You have to remember that if you are going to try & optimise traction that the actual point of best traction is somewhere in between where the tire actually starts to spin and where it starts to 'boil' rubber, so rather than speed differential between L&R or F&R you need a sensor that measures the difference between tread surface & the rate of travel over the road/terrain, and factor in the best 'difference' for the tire compond & surfaces in use. IIRC the current production car setups only act on a speed differential between tires with fair bit of leeway to accomodate the average driver.
What's the point of a high revving LSx?
- Thread starter bzinsky
- Start date
this is really good to know actually. Without sounding like a wimp, getting hurt in one of these things was a concern of mine. I've driven so many factory traction control systems which engage far too late and are not smooth at all.
I think that is true for drag racing but not traditional racing.
The as soon as your tires break traction. They have no idea what direction they are supposed to go. It's sort of tough to explain without visualization. In drag racing this does not matter as your are going in one direction. In circuit racing there are 2 dimensions, once you slip the tire, it is no longer trying to pull a certain direction, it is simply trying to resist going where it is going.
Best example is braking. once you lock the brakes, you have no control over direction. Let pretend that your braking system, instead of abs, it simply makes the tires spin 10mph slower than your car is moving. You will still have no control over your vehicle as the tires are still skidding.
Essentially, any break in traction is bad for lap times, but not drag.
Not correct, do some research into tire slip angles and 'circle of traction'. Everything has an element of compromise in it when it comes to tire contact.
Even the Drag Racer case has that as they use clutch slip to balance power vs traction.
But your initial post had some thoughts to kill off some torque in order to make life easier on the transaxles, I know of at least one transaxle vendor on this website who would have been happier if the end user's had shown similar compassion for his product
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Even the Drag Racer case has that as they use clutch slip to balance power vs traction.
But your initial post had some thoughts to kill off some torque in order to make life easier on the transaxles, I know of at least one transaxle vendor on this website who would have been happier if the end user's had shown similar compassion for his product
.I am building a high revving LS engine for the sound and feel. It should have a pretty nice long power curve. I plan to build it to rev to 8500 or even 9000 rpm if I want. Is it cheap, heck no, ti valves, etc add up. I am also doing a flat plane crank with 3.00" stroke. It should be interesting. The reason why I am doing it? The SLC is my dream car and to me the sound and feel of the engine are super important to my grin factor when driving. Plus I like the challenge of building it.
Terry Oxandale
Skinny Man
I had a 240Z with a 289 (high rev'r), and thought that was a good set-up, especially for a 50/50 weight distribution in a light car. The intent was accomplished by having the torque come on when I could use it, and stay there long after I'd be required to shift to the next gear. It sounded good, lumpy cam and all. Then...
...I put a stroked 351W (383) in it, and Lord only knows how much fun I found I was missing out on. I found out that I'd much rather use the right foot as the torque control versus the short stroke/high rev configuration. I'll probably never go back to that short stroke configuration again. The car went from being a little tornado to a full blown stump-pulling hurricane.
...I put a stroked 351W (383) in it, and Lord only knows how much fun I found I was missing out on. I found out that I'd much rather use the right foot as the torque control versus the short stroke/high rev configuration. I'll probably never go back to that short stroke configuration again. The car went from being a little tornado to a full blown stump-pulling hurricane.
Definitely sound. A nicely tuned high-rev'ing V8 is pretty sweet.
[ame=http://www.youtube.com/watch?v=68wGJ8zQ7ys]F355 great sound V8 ferrari - YouTube[/ame]
Here's a modest/muted sounding V8 in a small car:
[ame]http://www.youtube.com/watch?v=qKmuZ87rGzI[/ame]
You can also get more hp out of a high rev'er v. low revs, everything else (ie. displacement) being equal. It's just that simple. Sure, you'll get more torque out of displacement, but if you want to keep weight down and aim for fuel efficiency then small and high-revs are a good route.
As the owner of a still born flat-crank high-rev'ing V8 project, I've spent some time thinking on the subject. More low down torque is not always good - a light car only needs so much of that. A wide power band can be nice for daily driving (less shifting) and a high rev'ing engine with reasonable power throughout the range can dish that up pretty well.
Maybe the attention given to getting some more revs out of an LS engine is just simply something fun to mess with...with an engine that is basically a pretty great engine with a large following. In other words, there's a whole lot of gear-head folks to relate to when it comes to monkeying with an LS engine, which is fun and enjoyable in itself.
Just as a side note, I was in the ferrari store in San Fran a few weeks back and they have an F1 crank out on display...looks like a chunk of aluminum round stock - there's hardly any crank throw at all!
[ame=http://www.youtube.com/watch?v=68wGJ8zQ7ys]F355 great sound V8 ferrari - YouTube[/ame]
Here's a modest/muted sounding V8 in a small car:
[ame]http://www.youtube.com/watch?v=qKmuZ87rGzI[/ame]
You can also get more hp out of a high rev'er v. low revs, everything else (ie. displacement) being equal. It's just that simple. Sure, you'll get more torque out of displacement, but if you want to keep weight down and aim for fuel efficiency then small and high-revs are a good route.
As the owner of a still born flat-crank high-rev'ing V8 project, I've spent some time thinking on the subject. More low down torque is not always good - a light car only needs so much of that. A wide power band can be nice for daily driving (less shifting) and a high rev'ing engine with reasonable power throughout the range can dish that up pretty well.
Maybe the attention given to getting some more revs out of an LS engine is just simply something fun to mess with...with an engine that is basically a pretty great engine with a large following. In other words, there's a whole lot of gear-head folks to relate to when it comes to monkeying with an LS engine, which is fun and enjoyable in itself.
Just as a side note, I was in the ferrari store in San Fran a few weeks back and they have an F1 crank out on display...looks like a chunk of aluminum round stock - there's hardly any crank throw at all!
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if you want to keep weight down and aim for fuel efficiency then small and high-revs are a good route.
Not sure I agree with this - small engine making power at big revs means lots of duration on the cam, which tends not to reward the driver with great mileage, even when driven slowly. They have great VE at high revs (which is what makes the power), but not so great VE at cruising revs, unless you have a VTEC or such system.
Corvettes are hard to beat on mileage, especially when considering the power they make.
Not sure I agree with this - small engine making power at big revs means lots of duration on the cam, which tends not to reward the driver with great mileage, even when driven slowly. They have great VE at high revs (which is what makes the power), but not so great VE at cruising revs, unless you have a VTEC or such system.
Corvettes are hard to beat on mileage, especially when considering the power they make.
Terry Oxandale
Skinny Man
And the weight of the LS series motors is very favorable. When I got the crate LS2, plastic intake, no ancillary parts, no flywheel, no exhaust manifolds, it weighed 345 lbs. Putting one together, the crank felt like it was the heaviest part of the entire motor.
This is one of the most misunderstood concepts amongst car enthusiasts. Many auto journalists simply don't understand it and perpetuate the myth that torque and power are fundamentally different things.
If anyone wants to test their (and my) understanding, I put this together.
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And somebody is going to say, Oh my gosh, look at that torque band, they don't have to shift so many times. But if you will look at the HP curve compared to the TQ curve, the HP curve follows the TQ curve and probably extends beyond by a noticeable degree, so you could say, oh my gosh, look at that HP curve, they only shift so many times.
Because there is no computational formula for TQ that includes time, again what we operate in, from here to there, it is 'potential'.
The word power in the general sense is even defined as a unit of measure in time.
TQ in and of itself means nothing, it is a static measurement, only when it contributes energy that can be measured in time is it useful by definition in the form of horsepower. It is a part of horsepower.
Because there is no computational formula for TQ that includes time, again what we operate in, from here to there, it is 'potential'.
The word power in the general sense is even defined as a unit of measure in time.
TQ in and of itself means nothing, it is a static measurement, only when it contributes energy that can be measured in time is it useful by definition in the form of horsepower. It is a part of horsepower.
I think that the major issue to people's understanding is that they confuse maximising torque (and power) at the wheels with that at the crank.
Question for everyone. Wouldn't you have to de-stroke the LS(x) to get it to rev higher as well? I think I read as much somewhere or another.
My 2 cents. No and Yes, depends on how high and what configuration. The cam will dictate how much rpm it will want to rev assuming it can flow the air at those rpms. I am doing a 3.0" stroke with 6.560" C-C on the con rods. My piston speed is 4525 at 9050rpm. If you have a stock 3.622 stroke you would have that same piston speed at 7500. With a 4" stroke it would be around 6700 rpm. Hence why large stroke engines do not usually rev high. People say to keep it below 4500 for less stress. This is assuming you upgraded items like con rods. People rev LS's to 7000 all day and that is easy. The hard part is all in the valve train with lightweight everything and valve spring pressures to not get float and then good rockers, etc. 7000rpm valve springs are like 100/300 and if you want to rev to 9000 you need like 300/600+. It gets crazy out of hand to rev them high, but oh it can be fun when you do.
It's all about application and combination. Weight, type of racing vs. street driving, track, gearing, tire diameter, etc. There is no one size fits all. All things being equal though, the big motor usually wins. Many serious motors have both: Big cubes & rpm.
A good buddy of mine is probably one of the pioneers of de-stroked high revving LS engines. He found the rpm limit of factory GM Ls1 ecus and was spinning his de-stroked ls7 past 10k rpm many years ago. You should ask him how often he is checking and changing valve springs. It's not cheap, and it's not very street friendly in terms of reliability and longevity. It sounds INSANE and his car is extremely quick because he meticulously designed every detail to work together.
I'm the last person to tell anyone this or that "isn't necessary" as I do things that aren't necessary all the time with my build. However we should really look at the facts, and do what we want because it's what we want.
My "big block" LS equipped SLC has over 500ft lbs of torque at the wheels by 1500rpm and is easily drivable. It sounds wicked at 7300rpm too. It's pretty fast, and can snap your neck if you want it to.
There is something to be said about a 6k rpm power band. I enjoy that more than a high winding 2 stroke type power band personally. But if we all liked the same thing, the world would be pretty boring.
Some of these posts regarding hp vs. tq have me scratching my head.
A good buddy of mine is probably one of the pioneers of de-stroked high revving LS engines. He found the rpm limit of factory GM Ls1 ecus and was spinning his de-stroked ls7 past 10k rpm many years ago. You should ask him how often he is checking and changing valve springs. It's not cheap, and it's not very street friendly in terms of reliability and longevity. It sounds INSANE and his car is extremely quick because he meticulously designed every detail to work together.
I'm the last person to tell anyone this or that "isn't necessary" as I do things that aren't necessary all the time with my build. However we should really look at the facts, and do what we want because it's what we want.
My "big block" LS equipped SLC has over 500ft lbs of torque at the wheels by 1500rpm and is easily drivable. It sounds wicked at 7300rpm too. It's pretty fast, and can snap your neck if you want it to.
There is something to be said about a 6k rpm power band. I enjoy that more than a high winding 2 stroke type power band personally. But if we all liked the same thing, the world would be pretty boring.
Some of these posts regarding hp vs. tq have me scratching my head.
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