TII AIRFILTER - ADEQUATE FOR MORE HORSEPOWER??

[classicman]

Hi

My tii is tuned to Alpina A4 spec (+/-160bhp). I am running the standard airfilter housing but with K&N Filter cartridges in both ends. Whilst fiddling with the car the other night, trying to get it to run past 4,500rpm under load, it struck me that the stock filter housing may not be sufficient for a 23% increase in power.

What I have thought of doing is taking the end caps off and leaving the K&N's exposed. This will definitely allow more air in, but won't look as neat.

Anyone have an opinion on this?

[Guest Anonymous]

Alpina A4 has ITB's, how doe the stock tii air filter fit to that?

But, I don't think you would see any improvement by just opening them up. You would just suck in more hot air.

Flow is not your biggest problem, hot engine air is. I think CAI would help you much more than opening the end caps.

[Cyclone101]

trying to get it to run past 4,500rpm under load

A stock tii can get past 4,500 easily, and a tuned one would do it even easier. If it struggles, then I suspect you have another problem (eg. fueling/timing)

Remember, your still pumping the same amount of air as a stock tii and only more when you rev higher. So you should be able to easily rev to 6000rpm at least with the stock air box.

Regards

Jacques

[classicman]

Alpina A4 has ITB's, how doe the stock tii air filter fit to that?

But, I don't think you would see any improvement by just opening them up. You would just suck in more hot air.

Flow is not your biggest problem, hot engine air is. I think CAI would help you much more than opening the end caps.

The A4 doesn't run ITB's, the A4/s does.

[classicman]

trying to get it to run past 4,500rpm under load

A stock tii can get past 4,500 easily, and a tuned one would do it even easier. If it struggles, then I suspect you have another problem (eg. fueling/timing)

Remember, your still pumping the same amount of air as a stock tii and only more when you rev higher. So you should be able to easily rev to 6000rpm at least with the stock air box.

Regards

Jacques

Hey Jacques.

I'm 100% certain of the timing and spark supply etc. I'm still working on the fuel supply though and that is where I was also looking at the air supply. More fuel (A4 Kugelfisher pump) would also need more air. My CO reading is already over 5% at 4,000rpm and my fuel pressure reading is in spec (albeit at the lower end). I'm going to richen the mixture at the "verboten screw" and see if it makes a difference. I'm also going to try without the airbox as well, to see if this makes a difference.

[c.d.iesel]

toss those k&n filters into the neighbors pool before

they cover it up for the winter

install STOCK paper filters in the tii can (really)

look to the basics for your running out of uumph

at the upper rpm range...... linkage, fuel pressure,

fuel pump delivery volume test, timing,

cam timing, injection pump timing.........

....or is winter ending there and yer entering Spring now ?

[Cyclone101]

Hey Jacques.

I'm 100% certain of the timing and spark supply etc. I'm still working on the fuel supply though and that is where I was also looking at the air supply. More fuel (A4 Kugelfisher pump) would also need more air. My CO reading is already over 5% at 4,000rpm and my fuel pressure reading is in spec (albeit at the lower end). I'm going to richen the mixture at the "verboten screw" and see if it makes a difference. I'm also going to try without the airbox as well, to see if this makes a difference.

Yes, you would have slightly more air flow, with bigger valves, port/polish, longer duration etc. but not nearly enough to bog your car down a 4500.

Remove you airbox first, it easy enough, and if the problem still persists then look to other places.

But shouldn't you be very rich if your air is restricted at your intake??

Regards

Jacques

[classicman]

toss those k&n filters into the neighbors pool before

they cover it up for the winter

install STOCK paper filters in the tii can (really)

look to the basics for your running out of uumph

at the upper rpm range...... linkage, fuel pressure,

fuel pump delivery volume test, timing,

cam timing, injection pump timing.........

....or is winter ending there and yer entering Spring now ?

@ c.d.iesel - It is spring here now :-)

You must be tired of answering my posts by now.......

Fuel pump delivery volume = 1L in 30sec.

Fuel pump pressure = 22PSI at Cold start valve (Bottom of spec)

Linkages are correct length.

Timing correct - half the ball on flywheel at 2,400rpm

Cam timing is correct

Injection pump timing is correct

It's not even that it just runs out of uumph, it just dies and then gives a bit of a backfire. Even at lower revs if I floor it, same thing, its like the engine dies. If I rev the car at standstill, it revs up, but pops / crackles on the backfire. I had it set much richer at one stage, and it didn't do this but emitted black smoke. I didn't try and take it for a drive then, but should have in hindsight. To compensate, I leaned off on the verboten screw. Maybe I leaned off to much. I'm going to forget about setting the CO for now and see if I can just get it running better by richening up first.

[jgerock]

Article courtesy of photographer Klaus Schnitzer in the December 1982 Roundel (using his modified 72tii).

[BillWilliams]

both the Alpina A4 and A4s are ITB set-ups. The A3 is the Alpina carb setup.

[Cyclone101]

both the Alpina A4 and A4s are ITB set-ups. The A3 is the Alpina carb setup.

This is what I thought as well, was starting to doubt myself. lol

[PaulTWinterton]

Fuel Pump pressure at cold start is low, by any tests I've done on tii's. S/B 28.5psi

This is pointing to fuel tank inlet filter at the bottom of the sending unit.

If it is very clogged it will:

1. reduce pressure at the cold start (your measurement)

2. stall out at high load or high rpm.

Worth a shot to check. I had the same exact symptoms.

Good luck.

[williamggruff]

If fuel pressure is low, it's possible your pressure regulator on the back of the kfish is weak. We had this issue recently on our Lemons tii. the car would have good fuel pressure (30 psi at the front of the kfish) until it got up to operating temp, at which point the pressure would drop precipitously. It appears the regulator spring is a bit mangled, and the valve gets stuck open, dropping the pressure in the kfish and causing a lean condition. We were able to temporarily address the problem by sealing off the return line, which kept the fuel pressure at 30+ psi, and eliminated our lean condition. Of course, it's killing the fuel pump, and probably damaging the seals in the kfish, but that's Lemons for you.

[jgerock]

If fuel pressure is low, it's possible your pressure regulator on the back of the kfish is weak. We had this issue recently on our Lemons tii. the car would have good fuel pressure (30 psi at the front of the kfish) until it got up to operating temp, at which point the pressure would drop precipitously. It appears the regulator spring is a bit mangled, and the valve gets stuck open, dropping the pressure in the kfish and causing a lean condition. We were able to temporarily address the problem by sealing off the return line, which kept the fuel pressure at 30+ psi, and eliminated our lean condition. Of course, it's killing the fuel pump, and probably damaging the seals in the kfish, but that's Lemons for you.

Weak - or just clogged with gunk? The spring is tiny inside this valve and is difficult to get back in with the piston and circlip.