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TBI Throttle Body Injection discussion and questions. L03/CFI tech and other performance enhancements.

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Old 02-11-2006, 09:24 PM   #1
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Fueling Vortec Tbi 355

Just finished a vortec 355 tbi motor for my neighbor. Motor has crane cam 212/218 duration. Holley 670 tbi, gibson headers, dual exhaust, vortec heads.....Sent it up to Carolina Auto Masters this week and had Jeff tune it. He pulled 40hp out of just the tune but it is still only making 165 to the wheels. I started looking at the graph and right around 2800 it goes way lean. I havent been able to talk to Jeff yet but when the truck was picked up I guess he said he couldnt program in any more fuel. My question is what size injectors come stock in the Holley 502-9, and what would be a safe size to step up to. I already bumped the FP up today which made a big difference but I would like to get close with injector size and fine tune with FP and tuning.
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Old 02-11-2006, 09:38 PM   #2
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My suggestion is to ditch the holley, they prove to be nothing but trouble. For one the holley injectors can't tolerate raising the fuel pressure too much more. I prefer the BB Chevy TBI as you can pick them up everywhere. The 454 injectors should satisfy your engines thirst for fuel. I run 68# police/van 350 injectors at 32 psi to fuel my 305.

165 RWHP isn't that much, like you said. I would think that the engine you have there should be more like 230-240 RWHP.
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Old 02-11-2006, 09:40 PM   #3
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Edit.

My STOCK L05 put down 145rwhp, after that much work I'd be livid.
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Old 02-11-2006, 09:42 PM   #4
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Kinda stuck with the holley now, your stated rwhp numbers are what I expect once everything is sorted out. The AF ratio looked good until 3000 then went way above 15 to 1. I had the LM1 on it today after the FP adjustment and it looked better. Any suggestions on injector size?
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Old 02-11-2006, 09:45 PM   #5
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Ive been doing TPI and LT1 for awhile now so I wasnt really that shocked at the numbers after doing this much work. I new the tune was going to be way off, but Jeff has worked wonders on a couple of other cars for me and some friends. Just need to get it the fuel it needs.
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Old 02-11-2006, 09:54 PM   #6
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http://www.cranecams.com/?show=brows...tType=camshaft

I am going to assume that this is the cam that is in the engine. Combined with a good intake, good air cleaner setup, good exhaust and shorty headers, vortec heads, 670 cfm, and the above cam. The engine I am modeling is .030" over and a typical 9.5:1 compression.

I get 293 HP @ 4,500 and 371 ft/lbs @ 3,000. That is roughly 250 RWHP and 325 ft/lbs at the tires.
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Old 02-11-2006, 09:59 PM   #7
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What program did you run that on?
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Old 02-11-2006, 10:00 PM   #8
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Quote:
Originally posted by TierAngst
Edit.

My STOCK L05 put down 145rwhp, after that much work I'd be livid.
My stock 180,000 mile 1983 305 converted to TBI(holley projection intake, a 454 TBI, 350 injectors, and lots of tuning), with a good exhaust made 181 RWHP @4,200 and 268 ft/lbs @ 2,800.

I would imagine that it will get MUCH better after some more tuning.

I suggest based on 300 HP, .45 BSFC, and 85% duty cycle to go with injectors that are rated around 80 lbs/hr. Doesn't really matter how you get to 80 lbs/hr, just that it needs to be around 80# each.

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Old 02-11-2006, 10:01 PM   #9
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We already made that torque number but just when the HP should start picking up the fuel fell off.
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Old 02-11-2006, 10:04 PM   #10
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Quote:
Originally posted by likeistoleit
We already made that torque number but just when the HP should start picking up the fuel fell off.
The 325#? I could imagine that you ran out of fuel about there. Most of the time you can hear it, the engine just goes DULL, the exhaust tone changes, and it quits pulling My guess is that you will need to increase the pressure quite a bit, (keep in mind the Holley's tolerance of this and a typical TBI fuel pumps abilities) or upgrade to bigger injectors($$$ and not much choice).
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Old 02-11-2006, 10:04 PM   #11
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You have a version newer that I do of the program. As far as the injectors that is what I was looking at, just wanted a few people to chime in who have already played this game so I didnt waste any more money on injectors.
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Old 02-11-2006, 10:07 PM   #12
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You pretty much nailed it on the performance and sound. So what is everyones take on fuel pump upgrades, what point does it have to be done. I am pretty much sold on ordering bigger injectors rather that putting the pressure throught the roof, just not decided on what size yet.
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Old 02-11-2006, 10:07 PM   #13
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Quote:
Originally posted by likeistoleit
You have a version newer that I do of the program. As far as the injectors that is what I was looking at, just wanted a few people to chime in who have already played this game so I didnt waste any more money on injectors.
I played with the Holley TBI long enough to put it on Ebay and get rid of it. The injectors would stick open on occasion causing the engine to flood. The TPS would not hold its adjustment either.

I am in the belief that the Holley will cause you much grief and frustration over the long run.
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Old 02-11-2006, 10:10 PM   #14
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Quote:
Originally posted by likeistoleit
You pretty much nailed it on the performance and sound. So what is everyones take on fuel pump upgrades, what point does it have to be done. I am pretty much sold on ordering bigger injectors rather that putting the pressure throught the roof, just not decided on what size yet.
If this answers your question, I have seen the pressure on stock engines drop down to like 8 psi on long hard pulls while towing, w/ the stock pump.

I have a GMC Jimmy that I put a 3.4 into, the same pump as a V8 truck. I have an O2 sensor connected to a cheap A/F ratio gauge. Under WOT, with a trailer, going up a good hill, I saw the gauge go from the green, to the yellow, to the red (lean) due to the fuel pressure dropping away. When I saw it drop into the red, I started letting out of it, it then proceeded to start bucking like it was running out of gas. Guess what, it was. The filter, strainer, everything checked out. Swapped the TPI pump in place of the TBI pump and it never did it again.

I ALWAYS put a TPI pump in the tank of TBI cars and trucks when I change them out. It is just a better pump. I run a Master Brand, Ford style frame mounted 80s truck 190 lph fuel pump on my van. It has pushed me to 300 RWHP just fine.

Last edited by Fast355; 02-11-2006 at 10:14 PM.
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Old 02-11-2006, 10:13 PM   #15
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Yeah, seems everyone here is of the same opinion as you on the Holley. As I said it isnt my truck, it is my neighbors and he ordered all of the parts before I had a chance to do any research. When you had injectors stick did you have larger injectors or do you think it was just because of the high fuel pressure?
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Old 02-11-2006, 10:15 PM   #16
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Would the stock tpi in tank be a drop in for the TBI pump?
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Old 02-11-2006, 10:17 PM   #17
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Quote:
Originally posted by likeistoleit
Yeah, seems everyone here is of the same opinion as you on the Holley. As I said it isnt my truck, it is my neighbors and he ordered all of the parts before I had a chance to do any research. When you had injectors stick did you have larger injectors or do you think it was just because of the high fuel pressure?
I hear you on the not being your truck situation.

I was running about 20 PSI when it stuck,
Also take note that the Holley injectors will stop spraying a cone when the pressure approaches about 23-25 psi. It becomes just like 4 fire hoses spraying down the TBI.
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Old 02-11-2006, 10:19 PM   #18
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Quote:
Originally posted by likeistoleit
Would the stock tpi in tank be a drop in for the TBI pump?
Was on everything I have put it in. It is readily apparent what needs to be done between the two pumps just by looking at them. They share the same outlet location, wiring connecters, strainer, etc. Almost look like the same shell, just different guts.

Some TBI pumps had a weird connector on them, but that was the high pressure systems of 1994-1995.
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Old 02-11-2006, 10:22 PM   #19
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Well, looks like we will order the larger injectors and try to keep the fuel pressure down. I just checked out Holleys web site and they said the now have new injectors, dont know if this may have fixed some of the problems you had or not.
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Old 02-11-2006, 10:27 PM   #20
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I think Delphi now supplies the injectors for Holley. I am guessing your neighbor picked up one of the newest TBIs from say Summit or Jegs. I can only hope that you have a Delphi equiped unit. If not, the ones you are ordering should be delphi.

What intake is on this truck?
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Old 02-12-2006, 09:23 AM   #21
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Correct it is one of the new ones, he has the GM performance intake on the truck.
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Old 02-13-2006, 02:25 PM   #22
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i believe the Holley injectors are rated at 20 lbs. GM rated 12 lbs. so a 80 lb Holley is a smaller inj than the 80 GM. FYI.
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Old 02-13-2006, 09:47 PM   #23
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Well, spoke with Holley today and they said that the injectors that came in the TB are the largest the sell. They also recommended bumping up the fuel pressure to around 21 psi. I am taking the recommendation on the tpi pump and following the install will be going back to see Jeff to get the tune sorted out. Ill post numbers and results when finished.
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Old 02-14-2006, 09:08 AM   #24
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my Holley catalog at home(2003?) has 80 lbs listed. i discussed with them the idea of swapping out the standard injs in a 670 tbi to 80 lbers but they would not do it. go figure. guess they wanted me to buy the 4 inj tbi set up ?
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Old 02-14-2006, 01:41 PM   #25
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I would say drop in a new pump, TPI pump or Walbro 190 (which i would go with at about 85 bucks) and see where you're at. Even though you raised the pressure on the injectors now, I would bet they dropped some under load. Get the pressure up to around 21 like they suggested and check the wideband, if that's sufficient all the way through your RPM range then you're good to go. Otherwise I'll show you what I run on my car...

Holley 670 with GM injector pod with BBC injectors in it. I like this route.
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Old 02-14-2006, 05:10 PM   #26
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Quote:
Originally posted by BronYrAur

Holley 670 with GM injector pod with BBC injectors in it. I like this route.
Exactly what I plan on running in the future. (Since I already have the unit and some GM injectors)
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Old 02-14-2006, 05:10 PM
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