44 replies to this topic

[fenghuang]

Having just read about the reasons you shouldn't fit certain components to a road car, I'm interested to hear people's thoughts:

Of the common performance mods done to Minis, what should not be done on a road car, and more importantly, the reasons why?

Edited by fenghuang, 19 October 2015 - 06:53 AM.

[Dusky]

It increases bhp in the top half of the rev range ( think its above 5k rpm) and loses bhp down. Bang for bucks Theyre way overrated imho.

[AlexMozza]

Fitting a stage one kit, but not changing the needle :)

[fenghuang]

[red herring]

Edited by fenghuang, 19 October 2015 - 06:53 AM.

[blackbelt1990]

Ahh ffs... Glad mine only does a few hundred miles a year then!

[fwdracer]

Such a load of rubbish being spouted about 1.5 ratio rockers on here (this whole forum).

 

My road motor did 80K with a set on and the cam was fine - used on a standard Rover profile. They increase lift. On a sort duration cam they are a brilliant bolt on for road engine to assist cylinder filling and breathing. Those with roller tips decrease side loading on the valve guides, ensuring better valve guide longevity.

 

Eighty thousand miles. Read it again. No problems.

[mingy]

Such a load of rubbish being spouted about 1.5 ratio rockers on here (this whole forum).

 

My road motor did 80K with a set on and the cam was fine - used on a standard Rover profile. They increase lift. On a sort duration cam they are a brilliant bolt on for road engine to assist cylinder filling and breathing. Those with roller tips decrease side loading on the valve guides, ensuring better valve guide longevity.

 

Eighty thousand miles. Read it again. No problems.

Well said that man, If an engine is built by someone who knows what their doing ie: Swiftune, MED, and the likes then, the inclusion of highlift rockers to complement the performance of the build is a must and well proven.

I have them fitted to my 1380 with a Kent 286 cam and, both the engine builder and the rolling road technician said they will be beneficial without any premature wear or damage to other engine components.  

[Dusky]

It increases bhp in the top half of the rev range ( think its above 5k rpm) and loses bhp down. Bang for bucks Theyre way overrated imho.

Assuming you're refering to high lift rockers, ML say it's because they cause premature cam lobe wear, leading to metal shards trashing things like main bearings.

3 words: use quality oil.

[ACDodd]

No road engine of mine ever has these fitted.

AC

[jaydee]

The use of wrong valve poudage is worst than fitting 1.5 rockers

[Cooperman]

The OP's question is very general and it depends on how the car will be driven on the public roads. If you modify it for absolute performance it will not be nice to drive on the roads and at that level it will be a sure path to getting a driving ban.

 

So what does a road car need?

 

Good mid-range torque.

Ability to cruise at around 70 mph with no excessive engine wear.

Acceptable acceleration, bearing in mind that the Mini is a classic car.

Good road-holding on normal (i.e. a bit bumpy) roads

Predictable handling.

Reasonably quiet exhaust system

 

Whether or not to use a 1.5:1 rocker ratio is not important in performance because all it gains is a few bhp at the higher rev range. The key to better performance with no appreciable loss of mid-range torque is a well gas-flowed head, the correct compression ratio of between 9.5:1 & 10:1, the right ignition curve and a cam giving best torque at around 3800 to 4000 rom with peak power at c.5600 rpm.

An induction and exhaust system capable of flowing the extra combustion mixture and the consequently higher exhaust gas volume at the correct inlet and exhaust gas velocities and am final drive ratio to make best use of the improved performance figures are also very important.

Engine build quality is very important.

 

The real gain in road performance, however, is obtained by accurate and optimised suspension settings and brakes.

 

Too many owners set their cars up to some extent like track-only cars, then don't like the road performance, although having spent a lot of cash on doing this they then don't like to admit to others that the car is far from ideal..

[Ethel]

1.5's would be better thought of as "rapid" rather than "high" lift rockers. Getting the valves more open sooner is their universal benefit. More lift on a cam that's already been optimised for lift is just wasted energy, but it can be a benefit to a more mild cam - like the one in your factory spec engine you don't want to dismantle to fit a new cam. Accelerated wear comes from increased valve spring loads (magnified by the extra rocker ratio). If you aren't uprating your springs then the rockers will give you more revs before you encounter valve bounce, a potential benefit for those who don't subscribe to the "more is better and too much is just right" tuning philosophy.

 

I think I'd put fancy plug leads and high energy coils on the list of not needed road mods. Though getting the ignition right is important and you should be prepared to budget for controlling it as keenly as you would for the fuelling and exhaust.

[MIGLIACARS]

The OP's question is very general and it depends on how the car will be driven on the public roads. If you modify it for absolute performance it will not be nice to drive on the roads and at that level it will be a sure path to getting a driving ban.

 

So what does a road car need?

 

Good mid-range torque.

Ability to cruise at around 70 mph with no excessive engine wear.

Acceptable acceleration, bearing in mind that the Mini is a classic car.

Good road-holding on normal (i.e. a bit bumpy) roads

Predictable handling.

Reasonably quiet exhaust system

 

Whether or not to use a 1.5:1 rocker ratio is not important in performance because all it gains is a few bhp at the higher rev range. The key to better performance with no appreciable loss of mid-range torque is a well gas-flowed head, the correct compression ratio of between 9.5:1 & 10:1, the right ignition curve and a cam giving best torque at around 3800 to 4000 rom with peak power at c.5600 rpm.

An induction and exhaust system capable of flowing the extra combustion mixture and the consequently higher exhaust gas volume at the correct inlet and exhaust gas velocities and am final drive ratio to make best use of the improved performance figures are also very important.

Engine build quality is very important.

 

The real gain in road performance, however, is obtained by accurate and optimised suspension settings and brakes.

 

Too many owners set their cars up to some extent like track-only cars, then don't like the road performance, although having spent a lot of cash on doing this they then don't like to admit to others that the car is far from ideal..

another well worded quote from a man who has been there and done it...

[blackbelt1990]

I wish I could just get Cooperman to set my car up! Lol

[Cooperman]

I can't seem to get time to do my own Minis at the moment. I've just bought a L-R Discovery 300TDi as a tow car and am in the middle of servicing it, cleaning it (it was filthy inside, but not any more), and doing a few small jobs to make it fit for towing. I've also got Grandson's MGB to finish the basic body restoration as it needs the wings and doors restoring, trial fitting, removing and painting. I'm just re-skinning the 850 doors ready for the final trial fits of doors, bonnet & boot, before stripping for final priming and painting.

In addition to all this, I'm carrying out a major re-design and fabrication for a big modification to our 12 litre diesel winch at my gliding club which has to be completed by the end of January 2016.

It's a good job I'm retired as I would never have time to do a 'proper' job anymore  .