questions for converting to TPI

[jbristo67]

You will need over a 100 PSI inline pump. They are pretty pricey.

[71swb4x4]

I am almost positive that 90 PSI is what the TPI runs at.

I bought a tank with an inline pump from boardmember fuelcellguy.
I had a TPI from a 305 and had the chip reprogrammed by Brian at tpichips.com. I told him what I had for a motor, and what I was elminating from my TPI (such as smog), and he reprogrammed the chip accordingly.
I bought my ducting for the intake from jagsthatrun.com.
I reused the stock harness. I bought the factory Helm manual and it was a HUGE help. I elimated what I didn't need from the factory harness. I highly recommend using the factory harness, going through it to eleminate what I didn't need taught me a TON about how the system worked. It really did help with my swap.

I forgot to add, but you probably already know this. You will need to modify the middle four bolts on your intake to work with your older style heads. It's not a major mod, just something to keep in mind.

[LockDoc]

Originally Posted by tranz am

awesome! then I can just use my aftermarket foam filled tank then

In the book I posted the link for the author recommends a Datsun/Nissan 280z external fuel pump. I think Autozone has them. I looked online once and I think they were $117.00.

LockDoc

[jbristo67]

Originally Posted by 71swb4x4

I am almost positive that 90 PSI is what the TPI runs at.

I bought a tank with an inline pump from boardmember fuelcellguy.
I had a TPI from a 305 and had the chip reprogrammed by Brian at tpichips.com. I told him what I had for a motor, and what I was elminating from my TPI (such as smog), and he reprogrammed the chip accordingly.
I bought my ducting for the intake from jagsthatrun.com.
I reused the stock harness. I bought the factory Helm manual and it was a HUGE help. I elimated what I didn't need from the factory harness. I highly recommend using the factory harness, going through it to eleminate what I didn't need taught me a TON about how the system worked. It really did help with my swap.

I forgot to add, but you probably already know this. You will need to modify the middle four bolts on your intake to work with your older style heads. It's not a major mod, just something to keep in mind.

It depends on how big of injectors you are going to run 90 psi will work great for a 305 or a stock 350. You dont have to modify the center bolts if you get an intake off of a 85 or 86 tuned port

[71swb4x4]

Originally Posted by 71swb4x4

I am almost positive that 90 PSI is what the TPI runs at.

I did a little research and found that the TPI runs at 35-47 PSI. The stock system will actually start at 35 PSI and then have one bump-up to 45 PSI.
Thought I should correct what I wrote earlier since it wasn't correct.

[tranz am]

Great! this is such a huge help.
on the 4 center bolt holes what exactly do I need to do to them to make it work with the early heads? do I just take a file or drill to them to them and ream them out to the proper angle or do I need to drill new ones. If I have to drill new holes is there a need to weld up the old ones? I already have a 87 + manifold so I'll just use that. I guess Im missing the mass airflow sensor on here. What are my options? do I have to run one?

Also on a different note my friend had a set of 86 + heads off a 350. Do these heads have the correct bolt angle and should I use these heads over my mid 70's heads?

[tranz am]

will it hurt anything to run more pressure than I need? whats the deal on this?
I can easily get a hold of a z fuel pump.

Originally Posted by 71swb4x4

I did a little research and found that the TPI runs at 35-47 PSI. The stock system will actually start at 35 PSI and then have one bump-up to 45 PSI.
Thought I should correct what I wrote earlier since it wasn't correct.

[tranz am]

also where the hell do I place the O2 sensor If Im running long tube headers? I think I read something that said no more than 15 inches away from the head.

[tekno62]

would this up grade help increase mpg

[tranz am]

yes! 18 - 20 mpg's from what Ive read.

Originally Posted by tekno62

would this up grade help increase mpg

[Andy4639]

Tpi factory settings are about 40 to 45 PSI. Anything more and it makes the injector over spray.

[71swb4x4]

On the fuel pressure - the fuel pressure regulator will handle the pressure, so the pump should crank out more PSI, and the regulator will back it down by sending fuel back to the tank. I have read that if your pump is too powerful, the fuel return line can't handle the extra fuel and you end up with problems.

On the O2 sensor. You should find in reading that if you use long tube headers you will want to use a heated O2 sensor. I don't know the exact distance, but I do remember reading that a heated O2 sensor will help when the O2 sensor is behind long tube headers.

On the gas mileage. I found my mileage improved a little bit, but certainly not enough to pay for the conversion. The other problem was the low end torque made it more fun to get into the pedal.

[smoky02]

Originally Posted by 71swb4x4

The other problem was the low end torque made it more fun to get into the pedal.

Maybe I'm still young...at 28, but why was this a problem?

[tranz am]

The only problem with it is when you do it in front of johney law or when you break something in the process.

Originally Posted by smoky02

Maybe I'm still young...at 28, but why was this a problem?

[tranz am]

so far Ive read quite a bit from the chevythunder.com website. I think I have most of it figured out now but still some questions remain. the biggest of which is the gas tank situation. I want to use a in tank pump and I want to use a tank that fits between the rearend and the bumper. what tank am I going to need.

[smoky02]

On my truck I used a 27 Gallon Military Blazer tank. Works great. And I picked it up for about 150. If i remember correctly.

[smoky02]

But I would recommend not getting a tank that big, the bottom of my tank sits a little lower than my roll pan. Although when I had a bumper it was perfect and you couldn't see it at all.

[tranz am]

Im looking for a small tank somewhere in the 10 - 15 gallon range. I cant remember where I read it but I know someone said something about retrofitting a tpi pump in an older tank. any thoughts on that anyone?

Originally Posted by smoky02

On my truck I used a 27 Gallon Military Blazer tank. Works great. And I picked it up for about 150. If i remember correctly.

[monte0185]

This tank might be good. its baffled and everything and it will fit in between the frame rails with very little mods. This is what im going to use.

http://www.tanksinc.com/index.cfm/pa...rod/prd113.htm

[tranz am]

looks great but at $380 its quite a hit on the old pocket book for sure. There has to be a more cost effective solution. I think a trip to the junk yard is in order. What tanks came with a tBi system That fit between the frame rails?
I know that a tBi tank will work, givin I can find one to fit the frame rails, I guess all have to do is switch out the tBi pump with a tPi pump. The question is were they baffled or not?
This is a hard one. I guess its good we are clarifying this.
If I cant find a solution maybe the only other option is use an external pump with a bottom feed tank. Such this aftermarket foam filled pro street tank. I already have this tank, just not sure if I can make it work. Will it? and does the foam act like a baffle? The summit site says "foam filling to prevent fuel slosh and aeration" so Im guessing that means it does but Im not sure how well it works in comparison to true baffles.

Originally Posted by monte0185

This tank might be good. its baffled and everything and it will fit in between the frame rails with very little mods. This is what im going to use.

http://www.tanksinc.com/index.cfm/pa...rod/prd113.htm

[smokekiki]

Tanks inc also has this.....http://www.tanksinc.com/index.cfm/pa...=cat/cat61.htmTo run Votec heads you need to have a vortec TPI intake manifold.
You can get an adapter to plug a heated 3 wire o2 sensor into the stock TPI harness. Then you can put the o2 sensor in the header collector.

[tranz am]

definitely a cool pump, but man these things are not cheep are they?
Im leaning toward using an external Datsun Z pump. these pumps are everywhere and I bet a bit less expensive.

Originally Posted by smokekiki

Tanks inc also has this.....http://www.tanksinc.com/index.cfm/pa...=cat/cat61.htmTo run Votec heads you need to have a vortec TPI intake manifold.
You can get an adapter to plug a heated 3 wire o2 sensor into the stock TPI harness. Then you can put the o2 sensor in the header collector.

[71swb4x4]

Originally Posted by smoky02

Maybe I'm still young...at 28, but why was this a problem?

You took the sentence out of the paragraph, the paragraph was referring to gas mileage. When you get on the gas pedal more, your gas mileage decreases.
If you want to convert to TPI solely for the increase in gas mileage, forget it. If you want to do it for the experience, the cool factor, and the low end torque, then go for it. I am skeptical on the 19-20 mpg estimate. I found mine to be closer to 15. Throw in a 700r4 and a light foot, and I think 17-18 is possible. Throw an extremely conservative driver behind the wheel, and then you may start to hit 19-20 mpg. But, it's tough to do, because it's so fun to drive.

[tranz am]

So Im going to need to find a computer /pcm and a prom chip.
Ive been to junk yards and I cant ever seam to find the right tPi Pcm.
is there a place that any of you might recommend to find the pcm and prom chip?
Im hopping that the Tank above and the Z pump will work.

[Andy4639]

A stock pump is only about $60.00 bucks at O-riley's. A 350 305 stock motor don't need no more than 40 to 45 PSI. The intank one will go in place of a tbi unt one. I know I have one now for 15 years and it works fine. I've said this before fab up a small gas box to fit under the cab inside the frame rails. Make it big enough for the pump to go inside of it. Put a gravity feed line off the orignal tank to it and have all the return lines and such come back to this small pump tank under the truck. Shouldn't cost that much to have one done.