Hi there,

Just wondering what makes the the 3.0L go to be 3.5L in the 6g74 range.

Is it that the 'bore' it out or something.?

I dunno that why I'm asking.

Rob.

Completely different block iirc, it does sit a bit higher then the 6g72.

Completely different block iirc, it does sit a bit higher then the 6g72.

Wrong again

Same block slightly larger bore, piston heads different and different deck height (18mm)

Wrong again

Same block slightly larger bore, piston heads different and different deck height (18mm)
Wrong again. A different deck height would mean a different block. You just dont "bolt" 18mm of deck height onto a 6G72.

Oh and the 3.5's have a different crank to a 3.0.

Wrong again. A different deck height would mean a different block. You just dont "bolt" 18mm of deck height onto a 6G72.

:bowrofl: Thanks.

:bowrofl: Thanks.
Believe me when i say it was my pleasure! lol

Wrong again

Same block slightly larger bore, piston heads different and different deck height (18mm)

Block is different around the crank support webbing. 3.5L has 4bolt mains where as 3.0L has 2 bolt mains, 3.0L crank has 50mm big end journals 3.5L crank has 55mm big end journals

Block is different around the crank support webbing. 3.5L has 4bolt mains where as 3.0L has 2 bolt mains, 3.0L crank has 50mm big end journals 3.5L crank has 55mm big end journals
Excellent. I have learnt something new! I love it when someone who actually knows his stuff posts an answer.

Excellent. I have learnt something new! I love it when someone who actually knows his stuff posts an answer.
I know it secretly turns you on :P;)

Block is different around the crank support webbing. 3.5L has 4bolt mains where as 3.0L has 2 bolt mains, 3.0L crank has 50mm big end journals 3.5L crank has 55mm big end journals

you shiraz'ing amazing.

ok but the .5L comes out with the boring right??

different bore and longer throw

Block is different around the crank support webbing. 3.5L has 4bolt mains where as 3.0L has 2 bolt mains, 3.0L crank has 50mm big end journals 3.5L crank has 55mm big end journals

This is why when ARP rod bolts (ARP part number 107-6004) are used, the rod caps on the 3.5L have to be spotfaced abit more so as to allow a couple of extra threads through so to acheive at least 2 threads of stickout when the nuts are torqued to spec.

Sorry if that is a bit over peoples heads lol

ok but the .5L comes out with the boring right??


And a slightly longer stroke Rob. IIRC, the extra cc's from the 3.0 to the 3.5 only came from increase bore and stroke. Maybe Jason can confrim this for me?

What are you looking at doing?

ok but the .5L comes out with the boring right??

1.9mm bigger bore and 9.8mm longer stroke on the 3.5L

that is one advantage the 72 had over the 74, shorter throw meant it was a bit keener to rev harder.

This is why when ARP rod bolts (ARP part number 107-6004) are used, the rod caps on the 3.5L have to be spotfaced abit more so as to allow a couple of extra threads through so to acheive at least 2 threads of stickout when the nuts are torqued to spec.

Sorry if that is a bit over peoples heads lol




1.9mm bigger bore and 9.8mm longer stroke on the 3.5L


Is this all quoted off the top of your head? Can anyone tap this bloke for his knowledge, and put it in a book...

that is one advantage the 72 had over the 74, shorter throw meant it was a bit keener to rev harder.

Yes but it also means the 3.0L has less torque especially low down in the rev range.

When you say stroke do you mean the length that the piston travels and bore as in bigger piston?? and whats IIRC?

theres a cheap one around where i am and im thinkin i might grab it just to have a play with it ... im just interested in what would be the differences between them and what they did to make it a bigger engine...

The Book of AMC :cool:

Should go in the Wiki

that is one advantage the 72 had over the 74, shorter throw meant it was a bit keener to rev harder.
It'd be like a few hundred rev's if that, hardly anything you'd miss in favor of all the extra torque. If you like high revving motors stick a honda Vtec in then :P

When you say stroke do you mean the length that the piston travels and bore as in bigger piston?? and whats IIRC?

theres a cheap one around where i am and im thinkin i might grab it just to have a play with it ... im just interested in what would be the differences between them and what they did to make it a bigger engine...

Correct on both counts rob, although bore specifically relates to the dimension available in the cylinder when the piston is at point 1 of the stroke.

When you say stroke do you mean the length that the piston travels and bore as in bigger piston?? and whats IIRC?

theres a cheap one around where i am and im thinkin i might grab it just to have a play with it ... im just interested in what would be the differences between them and what they did to make it a bigger engine...
Yes, yes, and "If I Remember Correctly"

']It'd be like a few hundred rev's if that, hardly anything you'd miss in favor of all the extra torque. If you like high revving motors stick a honda Vtec in then :P


LOL im a massive fan of torque paul, quite handy in a large-ish 1500kg sedan. Certainly not knocking the 74 in any way.

LOL im a massive fan of torque paul, quite handy in a large-ish 1500kg sedan. Certainly not knocking the 74 in any way.

Ya can certainly make the 3.5L rev like hell with abit of engine work :badgrin:

hopefully one day I can do something with mine to make it go a bit harder

Ya can certainly make the 3.5L rev like hell with abit of engine work :badgrin:
Would you like to explain how ??? haha

ok so basically alot of things go on when making it go up .5L.... but overall it seems to be a completly different engine all together...

Would you like to explain how ??? haha

ok so basically alot of things go on when making it go up .5L.... but overall it seems to be a completly different engine all together...

The 3.5L aint completely different, it does share the same heads as the 3.0L but the bottom end is nearly all different.

']It'd be like a few hundred rev's if that, hardly anything you'd miss in favor of all the extra torque. If you like high revving motors stick a honda Vtec in then :P


The 72 and 74 have the same redline Paul. Because the 72 has a lower rotating mass, it revs quicker than the 3.5. Your'e rright tho, ive had a manual 72 and 74, and the 74 pulls harder, but fork me the 72 loved to rev.

So how is the 380 engine different again? More bore or stroke, or both?

Don't know how well a 3.5L or 380 motor revs out - it doesn't need to, but the 3.0L sure needs to, gutless below 3,000 rpm. The 3.0L would be so much better as a manual, where you have control over the revs.

380 engine is 2mm bigger bore and 4.2mm longer stroke

So how is the 380 engine different again? More bore or stroke, or both?

Don't know how well a 3.5L or 380 motor revs out - it doesn't need to, but the 3.0L sure needs to, gutless below 3,000 rpm. The 3.0L would be so much better as a manual, where you have control over the revs.
I'm prob going to get smashed here.... but i think that the 380 engine is exactly the same as the Ralliart engine except this 'boring' thing ... which take it to .8L

So how is the 380 engine different again? More bore or stroke, or both?

Don't know how well a 3.5L or 380 motor revs out - it doesn't need to, but the 3.0L sure needs to, gutless below 3,000 rpm. The 3.0L would be so much better as a manual, where you have control over the revs.

3.8L has a 2mm bigger bore and 4.2mm longer stroke than the 3.5L

I'm prob going to get smashed here.... but i think that the 380 engine is exactly the same as the Ralliart engine except this 'boring' thing ... which take it to .8L

No they have similarities (cam and valve spring specs) but they are not exactly the same engine

Actual numbers anyone?

3.0L Bore = 91.1 mm
Stroke = 76.0 mm

Explains why it needs to rev. A 3 inch stroke? My BEEP moves more than that!

Actual numbers anyone?

3.0L Bore = 91.1 mm
Stroke = 76.0 mm

Explains why it needs to rev. A 3 inch stroke? My BEEP moves more than that!

3.0L Bore = 91.1mm, Stroke = 76mm

3.5L Bore = 93mm, Stroke = 85.8mm

3.8L Bore = 95mm, Stroke = 90mm

Great! Ta muchly!

3 inch stroke isn't that bad. Comparable to most small-ish capacity V6's...

All the 3 engines above are whats called a oversquare design which means the bore is bigger than the stroke, this normally means a fairly revvy engine.

A undersquare design is one with a smaller bore than the stroke this normally means a less revvy engine BUT torquier down low. Example ford falcon 4L has a 92mm bore and a 99mm stroke, Ford 5.4L V8 has a 90.2mm Bore and a 105.8mm stroke

cool :)

Honda did a lot of research in the stroke:bore ratio and how it affects engine performance, way back in the 60s and 70s. Pretty much decided if you wanted performance, you went short stroke and wide bore, with lots of valves, max bhp at high revs but poor torque down low - some of their early race bike motors revved like banshees but were hard to ride because of the narrow power band. They even experimented with oval shaped pistons in order to have lots of valves per cylinder! Never made it into production though. :rant:

Useless fact coming up:

If you have a V6 with bore and stroke of 100 mm its capacity would be 4.7L

They even experimented with oval shaped pistons in order to have lots of valves per cylinder! Never made it into production though. :rant:

Yeah it did. Honda NR500. From memoey it was the most expensive production bike ever made. It was a v4, but had 8 crank shafts and 32 valves. Reason they did this was there was a 4 cyl limit on motogp bike and they wanted to see if they could make a v8 with only 4 cyl(basically)

Sorry, my bad, the NR500 was the race bike, production bike was the NR750.

http://world.honda.com/history/challenge/1979pistonengine/img/pho_04.jpg
http://world.honda.com/history/challenge/1979pistonengine/img/pho_02.jpg

that is mad! Did it go alright?

OH MY GAWD! They actually made it? OMG OMG

LOL The twin conrods make the piston look like siamese twins!!

OH MY GAWD! They actually made it? OMG OMG


Yeah, they made it. The idea was to have a v8 with only 4 pistons if you get what i mean.
Also, it had 8 con rods, not eight crank shafts....

Here is the production model.
Honda NR750 (http://www.v-four.freeserve.co.uk/nr750.htm)

http://www.v-four.freeserve.co.uk/images/nr750.jpg

Courtesy of wikipedia

http://upload.wikimedia.org/wikipedia/commons/1/18/Ovalpiston.jpg

What an ingenious idea...
Has any car ever come out with something similar?
that would of made some good power..

you could have a V16 in the same dimensions as a V8 :cool:

Good to see this thread has stayed on topic lol

Good to see this thread has stayed on topic lol


i was thinking the smae thing before. It was relevent to a post made though.

i was thinking the smae thing before. It was relevent to a post made though.

True, but the thread was about the V6 magna engine and then 1 post turns into a bloody honda bike engine thread lol

Yeah, life is like that at times. Made the thread much more interesting, don't ya think tho?

Yeah, life is like that at times. Made the thread much more interesting, don't ya think tho?

Maybe but probably not for the orginial person who started this thread. lol

Maybe but probably not for the orginial person who started this thread. lol
Concur....

If you pull an engine apart and clean it out real good and smooth it and stuff can you gain any extra power out of it?

Of course, its one of those "one percenter" jobs, that by itself isn't worth lots of power, but in combination with other "one percenters" adds up to a decent increase in power.

Some Power can be gained from a "port and polish" just like in Gran Turismo.

Some Power can be gained from a "port and polish" just like in Gran Turismo.

Not until you are pumping out decent hp. I think Jason flow tested a set of standard heads, good for 350hp right Jase?

Not until you are pumping out decent hp. I think Jason flow tested a set of standard heads, good for 350hp right Jase?

Stock ralliart heads (which have no port mods over standard heads) came up with a potential hp figure of just over 370hp, which is pretty good.

Its a shame MMAL didn't implement other mods to the Ralliart heads which they tested, but all we get is the deshrouding cause it didn't cost them. :doubt:

So can you bolt an 3.5ltr or a 3.8ltr engine in where a 3.0ltr engine came out of?

As with the honda design.
They honda have never shown any photo's (or drawings)of the rings
In November 1977 Honda announced it would be returning to motorcycle Grand Prix racing using four stroke technology. Even though two-stroke engines dominated motorcycle Grand Prix racing in the late 1970s, Honda felt bound by their convictions to race what they sold and thus decided to compete using a high-technology, four-stroke race bike. Since a conventional four-stroke, four-cylinder engine could not produce the same power of its two-stroke rivals, Honda had to increase the valve area in order to be competitive. The rules at the time allowed up to four combustion chambers so honda designed a 32 valve V8 with four pairs of linked combustion.
This then evolved into an innovative engine with four oval-shaped cylinders. The oval cylinders allowed room for 32 valves and eight spark plugs, the same as that of an eight-cylinder engine while staying within the four cylinder rules limit. chambers
A lightened, tuned NR, makes 150bhp @ 15,500rpm and weighinhg just 180kg .


sorry to bore you with crap
Thanks
Sumpoiler

Right..............