OK since i didnt have time to explain in more detail when i posted these....

well it looks like it will be easier to modify the SII cam (redneck wise) and get it to work than just changing 4 lobes on the SI cam (cast iron-4 lobes are out of phase)
the SII billet steel would be easily (fairly) made to work by welding alongside the lobes that need to be "Moved" over to line up with the SI block lifter bore spacing pattern, and then using a simple follower jig with a belt sander/grinder grind the extension to the same pattern as the original next to it, polish it and grind away the old (original) portion of the lobe to maintain lobe to adjacent lifter clearance....
and this cam can easily be made into an aftermarket billet steel camshaft with any custom lobe profile you desire...we may eventually get one but fer now...it's Lowbuck


annnnd.... the lifters are identical in every way...and look very similar to the sbc/ or 3x00 seried hydraulic roller cam engines (will hopefully confirm... and there may be a factory lifter out there with a larger roller that can handle a faster opening lobe ramp)

I may have to use the SI timing shain but that isnt an issue at this point (i believe that the cam/crank centerline measurments are identical (well i could have been .010 off)
i could use either...but i wil be deleting the balance shaft in the lifter valley (block oil holes) and will be cutting down the balance shaft gear to just a spacer...if you notice there are thickness differences in the SI vs SII timing compnents...they are different but stacking the parts together SI and SII components are the same thickness....as a unit...the SII chain and gears have a smaller tooth pitch pattern but share a nearly identical Tchain tensioner...

the cam retainer plates are the same thickness and opening diameter, just different bolt pattern...no problem there



and here is the SII crank gear (didnt have the SI on me) besides the smaller tooth pitch it is identical to the SI unit...however the SII drives the oil pump by 6 splines as opposed the the SI's two flats design...this is irelevant as the pump assemblys and Timing chain covers are nearly identical...just swap the pumps from the SII cover to the SI T chain cover....

Things seem to be looking up with this! Looks like the major obsticle is the cam?

yes the cam is the fun part soo far, but i think i have figured the easiest way to accomplish what i need to get the SII cam to work in the SI block...easier to change a billet steel cam than a cast iron though the cast iron cam only needs 4 lobes changed by swapping the lobe phasing...but they would have to be custom ground to match the other lobe profiles...but for less investment ($ wise...time is nothing...i have no life lol) the SII cam is getting chosen...plus after all of this i can check it for straightness with two Vblocks straighten it and then turn down the cam bearing journals...maintaining what should be perfect concentricity

i know not many of ya are riveted by this...but i'm enjoying it....you should see how greasy the notebook is....lol

James

So let me make sure I have got this. You are using a SI bottom end with a SII top end on it? The advantages, aside from being just plain cool, are that the better bore/stroke ration of the SI with the better top end of the SII, and the availibility of good aftermarket parts, make the ultimate 3800? Good idea with the cam btw, but I have one question. Are the firing orders the same? If not, how can you correct it so that the SII cam isnt opening the intake valve (or a similar enevt happening) when it plug fires? I am intrigued, and am looking forward to the next installment of "redneck engine-u-ity"!

Andrew

Hi andrewk, all,


Make that rod/stroke ratio. The SII heads are capable of making much more power than the SIs and probably account for all the power difference between the two engines. As I said before, 250 aspirated HP would be a piece of cake if the heads were done properly.

How much the better rod/stroke ratio helps, or if it does at all, is always open to speculation, but it gives him some extra options. If he stays under 6000 and lets the blowers do the work, the longer rods won't help a lot.


Not that much of a consideration.

What would be cool, would be kicking some supercharged 3800 SII a$$ with an aspirated SI.


Yes. The difference is: the mfr swapped the intake and exhaust valves, and the cam lobes #3 and #4 in the SII. SI lobes are out of place, and the properly phased SII cam is not a direct fit to the SI block.


He either needs to make the SI cam fit the SII layout, or make the SII cam fit the SI block.

Looks like the SII cam will go in the block.

Regards, Norm

the firing order is the same for the 93 SI and the 98 SII block...my guess is all of them have the same firing order but i am not 100% sure

165432 with the wasted spark ignition system coil pack pairing is: 63 25 41

gotta start welding that cam soon....

Hi Turbocharged400sbc, all,


165432 was used on all GM gas V6s. It should include SIII, but that's a guess.

Regards, Norm

OK fer an update....

i was talking to my buddy down under, (Locksmiff on Streetcommodores.com,) who started a seperate invite only tech site for holden commodores...(weee i'm one of 120 select few who know their sh!7! lol...naw he started it to keep the flammers out from the other holden boards and concentrate on going fast/tech articles...i wish i could let you see some of the stuff there...but i wont...i will copy and past fer you guys when i find something relevant to Brando and ya'll)

but too the case at hand...

I have some pics of the SII stuff mocked up on his Holden SI (same as ours but has different intakes and exhaust (they got RWD but not quite the same stuff as the F body 3800 stuff...)

here are the SII heads on the SI block...

The cover over the balance shaft kinda hides the lifter bores but here is a valley view (btw i have never seen that blance shaft cover on an american engine...we think this is because of the high temps of the Au market...keep oil from coking on the underside of the intake)

And the money shot...here is the SII Holden intake bolted to the head...you can see the 1 inch gap that would have to be filled with spacers...or the SII intake widened...

and here are a couple of shots of the holden SII upper and lower intake manifold...similar to the F body setup but not quite...



now if you look at the lower holden intake it might be easy to cut it in half down the middle and widen it (cut zigzag between the runners and straight down the middle on the bottom) and then weld in filler for the coolant "T" and just fabricate a sheetmetal common plenum for the top...
alteernatly we have been talking about just making a custom (sheet aluminum) lower intake as a tunnel ram...which would be great for a NA engine but on our turbocharged setup ahort runners would work just as well...

well i hope that gives ya'll some more stuff to chew on....

I hope to get my own SII heads here soon so that i can start mocking up pushrod angles etc...but the heads bolt on nooo problem

James

Hi Turbocharged400sbc, all,


Fabricated manifold is not hard to do, just time consuming. Also gives you complete control of it's design. Doesn't necessarily need to be a "tunnel" design.

Regards, Norm

well from what i have looked at a runner length of ~5-6 inches would maximize lowend/midrange power...so if we went the custom route...thats about what i would put them at...at the min no less than 4 inches runner lengthas it would raise the power curve to high for us to use effectively as we dont want to rev over 5600 rpm...and to keep from buying lightweight valvetrain components to prevent float...

Lowbuck all the way...

Hi Turbocharged400sbc, all,


Forgot, you're using blowers. My experience with them was long ago, but here goes.

Runner length (ram tuning) can be a big help in aspirated engines, while in your application length is not a factor. In either case, they need to be as straight as possible. Top priority is keeping turbulence at a minimum.

Regards, Norm

runner length is always a tunable component in any engine...from NA (14.7 psi) or any "boost" over that...compressed air has that much more weight/mass and still behaves as a fluid...so tuning the runner length (longer for better low rpm pulsing....and shorter for higher rpm air charge filling)....i am looking for great bottom end and midrange power so i would like to have a 5-6 inch runner length (with even crossectional area-to maintain port velocity) essentially this applies also to port crossection...smaller vs large area ports etc.

yes with any forced induction this becomes less of a major tuning factor but every little bit helps...and it may be less of a concern on a turbocharged engine as most (properly designed) systems have a certain amount of exhaust backpressure (before the turbine scroll)..which is why most Turbo cams have little overlap of the intake and exhaust lobe timing events...to help prevent reversion/intake charge contamination

i have been doing a bit of reasearch on the subject...
i just wish i had enough $ and could get THIS (believe it or not a buick V6 is shown near bottom)

ahhhh the miracles of modern CAD/CAM work on engine development/efficiency testing...gotta love it

Hi James, all,

Thanks, waiting for the next installment.

Regards, Norm

lol

waiting to buy this 125$ L67 engine (spun bearing) so i have a set of SII heads to play with....

I still need to get pics of the T chain covers (and their minor differences) as well as the chain tensioner and oil pump drive sprocket/scroll

i am still amazed at how truly similar these two engine's are....

well monday i am off and i will be getting more pics and measurments of the SI and SII engine's in Al's garage

specifically the timing covers, and the piston/rod assemblies...