Modding Your TPI - 101
1986Z28
12-01-2008, 12:38 PM
This is a basic guideline for anyone that wants to squeeze some more power out of there TPI, without getting to serious with internals etc...
The Basics: A Tune Up
The first step before modifying any vehicle should be a complete tune-up. It is something most overlook when modifying there car, and thruthfully, how can you expect to get the most out of your new mods if something as simple as your spark plugs arnt working at the best, or fuel supply is starved because of a clogged fuel filter?
The Basics of a tune up where one should start would be the obvious:
-Spark Plugs
-Ignition Wires
-Distributor Cap and Rotor
-Air Filters
-Fuel Filters
-PCV valve
-Oil Change and new filter
Some of the more In-Detail things would be cleaning you Idle air control valve, and checking adjustment on the Throttle Position sensor (write up coming on how to do these 2 things)
As always I always suggest using higher grade parts rather than the standard grade stuff found at most jobber stores. If you plan on running a MSD 6A or 6AL ignition box sometime down the road, the plugs id reccomend for you are AC Delco's gapped at around .045" compared to the standard .035" for a SBC. Mainly because of the higher output from the MSD box, compared to stock output. For Ignition wires id reccomend looking at either some MSD's or Taylor's, both are bery high quality wires, my preferance is the MSD Super Conductor 8.5mm's. Stay away from such brands as Accel, they used to be number one in the game of ignition products, but thats no longer. Most products coming from them now, from what ive seen are of poor quality. MSD also makes a cap and rotor kit for the External coil GM EFI distributors. The PN on this kit if 8406, ive used this kit many times, high quality, and also has brass terminals.
As restrictive as air filters can be, they are however needed. So why not replace them with something higher flowing such as K&N's. Keep in mind, your not going to see any large gains from simply changing your air filters, but everything helps. While your changing them, Id also suggest pulling the filler section from the bumper and cutting the bottom of the filter bases off. This will get rid of the Restrictive baffles that GM installed to reduce the amount of noise made by the incoming air.
Now for what i would say is the most over looked compnent of a good tune-up. The fuel filter, even if the filter is slighty clogged, fuel flow to the engine is limited and can limit performance. I suggest changing your fuel filter every 2-3 oil changes.
And that brings us to the oil change, commonly overlooked, but it dosnt matter what you own, but you should be doing one on a regular basis. If you want to free up a little extra power, why not switch to a Full synthetic oil such as Mobil 1 or Royal Purple. I also suggest staying away from oil filter brands like FRAM, they use a high amount of cardboard in there filters. I personally run K&N oil filters, they are fairly inexpensive, and also feature a nut welded on the end for easy removal.
Ok, now that we have the tune up covered, we can move onto some mods!
The stock TPI air intake system is very restrictive, something that can help that include what i mentioned before(K&N filters, and modifying the air box base.) Some other things expecially for the MAF guys is to De-screen the MAF sensor. This involves simply removing the screens found at the front and rear of the MAF sensor to allow more air to flow through it. The next thing on the list, some say they are garbage, some same they work, most manufactures claim a gain of aorund 7hp, if you dont know already, im talking about a throttle body airfoil. They are advertised to help smooth out the incoming airflow going through the throttle body. They are cheap, and in myhonest opinion, for the price they are worth a shot.
Since your already getting air in better than before, the next place to start is obviously exhaust. Id suggest starting with a set of Headers. If your must be emissions legal, there are a few brands that allow you to keep air injection, Hooker being one. If emission legal isnt a big deal, i would suggest going with a set of Hooker shorty headers, hooker also makes a mathcing high flow Y-pipe. Some will says long tubes are the way to go, but thruthfully, they arnt needed on a slightly modded TPI engine, and the PITA your going to have with a exhaust system typically ways most to go with shorty's. There are many brands of high flow 3" cat backs available, Magnaflow recently released a full stainless kit, flowmaster also has there american thunder 3" kit. There is also some higher end brands such as Borla, but a typical cat-back from borla goes for around 800-900$.
A very common modifcation, if underdrive pulleys, they have been claimed up to 15 hp from reducing parasitic loss on the crank and alternator pulleys. Ive personally used a set, a felt a noticeable gain.
Now back to ignition again, I mentioned this before, but im a firm believer in MSD's capacitive dischard boxs, I personally run them on all of my vehicles, The biggest advantage is under 3000RPM(tpi systems make most of there power here) where the main benefit is multiple spark discharge. Basically whats its doing, is not only supply a stronger spark, but more of them, rather than firing the plug only once, it fires it multiple times rapidly, and is said to equal 5-10 degrees of total spark. By doing this, It burns the air/fuel misture more complete, creating more power, and lower emissions(i have personally seen the gains in fuel mileage.) Id also suggest going to a MSD blaster coil, its higher output, and cheaper than a stock replacement.
Finally, one of the cheapest things you can do(requires a fair bit of work though) is installing a AFPR(adjustable fuel pressure regulator) as engine air intake increases, most fuel is needed, and this is where this comes into play, by increasing pressure to the rails, your increasing the amount of fuel your engine is getting. Keeping in mind, it is very easy to supply to much fuel pressure, and over fuel the engine, typically 1-2 psi over the stock setting is more than enough for a slightly modded TPI engine.
The Basics: A Tune Up
The first step before modifying any vehicle should be a complete tune-up. It is something most overlook when modifying there car, and thruthfully, how can you expect to get the most out of your new mods if something as simple as your spark plugs arnt working at the best, or fuel supply is starved because of a clogged fuel filter?
The Basics of a tune up where one should start would be the obvious:
-Spark Plugs
-Ignition Wires
-Distributor Cap and Rotor
-Air Filters
-Fuel Filters
-PCV valve
-Oil Change and new filter
Some of the more In-Detail things would be cleaning you Idle air control valve, and checking adjustment on the Throttle Position sensor (write up coming on how to do these 2 things)
As always I always suggest using higher grade parts rather than the standard grade stuff found at most jobber stores. If you plan on running a MSD 6A or 6AL ignition box sometime down the road, the plugs id reccomend for you are AC Delco's gapped at around .045" compared to the standard .035" for a SBC. Mainly because of the higher output from the MSD box, compared to stock output. For Ignition wires id reccomend looking at either some MSD's or Taylor's, both are bery high quality wires, my preferance is the MSD Super Conductor 8.5mm's. Stay away from such brands as Accel, they used to be number one in the game of ignition products, but thats no longer. Most products coming from them now, from what ive seen are of poor quality. MSD also makes a cap and rotor kit for the External coil GM EFI distributors. The PN on this kit if 8406, ive used this kit many times, high quality, and also has brass terminals.
As restrictive as air filters can be, they are however needed. So why not replace them with something higher flowing such as K&N's. Keep in mind, your not going to see any large gains from simply changing your air filters, but everything helps. While your changing them, Id also suggest pulling the filler section from the bumper and cutting the bottom of the filter bases off. This will get rid of the Restrictive baffles that GM installed to reduce the amount of noise made by the incoming air.
Now for what i would say is the most over looked compnent of a good tune-up. The fuel filter, even if the filter is slighty clogged, fuel flow to the engine is limited and can limit performance. I suggest changing your fuel filter every 2-3 oil changes.
And that brings us to the oil change, commonly overlooked, but it dosnt matter what you own, but you should be doing one on a regular basis. If you want to free up a little extra power, why not switch to a Full synthetic oil such as Mobil 1 or Royal Purple. I also suggest staying away from oil filter brands like FRAM, they use a high amount of cardboard in there filters. I personally run K&N oil filters, they are fairly inexpensive, and also feature a nut welded on the end for easy removal.
Ok, now that we have the tune up covered, we can move onto some mods!
The stock TPI air intake system is very restrictive, something that can help that include what i mentioned before(K&N filters, and modifying the air box base.) Some other things expecially for the MAF guys is to De-screen the MAF sensor. This involves simply removing the screens found at the front and rear of the MAF sensor to allow more air to flow through it. The next thing on the list, some say they are garbage, some same they work, most manufactures claim a gain of aorund 7hp, if you dont know already, im talking about a throttle body airfoil. They are advertised to help smooth out the incoming airflow going through the throttle body. They are cheap, and in myhonest opinion, for the price they are worth a shot.
Since your already getting air in better than before, the next place to start is obviously exhaust. Id suggest starting with a set of Headers. If your must be emissions legal, there are a few brands that allow you to keep air injection, Hooker being one. If emission legal isnt a big deal, i would suggest going with a set of Hooker shorty headers, hooker also makes a mathcing high flow Y-pipe. Some will says long tubes are the way to go, but thruthfully, they arnt needed on a slightly modded TPI engine, and the PITA your going to have with a exhaust system typically ways most to go with shorty's. There are many brands of high flow 3" cat backs available, Magnaflow recently released a full stainless kit, flowmaster also has there american thunder 3" kit. There is also some higher end brands such as Borla, but a typical cat-back from borla goes for around 800-900$.
A very common modifcation, if underdrive pulleys, they have been claimed up to 15 hp from reducing parasitic loss on the crank and alternator pulleys. Ive personally used a set, a felt a noticeable gain.
Now back to ignition again, I mentioned this before, but im a firm believer in MSD's capacitive dischard boxs, I personally run them on all of my vehicles, The biggest advantage is under 3000RPM(tpi systems make most of there power here) where the main benefit is multiple spark discharge. Basically whats its doing, is not only supply a stronger spark, but more of them, rather than firing the plug only once, it fires it multiple times rapidly, and is said to equal 5-10 degrees of total spark. By doing this, It burns the air/fuel misture more complete, creating more power, and lower emissions(i have personally seen the gains in fuel mileage.) Id also suggest going to a MSD blaster coil, its higher output, and cheaper than a stock replacement.
Finally, one of the cheapest things you can do(requires a fair bit of work though) is installing a AFPR(adjustable fuel pressure regulator) as engine air intake increases, most fuel is needed, and this is where this comes into play, by increasing pressure to the rails, your increasing the amount of fuel your engine is getting. Keeping in mind, it is very easy to supply to much fuel pressure, and over fuel the engine, typically 1-2 psi over the stock setting is more than enough for a slightly modded TPI engine.
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