quote Originally posted by rogergarrison: I have never seen a single rice racer car with ANY amount of horsepower towing a boat out to the lake. They park them and use dads V8 pickup or SUV.

so so true. even the ricers trailing their cars to the tracks...whats pulling their rice buggy?

the right tool for the right job.

First off most semi's are diesel. Have you ever seen a 6 cylinder in a semi? They are usually straight 6's because an in-line engine produces better low end torque than a V'd engine. Second the size of the 6 has more displacement than a lot of V-8's. The reason they use V-8's in smaller trucks for towing is because at low RPM the V-8 will produce more torque than a turbo 4-cyl. Yes the turbo 4 has more HP and torque, But in the 1000-2500rpm range a larger diplacement car wil provide higher torque. That is what gets the weight moving.
In terms of the semi's, they have 16 gears to be able to utilize all the torque to pull the lareg weight of a fully loaded trailer.
Also, Not all semi's are 6's, Some use straight 8's as well.
As an example a Mack Freightliner has 350hp @ 1800rpm and 1260 lbs-ft of torque at 1250rpm on a 720 cubic inch (which is 12.0L !! ) 4-valve per cylinder inline 6 cyl. The engine itself weighs 2190lbs.
Go to a friends house that has a 4WD truck and ask him to put it in 4-wheel Low. The truck won't go very fast, But it could easily drag a car. It is geared for pulling. Hence a Honda with a 4-cyl turbo at 400hp could not tow a 19ft boat as easily and a 350hp hemi truck. If the 4-cyl turbo was in the truck, It could tow the boat, but the engine would actually be straining more until the weight was moving only because moving weight requires X amount of power and the 4-cyl turbo would be at a higher rpm to attain the same minimum power level as the V-8. Yes the 4cyl turbo does make more power at peak and would be faster, However the larger displacement of the engine increases torque earlier make the weight easier to move.

This whole thread seems to be a mix of acceleration and pulling capacity. The reason a V-8 is better than a 4-cyl turbo for towing is the V-8 applies more torque at a lower rpm and can get the weight it is pulling to move faster. Low speed high torque is the key to towing heavy weights. High speed high horsepower is the key to winning a drag race.
These are two different purposes for two different engines. The V-8 hemi in a ram pick-up wasn't designed to go 0-60 in 4-seconds and the 4-cyl turbo in an import isn't for pulling a 19ft boat.
Everyone seems to be stuck on peak power which has nothing to do with towing capacity. It's the amount of power at a given rpm (and usually less than 2500rpm) that make pulling the weight easier.

[This message has been edited by Oreif (edited 08-05-2005).]

Ed

LOL, that made my day.................

Straight 6 motors do not produce any more torque than a motor in a V configuration. The only reason motors are made in a V is to save room. This is important when you have 8 cylinders and need to fit them in a passenger vehical but not important for a straight 6 diesel in a semi. A Cummins straight 6 turbo is 5.9L, not huge by any means and is a widely used motor from Dodge trucks to bulldozers. A Boxer engine is the most efficient design, opposing cylinders counteract their forces which means less friction loss on the bearings. This design is also large so is mostly used in 4 or 6 cyl configurations in sports cars. Also has the advantage of a lower center of gravity.

As for low end torque getting a load moving, well thats all dependant on the torque converter. If you have a higher stall converter on a motor with less down low torque, it will engage at a higher rpm to allow the smaller engine to get into its powerband sooner. Same with a motor with alot of torque, a low stall converter will lock up sooner to take advantage of the torque available.

You mis-read my statement. In-line engines produce more LOW-END torque than their V counterparts at the same rpm. NOT more peak torque. You keep referring to HP and Torque in terms of peak numbers. Yes a flat 4 or 6 will produce lots of low-end torque as well. This is why the 60's and 70's VW bugs launched of the line quicker than most muscle cars, But the 50hp wasn't enough to move the car very fast once it launched.

OK, lets look at swapping torque converters. With a V-8 lets say for purposes of our example, The converter stall speed is 1800 rpm and that the V-8 has 160 ft/lbs of torque at the same rpm. Now you want to pull a trailer of your drag race car to the track. Let's say the truck needs about 200 ft/lbs to keep the vehicle with trailer going 55mph. So the V-8 is running somewhere around 2400 rpm.

Now we take the SRT-4 engine and install it in the truck. Change the torque converter to a 2700 rpm stall so that at the stall speed the engine is producing 160 ft/lbs of torque. (for ease of our example). So now you need to wind up the 4-cyl turbo to 2700 rpm just to move the same weight. Time to get on the highway with the same load. At 200ft of torque, The smaller engine is now running about 3500 rpm.
Being it is a smaller engine and running at a higher rpm, the 4-cyl engine will run hotter and burn more fuel. Not to mention the trans is now running hotter as well, Transmissions hate heat.

So on a flat highway both vehicles are towing the same load. But wait, Now you come upon a 4% grade hill. Say for example it requires 250 ft/lbs of torque to pull the load. So in the V-8 truck you press the gas pedal and get the RPM's to about 2700.

Now the 4-cyl truck needs 4100 rpm to go up the hill. The little engine is now working twice as hard to pull the same load.

Wanna bet which engine is going to have more wear at the end of the drag race season? Wanna bet on which tranmission wears out first?

I suppose now you are going to bring up gear ratio changes , But remember as you lower the gear ratio you increase the amount or torque required to turn them. This may help the trans, But the 4-cyl engine is still working a lot harder than the V-8 and will wear out sooner over the years. Even if the 4-cyl truck has more peak power and in the 1/4 mile is faster it cannot tow the same weight as reliably as the V-8 truck.

Like I said, If XXX amount of weight requires YYY of power to move it, The V-8 will do it at a lower rpm and easier than any 4-cyl. Peak power doesn't matter at all for towing.

Can you explain the mechanics of this? Assuming the same number of cylinders, the same bore/stroke ratio, and the same displacement, why would cylinder arrangment make a difference? A moment diagram would be nice to help explain this.

JazzMan

Well, generally in-line engines have a longer stroke by design, But In your question you state they are the same so we'll go that way.
It is the crankshaft. The longer heavier balanced (larger counter weights) crankshaft is what makes the difference. It is like the difference between using a 4" screwdriver with a 1" diameter handle as opposed to using a 6" screwdriver with a 1.5" handle. You can get more torque from the longer, slightly larger diameter handled screwdriver. The problem with in-line engines is because of the larger diameter crankshaft, their max RPM is lower than V styled. More mass rotating at a lower rpm is where the higher low-end torque comes from.
The 4-cyl's use in-line design to keep up the torque due to smaller displacement.
A V-4 can spin up very easily but torque is lower.
Honda V-Tech engines have their counter weights a smaller diameter to gain more rpm and counter rotating shafts to aid in balancing the engine.
A flat designed engine uses counteracting forces of opposing cylinders to increase HP/torque as crzyone stated.

Sorry, I don't have any diagrams (and still cannot use PIP from home???)

[This message has been edited by Oreif (edited 08-07-2005).]

Not that I'm trying to disagree with you, but I'm almost positive that Cryzone was arguing that it could do it. And not that it would last, or be more reliable, or get better gas mileage. Just that it could do it. even if it was just once, and the motor blew up into 1,000 pieces, it could do it just once.

I'm just venturing a guess, but I'm told that inline 6 cylinder's run smoother with less NHV than certain V-engines, I'm not sure if that would help power down low, or just help the longevity of the motor.

I never said that the 4-cyl turbo couldn't do it, I just stated that the V-8 is better because the low-end torque is greater than that of a 4-cyl turbo, allowing the V-8 to move a specific weight faster and easier off the line and pull more weight at 55mph even though the 4-cyl turbo has higher peak HP/torque. Larger displacement engines produce higher torque levels at lower RPM's which is what you want when using the engine to tow or pull a heavy load.

Ok, when I said identical bore/stroke ratios and identical displacement and cylinder numbers, that means that the crank throw distance has to be the same since that determines stroke. With identical bore/stroke ratios, cylinders, and displacement, the stroke and bore will be identical between a V engine and an inline engine. Since the firing pulses will be equally divided on either engine into the same number of degrees, that means that other than counterweighting on the crank there isn't really a difference between a V and an inline engine.

So, the only real difference might be rotating mass, that acts as a flywheel and smooths out the power at the back of the crank. That does not mean more torque or power, up high or lower down, it just means that the power is smoother. Remember, the actual torque is a function of the crank moment, piston area, and cylinder count. The expanding gas pushes on the rod, that pushes on the crank, which makes the crank want to twist. The cylinder arrangement is not relevant to that at all.

I don't know why people continue to believe that a straight six has inherently more torque or low-end power just because it's a straight six. You could easily design a V6 to have identical low end power and torque as a straight six, there is nothing inherent with the cylinder layout that makes a difference.

My theory is that old inline engines tend to be based on old designs where long strokes were used to make up for other deficiencies, and because the long cranks in a straight six can't be spun very fast designers focused on low end torque because low end was all they were going to get out of that twisty and heavy crank. V designs, being newer and more modern with smaller, lighter, and stiffer cranks, can spin faster, and since horsepower is a directly result of RPM multiplied by torque, higher RPMs produce more power potential.

JazzMan

It's not that I'm disagreeing with you, I was just reiterating that it could be done. But yes, I do understand that it would not be better than a V8. just that it would be possible maybe at least once.

Engine layout has no bearing on torque. Only factors affecting torque is crank throw, cylinder bore and VE. Cylinder layout has nothing to do with it.

Rotating assembly of an engine works just like the the flywheel as the diameter and/or weight increase so does the amount torque applied at a lower rpm. If you have a large heavy flywheel on an engine, The torque applied at say 1500 rpm will be higher ft/lbs than an engine with a much lighter flywheel. Yes, the engine with the lighter flywheel will be able to run up to a higher rpm and thus make more peak power.
It's not so much as how much peak torque the engine has but more of where the max torque is applied in relation to the engines rpm that makes the difference between in-line and V engine designs.

The reason they tend to use longer strokes on in-line engines is to keep the length of the engine as short as possible (Larger bore = longer engine = longer crank, more susceptable to vibration/twisting as rpm increases) but increase displacement.

Again, Here is where the confusion seems to come into play. It isn't peak torque, but what the specific amount of torque is at a given RPM. Maybe it is the word "more" that is adding to the confusion.

A V-6 with 240 ft/lbs of torque may have it's peak torque around say 3500rpm.
an identical displacement in-line 6 may have the same 240 ft/lbs of torque, But because of the increased stroke and/or larger rotating mass the peak torque is down at 2500rpm. The inline engine would be able to tow more weight easier than the V styled engine but the V styled engine will be the faster (assuming both vehicles have the same weight/gearing/size/etc.) in the 1/4 mile. So engine layout does affect the torque's level of application along the RPM range.

So maybe stating that an in-line engine produces it's peak torque at a lower rpm than a V style engine of the same displacement would be correct?

Or in terms of this thread, A larger displacement engine (V-8 hemi) produces it's torque at a lower rpm than a smaller displacement engine (4-cyl turbo) there-by increasing it's ability to tow/move a heavier load easier?

[This message has been edited by Oreif (edited 08-07-2005).]

A Ram truck with a 350 hp Hemi pulling a 19 ft boat would accelerate faster on a 4% grade than a tuner car with a 400hp turbo pulling the same trailer because the truck is geared to utilize the available torque better with a heavy load.

A Ram truck with a 400hp turbo with everything else being the same could not pull the 19ft boat on a trailer and accelerate the same (or faster) because the gearing isn't set-up to utilize the engines torque properly.

A Ram truck with a 400hp turbo and geared properly for the engine could pull the 19ft boat (and most likely faster) but would be impractical for reliability.

I was using the flywheel as an example of the rotating mass of the crankshaft. You would then have the "stored energy" of the heavier/larger crankshaft, So the output of the engine's torque would increase earlier. (lowering the point at which the torque peaks.)

Actually a torque converter is set-up to engage at a specific torque level at a specific rpm, Not by RPM alone. So if you change the level of torque the stall speed changes. An engine with a higher torque output hooked up to a torque converter designed for a lower torque engine will actually raise (Corrected by Darth below.) the stall speed of the converter. When I ordered my torque converter for my 3.4L, In order to set the stall speed properly, They required the torque vs. RPM data because amount of torque at the required rpm is what the converter utilizes. So it wouldn't matter if it was stick or auto (assuming the converter is set-up for the engine's torque correctly)

[This message has been edited by Oreif (edited 08-07-2005).]

With all due respect, I have to disagree with this one statement. Stall speed of a torque coverter will be dependant on the amount of power going thru it. If your statement were true, as you worded it, your torque converter would stall higher at lower throttle openings than it would at WOT (in other words, ANY torque coverter would stall lower with the more power you put thru it). This simply isn't the case and I can prove this using my car as an example.

I am using the torque coverter from a 3800 n/a powered car. According to the ID sticker, my torque coverter is supposed to stall at approx 1800rpm with the 3800 n/a engine that produces about 230 ft/lbs of torque. My turbocharged engine puts out about 450 ft/lbs of torque at full boost. If I power brake my car, the stall speed of the torque coverter initally appears to hold at 1800rpm UNTIL the boost comes up, at which point this raises the stall speed of the coverter to about 2600rpm before the brakes can no longer hold the car.

Same thing goes for other cars. If you take a torque converter that stalled at 2800rpm behind a 4cyl making about 120tq and put it behind a 2.8 producing 180tq at the same RPM, the torque converter would stall much higher, assuming the 2.8 could maintain the higher torque output at the higher stall speeds. Stall speed of a TC depends on the torque output AND torque curve of an engine. This means if I took a TC that stalled at about 2000rpm behind a 2.8 producing 180tq @ say 2000rpm, and installed it behind a 3.4 DOHC that produces 215tq @ 4000rpm but only produces say 100tq @ 2000rpm, the stall speed will be lower because the DOHC engine cannot put out as much power as the 2.8 at the lower RPM's, thus the TC won't have as much power going thru it and stall speeds will be lower.

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power corrupts. absolute power corrupts absolutely.

Custom Computer Tuning | Engine Conversions | Turbocharging | www.gmtuners.com

Oop's my mistake.
Yes, you are correct the brake stall speed will be higher not lower.

(changed and credited the correction to the original post.)

[This message has been edited by Oreif (edited 08-07-2005).]

With regards to this thread, Does everyone agree with the below statements?

A Ram truck with a 350 hp Hemi pulling a 19 ft boat would accelerate faster on a 4% grade than a tuner car with a 400hp turbo pulling the same trailer because the truck is geared to utilize the available torque better with a heavy load.

Disagree, which is what our argument is all about I believe

A Ram truck with a 400hp turbo with everything else being the same could not pull the 19ft boat on a trailer and accelerate the same (or faster) because the gearing isn't set-up to utilize the engines torque properly.

Agreed, as the gearing/converter won't be optimal.

A Ram truck with a 400hp turbo and geared properly for the engine could pull the 19ft boat (and most likely faster) but would be impractical for reliability.

Tough call.. Hard to say with this fictional motor.

I thought it was if a 4cyl tuner car could do the same thing as the 8 cyl hemi. I think not, I say no because tuner cars are setup for top speed not torque. They are also lightweight and FWD I just don't see a tuner car pulling a 19ft boat up a steep incline. Oh sure you can special build a configuration using a 4 cyl that could do it at least once. But how would that car and setup fair against the other tuners cars with normal setups? In other words I see it as basically a purpose built one trick pony.

[This message has been edited by Unrivaled (edited 08-07-2005).]

Me and the Old Man are working on the project. Here's the link if you care.
https://www.fiero.nl/forum/Forum2/HTML/064826.html

We start talking about this thread and all the good and bad info on it. Then I toss this one out. In a Sport Compact Car issue I see this Supra with a 3L 1339hp and 994ftlb torque (6 banger though) 1/2 the Cubic inches of my Dads truck. I maybe full of it but with that kind of power and torque, it is 4X the HP and 3X the torque, It would have to be able to pull that boatload up that bridge without a prob.

I am going with an 8 in the Fiero
Bonzo

It would not be correct to say that identical displacement engines with the same bore and stroke ratio would produce different torque at different RPMs just because of cylinder layout. This is a math problem. As far as rotating mass affecting the amount of torque, no, that's not the case. It will affect the smoothness of the torque, but will not add any addtional torque. If it did, then all people would need to do is add a 5,000 pound rotating assembly to get huge amounts of torque out of tiny engines. In other words, a perpetual motion machine.

If you want to say that inline sixes tend to be designed with longer strokes and smaller bores and therefor produce more torque, that's fine because it's correct. If you want to say that an inline six produces more torque just because it's an inline six, then that would be incorrect.

Regarding rotating mass, the cylinders firing store energy in the rotating mass. When the rotating mass is connected to the drive wheels the stored energy moves the car forward initially. However, the power used to accelerate the car is mostly from the pistons, not the stored energy in the rotating mass. If you take a V engine of equal displacement and bore/stroke ratio as an inline six and add and equivalent mass of flywheel as the extra crank of the inline six, then the acceleration, towing, and cruising behaviour will be the same as the inline six.

JazzMan

I'm not to sure why you chose that quote of mine with the above statement, but, I'm saying a 4 cylinder turbo truck (TRUCK) could do it, not a econobox car. I personally believe that the original statement was more directed towards the engine being able to do it, not the car itself.

I mean honestly, what person really compares a car to a truck for towing? (given the context of the original statement) I think Bonzo's dad here was really aiming at the engine itself.

I think that sounds about right.

sorry but flywheel weight ha snothing to do with rpm - only with acceleration - it takes longer to accelerate a heavy flywheel -
yes the its also more difficult to slow down a heavier flywheel making it easier to get going without stalling but that does not equal dynamic torque - just stored energy.
a lighter flywheel won't store up as much energy but it will also free up the engines power output

as for an inline engine making more torque - you are the only one thats mentioned PEAK torque - everyone else keeps telling you that given the same bore/stroke and VE that the inline and V will have identical outputs THE WHOLE RPM RANGE

do inline 4's produce more low end toque? no because it has nothign to do with inline or V setup - its all in the rod length, head flow, and cams

agreed. A balanced flywheel will have nothing at all to do with RPM's...

bump

The idea that diesels are inline in heavy trucks is only true for the last 15 years or so. Detroit sold millions of V arrangement engines in the 6V71, 8V71, and 8V92 series for 30 years and they were quite successful. Cummins also made a couple of V8 engines. The 555 was a failure in the market and in practical use because of it's tendency to swallow valves, the 903 was a practical success but never marketed well because the Cummins market just couldn't get used to the idea that a V8 in a Cummins diesel would work. I had a couple of 903's in tractors, one turbo'd and one naturally aspirated, and both were good engines for me. They also had a higher torque rise than the 855 inline six cylinder and, at the time, produced about 35 more hp in their highest horsepower configuration. The Detroits, even though V8's, are not high rpm motors. The 8V92TTA in my one semi only runs to about 2300 rpm governed because of a fairly long strong, and that's in spite of the fact that it's a two stroke engine.

V or Inline cylinder arrangement has nothing to do with the torque output of the motor, there are many other factors that determine that and bore/stroke ratio as well as total stroke are what determine where and how much torque and engine can produce, for the most part.

John Stricker

89 volvo 745 turbo ic wagon

loaded with 3 N* motors and a getrag and a lot of other stuff in the wagon
I towed a fiero from mid louisiana to miami at about 80mph avg

the trick the volvo uses is a small turbo that boosts tork down low
that gives a flat curve to both tork and hp from 2000 to 5000rpm

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Question wonder and be wierd
are you kind?

Yeah the RICERS on here would be JACKING OFF ALL DAY.

MMMMM high reving engine.

so liking an engine with a high redline makes someone a ricer now?

quote Originally posted by Kohburn: so liking an engine with a high redline makes someone a ricer now?

I was thinking the exact same thing

Of course... Having an engine that runs out of breath down low makes you a real tree chopping, burly, unshaven, flannel wearing man.. Didn't you know?

I just browsed through the thread quickly so this may have been mentioned, my bad. It seems the truck/V8 at 30% throttle would be much more streetable than the turbo 4 only running at 5-8psi cruising at 30% throttle. OR are you guys saying that by running the car at 75% throttle while the truck at only 38% throttle would be irrevalent because they will still be pulling the load either way...?

a turbo can run full boost at part throttle if the engine doesn't accelerate fast enough - wonderful thing about turbos is they only add HP when the engine needs the help - I would expect improved fuel economy with a boosted small displacement v6 towing than with an equivalent hp v8

It originally started with us saying 400tq in a 4cylinder will pull better than 350 tq in a hemi.. It has since escalated

Errr no it was actually 375 torque in the hemi just a difference of 25 lb/ft.

[This message has been edited by Unrivaled (edited 08-12-2005).]