million dollar tpi question.
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From: manchester, NH
Car: 1998 grand cherokee, 1988 iroc z
Engine: 350 tpi
Transmission: 700r4
Axle/Gears: ???
million dollar tpi question.
I have an 85 z28 305 tpi
swapping to a 350. keeping existion tpi from 85.
I cant seem to find a prom from an 85 vette. so I went ahead and picked up an ecm and the wire harness from an 87.
the question is will the 87 harness work with my 85 tpi. with out modding it.
I really don't want to alter any thing due to lack of know how.
or if any body knows where I can get a prom which would probably be the easiest way.
swapping to a 350. keeping existion tpi from 85.
I cant seem to find a prom from an 85 vette. so I went ahead and picked up an ecm and the wire harness from an 87.
the question is will the 87 harness work with my 85 tpi. with out modding it.
I really don't want to alter any thing due to lack of know how.
or if any body knows where I can get a prom which would probably be the easiest way.
Supreme Member
Joined: Jan 2003
Posts: 2,043
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From: San Diego
Car: 1994 Trans Am
Engine: LT1
Transmission: Auto
Axle/Gears: 3.23
Re: million dollar tpi question.
If you can't find anything, the memcal and maf will work fine. I had an '85 trans am and I put a 350 block and used everything my car had and it ran great. The ecm can tolerate a 10-15% change in displacement.
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From: Waxahachie Texas
Car: 88 IROC Z/28-under re-construction
Engine: 5.7 Tuned Port
Transmission: It's in there....
Axle/Gears: 9 bolt Borg-Warner
Re: million dollar tpi question.
don't you need to go with the 22lbs injectors to get the full benefit of the 350?
305's are 19lbs
305's are 19lbs
Thread Starter
Junior Member
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Joined: Nov 2008
Posts: 63
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From: manchester, NH
Car: 1998 grand cherokee, 1988 iroc z
Engine: 350 tpi
Transmission: 700r4
Axle/Gears: ???
Re: million dollar tpi question.
it is maf, what about this burn off thing? doesn't the 85 have a separate relay or something that the latter years incorporated into the ecm?
Thread Starter
Junior Member
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Joined: Nov 2008
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From: manchester, NH
Car: 1998 grand cherokee, 1988 iroc z
Engine: 350 tpi
Transmission: 700r4
Axle/Gears: ???
Re: million dollar tpi question.
yes, i got the injectors, im just trying to get everything i need before i start ripping things apart so i wont really have to stop and forget where things go. my main concern is the engine electronics.
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Thread Starter
Junior Member
iTrader: (2)
Joined: Nov 2008
Posts: 63
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From: manchester, NH
Car: 1998 grand cherokee, 1988 iroc z
Engine: 350 tpi
Transmission: 700r4
Axle/Gears: ???
Re: million dollar tpi question.
got the knock sensor, trying to see if there are sensors and relays used in one year and not the other, stuff like that
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From: Mercedes Norte, Heredia, Costa Rica
Car: 1984 Z28 Hardtop
Engine: 383 Carb
Transmission: 4L60
Axle/Gears: 3.54 Dana 44
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From: Texas
Car: 1992 Formula Firebird
Engine: 305CID (LB9)
Transmission: World Class T5
Axle/Gears: 10-bolt, 4.10 gears
Re: million dollar tpi question.
As I understand it the computer and the wiring harness are different for a 1985 car. The actual TPI plenum and runners are pretty much the same and are compatible so you can use those along with the fuel rails. You either need to plug the 9th injector hole or leave an injector in place but disconnected. So in short the answer is yes: You can use 1986 or newer wiring harnesses and ECM with the older TPI hardware. For a 350 to work properly you will need the knock sensor for a 350 and you'll want to use 22lbs. injectors if the 350 is similar in power and configuration to the L98. (The factory 5.7L 350 TPI engine.) If you are putting in a more powerful Chevy 350CID engine, you'll probably need larger injectors and a higher pressure fuel pump. You will also need to reprogram the ECM in order to get the best performance out of your 350.
The TPI hardware is essentially the same from 1986 to 1989. It was changed from MAF to speed density in 1990 and remained virtually unchanged up until 1992.
The TPI hardware is essentially the same from 1986 to 1989. It was changed from MAF to speed density in 1990 and remained virtually unchanged up until 1992.
Last edited by 87WS6; Jan 8, 2010 at 01:09 PM.
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Joined: Oct 2009
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From: Lasalle,Ontario,Canada
Car: 1987 camaro iroc
Engine: 350
Transmission: 5 speed borg warner
Axle/Gears: 3.45
Re: million dollar tpi question.
305 TPI to 350 TPI Conversion
If you are looking to convert your car from a 305 TPI to a 350 TPI setup, then you should find the information below rather useful. These are all the needed changes to do the conversion.
First of all, the TPI intakes (manifold, plenum, fuel rails, throttle body, runners) were exactly the same between 305 and 350 engines of the same year. There were no differences in these parts whatsoever between one engine size and the other during any year (there were however differences between the intake manifold and fuel rails between the Camaros and Corvettes). For example, a 1987 intake was the same for both a 305 and 350. Please note that this does not mean all intakes are the same throughout the years, there are differences between a 1987 intake and a 1992 intake for example.
All your belt driven accessories, brackets, exhaust, etc... will transer over from the 305 to the 350 without any problems. Once you install the TPI intake on the larger engine, you will need to note the following items that need to be changed. These are the only things you will need to change or worry about to properly convert to a 350:
Injectors
The size of the injectors was a very important difference between 305 and 350 applications. ALL 305 TPI engines came from the factory with 19 lb injectors. ALL 350 TPI engines came from the factory with 22 lb injectors. The Corvettes did not have injectors any larger than the Camaro, as I have people often asking. If you want to use 19 lb injectors on a 350, or 22 lb injectors on a 305, you can, but you MUST have the injector size in the PROM changed. Otherwise, you will run into fueling problems.
Knock Sensor
The knock sensor physically looks the same between the 305 and 350 version, but they do are not the same. This is very important, and should not be overlooked. The knock sensor is responsible for detecting detonation. Detonation produces a specific frequency that travels through the engine block. This frequency is different depending on engine size. In addition, it is important to note that the 350 knock sensors were different between the 85-89 TPI setups and the 90-92 TPI setups. You must use the correct one for your application. The 305 knock sensors were also different between 85-89 and 90-92.
ESC Module
The 85-89 TPI setups used an external ESC module which was mounted by the firewall. This module was different between 305 and 350 engines. Changing this is as simple as disconnecting the 305 module, and plugging in a 350 module. The 90-92 TPI setups did not have an external ESC module. Instead, the ESC circuitry is contained inside the PROM. For this and several other reasons, it is important that you use the correct prom for the engine size you are using.
ECM
Although there were several different ECMs used depending on what year TPI setup you have, the same ECM was used for 305 and 350 engines for a given year. The difference between the engines was the prom. In other words, the 86-89 350 TPI engines used the 1227165 ECM, and so did the 86-89 305 TPI engines. The 90-92 350 TPI F-Body engines (Camaro and Firebird) used the 1227730 ECM, and so did the 90-92 305 TPI engines. The 1985 305 TPI engines used 1226870 ECM, which is the same as the 1985 350 TPI ECM (350 was only available on the Corvette in 1985).
The Corvette used the 1227727 ECM on the 90-91 350 TPI engines. Although the Corvette was never available with a 305, the 1227727 ECM can be used on a 305 if desired.
PROM
This is probably the most important change that needs to be made. Regardless of what ECM you are using, the 305 prom is setup very differently from a 350 prom. Which prom you need will depend on what ECM you use, transmission type, engine size, and a few other details. Contact us if you need help finding the correct PROM for your application.
If you have a 90-92 ECM, and you are having your PROM reprogrammed, you must start with a PROM that was originally for a 350. The 90-92 PROMs have the ESC circuitry onboard, and that cannot be changed.
The 85-89 PROMs can be changed from one engine size to another without worrying about ESC within the PROM, since the module is external on those years.
First of all, the TPI intakes (manifold, plenum, fuel rails, throttle body, runners) were exactly the same between 305 and 350 engines of the same year. There were no differences in these parts whatsoever between one engine size and the other during any year (there were however differences between the intake manifold and fuel rails between the Camaros and Corvettes). For example, a 1987 intake was the same for both a 305 and 350. Please note that this does not mean all intakes are the same throughout the years, there are differences between a 1987 intake and a 1992 intake for example.
All your belt driven accessories, brackets, exhaust, etc... will transer over from the 305 to the 350 without any problems. Once you install the TPI intake on the larger engine, you will need to note the following items that need to be changed. These are the only things you will need to change or worry about to properly convert to a 350:
Injectors
The size of the injectors was a very important difference between 305 and 350 applications. ALL 305 TPI engines came from the factory with 19 lb injectors. ALL 350 TPI engines came from the factory with 22 lb injectors. The Corvettes did not have injectors any larger than the Camaro, as I have people often asking. If you want to use 19 lb injectors on a 350, or 22 lb injectors on a 305, you can, but you MUST have the injector size in the PROM changed. Otherwise, you will run into fueling problems.
Knock Sensor
The knock sensor physically looks the same between the 305 and 350 version, but they do are not the same. This is very important, and should not be overlooked. The knock sensor is responsible for detecting detonation. Detonation produces a specific frequency that travels through the engine block. This frequency is different depending on engine size. In addition, it is important to note that the 350 knock sensors were different between the 85-89 TPI setups and the 90-92 TPI setups. You must use the correct one for your application. The 305 knock sensors were also different between 85-89 and 90-92.
ESC Module
The 85-89 TPI setups used an external ESC module which was mounted by the firewall. This module was different between 305 and 350 engines. Changing this is as simple as disconnecting the 305 module, and plugging in a 350 module. The 90-92 TPI setups did not have an external ESC module. Instead, the ESC circuitry is contained inside the PROM. For this and several other reasons, it is important that you use the correct prom for the engine size you are using.
ECM
Although there were several different ECMs used depending on what year TPI setup you have, the same ECM was used for 305 and 350 engines for a given year. The difference between the engines was the prom. In other words, the 86-89 350 TPI engines used the 1227165 ECM, and so did the 86-89 305 TPI engines. The 90-92 350 TPI F-Body engines (Camaro and Firebird) used the 1227730 ECM, and so did the 90-92 305 TPI engines. The 1985 305 TPI engines used 1226870 ECM, which is the same as the 1985 350 TPI ECM (350 was only available on the Corvette in 1985).
The Corvette used the 1227727 ECM on the 90-91 350 TPI engines. Although the Corvette was never available with a 305, the 1227727 ECM can be used on a 305 if desired.
PROM
This is probably the most important change that needs to be made. Regardless of what ECM you are using, the 305 prom is setup very differently from a 350 prom. Which prom you need will depend on what ECM you use, transmission type, engine size, and a few other details. Contact us if you need help finding the correct PROM for your application.
If you have a 90-92 ECM, and you are having your PROM reprogrammed, you must start with a PROM that was originally for a 350. The 90-92 PROMs have the ESC circuitry onboard, and that cannot be changed.
The 85-89 PROMs can be changed from one engine size to another without worrying about ESC within the PROM, since the module is external on those years.
Thread Starter
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Joined: Nov 2008
Posts: 63
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From: manchester, NH
Car: 1998 grand cherokee, 1988 iroc z
Engine: 350 tpi
Transmission: 700r4
Axle/Gears: ???
Re: million dollar tpi question.
ok, so i should be good as long as I change the injectors, knock sensor, and the esc module.
the 85 ecm with matching wire harness will work on the 85 TPI should be plug and play.
wish me luck. I'll be back with question as they come. thanks folks.
as for a cam, any ideas?
I got a set vortec fast burn heads and going for the intake that will fit. heads are untouched. I'll more than likely up grade the springs.
and not looking to reprogram any thing unless i have to. (as of right now)
the 85 ecm with matching wire harness will work on the 85 TPI should be plug and play.
wish me luck. I'll be back with question as they come. thanks folks.
as for a cam, any ideas?
I got a set vortec fast burn heads and going for the intake that will fit. heads are untouched. I'll more than likely up grade the springs.
and not looking to reprogram any thing unless i have to. (as of right now)
Last edited by mattyc; Jan 9, 2010 at 06:16 AM.
Joined: Jul 2003
Posts: 10,532
Likes: 204
From: NYC / Jersey
Car: 1990 Trans Am GTA
Engine: Turbo 305 w/MS2
Transmission: 700R4
Re: million dollar tpi question.
Originally Posted by mattyc
I have an 85 z28 305 tpi, swapping to a 350. keeping existion tpi from 85....
Junior Member
Joined: Sep 2008
Posts: 59
Likes: 0
From: New York
Car: 1988 Camaro IROCZ
Engine: 305 TPI
Transmission: T5
Axle/Gears: Stock
Re: million dollar tpi question.
i have a 1987 IROCZ, during the summer i did a 305 to 350 TPI swap. i got a 350 prom chip from TPI parts. u can keep ur stock ecm, and all u have to do is unplug ur 305 chip, take the blue (or whatever color it is for u) cover and plug the 350 chip to the 305 chip, then install. U just would have to play around with it to get it perfect but it works great for me. U tell TPI parts everything u have, u tell then the vehicle year, make/model, trans type and ur desired changes and they burn it for u.
Website below:
http://tpiparts.net/inc/sdetail/1495
hope this helps u out, and good luck
Website below:
http://tpiparts.net/inc/sdetail/1495
hope this helps u out, and good luck
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Joined: Jun 2008
Posts: 1,298
Likes: 2
From: Norfolk VA
Car: 85 Camaro IROC
Engine: 5.7 TPI
Transmission: 700-R4
Axle/Gears: open rear, 3.42 gears
Re: million dollar tpi question.
the problem is that for owners of 85 TPI cars, there is no other chip to use.
85 was a one year only computer, and there were other differences as well.
the best thing to do for an 85 is to upgrade to a later computer, or just have the chip burned for you.
if you have the chip burned, you will not be happy because it will probably not be very good.
since apparently you can use the stock 305 chip and it will compensate, i would do that.
then put in 22 lb injectors and see what needs doing next.
this wont work on a high HP build, but for a "mostly stock" engine it will work.
85 was a one year only computer, and there were other differences as well.
the best thing to do for an 85 is to upgrade to a later computer, or just have the chip burned for you.
if you have the chip burned, you will not be happy because it will probably not be very good.
since apparently you can use the stock 305 chip and it will compensate, i would do that.
then put in 22 lb injectors and see what needs doing next.
this wont work on a high HP build, but for a "mostly stock" engine it will work.
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