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Old 12-28-2006, 06:54 PM
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LT1 Question

If I was going to install a LT1 in my project which one is best?? If i understand things correctly there are 2 types one uses a mass airflow sensor (just like on my 93 TA) and the other one that would be better uses a Manifold air pressure sensor. I'd like to use an LT1 engine out of a 4th gen F-body or Impalla SS. Is there something I should look for, Is one better than the other?? ANy advuse would be great. Right now I'm just throwing this idea around..

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Old 12-28-2006, 07:10 PM
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I personally prefer the MAF system because the computers that go with it are flash memory, not PROM chips. If you get a 94-95 with the MAF and computer, you can write your own programming with a laptop. The 96 and 97s are flash, too, but they're OBD2 and the software and hardware is BIG bucks to do that.

The MAFs on most F-bodies are bigger at 3.5" compared to the 3" on the B-body and Y-body, but it hasn't shown to make any difference in cars up to about 400 hp.

The earlier non-MAF engines are a little simpler, but really... four wires? The MAF systems also take to aftermarket changes nicely; forced induction, nitrous, cams, heads... they take it all in stride.

Here's an LT1 link that might help you some.

http://www.automotiverebuilder.com/ar/ar99928.htm
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Old 12-28-2006, 10:02 PM
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94-95 OBD1 easiest to alter program. F-body cars have aluminium heads vs Impala's iron heads. 20HP advantage with f-body. F-body LT1 is about the same as Corvette with exception of accessory mounting and exhaust. I had one in a Jaguar and it moved that heavy car with ease.
Bob
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Old 12-28-2006, 11:44 PM
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Quote:
Originally Posted by bnewsom
94-95 OBD1 easiest to alter program. F-body cars have aluminium heads vs Impala's iron heads. 20HP advantage with f-body. F-body LT1 is about the same as Corvette with exception of accessory mounting and exhaust. I had one in a Jaguar and it moved that heavy car with ease.
Bob
Agreed. My daily driver is a 95 Z28. The 95 is considered by some to be the most desirable year due to the vent opti spark combined with OBD I. Of course, I may be biased.

Bob, my old next door neighbor had an XJ6 with an LT1 and a Turbo 400. I have to agree with you, they do run well even though his had, I believe, a 2.87 rear gear.
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Old 12-28-2006, 11:48 PM
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hows this??

http://cgi.ebay.com/ebaymotors/ws/eB...4386128&rd=1,1
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Old 12-29-2006, 12:29 AM
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Quote:
Originally Posted by bnewsom
94-95 OBD1 easiest to alter program. F-body cars have aluminium heads vs Impala's iron heads. 20HP advantage with f-body. F-body LT1 is about the same as Corvette with exception of accessory mounting and exhaust. I had one in a Jaguar and it moved that heavy car with ease.
Bob
If you actually want to split hairs, the iron Impala heads flow better than the aluminums. The F body LT1s made more power with the cam, not the heads.

Its not a huge difference, but its something like 8 cfms better on the iron.

Edit: A quote from the link above tells me I'm wrong... its more than 8 cfm

Quote:
HEADS
There were two heads used on the 350, one aluminum and one cast iron, along with one cast iron head for the 265. GM claimed that the original LT1 aluminum head had a 15% increase in airflow as a result of revised port angles and higher port ceilings when compared to the 1991 L98 head. That was impressive in 1992, but the iron LT1 head that came out in 1994 was even better. It flowed 20% more on the intake side and made more horsepower on the dyno
I think he's saying 20% more than the L98
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Old 12-29-2006, 12:05 PM
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Oh, one more thing to add. Mechanical differences aside, they are all pretty interchangeable. Finding a 94-95 would have all the parts you need, but it would be very easy to find a 96-97 and then retrofit it with an OBD1 computer. It will run it the same with some minor exceptions.

Give Bryan Herter a call over at pcmforless.com. He sets us impala SS guys up with OBD1 "conversions" so we can tune them at home. He's also a great tuner of both OBD1 and 2 stuff.
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Old 12-29-2006, 01:21 PM
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The 92-96 Vette LT1 is rated at 300 sae net hp 92-93 used a Speed Density setup, while the 94+ uses the Mass Air Flow Sensor (MAFS).
The 93-95 F-body LT1 is rated at 275hp. 1996-97's were 285 hp or 305 hp with the WS6/SS induction and exhaust enhancements.
The 1996 LT4 Vette and 1997 F-body LT4's are rated at 330 sae net, but are actually dynoing at 300 rwhp which works out to ROUGHLY 360 crank hp. The LT4 has LS1 power inteh older GEN 2 setup.

the 94-96 LT1 B-body (impala) was rated at 260 sae net hp, and uses the same cam as the 1996-2002 Vortec 350.

As stated earlier by curtis73, the MAFS system is more forgiving to cam, headers, air intakes, cam changes.

I have a tuning system for the GM OBD2 vehicles called Tunercats OBD2. I bought it last year new for $340, it came with 1 definition file for the 96-97 Vortec trucks.

here is a list of available definition files. the 2006 trucks are also supported.
OBD2_07 1996 - 1997 Vortec Trucks (4.3L, 5.0L, 5.7L, 7.4L)
OBD2_06 1998 - 2000 Vortec Trucks (4.3L, 5.0L, 5.7L, 7.4L)
OBD2_02 1999 - 2000 LS1 Trucks (4.3L, 4.8L, 5.3L, 6.0L)
OBD2_03 2001 - 2002 LS1 Trucks (4.3L, 4.8L, 5.3L, 6.0L)
OBD2_04 2003 - 2005 LS1 Trucks (4.3L, 4.8L, 5.3L, 6.0L)
OBD2_08 1996 - 1997 Camaro/Firebird/Corvette/Impala LT1
OBD2_09 1997 - 1998 Camaro/Firebird/Corvette LS1
OBD2_01 1999 - 2001 Camaro/Firebird/Corvette LS1
OBD2_05 2002 - 2003 Camaro/Firebird/Corvette LS1
OBD2_10 2004 - Corvette
OBD2_12 2004 - GTO
OBD2_13 2004 - 2005 Cadillac CTS-V

This system came with all the cables to hook up to the vehicle and my PC/laptop. There are hundreds upon hundreds of tables that I can change. Additional definition files are$79 and I could tune 10,000 vehicles from that definition file if I wanted.

Unfortunatley JET industries has bought the rights to Tunercats OBD2, and is now selling it as teh Jet Dynamic Spectrum Tuner. Its almost $500US and you get 2 definition files and can only tune a max of 4 vehicles. You can buy extra licenses for each definition file.
Fortunatley Tunercat customers are still supported by Tunercat, you cannot use a tunercat2 file with a Jet file.
For an inexpensive OBD2 tuner, its best to try and find a used Tunercats2 since Jet bought the rights, Tunercats cannot sell anymore Tunercat2 systems.
The Jet DST andf the Tunercat OBD2 setups are the ONLY setups that support the 1996-2000 Vortec 454,350,305 and 4.3 trucks.
These are just flashing and tuning systems, it does no logging or scanning.
A product called MXScan ($69.00) can scan and log even the GM enhance PID's using a laptop.

Also the info about the Impala SS iron GEn 2 heads flowing more than their aluminum counterparts is absolutley correct. These iron heads were needed by GM in 1995 for the 1996 model year production run while the LT1 aluminum heads were needed in 1991 for the 1992 production run.
Production timing allowed the GM engineers to play with the iron GEn 2 heads more than they could with the aluminum castings.
In matter of fact, the ports from the iron LT1 heads were stolen and used in the 1996-02 L31 Vortec 350 heads.

We are currently experimenting with installing the newer silver 411 PCM's in the 1996-1999 Vortec 350 trucks, and using a 2001-2002 L31 Vortec 350 Express Van tune to run the engine.
One of us is even going to install the 411 PCM into an OBD2 F-body. He is going to drill the LT1 intake for the L31 distributer(to get rid of the optispark).

The advantage of the 411 PCM over the 96-99 trucks blackbox PCM is that there is no internal 5800 rpm rev limiter, the 411 has dual spark tables, and tuning suites like EFILive and HPTuners can be used for tuning.
The advantages of teh 411 PCm over the black PCm's originally found in the Fbody LT1's are the same as for teh truck, except the Lt1 PCM doesnt have the 5800 rpm ceiling. the LT1 PCM's seem to shut the injector pulsewidth down at around 7200-7300 rpm according to Ed Wright.
The stock Vortec 350 rev limiter is set to shut off fuel at 5600 rpm and return fuel at 5400 rpm. I set the rev limiter to 6200 rpm and the revs were still limited to 5800 rpm. In fact there are many of us who have tried every major tuner in North MAerica and even internationally and NO ONE has been able to get around this 5800 rpm ceiling.
Since we have installed Vortec MArine MPFI and Ramjet MPFI intake manifolds on out trucks(to get rid of the restrictive intakes and small 19pph injectors), some of us have instaled cams, heads and valvetrains that can utilize 6000+ rpms.
Here is some links to the PPE forum(Pacific Performance Engineering).

411 PCM conversion
http://www.pacificp.com/forum/viewtopic.php?t=3240
http://www.pacificp.com/forum/viewtopic.php?t=3666


Marine Intake conversion
http://www.pacificp.com/forum/viewtopic.php?t=317

Picture of the GM/Mercruiser Marine intake manifold, before Merc sprays them with red paint.
http://www.sfatek.com/images/efi.jpg There is over $3000 worth of intake manifold, injectors, fuel rails and other parts there. My complete Marine Intake conversion cost $975US, and the intake/rails/injectors cost $750. I only needed to buy a couple of fuel line couplers and intake gaskets. The kits even come with colour coded wires that match the GM original fuel injector wire harness.
The Marine Intake looks like the truck intake, except for the external fuel rails. This project was undertake with the idea of passing emmisions tests. The stock truck cruise control, throttle cables, air intakes, throttlebody all fit. Even air intakes and ALL superchargers mant for teh Vortec 305/350 will fit the Marine intake as it has teh same external dimensions as the L31 truck intake. the big difference is on teh inside, where the marine intake has MUCH more plenum volume, a smoother lower plenum floor and NO flow restrictions insid ethe intake. The stock L31 truck intake has all the injection,fuel pressure rgulator and feed hoses on the INSIDE of teh intake, all of this hurts flow.
the stock injectors have a limit of around 400 naturally aspirated hp, with larger injectors, taht is a thing of the past.

Sorry for the long post. I get really excited about Vortec 350 mods. My MArine Intake conversion is the 1st of its kind in North America and it was the 2nd running install in North America.

Goodluck with your LT1, dont rule out the LS1 or the LT4 for that matter. I am partial to teh LT4, with its red intake manifold and underrated power and high revving 6400 rpm rev limit, it was a good way to send end the GEn 2 engine run. The LT4 was the very last 4" bore and 3.48" stroke 350 to be used in any car.

Oh, before I sign off, I wanted to blab about MAFS. The Impala SS used a smaller (3.0")MAFS than the LT1's in the F-bodies. The Fbodies used the aluminum bodied 75mm(3.5") MAFS all the way into 2002. This MAFS has 3 wires going to it. It uses a divorced IAT sensor.
the 75mm MAFS was used on the 2001 LS6 Vette engine which was rated at 385 net hp, and also on the 02+ LS6 engine which was rated at 405 sae net hp. if you convert this 405 SAE NET hp over to gross hp, it comes out to ROUGHLY 508 hp. These stock 85mm MAFs are good out to beyond 600 gross hp.

In the 99+ GEN 3 engined (4.8, 5.3, 6.0L) trucks and the 2001+ Vettes, Gm switched to an 85mm plastic bodies MAFS which uses 5 wires as it includes and internal IAT(intake air temp) sensor.

here is a link showing what I am talking about and it even shows the MAFS frequency tables which must be inputted into the PCM for the swap.
http://www.ls1howto.com/index.php?article=25

I bought a brand new 85mm mAFS from a place in Florida for $40US shipped to my door in Canada. They are $400 Canadian from a dealership.

Again, sorry for the long post.
peace
Hog

Last edited by Hogg; 12-29-2006 at 01:27 PM.
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Old 01-01-2007, 01:41 PM
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one more question

How are the motor mounts different on an LT1 if at all?? And can i run a 700r4 tranny insted of the electronic version ?? or should i just dump the money into heads / cam and stick with the TH350 tranny?? Your opinions count!!
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Old 01-01-2007, 02:06 PM
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Some cars used the alternate bosses for the motor mount, but that means most LT1s are drilled in both locations. Otherwise, normal small block mounts work. An LT1 should bolt in anywhere an SBC was before and vice versa.

You can use any transmission you wish. If you're switching FROM a 4L60E, simply choose a PCM from a manual car, or have the PCM reprogrammed to not look for a tranny. I'm switching from a 4L60E in my Impala SS to a T56 six speed. I just need to remove the tranny from the equation and it assumes there is a manual back there.
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Old 01-08-2007, 12:59 AM
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now thats alot of info


i know the lt1 in my 94 carpice wagon MOVES to the point sometimes you gotta look behind you and remind yourself your driving a wagon
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