Cascade Crew

[91RSVert]

Ok, I'm new here, most of you dont really know me. So background before info here for the poll.

I'm highly in debt, but love tinkering with cars. So anything I do, I either have to save for a long time, or buy used parts, and do it the hard way/cheap way.

So, I got this new vert with plans of swapping to TPI. While hunting on TGO for a "TBI to TPI" how to thread, I came across another thread in TPI section of "use OBD2 SFI on your TPI". WHAT?!?!

So I read it, like it. One guy IIRC got 5hp, 3tq, and 3MPG just from the swap. NICE. Can modifiy for tire size and gears, EXTRA NICE.

But as I read, I gotta get this, n that.. all gm parts I can get used, and MUST learn how to edit ECM code. I have ZERO experience with ecm code, and you gotta get EFI live which is *gasp* 750 bux.(unless someone knows another program?)

So I got my TPI parts, except pump, cables, and my harness! Should I get the SFI harness n other parts and swap right to SFI? Or just get the TPI factory harness and make it look all factory and learn the 7730 bank fire code?

[Dewey316]

Just so to make sure I am looking at this right. You looking at circa $1000 for a computer system. Any reason you are set on using GM stuff at that price point, there are several other options out there, that will have some features that the GM stuff won't have. Then again, the GM systems have stuff that the aftermarket doesn't. I think if it was me, in your position, I would go aftermarket. I am really looking into the 034 system myself. But, if you are really tight on money, maybe something like megasquirt would be the way to go.

(the real honest opinion here, is that I wouldn't bother going from TBI to TPI myself. with the EBL system for TBI you can tune really easily. I have actualy had suprising good results with TBI, and it isn't THAT bad to tune.)

[91RSVert]

If I stick with TPI 7730, I have alot of stuff already. I need harness, chips, burner device. I already have the ecm(will want a backup), moates g3, program and aldl cables.

Other then the program, price is about the same either way... unless as you said, I go full aftermarket. Id like to kinda stay gm because they actually are reliable, plenty of parts.

TBI, Ive never really liked. I know bolting on the TPI is about instant 40-50hp. What needs to be done to TBI to get that gain, then whats left to do? Just seems like TBI has a much lower limit then TPI.

Also, for me, not everything is about power, its about effiency. Now I do know TBI is easier to work on then TPI.

[Dewey316]

Where are you seeing numbers that TPI will pick up 40-50 HP. With an aftermarket carb manifold (what, $150-$200), and exaust work, is where all the gains are. After that it is the heads. Without changing the cam and heads, I doubt you will really pick anything up with TPI. You will gain yourself the torque spike @ 3000 rpm, but nothing other than that. there is no magic in TPI, you are limited by the cam/heads that are on the motor. Fix those, and you will do alright.

FWIW, I made 220hp to the wheels, with 206/216 .447 lift cam, a wieand carb intake, and 416 casting heads, still using the stock TBI unit and injectors. I also had a torque curve that you would die for, it held within 5 ft/lbs from 1500-5000 rpm. It was completely flat.

without the heads, i put 208hp to the wheels, with nothing more than the cam, and the intake manifold (and headers/catback). TPI is not going to fix an L03. TBI isn't the problem on those motors, it is the pathetic cam (i have heard it is something like 172* on the intake side ), and the restrictive heads, and 2" exaust manifolds.

[91RSVert]

ok, I dont have a LO3, I have basically an LO5, and a non stock cam.. that I dont know what it is.

an LO5 is 205hp correct? An L98 is 245hp correct? So 40hp from TPI and I am sure a different cam, and ecm.

Not sure what heads are on this motor. I plan to look at that in the next few weeks. Id like at the same time to attempt to see how much the rockers travel to see what lift I have. Anyway, I would like to go to the vortec heads down the road.

Not sure what I am going to do with exhaust, as I have had nothing but problems from rides that have headers on them. Catback is already installed.

[Dewey316]

That 40hp is not from the TPI. The L05 has swirl port heads, compared the the pretty descent heads the L98 has. The cam's are goign to be quite a bit diffrent.

What version of the L05 do you have, there are several diffrent ones. The ones from the cop-car had IIRC the same cam as the L98, but still use the swirl port heads. If the L05 is from a truck, then it has a flat tappet cam, (which is about 194/202). If it was an L05 from a car, that was not the cop car package, then it has the same stupid cam as the L03. Those L05's were only rated at 180hp from the factory.

You may pick up some power, from a slight effeciency diffrence, but just putting TPI on and L05 does not give you L98 numbers. I would wager with you, that at the BEST if you pick up power it is 10-15hp. Probably not even that.

[91RSVert]

Other then it being a 5.7 block, and having TBI on it, I have no clue what I have under the hood. If it has a flat tappet cam, the whole motor will be pulled and something else put in its place.

am 90% sure It has a cam in it. I have never heard a stock cam lope like this at correct timing. And yes, its at correct timing.

Either way it goes, its getting TPI on it, part of the stuff I already have, rest is on it way. The TBI already has a buyer.

I'm just trying to decide if I should go with OBD2 SFI, or OBD1 bank fire.

[Dewey316]

SFI would be preferable, as it gives you a lot finer control. There is a reason why all the OEM's have gone to SFI. If it is between those two options, and both are viable options from a budget stand point, go SFI.

[91RSVert]

Found out a swap meet is coming up soon, will figure out which heads I have and see about getting some advice on which heads to look for.

Then possibly also look for sfi swap parts??