Bike engine ideas. Don't pay attention to me :P

[Careless]

Looks like some good stuff. Thanks for the info.

 

The timing options I was talking about. Yes it's crude, but hopefully you'll all get it.

 

Note that this is JUST using OEM firing orders. This is the common 4 cyinder firing that I've seen almost all 4 cylinders use. I couldn't find the hayabusa firing order in a quick search, but I'm sure the info is out there. I'd imagine it'd be the same.

 

the bottom left one doesn't have a second cylinder, but another 4th cylinder.

is that a common misfire?

[ndeli55]

if going down this road, why not get two kawasaki h2s, bond them together, they were an old 3 banger two stroke from the seventies. could get to around 1400cc inline 6 and it would be a two stroker and would sound wicked, and would have some major power potential, plus the blue smoke rolling out the back would be a blast.

 

alternatively a couple of rz 500s would be cool, v4 2stroke water cooled engine. this would yeild a scary sounding 1000 cc z. hell while we are at it just get 3 banshee engines, put the 750 cc big bore kit on em and go to town. 2250 cc inline six mean machine. someone do it please.

[ndeli55]

never mind, just read the previous post about h2s

[Gollum]

the bottom left one doesn't have a second cylinder, but another 4th cylinder.

is that a common misfire?

 

Woops. Yea, the farthest right 4 should be a 2.

 

 

Thanks for the participation thus far guys. Got some pretty good input and ideas thus far.

[Six_Shooter]

Looks like some good stuff. Thanks for the info.

 

The timing options I was talking about. Yes it's crude, but hopefully you'll all get it.

 

 

Note that this is JUST using OEM firing orders. This is the common 4 cyinder firing that I've seen almost all 4 cylinders use. I couldn't find the hayabusa firing order in a quick search, but I'm sure the info is out there. I'd imagine it'd be the same.

 

You're thinking WAAAY too far into it.

 

You use two completly seprate ignition systems, and use the stock firing order for each engine.

 

I also don't think using motorcycle engines would give the desired outcome, due to usually very low torque output. Remember HP doesn't move vehciles, torque does. Horse power just determines how fast it could move the vehicle.

[Gollum]

You're thinking WAAAY too far into it.

 

You use two completly seprate ignition systems, and use the stock firing order for each engine.

 

I also don't think using motorcycle engines would give the desired outcome, due to usually very low torque output. Remember HP doesn't move vehciles, torque does. Horse power just determines how fast it could move the vehicle.

 

I truly beg to differ about the torque issue.

 

Trust me, I love torque, and I agree that in many cases a car without enough torque for the weight of the vehicle isn't fun.

 

But HP IS TORQUE. Why people talk about wanting one more than another is nonsense. A high RPM motor is going to be a low torque motor, and a high torque motor is going to be a low reving motor. It's that simple.

 

HP is RPM x Torque / 5252

 

HP is how much work will actually get done. Having lots of torque just means you'll get it done at lower RPM.

 

What matters isn't how much torque you have, it's the TORQUE CURVE.

 

The curve of the torque will give you an insight into the usible power range.

 

A flat curve like a honda yeilds a very liniar power band that gives you a motor that makes more power as you rev it. As long as it gets air it's happy and will just keep on making more power since the torque just doesn't fall off. (until around 10k when the cam dies).

 

A 440 mopar has a very high offset curve that starts huge, and drops off to next to nothing past 4k. This is great for towing, or if you want to do burnouts all day long. Or if you want to have 400hp on tap while cruising down the freeway. But these motors can actually tend to be more "peaky" than people generally think. The reason I say this is because once power starts to drop it DROPS. So you get a good strong bottom end, and it revs up, and then dies. While it's in it's happy RPM range it's great though.

 

 

The answer to ANY torque/hp curve is gearing. You want to shift from the top of your curve to the bottom of your curve. The longer you can make that curve the better.

 

Here's the dyno of the H1 V8, and since it has only 2.8 liters with a short stroke, it can't physically make huge torque, and relies on RPM to make it's power.

 

 

Look at how beautiful that torque curve is. Don't look at the number, look at the curve. It bubles up perfectly and still allows the motor to maintain a liniar performance in the rest of the powerband making it a very VERY versatile motor.

 

My friend chris here on this board (rudypoochris) did an article on this subject on his site.

 

http://www.autolounge.net/tech/hptq.html

 

Please read it and understand I agree, which means in most cases I'd say torque is very important. But it must all be taken in context and that it's about RPM range as well. You want to spend the most usible time in your RPM range as you can, and the bigger you can make it the better, regardless of torque numbers.

 

 

====================

 

And regarding the enginer management. It's been discussed in other threads, that it's better to use two independant systems than one giant system. This is how many V8 engines actually run, two totally seperate ignition systems, one running one bank, one running the other.

 

There shouldn't be a problem running two systems on two engines. It's been done in the past with success.

[Six_Shooter]

Yes, HP is a calculation of torque over time, but there are couple ways to gain more HP, which you have eluded to.

 

You can take a low torque engine and theortically continually rev it higher and higher, and as long as the torque outputs stays linear, HP output increases. The other way is to increase the torque output, and becaue HP is simply a calulation, this autmatically increases HP, at lower RPM.

 

Also most bike engines that I see have very low torque output, but rev like ll get out, to get the HP numbers. Bikes are very light, in comparison to even the S30, most superbikes are in the 400 to 500 lbs range, and that can even be considered heavy, especially when compared to a race prepped bike that seem to come in at between 300 and 400 lbs (sans rider of course, since there's too much of a variable there, and can quickly become a 50% weight increase of race weight, compared to much less percentage of a driver's weight effect on a car). An (early) S30 weighs just shy of 2500 lbs from what I have read, which is 5 times the weight of many bikes, that puts a hell of a lot of strain on the engine, when asking it to pull that much more, even using two, you are still asking it to move 2 and a half times the weight on each engine. I can only see this ending in disapointment, unless all you want is a high speed, WOT machine, like a Bonneville record chaser. I can't see this working well for any other application, even something like the Silver state run, which is mostly just high speed, but there are still corners that have to be slowed down for, and accelerated from. The low torque output engines seem to lack any of that quick get up and go that is need for these type of acceleration times.

 

A high reving, low torque engine could be used, but would not accelerate very well, from a standing start, or even low speed, as that is where high torque production is desired, and where many bike engines seem to faulter, again, because they are designed to pull light machines.

 

Yes, gearing can change the wheel torque, but all it can do is multiply the existing torque. I guess the only saving grace here is that you can use such a steep final gear that you can stay with in teh power band of some of these higher reving Super bike engines, turning 14000+ RPM.

 

I would just rather start with something that makes more torque to begin with as it's that much easier to get the HP out of it, take a high torque producing engine and build it to rev like a bike engine, yeeee haaaaw.

There are big block V8s that rev into the 5 digit RPMs, takes some effort, but is getting to be more commonplace, especially inthe drag racing world. I have heard of some Bonneville car builders trying similar ideas and being succesful with it, getting more RPM, with high torque means that the car will be able to accelerate to a higher speed, than a car with an engine that produces less torque.

 

Also many of the components are very light weight, and may not stand up to the abuse of trying to move that much more weight.

 

Don't get me wrong, I like smaller engines, in fact I'll be attempting to use a 3.5L V6 in my S30, that is generally considered to be of "less than desirable design", but very few people have actually tapped the potential of the engine, and have many people suggesting that I just start with an LSx, but I don't want to be just another "me too". This is an interesting idea, I just believe that the outcome will be less than desirable results.

[Gollum]

I agree that this would be a bad idea in a 2500 pound car

 

An (early) S30 weighs just shy of 2500 lbs from what I have read

 

But most of the 240Z cars actually weight in closer to 2100 in stock form.

 

There's a thread with weights posted.

 

http://forums.hybridz.org/showthread.php?t=101797

 

Note tube80z's post. In GT-2 spec he's at 1850. That's with a 280Z motor. I'm sure he's also got a built to spec cage too.

 

If I were to do this the goal would be on a very very stripped out 240Z with only a basic 6 point cage, as much lexan and fiberglass as possible, and I could probably get away with a R160, but definately wouldn't need to step up to the R200.

 

I see no reason for the weight to be over 1900, especially when you consider the motors are still gonna be lighter than the Z motor, even with two in the engine bay.

[Six_Shooter]

While I was looking at my 240Z (to be) on Saturday, the underhood sticker (still there ), said to test at 2780 lbs (27?? anyway) for emmisions load testing, I would assume that would be with two average weight occupants, at 180lbs each, that would be closer to 2500 lbs curb weight, and EVERY bit of information also suggests this for the early S30, the later versions the 260, and 280 getting upwards of 2800 lbs. Absolutly stripped down I could see leass than 2000 lbs, as many tube frame race cars can get this light, but even then, that's pretty light. Most tube frame roadster nastalgiac cars seem to be about 1800 lbs, that's no glass, firbreglass bodies, etc.

[Gollum]

Tube80Z's tube framed car is at 1620 with a 5.0 V8 and a T5.

 

 

That 2780 on your car you looked at was a 73' that's heavier than an earlier 240Z to begin with. And that's not just two passangers. That's also with cargo.

 

I was just looking it up, and it looks like the conservative curb weight for an early 240Z would be around 2350. Still no way it's even close to 2500 though. Your weights about the 260Z and 280Z are accurate though. Those cars are ungodly heavy for being the same profile as a 240Z.

 

EDIT:

 

Heres some links.

 

These are the most official specs i've seen on the 240Z on the net.

http://www.zshop.net.au/240tech.htm

 

Here's some weights of Zs as they were tested back in the day by magazines. Large variations as one should expect.

http://zhome.com/History/zcarperf.html

[strangethursday]

Another thing in regaurds to "no torque" is aren't we still talkin about PAIRED bike motors? Given that say the motor used has about 80ft/lbs stock. Paired 160ft/lbs. I'm not sure how much drivetrain loss there would be but lets say 25%. That brings torque at the wheels down to about 120ft/lbs. Don't sound too bad so far to me. What's a stock L24s wheel torque about? Granted the powerband will be up there but I'm not so sure that this car need to be streetable. On the other hand, you have guys like me that don't necissarily have a problem with leavin a stop light at high rpm haha

[Gollum]

Stock L series motors actually produce tons of torque, and will acheive very insane torque numbers when turbocharged.

 

The L series HP ratings were all over the place from 135hp to 170hp (i think, so don't quote me, but those should be close). But in all the ratings the torque was either CLOSE or over the HP rating. Usually within 95% of the HP rating.

 

If you look at the L28ET dynos you'll see that even stock they're producing a healthy 190+ torque.

 

But the reality is that many of the bike dynos I've been looking at, of the larger displacement superbikes like R1s busas etc, all make a healthy 100 or so torque, so combined they'd be near 200 which would be plenty streetable.

[m4xwellmurd3r]

i saw a dynochart for a stock 78 280z. it reached peak torque at around 2000 RPM (basically right off idle) and never dropped till around 5k, and it wasn't a hard drop either. it stayed around 134lbs of torque the entire time, with a peak hp of about 139 or something like that (googled a bit and found this site)

 

http://www.geocities.com/~z-car/specs/

 

apparently they should make 149hp at 5600rpm (makes sense, the plate says 170hp under the hood) and should make about 160ftlbs of torque at 4400rpm (and the torque curve is pretty flat starting off idle)

 

I also found this

http://www.datsuns.com/Tech/engines/dyno-l28-stock.gif

from the looks of it that dyno must be on an old engine.

 

So i think the L28 makes up for it's lower power by having a flat torque curve that doesn't drop harshly, right?

 

anyways, even for a bike engine, i think it could work. It'll be gearing hell to find the right combination to make the bike actually be able to make use of the power it has though.

[strangethursday]

anyways, even for a bike engine, i think it could work. It'll be gearing hell to find the right combination to make the bike actually be able to make use of the power it has though.

rear ratio is the 6s with a 7 speed? Haha

[m4xwellmurd3r]

Or somehow modify a 4x4 transmission to only run the low range gear setting?

Somehow it'll have to run some sort of reduction box between the transmission and rear diff to make the rpm range useable.

[BRAAP]

Six Shooter hit some very goods point in his last post regarding the Torque vs HP and how it comes to be, so a lot of what I'm saying here is just restating what he said.

When comparing a similar HP bike engine to a car engine, yes the bike engine will be working harder in that car vs how hard it worked in the bike, (10 second bike vs a 15 second car with similar HP, so be sure the engines cooling system and lubrication system, is up to the task of working just as hard, for longer stints...). The bike engine when used in car would be lugging around a lot more weight now, but the cars performance shouldn’t suffer if the cars engine that the bike engine replaces produces similar HP and both are optimally geared, (keys words, optimally geared). Deeper over all gearing will be used with a bike engine to take advantage of the bikes RPM and deliver similar torque at the wheels, (the cars acceleration). Point being that comparing the HP and torque figures of high revving bike engine vs low revving car engine are relative, not as offset as the numbers themselves make it appear.

 

 

For example, if the bike engine produces 200 HP @ 12,000 RPM and 100 ft lbs of torque @ 6000 RPM, it is the 200 HP you’ll be making use of, the gearing in the transmission/rear-end will take care of “torque at the wheels”.

A transmission is merely a Torque multiplier/RPM divider, as well as the diff.

Lets use an arbitrary L-6 for example, that produces 200 HP @ 6000 RPM and 200 ft lbs @ 3000 RPM compared to an arbitrary 200 HP @ 12,000 RPM, and 100 ft/lbs @ 6000 RPM bike engine. (these are general figures for the purpose of showing the relationship in how they accelerate an equivalent weight car and in are in no way ideal or what you will find in the real world, but the point still stands. There may be other forces at work such as drive train losses etc that will affect each a little differently, but those are beyond the scope of the point being made here.).

 

If both of these engines were in identical cars and those cars weighed identical, they would post similar ¼ mile ET and MPH, i.e. accelerate similarly from a dead stop, even though the bike engine is down on torque, it is making up for the lack of torque with RPM.

 

Lets break it down a little more. Both cars using identical 4 speeds transmissions, but the bike engine car is using a diff ratio of 7.08, the L-6 powered car is using diff ratio of 3.54, (half the ratio of the diff in the bike powered car). The Bike engine produces half the torque of the L-6, but spins twice as fast, so its diff ratio is twice as deep. (Keep I mind, this scenario is general just to set the idea and concept that a bikes lack of torque does not equate to lack of available acceleration when the gearing is optimized to take advantage of the bikes higher revving). In this scenario, both cars are shifting at the same vehicle speed, the tires are seeing the same torque at the ground as well as the same HP, (just as Six-Shooter eluded to, the tires are spinning at the same rate, yet the deeper diff ratio of the bike powered Z is effectively doubling the torque that passes through it to the tires vs the L-6 diff, i.e. torque multiplication through gearing. That is why 1st gear in our cars feels so darn quick when accelerating vs 4th gear. Torque multiplication).

 

In summation, generally speaking, the relationship between HP and Torque is important and is not to be discounted, though keep in mind the ft/lbs maybe less peak, the RPMs are grater, thereby compensating/making up for that lack of ft/lbs. Just because a bike engine produces similar HP to a car engine, yet only half as much Torque, that does not mean when installed in a car that it wont pull/accelerate just as hard. The Bike engine revs more, so the gearing will be deeper, therefore delivering similar Torque to the wheels and accelerate the car similarly.

[Gollum]

Thank you braap. I believe I've understood that all before, but you put it ever eloquently.

 

And with all that in mind, like I said, I care about HP and the HP curve. Torque is almost meaningless to me. With THAT being said, honda motors have nasty HP curves that make me sick (unless they're force induced). They lack any top end round off and just climb to peak and stop, making it so that you seem to always have a power sag when you change gears, whereas a good strong V8 has a broad enough HP curve that when you change gears it's still pulling strong.

 

 

Maybe I should search some bike forums and see if I can get the gearing for some of these transmissions, to see what RPM range they would actually be using when in a racing scenario. Yea, that sounds like a good idea. I'll do that.