revs drop - induction kit

hi

ive just fitted a max power filter on a puma, the revs just keep dropping off every few seconds and then they go up again but sometimes engine just stops

anyone know whats going on here???

cheers

Reply to
* h3r0 *
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Yeah man, leave da damn car tunin' wo'k t'dose uh us who know whut we is hangin'. Could ya' strip some car engine, completly re-condishun it, put it back togeda' den gots it run faultlessly fo' anoda' ten years, even dough it wuz some metro engine. No?? Well duzn't touch nuthin den. 'S coo', bro.

Steve

Reply to
»»»Mr Fix All«««

Like all fords which use hot film air metering these days, altering the induction system so there very little or no depression in the trunking upsets the ECU. The non standard filter has probably set up some resonance in the trunnking at idle too- where the air now moves in pulses back and forth rather than steadily.

They are designed to work with alittle depression and no resonance.

Put the standard air box back, use a K&N panel filter in it, and modify the pick up trunking. You'll probably be better off anyhow as you wont be sucking up hot underbonnet air which would be negliating any bonus in hp from the cone filter.

Tim..

Reply to
Tim (Remove NOSPAM.

oh look another helpfull message!! if u aint got anthing helpful to say then dont say it, dam foo

Reply to
* h3r0 *

Try putting it back onto the normal ducting and see if the problem goes away. That would be a big clue.

You have still got the MAF inline? Any trouble codes coming up on your diagnostic computer? ;)

Reply to
Questions

thanx, just needed a re tune :)

va va voooom

Reply to
* h3r0 *

I wonder about this.

Clearly, warm air will mean less oxygen in the cylinder and so you need less petrol to burn in it, but the EMS is going to adjust the fuelling based on the real mass of air going in so all should work fine. It's really no different to the usual front ducting on a hotter day - that works ok.

This is at tickover, too. You'll use less fuel while ticking over, the power output at tickover is obviously not relevant to anyone so using less air and fuel is good.

Once you start to move along, the air in the engine bay will be replaced increasingly rapidly and the temperatures are going to lower as cold air comes in at the front and hot air escapes behind.

At this point, the question of power becomes more relevant, however the difference between hot air and cold air is that you would use less throttle at part throttle with cold air as you're getting enough air for the fuel you want to use, it being more dense.

With warmer air, you use more throttle but the same quantity of fuel in either case as that is directly related to power output.

At wide open throttle, the cold air can provide more oxygen in a given volume but, equally well, in conditions of wide open throttle, restriction on airflow through the ducting is going to be increasingly a factor for the cold air inlet, and the hot air inlet approach will be approaching the coldest air conditions, at higher speeds where the airflow through the engine bay is considerable.

IOW, I'm not sure that the warm air issue is anywhere near as relevant as it is sometimes described, albeit that if you play with the inlet ducting on a modern car you have to know what happens inside it and what the consequences will be if you change it anywhere.

Reply to
Questions

Yeah, you fitted a piece of crap that isn't worth pissing on and the engine managment is having a hard time coping with it. Either take it off and set it on fire or go spend £100 having it set up on a rolling road.

Reply to
Conor

On the Ford, it also adjusts fueling and ignition timing on the temperature of the air entering the donk. Kermit's behaviour is quite different when he's ingesting hot air. It gets up to over 70°C with the _standard_ induction system (besides the K & N panel filter).

Maybe. But when it's ingesting hot air, the engine revs take _forever_ to pick up.

Yes, one would think so, however the difficulty is that it takes some time for this to happen - it's not as quick as one might think. Part of the resaon is that there's not that much space under the bonnet for air to escape.

I've measured the temperature of the air under the bonnet in the Ka, not the Puma. The Ka's bonnet is slightly smaller, and there's an engine producing slightly less heat, and it stays hot (over 50°C) for over twenty minutes.

Why the significance of 50°C? Above this temperature, the engine's responses are much duller, under this temperature it feels just fine.

Yes. Slapping on a 57i and expecting more performance is a sign of believing too many websites! :)

Reply to
DervMan

It sounds like your engine speed is hunting.

:)

As other posters have suggested, you've likely upset something. "Induction kits" are, in my humble but having experienced too many of them, a waste of time and money unless you have a sealed induction system. Simply dropping a

57i, or similar, filter onto the intake just produces more noise - and lets the donk absorb plenty of hot air (which is covered elsewhere).

You might not think it's the case, but Ford have carefully set up the induction system, and banging on an induction kit that's been designed to look funky and sound noisy, isn't going to do jack for the performance.

Reply to
DervMan

Stripping the interior would offer as much performance difference as a bolt on air filter. Citroen axgt's actually LOOSE 4bhp on the rolling road when you swap the standard air box for the k and n filter (the mixture goes weak ... we're talking carburetors here). But then if you fit the little gold jet which k and n supply ... you gain 7 bhp over stock. (How many muppets threw the gold thing away .... doh homer simpson style).

Get a good performance cam in there, then do the easy stuff later (air filter, centre exhaust box "tuned" to engine .... your choice of back box,etc).

Reply to
»»»Mr Fix All«««

Ford puma: Nice car but 125bhp hauling 1050kg = 119 bhp per tonne. Citroen ax: Ugly car but 128bhp hauling 720kg = 177bhp per tonne.

Ok, mine has 50 percent more bhp than stock, but then if yours was modified as well to have 50 percent more bhp than stock, it would be:

188bhp hauling 1050kg = 179bhp per tonne.

But can an old ford engine rev to 8250rpm to produce the torques more often, making more horses???

Reply to
»»»Mr Fix All«««

Can you make one post where you don't mention your AX's power to weight ratio :) ?

Reply to
Dan405

In news: snipped-for-privacy@uni-berlin.de, Dan405 decided to enlighten our sheltered souls with a rant as follows

Is this where I pipe up with 528 bhp Sapphire Cosworth, 1340kg = 388 bhp per tonne?

Incidentally, with a K&N cone filter instead of the K&N panel one, it produced 504 bhp... and was beginning to pink so the run was aborted.

I wish I'd not sold that bloody car..

Reply to
Pete M

Are you still on about this AX?

The Puma's a much more civilised piece of kit...

Reply to
DervMan

D'oh, beaten to it, but add in the BMW bit too! :)

Reply to
DervMan

Can I mention my Locost here ?

130bhp - 602Kg.

:-)

Reply to
Bob Sherunckle

Hehehehehe!

Reply to
DervMan

The thing is, the PCM is adjusting things like timing and fuelling based on temperature, therefore it doesn't matter all that much. My carb based car doesn't have that at all, so air temperature should be highly relevant.

It has a big pancake filter up against the underside of the bonnet in the V, and draws air from all directions, most of the racers have the same setup and, aside from some making ram air ducts and things that I'm not convinced are doing much for them, (they don't tend to be copied by the actual winners.)

Mind you, it's drawing up to 400 cubic feet per minute, which is something like a few to several cubic feet per second, this may alter the dynamics of airflow under the bonnet compared to a small engined car.

Yeah, I sense this in practice, but a dab on the throttle results in a little bogging down, then a thirsty, sucking noise as the engine picks up.

I haven't measured this.

Pretty sure my engine bay refreshes much, much faster than this.

Apart from anything else, it's prone to overheating and the electric fan pumps lots of air through. When there was a viscous fan, a dab of throttle could lower the temps quickly, simply by pumping the heated air out of the side and top bonnet vents.

This may well be quite different in a modern, PCM / injection car, though.

Don't really notice a variation, mine seems to run about the same in the middle of winter as in summer.

This could be carb related, i.e. in hotter air, I am probably running richer. cold air, leans the mixture. If tuned about right, I suppose it would be a correct mixture on hot days and be wasting a little oxygen on cold ones.

Not cat, and none of this closed loop fuelling to alter things based on temperature.

It's a summer car primarily, so should / would be tuned that way round. If I was racing it, I would probably tune for the conditions (and more likely than not weld a roof / roll cage into it.)

Oh, I don't think I'm about to buy a "bolt on 100 bhp" spark plug lead set from a dodgy website any time around now. I'm just trying to work out why practical experience doesn't tie into theory all that well on this subject.

It might be that the cars I've examined from track events and things, which almost exclusively use pancake designs with hot air supply, and if not are using conical filters, it might be they have no choice for some reason. I know for a fact this is not because of the formula they're in.

My perception is the pancake like what I've now got, is permitting a lot more airflow than any valid ducting, and this is more important than the temperature of the air entering the carb.

I'm not just guessing, the JWR lower manifold I tried out restricted airflow significantly, and while it may have been better at part throttle on cruising or whatever, the 360 degree I put back on after trying it, was way more what I wanted, loads more power and much freer revving.

And when the engine had a pent head with twin SUs and cones, and before that with the ducting, it was pretty gutless but much smoother. When the cones fell off, which they repeatedly did due to lack of space and the engine scraping them off against the bonnet, the car ran about the same with and without, so ended up running without. Didn't seem to do any harm as such, goodness knows why. Either way, I'm quite content with the pancake and 360 on the holley, there may be better setups (like a performer and Weber) but price per inch of rubber deposited on the road makes this fine for the time being.

If I can be persuaded, I might do some runs with various arrangements to compare what's going on, but I doubt this would be much use for those who are on injection type engines where the game is probably a lot different. Still, I've got kit for measuring motion / temps / accelerations reasonably easily. Might do that just to see what it throws up in practice. What duct design would you recommend?

Reply to
Questions

Long but informative! :)

[snip]

You're right, to a point - except it runs a bit different when it's ingesting hot air. The pick up is significantly lower, and it's as though there's a big hole where there was a great big dollup of low down torque.

Quite possibly!

Hehehehe! The little Endura-E's responses are much worse when it's breathing in hot air. Given that the ECU uses code that's designed to save the trees :) it's probably deliberately doing funky things to preserve emissions, rather than performance.

On the motorway, this morning, the ingested air was at 32 degrees.

For the wee Ka, drive around York's ring road in the summer with the air conditioning open, park up, open bonnet, step back. It's hot under there - far hotter than in any of my other cars...

Lucky!

Right. We don't have vents, and I'm still looking for a subtle solution that doesn't shout, "look we've vented out bonnet" to everybody. Side gills may well work, but they're awkward to fit to the Ka.

Aye, we tend to run at 15 degrees hotter than ambient on the motorway, rising to degrees hotter in the city, like sixty.

Aye, I wasn't saying that _you_ thought so. But there are a lot of people out there who believe what they read on t'internet... :)

Hmmmm. NACA is supposed to be aerodynamically efficient... but I can't help you there. Certainly the little "cold air feeds" that you get with some cone filters are inadequate... not that this helps...

Reply to
DervMan

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