mods for non-turbo 2.5 850?

[Cypher007]

im interested in any mods that can be applied to a non-turbo 2.5 20v 850, nothing to drastic please. so far ive istalled a BMC panel filter, Bosch super 4 plugs, and im currentley looking for a way of making my own de-cat pipe, any ideas and supplier links would be apprieciated.

maybe theres some way of putting a air scoop box behind the front grill?:dude:

[Hank Scorpio]

My gf' and a friend of mine both have na 850's. We've done a simple couple things to his. First, we put a new accel coil on from www.easternaerospace.com then did a K&N air filter. He did relocate his air inlet, though I can't remeber where too. Pretty much though, those are the only simple ones I know of.

[shedend]

There is not alot you can do on the cheap to a Non Turbo. Replacing the filter with a K&N might give you problems with the ECU. The injection system needs warm air to function correctly. The standard Volvo setup does this as just about best as it can be done.
Removing the CAT will not do much good to the mangement system either, your best bet is to get a decent exhaust.
You can go down the port polishing/head skimming road but it is expensive. I've looked at putting a 850R clutch/flywheel in mine but it ended up being more bother than it was worth.

[ChrisB]

Warm air? Back in the old days with carbs maybe. Fuel injected you don't need to worry about fuel atomisation problems. You want the coldest air you can get (cold are = more dense = more charge in cylinder = better burn = more power).
I forget the figures, but it's something like a 4% loss in power for a 10 degree C increase in intake temp.

Keep the airbox, mod it with a nice big fat intake pipe (the one that feeds into the box). Postion the pick up in a high pressure area that gets cold air at the front of the car (behind grille, lights or cut a big hole in the bumber :D ).

Engine management systems only really have problems with removing the Cat if it has an oxygen sensor both before and after. Dunno about the 850, but i doubt it does have one after the cat. Don't expect massive gains though, but you should be able to feel a difference, should be a little better high up in the rev range.

Reseting the ECU is always a good idea if you change something on the engine (de-cat, new air intake etc). Just about all modern ECU's are self learning and will learn how to make use of the changes.

[Hank Scorpio]

True. Warm air is the enemy of any hi-performance motor, including carb cars. You only want some warm air to help warm the motor up, but it's really not nessacary most of the time.

Porting and polishing, cam and big-bore throttle will net your biggest returns. An Exsaust will make a huge difference then, but not as much stock.

Most people don't realize this but, putting a larger cat-back on that the head pipe will actually yield less power than going all the way back with the same size, or smaller as you go back (but over all larger). IE 2" stock into a 3" cat back system will be less than a 3" going into atleast a 2.5". Exsausts act as big venturi's and if you open them wider towards the end the velocity of the exsaust slows down, and you loose power. Go w/ a big all the way back or a big into a slightly smaller cat-back and you will have a much better performing car.

[ChrisB]

Warm air intake systems are common place on carb cars to stop carb icing. Also single point injection systems. Proberbly not a problem in most of the US.


I'm a member of the 'as little backpressure as possible after the tuned section of the exhaust brigade'.

For turbo cars this is everything post turbo. For NA cars this is usually just before the cat.

[Dan]

IPD in Oregon has some mods for the 850's altho I'm not sure if its for the NA cars. The newer cars are hard to modify easily or cheaply. The factories spend 1000.00s to get that last horsepower out of their cars. The only way to get more power easily is to give up something else, like lowend torque, noise (subjective of course), fuel economy or reliability. Usually on these cars you need to spend big bucks on a chip upgrade along with an exhaust and intake. I would plan on spending a big chunk of cash to do it properly. I am going through this on my 2003 Mitsu eclipse right now. I have changed the tranny fluid and motor oil to Amsoil which is supposed to free up a bit of power and seems to but it is hard to tell. I am experimenting with plug gaps and am trying to gather data on aftermarket intakes to see if they really do add any power (most add a couple of horses at the top of the rpm band). Most cheap gains come from optimizing what you already have. Knife edge your throttle plate, gasket match your intake and exhaust and other mods of that ilk. There seem to be very few mods on the market that really do anything except lighten your wallet. There are a lot of cars slower than stock due to cheap aftermarket stuff. Sorry if this is not laid out in a coherent form, it's late and I am tired. Just wanted to share my 30 years of experience trying to hop up my cars. Dan C :sleep:

[Hank Scorpio]

Dan's right. NA upgrades on modern cars are difficult and costly to do. It's not like the "good old days" of carburated cars where you could do just about anything, and alot on a budget.

If you really want a volvo to build up and be quick, look at 240 turbos and 7- series turbos. Not much computer controlled stuff on them, and they can be coaxed on a fairly mild budget.

[ChrisB]

You shouldn't gasket match the exhaust ports. The step helps pulse seperation for cylinder scavaging (stops the gasses being sucked back in on cam overlap).

If you're tuning properly you wouldn't touch 'chips' you're just replaceing one set map for another set map. You would be looking at a piggiback ECU or programmable management to make the best of what _you_ have, not what _most_ of the same model car have.

[Dan]

Ya, Chris is correct on the exhaust port matching and the comment about the chips. If I was more awake at the time I posted, I would have not needed this correction. Thanks for the correction. Dan C

[ChrisB]

Do you have the Dastek Unichip over in the US?

It's a pigiback ECU that allows you to fully map a car (fuel, ignition, boost) while retaining the standard ECU (for limp home mode, diagnistics, etc).
Getting more popular over here in the UK.

Also the Apexi and Blitz stuff seems popular amoung the jap car tuners too.

Much better than a 'Superchip'. Which usually just hack out boost cut limits and increase fueling and bring the engine closer to knock limit's.


But... back to the topic. Modern ECU's are actually very smart, if you have to go quite far on a NA car to reach the limits of the standard ECU. Personnaly i'd be looking away from chips and such when tuning in the first stages. Look towards gas flows and restrictions (exhaust, throttle, airbox, head). You should be able to gain 5-10% there on most engines.

[Hank Scorpio]

Originally posted by ChrisB
...But... back to the topic. Modern ECU's are actually very smart, if you have to go quite far on a NA car to reach the limits of the standard ECU. Personnaly i'd be looking away from chips and such when tuning in the first stages. Look towards gas flows and restrictions (exhaust, throttle, airbox, head). You should be able to gain 5-10% there on most engines.

I agree.

Hey, does that unichip work on K-jettronic?

[ChrisB]

I believe so.

It does it's thing by changing some of the sensor outputs that the ECU see's. So the ECU adjusts things and has no idea that there is another computer there.

Only thing i can't think of with the K-Jetronic system is that it's fuel only, and not all that great (fair bit of restriction with the vane type AFM). So it may be better to dump the lot and go for full management. Depends on what you want to achive though.

[Hank Scorpio]

true. Actually, the simplicity is what makes it nice!