Hey all, I have a 1991 Camaro Z28 with the F code 305 tpi engine. A friend of mine has a 350 Tpi engine. I think im going to buy the engine from him and swap it for my 305. What do I need to do this? Can my ECM be reprogrammed for the 350? can my ecm run the 350 even very poorly i its calibrated as a 305? Also is the harness the same? A list of what i would need or answers to these questions would be great!
Thanks
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Member
http://tpiparts.net/305_tpi_to_350_tpi_conversion
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.
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.
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.
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).
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.
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.
Junior Member
I have a 1989 Iroc with 305 TPI. I want to go to a 350 TPI and keep it simple. Can someone recommend what kind of 350 crate engine would work best to get me up to about 325-350 ft-lbs of torque and not much more beyond that (so I don't blow up the tranny)
I DO NOT want to replace my T-5 tranny, stock exhaust manifold, and stock TPI plenum-runners-intake. I want to keep all the sensors the same if possible with the exception of the knock sensor and ESC. Would only like to go to the 350 with the 22lb injectors and get my PROM changed/reprogrammed. Would a chevy 350/290 crate engine work with my stock intake?
What would be a good horsepower target and recommended 350 crate engine?
Can I get an engine setup (e.g. different cam), that will provide more HP at the higher RPM range (highway)? Any recommendations there?
Alternatively, is getting a 305 crate engine that is more powerful an option and simpler/cheaper/smarter in my case and I can keep the injectors and PROM as is? Bottom line: Going beyond 325 ft-lbs torque means upgrading a lot of other stuff which is $$$ and time.
Thanks ! :-) --Alex
I DO NOT want to replace my T-5 tranny, stock exhaust manifold, and stock TPI plenum-runners-intake. I want to keep all the sensors the same if possible with the exception of the knock sensor and ESC. Would only like to go to the 350 with the 22lb injectors and get my PROM changed/reprogrammed. Would a chevy 350/290 crate engine work with my stock intake?
What would be a good horsepower target and recommended 350 crate engine?
Can I get an engine setup (e.g. different cam), that will provide more HP at the higher RPM range (highway)? Any recommendations there?
Alternatively, is getting a 305 crate engine that is more powerful an option and simpler/cheaper/smarter in my case and I can keep the injectors and PROM as is? Bottom line: Going beyond 325 ft-lbs torque means upgrading a lot of other stuff which is $$$ and time.
Thanks ! :-) --Alex
Supreme Member
Quote:
Thanks
Not to rain on your parade but I think its foolish and a waste of time and effort to swap a 305TPI (F code) for a 350TPI (8 code). There is a 20hp difference between the two and I highly doubt you will ever feel the difference. You will get a better seat of the pants feeling by just swapping out the rear gears. I have had both a 91Z28 with the 305TPI and the 350TPI and both cars ran within 1/10th of a second of each other at the track. Both were stock.Originally Posted by camaroman9191
Hey all, I have a 1991 Camaro Z28 with the F code 305 tpi engine. A friend of mine has a 350 Tpi engine. I think im going to buy the engine from him and swap it for my 305. What do I need to do this? Can my ECM be reprogrammed for the 350? can my ecm run the 350 even very poorly i its calibrated as a 305? Also is the harness the same? A list of what i would need or answers to these questions would be great!Thanks
Junior Member
I have the same issue and want to know is there a 350 engine that will give me maybe 50+ more horsepower without replacing anything stock on the car (with the exception of injectors, knock, PROM, and ESC).
My '89 305 TPI has over 330K on it - Not sure how long it will last - anyone have a guess as to what the record is for such an engine? - but I drive it every other day. The only jobs performed were a new distributor, MAF, and new 19lb injectors 2 yrs ago which really gave it back a lot of lost power.
So when that day comes - what is the recommendation? 305 or 350? I'm shooting for 325 ft-lbs of torque and maybe anywhere from 250-275 HP. Any particular 350 crate engine someone can recommend?
My '89 305 TPI has over 330K on it - Not sure how long it will last - anyone have a guess as to what the record is for such an engine? - but I drive it every other day. The only jobs performed were a new distributor, MAF, and new 19lb injectors 2 yrs ago which really gave it back a lot of lost power.
So when that day comes - what is the recommendation? 305 or 350? I'm shooting for 325 ft-lbs of torque and maybe anywhere from 250-275 HP. Any particular 350 crate engine someone can recommend?
Junior Member
Quote:
My '89 305 TPI has over 330K on it - Not sure how long it will last - anyone have a guess as to what the record is for such an engine? - but I drive it every other day. The only jobs performed were a new distributor, MAF, and new 19lb injectors 2 yrs ago which really gave it back a lot of lost power.
So when that day comes - what is the recommendation? 305 or 350? I'm shooting for 325 ft-lbs of torque and maybe anywhere from 250-275 HP. Any particular 350 crate engine someone can recommend?
Please correct me if I'm wrong but, from the factory your IROC made right around 200 HP for the automatic and 220 for the 5 speed and 295 ib-ft of torque. The TPI 350s got right at 230 hp and 330 lb-ft of torque. With a stock 350 that's going to put you a lot closer to your goal already. Now the question is how do you want to spend your money? You could find a used 350 block and rebuild it, or get a short block from GM performance. Then you can do a port job on your 305 heads and put those on it maybe add a slightly bigger cam, and you would be hitting pretty close to your mark. I'm not sure how much you would save if you were to do a rebuild vs a crate engine. In my experience a GM performance long block crate engine was $2200, I bought a complete parts car for $1000 and took the engine out of it and for $1200 I got a rebuild kit with forged dome top pistons to get 10:1 compression, bigger valves, comp Xtream energy came and lifter kit+valve springs, and all the machine work. Granted I did spend the same amount but I was able to get more out of the money I had. I'm not saying that's what you should do by any means, I'm just telling you what I've learned.Originally Posted by alexiroc
I have the same issue and want to know is there a 350 engine that will give me maybe 50+ more horsepower without replacing anything stock on the car (with the exception of injectors, knock, PROM, and ESC). My '89 305 TPI has over 330K on it - Not sure how long it will last - anyone have a guess as to what the record is for such an engine? - but I drive it every other day. The only jobs performed were a new distributor, MAF, and new 19lb injectors 2 yrs ago which really gave it back a lot of lost power.
So when that day comes - what is the recommendation? 305 or 350? I'm shooting for 325 ft-lbs of torque and maybe anywhere from 250-275 HP. Any particular 350 crate engine someone can recommend?
Junior Member
Hi, Your torque and hp numbers are exactly correct, I have the 5-spd T5. What you did sounds very interesting. Did you use 22lb injectors and had the PROM reprogrammed for the larger injectors? Are you still using the stock manifold?
Main Question - how does it all run? I was told by some folks that sell engines that the '89 computer "will not work right" with 350's with more aggressive cams. They said "the computer was not designed for more powerful 350 engines so you may have idling problems, etc". Did you need to replace your computer or do anything special?
I already ruled out the 350/290 swap cause the intake will not bolt on. So to keep it simple am looking to get a remanufactured 350 engine - like an L98. What I don't know is, should I go for a stock/mild cam or something more bigger? I will also want to get a long block, don't really have the time to rebuild it like you did, I just want to plop it in with all of the existing hardware, and get 50 more horses, and want it pass emissions. Only thing to change: Injectors, Prom, ESC, and Knock.
So am really interested in how it worked out for you. Tell me more about about your car - year/tranny/type of cam, what you did going from 305 to 350.
Thanks!!
--Alex (still going strong with 330K on my '89 z28 , LB9, T5)
Main Question - how does it all run? I was told by some folks that sell engines that the '89 computer "will not work right" with 350's with more aggressive cams. They said "the computer was not designed for more powerful 350 engines so you may have idling problems, etc". Did you need to replace your computer or do anything special?
I already ruled out the 350/290 swap cause the intake will not bolt on. So to keep it simple am looking to get a remanufactured 350 engine - like an L98. What I don't know is, should I go for a stock/mild cam or something more bigger? I will also want to get a long block, don't really have the time to rebuild it like you did, I just want to plop it in with all of the existing hardware, and get 50 more horses, and want it pass emissions. Only thing to change: Injectors, Prom, ESC, and Knock.
So am really interested in how it worked out for you. Tell me more about about your car - year/tranny/type of cam, what you did going from 305 to 350.
Thanks!!
--Alex (still going strong with 330K on my '89 z28 , LB9, T5)
Junior Member
Basically I'm using everything that came on a stock IROC with a TPI 350. Only difference is, I had to have the prom reprogrammed for the aftermarket harness I had made and to cope with the cam I added. Plus I had the EGR and air injection deleted from the programming.
Unfortunately I don't have the engine assembled. I've been getting stuff taken care of at the machine shop. As far as your cam goes this is the cam I got http://www.summitracing.com/parts/cca-cl08-502-8 and here's the matching valve springs http://www.summitracing.com/parts/cca-986-16 . My machine shop guy who happens to be my girlfriends dad, said this would be a good cam option and the guys at Tempe Speed and Performance (company that made my harness) agreed plus I talked to the guys at comp too. I completely understand about the crate engine that'll definitely help out on time, now I have a recommendation. If you want, see if you can get an L98 from a Corvette of the same year model, that'll get you aluminum heads and more horses but id research that option to see if its feasible and worth it. But, if you wanna make power put your money in heads, that's coming from my boss who is a master tech and should've been an engineer, he's a very smart man. As far as my car goes its a 91 RS that had a 305 TBI, I'm using the tranny that came out of the 91 which would be your standard 700R4, and as of now my progress is I have the 305 pulled out, I plan on using the serp belt system from the 305, I have already purchased the MAS air wiring harness and had the PROM programmed to run the powertrain, the engine upgrades are: Bored 0.030 over, 0.00100 over valves, forged dome top pistons, arp rod bolts, comp cams extreme energy cam and lifter kit+springs, screw in studs to put up with the higher tension springs, and full roller rockers. Hopefully I was able to answer most of what you asked but that's what I've got.
Unfortunately I don't have the engine assembled. I've been getting stuff taken care of at the machine shop. As far as your cam goes this is the cam I got http://www.summitracing.com/parts/cca-cl08-502-8 and here's the matching valve springs http://www.summitracing.com/parts/cca-986-16 . My machine shop guy who happens to be my girlfriends dad, said this would be a good cam option and the guys at Tempe Speed and Performance (company that made my harness) agreed plus I talked to the guys at comp too. I completely understand about the crate engine that'll definitely help out on time, now I have a recommendation. If you want, see if you can get an L98 from a Corvette of the same year model, that'll get you aluminum heads and more horses but id research that option to see if its feasible and worth it. But, if you wanna make power put your money in heads, that's coming from my boss who is a master tech and should've been an engineer, he's a very smart man. As far as my car goes its a 91 RS that had a 305 TBI, I'm using the tranny that came out of the 91 which would be your standard 700R4, and as of now my progress is I have the 305 pulled out, I plan on using the serp belt system from the 305, I have already purchased the MAS air wiring harness and had the PROM programmed to run the powertrain, the engine upgrades are: Bored 0.030 over, 0.00100 over valves, forged dome top pistons, arp rod bolts, comp cams extreme energy cam and lifter kit+springs, screw in studs to put up with the higher tension springs, and full roller rockers. Hopefully I was able to answer most of what you asked but that's what I've got.