Forcedfed Stage 1Turbo Kit Pricing

[BrettP]

Originally Posted by Greg

I'm afraid that's not going to help you much when you (try to) put 400hp to the ground, no?

'Greg

I am not worried about putting 400 horsepower to the ground as the car has no issues with 300 horsepower so far with an open diff.

[Greg]

Man, I gotta get me a ride...

'Greg

[Greg]

Originally Posted by espritGT3

The Quaife is only available with one final drive ratio. The remaining ratios were cut to spec, with a taller 1st gear and 6th shorter than the original 5th. However, with a 8:1 CR motor that makes 150 HP off boost and 3 times that at full boost, it would stall and be impossible on hills if first were too tall. Also it's not it's not very practical on the street to have to launch at 5000 rpm lighting the tires to avoid bogging. So the gearing is a compromise. The gears are semi-helical instead of straight cut as well, futher limiting ratio options. I think gear boost makes the most sense (absent traction control) and Lotus UK agrees, but I haven't been spending enough time in the US to cobble a system together and test it yet.

My point was there's only so much power you can put to the ground. A less powerful, but more tractible car can be quicker on real roads and more enjoyable to drive. Keep in mind that the Elise doesn't have that large of a contact patch. More is not necessarily always better.

I'm agreeing with you. However, all the gears in your transaxle are rebuildable, as well as the ring and pinion in the ATB differential. So, you CAN change the final drive ratio to suit your application. They build boxes for a lot different cars.

I'm not sure anyone will argue that your system isn't particularly fun to drive on the street. That's how it was designed though, or at least with this choice of part combinations that's what you ended up with.

It's also not fun to spend your money experimenting to get the right "streetable" kit. That's what we want to pay Brett for...

'Greg

[espritGT3]

Originally Posted by Greg

I'm agreeing with you. However, all the gears in your transaxle are rebuildable, as well as the ring and pinion in the ATB differential. So, you CAN change the final drive ratio to suit your application. They build boxes for a lot different cars.

I'm not sure anyone will argue that your system isn't particularly fun to drive on the street. That's how it was designed though, or at least with this choice of part combinations that's what you ended up with.

It's also not fun to spend your money experimenting to get the right "streetable" kit. That's what we want to pay Brett for...

'Greg

Greg
I'll send you a private response on the Quaife and gearing issues, but I don't think it's fair take up space here talking about my Esprit.

Back to the Elise. We've been talking about HP, but really the issue is torque to the wheels. And comparing the Toyota to the Esprit motor is like comparing apples and oranges as the Toyota revs much higher, putting out more HP for a given torque. And has variable valve timing to smooth out the torque curve.

For the street, it's torque that's more useful than peak horsepower. The present turbo is producing 170 ft-lbs. I'm guessing that 200-220 ft-lbs would probably be very nice and interesting for those that want more.

But 300 ft-lbs or more will probably cause traction problems. Gearing the car taller will yield a higher top speed at the cost of acceleration. So unless you drive your car places where you can go 175mph, there's not much point.

Gear ratios can be used to manipulate torque at the wheel, but traction, and therefore acceleration, is limited by the tires.

We'll see soon enough when Bret builds his 400 hp monster. Maybe he'll end up in that grey area between 220 and 300 ft-lbs where traction may or may not be a problem. I'm guessing 270-280 ft-lbs and will be curious to see how it hooks up.

Remember to watch the torque numbers.

[NtflBlueLiz]

Uninformed thoughts here about the Elise's light weight when adding more HP and torque:
One side of the equation
- Since its light it doesn't put as much weight on the wheels so as you upgrade the engine and have huge amounts of power a lot of it may go up in smoke as the tires loose grip and spin.
The flipside
- Since its light, there is relatively less mass ( than comparably powerfull cars) to be propelled forward by the additional power so it may need less rubber than other similarly powerfull cars to still be able to get good traction.
Anyone venture a guess as to which point is more valid?

I'm sure some engineer armed with some good equation ( vectors?), tire ratings, tire sizes, street surface friction rating and torque rating at the wheels can come up with some idea of how much rubber one may need for straight line accelaration without loosing traction. The number won't be any good for turns as you add more loads but it should give an idea, or you can just go out there and smoke tires untill you figure it out

[espritGT3]

[quote=NtflBlueLiz]Uninformed thoughts here about the Elise's light weight when adding more HP and torque:
One side of the equation
- Since its light it doesn't put as much weight on the wheels so as you upgrade the engine and have huge amounts of power a lot of it may go up in smoke as the tires loose grip and spin.
The flipside
- Since its light, there is relatively less mass ( than comparably powerfull cars) to be propelled forward by the additional power so it may need less rubber than other similarly powerfull cars to still be able to get good traction.
Anyone venture a guess as to which point is more valid?

Fred,

Your observations are spot on. Both conccepts are both valid. You're trying to balance grip which is a function of force (weight), contact patch and coefficent of friction vs inertia.

However, I'm not the right type of engineer to work the sums.

But look at a Formula Atlantic car for comparison. They weigh 1000 lbs, have 240 hp and make about 160 ft-lbs of torque. They're fitted with 14" wide rear rims and slicks. The Elise has 7.5" rear rims.

What does that tell you something about how much grip they need?

On balance they're geared short, to do about 140mph at 10,000 rpm for most road courses. But with 300 ft-lbs of torque an Elise is still going to need more rubber than its got, despite taller gearing.

[NtflBlueLiz]

espritGT3,

I dropped out of engineering after my first year ( 21 years ago ) so I definetely am not the one to do the calculation! but I see your point about the Formula Atlantic Cars.

[CiceroCicero]

I don't see why 400hp in an Elise should be a problem. That'll work out at about 450hp per tonne, which doesn't seem that excessive especially when compared to the McLaren's 600bhp/tonne and Koennigsegg CCR's 700bhp/tonne figures.

Hopefully adding a little extra downforce will help the car dig its heels in when it puts the power down.

What I'm intersted in is how the power will be delivered; I suspect, although I'd like to be proved wrong, that there'll be a lot of lag and then a large hit of power which will make for an interesting, if flawed, driving experience.

275bhp should prove more than enough for all but track use.

[espritGT3]

Originally Posted by CiceroCicero

I don't see why 400hp in an Elise should be a problem. That'll work out at about 450hp per tonne, which doesn't seem that excessive especially when compared to the McLaren's 600bhp/tonne and Koennigsegg CCR's 700bhp/tonne figures.

Hopefully adding a little extra downforce will help the car dig its heels in when it puts the power down.

What I'm intersted in is how the power will be delivered; I suspect, although I'd like to be proved wrong, that there'll be a lot of lag and then a large hit of power which will make for an interesting, if flawed, driving experience.

275bhp should prove more than enough for all but track use.

Metric or long tons I assume. The McLaren runs 12" wide rear rims and the Koennigsegg 13". Downforce will help at speed, but the problem is in 1st and 2nd gear when you don't have that much speed to create downforce.

There may not be that much lag, but the hit . . . I know that flawed driving experience all too well ...

[Randy Chase]

My 2 cents. The Elise is already a little under-tired. I can spin the tires in a second gear corner now just by hitting the cam switch over or applying full throttle on the cam. The more power you add, the more you will be feathering the trottle and at some point, the declining returns will mean you are not using much of that power, unless you can get a lot more tire under the car.

I think a nice sweet spot will be around 250hp...and maybe up to 300hp. Just my gut feel, but 250hp in this car will be nuts (or is nuts)..in a good way. But you have to be a lot more careful with power on oversteer. Maybe up to 300 and it will still be good, but will require a lot of skill to drive. At some point, most of the extra power is going to waste as it only be converted to tire smoke.

I will be interested in seeing how people get more tire under the car, as I might be going the 300hp...or more... route after we run the car stock for a year.

[bogie]

over here we have 250-310bhp (210-300lb/ft) Elises weighing 720-800Kg. The problem with traction is apparent over the 220-250bhp mark...especially with forced induction providing the torque you can light the std 225 rears up in 1st/2nd/3rd gear in the dry. If its remotely damp then 1st and 2nd gear you dont move anywhere...well thats my experience anyway !

My car is 220-230bhp ish with 195lb/ft and 810Kg fully laden .....it would be nice to have another 50bhp on tap up the rev range, but I think 200-250lblft off torque is more than enough for the rubber.

The Lotus Esthi has 400bhp + in sub 1000Kg...they used the Esprit 17/18" wheels on that...along with the brakes...it needed them ..........

[GabbaGabbaHey]

In the last Dec Evo Car of the Year review, they complained that the Vauxhaul VXR with I think w 220 hp was a bit of a handful and needed to use higher gears on turn exits to control torque.

The VXR IIRC has a LSS suspension and possibly it was a bit cold for the tires. In any event the Elise and Exige were favored although obviously the later has LSS too. Perhaps the VXR's torque curve is less road friendly than a Forcefed Toyota.

[NtflBlueLiz]

So bottom line is how can we get more tire under the Elise to make it worthwile getting more power. Can we run different offsets to get the tire further into the car rather than sticking out? We also need to do it front and back to keep the car balanced.
Do we also need different shocks and springs to compensate for the additional rotational mass of larger tires/wheels? or it doesn't matter?
I'm interested in doing the mod once it can be done here in Florida, this would be the first time I ever mod any vehicle in my life, sounds exciting!

[aletes]

Originally Posted by Randy Chase

I think a nice sweet spot will be around 250hp...and maybe up to 300hp. Just my gut feel, but 250hp in this car will be nuts (or is nuts)..in a good way. But you have to be a lot more careful with power on oversteer. Maybe up to 300 and it will still be good, but will require a lot of skill to drive. At some point, most of the extra power is going to waste as it only be converted to tire smoke.

Wow, I think you pegged the numbers. In order to maintain the handling characteristics of the Elise, the horsepower needs to be under 300 ... preferably closer to 250. It really depends on how much power is delivered under the curve.

[ChrisB]

Originally Posted by NtflBlueLiz

Do we also need different shocks and springs to compensate for the additional rotational mass of larger tires/wheels? or it doesn't matter?

The rotational mass, per se, doesn't matter, but the fact that it is unsprung weight does. Changing the offset will also affect the leverage of the unsprung weight, which will affect both the springs and shocks. Changing the offset will also affect the suspension geometry.

[moomin]

Forcedfed, any news on a UK installer?

[BrettP]

Originally Posted by moomin

Forcedfed, any news on a UK installer?

We are working on it this week and I hope to announce a UK dealer very shortly.

[Ruediger]

Originally Posted by bogie

over here we have 250-310bhp (210-300lb/ft) Elises weighing 720-800Kg. The problem with traction is apparent over the 220-250bhp mark...especially with forced induction providing the torque you can light the std 225 rears up in 1st/2nd/3rd gear in the dry. If its remotely damp then 1st and 2nd gear you dont move anywhere...well thats my experience anyway !

My car is 220-230bhp ish with 195lb/ft and 810Kg fully laden .....it would be nice to have another 50bhp on tap up the rev range, but I think 200-250lblft off torque is more than enough for the rubber.

The Lotus Esthi has 400bhp + in sub 1000Kg...they used the Esprit 17/18" wheels on that...along with the brakes...it needed them ..........

Why not use an ECU which has a TRACTION CONTROL- feature e.g. the DTA - P8PRO?
( http://www.dtafast.co.uk )
This should even solve the 400 WHP problem for a 750 kg Elise.



>>>The traction control system, will limit the amount of driven wheel spin to any desired slip compared with the un-driven wheels. 2 complete sets of parameters are available to allow for differing conditions. These are controlled by a switch on the dash of the car. If no switch is used then the dry settings are used. Besides the wet/dry switch an on/off switch must be fitted on the dash.


MINIMUM SPEED TO ACTIVATE

Below this un-driven wheel speed the vehicle is considered to be stopped and the traction control will take no action: Below the selected minimum RPM the traction control will take no action. Setting depends on engine performance and the desired car dynamics.

MINIMUM THROTTLE TO ACTIVATE

Below this throttle position the traction control system will take no action.


TARGET SLIP PERCENTAGE

The system constantly calculates the difference in wheel speed between driven and un-driven wheels. Some slip is beneficial to maximum acceleration, say about 20%. Start line situations are different and require the use of Launch Control. If launch control is active then the traction control will take no action until this has relinquished control over the system.

BALANCE TO FASTER DRIVEN WHEEL

This setting is used to allow some speed averaging across the two driven wheels. For instance in the case of a free differential it should be set to nearly 100%. In a car with a very stiff limited slip differential it should be set to say 25%.

DELAY AFTER START

After the system detects that a car has stated to move it waits this length of time before engaging traction control (unless launch is active see above). There is also a delay before the system considers a car is stopped. This is to allow for the locked brake situation. See General Traction Settings.

EXCESS SLIP TO HARD CUT

This effectively decides how aggressive the cylinder cutting is when slip is detected. If it is too aggressive the car is unstable. Only testing can determine at what level this should be set.
Etc, etc------<<<

[espritGT3]

[quote=Ruediger]Why not use an ECU which has a TRACTION CONTROL- feature e.g. the DTA - P8PRO?
( http://www.dtafast.co.uk )
This should even solve the 400 WHP problem for a 750 kg Elise.

I thought the reason people bought Elises was to get away from all of the artificial drivers' aids. Somehow, using ASR doesn't seem right.

I also don't know how well such systems work on turbocharged cars.

[Stan]

If you want to add traction control to a car the most sophisticated one is from Race Logic. It data logs and has about FIFTY (50) things you can set or adjust. Launch control (wet or dry), full throttle shifts, knob adjustable slip %, etc, etc. I have it in my M3 and it works great. It is very different than OE traction control as it is made for sport purposes and can speed you up rather than granny-proof the car.