Hypergear Turbochargers and High flow Services Development thread

[MrStabby]

Change in torque produces wheel spin... Not peak torque

I'm with rolls on this one - why would change in torque produce wheelspin? Think about how torque becomes force at the road surface.

[GTScotT]

I'm with rolls on this one - why would change in torque produce wheelspin? Think about how torque becomes force at the road surface.

Because its not linear. A sharp rise in torque will cause wheelspin.

I race RC, when you flip the RC car mid corner on a swept furface the reason was a loss of and then re gain of traction. Similar principal.

[Harey]

100% agree on the change in torque causing wheelspin.

You can have a huge peak torque figure but if the torque builds gradually you have a good chance of no wheelspin. If there is no torque then a sudden 500Nm jump over 500rpm it will be very hard to not get a lot of wheelspin.

Normally in a turbocharged car the biggest change in torque will also be as the turbo hits boost and reaches its peak torque, but that is just a coincidence.

See below example, yes it would be the strangest dyno curve ever but you get the idea.

[Harey]

That would be from boost controller, I found this boost creep and drop behavior happens to customers with return flow coolers. check hary's result pre and after cooler tests:

http://www.skylinesaustralia.com/forums/topic/261613-hypergear-hiflow-service-continued/page__st__1640__p__5772487#entry5772487

Been doing more research on this and it seems there are plenty of guys running return flow intercoolers making a lot more power:

http://www.skylinesaustralia.com/forums/topic/359972-most-power-with-a-return-flow-intercooler-and-std-piping/page__p__5747667__fromsearch__1#entry5747667

[Rolls]

Change in torque produces wheel spin... Not peak torque

Can someone give a scientific reason why this is so? I'm not convinced.

There is a limit of grip the tyre can provide, the only force acting on the tyre is the torque turning it, I don't see why a fast increase in torque would cause this?

I can see why fastly increasing torque might be conducive to wheel spin, but it in itself won't cause it. Eg you break traction with x torque, the wheel spins increasing rpm which also increases torque hence it spins faster. If you have flat torque it will not continue to spin like this, however if the torque value is enough to cause the wheel spin in the first place it will still cotinue to spin, it just won't smash the limiter like a steep torque curve would..

If the torque curve is dropping off and x torque causes it to spin, the increase in rpm would cause the torque to drop and hence stop the tyre spinning, but if it doesn't drop below the value required to spin it in the first place, it will continue to spin.

edit: That was confusing to write lol.

Edited July 19, 2011 by Rolls

[GTScotT]

Can someone give a scientific reason why this is so? I'm not convinced either way now, going to have to think about it some more.

Without going into the physics of it, as I CBF to look up the formulas.

Torque is force, traction is force. The 1400kg car car only accelerate at a certain rate FROM a certain speed with its given variables (tyres suspension etc etc etc).

At a given point the rotating effort from the tyres (torque) will overcome the traction to the road. A sharp rise while it is already spinning will cause it to try and accelerate faster and with the additonal force it will overcome the available traction.

Think of traction as KG per square CM from tyre to road, how much force to you need to break the traction? Like the handbrake, yeah it will hold the car from rolling away, but the motor can overcome the force on the little handbrake shoes if you try hard enough cant it? Is it the increase in engine RPM that will make you break free of the handbrakes hold or is it more specifically the torque (ala FORCE) of the motor that will force the wheels to move?

Think about it dude...... Its physics.

[Rolls]

Think about it dude...... Its physics.

I did and it isn't correct, it is the actual torque value that causes wheel spin, not whether it is increasing or not. If it increases steeply it is more likely to maintain wheel spin and not a single chirp though which is what I think you are getting at.

read my edited post.

[GTScotT]

I did and it isn't correct, it is the actual torque value that causes wheel spin, not whether it is increasing or not. If it increases steeply it is more likely to maintain wheel spin and not a single chirp though which is what I think you are getting at.

read my edited post.

If you are accelerating at X rate with your torque building at Y rate then why would you not impact the variable of traction if your Y rate increase significantly from your X rate that it previously was?

Think about it logically. You can accelerate as fast as the force you apply vs the amount of traction you have, your traction is constant, a sharp rise in torque (AKA FORCE) is NOT constant and will require more traction that your not getting any more of.

[Rolls]

Traction, torque, force are all instaneous things, a sharp rate of torque increasing is something that happens over time.

A sharp increase in torque is more likely to sustain wheel spin, but if the torque figure during that sharp rise never exceeds what your wheels can put to the ground, it won't cause any spin.

[Harey]

Its probably a crude example but say a clutch drop as opposed to a good launch at the same rpm. The peak torque is the same, the only difference is how sudden the torque changes.

[Rolls]

Ok after some reading and thinking I agree, but not from the examples given haha. The stuff I read about was tyre deformation, eg if you spend 10 seconds applying a torque figure x that doesn't cause wheel spin, if you decrease the time from 10 and tend towards 0, there will always be a time factor that causes wheel spin, due to the tyre not having enough time to deform.

The clutch example is bad harey, a better one would be stabbing the throttle as theres no stored up energy and torque multiplcation from a slipping clutch.

Edited July 19, 2011 by Rolls

[Harey]

The clutch example is bad harey, a better one would be stabbing the throttle as theres no stored up energy and torque multiplcation from a slipping clutch.

yes but at least I am right

[Rolls]

yes but at least I am right

Your example is wrong.

anyway, enough off topic

[GTScotT]

Ok after some reading and thinking I agree, but not from the examples given haha. The stuff I read about was tyre deformation, eg if you spend 10 seconds applying a torque figure x that doesn't cause wheel spin, if you decrease the time from 10 and tend towards 0, there will always be a time factor that causes wheel spin, due to the tyre not having enough time to deform.

The clutch example is bad harey, a better one would be stabbing the throttle as theres no stored up energy and torque multiplcation from a slipping clutch.

You fool, how is this not direct related to what I was saying LOL. Tyres are a freaking VARIABLE.

The thing you are missing is, we are bastardising the concept by saying an 'increase in torque' will create wheel spin. The set variable is the acceleration, the 'increase' we are harping on about is actually the rate of GAIN for torque. IE how steep the curve is on gaining torque.

And hey this is what perfect turbo selection is about in my eyes. If you can have a steep curve from a low RPM to a usable RPM aslong as the width is good enough you should be able to get some big time acceleration.

If I turned back time to pre JZ for me, I would have kept my crappy RB and put one of these SS turbos on. Problem was I did not have the patience to wait for the development of a successful unit like HG have now.

IMHO there arent enough SS1 and SS2 powered skylines out there, and I think those turbos cater almost perfectly for the 250 and 300kw crowd from what we are seeing.

[rondofj]

Scott how do the JZs compare to the crappy RBs?? RB25 and up. Heaps more down low or not that much difference??

[wolverine]

RB's fits in the engine bay no mods.

I bet that is a win for the crappy RB.

[DVS JEZ]

i just bought an r32 gtst drifter, no engine etc etc, in the boot was an Air Research T04 with OP6 on the rear housing.

i Spoke to Stao this arvo about rebuilding it to remove the crazy amounts of shaftplay.

very curious to see what he can make of it for my RB25 i have for it.

[hypergear]

Some very constructive ideas. any way, refer to the GenEses development, The belt supercharger probably won't do as by looking at the dynosheet of SS-2 All I need is some thing makes 2psi+ pre 2500rpms, which should increase down low torque and extend mid range. I'm looking at a 35V electric motor:

http://www.rcgroups.com/forums/showthread.php?t=1276604

Run that into a 3inches duction fan I think I have a pretty good chance getting that to boost. I'm hopping it doesn't self destruct when turbo is sucking at 24psi, or I will need an additional intake pipe which opens when intake pipe pressure becomes negative. If I can program some sort of relay that activate this device in a short block of 5 secs at certain throttle position and have its battery(s) charged all times then it should be pretty consistent.

How ever if I do get 300rwkws with the new prototype with stock response then there might be no need for it. Either way its going to be a interesting hobby turbo to work on in the weekends.

Torque and wheel spin, if the torque is a built up in a 45 degrees angle then that will be lot less likely to wheel spin then some thing shoot up in a 75 degrees angle. As the driver I personally would like to feel my car's pulling all the way to red from the second I step into throttle. So far the SS-1, SS-2 and G3 FNT have felt great on road.

I did have a customer whom I recently built a FNT G3 for, he's made 265rwkws at 17psi on a super safe tune, even thou it didn't max lots of power but he's got a very linear curve and peaked heaps of linear torque at 4000RPMs, then that torque held very straight towards 7000rpms. I will post up his sheet this weekend, that sort of curve would feel excellent on road and beating V8 with.

[Birds]

Hmmm I have a couple of hypotheticals that may support Rolls' peak torque argument here. Will post tomorrow when I have time, but should we continue in this thread or another one? It's an interesting topic.

[Harey]

My vote is for new topic