TPI Smart Guys-

I'm thinking about doing a conversion to TPI, and I was wondering if I need the TPI specific distributor. I've got an MSD tach drive billet distributor and 6AL box right now, and I'd prefer to keep the ignition sysem I've got, so long as it will work with the TPI ECM. Any thoughts?

I am planning on using a programmable ECM, so I'll start asking questions about baseline parameters for the map once I get a little closer to bolting stuff together and hooking it up.

Thanks.

 

i think you can,,,, check with MSD

 

I don't see why you can't use your existing dist. I am assuming that it is a mechanical dist. and that the ecm would not control timing???? Are you going with a SD or a MAF TPI setup?

 

After thinking about it some more, you may still be able to use your dist. but you will need some kind of input to the ecm. I think it uses the timing pulses for firing the injectors. You might post this in the tuning section for C4's. There are some sharp SOB's over there.. Good luck!!!!

 

Conversion from what? Is this for the '74 L82 in your sig? Are you thinking of a stock TPI? What are you planning to use for a controller?

RACE ON!!!

 

Please enlighten me...
Why would anyone convert to TPI ?
.
Most conversions are from TPI to carb.

 

comp- just sent MSD Tech support an email. I'll be interested to hear what other MSD products I'll need to buy to make it work. Always wanting to sell you something you "need."

ANTIVENOM- The MSD pro-billet dist has a magnetic pickup and it's designed for use with an MSD box (not "ready to run"), so I am wondering if the electronic signal is in a different form (ie digital vs. analog). As for SD or MAF, I plan on SD, unless it gets to the too hard or too expensive stage. Thanks for the tip about the C-4 tech guys, I'll try 'em.

CFI-EFI- Yep. for the '74. I've already had a fair amount of fun swapping cams, intakes, carbs, and heads, and I figured it was time to venture into the injection world-- I guess that would be my "because I want to" response From what I understand, I'll be happier from a daily driver standpoint with injection, and TPI units are pretty readily available and there are plenty of upgrade go-fast components if I really wanted to keep playing with it. As for ECM, I will get some sort of programmable one, although my research to date on what kind is pretty meager. I understand that GM units are programmable, but I'll go aftermarket if I need to. Suggestions are welcome!

Silver-84- Quadrajet to TPI seemed to have some pretty obvious benefots. Than again, I've been wrong about my car a lot, so if I'm missing something, let me know. I love my carb, and the Q-jet is a heck of a lot better than most people give it credit for, but I like all I've read about TPI fuel economy, performance, and driveability.

Thanks.

 

I second to vote to go to electronic fuel injection, but I have to recommend against a TPI. They have only a marginal advantage over a Crossfire, and you know what everyone says about them. All the meaningful upgrades to the TPI, involve expensive manifold changes. By the time you buy a different base, runners, and plenum, you've spent $1000.00 to $2000.00, more, to improve your base purchase. Now if you start out with a SuperRam, MiniRam, or something similar, you've got something. The stand alone conversions by Holley and Edelbrock are worth consideration, also. A stock TPI will give you the advantages of EFI, but nowhere near the performance potential I think you're looking for.

RACE ON!!!

 

I agree with CFI 100% on the performance side. If you are not getting a computer and a TPI and the whole enchilada from a donor car, I would not waist time with a TPI if performance is top on your list. Good luck.

 

Thanks guys. I'm glad I asked. I wasn't aware of the limitations and problems with TPI. As I said, I was hoping to improve driveability and maybe mileage, but I don't want to do it at the expense of performance, particularly not if the TPI is as unreliable as the crossfire system.

I'll have to keep looking and do some more research. The mini ram and pro-ram are more expensive than I want. I do have a line on a complete TPI system from a donor car, so I may be able to do it on the cheap, but the loss of performance makes me not want to spend the money on the fuel delivery upgrade.

 

There is nothing wrong with the reliability of either the TPI or the Crossfire. I have had my Crossfire for 18 years and all I've replaced in that time, are fuel pumps and fuel filters. It is absolutely reliable. Unlike the TPI, the Crossfire manifold can be ported for fantastic gains in power. Improvements CAN be made porting the TPI manifold, but nowhere near as dramatic as the Crossfire. I have reduced my 1/4 mile times by OVER 2 seconds, and it has never had a head off. At 160,000 miles, the long block is untouched. I am NOT recommending a Crossfire, but the point is, without support parts available, one can WORK with a Crossfire. With a TPI, you are pretty much stuck with expensive aftermarket parts to gain much. With a good 4 bbl set up on your '74, it is possible you could actually LOSE performance with the TPI. The starting, driveablity, and fuel mileage would all improve with the TPI.

RACE ON!!!

 

Re the original Q, there is a fair amount of HEI distrib info on this board already - for example:

http://forums.corvetteforum.com/showthread.php?t=875576

http://forums.corvetteforum.com/showthread.php?t=897606



As to the merits of MPFI conversion, TPI is a 20-year old design. If its characteristics don't meet
your interests, there is a newer version that can be built using stock GM parts, ECM, & wiring:

http://www.lt1intake.com/

The difference between the long- and short-runner intakes is pretty well documented, one example
is shown here - the difference in torque curves is typical for the two designs:

http://www.lt1intake.com/dyno.htm

or here:

http://www.stealthram.com/dyno/superramvslt1intake.jpg


I haven't done the LT1 conversion myself, but if smog laws were not an issue that is the intake I
would try next. It's fairly free-breathing, and can be done using off-the-shelf materials. Plus,
it is a relatively clean looking project when you are done...

If the C4 had a little more hood clearance, the Holley SR manifold also looks interesting - there is a
general cost comparo posted here (ex injectors & electronics):

http://www.stealthram.com/intakecompare.html

There are lots of choices, depending on what sort of engine you want to end up with, and the level
of your fabricating skill.

 

Eventually ill be swapping to a ls-1 but for now i enjoy my tpi in my 73.

 

TPI is generally reliable, but you're probably ahead of the game staying w/your quad, as far as performance potential and overall cost. Changing intake gaskets on yours is a walk in the park, compared to a TPI for example. Plenty of extra stuff to remove. To each his own, though and good luck on whatever you decide.

 

thebruce,
The only thing good about (GM original) TPI is
strong mid RPM torque. The air passages... toooo
small in diameter. Aftermarket, only slightly better.
I think of TPI as, a multipoint F.I. system that was
done with the intention of not taking full advantage
of a 350 CID motor.
There are other multipoint FI systems you should think about, that don't have undersized air passages.
(L82 is bbc or sbc?)
.
Since you have a carb, you already have 'important piece'
of what other people want, a 1960s muscle car*.
I suggest that you put in a cam, and an intake manifold, to match
your driving style. (is this car a 'family driver'?)
If-when your engine starts to breathe better,
you may need to tune your q-jet.
The advantage of carb is: use any intake manifold you want. If you go to tpi, you are limited to a few
crappy choices. Go over to thirdgen, look at how many
people want to ditch GM's tpi or tbi, for carb

(* involves other stuff, lets limit the discussion to intakes)

.