

conversation, "ya goin' to Bonneville?" Reply, "yep."  His to the point answer, "I'll see u there." That was about 40 years

ago and except for the years that they didn't have a car because it burned in the huge Oakland fire, we have seen them

ever since. We see them annually, or anally at Motel 6.

They still haven't gone 300 with their roadster but Stan Back tells me no one else has either.

We still pray for good salt and they still pray that something doesn't break on the 554 roadster.

They sure have a good tow rig now. That shows they have progressed with the help of some American Manufacturer.

For all I know they may still be using the single axle trailer that they snatched from  Reggie Jackson's back yard after the fire.

My short term memory is failing but I still remember them when they didn't have to shave. Treit remembers we were in 3rd gear

when we passed him.

Recall is failing but I remember the humiliating experiences we have subjected some of our friends to.

Footnote: We didn't stay at the 6 that year. It was at least 20 year more before it was built.


FREUD
« Last Edit: August 20, 2009, 11:24:30 PM by Freud »
Since '63

Offline 4-barrel Mike

  • Hero Member
  • *****
  • Posts: 3173
  • Any fool can drive a V8
Re: Question about removing pistons to change displacement
« Reply #10 on: August 21, 2009, 12:40:39 AM »
Was that the sedan delivery with the beer tap in the dash?

Mike
Mike Kelly - PROUD owner of the V4F that powered the #1931 VGC to a 82.803 mph record in 2008!

Offline sockjohn

  • Sr. Member
  • ****
  • Posts: 364
Re: Question about removing pistons to change displacement
« Reply #11 on: August 21, 2009, 09:44:50 AM »
If I were you I would send an email to the tech person just to be sure.

My first thought is that considering how finely balanced the manufacturers make their engines, any thing that counters that is a risk.  Maybe it's an imaginary risk, but something to consider.

The easy way to keep the engine balanced is to leave the pistons and everything else alone (except maybe top ring) and remove the valve train components.  The question is would that be sufficient for tech?  I don't know.

My second thought is if you spent the time money and effort to destroke the motor (left as a 4 cyl) that motor would breath really, really well.

FWIW, a 250 two stroke and a big bore kit would get you into the low end of the 350cc class.  Not the most reliable way to get power, but plenty have done it before and it's off the shelf.  They aren't that bad to kick...

Offline sockjohn

  • Sr. Member
  • ****
  • Posts: 364
Re: Question about removing pistons to change displacement
« Reply #12 on: August 21, 2009, 09:48:13 AM »
They still haven't gone 300 with their roadster but Stan Back tells me no one else has either.

We still pray for good salt and they still pray that something doesn't break on the 554 roadster.

People say it's the journey not the destination, and I imagine the records that take decades to achieve are all the more sweet in the taking, but hope I get mine sooner than that! 

 :cheers:

Offline Jonny Hotnuts

  • Hero Member
  • *****
  • Posts: 1522
Re: Question about removing pistons to change displacement
« Reply #13 on: August 21, 2009, 12:02:45 PM »
I think it would be neat to have engines that snapped together like legos. A "master" engine connected to the drive that could allow an identical engine be bolted to its front and connect to the crank making the engine double in displacement.
jonny_hotnuts@hotmail.com

"Sometimes it is impossible to deal with her, but most of the time she is very sweet, and if you caress her properly she will sing beautifully."
*Andres Segovia
(when Im not working on the car, I am ususally playing classical guitar)

Offline John Burk

  • Sr. Member
  • ****
  • Posts: 695
Re: Question about removing pistons to change displacement
« Reply #14 on: August 21, 2009, 12:44:35 PM »
In maybe 2002 Fred Dannenfelzer's lakester engine looked normal but with E/BFL on the body . They had a 180 deg crank and 4 pistons and the second head to cover the blank holes .