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

On my old engine, I had a pair of schrick 276's (old spec I think as they were 10.8mm lift whereas they are more than that these days) - that ran fine on lumenition ECU on a std plenum, idled sound, plenty torque etc. They would not run with a std digi ECU, total pants. This was a 2L with a brian ricketts head and this made a genuine 180hp (pre throttle bodies).

As soon as you fit TB's, the world is your oyster - matching CR to cam is the key.

 

Been looking at the schrick 260/260 timing figs.

Although they are quoted @ 0.1mm valve lift you can do some rough calculations to show @ 1.0mm valve lift where the valves are off their seat and flowing.

It appears that they actually have negative overlap of roughly 8 degrees so i presume thats why they work well... no chance for A/F mixture to run straight in and out of the cylinder and mess with the lambda.

Basically, there is less valve opening and cylinder flow occuring around TDC. They instead work further from BDC... with the the inlet closing about 3 degrees more ABDC, and the exhaust opening 4 degrees more before.

I was wondering therefore, if it was worth retarding my inlet cam.... maybe to 112 degrees peak lift ... which would move inlet opening to 2 degrees after TDC and thus give myself 1 degree of negative overlap. Would theoretically give a tad more top end and lose a bit of low end.... but that would hopefully be offset by the fact that the ECU wouldn't be ****ing out fuel in that region.

Maybe worth a try?

Tried to estimate glens combination too... seems his works because he only has 1 more degree overlap than standard.... and as there is no increased lift on the exhaust side @ TDC A/F can't really escape...

his inlet fills to around 7 degrees After BDC than standard which is probably aided by his headwork and manifold porting.

 

okay... had 1 power run... was down 8 bhp and 8 ft lbs so the old girl isn't happy.

checked timing today with the dial gauge again and the exhaust cam is well out...

I can't understand how it is out so much though, as the cam pulley fits into the machined slot on the cam and the marks on the pulley line upto the marks on the rocker cover and cylinder head when it is at TDC... exactly.

so if i set it up to the correct peak lift angle by adjusting the cambelt this will mean these marks are miles off....

im too confused to work out why so would really appreciate some help.

 

Well did just that... set the exhaust cam up exactly so the cam pulley marks dont line up.....

it was retarded about 8 degrees so advanced it and re-adjusted the inlet cam on the vernier. ..

and.... runs really well. Still slightly burbly on idle but you can ease away very smoothly without having to ride the clutch and there is no un burnt fuel.

In fact... took it for a 10 mile drive and got 35-37 mpg! was even over 40 at one point......

Not going to estimate gains as apparently i was miles wrong last time im just pleased that it drives normally again TBH

Still don't understand why the standard pulley marks didn't line up though...

 

by rights, they should - the keyways should be cut in the right place - I think you have done everything right but it just goes to show, you have to go back and do it the proper way

on an engine with both cam pulleys on the belt end, its much easier

hope it come out well on the rollers

 

Finally had a let up in the harvest so managed to get back on the dyno.



Pleased with the results... kind of what i was expecting

Peak power was 160.1 @ the wheels, graph shows 159 after smoothing.

Thats about 5 bhp gain, with 6 ft lbs torque.

I wasn't really after peak gains though, and its nice to see the sharp rises after 5000 rpm, extending the power/ torque band.

i also now have a dollop of 8v torque @ 2800-4500 rpm which makes cruising fun!

in fact, i have more torque @ 3800 rpm than 5000 rpm! Still Want to try and lift the curve up a bit in the middle with some specialist mapping...we reckon the ignition isn't advanced enough. matt from QEP reckons the new style unichips could do the job so will have to see. If i succeed then it could pull like a train all the way from 3500 rpm...

Also, my inlet cam is still slightly advanced as i got fed up trying to adjust the internal vernier, so i could potentially retard it a bit for more top end, but i don't really want to lose my bottom end bulge now!

All in all not bad i reckon.

 

Yeah you need to investigate the cause of the 'hole' in the center and rectify. If sorted that will pull well strong. Depending on ECU access you may be able to refine the whole curve.
This is why I hate chips burnt on a desk without validation on custom hardware!

 

160 @ the wheels, that's good going! almost 200 @ the fly right? as most 02A gearboxs seem to eat up 35-50 hp.

 

Very different results to me..
My ABF shows approx 20 BHP less at the wheels average, but with around 30 lb-ft more peak torque average.

I must admit, I would have expected a bit more of a gain from a pair of cams.

 

think transmission losses aren't that high.... reckon about 20-25 hp. its probably about 180.. seems about right on the road. Anyway... its a chassis dyno so pointless speculating flywheel figures

This is a Mustang chassis dyno which uses an Inertia load as well as an eddycurrent brake load to simulate the "actual" load (combined aerodynamic plus rolling frictional load) that the vehicle would experience when in motion... so its shows less transmission losses than a run down dyno.

The key thing about it is its repeatability which is excellent as you would expect for 115k worth of dyno... this makes it great for a modification tool.. not sure you can compare dynos.

The gains are what i was expecting, they aren't very fruity compared with standard, with just a little more lift... hopefully mapping will get more out of them.

132 ft lbs of torque is a wheel figure too... not sure what it is at the fly... probably about 150.

 

Had its MOT today and....

Passed! Not even an advisory! Thats the 3rd year in a row....these cars are bombproof! CO2 emissions were borderline on idle... absolutley fine on fast idle.

Still want to map the cams in properly to get the most out of them and lift the midrange and rev limit. Whats the safest the ABF can rev too... bearing in mind it has high lift cams and lightweight lifters?

Is is possible to custom map DIGI 3? was looking at Piggyback Dastek Unichips but havn't heard much about them

Would it be cost effective to go stand alone?

Cheers

Ben

 

I use 7300 RPM as the limiter.

Yeah, you can custom map Digifant 3.2...mine is!
I think R Tech can do it. AmD used to be able to...not sure now though.

Or try Megasquirt, if you want to play about?
You can always have a play with my plug and play MS at some point if you want.

 

Cheers Glen. Think you might be a little to far away up in scotland though!

What are R tech like?

I should have a 50% discount at custom-code as there was on offer on when i had my stage 1 chip. Not sure if they can do custom digi remapping though.

Does it involve writing a custom map for the car, programming an EPROM chip then soldering it onto the ECU?

7300 rpm would be ideal to try and solve the long ratios, as third gear still falls out side the power band

 

I may be...but my MS isn't...it's down in Englandshire in safe hands at the moment!

No idea...but they can custom map.

Mine has a carrier board fitted in place of the EEPROM and you plug an Emulator into that, map it, burn it to the EPROM and push it into the carrier...no soldering involved.
That was AmD/Star's way...not sure how R Tech will do it.

I'm using lightweight lifters, std valve springs and 268 cams, light flywheel and new std flywheel bolts (now uprated...but wasn't) and it's happy at 7200-7300. My peak power is 69xx so just a few 100s higher.

Are you still using the standard 3.67 FD?
If so....change it!

 

Yeah. You have metioned it before. I know nothing about gearboxes though and wasn't sure how to get to a 3.94 FD... isn't it using the passat gearbox?

eibach ARB's are my priority though, as is sorting out the flat spot between 3-5k.

I might have to speak to r tech as they are near my bro's uni so could stop in their next time i visit.

I also want to enquire about the dastek unichip, as apparently they could be able to isolate and iron out the MAP pulsing signals from ABF's on cam's.... and use throttle postion to create a stable idle.

Worth looking at as it could free up camshaft options on Digi run ABF's.

where about in englandshire is your megasquirt?

 

Londonshire....ish.

 

Hmm... not far from me. Wouldn't have a clue what to do with it though!

quite tempted by gearboxes now. AGC 02a anygood? ratios look pretty hot for a 16v....

 

AGC is used in the corrado KR 16v and passat, same ratios as mk2 020 box IIRC, i.e. lowest of all the 16v engines, 2L 9A engines are slightly longer legged and the mk3 16v box is the longest of all of them.

 

02A AYH from a Passat if you can get your hands on one.

 

Standard CDA/DPA 16v ratios are pretty good...if the 'box needs a freshen up anyway, just drop a 3.94 or 4.2 FD in there...3.94 is good...4.2 is epic!
It'll pull to the fuel cut in top on a 4.2, on 215/40/16s - geared at around 19.5MPH/1000RPM in top.

What's the AYH got fitted?
How do the ratios compare to the CDA/DPA?