lostpatrolman

I want to get away from my carb and put fuel injection on my car. Im too cheap to buy ready to run kits for over 2k. Someone sent me a link to an LT1 converion, the page was focused toward a tpi to LT1 conversion and was vague about what is needed to run on a carb setup. What would i need? I assume i would need to either get a wiring harness from painless wiring or make my own. Could I used the ECM from the fbody, or would i need a standalone.. if so what is a good ECM. What kind of distributor would work, would an electronic distributor with a tach drive be ok? Is there anyway to wire up a knock sensor that would retard timing if it hears detonation? Thank you for your help.


[Modified by lostpatrolman, 7:01 AM 3/11/2004]

Armstrong

I'm interested to hear replies on this one so i'll TTT

Fevre

Basically if you bought a used TPI system (about $400 ) and then add the LT1 intake (another $400) plus odds and ends ($300) you would be good to go. Try picking up a couple books on TPI, I have 'TPI Swappers Guide' and 'How to Tune and Modify Chev TPI Engines'. Main reason people switch from the stock TPI intake to the LT1 is it allows more air flow thus high rpm's making more power, so you might be good to just run the stock TPI intake if it fits your needs. The books are great info and will aid you in your decision as to whether a swap is right for your needs.

markdtn

This is written for TPI.

You have a unit
First you have to determine whether you want mass air flow or speed density. The C3 is more conducive to speed-density due to space issues. Mass-air flow is easier to make engine changes without PROM changes. If you are technically proficient enough to make a Camaro harness work they can be bought for $100 or less. Aftermarket harnesses range from about $300 for Painless to $500 for Howell to $700 for Street and Performance. Howell makes a great harness, but for a Tuned Port they do not make one that will control the converter lockup on a 200R4/700R4/4L60 transmission. If you are running a manual trans or non-overdrive I would highly recommend them. I have heard great things about Street and Performance harness, but do not have first hand experience with them. I also have a Fuel Injection Specialties (FIS) harness and it is OK. The ECM can be had used for $10-50. A good external fuel pump will cost at least $100. I use an 88 Ford Truck external pump, $114 from CarQuest, made in Texas by Airtex. If you have a 78-82 you can use your fuel tank with an 82 sending unit and a TPI pump. An aftermarket PROM with VATS and Emissions codes removed will be $100-200 depending on source and complexity. You will have to add an oxygen sensor to your exhaust, $20 for the sensor, $5 for the weld-in bung, and say $25 for an exhaust shop to weld it in if you can’t. Some harnesses use VSS and some do not. An auxiliary VSS sensor is around $75. To install a TPI I say figure at least $800 plus the TPI unit and whatever repairs are necessary to bring it up to useable status. I have TPI/700R4 in my 69 Corvette (Howell harness) and an 83 Pickup (FIS harness) and I love it. Starts good, great torque, good fuel mileage, easy to swap onto stock engines (although both of mine are out of 90/91 ‘Vettes).

Differences in years
All Corvette TPI intake manifolds work with the older (through 86) iron heads and the factory aluminum heads through 91. F-body TPI intakes use the upright center bolts on 87-92 and thus fit all 87-95 iron heads (non LT1). Either can be swapped to fit the other with some drilling. F-body has the fuel lines come out on the drivers side and has a central port for EGR. Corvette has fuel lines that come out on the passenger side and has an external port for EGR. The runners are all the same through the years, but the LH runner has a hole for a 9th injector in the 85-88 runners. This can be plugged off if you get a nice LH runner and don’t want the 9th injector or decide to run speed-density. The plenums all physically interchange, but 90-92 have an extra vacuum port for the MAP sensor used with the speed-density computers and wiring. 89 is an odd year, it is mass-air flow but without the 9th injector. 89 up throttle bodies can be used on all years, but a 85-88 throttle body requires a ½” hole be drilled in the front of a 89-92 Plenum for idle air. 89-92 Throttle bodies have a bit more desirable cable attachment. The cable attaches around a circular linkage which has a smoother actuation than the straight linkage on the 85-88. The Corvettes have an aluminum plenum extension over the distributor, the F-body extensions are plastic. The Corvettes use an HEI coil-in-cap distributor for 85-91 (Delco 1103680). 85-86 F-body also used a big-cap distributor. 87-92 F-Body used a small cap distributor with an external coil (Delco 1103479). This same distributor is used in the 87-95 5.0/5.7/7.4 TBI injected trucks.

Why to get it
If all you want is around 300 hp there is no reason to spend a pile of money on a crate motor. The basic $1200 4-bolt Goodwrench 350 with an aluminum intake and a Holley will put out power in that neighborhood. Chevy High Performance (I think) did a series of articles with one of those a few years back and with decent exhaust should get you in that range.

I would look into a TPI. They start immediately in winter, have great vacuum, and will get great mileage. I can open the headlights and the wiper door at the same time with no hesitation at all-solid wooomp. With 3.70 gears (and a 700R4 overdrive) I get 18mpg city and 22+ highway. With 3.55 or 3.36 it would be even better. You can probably find a used Corvette TPI engine for $1000 and with an $800 harness/computer/fuel pump you would be set. On a 78-82 you can use the stock fuel tank with an 82 sending unit and TPI pump and be in better shape than 68-77 with an external pump. With the Vette TPI you would have aluminum heads that would remove weight. Even with an F-body iron-head TPI 350 it will be less weight than a stock intake. It will bolt up to everything in your car, use stock accessories, use your transmission, and the visual appeal is awesome. Don't be afraid of fuel injection, it really works.

As far as websites see: http://www.corvettefaq.com for conversions or more TPI info at http://www.fuelinjection.com

lostpatrolman

Thank you for the info, but why would i need to convert to tpi first? Couldnt i just strip the intake, injectors, fuel rail, ecm, speed density, throttle body nd the rest of the goodies off of a LT1, and not need any TPI stuff at all? As for the wiring, could i cut off the factory ends and make my own harness, seems alot cheaper.

lostpatrolman

There are currently 2 LT1 intakes on ebay that i am looking at... does it look like i need much more then what these have? I know i will still need a ecm, remote thermostate, and wiring. Is there anything else that is missing? http://cgi.ebay.com/ebaymotors/ws/eB...EBWA%3AIT&rd=1
http://cgi.ebay.com/ebaymotors/ws/eB...EBWA%3AIT&rd=1


Is anyone using the megasquirt ecm? http://www.bgsoflex.com/megasquirt.html or should i stick with a factory fbody ecm and get the chip flashed?


[Modified by lostpatrolman, 5:12 AM 3/12/2004]

Fevre

As long as you can make the necessary modifiactions yourself they look good for the price. Try over at www.thirdgen.org a lot of very inventive guys over there who have converted to FI from carbs and TBI's.

mrvette

The LT1 intakes do not have the distributor mounting holes, as they used the Opti-crap system, known for failure due to moisture....and funky wiring...

they can be machined to take one though....but it has to be done very carefully, obviously.....

the rest of the changes are simple by comparison....

any TPI base can be altered by siameseing the adjacent runners on the input side of the base, after the tubes.....this effectively makes a LT1 style induction, costing slight torque losses, but gaining upper HP and useable rpms/

I think junkyard ECM connectors fromt he same car you pull a MAP computer from will do the job just fine, get all the wiring you can....GM# 1227730 is about the best for the job at ten bux each....get all the sensors you can from any easy to reach suitable engine, MAP, water temp, air temp, connectors, everything....O2 sensors also...maybe even cut the exhaust pipe for the O2 bung, to be super cheap....with headers you will need a heated O2 sensor, look around in the chrysler junk pile....pull one of those, works fine...

you will need a DVM and know how to use it....

you will need soldering ability....and shrink wrap/good taping/harnessing ability....run the harness throug a hole drilled in the 'crotch' of the a/c ducting which comes out to the lower pass side of the dist......you will see what I"m talking about when you pull the dash apart...

the 1227730 controlls the tranny allready, so no sweat there....

the only expensive part is the 80 bux for the speedo sensor conversion piece...that makes the VSS adapted in with the old mechanical speedo....

GENE

markdtn

I read your post again and I guess I don't understand what you want to do. If you want a cheap throttle-body type setup you can buy stock 87-96 truck stuff cheap. You could probably get 82/84 Cross-Fire dual throttle body stuff fairly cheap too and use all factory stuff that will bolt to your engine (might have to modify some bolt holes on the 87-96 TBI manifold). With a regular TPI you could make a harness from factory parts and use O2, MAP, Coolant temp sensors from various GM cars, the 7730 ECMs are cheap but you still need a custom PROM to get rid of nusience codes (A/C, EGR, canister purge, etc.) and to disable VATS. It won't start unless VATS is removed. You could go mass-air flow and use the other ECM w/o VATS, but you have to loacte a MAF sensor then. I'll have to read up on the LT1 intake conversion, I don't know about it.

Fevre

If you are going to run a cam with less than 215 duration at .050 lift then ported base TPI MAF system will work great for you, once you get above that then you really need more airflow so you would switch intakes to the LT1 or other aftermarket intakes and maybe Speed Density but their is a debate as which is better so you'll need to research it and decide for yourself which suites your needs. Some people really like the LTR (Long Tube Runner) set ups since they offer awesome off the line torq, others like to rev their engs high so the LTR intakes don't work so well. Unless you are very familiar with electronics and FI system I would not try to peice together system for your first one. If you are handy and good with apply book knowledge then give it a go.

Best of luck no matter what yo choose and keep us updated on your progress.

:thumbs:

lostpatrolman

Thanks for your input guys. If i can get a mostly complete setup from ebay, then i will attempt the conversion. Markdtn, my goal is to put together a decent fuel injected setup that likes to rev on my vette for as cheap as possible. I am hoping to get better gas mileage also. The LT1 intake seems like it is the system i want. A little bit of a challenge always makes things more interesting!

markdtn

If you want to rev, you don't want stock TPI. On the good side, with stock TPI you can't hardly get enough air into the engine to over-rev it.