I was formerly running a 350 w/ a 218/228 GM Hot cam and had it running pretty good and decent mileage(was driving 300+ miles a week). It was kind of annoying, especially when I got stuck in traffic and really hot out lol.

Anyhow, that motor has met its demise and I have a 383 installed and still playing around with everything and havent gotten it up and running yet.

Doing the math the 383 is roughly 9-10% bigger than the 350 it is replacing. Using the same logic on the factory camshaft puts it roughly at the 220ish intake and 224ish on the exhaust w/ the lift in the .470 area roughly.

I am using a Crane Cam w/ 1.6 rr's in my 383 it specs out about 217ish intake and 221ish exhaust w/ lift in the .500 area.

Has anyone here gone to a 383 tpi setup like this, where the numbers worked out, or at the least were very close like mine? I realize it wont be a perfect match for the stock tune, especially since I wont be running egr either(vortec heads). Planning on trying all this on a stock aujp w/ adjusting the Inj. Constant and the cylinder displacement and the obligatory 2-3 timing pulled across the board for new stuff.

I know the torque curve(VE tables) and the timing curve will need work to get them back to their optimums. I'm also sure I will prolly have some AE issues w/ the larger displacement most likely as well.

Never tuned something that was as close to stock mathematically like this given the increase in displacement.

And yes, I do know to try it and see what happens, but I want some popular opinions in the meantime. I still have a few days before it will be fired.

later
Jeremy

 

Jeremy-

I ran a 383 with Vortec heads, large runners and a cam that had around 480 lift. Don't try to make correlations like that. the engine package still has a personality all it's own that you will need to tune for. Mine ran MAF, but even after adjusting the injector constant for the bigger injectors I ran, I still had to redo the maf tables, AE, timing, WOT, and other items...just like any other tuning project.

Enjoy

 

lol Wasn't assuming anything :-) It is a SD 91 Formie

Just for once hoping that maybe it would be driveable/liveable as I have a chance to work on the tune. I'm still thinking I'm going to have to play with it whatever I do, but it will be a lot easier to manage than the hotcam in a 350.

It will never have a "perfect" tune either. Still play with my GTA when i ge tthe time and its almost stock. The old 350 in the Formula was pushing the dipstick out of the tube and i was still goofing around with things tunewsise at the track lol (couldnt hurt it anymore)

What were/are your cam specs in your vortec headed 383 and how did she do?

later
Jeremy

 

Had 264/274 advertised duration.

I think you might be able to drive your car, but I would not expect anything more than marginal performance until you tune it.

 

Big cams mean less and less as the CID increases. A bigger motor will consum more air everywhere, and the max torque, and HP levels move around.

When I was playing with my big motor, I just played with the inj constant to get the engine to start and run, then went just figured the difference in using the wrong inj constant, and applied that to the VE table, and reset the inj const to what was actually correct. Then it was just a matter of figuring out where max Torque was, and using the WB.

 

Thats a good one there Bruce lol

Never thought of giving it a shot that way.. Something I'll prolly try and use and give the VE a good roughing in when I get it fired up...

Havent had alot of experience on pushing the cubes past the point they left the factory. I just know that the more of them I have the faster I will go if I get it all dialed in.

Guess my worst case is getting it running well enough to break in safely(that should be easy part). After that I can just use the Romulator and go for a few global changes using the IC and figure out the main changes to the VE.

I'm smelling sacrificial wideband sensor for my Innovate :-( Guess I wont worry about the wideband right away unless I run into some strange issues

later
Jeremy

 

Everything being equal increasing the cubes of a motor will shift your VE down and maybe even increase it depending on the bore and stroke changes.
With larger cubes the engine will want more air on each revolution making the heads that were "big" on a 305, small on a 350, hence the shifting of the VE table.