Well I have a GM performance Vortec 350 that was advertised at 330Hp. It had a carb on it origanilly and I want to change it to TBI. I have found an intake also GM Performance pretty spendy tho. I was wondering what TBI I should use.
1. The 305 one I have and just put bigger injectors in it?
2. A unit off a 350 and just rebuild it?
3. A Holley
4. Maybe one from a 454
I am putting headers on it but it is going to have all the smog equiptment on it.
I am going to do all the proper mods to replace my 305 with a 350 and burn a custom chip. I just don't know which TBI unit to get. Does anyone else make/rebuild one for my applacition? Who should I get a hold of. I know you all will have the answers. Thanks I love my TBI. I normally would have kept the carb and went old school but once I ironed out a couple little problem it has been trouble free and my wife can drive it. And I'm getting 20mpg city it just is a dog and the 305 has 164000 miles on it time for a 350.

 

330 hp with a carburetor no computer...

To run a tbi with that same engine your going to need a way to tune your computer for one. So Dynamicefi.com is your best bet. Your going to need a 2 inch bore throttle body, with injectors that can spray a lot of fuel.

To give you a for instance. I have a 355 aluminum headed engine. I run the holley tbi and I am running out of fuel. I have the ebl flash computer system but I dont have enough fuel supply. I am thinking about either converting to carburetor or going to a 4 bbl tbi unit with 4 injectors to provide me with more fuel. at that point I wanna go ahead and get teh self tuning ecm also. So I am looking into the holley self tuning HP, or avenger series with a 4bbl tbi and self tuning ecm. I'd look into that too but it is going to cost you 2k. You also dont have to buy the gm vortec tbi intake. You can buy a carb vortec intake and run a 2 bbl tbi adapter or if you decide to run one of these holley, fast, msd self tuning setups they bolt right on where the carb. would go.

Good luck

 

Consider the vortec 2 barrel carb intake with adapter. 7.4L TB from truck. TPI pump. 75 lb injectors at about 24 lbs FP. You will need a reg that handles over 20 lbs FP.

Why not go MPFI ? Not that much more $$$ is it?

dynamicefi has an ECU that good for beginners be it MPFI or tbi.

 

http://www.cfm-tech.com/gm_tbi_camshaft_heads.htm

 

I see that info. One. And I think..wow I dont need more injectors...but I guess I do. lol

 

dctrumpet sells rebuilt GM TB units on ebay for much cheaper than a Holley TB. Like mentioned earlier, you will need something to tune it with and a bigger fuel pump though.

UnderCover I forgot to mention to you previously, Holley sells an 85lb/hr (@ 21psi) injector for their TB's. Much bigger compared to the 65lb/hr (@ 21psi) injectors that come with it.

 

I have the 85 lbs at 21 psi..

So I picked up some 454 injectors out of an 89 the other day. I am going to double check the #'s on them. If they are 80#'s at what that 13 psi that is more fuel. I actually had some misinformation so I think with those injectors or more fuel pressure with the holley's I can get what I need to get out of it.

 

The 80 lb-Hr injectors will work well past 30 PSI. You'll need to run VRFPR (Aeromotive 13301) - at idle fuel pressure should be low since engine fuel demand is low, but at WOT (when manifold vacuum is low) fuel pressure should be at its maximum. EBL is you best bet of getting this engine's fuel demand under control. You 'll also need block of plate and TPI FP in the tank.

//RF

 

Just going off of the EBL utility, the 85lb injectors at 21psi will support over 400hp. I'm pretty sure you're not making that much power with a mild cam and those heads (assuming I'm looking at the right ones). Something just seems off with your fuel issue.

Sorry for the thread jack.

 

Yeah. Rbob and I did the fuel thing. The formula we cam up with is that it would support 300 hp at that level. I figured that was suffice as I really dont think my engine is make 1 hp per cubic inch. But I guess it is. But to not thread jack anymore No more replies in this thread. PM me! haha.

 

God now I am really confused. I am not sure what to do about the fuel pressure. How much does the pump put out? I don't even know where it is. I am assuming in the tank. Doesn't the tbi have a built in fuel pressure regulator. Do I just put a stiffer spring in it? Is it worth buying one of those rebuilt a ported tb's off ebay? I just don't want to cut any corners I want it rite. I'm not stupid I am just new to messing with a tbi. Throw me a carb and no computer and I am all over it.
I red that artical from that link one92rs posted and it is very inforative. I think their prices are high. I just hope I didn't make a mistake with this motor. Maybe I should just keep the carb and get rid of the computer. I allready have everything for that except the headers.

 

Well you deffinately wanna have an adjustable fuel pressure regulator. whether you modify the stock regulator. buy one to into stock throttle body or buy an upgraded throttle body with regulator.


I think you deffinately want a ported tbi or a 2 inch tbi unit off of a chevy 454. those are cheaper options than buying a holley one.

you deffinately wanna find out which way you want to tune your car. dynamicefi.com is my choice...

fuel pump supplies volume. regulator determines pressure. You will be fine with the tpi ac delco pump. it is located in tank. proper way is to drop rear end and then fuel tank.

tbi can make just as much power as carb with better fuel mileage. but it is going to take more time to tune it in right.

good luck to you

 

The VRFPR stands for vacuum referenced fuel pressure regulator. At idle engine does not need too much fuel. So VRFPR sensing high vacuum in the intake manifold drops fuel pressure to about 10 PSI at idle. When engine under load vacuum drops and fuel pressure increases. Typical fuel pressure change is about 10 to 12 PSI (i.e 12 to 25 PSI). This is needed to keep injector pulse width, at idle, above 1.2 mSec. A shorter pulse width is not possible due to injector plunger inertia. This allows to use much larger injectors without going too rich at idle.

In tank FP should be able to provide 30 PSI+

Leave carb in 20th century history books.

//RF

 

It's starting to get clearer now. Can I just mod my TBI and add 454 injectors with an adjustable fuel press reg. Or should I buy a 454 one and go from there? Where do I get them. Thanks UnderCover89TBI I take your input very seriously as I do with everyone here.

 

RF that fp regulator sounds like the ticket so how do I go about getting one and hooking it up?

 

Yes, I'll post layout details later tonight.



And another one

 

RF, do you bypass (or remove altogether) the regulator on the throttle body when you use your adjustable FPR? Just curious how that works.

 

You'll have to remove the fuel regulator cover that centers stock FPR spring and rubber diaphragm. In their place a flat machined plate is bolted in using stock four machine screws. This is what it looks like - Ebay listing 260732672814

//RF

 

Stock VRFPR works good too https://www.thirdgen.org/forums/tbi/...rfpr-pics.html

 

show's that part not available for purchase anymore

 

Well I have been looking for a TBI unit. I found a couple ones from a 454 but there not cheep. They want over 100 bucks for them and they will need to be rebuilt and that will cost around 150. Now I have a line on one from a caprice cop car. He is willing to trade for the dist that cam on the motor I bought. It has no name on it just has DST1895 w/ BN10J4 under it machined in the bace under the cap. It apperes to be machined w/very crisp edges. If any one can help me identify it that would help me a lot. I can also buy one off ebay they say is ported what ever that means. There spendy too. A turn key Holley is around 500. I just want the one that will work the best.
Now on to the FP issue. If I need higher pressure don't they just sell springs to raise it? I saw some where some one had some special injectors for sale and it cam with a spring that raised the pressure to 14 to 15 but you say I'll need 20. I say stiffer spring. After all that is pretty much what an adjustable one does is stiffing the spring.
I have so many questions and all you out the have been great us car guys stick together.
Please help a guy out.
THANKS

 

Yes, keep in mind that to support the higher pressure a stiffer spring rate is required.

From my experience with 55 #/hr injectors, up to 18 psi works ok with just a tune. After that, rich idle issues start to appear.

If using VRFP, the no brainer would be to use EBL flash, it has the related fueling tables. The stock ECM lacks this feature. .

http://www.summitracing.com/parts/JET-61500/
Can also easily mod the stock one for VRFP and use stacked shimms to achieve desired FP.

Just pointing out an easy and overlooked option.

 

Thanks for all the advice. Now a couple more questions. I am planning on going with Caprice cop car injectors. They are cheep from Rock Auto. Do I need a different body or can I use mine? I just rebuilt mine and it is running great. What about this fuel pressure issue? Do I need more to run those injectors? I checked at Top Down Solutions and didn't see the springs to increase the pressure. Summitt has an adj one but it;s 83 dollars and it is just going to be cranked all the way down to get 20#s. I'd hate to spend 83 dollars when I can just buy a spring.

 

Topdownsolution spring http://www.top-downsolutions.com/pow...ress-regulator)

Dctrumpet TBI parts (including FPR springs) http://tbiparts.com/

Your TB pod will work, phisically the injectors are the same, just the flow rate changes.

You say you need to feed 330 fwhp.
65#/hr @25 psi, 68#/hr @23psi, 75#/hr @19 psi or 80#/hr @17psi, should do the job.

Up to you now to investigate what flow rate the injectors from rock auto provide.

 

To get to 330 HP you'll need

330 HP at a BSFC of 0.45:

330 * .45 = 148 pounds of fuel per hour (#/hr).
Then factor in a maximum of 85% duty cycle for the injectors:

148/ 0.85 = 174.7 lb/hr or Per Injector 87 lb/hr

So a pair of BBC 80 lb-Hr at 13.5 to 14 PSI will work OK if you have (watch injector pulse width at idle) them.

Alternatively if you have cop car injectors (64 lb/Hr) then you can bump fuel pressure up to:

SQRT(87 / 64) * 13 = 15.2 psi.

Based on above calculations:

1) contact Dctrumpet at TBI parts and get stiffer spring - you do not need VRFPR for 330HP level. His springs are very accurate (depending on the tab position I get consistent 17 PSI)
2) 64 lb-HR 'cop injectors' are a better choice. At slightly higher FP their spray pattern will be better vs. 13 PSI.
3) Expect to custom tune your combo. Stock calibration will be just good enough to get you going.
4) Save funds for EBL and WBO - these will be needed to get that performance.
5) GM TBI injectors can be used in any (Rochester Products 220, etc) TBs.


Concerns.

1) Rich idle - with stock VE table you may end up running very rich at idle BLM=108. The 64 lb-Hr idle pulse width should be around 1.5 to 1.7mSec. At 15.1 PSI (I am taking a wild estimate) the pulse width will need to be slightly shorter 1.4 to 1.6 mSec -still well with injector physical capabilities.

2) AE and PE - these parameters will need to be adjusted. You'll need WBO (ZT2 from Zeitronix or LM2 or TT-1)

3) Cold start - may be too rich. You'll have to try.

//RF

 

Hey guys!

Sorry it's been so long since I've been on this board. If you need anything or have any questions please feel free to contact me.

Thanks for everything

Sean

 

Sorry to thread jack. So GM TBI injectors will go into a holley throttle body?

 

Nope.... GM only TB's

 

Typical. Lol. Thanks. Guess I should either go back and get the whole 454 tbi and replace the holley one or something else.

 

So I can just buy the caprese injectors and use my body?
Do I run the stock fpr spring?

 

You can use the TB you currently have. It may not flow sufficient CFM. That will show in datalogs as lower MAP reading. If that proves to be correct then you need to bore them or swap in 7.4L TB. 65 lbs injectors should be OK at higher FP.

 

Yes you can, the injectors will fit.
The stock FPR spring will not work, since you will need around 25 psi of fuel pressure with those injectors.

 

This is just getting way to confusing for me. The Caprise TBI unit I was going to get fell through. Can I just get away wit a TBI unit off a 350 with the stock fpr spring and every thing? How do I get 25#s fp? How much does my fp put out? and so on and so on. Should I just buy a Holley?

 

Give this a read:

https://www.thirdgen.org/forums/tbi/...od-holley.html

It may be the direction you want to go.

 

Thanks. I was actually reading on that thread. I just might get a whole 454 tbi from the junkyard and do ultimate tbi mods to it. I dunno. I dont like having my car down for more than a day at a tim since its my daily driver. but I might just rent a car for a few days so I dont have to rush.

 

The ultimate mods don't really apply to the BB TBI. I guess you could shave you're throttle shafts but not really needed unless you need the extra CFM. Keep in mind unless you're intake is already bored or your adapter plate is oversized you will have to inlarge to accommodate the 2" bores on the BB throttle body.

 

305 and 350 TBI TB's are the same size, mainly only the injector flow rate changes, some vacuum ports and sensors may be a little different too.
If you keep your 305 LO3 TB and put in the caprice injectors, you would have the same TBI as a 305/350 TBI Caprice.

The stock 305/350 TBI TB will be a little restrictive on the 330hp engine and probably cost you around 30 hp, but that is not a problem because 46-50mm TBI TB's are available. 46 or 50mm, either will be good for that 330hp engine.

For a 330hp engine you will have to change the stock 305/350 TBI fuel pump anyway, the AC Delco EP-241 (stock 305/350 TPI pump) is a good and common upgrade in these situations.

 

can I run a 350 TBI with stock spring in it? They sell TB,s on eBay that have been ported but they say their only good for 260 Hp. Where do I find a 46-50 mm TB? I have an email out to CFM-Tech on theirs. So I will need a new FP either way? I just am scared of doing that job. To have it done in my 2002 Fire Bird cost 900 bucks but the pump was over 300. How much is the pump from AC Delco and where do I get it?
Just tell me what to do and where to get the parts?
Just to go off track for a second. Should I eliminate the emissions control stuff all together? I don't have smog where I live. I already bought the GM intake but I can sell that no problem and get a non-emissions one and the headers are allot cheaper. I have an exhaust guy that will make me exhaust and get rid of the cat or hollow it out. I am at an in pass but I have time my motor is running great.

 

Well the fuel pump is not 300 dollars like the 2002. The pump and strainer should cost you around 70-100 bucks total. You ABSOLUTELY have to upgrade your fuel pump.

Even on a 100% stock engine. They benefit from a fuel pressure increase. So you have to have to get some sort of fuel pressure regulator for your engine.

You don't neccesarily need the emissions stuff. But you will need to have that stuff programmed out of your chip, or whatever your going to be using for tuning. Well EGR I mean.

Other than that you can remove your smog pump and hoses and plug everything up and be fine.

 

I have a bored out intake. I have teh holley tbi on there now

I am just thinking I need BB injectors really. So might as well get the whole gm tbi unit. I'd go ahead and do the ultimate tbi mods if I was doing it because that is how I roll. Lol. Not just for more airflow but for smoother air flow. Thanks for your help.

 

So I should get a GM FP for a TPI? What kind of pressure do I need and want? Should I just get the 454 TBI unit complete or can I get away with using mine? What FPR spring should I get? Shouldn't a stock 454 one work? Is it just better to run a higher pressure? Do the injectors work better? I hope I here back from CFM-TECH they seem to have the complete package for my specific motor.
I really appreciate the input and I hope I am not bothering you to much.
So it wouldn't be to beneficial to delete the smog system? I already have the intake and some headers all lined up. Should I gut the cat? I know I should ask these questions in a different form but I am trying to keep it all in one place and I value every one's opinion and knowledge in this form since we are all in the same boat with the TBI system

 

No, replace it with à 3" highflow cat.

 

tpi regulator wont work

 

i would

You will need to dtermine that once the motor is running. Based on inj size you chose. you will nee 88 #/hr of fuel for 330HP.

You could try your existing TB unit and injectors but they may prove to be too small. Try the stock 454 TB and spring. There are two 454 springs BTW. High pressure is not necessarily better. Use what you need. No more pressure. I am sure CFM-Tech can help you.

 

I wouldn't buy anything from cfmtards. Mostly BS operation. Bad info on that site.

These guys actually do the work for the tards,

http://www.rvmorsemachine.com/product.htm

 

Well I think your rite xch3no2. It's been 2 days and CFM Tech hasn't gotten back to me so they don't get any of my money. This RV Morse looks interesting. Their web sight sucks so I have an email out to them. I just need someone to tell me what to get. My head is just swimming with all the info I have gotten so far. I am just confused on what to do. I really appreciate all the great input. It sounds like to me I need a new FP, an adjustable regulator that I am not sure where to set. I thing the tuner will help me set that. Now this is where I am unclear. Which TB to get and what injectors to use. No one has said anything nabout a spacer are they as good as what they say they are? So far RV Morise is the cheapest if they reply they have my business.
Now about this 3' high flow cat. Thats better then just rodding out my cat? Should I go 3" exhaust from the headers back?
ONCE AGAIN THANKS TO EVERYONE
if it wasn't for everyone mhere I would have really screwed up.
BTW xch3no2 I'm near Portland are you close by?

 

Start at the pump, TPI pump is popular, and will get you going.

R.V.'s 46mm TB is the ticket. I would use injectors that provide necessary fuel between 18-35psi, # 17084327.

Remote regulator may come later. For now make yours adjustable & get Sean's spring.

Keep your emission system intact, 2 1/2" pipes for duals.

You are most likely to see me at the Woodburn Dragstrip.

 

Well I think I'll go with the TB from RV Moris and what do you think about a chip from TBI CHIPS? There's a guy on Craig's List the will burn one for me for 175 and he sounds good. If I delete the smog stuff he can program all that stuff in his chips. I don't know if tbichips does that. TBI Chips offers a package of the chip, fpr #18# spring and a fuel pump for 340. That seems a little hi to me.

 

I feel you are better off investing that $$$ in burning equiptment. See craigmoates.

50/50 chance you wont be satisfied with the outcome of buying that chip.

If you do decide to buy it make certain he will do at least 20 re-burns for you when you send him log files.

 

Sry man I'm just not the guy that's going to advise mail tunes, I know it leaves much to be desired on both ends.

I'm sure you are aware of the Flash Mod for your ECM, just step up if your rig is worth it.