Looking for advice on putting Tuned Port Injection on my 79 L82
01-16-2012, 12:16 PM
#1
Le Mans Master
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Looking for advice on putting Tuned Port Injection on my 79 L82
I'm planning on modifying my stock 79 L82 with the aim of getting the most fuel efficient 325-350 horsepower motor I can.
To increase driveability, fuel efficiency and power I was planning on using a 90-92 TPI system. I understand that the speed density system is preferable to the mass air flow TPI due to space concerns under the hood of the C3 Corvette, but it is also less tolerant of changes to the TPI system. Should I look at using a Megasquirt system instead or in addition to the TPI for this reason?
I'm told that the factory TPI motors only rev to about 4500 rpm. My L82 revs to 6000 nicely and with the gearing I'm going to have in the car (3.70 rear end, keisler five speed with 3.37 first) I want my modified motor to produce peak power around 5400 rpm and to rev to 6000. I know the long narrow intake runners in the stock TPI system are the reason stock TPI motors are low reving, low speed torque motors. I don't need low speed torque with my gears, is there an aftermarket TPI runner system that has shorter wider runners that will be fuel efficient and suitable for my horsepower and rpm goals?
Alternatively would it be possible and preferable to get a dual plane intake well matched to my performance goals and drill holes in the intake runners for the injectors and mount the throttle body where the carb would normally go? Maintaining the stock hood is a must so anything that would rule that out is a deal breaker.
I'm planning on using TPI with one of the following set of Vortech heads:
http://www.racingheadservice.com/Inf...rtec-Heads.asp
Both heads have 170cc intake runners and 64cc combustion chambers which if I remember correctly will bring my stock L82 compression ratio up to about 10 to 1. They are also dual pattern intake so if I understand that correctly can use either Vortech or non-Vortech intakes. RHS says the heads with the 1.94 intake and 1.50 exhaust can make up to 325 horsepower which sounds ideal if I actually can get that much out of them. My husband says the 2.02/1.60 RHS vortech head won't be any less fuel efficient than the small valve vortech at that power level. I thought the small valve vortech should maintain a higher flow velocity and thus be more fuel efficient - is that the case?
I've been studying cam shaft selection in motors people have producing 325-350 horsepower. Am I correct in assuming that the most fuel efficient cam for a 325-350 horse motor is one that will produce at most that much horsepower in a
350cid motor? Does the following sound like a good cam to produce 325-350 hp while also being fuel efficient?
http://www.lunatipower.com/Product.aspx?id=1983&gid=287
To increase driveability, fuel efficiency and power I was planning on using a 90-92 TPI system. I understand that the speed density system is preferable to the mass air flow TPI due to space concerns under the hood of the C3 Corvette, but it is also less tolerant of changes to the TPI system. Should I look at using a Megasquirt system instead or in addition to the TPI for this reason?
I'm told that the factory TPI motors only rev to about 4500 rpm. My L82 revs to 6000 nicely and with the gearing I'm going to have in the car (3.70 rear end, keisler five speed with 3.37 first) I want my modified motor to produce peak power around 5400 rpm and to rev to 6000. I know the long narrow intake runners in the stock TPI system are the reason stock TPI motors are low reving, low speed torque motors. I don't need low speed torque with my gears, is there an aftermarket TPI runner system that has shorter wider runners that will be fuel efficient and suitable for my horsepower and rpm goals?
Alternatively would it be possible and preferable to get a dual plane intake well matched to my performance goals and drill holes in the intake runners for the injectors and mount the throttle body where the carb would normally go? Maintaining the stock hood is a must so anything that would rule that out is a deal breaker.
I'm planning on using TPI with one of the following set of Vortech heads:
http://www.racingheadservice.com/Inf...rtec-Heads.asp
Both heads have 170cc intake runners and 64cc combustion chambers which if I remember correctly will bring my stock L82 compression ratio up to about 10 to 1. They are also dual pattern intake so if I understand that correctly can use either Vortech or non-Vortech intakes. RHS says the heads with the 1.94 intake and 1.50 exhaust can make up to 325 horsepower which sounds ideal if I actually can get that much out of them. My husband says the 2.02/1.60 RHS vortech head won't be any less fuel efficient than the small valve vortech at that power level. I thought the small valve vortech should maintain a higher flow velocity and thus be more fuel efficient - is that the case?
I've been studying cam shaft selection in motors people have producing 325-350 horsepower. Am I correct in assuming that the most fuel efficient cam for a 325-350 horse motor is one that will produce at most that much horsepower in a
350cid motor? Does the following sound like a good cam to produce 325-350 hp while also being fuel efficient?
http://www.lunatipower.com/Product.aspx?id=1983&gid=287
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NewbVetteGuy (08-15-2016)
01-16-2012, 01:32 PM
#2
Team Owner
It's true that the L98 motors don't rev too high and that power is made down in the 3000 RPM range. But with careful tuning and port-matching, the L98 can rev to over 5000 RPM but you should expect to see power fall off dramatically at that level.
What ECM are you going to run? You will need most of the wiring harness from a donor C4 to connect all the sensors to make sure the ECM will work. Also, the TPI system needs a good 40-45psi fuel pressure to run. There needs to be a fuel return line too (think the later C3's have that).
Why not look at aftermarket FI systems? Holley has a new system that replaces the stock Quadrajet and includes all of the wiring and comes with an ECM. The system is pretty much is self-learning and doesn't require tuning, just install and start driving. They have 4BBL TBI units that will support 500HP and more.
Look here: http://www.holley.com/division/Holleyefi.asp#95
Using a system like this allows you to use some carb intake manifolds that will fit under the C3 hood. But keep in mind that some of the hi-rise manifolds that will provide power and torque over the stock L82 manifold may cause hood issues.
Have you looked at heads from other vendors? Edelbrock, TrickFlow, Dart, and AFR should have what you need. Cam selection is also going to be very important along with the valvetrain. Look for roller rockers from Crane or Harlan-Sharp.
What ECM are you going to run? You will need most of the wiring harness from a donor C4 to connect all the sensors to make sure the ECM will work. Also, the TPI system needs a good 40-45psi fuel pressure to run. There needs to be a fuel return line too (think the later C3's have that).
Why not look at aftermarket FI systems? Holley has a new system that replaces the stock Quadrajet and includes all of the wiring and comes with an ECM. The system is pretty much is self-learning and doesn't require tuning, just install and start driving. They have 4BBL TBI units that will support 500HP and more.
Look here: http://www.holley.com/division/Holleyefi.asp#95
Using a system like this allows you to use some carb intake manifolds that will fit under the C3 hood. But keep in mind that some of the hi-rise manifolds that will provide power and torque over the stock L82 manifold may cause hood issues.
Have you looked at heads from other vendors? Edelbrock, TrickFlow, Dart, and AFR should have what you need. Cam selection is also going to be very important along with the valvetrain. Look for roller rockers from Crane or Harlan-Sharp.
01-16-2012, 01:57 PM
#3
Le Mans Master
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It's true that the L98 motors don't rev too high and that power is made down in the 3000 RPM range. But with careful tuning and port-matching, the L98 can rev to over 5000 RPM but you should expect to see power fall off dramatically at that level.
What ECM are you going to run? You will need most of the wiring harness from a donor C4 to connect all the sensors to make sure the ECM will work. Also, the TPI system needs a good 40-45psi fuel pressure to run. There needs to be a fuel return line too (think the later C3's have that).
Why not look at aftermarket FI systems? Holley has a new system that replaces the stock Quadrajet and includes all of the wiring and comes with an ECM. The system is pretty much is self-learning and doesn't require tuning, just install and start driving. They have 4BBL TBI units that will support 500HP and more.
Look here: http://www.holley.com/division/Holleyefi.asp#95
Using a system like this allows you to use some carb intake manifolds that will fit under the C3 hood. But keep in mind that some of the hi-rise manifolds that will provide power and torque over the stock L82 manifold may cause hood issues.
Have you looked at heads from other vendors? Edelbrock, TrickFlow, Dart, and AFR should have what you need. Cam selection is also going to be very important along with the valvetrain. Look for roller rockers from Crane or Harlan-Sharp.
What ECM are you going to run? You will need most of the wiring harness from a donor C4 to connect all the sensors to make sure the ECM will work. Also, the TPI system needs a good 40-45psi fuel pressure to run. There needs to be a fuel return line too (think the later C3's have that).
Why not look at aftermarket FI systems? Holley has a new system that replaces the stock Quadrajet and includes all of the wiring and comes with an ECM. The system is pretty much is self-learning and doesn't require tuning, just install and start driving. They have 4BBL TBI units that will support 500HP and more.
Look here: http://www.holley.com/division/Holleyefi.asp#95
Using a system like this allows you to use some carb intake manifolds that will fit under the C3 hood. But keep in mind that some of the hi-rise manifolds that will provide power and torque over the stock L82 manifold may cause hood issues.
Have you looked at heads from other vendors? Edelbrock, TrickFlow, Dart, and AFR should have what you need. Cam selection is also going to be very important along with the valvetrain. Look for roller rockers from Crane or Harlan-Sharp.
I haven't really considered anything other than the vortech heads because fuel efficiency is a major goal of this build, I understand that they are amongst the best designs for fuel efficiency and I don't want any parts tuned to build more than 325-350 hp for that reason. From what I've read it seems the vortech heads are the best bet from a fuel economy point of view and ditto for the TPI system. From what I can tell it appears that a head with 170 cc intake runner would produce up to 325-350 hp while maximizing port velocity for best fuel economy. I don't for example want a head with a 190cc intake runner on the theory that I'll be looking for more horsepower down the road - I won't be.
01-16-2012, 02:25 PM
#4
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I was planning on using the stock TPI ECM if it will work, if not would the Megasquirt be a good idea? I haven't considered aftermarket fuel injection because the cost is so high, I figure I can get a complete TPI system and harness from a wrecker for a fraction of what something like the Holley EFI will be.
I haven't really considered anything other than the vortech heads because fuel efficiency is a major goal of this build, I understand that they are amongst the best designs for fuel efficiency and I don't want any parts tuned to build more than 325-350 hp for that reason. From what I've read it seems the vortech heads are the best bet from a fuel economy point of view and ditto for the TPI system. From what I can tell it appears that a head with 170 cc intake runner would produce up to 325-350 hp while maximizing port velocity for best fuel economy. I don't for example want a head with a 190cc intake runner on the theory that I'll be looking for more horsepower down the road - I won't be.
I haven't really considered anything other than the vortech heads because fuel efficiency is a major goal of this build, I understand that they are amongst the best designs for fuel efficiency and I don't want any parts tuned to build more than 325-350 hp for that reason. From what I've read it seems the vortech heads are the best bet from a fuel economy point of view and ditto for the TPI system. From what I can tell it appears that a head with 170 cc intake runner would produce up to 325-350 hp while maximizing port velocity for best fuel economy. I don't for example want a head with a 190cc intake runner on the theory that I'll be looking for more horsepower down the road - I won't be.
I hear the learning curve on tuning a MS isn't that bad either, and most shops that do any tuning could probably take care of you.
01-16-2012, 06:16 PM
#5
How about a converted LT1 intake instead of the TPI? Sure wouldn't have hood clearance trouble or run out of breath too early. I also have the setup that I could let go of.
I had a 79 L82 back in the early 90's. I wanted a TPI on it - I thought it would have looked really cool in there. Back then I could only dream of such things - it would have been crazy expensive and DiY tuning has come a long way.
I had a 79 L82 back in the early 90's. I wanted a TPI on it - I thought it would have looked really cool in there. Back then I could only dream of such things - it would have been crazy expensive and DiY tuning has come a long way.
01-16-2012, 06:50 PM
#6
Le Mans Master
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How about a converted LT1 intake instead of the TPI? Sure wouldn't have hood clearance trouble or run out of breath too early. I also have the setup that I could let go of.
I had a 79 L82 back in the early 90's. I wanted a TPI on it - I thought it would have looked really cool in there. Back then I could only dream of such things - it would have been crazy expensive and DiY tuning has come a long way.
I had a 79 L82 back in the early 90's. I wanted a TPI on it - I thought it would have looked really cool in there. Back then I could only dream of such things - it would have been crazy expensive and DiY tuning has come a long way.
I know next to nothing about the LT1. I would consider the LT1 intake but I thought it wasn't compatible with the Vortech or early style SBC heads. What does it take to convert it to one of those?
What is the horsepower rating and at what RPM?
What is the rpm range where it produces best power?
What kind of distributor would it need and would that be compatible with my L82?
01-16-2012, 07:01 PM
#7
Safety Car
You could go to a FAST EZ-EFI system with it. They are not too expensive (<$1k), and they are self-tuning. 
The local Corvette shop in Austin put one in a C4, and within 20 miles the tune was complete. He also installed it in his C3 and loved it from the start.
Since you don't have all the instrument BS to deal with (mpg, avg. mileage, etc.) I think that is the perfect system for your application. It has a remote in the car you can use to tweak the tune as well. Fairly nice system.
http://www.compperformancegroupstore...stemEZIEFIKits
The local Corvette shop in Austin put one in a C4, and within 20 miles the tune was complete. He also installed it in his C3 and loved it from the start.
Since you don't have all the instrument BS to deal with (mpg, avg. mileage, etc.) I think that is the perfect system for your application. It has a remote in the car you can use to tweak the tune as well. Fairly nice system.
http://www.compperformancegroupstore...stemEZIEFIKits
01-16-2012, 07:32 PM
#8
Vortec heads limits your TPI style intake choices.
Either vortec HSR
http://www.summitracing.com/parts/WND-7542/
or the SDPC Vortec TPI base that takes stock or after market big tube runners
http://sdparts.com/category/sdpc-tpi-vortec-baseplate
They may have bolt patterns to suit both styles as shown on the aftermarket heads
in pic below
but require a raised runner SBC (non Vortec ) intake to match the tall narrow Vortec port
Reg SBC intake won't seal to Vortec heads
Either vortec HSR
http://www.summitracing.com/parts/WND-7542/
or the SDPC Vortec TPI base that takes stock or after market big tube runners
http://sdparts.com/category/sdpc-tpi-vortec-baseplate
in pic below
but require a raised runner SBC (non Vortec ) intake to match the tall narrow Vortec port
Reg SBC intake won't seal to Vortec heads
01-16-2012, 07:43 PM
#9
Le Mans Master
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Doesn't sound too bad at $900 but it doesn't include any sensors or injectors does it? From the description it doesn't sound like it controls ignition timing either with a knock sensor. I haven't priced out a used TPI system but I'm guessing one could get the whole works for $500 or so.
01-16-2012, 07:49 PM
#10
Le Mans Master
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Vortec heads limits your TPI style intake choices.
Either vortec HSR
http://www.summitracing.com/parts/WND-7542/
or the SDPC Vortec TPI base that takes stock or after market big tube runners
http://sdparts.com/category/sdpc-tpi-vortec-baseplate
They may have bolt patterns to suit both styles as shown on the aftermarket heads
in pic below
but require a raised runner SBC (non Vortec ) intake to match the tall narrow Vortec port
Either vortec HSR
http://www.summitracing.com/parts/WND-7542/
or the SDPC Vortec TPI base that takes stock or after market big tube runners
http://sdparts.com/category/sdpc-tpi-vortec-baseplate
They may have bolt patterns to suit both styles as shown on the aftermarket heads
in pic below
but require a raised runner SBC (non Vortec ) intake to match the tall narrow Vortec port
These raised runner SBC (non Vortec ) intakes, how do I know if an intake is a raised runner and where would I find such intakes?
01-16-2012, 08:01 PM
#11
Safety Car
Doesn't sound too bad at $900 but it doesn't include any sensors or injectors does it? From the description it doesn't sound like it controls ignition timing either with a knock sensor. I haven't priced out a used TPI system but I'm guessing one could get the whole works for $500 or so.
Self tuning ECU
Wideband oxygen sensor (with fitting and plug)
Handheld user interface
Tach adapter
Multi-Port wiring harness
Knock sensor should be in the motor, if not fairly cheap to get one.
01-16-2012, 08:20 PM
#12
Drifting
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tpi
Fast EFI is the way to go.The Vortec base is $400 add in the rest of the TPI stuff and you will be close to what a complete Fast system costs.I know you only want 325 to 350 horse,but the Fast system will support 600 horse power.
Last edited by steven mack; 01-16-2012 at 08:27 PM. Reason: add info
01-16-2012, 08:25 PM
#13
Le Mans Master
I like TPI a lot. Handsome setup. However, when it comes to upgrading TPI, big money for little over an extra 1,000 rpm kinda sucks. In three major components: plenum, runners, and base manifold, they get pricey for the performance version of them all together.
Although I have heard of some guys using a stock massaged plenum, performance base manifold and nicely siamesed runners pulling to 6,000 rpm. Not sure if they are making power up at that point.
Although I have heard of some guys using a stock massaged plenum, performance base manifold and nicely siamesed runners pulling to 6,000 rpm. Not sure if they are making power up at that point.
01-16-2012, 08:55 PM
#14
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Are you sure it can control spark timing? In the link you posted it doesn't say anything about it and the sensor kit they sell with it doesn't mention a knock sensor.
01-16-2012, 09:02 PM
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The Sroggins/dickey lower intake manifold with Vortech heads producing 300 hp sounds very close to my goal, very fuel efficient and perhaps a slightly larger cam than the stock L98 one would get me the extra 25-50 horsepower over what Scroggins/Dickey advertises.
01-16-2012, 09:03 PM
#16
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I like TPI a lot. Handsome setup. However, when it comes to upgrading TPI, big money for little over an extra 1,000 rpm kinda sucks. In three major components: plenum, runners, and base manifold, they get pricey for the performance version of them all together.
Although I have heard of some guys using a stock massaged plenum, performance base manifold and nicely siamesed runners pulling to 6,000 rpm. Not sure if they are making power up at that point.
Although I have heard of some guys using a stock massaged plenum, performance base manifold and nicely siamesed runners pulling to 6,000 rpm. Not sure if they are making power up at that point.
I think I'll contact scroggins/dickey and see what RPM their system produced that 300 hp at. If all it takes to turn 6000 is a $400 lower intake manifold added to the stock TPI that sounds like the way to go to me.
01-16-2012, 09:06 PM
#17
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01-16-2012, 09:11 PM
#18
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All long runner intakes flat line over 5K(ish )
Compare graphs in the link to operating ranges of long vs short runner intakes
http://xtremecarzone.com.au/index.php?showtopic=386
The no longer in production Super Ram ( will fit the SDPC Vortec base )
is best compromise for torque and Hp
01-16-2012, 09:30 PM
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Thanks for the links, Rodj, that's a big help. I realize that once the engine revs to 6000RPM it won't be making additional power, the reason I'm aiming for a horsepower peak at 5400 rpm and 6000 rpm capability is because I had a slightly modified 70 Torino with 4 barrel 351 Cleveland producing an estimated 325-350 hp at 5400 rpm and it was an absolute blast to drive. A drag racing article I read said that for best performance one should rev the motor 10% higher than the rpm where it produces peak power so I shifted at 6000 rpm. I'm looking to duplicate the Torino feeling in my Corvette and and it has (will have) similarly steep gears so I'm looking for a similar performing motor.
I don't think the Superram would be a good choice for me, I'm not trying to maximize horsepower with TPI, I'm trying to maximize fuel economy at the 325 hp level. From what I know any part that is tuned to produce more horsepower than that is going to be less efficient at 325 horse than a part that is tuned to make at most 325 hp.
I'll study the graphs you linked to.
I don't think the Superram would be a good choice for me, I'm not trying to maximize horsepower with TPI, I'm trying to maximize fuel economy at the 325 hp level. From what I know any part that is tuned to produce more horsepower than that is going to be less efficient at 325 horse than a part that is tuned to make at most 325 hp.
I'll study the graphs you linked to.
Last edited by Priya; 01-16-2012 at 09:33 PM.
08-15-2016, 04:47 PM
#20
Melting Slicks
Priya, anything to report back; what did you end up doing?
I'm now mulling over many of these same ideas with my own 79 L82.
I thought I was going to go with an off-the-shelf modern TBI EFI system like the about-to-be-released Holley Sniper EFI, BUT port EFI with a modern designed-for-air intake system and the extra fuel economy AND torque is calling my name all of a sudden...
Adam
I'm now mulling over many of these same ideas with my own 79 L82.
I thought I was going to go with an off-the-shelf modern TBI EFI system like the about-to-be-released Holley Sniper EFI, BUT port EFI with a modern designed-for-air intake system and the extra fuel economy AND torque is calling my name all of a sudden...
Adam