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Old 08-25-2010, 11:50 AM
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5.7 TBI performance upgrade questions

Hey guys, I just picked upa 350 4BLT main that im gonna build into a vortec motor, I have a 305 vortec in my truck now but I want to give it balls! not a airraid intake and exhaust right off the but those can come later, I need to know how radical I can go and still keep the throttle body injection system, cam? how bad should I build the heads, comp ratio, that type of stuff, so if you have some ideas to help a man out then holler. Thanks!

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Old 08-25-2010, 01:11 PM
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Quote:
Originally Posted by cproc501
Hey guys, I just picked upa 350 4BLT main that im gonna build into a vortec motor, I have a 305 vortec in my truck now but I want to give it balls! not a airraid intake and exhaust right off the but those can come later, I need to know how radical I can go and still keep the throttle body injection system, cam? how bad should I build the heads, comp ratio, that type of stuff, so if you have some ideas to help a man out then holler. Thanks!
The TBI needs a computer, a lot of wire harnesses and sensors to operate, do you have that stuff and if so is it for TBI or something else? What runs a Vortec system (1996 and up) isn't compatible with the earlier TBI set up.

TBI is very manifold vacuum sensitive, cam timing about 200 to 215 degrees measured from .050 inch lift is about it. Even this may need a new chip, certainly beyond this will, but you can't go much beyond this. You can build a 330 -350 horse engine with TBI and L31 Vortec heads.

Bogie
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Old 08-25-2010, 03:36 PM
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I apologize, It is a Vortec 5.0 in it now, runs fine, I am building a short block out of a 350 4blt main, I was just wondering how radical I could get and still use the vortec fuel system, I am ready to replace the computer or chip if neccessary, but I was wanting to avoid switching t a carb set up if I could, but I may not be able to get the sound I want or power from the vortec setup, might be easier and cheaper to go with a victor jr and a holley, I have heads to go either way. Thanks for the reply
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Old 08-25-2010, 03:43 PM
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Where to start What year is the truck? Also you may want to go Here! www.fullsizechevy.com tunning chips upgrades its on there!

Craig
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Old 08-25-2010, 04:09 PM
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It is a 1997 Silverado, L460E trans, I got a spacer under the throttle hookup and a cold air intake, thats about it. Currentaly a 5.0 but aspiritions of 5.7.
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Old 08-25-2010, 09:20 PM
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The 1987-1995 injection was TBI and used 2 injector that sprayed into the wet intake manifold.
The 1996-1999(trucks,1996-2002 vans)Vortec 305/350 is called CSFI(central sequential fuel injection) it run a 2 piece plastic upper plenum and an aluminum lower intake manifold.

TBI305 170hp/260 lb/ft torque
TBI 350 200hp 300 lb/ft torque
L30 Vortec 305 230 hp@4600rpm 285 lb/ft torque@2800rpm.
L31 Vortec 350 255 hp@4600rpm 330 lb/ft torque@2800rpm

So far as a stock L31 in place of an L31 its a drop in affair. The same T-body, injectors,e xhaust manifolds, air intake, MAF, even the PCM is the same, just flashed with a different calibration.

The highest dyno I have seen of a stock Vortec intake manifold and fuel injection is 330rwhp and 381 rwtq (almost 400hp 460 lb/ft torque)with the GM LT4 Hotcam 218/228║ 0.525"/.525" 112║LSA, home ported L31 Vortec 350 heads, 383 shortblock, stock intake and poppets, Ed Wright FAstchip PCM tune, Hooker Competition Series longtubes 2462 1hkr LT headers 1 5/8" primaries and 2 1/2" collectors
The same setup on a Vortec 350 shortblock made 305 rwhp. This is in a 1997 extended cab 2wd truck and ran 13.6 at 100mph with a 3000rpm stall Vigilante TC.

the stock intake manifold has all teh fuel poppets, FPR and fuel feed to teh poppets actually inside of the intake plenum thus obstructing airflow. teh poppet injector canot be upgraded to higher flowing units. To get around that I installed the GM/Mercruiser marine intake manifold. I am now running 24 lb injectors that flow 28/3lb/hr at 58psi(4BAR) of fuel pressure.

If you are planning of forced induction, the max poer will be much less due to the fact that forced induction takes much more fuel to make teh same amount of power when compared to a naturally aspirated setup.

Here is the link to the PAcific Performance Engineering truck site. There are lots of smart guys wityh huge Vortec engine experience and are a great group of guys. It is where the 411 PCM swap and the marine intake retrofit was invented and posted for all to enjoy.

PPE site
http://www.pacificp.com/forum/index....e805d5d626670f
Marine intake
http://www.pacificp.com/forum/viewtopic.php?t=317
411 PCM swap(this thread has a twin tuirbo install on a stock Vortec 305 engine along with an intake manifold from a crate RAmjet 350 engine.
http://www.pacificp.com/forum/viewtopic.php?t=3240

You can use stock L31 Vortec 350 heads
or
GM Perfromance PArts 1800 cc Bowtie Vortec iron heads
or
GM Performance parts 217 cc intake port Bowtie Vortec iron heads
or GM Performance PArts 210 cc intake port Fastburn aluminum heads(these heads are used on the 425hp ZZ383 crate and the limited edition 430hp Fastburn 350 crate engine of which GM only made 430 of these engines total
or
Edelbrock ETEC170cc intake port aluminum heads
or
Edelbrock ETEC 200 cc intake port aluminum heads
or
RHS iron Vortec heads, they flow a bit better on the intake than the stock GM Vortec heads
There are a few other aftermarket heads as well. If you are running the Vortec injection, just be sure to get real Vortec heads as they use a raised runner design and even if other non-Vortec heads are drilled for the Vortec pattern, teh port mismatch will be large thuis being a restriction.

All of the above heads will work with the Vortec 305/350 intake manifold and injection.

EFILive and HPTuners do not support the 1996-97 Vortec trucks, Tunercats OBD2, Westers Garage GMT and JET DST are all tuning systems that allow for full self tuning. EFILive and HPTuners support teh 1998+ 4.3, 305,350,454. If yous wap to teh 411 PCM and use a calibration from a 2001-2002 Vortec 350 CHev express van. The 01-02 vans were the only SBC's that are controlled with teh modern dual 80 pin 411 connector PCM AND a diistributer. Most engines that used the 411 PCM are CNP or coil near plug ignition.

You ca install a 24x crank reluctor from a 1998+ Vortec 454 RPO L21 that is modified to fit on the stock Vortec 305/350 crank under the front timing cover and by using a 98-2002 Camaro/Firebird calibration if you wish to retain teh cable throttle, or use a Corvette calibration in the 411 PCM if you desire to go with the ETC or electronic throttle control. Using the Vortec distributer WITHOUT the rotor and distributer cap, the now naked distributer is used for its 1x camshaft position sensor pulse alone. Now you can run the CNP 8 coil ignition.
The L21 Vortec 454 was used in the 1998 P30 van, and the medium duty Kodiacs. Its isopretty much a L29 Vortec 454/7.4 but uses a 24x crank reluctor, specifric L21 crank position sensor, capless distributer, 8 coils, and an electronic throttle. Its pretty much thinks its an LS1 Vette with more displacement. This was a rare engine and is suspected to have forged guts as it is considereably more costly than a normal lighttruck Vortec 454.

Swapping to teh 411 PCM in a Vortce 305/350/454 truck allows any tuner who tunes with EFILive or HPTuners to be able to tune a 1996-97 GMT400 Vortec 4.3/305/350/454 truck.

The Ramjet 502(502hp), Ramjet ZL1 all aluminum (493hp@6100rpm) crate engines specifically for the Vortec 350 fuel pump. I have seen a Ramjet 502 Tahoe with a 200 hp wet nirous oxide shot running the stock Vortec 350 pump. This means the stock Vortec pump will be fine for any smallblock combo.

I know of a coupel guys who have a GM LT4 Hotcam in their L31 350's and want to step up to a larger cam.
I am running a stock Vortec 4.3 L35 V6 torque converter behind my stock longblock Vortec 350 and with the throttle wide open with the rear tires locked, I get 2800rpm on the tach. Before I got 1600rpm of stall. With this TC tehre is muych less rpm drop during WOT upshifts.
I used to shifty at 5500rpms and the tach woudl drop down to 3400rpm for 2100rpm rpm drop during WOT upshifts. Now the same 5500rpm shift nets 3800rpm for 1700rpm during WOT upshifts. No longer is there any bog in acceleration like with the stock Vortec 350 TC, it just keeps pulling through the WOT upshifts.


So long as you have enough fuel supply, and cam, heads etc., the PCM can be tuned for it. It becomes a problem when the stock Vortec 305/350 intake manifold/poppets are pushed to hard, inconsistent fueling rears its ugly head, esp/ in forced injection applications that use rising rate fuel pressure regulators.

I would stay fuel injection, but thats just me. The response/torque and driveability is hard to beat with a carb. If forecd induction is planned, I would 100% stay with injection.
Any intake that has injector bungs and that fits the Vortec intake bolt patter. can be controlled by the 4 connector blackbox Vortec or 411 silver dual 80 pin connectored PCM. Hook up all teh sensors, snip off the stock injector wites (16 wires) then wire up the injectors. The 411 and blackbox PCM both control any high impedance injector. i wired up my marine injectors myself and I am not electronics guy AT ALL.

Any questions post back,



peace
Hog
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