Knowledge about stroking needed
Thread Starter
Cruising
Joined: Sep 2002
Posts: 14
Likes: 0
From: Easton CT
Knowledge about stroking needed
I'm trying to understand more about stroking. I'm confused and it would be great if someone can share a site that explains in DETAIL all the ins and outs of 'tuning' or 'modding' an engine.
From what I understand, there are two ways to achieve a certain cubic inch displacement (CID). You can bore the hell out of the cylinders and have a short stroke, and you can leave your cylinders and have a long stroke.
Which is better for what? I don't plan on racing past 160mph so... I guess a torque curve would be best suited for me?? I dunno. Opinions? Which is more reliable? Burns less oil? I'd like to learn EVERYTHING about this subject...not just minor details :rolleyes: plz.
thx! :D
From what I understand, there are two ways to achieve a certain cubic inch displacement (CID). You can bore the hell out of the cylinders and have a short stroke, and you can leave your cylinders and have a long stroke.
Which is better for what? I don't plan on racing past 160mph so... I guess a torque curve would be best suited for me?? I dunno. Opinions? Which is more reliable? Burns less oil? I'd like to learn EVERYTHING about this subject...not just minor details :rolleyes: plz.
thx! :D
Melting Slicks
Joined: Apr 2001
Posts: 3,034
Likes: 125
From: NY-South Florida
Re: Knowledge about stroking needed (MilYellow02)
One big advantage of an "all bore" motor is that the cylinder head combustion chambers can be opened up to allow better flow around the valves. This is refered to as "unshrouding" the valves. If you just bore the motor you can save $2K on buying a crank but will be spending between $ 1,800-2,300 for resleeving and $ 800-1,100 for new pistons. If you go the stroker route you will probably end up buying new rods and new pistons with the new crank. No sense going that far and leaving the stock parts!
Either way you better be saving. I am just about ready to assemble a 418 motor that I have about $ 11K into it. You want to play you got to pay!! :lol:
Either way you better be saving. I am just about ready to assemble a 418 motor that I have about $ 11K into it. You want to play you got to pay!! :lol:
Le Mans Master
Joined: Aug 2001
Posts: 6,071
Likes: 296
From: Savannah GA
Cruise-In IV Veteran
Re: Knowledge about stroking needed (9D9LS1)
Putting a 388 All-Bore in mine next week. Thought about putting a crank in while the engine is out but decided 388+progressive nitrous should be enough for me. ;) But the above post is correct. If you had to choose one or the other I would go all bore to help unshroud the valves.
[Modified by C5-VERT, 12:47 AM 10/3/2002]
[Modified by C5-VERT, 12:47 AM 10/3/2002]
Le Mans Master
Joined: Jun 2000
Posts: 5,555
Likes: 9
From: Indiana
Re: Knowledge about stroking needed (Tommy2times)
In general increasing the stroke gives you more low-end torque (at the expense of fast revving) and increasing the bore gives you faster revving at the expense of low-end torque. Choosing one over the other requires knowing what you want to use it for. Low-end torque is pretty useful on a drag strip, but faster revving may be better for a road course.
On the other hand, there are ways of making more power without doing either of these expensive modifications ... so the next question is .. how much power do you want to make, and how deep are your pockets?
On the other hand, there are ways of making more power without doing either of these expensive modifications ... so the next question is .. how much power do you want to make, and how deep are your pockets?
Team Owner
Joined: Jul 2001
Posts: 21,365
Likes: 996
From: Various places in Southern California.
Re: Knowledge about stroking needed (Tommy2times)
Other things being equal, a longer stroke improves power at lower RPM levels, but reduces the ability to rev, as it increases piston speed at any given RPM. A larger bore still allows higher RPM power increases. If the goal is any sort of racing use, the bore is probably the way to go. If the car is mainly a street car, higher RPM performance is likely to be less important.
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Le Mans Master
Joined: Jul 2000
Posts: 7,758
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From: Fort Worth Texas
Cruise-In II Veteran
Cruise-In III Veteran
Re: Knowledge about stroking needed (Tommy2times)
In an optimal situation with optimized gearing on both sides of the fence, an all bore will dominate a similarly displaced stroker on the drag strip. Because HP is what counts.
Its hard for many people to understand that HP and TQ are not opposing or seperate things. HP defines the work ability of TQ, and how effective it is at doing work. Remember all the TQ in the world can do no work without movement (RPM), and the result of how well it does that is called HP.
HP over TQ means you can do more work in less time. (for example racing).
TQ over HP means you can do even more work, but with the sacrifice of more time. (for example, stump or trailer pulling).
With that said, a street car requires a balance of both driveablity, and practicality. This is why many like the feel and usefulness of low end TQ. But on the dragstrip where your 99% of the time at high RPM WOT, requirements are somewhat different.
Obviously the best solution is bore and stroke.
Its hard for many people to understand that HP and TQ are not opposing or seperate things. HP defines the work ability of TQ, and how effective it is at doing work. Remember all the TQ in the world can do no work without movement (RPM), and the result of how well it does that is called HP.
HP over TQ means you can do more work in less time. (for example racing).
TQ over HP means you can do even more work, but with the sacrifice of more time. (for example, stump or trailer pulling).
With that said, a street car requires a balance of both driveablity, and practicality. This is why many like the feel and usefulness of low end TQ. But on the dragstrip where your 99% of the time at high RPM WOT, requirements are somewhat different.
Obviously the best solution is bore and stroke.
Melting Slicks
Joined: Sep 1999
Posts: 3,292
Likes: 0
From: Round Rock, Texas Texas
Re: Knowledge about stroking needed (kewlbrz)
HP over TQ means you can do more work in less time. (for example racing).
TQ over HP means you can do even more work, but with the sacrifice of more time. (for example, stump or trailer pulling).
With that said, a street car requires a balance of both driveablity, and practicality. This is why many like the feel and usefulness of low end TQ. But on the dragstrip where your 99% of the time at high RPM WOT, requirements are somewhat different.
Obviously the best solution is bore and stroke.
TQ over HP means you can do even more work, but with the sacrifice of more time. (for example, stump or trailer pulling).
With that said, a street car requires a balance of both driveablity, and practicality. This is why many like the feel and usefulness of low end TQ. But on the dragstrip where your 99% of the time at high RPM WOT, requirements are somewhat different.
Obviously the best solution is bore and stroke.
Safety Car
Joined: Nov 1999
Posts: 3,891
Likes: 2
From: Houston, TX
Re: Knowledge about stroking needed (kewlbrz)
Very well said Kewlbrz! You have my vote. :)
Bore before stroke, but either one is an improvement. :)
As the old saying goes, "Torque sure does feel good, but Horsepower is still king!!!"
Bore before stroke, but either one is an improvement. :)
As the old saying goes, "Torque sure does feel good, but Horsepower is still king!!!"
Race Director
Joined: Mar 2000
Posts: 17,602
Likes: 20
From: Palm City Florida
Re: Knowledge about stroking needed (kewlbrz)
Its hard for many people to understand that HP and TQ are not opposing or seperate things. HP defines the work ability of TQ, and how effective it is at doing work. Remember all the TQ in the world can do no work without movement (RPM), and the result of how well it does that is called HP.
And a great example of this is a duramax
The Duramax Diesel 6600 has best-in-class power and performance with the segment's highest horsepower and peak torque ratings. Ratings are 300 horsepower @ 3,000 rpm and 520 lb-ft of torque @1,800 rpm. It's high, flat torque curve will deliver more power across the power band than any competitor, and will help Duramax Diesel 6600-equipped GM HD pickups excel in off-the-line performance, acceleration and heavy-duty trailering and hauling.
This motor would not get you very far in the 1/4... :smash:
Instructor
Joined: Dec 2001
Posts: 182
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From: TARZANA CA
Re: Knowledge about stroking needed (Tommy2times)
A good place to "start" learning about tuning and moding is John Lingenfelter's book -
John Lingenfelter on Modifying Small-Block Chevy Engines. IMHO. :flag
John Lingenfelter on Modifying Small-Block Chevy Engines. IMHO. :flag