Cam advice (4 cyl)

[scuzzyGTV]

Ok, so start with the sob story because I'm feeling sorry for myself  (not too bad though!)

So over the past 6 months I've been jointly prepping my gtv for some hillclimb & track work, this has included an engine rebuild with 10.4:1 pistons, some 10.5mm/315deg. cams (2nd hand, no spec sheet = stupid newbie!) & a wolf 3d v4 ecu (be ware of possible issues). long story short I've had most of the work done by a mechanic, as I don't have the time to do a lot of it myself, and today we visited the dyno. In Hobart there are about 4 dyno's and my tuner works on about half of the Targa Wrest Point field, so I have confidence in his tuning ability, even though he's not familiar with alfa's.

It returned a (not worth spending any money) 60 rwkw & 110 Nm  , where it was:
1. hard to get close to an idle as the overlap removes all vacuum at low revs, stalls below 1500 rpm
2. problems with the ecu (apparently some wolf's work really well, others less so: mine is the latter!)

He has suggested that I put the standard cams back in and try again (10520's), nice in theory, but we got the head machined so fit the higher lift cams, are there issues with this? Could I put in a set of 48's and have it work a bit better?

The other option that I'm thinking is to start playing with the settings of the cams, to see if i can reduce overlap a bit to get some purposeful power.

Or is it time to give Vin Sharp another call and save for some of his goodies. 

Any advice is welcomed.

Thanks

Scott.

[BradGTV]

wow, i thought your power goals were a little bit out of reach but not that much 
im thinking something must be very wrong as thats less than standard power isnt it?
are you running a distributer or coil pack and trigger wheel ignition?

[Duk]

He has suggested that I put the standard cams back in and try again (10520's), nice in theory, but we got the head machined so fit the higher lift cams, are there issues with this? Could I put in a set of 48's and have it work a bit better?

There shouldn't be any problems, the machining to fit mad camshafts is typically for clearance of the larger cam lobes.

Can the wolf be configured to use the TPS as primary load sensing? That should help with low rev tunability and stability.

What sort in intake system are you using?

Were the cams supplied with any recommended settings? If so, did the mechanic set up the cams to spec?

[Jekyll and Hyde]

Have you done any porting on the head, bigger valves etc?  If the 315deg means 315 degrees duration, that sounds like full race cams to me.  Would need a lot of head work to get the best out of them, as well as a fair few revs, and the chances of a decent idle using a single butterfly are pretty damn low, even if you do run off TPS rather than MAP.  Doesn't really make a lot of difference how you time the cams, with that sort of duration you'll have a lot of overlap no matter what you do.  You could go back to carbies to smooth the idle, or change to individual throttles...

However, I'm guessing the head is fairly standard, which would make either of those changes fairly pointless, as it simply won't flow enough to allow the cams to reach their potential.  Indeed, the cams may even be losing you power (and particularly driveability) instead of making any gains.

Throwing the standard cams back in would definitely be the cheapest option, and shouldn't lose you any power (but will gain driveability).  My suspicion (without knowing how your dyno reads in relevance to any others, they're all different) is that you might actually gain some power given your comp ratio - you almost certainly will gain low to mid range torque.  If you have some 10548s lying around, they'd be a nice little improvement, but if all you have is the 10520s, use them - at least you can set them up correctly, and then have it dynoed to make sure the ecu and the rest of your EFI system is working correctly.  Then you can either modify the head to give the airflow the cams want, or get some other cams that fall into the 'fast road' category rather than the 'race' category.

Of course, if you have much bigger valves and some serious porting, disregard most of the above (with exception to the part about idling).  If this is the case, you need to look into cam timing, fuelling, check all your setup. 

[scuzzyGTV]

Thanks guys,

It is currently set to run TPS as load, and at this point there isn't much done re head work (I was planning on doing this on the spare head).

The ignition is using a (new) distributor as crank angle sensor, and coil packs, and we're running 260cc injectors.

The cams are currently set up as per original, so nothing has really been done to try and find a sweet spot. But given Jekll & Hyde's comments, I dare say they wont in the current setup.

Ok, so plan's looking liek this:
Get car registered!
Pop standard cams back in to see what happens. If it runs better, get re mapped accordingly.

Ultimatley, I'll work the spare head with these cams, doing some flow work, and refine the setup.

[Storm_X]

Trial and Error.

I would just go to standard cams and see what happens. Also would 260cc injectors on that engine be to small ??

Ill see when i can get my car on dyno and tell you standard power.

[ANG156]

Also would 260cc injectors on that engine be to small

my brothers Giulietta runs 196cc injectors.

[Storm_X]

Also would 260cc injectors on that engine be to small

my brothers Giulietta runs 196cc injectors.

I dont know anything about fuel injection, but i spend to much time helping frinds do work on there supras and silvias etc and there injectors are much larger.

How big are the injectors of a v6 commodore ?

[BradGTV]

im pretty sure ecotec is about 186 cc , ill be running 252cc saab turbo injectors on mine

[vin sharp]

315deg is way too much cam timing for 10.4:1 (used only 308deg for full race nord engine giving 223bhp on Tilly's dyno), especially if you also want broad range drivability. Suggest you go back to std cams if you have them at hand and see what that does: at least it may point you towards problems in other areas with managment etc, as it will eliminate the excessive duration issue from the equation. If then you are still below your needs/expectations from the engine, you can think about more suitable cams/bigger valves etc. (have everything from 10548 upwards).
Cheers,
Vin

[scuzzyGTV]

Thanks Vin
Will definently give you a call once issue(s?) is discovered to discuss possible options.
I'll drop in the 10520's in the next couple of weeks, then report back.
Scott.

[scuzzyGTV]

so 10520's are back in and man has it made a difference. even without another dyno session, just some basic fuelling changes, it goes like it should!
retarding the bigger cams didn't work too well, it improved the vacuum, but not nearly enough to get any benefits.

so next step is to stop being an idiot and buying stuff that will never work save some $$$ and upgrade to something with more lift & duration, but still within the motor's limits.

[BradGTV]

good to hear its running well, im debating whether to inject mine or keep it on carbs, i think i might go with some gsxr throttle bodies or spica ones. do you prefer the engine injected or with the carbies?

[scuzzyGTV]

Brad, I haven't really had a chance to take it for a proper drive yet  but it does seem to be a reasonable system. However I do miss the induction noise of the carbs, but now it's tuned better the exhaust note is hitting the spot, so can't complain too much.
I suppose, as always, you need to decide what you're planning on using the car for, because it's not a (relitively speaking) cheap thing to do. Using some independant throttle bodies, would be good too. If you are using it on road, and in largely unregulated (as far as modifications go) events, like I will, it's not a bad way to get some extra control of fuel & timing.
If you do convert to TB's, then do make sure you keep us up to date.
Scott.

[djm411]

HI Scuzzy,
just out of curiosity where did these cams come from?
Also a general question, what are you intending to rev this engine to? this parameter actually makes a big difference on the cam design and timing.