1994 k1500 383 tbi

[PlayingWithTBI]

Best I can tell on the injectors

Yep, 61 #/Hr @ 13 PSI ones for 5.7L

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[Taz069]

Yeah, I was thinking about a pusher fan and keeping the 11 blade, severe duty clutch for my main cooling here in the desert. It does need help at idle.


Look at that again,,, 295 lift intake and 500 exhaust??? Shouldn't that be 495? My 383 has the XR282HR cam with .510/.520 and 230/236 @ .050 for 436HP - dyno proven, just saying...

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@PlayingWithTBI doesn't a crank of 3.750 toss and a rod of 5.7 give you a different cubic inch ratio? Well depends on compression? Not actually utalising the true stroke. Block cleanances have to be machined for the 6.0 rods where 5.7 doesn't? So which is a true 383? Short stroke a 4.030 block with a 5.7 rod and raise the compression? Or use the 6.0 rod for actual total long stroke of a 383? I am thankful for all input. I learning also

 

[PlayingWithTBI]

So which is a true 383? Short stroke a 4.030 block with a 5.7 rod and raise the compression? Or use the 6.0 rod for actual total long stroke of a 383? I am thankful for all input. I learning also

a 3.75" stroke by 4.030" bore gives you 383 (mine is actually 377 - 4.00X3.75), a 4.00" bore with 3.80 stroke gives you 383 too. A 6" rod gives you different angles when stroking but, doesn't effect Cu In.

 

[Road Trip]

Best I can tell on the injectors

The last 3 numerals are '206', which match the stock 5.7L
#55 lb/hr injectors listed on the chart I posted in reply #11.

If you were putting together a stone stock 5.7 Vortec, then what
you have + stock fuel pressure & you would be good to go.

But @Tim W shared the following:

For what it's worth I was going for the same build (ish). I was told all kinds of things (I needed this, I needed that ect).

I contacted Brian Harris at TBI chips and after sending him my engine build sheet, which had cam specs, he told me that it would be difficult to "burn" a chip that wouldn't be too lean even with the right fuel pump and Regulator.

I ended up going with a Holley sniper bc it has an internal Regulator. Just a thought

I wasn't part of that conversation, but I'm assuming that Brian at TBI chips was
concerned about the engine breathing more air than the 55lb/hr injectors could
keep up with. (ie: keeping WOT A/F ratios at ~12.5-13:1 at peak torque > peak HP.)

Notice that the 5.7 "cop cars" got upgraded to 65 lb/hr injectors. Since I don't
know how your deeper breathing 383 compares to the factory police cars, I
have no idea if this would keep up/give you an adequate safety margin.

So that leaves us with the 2" bore big block TBI setup with larger flow injectors.
(I've attached a partial screen snap of an ebay auction to give you an idea --
but NOT a recommendation to purchase.)

Instead of paying that kind of premium, you should go out to your local pick-n-pull and
locate one of these. (YOU pull it off of the big block, so you *know* it's the right one.)

For what it's worth I just pulled the latest price sheet from a nearby pick-n-pull, and
they want ~$32 for a 'carb or throttle body'.

****

Now, fast forward a little. You lucked into a complete big block TBI assy for the right
price, paid someone to clean/test/verify that they are working today the same way
they did when originally manufactured. Good. Of course, if your stock intake is
set up for the 1 11/16" bore of the original TBI, you should first have the intake
manifold bored out to the same 2" diameter to match your new big block throttle body.

NOW you have maximized the airflow for your TBI setup, and you have injectors
sized to support the kind of power that you are making. The next step to
do is you are going to start out slowly with tuning your setup, NO full throttle
right off the bat. (I would go so far as to set up a temporary part-throttle stop
to make sure I didn't overdo it in the beginning. (!)

Instead you are going to get the idle & part-throttle tune sorted out. And once
that is done, you are going to up the throttle angle in steps, making sure that
the system continues to keep the power A/F ratios safe. (ie: you don't run into
an engine-damaging too-lean fuel delivery bottleneck.) After maybe 3-4 incremental
steps, you will finally end up with a safe full-throttle A/F ratio for *your* engine.

Why? Baby steps are way better than burned/holed pistons from going lean during
full throttle. And when it comes to tuning that TBI, whatever @PlayingWithTBI says,
that is exactly what you should do. In 2023 there very very few people with successful
'hands-on' real-world experience still tinkering with the TBI setups. And elsewhere
in this forum he has detailed the specifics of what he's done -- has the ring of truth,
especially since he's driving what he's talking about! :0)

And if you take the time to learn the details behind all this, it will serve you well in the future.

 

[Supercharged111]

a 3.75" stroke by 4.030" bore gives you 383 (mine is actually 377 - 4.00X3.75), a 4.00" bore with 3.80 stroke gives you 383 too. A 6" rod gives you different angles when stroking but, doesn't effect Cu In.

Doesn't it give the piston more dwell time at TDC? That, the operating angles throughout the stroke, and it buries the wrist pin up higher into the ring lands which was already mentioned.

 

[Road Trip]

@PlayingWithTBI doesn't a crank of 3.750 toss and a rod of 5.7 give you a different cubic inch ratio? Well depends on compression? Not actually utalising the true stroke. Block cleanances have to be machined for the 6.0 rods where 5.7 doesn't? So which is a true 383? Short stroke a 4.030 block with a 5.7 rod and raise the compression? Or use the 6.0 rod for actual total long stroke of a 383? I am thankful for all input. I learning also

Taz069,

Good question! We're going to define some short block terminology using SBC
examples, and this along with the 5 photos below should make all this snap into
sharp focus.

Deck Height: (Simplification) The total distance that we have to work with
between where the crankshaft is bolted in versus the surface that the cylinder
head is bolted to. The SBC deck height is just over 9". (Actually 9.025")

We simply have to fit 1/2 of the stroke that the crankshaft gives us + the effective
length of the connecting rod + the distance between the centerline of the wrist pin
to the top of the piston.

That's it - we're only juggling a total of three variables. If we get it right, it all just fits.
Get it wrong, and either the piston is pushed out of the top of the block at TDC (Top Dead Center)
or the bottom of the piston scrapes against the crankshaft counterweights at BDC.
(Bottom Dead Center)

Compression Height: That's the official name for the distance between the
centerline of the wrist pin and the top surface of the piston.

Now, let's look at the 3 photos I've attached.

Photo #1: Pistons for a 302ci SBC. (aka: DZ302 Trans Am engine) This is a piston
for a 3" stroke & 5.7" long connecting rod. Check out all the distance between the
wrist pin and the top of the piston. (And the oil ring land too!)

Photo #2: Piston for a 350ci SBC. This piston is for a 3.48" stroke and a 5.7"
long connecting rod. If you look carefully you can see that the wrist pin is just
this side of encroaching on the oil ring land.

Photo #3. Piston for a 383ci SBC. These pistons are set up for a 3.75" stroke
and a 6" connecting rod. Your pistons should look similar to these. Note that
in order to make room for the longer stroke + the longer than stock connecting
rod, the piston's compression height is quite a bit less than the other 2 examples.
(And be sure to check out where the wrist pin ends up vis-a-vis the oil ring land!)

****

Set up properly, a modern long-rod 383 SBC is the engine that Chevy should have
built back in the day -- it's an overachiever.

With the above, you can now add Deck Height & piston Compression Height to your
motorhead lexicon. And the ladies will swoon when you share this with them.

All we're trying to do is add more and more cubic inches of displacement into
a finite space...

Hope this explanation helps!

 

[langkg]

tbi no more 383 need to go with a holley or something like it if you have a automatic if it is a manual you can go carb dont waste you time on the tbi you payed good money for a 383 than dont hold it back with bad fueling

I agree with J1985. You'll be time and money ahead by using a Holley Sniper with that much engine. Yes, you'll have to pull the bed or drop the tank and change your fuel pump for more pressure and do a little wiring but well worth it. The Sniper 2 is out now and you will eventually be able to control auto trans with the module to be released.

I am running a Smeding 383 on a Sniper first gen. Engine makes 425hp / 475 lb-ft. which is similar to what you are trying to do with your build. You will also need to bump up your stall if you're running an auto trans.

I would spend your money on the above mods rather than electric fans. I'm running the stock mechanical fan and radiator and have no problems what soever even on a hot summer day with the AC cranked. If I needed additional cooling, I'd swap in the larger radiator from a big block and still run the mechanical fan. All you need to do that is shrouds and the radiator and probably new hoses. There is space in the core support. This was my original plan but found the stock cooling arrangement to be just fine.

 

[Taz069]

Taz069,

Good question! We're going to define some small block Chevy terminology,
and this along with the 3 photos below should make all this snap into sharp focus.

Deck Height: (Simplification) The total distance that we have to work with
between where the crankshaft is bolted in versus the surface that the cylinder
head is bolted to. The SBC is real close to 9". (Actually 9.025")

We simply have to fit 1/2 of the stroke that the crankshaft gives us + the length
of the connecting rod + the distance between the centerline of the wrist pin to the
top of the piston.

That's it - we're only juggling a total of three variables. If we get it right, it all just fits.
Get it wrong, and either the piston is pushed out of the top of the block at TDC (Top Dead Center)
or the bottom of the piston scrapes against the crankshaft counterweights at BDC.
(Bottom Dead Center)

Compression Height: That's the official name for the distance between the
centerline of the wrist pin and the top surface of the piston.

Now, let's look at the 3 photos I've attached.

Photo #1: Pistons for a 302ci SBC. (aka: DZ302 Trans Am engine) This is a piston
for a 3" stroke & 5.7" long connecting rod. Check out all the distance between the
wrist pin and the top of the piston. (And the oil ring land too!)

Photo #2: Piston for a 350ci SBC. This piston is for a 3.48" stroke and a 5.7"
long connecting rod. If you look carefully you can see that the wrist pin is just
this side of encroaching on the oil ring land.

Photo #3. Piston for a 383ci SBC. These pistons are set up for a 3.75" stroke
and a 6" connecting rod. Your pistons should look similar to these. Note that
in order to make room for the longer stroke + the longer than stock connecting
rod, the piston's compression height is quite a bit less than the other 2 examples.
(And be sure to check out where the wrist pin ends up vis-a-vis the oil ring land!)

****

Set up properly, a modern long-rod 383 SBC is the engine that Chevy should have
built back in the day -- it's an overachiever.

With the above, you can now add Deck Height & piston Compression Height to your
motorhead lexicon. And the ladies will swoon when you share this with them.

All we're trying to do is add more and more cubic inches of displacement into
a finite space...

Hope this explanation helps!

 

[Taz069]

These are what's being used

 

[PlayingWithTBI]

Doesn't it give the piston more dwell time at TDC? That, the operating angles throughout the stroke, and it buries the wrist pin up higher into the ring lands which was already mentioned.

This is what confuses me;
1. It's still 3.75" stroke so, no more Cubes Added at same RPM (Stroke X Bore X # Cyls)
2. With .300" more rod, (or whatever), same Deck Height, there's less angle at TDC/BDC - S/B less dwell angle, not more dwell time IMO. It may slow down faster but will spend the same amount of time at 0 Dwell.

Every time I think about it, I just get a headache AFAIAC - either way isn't too big of a deal when we're talking SBC in a truck!

Time for some more stimulation!!!