Bore vs Stroke vs Displacement

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Old 09-21-2006, 06:35 PM
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When you start reading through the threads for the individuals engines, you start to get a real sense of what these numbers mean and what they don't mean. Just because th LL3 has the longest stroke, doesn't mean it delivers the best bottom-end performance throughout the lower powerband. Similarly, the shortest stroke doesn't mean that it doesn't deliver on the bottom-end. How very interesting.

Anybody have anything else to add to this or comment on?

Thanks!
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Old 09-21-2006, 06:44 PM
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Originally Posted by rmdhawaii
When you start reading through the threads for the individuals engines, you start to get a real sense of what these numbers mean and what they don't mean. Just because th LL3 has the longest stroke, doesn't mean it delivers the best bottom-end performance throughout the lower powerband. Similarly, the shortest stroke doesn't mean that it doesn't deliver on the bottom-end. How very interesting.

Anybody have anything else to add to this or comment on?

Thanks!
think you could find this info. for mugen x12 or jp x12
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Old 09-21-2006, 06:54 PM
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Code:
Engine               Bore  Stoke  Disp.
------              ----- ------  -----
Mugen X12S3          13.80  14.00  2.094
Found the info buried here: http://www.mugenracing.com/X12.htm
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Old 09-21-2006, 07:03 PM
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The other thing to consider in this is rod length, which has nothing to do with stroke. Shorter rod motors tend to have higher piston acceleration as well as having shorter TDC and BDC dwell times. This also affects the so called "low end" response.
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Old 09-21-2006, 07:15 PM
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Originally Posted by AMGRacer
The other thing to consider in this is rod length, which has nothing to do with stroke. Shorter rod motors tend to have higher piston acceleration as well as having shorter TDC and BDC dwell times. This also affects the so called "low end" response.
Unfortunately, manufacturers don't seem to publish the rod length!
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Old 09-21-2006, 07:19 PM
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Originally Posted by rmdhawaii
Unfortunately, manufacturers don't seem to publish the rod length!
Right, but I am sure that the RCTech readers of this topic could chime in with some responses here.

From what I remember the Picco motors had an ultra short rod, most novarossis a mid length rod and OSs (TRs and before) a long rod, along with the MT12 and CX 12 novarossis. My memory is pretty faulty though!
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Old 09-21-2006, 07:56 PM
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Originally Posted by rmdhawaii
When you start reading through the threads for the individuals engines, you start to get a real sense of what these numbers mean and what they don't mean. Just because th LL3 has the longest stroke, doesn't mean it delivers the best bottom-end performance throughout the lower powerband. Similarly, the shortest stroke doesn't mean that it doesn't deliver on the bottom-end. How very interesting.

Anybody have anything else to add to this or comment on?

Thanks!
I just wonder, with my LL3 i always knew it didn't make the most torque out of all engines but it felt really torquey. Is that just the powerband coming on or what? Personally i wasn't a fan of it working like that
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Old 09-21-2006, 08:03 PM
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Originally Posted by AMGRacer
Right, but I am sure that the RCTech readers of this topic could chime in with some responses here.

From what I remember the Picco motors had an ultra short rod, most novarossis a mid length rod and OSs (TRs and before) a long rod, along with the MT12 and CX 12 novarossis. My memory is pretty faulty though!
This list of engines was published by Dennis Richey long time ago on a post regarding pipe selection based on rod lenght. Of course thera are several new engines not posted, but it's a reference

Very short
HPI 15 FE
Rossi Pixi
Short
RB X12 and all the V12 derivatives
All Novarossi .12 engines and derivatives
STS D3, D3R
RD Logics RRE S3
OS TS & TZ
Mid length
Picco 12
Mega 12
Sirio 12 all
L.Collari 12 all
Long
STS MT12
Mugen MT12

AFM
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Old 09-21-2006, 08:07 PM
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Originally Posted by afm
This list of engines was published by Dennis Richey long time ago on a post regarding pipe selection based on rod lenght. Of course thera are several new engines not posted, but it's a reference

Very short
HPI 15 FE
Rossi Pixi
Short
RB X12 and all the V12 derivatives
All Novarossi .12 engines and derivatives
STS D3, D3R
RD Logics RRE S3
OS TS & TZ
Mid length
Picco 12
Mega 12
Sirio 12 all
L.Collari 12 all
Long
STS MT12
Mugen MT12

AFM
Great info thank AFM. Seems I was pretty much wrong on everything I said, I'm getting too old!
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Old 09-21-2006, 08:22 PM
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Cant be getting to old Al, seeing as how you just brought a MTX-4 for some more excitment!!!!
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Old 09-21-2006, 08:23 PM
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Originally Posted by hav_lova
I just wonder, with my LL3 i always knew it didn't make the most torque out of all engines but it felt really torquey. Is that just the powerband coming on or what? Personally i wasn't a fan of it working like that
If you haven't already, check out mtveten's posts in the Novarossi thread. That should explain some of what' you're experiencing.
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Old 09-21-2006, 08:28 PM
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Thanks AFM. That's a good starting point. Now I think I need to get some actual numbers and add it to the chart I started.
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Old 09-21-2006, 08:49 PM
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iv found the LL3 has a higher power band than the LS3 and to some this may fell like toque i think its more mid power but the LS3 has higher top speed. i think the megas are like this low and mid power. im getin old so idono. what i mean is the LS3 coms on later then the LL3 the sirios are like this to the power comes on later
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Old 09-21-2006, 09:09 PM
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Originally Posted by afm
Picco Micromotori makes Mega ZX engines, and also makes LRP engines. The specs of the three are quite similar, maybe a different timing spec on each brand, but the bore end stroke identical, thought this spec sheet for the LRP .12 Spec.2 Team engine might help you

Exhaust: rear exhaust
Displacement: .12 cu in (2.11cc)
Carb: 5.5mm slide carburetor
Crankshaft: SG shaft 12.0mm/7.0mm bore
Sleeve: ABC piston and sleeve
Ports: 3+1 ports. EFRA, DMC, OFMAV, SRCC, IFMAR, ROAR race legal.
Bore: 13.8mm
Stroke: 14.0mm
Piston: CNC machined high silicium alloy
Connecting Rod: New Fork shaped aluminum using special bushings
Rpm: 3,600-42,000rpm*
Hp: 1.11hp @ 34,500 rpm *
Torque: 32.46 Oz.In. @ 34,250 *
Weight: 221g

* Specifications on 30% Nitro fuel using Mugen - Shimo pipe and header at Nitrodyne Systems Dynamometer using corrected SAE factors.

AFM
hi afm.........

interesting.....max torque and peak power at almost the same rpm...........or am I wrong?
BTW: SAE want POWER in kW and TORQUE in N*m .....just kidding man!
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Old 09-21-2006, 11:54 PM
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Originally Posted by wallyedmonds
you dont know me to well do you LOL my 2 o.s motors the piston blowed up real good like, cuz the con rods wore out realy fast and i did not change them. ONE DAY OF RUNING.
Are you kidding? i'm not trying to be a smart ass or question your experience but, my dad and i both run TZ's and have not had one single problem. his, i think has done around 14+ litres and mine around 7-10 litres (its hard to know mine exactly, as we share fuel) and both engines perform like they did out of the box, both have incredible compression and i run mine hard, and its the original conrod in mine, although i believe my dads was replace after a couple litres. so i wonder, how the hell do you blow up an O.S. after
ONE DAY OF RUNING
?????

Come to think of it, he still uses both of my old os tr engines and i know for a fact one of them has run about 20 litres! the other around 8 and both go like an OS should!
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