V6 24V camshaft saga

scociu
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V6 24V camshaft saga

Post by scociu » Wed Aug 02, 2017 11:51 pm

Recently ran into a bit of trouble trying to get some more HP out of my 3.2 engine.
I tried fitting a set of regrind cams and, with the timing set on factory marks or even using the original GTA cam locks, the ECU complained about crank-cam phase being out of sync and ran in limp mode and didn't rev above 3500 rpm (i guess it fired the sparks on both compression and exhaust strokes since it didn't know where it was).

Here is what I did, in chronological order:

1. Removed OEM GTA cams, fitted the regrind.
- engine missfired and detonated when started
- after checking and cleaning all the connectors it ran fine
- threw phase error (P0340) after 1500 rpm when hot

2. Re-checked and redone timing
- found bank 1 exhaust cam 1-2 degrees retarded
- adjusted it to be on spot
- engine ran worse, in limp mode, phase error always present. Didn't rev above 3500 rpm.

3. Sensor and ECU check
- tried different cam phase sensor. the same
- tried different ECU. the same
- measured sensor output with an oscilloscope, signal shape was ok
- couldn't source a two input oscilloscope to check its phase against the rpm signal
- the only documentation i could find around how the 60-2 trigger should work was from the 12V engine. This suggested that the cam sensor should fire 120 degrees BTDC.

4. Tried to align the exhaust cam so the sensor fires 120 degrees before TDC
- to make this work i had to retard camshafts by around 3-4 cam degrees.
- i basically redid the timing with engine at 6-8 degrees ATDC
- car ran "fine" after this, no errors
- the power seems to be shifted upper in the rev range, which is expected
- tomorrow i will put it on dyno. with OEM cams it made 240 HP at the wheels. if it doesn't make at least that, i will switch back to the original camshafts.

I don't understand what could possibly be wrong when the timing is set at 0. The regrind cams are based on 3.0 24V, I can't imagine any scenario where they shouldn't work with factory timing. The only remaining thing to do is to measure the angle between the factory mark and the cam position pickup knob then compare this to the original GTA cam. But how could they be different?

Any thoughts? Thanks in advance.
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156 GTA - Intrax 1K2 ARC - Q2 - AP Racing Radi-CAL PRO5000R 356mm - Whiteline ARBs - CF2 headers - ACT Carbon Plenum - Ferrari 360 TB - Sabelt GT-200
Jim K
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Re: V6 24V camshaft saga

Post by Jim K » Fri Aug 04, 2017 11:35 pm

Last things first. Go find another dyno and re-measure. GTA engines have consistently produced 225-229 wheel hp. Alfa has been consistently optimistic about their power figures ...adding VAT since the early '60's! :lol: You'll find interesting reading here: http://rototest-research.eu/popup/perfo ... artsID=216
Now the cams... When cams are reground -no matter who does them- NOBODY checks the original timing mark. They 'try' to grind evenly on both sides of the original lobe, relying 100% on visual confirmation of this! There is no other process used where the lobe is centered for grinding, period! Therefore, variations of 3-4* are entirely common. After this first mistake (or blatant inaccuracy) the remaining lobes are surely ground at proper 120* intervals related to the first one. In other words, they are ok between them but not with the timing mark scribed in the rear end of each cam or the cam phase peg. This said, the only proper way to set cams is to accurately graph the lobes and determine cam lift at the desired timing point. Some prefer to adjust intake and exhaust cams at XX mm lift for each at overlap TDC, others prefer to time at max lobe lift at some value chosen between 102-112*ATDC for intake and BTDC for exhaust. IF you know what you are doing and have the proper dial indicators/protractors available, both methods are correct. Oh...don't rely on the front pulley TDC notch! Use a proper gauge instead!
Now if after all this the idiot lights still come on, it probably means that the cam timing peg is nowhere near where it should be. If you are really pissed and determined to correct, you can remove the cam, knock out the peg, make a longer one on a lathe with M5 thread on the back, then make the peg hole into a slot, so you can adjust the radial position of the peg by sliding along the slot and then tightening in place with a small M5 locknut. If all this fails...sell the bugger and buy a BMW M3! They have double Vanos and you won't give a crap about cams anymore!! :lol:

Jim K.
scociu
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Re: V6 24V camshaft saga

Post by scociu » Sat Aug 05, 2017 7:35 am

Thanks, Jim!

About the dyno: I trust the dyno I use as being reliable, it's a mustang chassis dyno I used several times in the past. I don't look at the absolute value anyway, just at the difference between measurements so I cannot speak about how close these engines are to the declared power figures. I had 210whp before any modifications, went to 240whp after full decat, enlarged carbon plenum with trumpets, larger throttle body and remap. Keep in mind that the rototest in your link does not account for losses in the tyre so it will measure slightly higher numbers than a "regular" dyno.

About the cams: Thanks a bunch for clarifying the regrind process, this clears a whole lot of confusion that was bugging me around why the car refused to work when timing was set by the marks. I am surprised though that a lot of people recommend setting them by the factory marks.

A follow-up question:
1. Are all 4 regrind cams guaranteed to be in sync? Or is it better to time(either by lift at TDC or by max lift) each one individually as the 3-4 degrees variations you mention could be different on each cam? I set TDC using a dial gauge and degree wheel, not by marks.
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Re: V6 24V camshaft saga

Post by 75evo » Sat Aug 05, 2017 12:44 pm

Roto-test is a hub dyno like the dynapak. So there should be no frictional loss due to tires and roller contact. Dyno numbers vary too much. Here 230 bhp wrxs only make 180+ on a Mustang dyno. What does that mean to you? Absolutely nothing! The Mustang dyno here may not even be calibrated properly, or maybe the mustang dyno you use is not calibrated properly! 240 bhp USA spec M3s only have 200 whp, so it's not a big surprise for the GTA to have about 190-210 whp. Again, means nothing to me.

And my modified 75 3.0 12V makes what... 183 fly wheel bhp if'm lucky? Maybe only puts out 150 whp on a good day?

Forget the dyno, here's proof:

https://youtu.be/wqnNXbAXLuc

https://youtu.be/7hGnOqT0nME

Passing M3s since 2011 :)

Dyno is only good for before and after comparison on the same car and on the same dyno. So you got 30 whp, which is impressive!

But Jim's statement got me a little worried, the means the timing mark is useless for most regrounds. I have to use the dial indicator now. Luckily my 3.2 is not in the 75 yet!
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Re: V6 24V camshaft saga

Post by Jim K » Sat Aug 05, 2017 10:13 pm

Each cam must be set separately. Anyway, when you have the TDC gauge in, the two cams on overlap and the two dial indicators, you can do cams 1 and 2 in one step and then repeat for cams 3 and 4. This is quicker than doing one cam at a time at max lift.
The regrind 'mistake' is valid for every cam put on the machine but may vary in degrees from ane cam to another. There is no easy way or provision to 'zero' the cam on its marks and then grind.

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Re: V6 24V camshaft saga

Post by Maurizio » Thu Aug 17, 2017 11:08 am

Jim K wrote:If all this fails...sell the bugger and buy a BMW M3! They have double Vanos and you won't give a crap about cams anymore!! :lol:

Jim K.
they have other crap/shitty design to loose your hair on.... enough to wrench on and rust is also an issue :roll: :twisted: :lol:
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Re: V6 24V camshaft saga

Post by 75evo » Thu Aug 17, 2017 9:22 pm

Let's all switchover to VTEC
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Re: V6 24V camshaft saga

Post by KevinR » Tue Aug 22, 2017 1:00 pm

I'm surprised my car runs as I set my Van der Linde regrinds on the marks . So now I am actually thinking how much more power and efficiency I can get if I do this properly after reading the above - which makes total sense . I have remarked my pulley with tdc cuts on it .
I need vernier pulleys !
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Re: V6 24V camshaft saga

Post by Jim K » Wed Aug 23, 2017 5:32 am

Oh, it will run even if you're ±10* off, but the question is where will it give the fullest power curve? That, unfortunately, is a question answered only by trying out different settings. Not too hard to do with the 24v car on the rollers, playing with adjustable cam wheels.

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Re: V6 24V camshaft saga

Post by Murray » Wed Aug 23, 2017 2:35 pm

Power, power, power that's all you care about eh Jim.Sick - I love it.Yeah cam timing is a bit of science and a bit of black magic and you're the master.Equally fun and somewhat easier is ignition curve monkeying. You can get some surprising results particularly playing with the big fat torque curve the Busso produces.
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Re: V6 24V camshaft saga

Post by Jim K » Wed Aug 23, 2017 6:42 pm

No master, as I haven't even tried different settings on mine! I did go to one dyno for a remap a few weeks ago and will go to another for the same job next month -just want to see what the differences can be as I hear numbers flying around. I am also looking for a bog-stock gta for a baseline measurement on the same dyno, but its hard to find someone without even an air filter swap -from the few cars we have here. From what I see, I may reluctantly have to change to the fwd (chrome pipes) plenum setup, vs my preferred rwd symmetrical-looking one. No numbers now, all in good time. But so far, I am amazed at people claiming even more than 300hp from 3.2's with just a remap, air filter and better exhaust -no engine work at all.
The graph is not bad, but no numbers for now! Cams are at factory marks, as imprecise that can be! :mrgreen:
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Re: V6 24V camshaft saga

Post by 75evo » Wed Aug 23, 2017 9:36 pm

Why do you need to swap the plenum setup? Low torque?

Actually didn't Marc Van Worserman (sp?) dyno his SZ with a stock 3.2 and aftermarket ecu at 300 bhp?
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Re: V6 24V camshaft saga

Post by Jim K » Wed Aug 23, 2017 10:56 pm

That's exactly what I'm saying regarding power. Measurements don't mean $hit if you don't have a baseline figure for the same engine in stock form on the same dyno, or if you're doing a before/after mods measurement. I can go to 10 different dynos and get 10 different readings from 230 all the way to 300hp. Does the highest one satisfy our ego? Maybe, but without a stock engine comparison figure on the same dyno, its just a number floating in air -hot air at that!
If the 3.2 has 245-250hp and it went to 300 with 'just a remap', then Alfa and Bosch engineers are a bunch of incompetent assholes for missing out on 50-odd horses.... What do YOU think? :roll:
Check this out for the 3.2 and weep: http://rototest-research.eu/popup/perfo ... artsID=216 and here for the 3liter 24v: http://rototest-research.eu/popup/perfo ... artsID=483
These guys are as serious as you can get in the power measurement industry and would rather speak of wheel power rather than engine power. All rolling road dynos measure wheel power by virtue of either load cells or acceleration of a precisely known mass (rollers). From then on, they each have their own software factoring in who-knows-what, to give you a 'flywheel' figure. I've heard factors from 5% all the way to 23%... I urge you all to do some research on the subject of dyno losses, its really a fun past-time! :D

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Re: V6 24V camshaft saga

Post by scociu » Fri Aug 25, 2017 3:45 am

An update from my part. Put the car on the dyno and ended up with 230 whp. So I lost 10 whp after changing to regrind cams timed relative to the marks and not by setting lift vs TDC.

To sum it up, since there was a lot of discussion above around dyno figures:
- Stock 3.2, no mods: 210 whp
- After full decat, enlarged carbon plenum with trumpets, larger throttle body and remap : 240 whp
- After changing cams to regrind profile: 230 whp
Ambient and intake temperatures in the same ballpark for all runs.

Keep in mind that this is a mustang chassis dyno known for showing low (or i guess realistic) numbers compared to other dyno types.

I will most likely leave it like this for this year and redo the timing in the winter. Spent more time than I wanted to on changing cams already. :?
156 GTA - Intrax 1K2 ARC - Q2 - AP Racing Radi-CAL PRO5000R 356mm - Whiteline ARBs - CF2 headers - ACT Carbon Plenum - Ferrari 360 TB - Sabelt GT-200
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Re: V6 24V camshaft saga

Post by Jim K » Fri Aug 25, 2017 5:43 am

You lost 10hp with bigger cams? :shock:

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