GhoSSt

iTrader: (1)

Hey guys I have a 400 here fresh from the machine shop with a custom comp cam, Dart
Iron Eagle heads (215cc intake, 64cc chamber), and I'm trying desperatly to figure out what to do about fuel delivery.

Its going into a 1993 Caprice with TBI. This car currently has the L05 with the 9C1 (police package). So I have the 65lb injectors, etc..

Do you guys think that this TBI setup will support the new engine to its potential? I'm
only spinning it up to about 5700rpm and
the TBI system is BONE STOCK, none of the
Ultimate TBI stuff yet, other than to throw
away the thermac riser that was included on the B-body. Any thoughts?

(BTW) I know I'll need a custom chip, probably from Howell, since they're REALLY into TBI. But what about the TB itself? Will it hold up or do I need to go to the Holley one? My air cleaner has 2 studs, one on each side, not the central stud like you F-body guys have, so I may have fitment issues with the 670 Holley.
------------------
Kelly 'GhoSSt' Rosato
1996 Impala SS, 383 LT4 (14.65 up here, 13.24 lower)
1984 Firebird, +.060 350 (Vortech Heads, HOT Cam, and schtuff)
1993 Caprice, 5.7 TBI (stock . . . FOR NOW)

"And if you wrong us, shall we not revenge? Revenge. The villany you
teach me, I will execute, and it shall go hard but I will better the
instruction."

Shylock in Act III, Scene I of 'Merchant of Venice' by William Shakespeare

[This message has been edited by GhoSSt (edited November 27, 2000).]

Tas

go for dual TBI. I have the link on my EFI page.

------------------
-Tas
'89 Formula WS-6
[soon to be Performace Red =) ]

305, TBI, auto, 14x3 chrome flat based open element with K&N, functional Formula hood, cross-flow Flowmaster, '99z28 rear pipes and tips....

Super GRK_Taz World
EFI & Intake Options
AOL IM: superGRtaz
ICQ 82881207

GhoSSt

iTrader: (1)

Thanks, but I'd rather not rewire a bunch of stuff. My question is whether or not the stock TBI can support the engine in question.

Kelly 'GhoSSt' Rosato

Mark305TBI

I'd say that you certainly need AT LEAST a 2" throttle body. The stock TBI unit only flows around 400cfm, not nearly enough for a 400cid engine. I think the dual TBI system would be nice, 800cfm (with the stock TBI) or 1340cfm (with the 2" TBI) would be plenty of air for a healthy 400, but you dont wanna re-wire anything (it's OK, I understand).

-Mark W.
'88 SC Camaro w/ 305 TBI

Brent

iTrader: (1)

I don't know how much HP your 400 will make but I would be concerned about fueling it.

The stock fuel pump may not have enough capacity. <CR>
The other issue is the injector flow rates.

2 inj flowing 65lbs/hr are good for approx 260HP at .5 BSFC.

2 inj flowing 90lbs/hr are good for approx 360HP at .5 BSFC.

You might consider a 4 bbl TBI and just run the front 2 injectors (large units). There are issues with running 4 injs off the factory ECM I believe. I haven't done more that give it a thought so I can't tell you if it'll work easily.

NJ SPEEDER

brent is right about the injector sizing. you prolly need to step up to bigger injectors to feed the beast. you may want to try fixing up the stock tb first if you wanna try to save some $$$$$. once you plain the top smooth and double the gaskets to raise the injector tower you can get it to flow almost as good as good as any of the ones with bigger bores.
i haven't got any proof yet, but i believe that a properly prepped stocker can support 325 to 350hp.

lata
tim

------------------
91 Camaro RS-LO3,Auto.
14.301 @ 94.39mph
The car is going street strip for next season. 13's here i come!!!!!
Edlebrock TES Headers, Cat Eliminator Pipe, Borla Adjustable Cat Back,Marche Pulleys, HyperTech Chip,Transgo Shift Kit,B&M Convertor(2000stall),Steve Spohn Rear Rig( all rod ends), Poly Front Bushings,Ported TB, 350 Injectors, Edlebrock Performer TBI Intake, Performer Heads, 1.6 Roller Tipped Rockers

Dan W

Hello again Kelly

A 2bbl TBI 406, now were talking!

First things first, what are the air and fuel demands of the motor? To figure this out I need to estimate HP and VE. I'll guess at 400 corrected crank HP and 90% VE. Sound Good?

Airflow requirements:
Volume in ci / 2 * rpm / 1728 * %VE = airflow
A 406 running at 90% VE and 5700 rpm will require at least 600cfm airflow... a motor with a dual plane intake will like 10-20% more than this.

Will your stock TBI work for the task? What is the bore diameter? If its not the 2" bore unit, and I don't think it is, I'd say no, its not up to the airflow demand. The 670 btw is a 2" bore TBI unit.

So your tbi is probably up to the fuel demand but not the airflow demand. Also consider a GM 2" 2bbl from a big block truck... I've priced these through Colorado Springs Junk yards (with national parts locator) and have found them about the same price as new Holley units. The fuel pressure regulator on them can be made adjustable. Their injectors are larger than yours but I'm not sure exactly what they are w/o doing some research.

Here is a link to show how to figure the fuel requirements for your motor: http://prestage.com/carmath/calc_fuel.asp
This formula does not adjust for duty cycle.
I think you'll find that 130# of fuel is a bit small for that motor. But...

Here is a formula to calculate the fuel pressure required to obtain a desired flow rate:
New Pressure = (original pressure * desired flow * desired flow)
---------------------------------------------------
(original flow * original flow)

Pablo, help me out here. The stock injectors are rated at 9 or 11 psi, I keep forgetting. In any event, its been reported that the GM style injectors can be run at very high fuel pressures... I've heard of over 20 psi and I was talking about someone with Pablo who had tested them to over 30 psi.

Holley rates their injectors at 15 psi.
The Holley 2 and 4bbl TBI units use a dodge style injector that is commonly believed to exhibit lock problems above 18 psi.
Holley also sells GM style injectors (replacements for their 1bbl kits)
pn 522-40 (Holley 1998 catalog) is a gm style 90# injector.

As far as injectors go... a pair of GM 65# injectors will flow more if you raise your fuel pressure. 93# will support 340 hp (15% altitude correction) at 90% duty cycle and .5 bsfc. 18 - 19 psi will get you there.

The Holley TBI units come with an adjustable regulator. You can make simple adaptations to run your stock injector pod on a Holley 670... this is the way I would probably go in the absence of a GM 2" bore unit.

Of course there is no real way to get your chip down perfectly w/o some trial and error… unless your chip tuner has spent countless hours of development time on your exact combo. After all, we can only guesstimate %VE, HP, timing requirement, manifold vacuum at Idle, etc. in the absence of some real dyno tuning.

When it comes time to do the chip thing, drop me a line… I'm just down the street and I may be of use in a number of ways. For example, I have a chip burner, some spare chips and an EPROM eraser… Troy could burn changes and e-mail them… turn around could be an hour or so instead of a week waiting for the mail.


1988 T/A,
9" Ford, 3.50 gears, Auburn posi, 700r4 -w- 2100 converter
350 .060 over with forged 1 pc rms crank, and forged TRW pistons, 9.5:1 cr
Factory GM heads Pocket ported, 2.02/1.60 valves, back cut
Comp Cams roller 219/227, .479/.480, 112 LSA
Holley 700cfm 4bbl on TBI truck 7747 computer and chip by Howell-EFI
Edelbrock Performer EGR intake, Edelbrock TES and 3" cat


[This message has been edited by Dan W (edited November 27, 2000).]

91Bird305

Save yourself the trouble, go carb.

------------------
Eric Natzke
91 Firebird 305 TBI (ZZ5 summer of "01")
ASCD Ram Air Hood-3" custom exaust-Flowmaster 80 Series-No Cat-Edelbrock TES Headers (coated)-March Pulleys-TBI Spacer-K&N Open ELement-TransGo Shift Kit-B&M Supercooler 28,000 GVW-Hypertech Thermomaster-160 Stat-3:42 GM Gears-Auburn Posi Unit-Edlebrock Strut Tower Brace-MSD Superconducters-MSD Cap & Rotor-MSD Blaster Coil-Rapidfire Plugs-265/50/R15 Tires-Emmison's all Gone
http://members.aol.com/j007golden/91firebird.html

Pablo

iTrader: (1)

I think the stock injectors are rated at 10 psi

I went through some trouble when i first started trying to figure out the fuel side of it but i think i now have a pretty solid setup and that is using an external NOS regulator at around 19-20 psi on my stock injectors

Ive run up to 50 psi on the stock injectors without locking them up. This of course will take a different pump than stock but you can support alot of hp like this especially with the BBC injectors

you will DEFINATELY need a BBC throttle body, forget about the stock unit, my 305 was choked by it on a single plane (i was seeing around 2 inches of vacuum at 5500 rpm)

i put a holley 670 cfm tbi unit on there and first off i have no vacuum at wot and after some tuning there was a substantial performance difference

and dont forget the single plane

GhoSSt

iTrader: (1)

Originally posted by Dan W:
>
> Hello again Kelly

Hey Dan. Wassup?

> When it comes time to do the chip thing,
> drop me a line… I'm just down the street
> and I may be of use in a number of ways.
> For example, I have a chip burner, some
> spare chips and an EPROM eraser… Troy
> could burn changes and e-mail them… turn
> around could be an hour or so instead of a
> week waiting for the mail.

**** man, I'll buy you lunch just for offering. But I think I may turn to the dark side. Howell and I have done lot of work in the past and he's got me talked into a type of MPI conversion based losely on what Edelbrock sells, with the custom chip for a tad over 750.00. I really can't say no to it, 4 wires to splice into my harness, drop the tank and plug in my LT1 sender and fuel pump, then fab some lines and plug in a prom and wham, 3 or four hour multiport conversion on thin dime. But hey, if you're up for it, me and my partners will probably be doing it down at his house in Castle Rock. We can all have beer and a good old time.

LMK.



------------------
Kelly 'GhoSSt' Rosato
1996 Impala SS, 383 LT4 (14.65 up here, 13.24 lower)
1984 Firebird, +.060 350 (Vortech Heads, HOT Cam, and schtuff)
1993 Caprice, 5.7 TBI (stock . . . FOR NOW)

"And if you wrong us, shall we not revenge? Revenge. The villany you
teach me, I will execute, and it shall go hard but I will better the
instruction."

Shylock in Act III, Scene I of 'Merchant of Venice' by William Shakespeare

Dan W

"But hey, if you're up for it, me and my partners will probably be doing it down at his house in Castle Rock. We can all have beer and a good old time."


Sounds good, e-mail me when youre up for it.

91Bird305

E-mail Shane Buss, it doesn't look like he is going to be stopping by anytime soon. His e-mail is

shaneb@ev1.net

Also try e-mail this guys, Coolfb@aol.com

Josh is doing the same swap as u are. He is dropping in a 400 bored over .060 I know he has been doing research on an injection system for it. Hope this helps.

------------------
Eric Natzke
91 Firebird 305 TBI (ZZ5 summer of "01")
ASCD Ram Air Hood-3" custom exaust-Flowmaster 80 Series-No Cat-Edelbrock TES Headers (coated)-March Pulleys-TBI Spacer-K&N Open ELement-TransGo Shift Kit-B&M Supercooler 28,000 GVW-Hypertech Thermomaster-160 Stat-3:42 GM Gears-Auburn Posi Unit-Edlebrock Strut Tower Brace-MSD Superconducters-MSD Cap & Rotor-MSD Blaster Coil-Rapidfire Plugs-265/50/R15 Tires-Emmison's all Gone
http://members.aol.com/j007golden/91firebird.html

Grumpy

To reliably support 325 with my 355 I had to go with 2" bores, and the early BBC injectors. My car was light, and needed ALOT of AE to get her going. Good running 400, I'd go with the early BBC TB and tune from there.
Unless, all you want is all the grunt in the world at low rpm.
Might also run out of manifold.
Single planes with TBI are fun in my book.