OK, another question about my Golf 1.8T

The 'gains' can often be expressed in negative figures.

Ooh. That doesn't sound good. So pissing about with these things can actually damage performance?

Yup.

I've seen:

2" bore exhaust fitted to a 1L Mini which made it do around 20MPG and=20 it could barely make 60MPH.

K&N Induction Kit fitted to a 2L injection Astra that actually made the=20 car less powerful and it coasted on light throttle like a dog. Was=20 actually far faster once the original airbox was replaced.

--=20 Conor

How about taking the safety labels off everything, and let the=20 stupidity-problem solve itself?

Sounds nasty. What about putting in a new panel filter? I've heard that this can help things...? Cold air intakes supposedly increase torque too. Or is that another dodgy claim?

Russ

I can't believe you two, the OP is interested in modifying his car, and to be frank your advice is crap, you are trying to put him off, yet he has post in uk.rec.cars.modifications asking for advice? what gives?

Well, the theory behind it is sound. Cold air is denser. The denser it is the more air you get in, the more air the more power. However a lot of the cheap setups just end up sucking hot air from the engine bay and don't really work. I've heard good reports of the higher end kits, the BMC carbon setup and the Pipercross Viper kits are supposed to work quite well. Re: the exhaust, I don't really know much about them, increasing the bore too much can not give you enough pressure and stuff (that's quite obvious).

A nice well made stainless though can help if it's more free flowing, or has more efficient or no cats. Conor has just had a stainless fitted to the Capri I beleive, they also look nicer and sound nicer (if you choose the right ones...)

Taylor, ignore this numpty...

Cold air intakes can work if setup correctly, ie you can get a location which has good *fresh* air flow. This is not exactly the same as just sticking a cone filter on, you need to make sure the air being drawn in is not 'engine hot' or even worse 'turbo hot'. Sometimes a kind of firewall (for want of a better name) is provided as part of the kit to deflect the hot air and depending on the design and location these can sometimes work.

Ken

Thanks Ken. Are we talking a lot of money here and is it worth the trouble? Or is a straight remap going to produce better results for less hassle and much the same cost?

Russ

You'll get more power from the remap no doubt, but if you decide to do both, you should do the add ons first, then the remap so it can take advantage of them.

The advantages of the filters and pipes would be the sound (and stainless systems often have lifetime guarantees) and the looks.

Remap is really going to be better value but all the mapping companies recommend when you do this, that also replace two other items. Replace your panel air filter with a 'performance' equivalent (e.g. K&N) and replace the turbo pressure release valve as the VW one is weak and only gets weaker as the miles pile on. The Forge007 is a good unit and is as cheap as the plasticy VW one (also available in black so as to go unnoticed). Do not buy a 'dump' type valve as VW's engine sensors don't like these apparently (and they sound chavy ;-) )

Ken

Know what you mean about the dump valves. Might as well put a Cosworth spoiler on the bloody thing. Custom Cars just quoted me =A3350+VAT for a remap and recommended that I fit a forge diverter valve to cope with the extra boost. This is an extra =A380.00 fitted. I'm tempted...

Russ

Eh? A cold air intake needs to be *designed* for the car. Manufacturers don't just slap any old trunking on...

Remapping is the best way forward, full stop.

Or lightening the unsprung mass.

Some modifications are crap. If they are we will say so. If they genuinley work, some one will have used it and have dyno figures to say so (before and after).

Further to this, check to see if your car's inlet tract has some sort of cold air setup. All the Peugeots we've had (1991-2001) have had the intake nearly outside the car and at least forward of the radiator. They have all been diesel though.

There is a noticeable difference to how the car responds, even on the normally aspirated ones, when sucking air from inside or outside the engine bay as I found out by leaving the pipe from the air intake to the filter off by accident. It was more noticeable when driving in town.

Even in the best case scenario, a handful of bhp at most - nothing that you would notice.

Bollocks is it, their information wass spot on - especially surprising considering one of them was Conor :)

What gives is that this is not uk.rec.cars.max.power.stick.on tat

Aftermarket Air filters and exhaust and so forth *can* improve your power ever so slightly, but more often than not they can also leave you with slightly less power.

Their chief purpose for existence is not to make more bhp, but to make more noise.

HTH

DING! This was the problem with the Astra I posted about.

The trick is to use what works and not go mental.

All I've got is a second hand K&N filter bolted to a second hand=20

32/36DGV carb on the intake side and on the exhaust side it's a second=20 hand 4-2-1 fannymold of unknown make mated to a custom built 2" bore=20 stainless system exiting in a 2" I/D polished trim - non of this 3"=20 bollocks exiting in a dustbin at the rear that sounds like a Boeing 747=20 at takeoff. Also advanced the timing from the manufacturers spec to 14=B0 BTDC and increased the idle mixture to 2.5%.

End result is a nice civilised exhaust note, an increase in mid range=20 torque, a more freely revving engine which is noticably more powerful=20 and an actual increase in fuel economy of 3MPG which is roughly 1/11th=20 increase.

And I've still not managed to get it set up on a rolling road yet. Want=20 to change from points to electronic dizzy before I do that.

Total cost =A3390 give or take a few quid for gaskets. =A3100 for the carb,= =20 filter and fannymold and =A3293 for the exhaust. Now got a 20 year old=20

1.6L car with a 20 year old 1960's technology engine that can shove all=20 the local boy racers up one of the local steep hills I seem to meet=20 them all on.

--=20 Conor

How about taking the safety labels off everything, and let the=20 stupidity-problem solve itself?

I usually reckon on about 3-5BHP for a filter and that's after the car has been set up for it.

DING! This was the problem with the Astra I posted about.

The trick is to use what works and not go mental.

All I've got is a second hand K&N filter bolted to a second hand

32/36DGV carb on the intake side and on the exhaust side it's a second hand 4-2-1 fannymold of unknown make mated to a custom built 2" bore stainless system exiting in a 2" I/D polished trim - non of this 3" bollocks exiting in a dustbin at the rear that sounds like a Boeing 747 at takeoff. Also advanced the timing from the manufacturers spec to 14° BTDC and increased the idle mixture to 2.5%.

End result is a nice civilised exhaust note, an increase in mid range torque, a more freely revving engine which is noticably more powerful and an actual increase in fuel economy of 3MPG which is roughly 1/11th increase.

And I've still not managed to get it set up on a rolling road yet. Want to change from points to electronic dizzy before I do that.

Total cost £390 give or take a few quid for gaskets. £100 for the carb, filter and fannymold and £293 for the exhaust. Now got a 20 year old

1.6L car with a 20 year old 1960's technology engine that can shove all the local boy racers up one of the local steep hills I seem to meet them all on.