Hey all. So I've made a thread (or two ) about this before, but it seems I'm finally at the point where I'm ready to start hunting down what I need for a motor swap (i.e, some time and funds, plus a workspace will be at my disposal).

Overall, my eventual "goal" is nothing too crazy. Something like a 325-375 FWHP build. A fun street set-up basically. However, in the meantime, I'm looking to run a more conservative tune, as I'm still running a T5 and such. Maybe around 250 hp.

My plan was to grab either a lower mileage used, or possibly reman L31 longblock assembly, since it seems to be the logical route for budget gen 1 SBC builds.

Most of the questions I still have are tuning/emissions related, which are as followed..

- I can't seem to find bore size specs on the GMPP TBI vortec manifold. Some say it's 2'' and others 1.75". If the latter, can it still support my eventual power goals w/out boring it out?

- Another option I've been told of is getting a carb manifold and a TBI adapter plate to run TBI. Is there any way for this setup to pass smog, since there's no EGR provisions and such?

- How does an EBL Flash TBI set-up compare to a stock ECM TPI setup as far as ease of tuning and potential power goes? It's my understanding that a built TBI set-up w/the EBL upgrade is still a considerably more cost effective set-up than TPI, but I'm hoping someone else can confirm that (w/out turning this into a TBI vs TPI debate, lol).

 

my GM Performance TBI intake was 44mm arround 1&3/4". I bored out the intake to 46mm I went with a 46mm TBI built by SRP. Sean did a great job and was very patiance dealing with me and got me what I need. But get ready to drop over $400. I also opted for an EBL. I havent done the swap yet but everyone here are very helpfull and will walk me through it.

 

Carb Manifold-- You can run an adapter plate and you might have to tap a hole for the one of bolts that hold down the tbi unit. Disclaimer: You might have to. I went with the GMPP tbi Manifold, it was a bit more expensive and it only has one vacuum port in the rear of the manifold...it seems to have less ports than the stock manifold had.

EBL Flash-- I have no regrets buying the EBL. If you follow the instructions that RBob provides and read the discussions found within this forum, you could find yourself having a bit of fun in finding some extra power in your TBI camaro. Also...the EBL can run TPI bins on it, so if you ever switch over to tpi you can keep the same ECM. I believe buying an EBL is worth due to it's ease of installation, it's included software, and that you can flash in your bin's from your connected laptop (no additional equipment is required besides the serial cable and the adapter that plugs into your laptop)

 

Ok, back in here. I'm ready to start acquiring parts I need for my swap. Motor-wise, it's looking like an L31 Vortec longblock, but w/machined heads/upgraded springs for higher lift, in order to support an LT4 cam.

I have the chance to snag up a TBI Vortec intake manifold. And I'm looking into getting EBL Flash. I could also pick up a 454 TBI w/the manifold. The question is, is it the actual 454 TBI unit itself that I will need to feed this engine, or do I just need the higher flow injectors/to bore out the throttle body/intake manifold? Just asking what I will need now so I don't buy anything that I don't need.

I also know I will need a higher flow fuel pump to feed a motor like this as well. What's the best choice to go with?

 

You could run the injectors you have already at higher fuel pressure. Monitor your DC and keep it at 85% or lower. You could always swap in larger injectors later.
I would use a TPI fuel pump.

 

Really? I heard that the stock 305 injectors only have a 50-ish lbs/hr flow rating. I'm aware that you''ll need to bump up the fuel pressure for any performance friendly TBI setup, but I remember hearing that generally speaking, it's better to run bigger injectors with a small increase in fuel pressure vs small injectors with greatly increased pressure, as it's very hard on the injectors and will rapidly decrease their lifespan/reliability, is this true?

Do the 80 lbs/hr injectors hook up to the small block TBI system, or do you need the 454 TBI assembly? And any particular reason for a stock TPI pump vs an aftermarket pump?

 

The BBC injectors drop right into the SBC pod.

The reason for a pump such as a TPI unit is returning the unused fuel to the tank. At low fuel pressures pumps move a lot more fuel. The TBI unit becomes a restriction. This causes the fuel pressure to be too high at the inlet side of the TBI unit.

So using a TPI or a 190 LPH fuel pump you are able to have a proper fuel pressure. And control of it.

As for smaller injectors at higher pressure, or larger ones at a lower pressure, six of one and a half-dozen of another. It you can use injectors that when run in the 18 - 22 psi range provide the required fuel. You can also vacuum reference the FPR.

When combined with an EBL ECM it will provide better driveability.

RBob.

 

1994-1995 GM went to 45 lbs inj's at pressures of >30 lbs. I am uncertain if they are better constructed for the higher pressures. DC Trumpet would know as would fuel injector connection.