OK, OK, I just had to get the first ever post in a forum, kind of like walking in fresh snow.
It won't happen again, please don't whack me
OK, its a 414 SB stroker, ported W2's, forged CP pistons, H-beams, etc, does that qualify me!
I have an engine....
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I have an engine....
.....just like the rest of you
OK, OK, I just had to get the first ever post in a forum, kind of like walking in fresh snow.
It won't happen again, please don't whack me
OK, its a 414 SB stroker, ported W2's, forged CP pistons, H-beams, etc, does that qualify me!
OK, OK, I just had to get the first ever post in a forum, kind of like walking in fresh snow.
It won't happen again, please don't whack me
OK, its a 414 SB stroker, ported W2's, forged CP pistons, H-beams, etc, does that qualify me!
At this point I think I'm just glad to have got this working 
OK OK....something technical
Why go to a stroker??
Well, for a start you get displacement, which as we all know there is no replacement for.
At the same time as big-block cubes you get to keep the lighter weight of a smallblock, plus the distribution better for handling (yes, I will be going round corners!)
Also the longer stroke produces more torque, which again as we all know is what it's really about on the street. The idea of the engine is to have torque on demand at any time. No good having to wind it up before it delivers (that's fine on the strip of course).
Some people prefer shorter strokes because they rev higher and ultimately revs equal horsepower. But this will rev easily to 6K+, could probably buzz it to 7K, but why bother. RPM Ruins Peoples Motors, the higher you rev the proportionately more stress you put on the engine, and for a street motor I wanted lots of torque & power down low, not too worried about squeezing the last drop at 7500rpm.
Stroking a motor can also increase the side loads on your pistons, but the rod ratio on a 4" stroke SB is no worse than many production engines, so that's not an issue.
You want good breathing on a motor like this (although it would still make power with ported stock heads), so I went for W2's, Chryslers famous 'Pro Stock' head from the early 70's. Bang for the buck, you can't beat them. OK they're cast iron, so they weigh more than ally, but like-for-like a cast head will make more power than ally anyway (let's stir the pot) and these ones flow better than a ported Edelbrock head (actually a stock W2 would flow more than some ported EB's). They've been ported and flowed at 300 cfm, plenty for my needs. Probably overkill for a standard street SB, but a stroker will lap em up!
Lastly, with the increased stroke and displacement you can use a much larger cam and it will still idle nicely and behave itself. The same cam in a standard displacement SB would be much more peaky and idle rougher.
And if nothing else, it's a bit different! As far as I'm aware mine was the first SB stroker over here? It won't be the first to run (we know who you are...) but they ain't exactly thick on the ground and it's nice to travel a slightly different road. Wait until I EFI it!
Alright? there is some technical stuff in there......might have to reuse some of this in a prgress report.
Why go to a stroker??
Well, for a start you get displacement, which as we all know there is no replacement for.
At the same time as big-block cubes you get to keep the lighter weight of a smallblock, plus the distribution better for handling (yes, I will be going round corners!)
Also the longer stroke produces more torque, which again as we all know is what it's really about on the street. The idea of the engine is to have torque on demand at any time. No good having to wind it up before it delivers (that's fine on the strip of course).
Some people prefer shorter strokes because they rev higher and ultimately revs equal horsepower. But this will rev easily to 6K+, could probably buzz it to 7K, but why bother. RPM Ruins Peoples Motors, the higher you rev the proportionately more stress you put on the engine, and for a street motor I wanted lots of torque & power down low, not too worried about squeezing the last drop at 7500rpm.
Stroking a motor can also increase the side loads on your pistons, but the rod ratio on a 4" stroke SB is no worse than many production engines, so that's not an issue.
You want good breathing on a motor like this (although it would still make power with ported stock heads), so I went for W2's, Chryslers famous 'Pro Stock' head from the early 70's. Bang for the buck, you can't beat them. OK they're cast iron, so they weigh more than ally, but like-for-like a cast head will make more power than ally anyway (let's stir the pot) and these ones flow better than a ported Edelbrock head (actually a stock W2 would flow more than some ported EB's). They've been ported and flowed at 300 cfm, plenty for my needs. Probably overkill for a standard street SB, but a stroker will lap em up!
Lastly, with the increased stroke and displacement you can use a much larger cam and it will still idle nicely and behave itself. The same cam in a standard displacement SB would be much more peaky and idle rougher.
And if nothing else, it's a bit different! As far as I'm aware mine was the first SB stroker over here? It won't be the first to run
(we know who you are...) but they ain't exactly thick on the ground and it's nice to travel a slightly different road. Wait until I EFI it!Alright? there is some technical stuff in there......might have to reuse some of this in a prgress report.
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Dave-R
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Sounds like a great engine. A mate of mine needs a crank for a 360 so I have talked him into going the 4-inch stroke route for 408 inches.
The only drawback to a long stroke is piston speed. The longer the stroke the faster the piston has to go to get from top to bottom (and back again!
) in any given time. A high piston speed is generally considered a bad thing because of wear and friction losses which limit power due to torque falling off faster at high rpms.
However these are all things we don't need to worry about at our performance levels.
Also bear in mind that a longer stroke with any given cam will actually reduce peak HP because peak torque only goes up slightly but moves down the rpm range a lot.
But this can have advantages as you say because with a hotter cam although peak horsepower may be down a touch with a longer stroke it will bring the power into a more usable rpm range where you can actually use it.
All in all I like stroker small blocks and 'B' engines.
The only drawback to a long stroke is piston speed. The longer the stroke the faster the piston has to go to get from top to bottom (and back again!
) in any given time. A high piston speed is generally considered a bad thing because of wear and friction losses which limit power due to torque falling off faster at high rpms.However these are all things we don't need to worry about at our performance levels.
Also bear in mind that a longer stroke with any given cam will actually reduce peak HP because peak torque only goes up slightly but moves down the rpm range a lot.
But this can have advantages as you say because with a hotter cam although peak horsepower may be down a touch with a longer stroke it will bring the power into a more usable rpm range where you can actually use it.
All in all I like stroker small blocks and 'B' engines.
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Anonymous
I would have thought that unless you are going for high rpm power launches, a stroker would be perfect?
Having a wide torque curve is excellent for street driving and makes towing etc easier too. Can anyone give me numbers for the mean and max piston speed on a stoker? The moment of inertia of the bottom end (per piston and and compound dynamics) should be an interesteing figure too. :happy11:
Having a wide torque curve is excellent for street driving and makes towing etc easier too. Can anyone give me numbers for the mean and max piston speed on a stoker? The moment of inertia of the bottom end (per piston and and compound dynamics) should be an interesteing figure too. :happy11:
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Dave-R
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Work it out yourself college boy! 
The average speed is easy.
4-inch stroke (as an example) is the distance in one direction so it goes 8 inches in one revolution so speed = 8 x rpm.
So at 6000rpm you are talking 4000 feet per min (average in the bore) It must be faster than that in the middle of a stroke and slower at the ends of course.
I just did a quick edit because I multiplied by 60 once too much!
I should have left the sums to you James. 
The average speed is easy.
4-inch stroke (as an example) is the distance in one direction so it goes 8 inches in one revolution so speed = 8 x rpm.
So at 6000rpm you are talking 4000 feet per min (average in the bore) It must be faster than that in the middle of a stroke and slower at the ends of course.
I just did a quick edit because I multiplied by 60 once too much!
I should have left the sums to you James. 
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Dave-R
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Mechanical losses are made up of stuff like piston ring friction. A long stroke adds to that.
Other factors are bearings and seal friction, valvetrain and spring pressure, accessory drag, pumping losses (dragging the air in and compressing it) etc. The losses induced by these things increase with engine speed. But they increase with the square of engine speed. That is to say that you double engine speed and you quadruple the mechanical losses.
Also included in these losses is the inertia of the moving parts. Any part that has to change direction robs power. Things like the pistons/rods, even the lifters, rockers and valves. The heavier the part or the faster it has to change direction the more power it robs. Again ? these losses go up as the square of engine speed. 4 x the engine speed and you get 16 x the losses.
But as i said we don't have to worry about these minor details at our level.
Other factors are bearings and seal friction, valvetrain and spring pressure, accessory drag, pumping losses (dragging the air in and compressing it) etc. The losses induced by these things increase with engine speed. But they increase with the square of engine speed. That is to say that you double engine speed and you quadruple the mechanical losses.
Also included in these losses is the inertia of the moving parts. Any part that has to change direction robs power. Things like the pistons/rods, even the lifters, rockers and valves. The heavier the part or the faster it has to change direction the more power it robs. Again ? these losses go up as the square of engine speed. 4 x the engine speed and you get 16 x the losses.
But as i said we don't have to worry about these minor details at our level.
Yep, pretty much agree with all the comments.
A broad torque curve is exactly what I want on the street. Down the pub HP is all people talk about but really torque is what you want to focus on.
We used to make the Ford Fiesta with 105PS and 130PS 1.8 engines. It was the same engine with different cam etc. I was in Cooling development at the time, so we used to go and do a lot of Hot Climate testing. My colleague who was responsible for the Fiesta tested them back to back and said he'd take the 105PS any day on the street. That 130PS was only got by moving the torque up the rev range. Away from the lights, on the street by the time you'd caught up in the 130PS it would be too late.
I later had an RS1800 Fiesta with that engine, and it felt like a turbo (not good!). There was nothing below 4000rpm, and I'd get beaten away from the lights by cars that I'd have beaten in the full quarter. By the time I was gaining on them it was all over on the street.
OK, I'm greedy - I want low down torque AND horsepower AND good ET's. This engine should give me all of them, but I will be sacrificing a little ET. But the engine will be more fun to drive, and FASTER, on the street where I will spend most of my time.
Dave you're right about the losses increasing at the square of engine rpm - another good reason to make your torque (therefore power) down low!
A broad torque curve is exactly what I want on the street. Down the pub HP is all people talk about but really torque is what you want to focus on.
We used to make the Ford Fiesta with 105PS and 130PS 1.8 engines. It was the same engine with different cam etc. I was in Cooling development at the time, so we used to go and do a lot of Hot Climate testing. My colleague who was responsible for the Fiesta tested them back to back and said he'd take the 105PS any day on the street. That 130PS was only got by moving the torque up the rev range. Away from the lights, on the street by the time you'd caught up in the 130PS it would be too late.
I later had an RS1800 Fiesta with that engine, and it felt like a turbo (not good!). There was nothing below 4000rpm, and I'd get beaten away from the lights by cars that I'd have beaten in the full quarter. By the time I was gaining on them it was all over on the street.
OK, I'm greedy - I want low down torque AND horsepower AND good ET's. This engine should give me all of them, but I will be sacrificing a little ET. But the engine will be more fun to drive, and FASTER, on the street where I will spend most of my time.
Dave you're right about the losses increasing at the square of engine rpm - another good reason to make your torque (therefore power) down low!
The book figure on mine is 175Lb/Ft at 3000rpm, 145hp at 5500rpm, when tuned the proportion of torque to hp stays about the same, but it peaks at 2500rpm/6000rpm respectively ...Yeah, it is like driving a 1.6 n/a at under 2500rpm when you first pull away 
You can go too far with making torque though, and end up with something like the 2.3 diesel Pug 504 my dad had - pulled like mad up to 3500 rpm, lol. That said those motors would do over a million miles with regular servicing 
You can go too far with making torque though, and end up with something like the 2.3 diesel Pug 504 my dad had - pulled like mad up to 3500 rpm, lol. That said those motors would do over a million miles with regular servicing -
Dave-R
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The drawback to making torque at lower rpms is it limits your speed. At least that is the way I see it.
Fine if you want power at street speeds but hopeless if you also want a high top speed. Those cars with a high power band you were driving did not have the right gearing for the engine. But then again you would not sell many cars that you had to rev the breasts off to go anywhere!
On the whole, for a performance car, it is better to make your torque at high rpms and then use gearing to limit your speed and give you huge amounts of torque at the wheels.
At the risk of teaching you how to suck eggs can I explain my view with some examples?
Say you have an engine making 400lbs of peak torque at 2000rpm. Its horsepower at that rpm would be (400 x 2000) / 5252 = 152hp. As it is peak torque at this rpm it will make more power at higher rpms until torque starts to fall faster than rpm is rising, and then HP will drop off very fast, limiting top speed. This it typical of a long stroke engine. The torque curve may be flatter and wider but it is all in the lower rpm direction and it drops off fast after peak.
Your speed at 2000 rpm with 3.23:1 axle gears and 235/60/15 tyres would be around 48mph. The torque at the rear wheels would be 3.23 x 400 = 1292lbs/ft of torque. Impressive at street speeds. But at higher rpm if there is no torque up there the amount of torque at the rear wheels will drop off quickly until there is not enough to push the car any faster. You might think that fitting taller gears will give it a higher top speed though?
No. Because fitting taller gears will reduce the torque at the wheels so there is even less power to move the car faster.
If we then look at another engine that makes the same 400lbs but at a higher 5000rpm. That engine is making 380hp. More than twice the power. In the same car it will have the same 1292lbs of torque at the wheels but be doing 120mph and yet have lots of rpm and power to go much faster than that.
But like you said. At lower street rpms it will accelerate more slowly than the first car until it gets up in the power band.
But what if we then stick 4.30:1 gears in the axle of the second car?
Well in this case although top speed is now 25% less (5000rpm is now 90mph) the amount of torque (at the wheels) at all rpms is 25% higher (1720lbs at 5000rpm).
The lower the gears in the axle the more torque is multiplied but the more top speed is limited. However if your engine is well built and makes peak torque at high rpm it will still have a strong top speed even with the low axle gears.
And then you fit the overdrive...
Fine if you want power at street speeds but hopeless if you also want a high top speed. Those cars with a high power band you were driving did not have the right gearing for the engine. But then again you would not sell many cars that you had to rev the breasts off to go anywhere!
On the whole, for a performance car, it is better to make your torque at high rpms and then use gearing to limit your speed and give you huge amounts of torque at the wheels.
At the risk of teaching you how to suck eggs can I explain my view with some examples?
Say you have an engine making 400lbs of peak torque at 2000rpm. Its horsepower at that rpm would be (400 x 2000) / 5252 = 152hp. As it is peak torque at this rpm it will make more power at higher rpms until torque starts to fall faster than rpm is rising, and then HP will drop off very fast, limiting top speed. This it typical of a long stroke engine. The torque curve may be flatter and wider but it is all in the lower rpm direction and it drops off fast after peak.
Your speed at 2000 rpm with 3.23:1 axle gears and 235/60/15 tyres would be around 48mph. The torque at the rear wheels would be 3.23 x 400 = 1292lbs/ft of torque. Impressive at street speeds. But at higher rpm if there is no torque up there the amount of torque at the rear wheels will drop off quickly until there is not enough to push the car any faster. You might think that fitting taller gears will give it a higher top speed though?
No. Because fitting taller gears will reduce the torque at the wheels so there is even less power to move the car faster.
If we then look at another engine that makes the same 400lbs but at a higher 5000rpm. That engine is making 380hp. More than twice the power. In the same car it will have the same 1292lbs of torque at the wheels but be doing 120mph and yet have lots of rpm and power to go much faster than that.
But like you said. At lower street rpms it will accelerate more slowly than the first car until it gets up in the power band.
But what if we then stick 4.30:1 gears in the axle of the second car?
Well in this case although top speed is now 25% less (5000rpm is now 90mph) the amount of torque (at the wheels) at all rpms is 25% higher (1720lbs at 5000rpm).
The lower the gears in the axle the more torque is multiplied but the more top speed is limited. However if your engine is well built and makes peak torque at high rpm it will still have a strong top speed even with the low axle gears.
And then you fit the overdrive...