Reliable power upgrades for 4.0 and 4.3L engines

[B19GRR]

Hey all,

So what can be done to get close to the supposed power of the 5.0L then? How far will things such as ACT inlet plenums and a Mark Adams chip take the engines before headwork and cams are needed?

BTW Joolz if you happen to browse this, do you do any chips for the Rovers?

Just musing my options, I'm very drawn to the concept of a legal decatted car for some reason

Cheers,
Rob

[2 sheds]

The 4.0L will need modified heads to make serious power, The 4.3 already has modified head, not difficult to equal 500 for bhp, the 500 will always have more torque though, the pre-cat engine will rev higher though.
Tim

>> Edited by 2 sheds on Saturday 6th December 22:50

[simpo two]

Don't forget the brakes and suspension to match... this is a road which shpub has travelled. I fear you migt be paying an awful lot for the 'legal' catless status!

[joospeed]

Rob :
my advice these days is to go for complete mapped systems, you can go for an aftermarket system, or a piggyback ecu onto the lucas and trim the advance, the unichip gives you plus/minus 25 degrees to play with ..

all this means that you can optimise any hardware mods you do, remapping the ecu as std only gets you fuelling, the ignition can't be done but is critical to getting hte car running smoothly and with full power coupled to the best mpg you'll get too (which is important these days)

[B19GRR]

simpo two said:

Don't forget the brakes and suspension to match... this is a road which shpub has travelled. I fear you migt be paying an awful lot for the 'legal' catless status!

Definitely not forgetting these. First plan of attack would be a visit to Joolz for Nitrons and a check on condition of bushes.wishbones. I'm right in thinking that the Spider wheel/brake upgrade isn't suitable for the early cars though? Can't remember why thoguh. Pretty sure there are other economically viable brake upgrades available though. Dare I display my ignorance and ask if the cars have S/S braided lines as standard? Can you get Pagid 42 pads to fit the Griff? These have totally transformed my Elise, admittedly not cheap though.

Joolz have you fitted a Unichip to a Rover yet, or worked with guys that do it? It strikes me as a nice elegant solution but does it really offer as much as a Tornado chip? I'm guessing a Tornado is a full ECU replacement here. How about an Emerald tweaked by Dave Walker himself?

How much higher do the pre-cats rev? I remember bouncing off the hard limiter on a 4.0 Chim at 6k and it making a noise that suggested I shouldn't have gone quite so high!

Cheers,
Rob

[simpo two]

B19GRR said:

How much higher do the pre-cats rev?

IIRC both the 4.0 and 500 were 6,000rpm. However if you start tweaking I'm not sure what the technical max is. But as max torque is below that, IMHO you're wasting your time thrashing beyond 6K because you'd be doing better in the next gear. I stand to be corrected though!

[jigs]

Might as well sit down, Simpo - this could take some time!

[joospeed]

Hi rob .. the unichip is better than just a rover ecu rechip, you can get teh fuelling bang on with both of them, but on the rechip route you're still fighting with a clockwork ignition system, so can only be right in a couple of places, and if you wind advance on you can't wind it off again higher in the rev range, hence you're always limited by the maximum advance at the detonation-limited point in the range.

best of all is though that the unichip price is fixed by dastek the manufacturer at around 500 - 600 pounds plus vat, can't remember which exactly but no matter how long they spend mapping that's all you pay, drive in drive out conversion.

John Nobles down the road from me have massive experience with these.

[Pies]

joospeed said:

best of all is though that the unichip price is fixed by dastek the manufacturer at around 500 - 600 pounds plus vat,

Thats illegal

[B19GRR]

joospeed said:

clockwork ignition system

yoiks, my brain just flipped!!!

[shpub]

2 sheds said:

The 4.0L will need modified heads to make serious power, The 4.3 already has modified head, not difficult to equal 500 for bhp, the 500 will always have more torque though, the pre-cat engine will rev higher though. Tim >> Edited by 2 sheds on Saturday 6th December 22:50

Depends on the 5 litre Tim....

[shpub]

The serpentine engines are better for high revs because of the improved oil pump design and the fact you can get distributorless versions (if you spend enough money). This removes one of the main wear points on the pre serp engines. The 520 has this and is quite capable of revving to 7500 although I limit it to around 6600 where it is still producing about 375 bhp. Ish.

1. There is no substitute for cubic inches.
2. If you want real performance fully mapped ignition and fueling is the way to go but it is expensive.
3. Suspension and brakes need to be upgraded otherwise no insurance. Especially if you want 320 bhp from a 4.3.
4. The more power the less driveable the car becomes as wilder cams start to remove the low down torque.

[2 sheds]

Ok so all the engine sizes will rev to around 6500, but the longer stroked variants will produce the peak figures further down the rev band, i had a Rover 5.0L that revved to over 7500 but you couldn't compare this to a TVR engine.
the smaller capacity engines will rev safely to a higher rpm, I've known racers that used bog standard bottom ends on both 3.5 & 3.9 blocks revving to well over 7000 with the idea that if they "blew up" it wouldn't matter too much, as the replacement cost would be low, they raced for years and survived.
I'm not saying that smaller is better than larger, but just explaining the revving bit.
Tim

>> Edited by 2 sheds on Sunday 7th December 19:35

[joospeed]

Pies said:

joospeed said: best of all is though that the unichip price is fixed by dastek the manufacturer at around 500 - 600 pounds plus vat, Thats illegal

maybe that should be RRP then?

[simpo two]

2 sheds said:

I'm not saying that smaller is better than larger, but just explaining the revving bit. Tim

I guess that's our old friend the laws of physics - ie small chunks of metal can change direction faster than bigger chunks...?

[shpub]

One of the main issues is the oil pump and distributor drive which is known not to like high revs. This then reduces the oil pressure over time and this does not do much for engine longevity. It is a possible contributing factor to early cam wear but don't quote me on that as Serp engines can suffer from it as well.

As for racers etc yes I agree. probbaly the main difference is that they change the oil almost everytime the engine is used. As for peak power , mine peaked at 6000 rpm in the Griff. I think it is very dependent on other factors.

Back to the original question: can you get 500 power out of a 4.x engine? The answer is yes you can get close without going very extreme but it will cost a lot of money and the car will be trading off drivealbility/longevity etc to get that power. Nothing to say it can't be done but it and the other mods needed are not cheap.

Big chapter on this in the bible. Whatever you decide good luck.

[B19GRR]

Thanks guys,

All good food for thought. What year/month/day/hour/etc. did the serpentine get introduced? Was it at the same time as the switch to T5 box or after that?

Steve, the bible is on order. Unfortunately I had to allow the gf to get me it for chrimbo otherwise she'd do unpleasant things to my delicates as she's always complaining that I keep buying myself goodies that she could be getting me instead

Cheers,
Rob

[simpo two]

B19GRR said:

What year/month/day/hour/etc. did the serpentine get introduced? Was it at the same time as the switch to T5 box or after that?

IIRC the serpentine appeared with the first of the 500s (1993 'L') but the T5 box followed a year or two later.

B19GRR said:

otherwise she'd do unpleasant things to my delicates as she's always complaining that I keep buying myself goodies that she could be getting me instead

She will do still unpleasant things to your delicates because when the bible arrives you will sit up in bed reading it from cover to cover and not seeing to her needs. At this time you can placate her and carry on reading undisturbed by giving her a handy list of single PHers phone numbers!

[Paul V]

The early 500’s were pre-serp with rover box, the T5 was then introduced with the pre-serp engine, then the serp engine came after that.

[simpo two]

Paul V said:

The early 500’s were pre-serp with rover box, the T5 was then introduced with the pre-serp engine, then the serp engine came after that.

Ah. I was completely wrong then! Doh...