MK3 16v ABF - Dyno Results before and after 261 deg Catcams

AGC--AYK--CDA
3.78 3.78 3.30
2.11 2.12 1.94
1.35 1.43 1.31
0.97 1.03 1.03
0.80 0.84 0.84

AYK is same as AYH AFAIK

How is with top on AGC is it runing at to high RPM ?? On 215/40 16 .?

 

cheers for sending me that G60 DUB very useful

whats the effect of just dropping a 3.94 FD into my box then?

Main problem is with 3rd gear falling out of the power band

 

True the ratios are the same but the AYK only has a 3.68 final drive whereas the AYH has a 3.94.

There are plenty Passat boxes with the 4.2 final drive (CJA/CRU) although I recon long journeys with a 4.2 (unless it's on a flatbed) would be out of the question.

EDIT: There are also lots of Passat 02As that have a 3.94 final drive but a **** set of gears: CHA, CEY, CEX, AYP, AYM, AGC, ATW,ASB, ATX, AFF & CAT. You could use the FD & output shaft from those and choose your gears from another 02A box or as Glenn has done keep your 16V ratios.

I'll upload the ratio sheet to photobucket in a mo:



^^ Sorry I couldn't fit in the bit that shows what engines were fitted.

...and yes I spent hours and hours trawling though ETKA. Sad I know.

 

Nah...it's fine at 80MPH and below is it's 'off cam' below 4000 RPM.
Sitting at 4000 RPM shouldn't be a problem for anyone.

VR6T has built a hybrid 'box for his Mk3 G60T and used a mix and match of gears...I never bothered and stuck with std 16v gears...just changed the FD.

The differences are slight...I guess you could try to get a close-ish 1-4 with an overdrive 5th...but I'm happy with a close-ish 1-5 and 5th at around 20MPH/1000RPM in top...the figure i've always founf pretty good for fast road gearboxes for all-round use.

 

Thats good to know Glenn; I had always thought a 4.2 would be too buzzy at motorway speeds hence me going for the 3.94 AYH box.

Is the fuel economy using the 3.94 really that much worse than a 3.68 or is it your right foot that guzzels the petrol?

EDIT: Just got 409 miles out of 1 brimmed tank but only because I'm skint - Edinburgh to Whitehills & back.

I hope I'm going to like the short 1st to 3rd but guess it will be a pain on anything other than bone dry tarmac. Still not keen on the huge gap between 3rd & 4th but not much in the way of a shorter 4th in any of the Passat boxes. I wonder if any of the 02J gears fit the 02A shafts?

Anyway I can't really comment much; my box has been sitting in a cardboard box in my bedroom for the last 8 months... Ice ages come and go quicker than my gearbox rebuild. Just needs shimmed and I'm ready to go; unfortunately the diff will have to wait until I'm working offshore.

 

So did I! I actually did it to go up a profile in tyre to try to sort out some of the crashiness...but can't bring myself to change the gearing now. It's too much fun!

It will be worse...but I have heavy feet and getting 20+ MPG is about right...so I can't honestly say what can be achieved if taking it easy...as I don't. The Mk3 is just a toy...

1st is a bit of a none-event...it goes quickly.
I don't mind as mine is a full road car with a full interior...so lardy (like it's owner!).
2nd, 3rd, 4th are great now...5th not noticably different to the 3.94 in all honesty.

Traction less of an issue if you choose to drop a Quaife in there at the same time as you are playing with FDs!

I don't notice a gap from 3rd to 4th now...7200ish in 3rd, drops it onto the cams in 4th, no problem.

Get it done man!

I guess i'm lucky to have a VW MasterTech as a mate...my gearbox practically falls out when he looks at it now...it's been in and out that much!

 

I know I know... Have to have it in before Xmas really or Jan at the very latest as Jan/Feb the house will be getting gutted as I'm moving to Banff or thereabouts.

Gearbox removal is my bane - Normally I can do a clutch swap in about 6 hours. Last time I had the box out to fit a 'Mart' it took me 12 hours in total. I have no idea how it took that long but it did. My story is that I think I was abducted by Aliens.


EDIT: You have a 4.2 now then? Holy moly that will fly.

 

I'm thinkin' 4 every day use AGC and 3.94 FD would be just fine on ABF, with std cam on 215/40 16 setup you are 226 kmh at 6500 rpm I think, but you should get there faster, if you cam the car and able to get it to 7k rpm or so in 5th gear you should see about 244 kmh, pretty good.

 

I'm obviously having a bit of a thick moment here. I cant understand why changing the final drive is making the car any faster. The revs drop to the same rpm at gear changes and only the speed is differant. How is this making the car accelerate quicker?
Too late at night for me and too many drinks obviously.

Paul

 

Paul, To exagerate the effect, imagine that your 2nd gear became 1st, 3rd became 2nd etc. When you set off in 1st (which is 2nd now), the car would accelerate really slowly, you`d always be in too high a gear.

What the FD does is reduce the mph/rpm ratio. in effect making 1st a 0.75, 2nd a 1.5 and so on.

does that make sense? I know what it does, but its hard to describe (or i`m making it hard )

 

No faster Paul, but quicker through the gears as Nige has described.
You can feel the same affects by going back to 195/50/15 or 215/40/16 tyres from 205/40/17s for example...

The downside is that you potentially reduce the top speed...but since a tuned Mk3 16vs will only do around 140MPH genuine anyway, whether you do it at 5000RPM or 7200RPM is immaterial, as by that speed aerodynamica tend to be the limiting factor, rather than power....so in this instance, I haven't found much difference between a 3.67, 3.94 and 4.2 FD...

It just works...

 

Did I say that?
Damn!
Cat's out of the bag now...eh?

 

Which your mate lived down here on south. Then he could look at my VR6 and make the gearbox fall out. It is about time I fitted my clutch and feather weight flywheel

 

A shorter FD and gear set ( bigger number) will increase axle torque with a reduction in rpm. This torque gets to the wheel assembly, where the twist is trasmitted as axial force to pull/push the vehicle. This force will try to accelerate the mass of the vehicle until opposing forces are equal or greater than the generated force.
The rate of acceleration is directly related to the engine torque. This is why gear ratios should be matched to the purpose the vehicle will used and the engine torque curve.

 

It works really well - much better than engine mods actually. If you go too far, the gearing will then limit your top speed - I have this situation now where my car will hit the rev limiter in top gear @ 136mph.

Gearing is a fascinating subject - and for racing can massively affect your lap time - you need the right gears for the critical corners on the track so you are not stuck between gears in the corner. Overlay on this the torque curve for your engine and what gears are actually available - its a great puzzle to solve.

We dont talk about gears and gearing anywhere near enough - they really do affect your speed much more than the kind of engine mods an amateur can do to a valver

 

What gearing are you running Rob?
Tyre size, FD and gearing?

I can't find anything bigger than a 4.2 for the 02A...does such a beast exist?

I think I can just crack 140 MPH (140.4 MPH @ 7200 in top on 215/40/16s, 4.2 FD and a standard CDA/DPA 5th)....also 0-60 is achievable in 2nd (using 7300 RPM) is that's important to anyone...

Sure is...it used to be the easy tweak back in the Fiesta XR2/Nova SR days...now people just seem to ignore it...shame really. It makes the car so much 'nicer' to drive hard.

Here, here, Rob.

Dropping a 3.94 and light flywheel into a 16v Mk3 is like adding 30-40 BHP (if not more).
People chase big numbers and will spend 2000-3000 doing it...where spending half of that gets you a low FD, gearbox rebuild with a Quaife and a light Flywheel...leaving you with a much faster car point to point.

 

Agree with the whole gearing subject.

Changing from the standard 3.67 to a 4.25 tranformed my car into a beast! lol. The 117mph top speed is a bit limiting though.

Thing is that most gear sets/mods cost serious money so end up out of reach for the budget tweeker. But maybe not as much as some moderate engine mods I guess.

Gurds

 

Azur, looking through your thread, has there been any work done to the head?

Gurds

 

The head hasn't had any work on it fella

Just put the cams in with some lightweight lifters.

I don't think they are lairy enough to be limited by the flow characteristics. They have about 4-5% more lift than standard and i got a 4-5% gain. It was the lobe profile and rate of opening i was interested in to try and get the valves opening quicker to where the 16v heads flow best.

when I get them properly mapped it will be interesting to see if i can lift the middle of the curve (3-5k) or whether it is being kept flat by the standard head.

Will consider headwork in the future but my ABS has just gone tits up and my Msc is draining all my money!

Can i buy a 3.94 FD from VW for a passat box then? What else would i need?