what cams for S/C ?

rik1083

spin the sc up?
putting a 3.1 on mine as soon as new engine is ready

techieboy

I've got a 2.9" pulley rolling around in the boot of the VX now. Only problem (for me at least) is that it requires new LEH VXR injectors to fuel it and unfortunately Courtenay's have had less success mapping the OE ECU for these injectors. Might mean going from my nigh on perfect fuelling to a less accurate and richer map. If the Z20LET ECU swap happens, they'll have no problem mapping it on the Motronic, it's just this poxy Delphi that causes so many of the headaches.

winstar

techieboy said:

rik1083 said:
sucky..

Yep. Feel a bit like that for the whole low compression exercise as well. 20bhp down on my initial standard compression conversion. Might mean I've got a rock solid base for a Harrop but not so good in the meantime. 🙁

I have to say I've always agreed with alanoo that the compression ratio should be kept up if your using the M62 not the Harrop, but the problem is that the pistons aren't easily, or cheaply available.

I'm considering a SC project engine and wondering about getting the head skimmed to get the CR back up.

exmantaa

rik1083 said:
sucky..
i want some std lsj cams really

LSJ cams are the same profile as our 2,2 cams, only different timing and the 2,2 exh.cam is shorter:
http://gmtunersource.com/media/racertec ... HEET-2.pdf
(I have 2 LSJ camsets, but they are both mounted in complete heads. Also have a new set GMR cams for the LSJ. 😃 (But probably with lifter issues..)
Anybody wants to do some dyno comparison?? :thumbup:

Suitable forged pistons for the 2,2 seem a bit problematic, as I don't fancy 4032 alloy ones for "non-race" use... (temperature expansion => bore gap)
The LSJ runs 9,5 compression and I would not go below that. (With some hotter cams the dynamic compression will also be lowered, therefore that GM racing buildbook used 10.0 pistons.)
Diamond makes 9.5 or 10.0 pistons, but also in 4032. (They do others in 2618)
Anybody know what parts Hitec uses for their builded 2,2 blocks??

exmantaa

rik1083 said:
sucky..
i want some std lsj cams really

=> http://www.cobaltss.net/forums/showthread.php?t=189700 :thumbup:

techieboy

winstar said:

I have to say I've always agreed with alanoo that the compression ratio should be kept up if your using the M62 not the Harrop, but the problem is that the pistons aren't easily, or cheaply available.

I'm considering a SC project engine and wondering about getting the head skimmed to get the CR back up.

Speaking to Chris Randall at Hofmanns the other day, he felt the same. He couldn't understand why we all went lower compression with the M62. They run 11:1 on the supercharged Honda M62 conversions and come out at 300whp. How else can we tackle detonation and having to retard the ignition? All of this stuff is well over my head. :crazy:

exmantaa

Seem to be something with the Ecotecs head/piston design that it can not run such high CR without knock. notsure.gif
Remember reading that Courtenay had to retard ignition on higher boosted M62's sofar that the power went through the exhaust...
Maybe also the reason that US guys have such good results running on E85 fuel=> No knock, no retarding, lots of power. 😃

techieboy

Yep, Courtenay's certainly had to retard my ignition a fair way on the original standard compression conversion. The soon as I went to the low compression setup, they cancelled the retard and applied some extra advance. Is this something a decent ECU would help - giving more finite control of the ignition timing?

Has anyone tried the standard Piper regrind cams with a supercharger? Somebody has just offered me a pair for £150 but won't bother if they don't bring anything to the party or are pain in the proverbial to map again, like the blower cams.

winstar

techieboy said:

winstar said:

I have to say I've always agreed with alanoo that the compression ratio should be kept up if your using the M62 not the Harrop, but the problem is that the pistons aren't easily, or cheaply available.

I'm considering a SC project engine and wondering about getting the head skimmed to get the CR back up.

Speaking to Chris Randall at Hofmanns the other day, he felt the same. He couldn't understand why we all went lower compression with the M62. They run 11:1 on the supercharged Honda M62 conversions and come out at 300whp. How else can we tackle detonation and having to retard the ignition? All of this stuff is well over my head. :crazy:

Yes but the IIRC the honda has variable valve timing and uses a stand alone ecu that they can fully map allowing them map to a high compression and boost.

exmantaa

winstar said:

techieboy said:

winstar said:

I have to say I've always agreed with alanoo that the compression ratio should be kept up if your using the M62 not the Harrop, but the problem is that the pistons aren't easily, or cheaply available.

I'm considering a SC project engine and wondering about getting the head skimmed to get the CR back up.

Speaking to Chris Randall at Hofmanns the other day, he felt the same. He couldn't understand why we all went lower compression with the M62. They run 11:1 on the supercharged Honda M62 conversions and come out at 300whp. How else can we tackle detonation and having to retard the ignition? All of this stuff is well over my head. :crazy:

Yes but the IIRC the honda has variable valve timing and uses a stand alone ecu that they can fully map allowing them map to a high compression and boost.

So what is the problem then with the current Z22SE SC conversions and knock/ignition control??
Are they not able to change the ignition timing for the problematic load cells individually?? (Only alter the ignition back and forth over the whole range for example??? notsure.gif '

winstar

exmantaa said:

So what is the problem then with the current Z22SE SC conversions and knock/ignition control??
Are they not able to change the ignition timing for the problematic load cells individually?? (Only alter the ignition back and forth over the whole range for example??? notsure.gif '

Yes they are able to change the ingnition timing which is what allowed them to change from using a decomp plate to keeping std CR, I may be wrong, but as they don't have an inlet temperature reading they will always have to map it safe to prevent knock if the inlet temps are high.

exmantaa

So... (bringing an old discussion to life here)
Why don't they put the T-sensor in the manifold then, like it should, and map accordingly?
(And that is also what must be done in the official GM 2,2 SC conversion kits..)

Or are they (still) not able to alter the T-sensor mappings? (I know the Dutch mapping guy has cracked this.)

alanoo

I think they are able to change the main ingnition map, but not the ignition vs air temperature correction

exmantaa

One reason more to pursue my LSJ ecu swap projekt... 😃

nickb777

One reason more to pursue my LSJ ecu swap projekt...

or the z20let ecu they are working on installing instead of the oem one

exmantaa

nickb777 said:

One reason more to pursue my LSJ ecu swap projekt...

or the z20let ecu they are working on installing instead of the oem one

Who is doing that? Courtenay??
Basically involves the same engine mods as the LSJ ecu; a 58-2 crank trigger + plus a cam sensor.

I know of one Vx220 who has finished a complete LSJ swap with the US P12 ecu and it's running fine with the VX E-pedal. He is now busy tuning things with the HP-Tuners program. cheers..

rik1083

took my saab cams out yesterday hoping it would fix my idle issues but didnt make any difference

alanoo

rik1083 said:
took my saab cams out yesterday hoping it would fix my idle issues but didnt make any difference

Are you running with the DTA ? So cable throttle, with or without an idle valve ?

rik1083

dta, no idle valve
even with the TB fully closed the engine idles at 1300 when warm! so an idle valve wouldnt help

going to pursue new intake gaskets (annoying have to order them from the us)
possible smaller tb (70mm seems a big big now)
then an idle valve

could also be map related.. the problem is when I try to lean it out to get to a 14.7 idle if I lean it any more than 14 then it start burbling and loses rpm.. under 14 it idle fine but high & rich but steady

alanoo

how much ignition advance at idle ?

Sounds strange it could rev to 1300rpm with the TB closed, where does it takes the air it needs ? notsure.gif

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