How much power is enough?

[AceOfHearts]

I know that the answer will probably whatever you have is never enough but it would be interesting to get peoples views on this.

At the moment my 4.0 Chim is making around 220bhp. This winter I am getting the engine rebuilt and turbocharging with the hope of around 350bhp, but with all of this outlay I don't want to be in the same position in a few years time (wanting more).

I want the car to still be usable and good for European jaunts, going to work in the summer and track days. Everything basically.

With this in mind will I be totally happy with 350bhp? Should I spend the extra now at this stage (probably an extra £3k or so) getting a 4.6 with forged internals built with the possibility of up to 500bhp?

What are your thoughts?

[sapper]

I have a 4l turbo with 360 bop and it's more than enough for just about any situation.

[AceOfHearts]

sapper said:

I have a 4l turbo with 360 bop and it's more than enough for just about any situation.

Thanks, that is reassuring. Out of interest what injectors are you running (I need to start getting bits ready for the conversion)

I think the worry I have is that I have been spoiled by motorbikes in the past, but I know acceleration in a car is a different sensation all together

[Discopotatoes]

too much is just about enough

[N7GTX]

I too have the 4.0 turbo with 355 bhp and (to me at any rate equally important) 481 lbs/ft torque.
The car does go really well and on a dry road the rear will snake on full power in a straight line from 40mph. I took a mate out in it and he thought it was still a driveable car when we were back in traffic. The only concern I had was if the gearbox and axle could take the power and Dom at Powers suggested going much higher and then there might be early failure of those parts.
His parting words though were, 'if you fit bigger injectors we can get a lot more. Maybe next year?'

[KateV8]

Interesting question. Our car, like yours, began at 220bhp at the time we bought it four years ago. Through various stages of tune the power went from 220 to 280, then around 300,then a big jump to 400 and now around 450. And if I'm honest it was fine once it passed 300, fine in that the power to weight ratio made it feel very quick and very driveable. Don't get caught up in the numbers game, it reaches a point where the power exceeds the cars' ability to use it and then it's a question of what use is a surplus? Of course it depends what you want to do with car, there are people on here who want to do standing quarter mile sprints and fair play to that section of owners, for fast road use you need to think about keeping the car in balance and paying attention (and money) to suspension and brakes too. Your turbo plans will give you a very nice driving car which will already be far too fast for public roads if pushed.

[AceOfHearts]

Thanks for the honest replies everyone

I agree that the main thing is that I want the car to remain a well balanced package. There is no point having tons of power if you feel like it just wants to spin the wheels every time you go near the throttle.

Like you say there are so many big projects going on in the forum its easy to get sucked into a numbers game, which I really don't want to do.

I will carry on as planned with my 4.0 Turbo project. I'm sure I will be happy with a 60% power increase

[Hoofa]

The problem is if you chase bigger numbers something is going to break, your then into updated drivetrain etc, with mine ii have a problem getting the power down, with the traction control on you can feel the car power being rained in under acceleration. You could almost say that power is wasted, you not wrong with your thinking and go for a nice drivable car

[jamienshelly]

I am seriously considering a turbo upgrade on our 400, only a low pressure system as the engine is well over 100K and still on the old 14cux, I am not chasing ponies although 350-375bhp would be really nice. I just want a car that is quicker than standard, a little different but is drivable. I was thinking of a single Garrett t28 or maybe even 2 t25's running around 5psi through an intercooler. being new to this FI scene would I need higher flow injectors and RR pressure regulator and what gain would I expect to see with either option and would I need an alli rad? as I assume I will need extra cooling.
Sorry for the hijack and barrage of questions.

[OleVix]

jamienshelly said:

I am seriously considering a turbo upgrade on our 400, only a low pressure system as the engine is well over 100K and still on the old 14cux, I am not chasing ponies although 350-375bhp would be really nice. I just want a car that is quicker than standard, a little different but is drivable. I was thinking of a single Garrett t28 or maybe even 2 t25's running around 5psi through an intercooler. being new to this FI scene would I need higher flow injectors and RR pressure regulator and what gain would I expect to see with either option and would I need an alli rad? as I assume I will need extra cooling.
Sorry for the hijack and barrage of questions.

you should definately give the engine a refresh before doing that! New seals and shells and you get to check the oil pump system/ strainer. Mine was full of silicone and gunk. A turbo would have killed my 400!

[jamienshelly]

The oil pump and system is good, and will recheck the on the install as the sump has to come of anyway, As far as a rebuild goes, I have future plans of a 4.6 build and if the 400 doesn't like the turbo then the 4.6 may come sooner than expected. I think the engine is in fairly good order from the checks I have done and I hope that 5 psi will not strain it too much

[AceOfHearts]

OleVix said:

jamienshelly said:

I am seriously considering a turbo upgrade on our 400, only a low pressure system as the engine is well over 100K and still on the old 14cux, I am not chasing ponies although 350-375bhp would be really nice. I just want a car that is quicker than standard, a little different but is drivable. I was thinking of a single Garrett t28 or maybe even 2 t25's running around 5psi through an intercooler. being new to this FI scene would I need higher flow injectors and RR pressure regulator and what gain would I expect to see with either option and would I need an alli rad? as I assume I will need extra cooling.
Sorry for the hijack and barrage of questions.

you should definately give the engine a refresh before doing that! New seals and shells and you get to check the oil pump system/ strainer. Mine was full of silicone and gunk. A turbo would have killed my 400!

+1

Mine is currently at 115k hence deciding whether to rebuild this or go to a 4.6. I had considered just putting the turbo on the current engine but rebuild costs were reasonable and means I can put a new clutch in at the same time and tidy up the engine bay a bit

Plus my engine is still on its original cam so is probably not in its first flushes of youth

[phazed]

Hoofa said:

The problem is if you chase bigger numbers something is going to break, your then into updated drivetrain etc, with mine ii have a problem getting the power down, with the traction control on you can feel the car power being rained in under acceleration. You could almost say that power is wasted, you not wrong with your thinking and go for a nice drivable car

Good words learnt by expierience no doupt.

If you stick to a max of 400 bhp and 450 isn torque, couple that with the very best tyres and well set up suspension you will be OK.

Any more and you will break things and end up in a bush backwards unless you give it full concentration all the time.

My car is really well set up, runs Toyo R1Rs on the road and isn't scary at all You are more then welcome to a spin if in the area as it runs similar power to a turbo, (377/460) although a wider torque curve.

I can accelerate flat out in the dry with a little care in first but more importantly, mid range acceleration is fantastic, seemless power up to flat out.

The down side is that given a little rain you will have to be solo careful. I have experienced wheel spin at 80 in 4th on a damp motorway!

https://www.youtube.com/watch?v=rOu_zZfSU8g

[N7GTX]

OleVix said:

jamienshelly said:

I am seriously considering a turbo upgrade on our 400, only a low pressure system as the engine is well over 100K and still on the old 14cux, I am not chasing ponies although 350-375bhp would be really nice. I just want a car that is quicker than standard, a little different but is drivable. I was thinking of a single Garrett t28 or maybe even 2 t25's running around 5psi through an intercooler. being new to this FI scene would I need higher flow injectors and RR pressure regulator and what gain would I expect to see with either option and would I need an alli rad? as I assume I will need extra cooling.
Sorry for the hijack and barrage of questions.

you should definately give the engine a refresh before doing that! New seals and shells and you get to check the oil pump system/ strainer. Mine was full of silicone and gunk. A turbo would have killed my 400!

^^^^^ this.

My engine had 'just' 50,000 miles on it but before Powers would fit a turbo they did a partial strip as the cam would in any case be past its best. Just as well they did. Cam bearings were scored badly and checking the mains and big ends found them blackened and worn. So went for the full works engine rebuild with a warranty. Be careful!

[V8 GRF]

KateV8 said:

Don't get caught up in the numbers game, it reaches a point where the power exceeds the cars'driver's ability to use it and then it's a question of what use is a surplus?

I think a lot of people also forget the part I've edited as well......

[KateV8]

V8 GRF said:

KateV8 said:

Don't get caught up in the numbers game, it reaches a point where the power exceeds the cars'driver's ability to use it and then it's a question of what use is a surplus?

I think a lot of people also forget the part I've edited as well......

Agreed.

[Bluebottle]

phazed said:

Hoofa said:

The problem is if you chase bigger numbers something is going to break, your then into updated drivetrain etc, with mine ii have a problem getting the power down, with the traction control on you can feel the car power being rained in under acceleration. You could almost say that power is wasted, you not wrong with your thinking and go for a nice drivable car

Good words learnt by expierience no doupt.

If you stick to a max of 400 bhp and 450 isn torque, couple that with the very best tyres and well set up suspension you will be OK.

Any more and you will break things and end up in a bush backwards unless you give it full concentration all the time.

My car is really well set up, runs Toyo R1Rs on the road and isn't scary at all You are more then welcome to a spin if in the area as it runs similar power to a turbo, (377/460) although a wider torque curve.

I can accelerate flat out in the dry with a little care in first but more importantly, mid range acceleration is fantastic, seemless power up to flat out.

The down side is that given a little rain you will have to be solo careful. I have experienced wheel spin at 80 in 4th on a damp motorway!

https://www.youtube.com/watch?v=rOu_zZfSU8g

I'm with these two ^^^...these are very light cars and you are restricted with tyre tread width which, is really your limiting factor to how much power you can actually use.. in the wet mine light the rears up at 125mph if i'm not careful

[jamienshelly]

I completely understand about checking and replacing worn parts, but I am meaning I don't want to go all forged and super low compression etc, just to run 5 psi in an old engine. I will get the 4.6 block and build a strong engine, fit the system and increase the boost, in the interim I will just enjoy the 400 and the introduction to FI.

[Jhonno]

IMO you always get used to power.. 350 isn't "a lot".. I'd spend the extra (if it is disposable income) and give it room to tweak in future for more fun.

[N7GTX]

Jhonno said:

IMO you always get used to power.. 350 isn't "a lot".. I'd spend the extra (if it is disposable income) and give it room to tweak in future for more fun.

This is what I've done. Because I know I'll get used to the shove in the back when the turbo comes on, that next year I'll forget my promise to leave well alone and end up with bigger injectors maybe definitely