I’ve always wanted a car that can cruise around the streets at low rpm, and then accelerate instantly when foot is planted, without having to change down a gear or wait for the turbo to spool. However I still want the handling of an Evo, and the power gains available from a turbo. Now many people say I should just get a V8, but I want something that handles well, and a V8/V10/V12 that handles as well as an Evo does is just outside of my budget.

As such a friend and I have come up with a design to modify an Evo to do this; performance modelling indicates the following torque curve can be achieved. At this stage I’m not after a technical appraisal; rather I’m interested to know what people think of this curve, especially in terms of how it would feel to drive as a daily driver? Would it be worth the time, effort and money to achieve this?!?



I wasn’t going to get into the technical details, but I can see that no-one is going to believe me if I don’t explain :-) I thought of adding a supercharger as a twin-charge setup, but even that would struggle to get that sort of torque down low – I realize it’s pretty much impossible to get that from a 2L engine by itself. That’s why I’ve added an electric motor to complement the turbo – elec gives heaps of instant torque at low rpm, and then the turbo takes over at high rpm. (I’ve designed and built a number of electric vehicle powertrains before, that’s actually my specialty.)

 

hahahahahahhahahaha.....not gonna happen guy

 

This is just my gut feeling so anyone can correct me if I'm wrong, but a torque curve like that would do what you want but not in turbo car, unless you had a ridiculously small turbo. You would put your foot down but you would have to wait for the turbo to spool before you could achieve that level of torque. So probably not worth it in an evo.

I feel you would be better off going with a high compression NA (a supercharger might be effective but I don't know much about them).

 

Hmmm, well that sure does look like it would be a sweet setup. Unfortunately I do not know that would be possible with a 4g63/64. Full boost by 2500RPM and ~450ft/lbs just seems way too optimistic IMO from what I have seen.

 

I wasn’t going to get into the technical details, but I can see that no-one is going to believe me if I don’t explain :-) I thought of adding a supercharger as a twin-charge setup, but even that would struggle to get that sort of torque down low – I realize it’s pretty much impossible to get that from a 2L engine by itself. That’s why I’ve added an electric motor to complement the turbo – elec gives heaps of instant torque at low rpm, and then the turbo takes over at high rpm. (I’ve built a few electric vehicle powertrains before, so that’s actually my specialty.)

 

Interesting concept. Where would you put the electric motor? And once you do put it in how are you going to adjust the car balance so that the handling isn't compromised?

 

I would rather aim for a flat power curve personally. Flat torque curves tend to result in an ultimately "peaky" power delivery for an equivalent peak power figure. A flat power curve is probably easier with a smaller turbo, basically make a strong motor - run it on alcohol, tune the boost curve to suit the power level you want and the torque will peak early and steadily drop.

Throttle will end up being more like "thrust" as it will basically result in the same hp at whatever rpm you nail it at - have done that kind of thing deliberately on a car which had too small a fuel system for the flow potential of the turbo to maximize the "go" we could get out of the injectors it had at the time and it ended up being quite a hilarious car to drive... albeit lacking the impression of top end "rush" that you'd have with the flat torque curve.

I have tuned a car with as close as dammit to the torque/power curve you describe there with a high compression NA Honda however, sweet as if you are content with only 260whp

 

Show us when u have done this. LOL

 

I'm now very confused. You want instant tq but do not want to run a bigger engine such as a V8 because you do not want to ruin the handling dynamic of the evo. I understand that, however please explain to me how installing electric motors as well as batteries to power these motors isnt going to add significant weight thus impact the handling of the vehicle.

 

Trying to get a V8 torque curve out of a 2.0L motor at those power levels is stupid. There is no way to do it that doesn't A) Cost beyond what you would get just buying a C6Z06 which would have the power dynamic you desire and B) Totally disrupt the weight of the car. Twincharging, big motor swap, electric motors/batteries all of them are heavy and expensive.

If someone wanted to do this just for a fun project I can understand it, but taking a torque curve as your target and building a car around a torque curve is a terrible idea. Why not use a platform that matches the driving characteristics for the type of driving you prefer?

 

OP, while I see what you're suggesting as novel and interesting, you will inevitably end up not being able to follow up.

What I suggest is this: get a ride in a 2.3L-2.4L stroker Evo with a small, fast spooling turbo like a ball-bearing BBK Full. I'm pretty sure 200 wtq at 2500 RPM and 400+ WTQ at 3400ish RPM will give that instant response you so desperately crave. Otherwise, C6 Z06 with boltons + E85 will give you roughly 400-450 wtq at 2000ish RPM...

 

And on top of that ^ dont forget too that the super short gearing in the evo's really convey quite a bit more feeling of instant torque than you'd think. There is a LOT of punch in the first 2-3 gears of the evo. A proper set up for sure will make you more than happy without worrying about that super flat curve.

 

Exactly. The gearing in Evo's is monstrous. Even off boost the stock 2.0L has plenty of torque and go, and spool is near-instant on a good stock frame turbo.

A 2.3L or 2.4L is even more torque-y everywhere. I get the feeling OP has never even driven an Evo...

 

Could always just swap an LS1 into it for that kind of torque curve.

 

Thanks for the feedback guys, I'll look into those other options...

I've considered the weight and I don't think it will be an issue because:
a) the electric motor is only 22kg, plus controller of 8kg
b) it's weight can be partially offset by removing the alternator, starter motor and starter battery (can use tiny 12V battery to turn on contactors for main battery pack, which uses electric motor to start engine; use much lighter DC-DC converter instead of alternator)
c) The battery pack would be small, high power cells, which would weigh about 70kg or so (with cooling, BMS, connectors, enclosure frame etc) and would go into the boot, so would actually improve the weight distribution.

I do admit the price is a huge barrier, so if there is a better way to get a similar result I'm all ears!