How to get the power grounded to the ground.....
12-04-15, 03:59 PM
#1
How to get the power grounded to the ground.....
Sorry for the bad title, but that commercial cracks me up... 'grounded to the ground'
Little background.. I've had a few cars that I deemed as somewhat fast.. Eagle Talon, Tsi AWD, BMW E46 M3, G37S coupe and a couple of other similar level cars. All were under 350hp at the crank. I've come to realize why the average 'performance car' stayed in this range prior to the popularization of AWD and especially traction control. These cars are very 'spirited' but they are tame compared to a single rx7.
I always loved FD since they were new in my college days and finally bought one 6 or 7 years ago. The car was great to drive in stock form.
Over the last few years I did a complete engine rebuild, converted to a single Precision 6266 ball bearing, big intercooler, 3.5 inch down pipe, big injectors etc etc.
Anyways, with the car tuned at 18 pounds of boost, it can be brutally powerful (by my standards). Floor it in second gear on an on ramp and when the boost hits the tires spin on command. I have new Michelin Pilot Super Sport 285's in the back and 245's in the front. It can be somewhat better when the tires get good and hot, but its still unpredictable.
Right now the car demands 100% attention when you go full throttle.
Any ideas on how hook the power up to the ground more consistently?
BTW, you 3 rotor turbo guys are out of your minds. How do you begin to get that power to the ground.......
Little background.. I've had a few cars that I deemed as somewhat fast.. Eagle Talon, Tsi AWD, BMW E46 M3, G37S coupe and a couple of other similar level cars. All were under 350hp at the crank. I've come to realize why the average 'performance car' stayed in this range prior to the popularization of AWD and especially traction control. These cars are very 'spirited' but they are tame compared to a single rx7.
I always loved FD since they were new in my college days and finally bought one 6 or 7 years ago. The car was great to drive in stock form.
Over the last few years I did a complete engine rebuild, converted to a single Precision 6266 ball bearing, big intercooler, 3.5 inch down pipe, big injectors etc etc.
Anyways, with the car tuned at 18 pounds of boost, it can be brutally powerful (by my standards). Floor it in second gear on an on ramp and when the boost hits the tires spin on command. I have new Michelin Pilot Super Sport 285's in the back and 245's in the front. It can be somewhat better when the tires get good and hot, but its still unpredictable.
Right now the car demands 100% attention when you go full throttle.
Any ideas on how hook the power up to the ground more consistently?
BTW, you 3 rotor turbo guys are out of your minds. How do you begin to get that power to the ground.......
12-04-15, 04:24 PM
#2
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inb4 monsterbox...
How big are your wheels? A smaller wheel and larger sidewall tire in the back will help a LOT with forward traction. Also, you can let some air out of the back tires. These things will help the tire flex more around the wheel as the torque is applied.
Also, how stiff are your back springs?
How big are your wheels? A smaller wheel and larger sidewall tire in the back will help a LOT with forward traction. Also, you can let some air out of the back tires. These things will help the tire flex more around the wheel as the torque is applied.
Also, how stiff are your back springs?
12-04-15, 05:05 PM
#4
My experience is almost 15 years driving a 380rwhp/300rwtq 2,500lb FC and then some time in the same car with different turbo at 420rwhp/420rwtq.
Anything you can do to improve the low rpm torque and make the turbo spool faster will make the car much easier to drive.
Sounds counter intuitive, but here is why it works.
Lower torque than horsepower means your car makes its torque in the upper rpms.
On my old turbo I went from 200ftlbs@3,000rpm to 300ftlbs@3,500rpm (typical responsive single turbo set up). 200ftlbs at throttle tip in isn't enough to spin the tires so you floor it, then 500rpm later you are making 300ftlbs spinning so you have to let off the gas a tiny bit.
You don't want to let off the gas too much because then your boost drops out and you have to spool the turbo up again. So you keep it spooled and spinning tires a moderate amount and saw away at the steering wheel to keep it going straight.
I got pretty good at the timing of hearing the WG crack and backpedaling. I got pretty good at sawing away at the steering wheel to go straight.
Now on the new turbo I went from 300ftlbs@3,000rpm to 375ftbs@3,500rpm. Not only is that a 25ftlbs less jump in torque over the same 500rpm, but since it started at 300ftlbs at tip in, I never floored the gas pedal to start with since it started to spin tires as soon as I got on the gas at 3,000rpm.
Yes, the car would spin street tires on a 4th gear roll on, but only at full throttle. You get used to not always flooring it instead of having to get used to flooring it and letting up just the right amount at just the right time.
The turbo was more responsive and had more torque at tip in so you were never afraid to let off the gas and get back on it. Torque would be there.
I could completely bog a launch down to 1,000rpm with drag radials and would just stay on the gas and it would just run a low 12 instead of a high 11sec 1/4 mile.
I could shift anywhere from 6,000rpm to 8,000rpm in each gear and still run a high 11sec 1/4 mile.
Anything (ports, turbo, another rotor) you can do to increase torque at the same hp level will make the car easier to drive since torque doesn't come on all at once and its always there when you want it.
--------
If you can't change your turbo set-up I will say-
after 15 years and a couple near death experiences you do get better at putting the power down. Auto-x racing (mainly 1st and 2nd gear) really helped me learn the throttle control as well (and safely).
Anything you can do to improve the low rpm torque and make the turbo spool faster will make the car much easier to drive.
Sounds counter intuitive, but here is why it works.
Lower torque than horsepower means your car makes its torque in the upper rpms.
On my old turbo I went from 200ftlbs@3,000rpm to 300ftlbs@3,500rpm (typical responsive single turbo set up). 200ftlbs at throttle tip in isn't enough to spin the tires so you floor it, then 500rpm later you are making 300ftlbs spinning so you have to let off the gas a tiny bit.
You don't want to let off the gas too much because then your boost drops out and you have to spool the turbo up again. So you keep it spooled and spinning tires a moderate amount and saw away at the steering wheel to keep it going straight.
I got pretty good at the timing of hearing the WG crack and backpedaling. I got pretty good at sawing away at the steering wheel to go straight.
Now on the new turbo I went from 300ftlbs@3,000rpm to 375ftbs@3,500rpm. Not only is that a 25ftlbs less jump in torque over the same 500rpm, but since it started at 300ftlbs at tip in, I never floored the gas pedal to start with since it started to spin tires as soon as I got on the gas at 3,000rpm.
Yes, the car would spin street tires on a 4th gear roll on, but only at full throttle. You get used to not always flooring it instead of having to get used to flooring it and letting up just the right amount at just the right time.
The turbo was more responsive and had more torque at tip in so you were never afraid to let off the gas and get back on it. Torque would be there.
I could completely bog a launch down to 1,000rpm with drag radials and would just stay on the gas and it would just run a low 12 instead of a high 11sec 1/4 mile.
I could shift anywhere from 6,000rpm to 8,000rpm in each gear and still run a high 11sec 1/4 mile.
Anything (ports, turbo, another rotor) you can do to increase torque at the same hp level will make the car easier to drive since torque doesn't come on all at once and its always there when you want it.
--------
If you can't change your turbo set-up I will say-
after 15 years and a couple near death experiences you do get better at putting the power down. Auto-x racing (mainly 1st and 2nd gear) really helped me learn the throttle control as well (and safely).
12-04-15, 08:59 PM
#6
Thanks for the suggestions guys. I'm going to start with stiffening up the rear suspension.
I'll think about what I can do for that lower end torque as well. What you described is exactly how my car behaves. Power and or torque just pours on around 4k rpm. Its what I expected, but now that I have it.. just trying to see if I can manage it to some level.
As for that solid axl - maybe if you had painted it red.
I'll think about what I can do for that lower end torque as well. What you described is exactly how my car behaves. Power and or torque just pours on around 4k rpm. Its what I expected, but now that I have it.. just trying to see if I can manage it to some level.
As for that solid axl - maybe if you had painted it red.
12-04-15, 09:04 PM
#7
Blue, what's your new turbo setup and do you have a port job? That torque sounds impressive indeed.
I kept the stock ports in my FD for a more reliable idle. I can imagine I could improve marginally on the precision turbo with another, but I wouldn't expect that much more torque.
I kept the stock ports in my FD for a more reliable idle. I can imagine I could improve marginally on the precision turbo with another, but I wouldn't expect that much more torque.
My experience is almost 15 years driving a 380rwhp/300rwtq 2,500lb FC and then some time in the same car with different turbo at 420rwhp/420rwtq.
Anything you can do to improve the low rpm torque and make the turbo spool faster will make the car much easier to drive.
Sounds counter intuitive, but here is why it works.
Lower torque than horsepower means your car makes its torque in the upper rpms.
On my old turbo I went from 200ftlbs@3,000rpm to 300ftlbs@3,500rpm (typical responsive single turbo set up). 200ftlbs at throttle tip in isn't enough to spin the tires so you floor it, then 500rpm later you are making 300ftlbs spinning so you have to let off the gas a tiny bit.
You don't want to let off the gas too much because then your boost drops out and you have to spool the turbo up again. So you keep it spooled and spinning tires a moderate amount and saw away at the steering wheel to keep it going straight.
I got pretty good at the timing of hearing the WG crack and backpedaling. I got pretty good at sawing away at the steering wheel to go straight.
Now on the new turbo I went from 300ftlbs@3,000rpm to 375ftbs@3,500rpm. Not only is that a 25ftlbs less jump in torque over the same 500rpm, but since it started at 300ftlbs at tip in, I never floored the gas pedal to start with since it started to spin tires as soon as I got on the gas at 3,000rpm.
Yes, the car would spin street tires on a 4th gear roll on, but only at full throttle. You get used to not always flooring it instead of having to get used to flooring it and letting up just the right amount at just the right time.
The turbo was more responsive and had more torque at tip in so you were never afraid to let off the gas and get back on it. Torque would be there.
I could completely bog a launch down to 1,000rpm with drag radials and would just stay on the gas and it would just run a low 12 instead of a high 11sec 1/4 mile.
I could shift anywhere from 6,000rpm to 8,000rpm in each gear and still run a high 11sec 1/4 mile.
Anything (ports, turbo, another rotor) you can do to increase torque at the same hp level will make the car easier to drive since torque doesn't come on all at once and its always there when you want it.
--------
If you can't change your turbo set-up I will say-
after 15 years and a couple near death experiences you do get better at putting the power down. Auto-x racing (mainly 1st and 2nd gear) really helped me learn the throttle control as well (and safely).
Anything you can do to improve the low rpm torque and make the turbo spool faster will make the car much easier to drive.
Sounds counter intuitive, but here is why it works.
Lower torque than horsepower means your car makes its torque in the upper rpms.
On my old turbo I went from 200ftlbs@3,000rpm to 300ftlbs@3,500rpm (typical responsive single turbo set up). 200ftlbs at throttle tip in isn't enough to spin the tires so you floor it, then 500rpm later you are making 300ftlbs spinning so you have to let off the gas a tiny bit.
You don't want to let off the gas too much because then your boost drops out and you have to spool the turbo up again. So you keep it spooled and spinning tires a moderate amount and saw away at the steering wheel to keep it going straight.
I got pretty good at the timing of hearing the WG crack and backpedaling. I got pretty good at sawing away at the steering wheel to go straight.
Now on the new turbo I went from 300ftlbs@3,000rpm to 375ftbs@3,500rpm. Not only is that a 25ftlbs less jump in torque over the same 500rpm, but since it started at 300ftlbs at tip in, I never floored the gas pedal to start with since it started to spin tires as soon as I got on the gas at 3,000rpm.
Yes, the car would spin street tires on a 4th gear roll on, but only at full throttle. You get used to not always flooring it instead of having to get used to flooring it and letting up just the right amount at just the right time.
The turbo was more responsive and had more torque at tip in so you were never afraid to let off the gas and get back on it. Torque would be there.
I could completely bog a launch down to 1,000rpm with drag radials and would just stay on the gas and it would just run a low 12 instead of a high 11sec 1/4 mile.
I could shift anywhere from 6,000rpm to 8,000rpm in each gear and still run a high 11sec 1/4 mile.
Anything (ports, turbo, another rotor) you can do to increase torque at the same hp level will make the car easier to drive since torque doesn't come on all at once and its always there when you want it.
--------
If you can't change your turbo set-up I will say-
after 15 years and a couple near death experiences you do get better at putting the power down. Auto-x racing (mainly 1st and 2nd gear) really helped me learn the throttle control as well (and safely).
Trending Topics
12-04-15, 10:25 PM
#8
I went from a maxed out 57mm turbo (60-1) to a maxed out 57mm turbo (EFR 7670).
The dyno is what I raced with 26psi and then it ran out of compressor and faded to 21psi by redline.
The 1st port job I did way back was big, with early opening and late closing on intake and exhaust. The car was really hard to drive as it had NOTHING down low and then above 5,000rpm it all came on at once. Didn't matter if you fed in 20% throttle or full throttle it responded with full torque above 5,000rpm.
Now my port is early opening as possible intake with stock closing line and as little taken out of the ports as possible (low volume/high velocity) and just a reshaped exhaust with slightly earlier opening (D shape port with flat on top).
12-04-15, 10:35 PM
#9
Thanks for the suggestions guys. I'm going to start with stiffening up the rear suspension.
I'll think about what I can do for that lower end torque as well. What you described is exactly how my car behaves. Power and or torque just pours on around 4k rpm. Its what I expected, but now that I have it.. just trying to see if I can manage it to some level.
As for that solid axl - maybe if you had painted it red.
I'll think about what I can do for that lower end torque as well. What you described is exactly how my car behaves. Power and or torque just pours on around 4k rpm. Its what I expected, but now that I have it.. just trying to see if I can manage it to some level.
As for that solid axl - maybe if you had painted it red.
You want more traction and you are going to stiffen the rear end??????
softer springs in the rear the better.
Low end torque, long cold air intake with velocity stack on the end of it.
Short direct intercooler piping.
those are good to start.
12-04-15, 10:42 PM
#10
HPP 2 in 1 diff cradle with 295/35 BFG drag radials with gear based boost control is working very well for me. The BFG drag radials are not made anymore
14psi in first, 18psi in 2nd and over 660whp and 550whtq at 32psi 3rd gear and up. Holds every gear no problem with no drama what so ever. Just goes where ever I point it really really fast
I have tried high dollar pure street tires and they just will not hold. Around the 500whp mark seems to be the end of any traction what so ever on even the best street tire.
14psi in first, 18psi in 2nd and over 660whp and 550whtq at 32psi 3rd gear and up. Holds every gear no problem with no drama what so ever. Just goes where ever I point it really really fast
I have tried high dollar pure street tires and they just will not hold. Around the 500whp mark seems to be the end of any traction what so ever on even the best street tire.
12-05-15, 04:42 PM
#12
camajo Point taken. I misinterpreted the prior reply. Soft must allow for more rear weight transfer to help it bite?
Kinda, sometimes, depends.
In straight line acceleration soft springs will allow the rear to squat for more weight transfer to the rear. That is *generally* a good thing, except when its not- see below.
The soft spring rear squat in an FD will give you a bunch of negative camber (because these cars were built to corner), so that will decrease rear traction (especially if you have really flat tread low profile tires). That is a bad thing.
Also, if the spring is soft and the shock damping is not good enough the rear will squat so hard it hits the bumpstops on the shocks which are harder than any spring. This might end up working just fine on the drag strip, but if the road is bumpy or uneven traction will suffer.
You want the right compromise.
Too stiff rear springs/shocks definitely stop rear weight transfer and make rear traction worse.
When you add in accelerating off a corner you get more variables as well.
For maximum straight line rear traction I would say stock springs with upgraded adjustable shocks is a good place to start or if you can find the old HKS drag coilovers.
For straight line traction tall narrow tires at low pressure are best. This gives you a long contact patch.
Just about everything you do for more straight line traction will make your car suck at cornering traction so you have to compromise.
Also, how does the car behave after it loses traction (ie, how easy is it to regain traction/control). A soft rear and drag radials aired down is great for traction but also much easier to wreck with.
Kinda, sometimes, depends.
In straight line acceleration soft springs will allow the rear to squat for more weight transfer to the rear. That is *generally* a good thing, except when its not- see below.
The soft spring rear squat in an FD will give you a bunch of negative camber (because these cars were built to corner), so that will decrease rear traction (especially if you have really flat tread low profile tires). That is a bad thing.
Also, if the spring is soft and the shock damping is not good enough the rear will squat so hard it hits the bumpstops on the shocks which are harder than any spring. This might end up working just fine on the drag strip, but if the road is bumpy or uneven traction will suffer.
You want the right compromise.
Too stiff rear springs/shocks definitely stop rear weight transfer and make rear traction worse.
When you add in accelerating off a corner you get more variables as well.
For maximum straight line rear traction I would say stock springs with upgraded adjustable shocks is a good place to start or if you can find the old HKS drag coilovers.
For straight line traction tall narrow tires at low pressure are best. This gives you a long contact patch.
Just about everything you do for more straight line traction will make your car suck at cornering traction so you have to compromise.
Also, how does the car behave after it loses traction (ie, how easy is it to regain traction/control). A soft rear and drag radials aired down is great for traction but also much easier to wreck with.
12-05-15, 10:09 PM
#15
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The problem with the RX-7 is it light weight so has less tire friction than a heavier car.
We need a futuristic device that increases gravity but not mass.
Or keeps gravity constant but reduces mass.
Some type of Higgs boson control device.
We need a futuristic device that increases gravity but not mass.
Or keeps gravity constant but reduces mass.
Some type of Higgs boson control device.
12-15-15, 05:53 PM
#18
BLUE TII knows what's up!
R-compound tires are your best friend as well!
20b and 13b over 500hp would spin my tires with a slight leftward kick and always was always a near suicide job. Swapping to R-compounds was UNBELIEVABLE. ZERO spinning in 2nd and 3rd after tires are warm, on mere 255's with 600+rwhp. If it did spin, it would also track straight, which saves the heart rate!
I don't know all the physics and theories but for what is worth my setup was:
-koni yellows (8 years old half blown out) on tein drop springs, softest setting in rear for the squat
-17x9 in the back, 17x8.5 up front, 235/255 Maxxis RC-1
R-compound tires are your best friend as well!
20b and 13b over 500hp would spin my tires with a slight leftward kick and always was always a near suicide job. Swapping to R-compounds was UNBELIEVABLE. ZERO spinning in 2nd and 3rd after tires are warm, on mere 255's with 600+rwhp. If it did spin, it would also track straight, which saves the heart rate!
I don't know all the physics and theories but for what is worth my setup was:
-koni yellows (8 years old half blown out) on tein drop springs, softest setting in rear for the squat
-17x9 in the back, 17x8.5 up front, 235/255 Maxxis RC-1
Last edited by Monsterbox; 12-15-15 at 05:55 PM.
12-15-15, 05:57 PM
#19
HPP 2 in 1 diff cradle with 295/35 BFG drag radials with gear based boost control is working very well for me. The BFG drag radials are not made anymore
14psi in first, 18psi in 2nd and over 660whp and 550whtq at 32psi 3rd gear and up. Holds every gear no problem with no drama what so ever. Just goes where ever I point it really really fast
I have tried high dollar pure street tires and they just will not hold. Around the 500whp mark seems to be the end of any traction what so ever on even the best street tire.
14psi in first, 18psi in 2nd and over 660whp and 550whtq at 32psi 3rd gear and up. Holds every gear no problem with no drama what so ever. Just goes where ever I point it really really fast
I have tried high dollar pure street tires and they just will not hold. Around the 500whp mark seems to be the end of any traction what so ever on even the best street tire.
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