| Author | Topic |
|---|
I supported Toymods
Location:
Perth
Registered:
May 2002
|
|
|
Location:
Adelaide
Registered:
June 2003
|
|
Re: Capacity vs Cylinders
|
Sun, 15 June 2003 10:29
 
|
 |
i think the revvyness of an engine has alot to do with the bore and stroke configuration of the engine,
i think square and oversquare engines tend to rev higher
|
|
|
I supported Toymods
Location:
Perth
Registered:
May 2002
|
|
Re: Capacity vs Cylinders
|
Sun, 15 June 2003 10:30
|
|
|
Yes, this I realise, but I'd like to just narrow down the characteristics of the engine through the capacity to cylinders ratio.
|
|
|
Location:
Brisbane
Registered:
June 2003
|
|
|
Location:
Sydney
Registered:
May 2002
|
|
Re: Capacity vs Cylinders
|
Sun, 15 June 2003 11:10
|
|
Hey mate.....thanx for asking the question for me
Bansheebuzz gave me this response...
"same capacity with more cylinders means
smaller, lighter pistons.
shorter stroke
more drag - due to more pistons and longer crank increased number of bearing etc.
This usually results in higher rpm limits and hp due to the lighter individual internals, smoother running and continual power strokes from each cylinder.
An engine with less cylinders tends to be more torqier but less hp "
|
|
|
Location:
Brisbane
Registered:
June 2003
|
|
|
Location:
Montrose, VIC
Registered:
May 2002
|
|
Re: Capacity vs Cylinders
|
Sun, 15 June 2003 11:29
|
|
|
That's about it - stroke length. The RB20 has a stroke of about 69.something, whereas the SR20 is 86x86 (same as 3S, 2JZ!). Guess which one is the nice revver! Likewise, RB26 and 1JZ, vs 2JZ and RB30 - big difference, and it's exactly as the stroke length suggests! That said, an inline six is also always nicer than an inline four - less nasty harmonics. Oh yeah, and the RB20 valvetrain takes the revs much better than the SR20!
|
|
|
Location:
Gold Coast
Registered:
January 2003
|
|
Re: Capacity vs Cylinders
|
Sun, 15 June 2003 11:35
|
|
| V8_MA61 wrote on Sun, 15 June 2003 21:26 |
"An engine with less cylinders tends to be more torqier but less hp "
thats a very general statement. Look at the main large engine orientated manufacturers - holden/chev/ford ...take their v8's..its the opposite of the spectrum...theres big capacity and large # of cylinders and they have big hp and loads of torque...when referring to torque vs size ratio i think the golden rule only applies to the same amount of cylinder engines. its more the capacity vs cylinders ratio rule when you can make statements like the above.
But lets not argue about v8s please.
|
i am aware if this but the original question was regarding same capacity with different number of cylinders. Which makes my statement true
ie 6cly 2litre vs 4cly 2litre
of coarse a larger capacity engine should produce more hp and torque. As they say you can't beat cubic inches
|
|
|
Location:
Brisbane
Registered:
June 2003
|
|
Re: Capacity vs Cylinders
|
Sun, 15 June 2003 11:43
|
|
apologies...just got that impression from what mani said above...wasnt told the full story 
|
|
|
Location:
Montrose, VIC
Registered:
May 2002
|
|
Re: Capacity vs Cylinders
|
Sun, 15 June 2003 11:45
|
|
|
Obviously, for a given capacity, more cylinders means smaller bore and, most importantly, stroke. Falcon six vs 1uz? RB26 vs Rodeo 2.6?? And lets not mention F1 engines, 3 litre V10 with 2.5ish bore/stroke ratio!
|
|
|
I supported Toymods
Location:
Perth
Registered:
May 2002
|
|
Re: Capacity vs Cylinders
|
Sun, 15 June 2003 11:48
|
|
Mani,
No problem dude, I was curious too 
Ok, so basically it comes down to the engine having a shorter stroke in most cases as the number of cylinders increases. The shorter stroke promotes less low-down torque, but allows the engine to thrive on revs.
Does this seem right? The other thing I'm getting from this, is that perhaps some of the extra power lost by the extra capacity is made up by the fact that the engine will rev harder to make the power? ie. 1UZFE vs 308 Holden etc.
|
|
|
Location:
Brisbane
Registered:
June 2003
|
|
Re: Capacity vs Cylinders
|
Sun, 15 June 2003 11:52
|
|
|
thats right man Key is The 1uz has a lot more detail under those those tappets than the 308 tho
|
|
|
I supported Toymods
Location:
Perth
Registered:
May 2002
|
|
Re: Capacity vs Cylinders
|
Sun, 15 June 2003 11:54
|
|
|
And most other generic V8's, but I think we've all been there one too many times
|
|
|
Location:
Brisbane
Registered:
June 2003
|
|
Re: Capacity vs Cylinders
|
Sun, 15 June 2003 11:55
|
|
|
yes! stop now please!
|
|
|
Location:
Darwin
Registered:
April 2003
|
|
Re: Capacity vs Cylinders
|
Tue, 17 June 2003 23:14
|
|
I would have thought that having six cylinders compared to four for a given size would make it smoother as you have two extra pistons firing.
Is that a valid comment?
|
|
|
Location:
Cabramatta, NSW
Registered:
May 2002
|
 Re: Capacity vs Cylinders
|
Wed, 18 June 2003 04:07
|
|
|
Thing is, give a 2.0L six and a 2.0L four, there's nothing stopping the six from having the same stroke as the four.
|
|
|
Club President
I supported Toymods
Location:
Sydney
Registered:
May 2002
|
 Re: Capacity vs Cylinders
|
Wed, 18 June 2003 04:33
|
|
mmm Ok you have my interest now
Just to throw in a few Toyota examples for the discussion.
3SGE verses 1G-GE ?? Both 2 liter's ones a 6 ones a 4 ! Both are Multivalve overhead cam twin cams. PLz comment.
( i don't know there stroke ? )
(lets not compare pushrods and mulitivalves and stuff keep em on a level playing feild. )
|
|
|
I supported Toymods
Location:
I renounced punctuation
Registered:
May 2002
|
|
|
I supported Toymods
Location:
Perth
Registered:
May 2002
|
|
Re: Capacity vs Cylinders
|
Wed, 18 June 2003 04:37
|
|
|
This would be generalising, but wouldn't the bottom-end of the 1G be more eager to rev given the shorter stroke (lets disregard valve setup)?
|
|
|
Location:
New Zealand
Registered:
May 2002
|
|
Re: Capacity vs Cylinders
|
Wed, 18 June 2003 05:09
|
|
I think it is quite a tricky area to compare motors like this. Usually if a manufacturer is designing a small capacity engine with multiple cylinders (e.g. 6 vs 4) they are looking for a revy motor so will give it short stroke rather than a smaller bore.
You really need to look at it on a cylinder by cylinder basis. What is the ratio between bore and stroke. Compare a 302 Chev to a 350. the shorter stroke (3in to 3.48?in stroke) allows the engine to rev higher but make less torque. Same goes for 3k versus 4k, 3k is much revier.
Best way to compare is to look at same capacity engines with different bore/stroke ratios and see how they compare with the same number of pistons.
The 3S-GE / 1G-GE is an interesting comparison but will be distorted by what the manufacturer wanted from the engine.
Hp is also only a measure of torque vs revs so is probably best to talk about where in the rev range the torque is made. The same (or even a little less) torque made 2000 rpm higher will give you a higher hp reading.
Just my ramblings.
Callum
|
|
|
I supported Toymods
Location:
Perth
Registered:
May 2002
|
|
Re: Capacity vs Cylinders
|
Wed, 18 June 2003 05:16
|
|
I think the goals for the 1G was that it had to be an inline six, and it had to fall into the 2l bracket for Japans weird road tax laws.
Aside from that, I reckon the 3SGE and 1GGE is a great comparison, the power generated by them was very similar. Near the end of its lifespan in 1992 (?) the 1GGE made 160hp. This was a pretty good comparison between that of the 3SGE which made between 156hp and 175hp depending on spec, around the same time too.
|
|
|
Location:
Kita-Ku, Sapporo, Japan
Registered:
January 2003
|
|
Re: Capacity vs Cylinders
|
Wed, 18 June 2003 05:38
|
|
| fingers wrote on Wed, 18 June 2003 09:14 |
I would have thought that having six cylinders compared to four for a given size would make it smoother as you have two extra pistons firing.
Is that a valid comment?
|
definitely, and is what everyone is forgetting.
the power output of a motor is not constant, but is a pulsing curve with one pulse for each piston firing.
take an extreme example.
a 3L 4 cyl, compared to a 3L V10
the 4cyl will have two power pulses per revolution, and the V10 will have 5 pulses. so the V10 will have much smoother power delivery, and i think that the average torque (area under the curve of torque vs time) will be higher for the V10.
an analogy is single phase vs 3 phase electricity. liek comparing single cylinder vs 3 cylinder. (unfortunately it's like comparing different size engines tho)
if you look at a graph of the three suprimposed voltage curves for 3 phase, the average voltage is higher.. 415V vs 240V, and you have 3 times the amperage available...
i'm sure an elec engineer will be able to do the math as i'm a bit rusty, but i think that for a 3 phase circuit with same amperage going thru it, it will have higher power than a single phase with same amperage.
yes the mechanical losses will be higher, but not by much..
a direct example from the bike world for 1L motors(assuming similar development) a YZF-R1 (4cyl) has about 105Nm, where a VTR-SP1 has about 100Nm, so 5% less for same capacity. they have vry diferent torque curves too, with the R1 having torque higher in the rev range, and the SP1 having a wider and flatter, but lower rpm, torque curve.....
Cya, Stewart
|
|
|
Location:
Perth
Registered:
January 2003
|
|
Re: Capacity vs Cylinders
|
Wed, 18 June 2003 05:51
|
|
|
Having more cylinders decreases the distance the flame front has to travel to combust all of the contents of the cylinder. This is beneficial for high rev operation, because less time is taken to develop pressure after firing. It also reduces the likelyhood of detonation.
|
|
|
Capacity vs Cylinders
