420 SBC project..was Re: selection of TBI components for 383 Chevy

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Curtis L. Martin wrote:
> 
> > Curt, I'm interested in your 420 project and in particular what you
> > plan for the fuel injection system (and the engine internals).
> > Please email me directly if your comments are not related to
> > this forum. I am still seeking this groups input to help me select
> > appropriate TBI components for a high torque 383 truck engine.
> > Thanks for your input.  Steve
> 
> Sure,
> 
> The block is a 2-bolt 400 ('78 Blazer) bored 0.030" over and fitted with
> Mildon splayed 4-bolt caps on the center three webs.
> 
> The rotating assembly was purchased as a kit from Larry's Performance Shop,
> in California.  It consists of a 3.875" stroke, forged crankshaft, 327 5.7"
> connecting rods, and custom JE reverse dome forged pistons.  It took a
> while for the kit to get here, but so far it looks like it was worth the
> wait.
> 
> Camshaft is a Crane 113801 camshaft (flat tapped hydraulic, 222 in 234 ex
> @0.050 lift, 114 lobe separation, .467 in lift, .494 ex lift)
> 
> Cylinder heads are GM 10088113 Aluminum Center-bolts and are more or less
> stock (valve diameters)  I just added Crane valvesprings, studs, and
> guideplates.
> 
> I'm shooting for a finished CR in the 9.8 range.  The block is being honed
> (in fact it should be done by now) so I'm waiting to see what the final
> deck height is and compute the actual CR.  If it's over 10:1, then I'll
> have to re-think a bit, take material out of the head chambers and use
> thicker head gaskets to lower the CR.
> 
> Rocker arms are also Crane 1.6 roller. (These are left-over, narrow body,
> non-self aligning rockers from my previous 2.8L, hence the guide plates.
> It was cheaper to buy 4 more rockers and add the guideplates, vs. a new set
> of 16 self-aligning rockers.)
> 
> Timing chain is a toss up.  I have this Erson Gear Drive, but I'm debating
> installing it.. might just go with a good old Cloyes double-roller chain.
> The good point about the Erson is that the cam cover is removable..
> allowing a cam swap without disturbing the bottom of the motor.  I think I
> will install it and at least try it out.. but at the first sign of trouble,
> it'll get chucked in favor of a more traditional chain drive.
> 
> Induction is still an open issue...  The plenum/runner config I would like
> is the TPIS Mini-ram.  The motor should have excellent low rpm torque
> without relying on a long runner intake to enhance it.  I would rather use
> the LT1 style short runner manifold and try to increase the top end of the
> power band.
> 
> At one point I considered using a Holley 900 CFM Projection 4di on top of a
> Weiand 142cid supercharger.  Holley's tech support killed that idea in that
> they will not support or recommend blower apps for the 4di.  They would not
> elaborate as to the reason why.  Based on displacement and a rpm limit of
> 5500 (self imposed..I'm not going to spin this motor to 7000rpm), 900 CFM
> should be just about right. (or just 700cfm without the blower)
> 
> ECM is also a toss up.  There is a GP in process on the 3rd Gen F-Body list
> for Haltech E6GM.  The other option is stock GM map ECM with a custom
> calibration ala AS&M's CARprom.  At this point I'm considering doing both..
> initially running the Haltech to gather data and define the basic fuel and
> timing maps, then revert back to the GM module (using the information
> learned in phase one as the starting point)  That will free up the Haltech
> for the next project.  I get an un-easy feeling relying on an aftermarket
> ECM for long term use.  My luck it will crap out at the most in-opportune
> moment, leaving me stranded and unable to repair it.  At least with a GM
> ECM, I can always scrounge one up in an emergency from a dealer, auto-parts
> store, or junk yard.
> 
> Transmission will be a 700R4 with 2200 rpm stall converter.  Final gear
> ratio is 3.42 with Auburn LSD in a 10-bolt axle.  The car is a 3400lb '87
> Camaro.  The large amounts of aluminum going into this motor should lighten
> the car down another 100 lbs, but I'm planning on adding a roll cage to it,
> so the weight should remain about the same.
> 
> The car is currently MAF equipped, so that's going bye-bye, along with the
> cold-start injector hardware, regardless of manifold choice.
> (That reminds me.. I've got to go scrounging for a intake duct to replace
> the MAF sensor... details, details, details..;-)
> 
> I have no idea right now on the selection of a knock sensor.  I guess all I
> can do is use the GM 350 ESK module and hope for the best. (Suggestions
> welcomed)
> 
> Ignition with be stock HEI.  I also plan to leave most of the emissions
> gear that I have installed and functional.. which means having the
> tube-steel headers equipped with a EGR flange, since the heads do not have
> provisions for internal EGR.  I'm not looking forward to this.. probably
> scrounge the basic plumbing off of a V6 Fiero or similar platform with tube
> steel manifolds and external EGR.  (Fiero owners forgive me :)  Then have
> the flange welded to the #8 cylinder exhaust header tube... similar to the
> Corvette arrangement.
> 
> The car is also fitted with a CompuCar nitrous-oxide (wet manifold) system.
> 
> That's about the long and short of it.
> 
> Curt Martin (cmartin at america.com)
> Ormond Beach, FL
> http://www.america.com/~cmartin

Curt, There is much to discuss here. We are for the most part building
the same engine. The one point I will comment on for now
is the ECU selection. (more later)
I agree with you strongly on the use of the GM ECU for reasons of
reliability, availability and cost. I took apart a dead Holley
Projection ECU in 1993 and was amazed to see the types of components
used for an automotive-temperature-range device. No wonder it was
dead. I'll stick to a GM ECU.
Steve