I have a 91 RS with a crate 350 TBI. I would like to convert it over to a TPI. My question is....What all will I have to change to make it work, would I be able to do it myself or woult it need to be done by someone professionaly, and how much would it cost? If anyone has any idea, let me know.

 

Its not that hard, just time consuming. Probably the most difficult part for me was the wiring harness. I had my harness converted to TPI from TPIparts.net. You will need the whole intake system (upper, lower, Throttle Body, Plenum, Runners, EGR(if used), Fuel Rail, TPI fuel pump, All the sensors, (about 7-8 sensors), Tpi ECM, TPI memcal for a 350, Harness, New Injectors, Gaskets, New Throttle Cable, New Kickdown cable, adjustment of Cruise cable. All sorts of goodies.....it does add up fast though, believe me.

I did the same swap except I started with a 305 TBI and swapped for a modified 350 TPI. Its a long road unless you've got unlimited time to play.

 

That sounds fun. I know I could find a TPI system for cheap but I have no clue about all the sensors and all. I guess I will start looking, thanks for all the help man.

 

There is also a book called TPI Swappers Guide, look for it, I promise it will clear up some of the questions you might have.

 

Check this site out too! Lots of good info and very helpful when I did my swap.

Chevythunder

 

Thanks a lot guys. Also, do you think I should go for the swap, or just go for a new Z with it all done already? The only thing is, I have a new crate in there, so I kinda wanna jsut swap.

 

Do the swap, cheaper in the long run. You can leave the old engine in and just swap out the intake system. Its not that hard. Just be sure to get a GOOD harness. You do not want to replace the harness after you've done the swap due to faulty wiring!

 

Yeah, be sure to buy a good harness or make your own; it's mostly time consuming if you're patient, a lot of the wires should be the same if you go with a late model speed density setup; If you do it solder/heat shrink your connections it will be as functional as a pre-made harness and cost a ton less.
Just add wires in for what you need to add (more injector lines etc.) You'd want to use a chip that would disable the VATS system, not a big deal since I'd want a performance chip or custom tune anyways.
I've rolled a harness to do a TBI->GN motor swap in a minivan, I just took the books for both model year vehicles and made a list of every pin in the connector. After this, I wrote the function of each pin down on the van/GN harness. around 2/3rds of the electrical was the same (grounds, IAC etc.) or I could just move pins around in the connector. To do this you pull the little clips that are electrical taped to the harness bundle and then just pull on the wires and re-insert them where necessecary. Other then that a lot of time was spent extending lines for stuff like the IAC, TPS etc. I was using two motors to mock it up and extend the wiring as necessecary, but if you did it in-car it'd probably be easier. I probably had 24 man hours into that harness from planning to soldering/heat shrinking it but keep in mind that my intentions were to go from a speed density TBI setup with a distributor to a MAF setup that was distributorless. your changes should be WAY easier to complete. I had about $30-40 into my harness. It's more then a few hours but with the cost of a Painless harness it makes a lot of fiscal sense to me.

 

Not trying to bash, but why not just go carbureted? Cheaper, more potential upper-end power, and you can still get decent mileage with a properly sized and tuned carb.

Again, not trying to bash, just saying.

 

I thought about a carb also before my swap, but I thought all hot rodder all want carbs. TPI is a little different, and most people think they're inferior, but actually make a crap load of torque. I'm glad I went fuel injected, says something you know? Although, on the other hand the next project car I buy will be a carbed engine. Definatly easier.

 

The reason I actually have to say away from carb is because of emissions. I have to stay emission legal to keep it on the road, otherwise, I probably would go carb, TPI just makes more sense to me though.

 

You know alot of people say TBI is inferior.....I dunno what their talking about

Do a search for TBI to TPI swap under Fast355's name, he did a rather informative swap and came up with less HP than TBI but a boat load more torque between 2500 and 3500 rpm. I'm not trying to stir anything up, just making sure you have all the facts so you can decide if TPI is right for you. If you haven't done it already, you need to get a 350 chip, knock sensor and injectors for your TBI setup. You could have 30-50 hp locked up in it right there depending on how far off the tune is.

 

Where can I get those?

 

You might want to stop over at the TBI board and check out the stickies. There's a sticky at the top of the page that covers everything you need to know about 305 to 350 swaps.

You can get everything at your local parts store, junk yard or ebay.

 

Alright, thanks man.

I have also been looking into another system. I am sure you have all heard of them, but not many run it. It will cost me a little more then a TPI but it is the system made to bolt on the TBI, the Multi-port EFI System I believe. I might go that route too, what would you all think? It runs between 1 and 2 grand with all wires, computers and all.

 

TBI might be alright for those guys ...but trust me...you don't want anything to do with it unless you are as sharp about that stuff as they are.