Fiero LT1 Frequently Asked Questions

Fiero LT1 Frequently Asked Questions redlt1.gif

Table of Contents

  1. What’s the difference between the ’93s and ’94s?
  2. What’s the difference between the ’94s and ’95s?
  3. What’s the difference between the ’95s and ’96s?
  4. What’s the difference between the ’96s and ’97s?
  5. What’s the difference between the 97′s and 98′s?
  6. What’s the difference between the LT1 and its predecessor the L98?
  7. What’s the difference between the F-body LT1 and that in the Corvette?
  8. Is there anything I should be concerned about when flushing my radiator on an LT1?
  9. What is the firing sequence for the LT1?
  10. What is OBDII and can I modify my car with aftermarket parts?
  11. What’s the size of the LT1 throttle body and can I use a larger one?
  12. Why and how should I bypass the throttle body coolant lines?
  13. Why and how should I bypass the EGR valve/line?
  14. Why and how should I relocate my idle air temperature (IAT) sensor?
  15. What temperature is the stock thermostat and can I go lower?
  16. What performance “chips/programs” are available?
  17. Can I keep the stock thermostat after installing a performance chip?
  18. What fuel pressure setting will give me the best performance?
  19. What spark plugs are available for the LT1?
  20. Why has my car developed a bad hesitation problem (Optispark)?
  21. Why does my car have a slight stumble upon slow acceleration?
  22. Should I use self-aligning or non-self-aligning rockers?
  23. What aftermarket camshafts are available for the LT1?
  24. What’s that knocking noise when the engine is cold?
  25. How can I display the error codes from a Service Engine Light?
  26. Do I need to keep two computers?
  27. What is “Computer Piggybacking” ?
  28. Why did you choose Archie’s basic kit?
  29. Why do I need to move the engine/tranny to the left?
  30. Why do I need custom axles?
  31. Why do I need to notch (cut) the frame rails?
  32. Where is the notch located?
  33. What kind of gas mileage are you getting?
  34. Where can I find an LT1 motor?
  35. Besides the Camaros and Corvettes, what other cars had the LT1 engine?
  36. Do you have emissions tests where you live, and if so, does your car pass?
  37. How much power/torque does it have?
  38. Was the wiring harness a nightmare?
  39. Is the stock Fiero fuel pump up to the pressure/volume demands of this motor?
  40. Was the exhaust system a pain?
  41. Do you have a list of part numbers for the most commonly used GM items?

What’s the difference between the ’93s and ’94s?

The Main mechanical differences included a change from Multi-port to Sequential Fuel Injection (including an upgrade from 22 lb. fuel injectors up to 24lb. injectors), a change from Speed Density to Mass Air Flow (MAF) Control, the EPROM computer chip became soldered to the main computer board making it no longer removable, a change from single wire O2 sensors to 3 wire heated ones, the air openings on the exhaust manifolds are in a different place, and a dampner was added to the yoke assembly on the prop shaft (this actually went into production in the later ’93 LT1 cars).


What’s the difference between the ’94s and ’95s?

No major changes were made to the ’95 cars.The camshaft, distributor, and drive mechanisms for the distributor and water pump are different. The changes were basically made to improve the distributor by adding a ventilation system that is connected to the air intake. This draws air through the distributor to eliminate moisture buildup in the optical mechanism. With the low distributor mounting, plus the water pump being directly overhead, there was a tendency for moisture and coolant to seep into the distributor leading to the infamous “optispark” problems. The drive mechanism between the cam, distributor, and water pump was also improved.


What’s the difference between the ’95s and ’96s?

Low-resistance ignition wires were designed to improve idle quality and cold-start performance. A redesigned ignition coil has half of the primary inductance as the previous coil allowing the primary current to “pour in” much quicker for muchimproved output at higher RPMs. Revised pistons used a new positive-twist top ring that improved the piston-to-cylinder seal and reduced blow-by emissions at high speeds.The pushrods were no longer hardened as they were in previous years. The exhaust manifolds got tri-layered stainless steel gaskets for improved durability and reduced leaks.The biggest change was that of the on-board computer. 1996 was the first year of OBD-II ECM technology to better diagnoses engine problems. This was good for reliability, but bad for some modifications in that some heavy modifications to the engine could result in a Service Engine Soon light. OBD-II also required oxygen sensors just beforeand after the catalytic converter for before and after measurements. Although the ones after the converter really only measure the performance of those before it.


What’s the difference between the ’96s and ’97s?

No major mechanical changes.


What’s the difference between the 97′s and 98′s?

1998 brought the new switch of denominations from LT1 to LS1. The LS1 in the Z28 and T/A was rated at 305 HP @ 5,200 RPM, while torque is 335 ft-lbs @ 4,000 RPM.


What’s the difference between the LT1 and its predecessor the L98?

There is a recent SAE paper that compares and contrasts the two engines. It discusses history, cooling, lubrication, breathing, ignition, etc. The name of the paper is “New Generation Small Block V8 Engine,” SAE paper 920673, by Anil Kulkarni of GM. It can be obtained from the SAE by calling 412-776-4841.


What’s the difference between the F-body LT1 and that in the Corvette?

The engines are exactly the same with the exception of the air intake and the exhaust. Also the Corvettes have two knock sensors and 4-bolt mains compared to 1 knock sensor and 2-bolt mains on the F-Bodies, respectively. The Corvette has a larger/wider air intake box plus a dual muffler/exhaust which accounts for the additional 25hp. The F-Bodies are also supposed to have a redesigned oil pan as the Vette one doesn’t fit with the F-body cross-member. Also, the fuel fittings on the F-body’sintake exit towards the left (driver’s) side of the engine. On the Corvette they are on the right (passenger) of the engine.


Is there anything I should be concerned about when flushing my radiator on a LT1?

Yes, there are several things. First, you should take great care in keeping any coolant off of your OptiSpark which is located in the front bottom portion of the engine. This is especially important on 93 and 94 models, as they are not properly vented. Water will destroy your Optispark. When filling your cooling system back up, make sure that you bleed the cooling system by opening to 2 valves on top of your engine. This will allow for air-bubbles to escape. Once again though, be careful as the valves are located directly above the Optispark.


What is the firing sequence for the LT1?

1-8-4-3-6-5-7-2   The cylinders are numbered the same as in previous years.


What is OBD-II and can I modify my car with aftermarket part

OBD-II or On-Board-Diagnostics Second Generation is a revised PCM program that monitors that catalytic converter process by monitoring 2 additional sensors behind the cat converters. It is assumed that if the readings detect higher emissions, then the catalyst process is no longer functioning properly. For obvious reasons, any radical mod’s (CAM’s, etc) should be checked out with the manufacturer prior to installation to determine if this will cause any error codes. Even with the older OBDI, I have had the CHECK ENGINE light flash when I”step” on it. This is because the Granetelli MAF and the K&NFilter that allow a lot of air to be swallowed before the ECM can register it.


What’s the size of the LT1 throttle body and can I use a larger one?

A stock throttle body inlet is 48mm in diameter. The matching inlet on the intake manifold which it’s attached to is about 52mm. Therefore, you can safely buy a 52mm one (like that from TPIS) and bolt it on in place of the stock one without any other modifications. Anything larger (like the 58mm from Lingenfelter) would require the intake manifold to be bored out to handle in the increased volume of air. The larger throttle bodies are not physically larger, they’ve just been bored out making the openings larger.

The additional amount of HP from the 52mm throttle body is questionable. Some reports show little or no increase, yet others claim up to 10 more HP. And some air foils (to smooth the flow through the throttle body) claim to get another 5 HP. But even that, is questionable. A 58mm throttle body (in conjunction with the bored intake manifold) might provide a larger increase in HP, but once again, results usually vary.


Why and how should I bypass the throttle body coolant lines?

A small amount of coolant is passing through the small hoses connecting to the throttle body. The main reason is so that during the winter months, the higher temperature of the coolant will keep the throttle body warmer thereby preventing icing. That’s where the problem lies during the other months. By warming up the throttle body, you’re warming up all of the air passing into the engine and thus losing some power (since cooler, denser air makes more power). It is also believed that during the hot, summer months, the coolant pass-through works to cool off the throttle body. So you must be careful when bypassing this so as not to loose it’s benefits. Here, in Wisconsin, I left it alone. I can use the warm air. But if you live farther south, like Texas, I would experiment without it. Who knows you might gain .001 horsepower. 
To do the bypass, first remove the small hose going into the throttle body on the driver side. You will probably have to remove the rubber intake elbow and black alternator brace. Make sure you have some rags handy to catch any coolant that my drip out. On the passenger side of the throttle body there are three hoses. Remove the lower one (which is very short and has a 90 degree turn to connect to a metal intake manifold hose). You may have to remove the other two hoses along with the sensors to get better access to the clamp. Then pull the disconnected driver side hose over, and connect it to the metal intake manifold hose from which you just disconnected on the passenger side 90 degree-turn hose. Hold onto that 90 degree hose in case you need it in the future.


Why and how should I bypass the EGR valve/line?

The EGR re-routes some of the exhaust gases back into the intake/combustion chamber. This is basically done to reduce emissions. Blocking it off will increase temperature of theintake since the gases fed back through the EGR are very hot. Lower intake temperature produces more power, but the amount of gases that are passed through the EGR is VERY minimal and probably won’t result in much (if any) performance gain. The drawback is increased emissions.

If you look at the back of the passenger side of the intake manifold. You will see a tube that runs up to the manifold from the exhaust manifold. Take the tube off, pull it back,and look at it. You will see a two bolt pattern with a hole in the middle. Make some kind of plate to block the hole and guided on the bolt hole. You can make the plate out of any piece of scrap metal (sheet metal is fine). Put the tube back on with the plate in place.


Why and how should I relocate my idle air temperature (IAT) sensor?

The stock position of the IAT sensor (in the rubber intake elbow just before the throttle body) causes it to pick up a lot of intake manifold heat. This can be an extra 10 degrees F at highway speeds and 30 degrees F (or more) at idle. This causes the computer to retard the timing (zapping power) and causes the engine to run overly rich (since the MAF thinks there’s more air going through it than there really is due to artificially high temperatures). By moving the IAT towards the air filter (away from the hot manifold), the ECM will get a more accurate reading of the actual intake temperature and will properly adjust the timing and fuel/air ratio. There’s no need to worry about the air heating up more as it passes beyond the new location of the IAT since at wide open throttle, it takes the air 1/1000 of a second to travel from the air filter into the engine.
First, remove the IAT sensor from the bend in the rubber intake elbow. Then plug up the hole on the elbow with something. The site you relocate the IAT to will depend on what air intake (stock or after-market) you have. You want it as close to (if not, right in) the air filter. Snip the sensor wires first, as you can splice in lengths of wire after the sensor is in its new location. On a stock air box, you can drill a hole into the back of the box. On after-market intakes, try drilling a hole at the bottom of the air filter itself (works best on K+N conical filters) or on the pipe/tube to which the filter is connected. Either way, make sure the hole is placed in location which sees the air AFTER it passes through the air filter (otherwise debris may ruin the sensor). Then, insert the sensor into the hole. After that, just splice wires to reconnect the sensor, solder the connections and protect with electrical tape or heat shrink-wrap.

I relocated my IAT, but only because the stock location on the rubber below interfered with the Fiero shock tower. So I moved it to the inside of the curve. Still works good and the wire reached just fine.


What temperature is the stock thermostat and can I go lower?

Stock on the 4th generation cars is a 180 degree thermostat. This should be good enough for any but the most seriously modified car. Although, you can go down to 170 or even 160. Hypertech sells a 160 which is supposed to be combined with their performance chips/programmers. And contrary to some opinions, the vehicle will not drop out of closed loop with 160 degree thermostat since that depends primarily on O2 sensor temperature, not engine temperature.


What performance “chips/programs” are available?

For the 1993 cars, Hypertech, Jet Technologies, Z Industries and Superchips make replacement chips. HP increases vary from 15 up to 30. However, in 1994 and after, chips are soldered into the on-board computer and can’t be removed. Hypertech gets around this with their Power Programmer, a hand-held “computer” which plugs into the PCM module under the driver’s side dash, and reprograms the stock chip. Performance gains are almost the same as replacing the chip. The programmer costs about $300, considerably more than the $150 – $200 you’d expect to pay for a replacement chip.

The Hypertech Program increases redline and shift points (on auto trannies) by about 500 RPM over stock, and it improves the fuel and timing curves.The cooling fans are forced to coming on at lower temperatures. Any type of speed limiter will be overridden. It can also adjust the speedometer for changes to aftermarket gears (like a 3.73).
However, it doesn’t modify the partial throttle shift points on cars with automatic trannies. Thus, even with the programmer, partial throttle shifts will still occur at higher RPMs than with the stock gearing. But most companies can create a custom chip or program to overcome this.

The Programmer can also be sent back to Hypertech to be reprogrammed to take advantage of modifications like headers, camshafts, and superchargers. One other thing to remember is to run 92+ octane fuel with the chip/programmer. Otherwise the engine is probably going to knock due to the timing change

Besides HyperTech programmers, there are other Do-It-Yourself tools that will allow you to do your own tunning. Many people think these are better since Hypertech charges you extra for every little change you want to make. Also they lock your programmer to one car only by VIN number. Some of these tool are FREE! check’em out.

Scaning Tools:
EFILive
FreeScan
PCMComm

PCM Reprogramming Tools:
LT1 Edit

For any type of DYI programming, you’ll need a cable to connect your laptop computer to the car’s ECM. AKM Electronics has you covered. Andrew is great, and he can help you select the type of cable you need depending on what kind of ECM you have.


Can I keep the stock thermostat after installing a performance chip?

Yes, however you should do a little research first. Namely, find out if the new chip modifies the temperature at which the cooling fans come on and off. For instance, the Hypertech chip/program lowers the temperature at which the fans turn on and off. It turns the fans off at approximately 175 degrees F. This will a problem with the stock 180 thermostat because once the engine warms up enough to turn on the fans, the thermostat will cycle to bring the engine temperature down to 180 degrees F and keep it there. This could keep the temperature from getting down to 175 where Hypertech turns off the fans, and the fans could run continuously. This isn’t bad for the engine, but it is bad for the fans in that it will probably burn out the fan motors.


What fuel pressure setting will give me the best performance?

Stock settings are around 43 to 45 psi. The best (adjusted) pressure seems to be variable depending on your cars specific modifications. But even cars with similar mods react differently to pressure adjustments. Some people claim 47 to 49 psi is best, while others find a lower setting like 39 to 42 psi is best. From testing, it seems the computer will adjust itself to a fuel mix level that it is comfortable with. So even if you turn up the pressure to 53 psi, after a few wide open throttle runs, the computer will lean out with each successive run, bringing itself down close to levels as though you were running 44 psi. So while adjusting the fuel pressure may have some effect, the computer retains a great deal (not 100%) of control as it will adjust the fuel mix based on each run. So you need to make multiple wideopen throttle runs between adjust ments of pressure to ensure you get to final equilibrium with the computer. The best way to find what’s best for yourcar is trial and error.

NOTE: Yes, a healthy Fiero fuel pump should be all you need to drive the LT1 with factory injectors to a happy medium.


What spark plugs are available for the LT1?

Here’s cross reference of the different plugs along with the part numbers: Stock heat range:

AC Delco 41-906 (platinum, stock plug) 
AC Delco Rapidfire 3 
AC Delco R44LTS 
Accel 516 
Autolite 106 
Bosch HR9DPX 
Champion RS14YC 
Motorcraft AGRF42 
Nippondenso T16EPR-U 
NGK TR5 (.035 gap) 
NGK TR55 (.050 gap) 
NGK TR55VX (platinum version of the above)

Colder range:

AC Delco R42LTS 
Accel 514 
Autolite 104 
Bosch HR8DPX 
Champion RS9YC 
Motorcraft AGRF42 
Nippondenso T20EPR-U 
NGK BPR6EFS


Why has my car developed a bad hesitation problem (Optispark)?

First, check to your spark plugs wires and make sure none have come off. A few people have already experienced this problem. Then rule out any type of problem with the fuel system (injectors or pump) and air intake (loose clamp or hose). If those are okay, it’s most likely your Optispark system. It’s the pseudo-distributor of the distributor-less LT1 where all the spark plug wires connect into. If water gets in there, it’s as good as toast. Definitely head to your dealer to get it replaced as it will start eating your plugs and wires in no time if there’s something really wrong with it. A hesitation problem due to the Optispark will usually be noticed in certain RPM range. Most commonly, it is in the upper range (3500 – 5000 RPM). But it can certainly develop in the lower or mid ranges as well. You might even get some back-firing. The problem is most common on the 1993 and 1994 LT1s, as in 1995 a vacuum line was added from the intake manifold to the Optispark to draw moisture out of the unit. However, excessive water can cause even 1995 and later cars to develop the problem.

NOTE: This actually happened to me. I was flushing/burping my cooling system as specified by the GM service manual, using the bleeder on the goose neck. After all was done, I started backing out of my garage when it started stumbling and missing until it finally stalled. It did not start back up. Three days later, as I was contemplating the purchase of another “opti-crap”, when I had an idea… I loaded up my air compressor and turned it up to 80psi. A 5gal.tank was emptied into the distributor blowing through the vacuum hose. There is a trick to doing this and might only work with the 1995-up opties that have the vent tubes. Write me if you are interested in the details. But this cured the problem! Amazingly enough. I was lucky though. That distributor was as goodas dead.


Why does my car have a slight stumble upon slow acceleration?

If it usually occurs from idle when then engine is warm and you get a short backfiring just before shifts, then it’s probably the coil wire or the coil itself. If you notice the headlights flicker or flash at night when the car stumbles, it’s almost assured the coil and/or coil wire need replacement.


Should I use self-aligning or non-self-aligning rockers?

You can use either since the LT1 has screw in studs, but non-self-aligning rockers require guideplates. This means longer rocker studs are needed as well as hardened pushrods. And that means more money. But the advantage of the non-self-aligning ones is the reduced valve train noise.


What aftermarket camshafts are available for the LT1?

Please refer to the LT1 Cam Data installation page.



What’s that knocking noise when the engine is cold?

While the fuel injectors have a distinct tapping noise (usually under higher throttle), at a light load and low speed there seems to be “pistonslap” on some people’s cars. This occurs in some of the Vette LT1s as well. There doesn’t seem to be anything in the service manuals. Most dealers seem to acknowledge the problem and say it’s normal, which it seems to be. For some reason, the pistons shrink enough in the cold weather so as to “slap” around a little. Once the car warms up, the noise should go away


How can I display the error codes from a Service Engine Light?

According to the 1994 F-Carline Service Manual, page 6E-6 states in part:

“Although it is recommended that a diagnostic scan tool be used to read diagnostic trouble code(s), it may be possible to flash trouble codes on certain vehicles equipped witha 12 pin DLC connector.”

If your car does not have the 12 pin DLC connector, you may not be able to manually “flash” your trouble codes. The language “may be possible” appears to suggest that this method should work with most, if not all, 12 pin DLC equipped cars.

THE CONNECTOR

—————————-
|  1   2   3   4   5    6     |
|  7   8   9  10  11  12  |
—————————-

Pin 6 = Ground
5 = Diagnostic Terminal
2,12 = Serial data
1 = TCC (Torque Converter Clutch Solenoid)

DISPLAYING THE TROUBLE CODES

Some people with 94 models and on have had trouble using the following method, but it still won’t hurt to try it. Ground Pin 5, the diagnostic terminal (into Pin 6), with the ignition off – then turn the ignition to the on position without starting the engine will flash the “Service Engine Soon” light in the following sequence. flash, pause, flash-flash, long pause flash, pause,flash-flash,long pause flash, pause, flash-flash, long pause Following this “12″ code repeating three times will come any trouble codes stored, flashing each of them three times. If you do not see the “12″ flash three times, your diagnostic circuit could be defective. Otherwise you probably need a GM scantool.

Some vehicles will display stored trouble codes, then “12″ again, followed by energizing “most system controlled relays.” The fuel pump relay will not energize. The idle air control valve will fully extend to enable checking minimum idle speed.

FIELD SERVICE MODE

Starting the engine with pin 5 grounded will place the system in “Field Service Mode” Open loop will result in the Service Engine Soon light flashing more than twice per second. Closed loop will result in (1) Light flashing once per second, (2) Light staying off when running lean, and (3) Light staying on if running rich.

CLEARING THE TROUBLE CODES

Turn the keyswitch to the off position. To clear any trouble codes, disconnect the power feed for 30 seconds. If this is done at the battery, and your car stereo is equippedand programmed with a four digit pin code, you may have to re-enter that as well to use your stereo again. A better place to remove power is at the fuse.

NOTE: I personally was not able to jumper pin A & B like I used to with the Fiero ECM. Even though the LT1 ECM was reprogrammed as a 1994. I had no choice but to buy an Auto X-Ray XP240 better known as an OBDI EZLink scanner. It run me about $140 on sale. And I have to say… IT IS AWESOME. I highly recommend it to read those pesky codes. It also has real time monitoring capabilities for intermitent codes, PC interfacing and tells you in plain English what the problem is, not just the code. No more flashing lights for me!


TROUBLE CODES

13. Open circuit at left oxygen sensor
14. High temperature indicated at engine coolant temp. sensor
15. Low temperature indicated at engine coolant temp. sensor
16. Low voltage at battery
17. Circuit fault/error at camshaft position sensor
18-20. N/A
21. High voltage at throttle position sensor
22. Low voltage at throttle position sensor
23. Low temperature at intake air temperature sensor
24. Fault in vehicle speed sensor
25. High temperature at intake air temperature sensor
26-27. N/A
28. Fault in transmission pressure switch assembly
29-32. N/A
33. High voltage (low vacuum) at manifold pressure sensor
34. Low voltage (high vacuum) at manifold pressure sensor
35. Idle speed can not be set to desired RPM
36. 24X signal
37. Fault in torque converter clutch brake switch
38. N/A
39. Fault in torque converter clutch circuit
40. N/A
41. Fault in ignition control timing circuit
42. Error in ignition control
43. Fault in knock sensor circuit
44. Left oxygen sensor lean
45. Left oxygen sensor rich
46. PASS-Key II circuit
47-50. N/A
51. PROM error
52. N/A
53. High voltage at battery
54. Low voltage at fuel pump
55-57. N/A
58. High temperature in transmission fluid
59. Low temperature in transmission fluid
60. N/A
61. A/C performance
62. N/A
63. Right oxygen sensor open circuit
64. Right oxygen sensor lean
65. Right oxygen sensor rich
66. Low A/C refrigerant pressure
67. A/C refrigerant pressure circuit error
68. A/C compressor relay short circuit
69. A/C compressor relay open circuit
70. High A/C refrigerant pressure
71. Low temperature at A/C evaporator
72. Signal error at vehicle speed sensor
73. High temperature at A/C evaporator
74. N/A
75. EGR solenoid #1 error
76. EGR solenoid #2 error
77. EGR solenoid #3 error
78. N/A
79. Transmission fluid hot
80. Transmission slipping
81. N/A
82. 3X signal, ignition control error
83. N/A
84. CAGS open circuit (95′s and up only)
85. PROM error
86. Analog to digital converter error
87. EEPROM error
88-89. N/A
90. Torque converter clutch error
91-92. N/A
93. Pressure control solenoid Circuit current error
97. Voltage low in transmission system
98-99. Invalid PCM Program


Do I need to keep two computers?

It has been done. If you go with an aftermarket computer/harness solution, you might need to keep your Fiero ECM only to control your gauge cluster and such. This is called “PiggyBacking”. Some other solutions such as the new Accel’s EFI systems and others from Painless Wiring, might allow you get away with one unit. In my case, the 1995 LT1 ECM was reprogrammed as a 1994 unit and a custom marriage between the Fiero Harness and the LT1 harness allowed me to just replace the Fiero ECM and Fiero engine harness. It was truly a plug-n-play scenario.


What is Computer Piggybacking?

See above. FAQ #26


Why did you choose Archie’s basic kit?

Why Archie’s? Gee, I don’t know… Could it be because of the excellent quality of his products? Could it be because of the fact there are well over 100 Fieros out there with thousands of miles on Archie’s swaps. Or maybe because of the outstanding customer support he always provides? Why the the basic vs. the deluxe? Only because of a problem with the accounting department (my pocket). Otherwise, I would’ve gotten the whole thing at once. Saves a lot of headaches I tell you.


Why do I need to move the engine/tranny to the left?

One of reasons why the LT1 sits much lower than other SBCs is because the distributor got moved to the front of the engine. This added a few inches to the front of the block thus necesitating the move of the entire assembly little over 2″ to the left.


Why do I need custom axles?

Because of the above, the left axle becomes about 2″ shorter and the right about 2″ longer. Archie’s axles are hardened steel to the proper case depth. This is VERY important!


Why do I need to notch (cut) the frame rails?

When you move the engine/tranny assembly over, you will soon find out that the tail of the Fiero transmission will not clear the inner edge of the left frame rail. A minor cut is required to make room for it. The same applies to the harmonic balancer pulley (HBP). You need just enough clearance from the right frame rail also. If you use the LT1′s R-134a A/C compressor like I did, you might have to take that notch a little farther towards the front of the car to clear it.
NOTE: Please be advised that this frame modifications ARE NOT necessary if you use a “standard” Small Block Chevy (SBC). Only with the LT1, because of the reasons explained in FAQ #29 and FAQ #30 .


Where are the notches located?

One took out half of the left frame rail. Did not cut through the outer edge of the rail. On the right, same thing, except went forward farther to make room for the A/C compressor. Another cut through the right wheel well was done only to facilitate the installation of the water pump which, by the way, does not protrude out into the wheel well like you would see on the standard SBC swaps.


What kind of gas mileage are you getting?

With the few tests I have conducted so far using different driving styles, I can report the following:

Style CTY HWY
Normal 18 25
Spirited 14 21
Average 16 23


Where can I find an LT1 motor?

You can find LT1′s pretty much all over the country in junk/bone yards. Most of them are pretty good about it and will give you the LT1 fully dressed. Meaning all accessories, harness and brains. Some might even come with the 6 speed tranny which will be useless to you, but worth some money still. You can check hpsalvage.com and scott.net/~bgraham for these. You can also find them as new assemblies. Look for places like Street and Performance out of Mena Arkansas, Fuel Injection Specialties in St. Antonio, TX and so forth. I really don’t know if you can get the short block directly from GM anymore, but you can check gmgoodwrench.com. These would be the very expensive option however, since you would have to buy all the components separate.


Besides the Camaros and Corvettes, what other cars had the LT1 engine?

Really all Y, B and D body and F-Body post 1992 had it. Like Corvette, Camaro Z28, Firebird, Impala SS and Caprice (9C1 package for Police only), Roadmaster and Fleetwood.


Do you have emissions tests where you live, and if so, does your car pass?

Here in Wisconsin we have the dyno type of emission testing. And it passes with flying colors. I kept all the emission components by the way.


How much power/torque does it have?

Power and torque are very dependent on the year and model of car your engine comes from. All are different. Mine produces 295hp 325ft-lb @ 4500rpm in stock form.


Was the wiring harness a nightmare?

It would’ve been. My wiring is a custom made marriage between the Fiero harness and the LT1 harness done by Fuel Injection Specialties. They also reprogrammed the LT1 computer to match the gear ratio of the Getrag, tire size and also eliminated the dreaded VATS system for me (which can leave you stranded anywhere). It was expensive but well worth it! If you do it yourself, YES, It will be a royal nightmare!


Is the stock Fiero fuel pump up to the pressure/volume demands of this motor?

A healthy Fiero pump puts out little over 40psi which is just fine for a stock LT1. If you use a higher poundage injectors or switch to a variable pressure regulator for increase performance, then you might need to get an extenal push type pump.


Was the exhaust system a pain?

It was for me. But only because I’d never done anything like it before and had no welding experience what so ever. Also because I decided to use 2.5″ steel pipe where 2″ would’ve suffice. The increase in diameter makes every turn that much difficult and it takes away precious real state. A stock LT1, with a 2.5″ exhaust sytem will not give you any more than what a 2″ would. Why do it then? I did not want to do this twice, and a modified LT1 can take advantage of the extra breathing. Plans are to do a head swap and cam installation soon, with a final goal of turning the 350 into a 383 displacement engine. Am I crazy? You bet!


Do you have a list of part numbers for the most commonly used GM items?

Sure. Here they are.

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