Blazin4x4

Whats the pros and cons of each system? I'm still in the planning phase of my build and already have a tbi setup capable of 400 plus hp but its seems like tpi supports more power from what I've heard and makes more tq and hp because of the better atomization and intake design.

I'll be posting this in the tbi thread too to get both sides of the story.


I just thought about it last night... why put all this money into a tbi system when a tpi system can do it better and handle more power? Or can it? I don't know much about the tpi setup... Thats why I'm posting this.

I'll probably end up starving my motor if I stay with tbi... my old plan was hyd flat tappet lifters and afr's older street heads but I'm planning on a 383 with afr eliminator 195 street heads(has to stay CA smog legal), roller rockers, and mechanical flat tappet lifter so I'll be somewhere around 450-475 hp and 520 or so ft lbs N/A at least thats what desktop dyno says.

I think tpi would be the only option for that but then again you guys know your shiznat when it comes to tpi...

School me.

1989GTATransAm

iTrader: (3)

Yep TPI can support more power. Look at it this way. You have two injectors versus eight injectors. How big would the two injectors have to be to match the output of the eight injectors on a TPI system.

bjankuski

The TPI system as designed by GM will not support 400+ hp without making changes to the intake system. You would be better off switching to a Superram, Miniram or Stealthram to support a 383 with 450 to 475 HP. You could switch over to the TPI computer and wiring and then have the chip reprogrammed for your combination or you could run an aftermarket computer system.

GOY

Stock for stock, TPI blows TBI out of the water. Modified, it becomes more about what you really want. If you want something in the area of 400HP, you are going to be looking at neither. A 4 barrel TBI setup would be needed, or a SR/HSR would be needed for MPFI.

A well tuned, moderately cam'ed TBI setup with decent heads and all other factors being equal will produce a very broad flat torque graph, with more off-idle torque till about 2200RPM, then once again, more torque again from 4000+ RPM.

The same engine with a well tuned TPI setup on top would *Likely* idle better than the TBI setup, and would provide adequate low end power, with exceptional power between 2300-4000 RPM. *Hypothetically speaking* one might be able to squeak out slightly better fuel economy but that is hypothetical.

Think of the TBI setup's as "Untuned" EFI, while the TBI is "Tuned" for a specific range. If you really want anything close to those peak numbers however, GM 2brl TBI won't be able to fuel it, and TPI won't be able to supply the air. Look at the superram since you have to stay CA smog legal. It's about your only choice.

Blazin4x4

I've got a laptop, pro version prominator, and a tuning cable, next comes lc-1 wideband and ebl...

I think I'll probably stay with tbi tho... I have the holley 670 cfm tbi and holley fuel pump and with some high psi(around 25-30) it should be able to handle 430 hp plus which is absolutly fine for me... the tq will be around 500 ft lbs and since this is a 5000 pound k5 blazer tq is more important and 430 hp is nothing to sneeze at.

Kevin91Z

iTrader: (1)

I've never seen anyone make 350HP out of a TBI, let alone 400+. If you do, it'd be amazing. Two injectors just cant flow enough fuel.
Yet there are tons of 350+ RWHP TPI's out there. And the tuning on a TBI is a nitemare compared to a TPI, but I dont know what the TBI EBL is like.

Blazin4x4

so if you can't see it doesn't exist? fast 355 is making 420 plus hp on tbi. And I know other people are making the same or more. RRob, the ebl's inventor said if it can take the psi it'll can support 450 hp but bear with me here I'm not trying to run people off from posting opinions

I've done alot of reading here and it's rpm that you need to worry about not hp. since it's a 383 it'll peak at a lower rpm. Also with a 670 cfm tbi flowing 85 pph fuel is not a problem until your injectors hit max psi... I've just found out my setup should take 30 psi okay and if I use a vacuum indexed fpr it'll run like a champ.

Guest

Where's his dyno chart?

I went way past 280RWHP on a TPI with stock runners and plenum, probably could swap the base back to my ported stock base and see near the same... so you're right, gotta be careful with the 'information' out there... people have their opinions and more often than not, they're just that.

I still think you should stick with TBI given where you live. Red tape is no fun. You're gonna need as much fuel as you can get in there and run the larger TBI and hope for the best, most fail.

Blazin4x4

I didn't see the chart... I just asked and he told me 423 fwhp. Yeah I'll most likely stay with the tbi... rrob and fast355 seem to have a pretty good rep around here for knowing they're shizzle(rapper for ****) and both of em run high hp tbi's. Also this is a holley tbi that holley themselves say will support 350 hp with their recommended 13 psi and tuning... at 30 psi I don't see why I wouldn't be able to fuel 450 hp... keep in mind that is at 5500 rpm and rpm is what will determine the limit of your fueling ability. RRob invented the ebl so he has experience with hot tbi's and he tells me 450 hp should be doable with high psi... he also has worked with a 30 psi holley tbi and said it should be fine so I think there isn't really a point to going tpi for me.

Fast355

iTrader: (2)

The injectors used in the newer Holley TBIs are the same Delphi ones used in the HD truck engines. 366/427 in the Topkick/Kodiak. I have personally run this style at 40 PSI on a 305 that had a HD truck 2" bore TBI unit on it. The truck injectors are in the neighborhood of 85 lb/hr @ 18psi to begin with. 40 PSI from the stock 18 psi used on them, should push volume close to 125 lb/hr, EACH. It did idle a little rich and lumpy, but part of that was due to the nature of the cam that is in it. The TBI is a whacky design with a governor on the side of it.



PS- here are the cam specs on my 10.6:1 312. Keep in mind that this engine has 4-bolt main caps with ARP studs, forged crank, X-rods with ARP studs, hypereutetic pistons, and a balanced rotating assembly. It isn't going to come apart anytime soon.

Comp Xtreme EFI retrofit roller P# 280XFI-HR13
Advertised -280*/288* Duration
.050--------230*/236* Duration
Lift(1.6:1)--.576"/.570"
LSA---------113*
ICL---------108*

The heads are ported 2005 ZZ4 aluminum castings. In order to reproduce them, they would have about $1K into them by the time it is said and done.
Head flow is 238I/198E @ .500" lift.

The exhaust on the dyno was "2nd gen Camaro" 1 3/4" x 3.5" long tube headers, 3" pipes, 3" X-pipe, and dual 3" flowmaster 50 series BB delta flow mufflers.

The intake was an edelbrock performer RPM and a HD truck TBI unit with 85 lb/hr injectors and 32 psi fuel pressure. I ran them at 40, but had too much fuel. Brought it down to 35, then down the 32. Peak FWHP of 423 HP was reached at 5,900 rpm. Power held strong until around 6,500. At 6,600 the pull was terminated.

Here is the sound clip

YouTube - 400 FWHP TBI 312

Here is a screenshot of the unloaded 700 RPM idle from RBob's EBL. 65 MAP is roughly 10.8 in/hg of vacuum.

Guest

Have that same cam, in a 350. Runs mid 13's in a heavy car with zero traction, got 21+MPG with a loaded vehicle, 3 people, and the aerodynamics of a brick. Probably would do better with a tune, fuel is ok but timing is likely a little off.

Fast355

iTrader: (2)

This same shortblock with a milder Crane roller cam and heavily ported 081 TPI heads, produced a 15.04 @ 96.7 in a 5,300 lbs G20 van. With only a 3.73 gear and 2,800 RPM yank converter. 301 RWHP through the cut-outs.

I have plans for a pair of Dart 180s and a GM Hotcam into my current bolt-on but otherwise stock 350 TBI pretty soon. With only 177 RWHP, I feel like I am missing something.

3.8TransAM

Also as Fast355 knows and Rbob himself designed, the EBL vs. a stock TBI is not even a comparison.

The setup and rebuilt code allow the TBI to do all the stuff you couldnt with it as it was designed from GM originally.

Its the only reason I've considered buying something TBI for a beater. Prior to the EBL I wouldnt have wasted my time.

Go do some research on it, its a fascinating little setup

later
Jeremy

Fast355

iTrader: (2)

Keep in mind that my 301 RWHP was made WITHOUT the EBL. Using the $42 code in a 7747 ecm.

Blazin4x4

it's already been done man...I am the same as you... ebl is what is keeping me from going mpfi. If I ever want to go 4bbl or supercharged I have that option as well as the ease of use with wideband and the 3 bar map.