dimented24x7

iTrader: (2)

My feelings as well... We know that the holley and the larger 2.2 in TBI, which is as large as a set of secondaries from a q-jet, but without all the crap in the way, can at least support some flow. Theres also more to airflow then jsut the numbers. Theres the dynamic aspects of how the tbi and the intake will react. If we notice that its pulling some vacuum at times, we can always try different intake and spacer combos, but if we notice that we just nuked several thousand dollars of stuff because we didnt have enough fuel, then game over...

Thats why I personally feel that fuel should be the primary consideration as being short on airflow wont have any other effect then that of running at altitude.

dimented24x7

iTrader: (2)

Wow, do they have any flow numbers at those pressures? Id also imagine that using an external FRP and blocking the stock one off wouldnt be a bad idea. The diaphram there looks kinda flimsy.

Pablo

iTrader: (1)

I hate to sound negative but everything in this thread has been literally beaten to death numerous times, probably before most of you got to this board we had debates on these very things.

The data on injectors being good up to extreme pressures has been around on this board since 1999, i posted probably a few hundred times talking about myself running 50 psi regularly and boosted TBIs shooting up the FP to rediculous levels with the superchargers FMU.. this is on prefabbed kits specifically for TBI cars.


The airflow thing has been hashed out numerous times too, I thought a year ago we had settled this especially with the numerous data sources posted on the 1.5" hg flow of Tbi throttle bodies.


Bottom line, none of this matters for anyone on the TBI board anyways, you can talk about peoples engines falling flat on their face at X rpm but I have been here since this board began and none of those people (and I have known quite a few personally from chatting on IM or ICQ).. NONE of them ever tuned their setup correctly if at all.



That means chip burning period and I now believe that a wide band o2 setup is nearly a must.

I have spent 2 years away from TBI and have wrung out the times in my sig from a 305 with an edelbrock carb. Today I finally got the tbi working again and saw what the real problem is with TBI

Tuning! it wont be anywhere near right unless you tune the thing and tune it correctly which became painfully apparent to me when I saw that the chip i used to drive around on back in the day was actually so far off it was scary (Observations made via WB O2)

Pablo

iTrader: (1)

btw 50 psi was with the stock diaphragm in place

dimented24x7

iTrader: (2)

I knew it was inevatible that the same stuff would end up being beaten to death again after the thread got underway... but I had to start somewhere.

Hopefully the next topics should be a little less threadbare for the more senior members here.

BronYrAur

iTrader: (1)

I'd also worry about the diaphragm up that high. Like Pablo said the results I'm referencing were from years ago, maybe 2000 or 2001. They didn't have any flow numbers, just that they worked. I believe he also verified that the 90pph injectors were the biggest ones but it was still unknown about the fabled bigger injectors used overseas, (australia maybe?). He didn't know anything on those.

va454ss

iTrader: (1)

Supposedly, there were larger GM injectors for the Brazilian market. I believe they were used with alcohol as a fuel. No one has been able to confirm this.

Maybe we can get someone to scour the boneyards in Brazil for a TBI BBC.

Walt Sherwin did indeed flow test the GM 75 lb BBC injectors to 70 psi. This was done on a flow bench.

I currently don't have any pictures available, but I'll give some details of mods and experiences.

My TB has the 2.2" bores. I have also smoothed the entry to the bores. I have totally removed the center leg of the injector pod. My wiring exits the rear of the TB vs the front for stock.

I don't have an air cleaner stud in the front of the TB. I use two studs that come off of the injector pod at the rear of the TB. (The 92 and 93 SS454 pickups came this way, but not sure about the 91.)

Its almost comical whenever I see pics of a stock TBI system. I do a double take for a second thinking "What kind of setup is that?"

I'm also using an external fpr.

I've also fabricated injector covers from another injector pod I hacked up. The wiring goes vertically off of the injectors out thru the top of the covers. Modifying the connectors/wiring was a pain, but at least it looks cool.

TBI injectors are capable of fairly high fuel pressures. The issue is tuning at idle with high pressure. This is where a vac ref fpr and calibration that takes into consideration the varying flow rates of vac referencing.

va454ss

iTrader: (1)

Wow.

No replies to my post at all.

Not sure what to make of that.

BronYrAur

iTrader: (1)

Yeah, this post was going crazy for a few days now it just suddenly died??

VA, That sounds like you really setup that TBI nice with the 2.2" bores and all the modifications. That sounds like the ultimate flowing throttle body one could achieve out of the casting.

dimented24x7

iTrader: (2)

One thing I would like to see is flow test results on the TBI injectors at high pressures. If I ever get around to it Id like to flow test them and see jsut how high the flowrate can get.

dimented24x7

iTrader: (2)

I guess Ill be unhooking this thread soon... Stay tuned for the next topic.

iroczracer07

iTrader: (2)

I realize this thread is seriously out of date, but I think the best set of heads to use would currently be the A.F.R. 180 competition.

thecaminator

I'll just tell everyone what I did to my wife's Camaro and y'all can do what you want with it. We pulled the old L03 and found an 85 TPI motor at a friends house. We slapped 1.6 rockers on it and modified the Edelbrock TBI intake to mount to the old style heads. I'll tell you what, that thing lopes at idle with plenty of vaccum. With all emissions hooked up and open element filter and a little timing and idle adjustment, I ran 8.89 at Motor Mile Dragway (1/8).

91rscammie

iTrader: (2)

Okay I know this is old and will probably get unhooked but I was wondering if anyone has done or thought of doing a dual TBI a while back I seen a GM based boat motor that had a dual TBI set up on it. Not the crossflow it had the same TBIs as our cars have. It being mad by GM seems like it would be easy to modify one of our cars with one and easy to tune. I heard that they make a kit for a supercharged verson also that will make 700+hp. I seen one of these motors with the dual setup Minus blower in an older camaro on two guys garage Probably 10 years ago. I was wondering what could be had with one of these kits minus the blower on a descently built motor. Has anyone ever seen one or used one and at what cost can u get one at? I believe they came on the GM based Mercruiser engine.

Ronny

iTrader: (1)

Feast your eyes on this...https://www.thirdgen.org/forums/tbi/...tbis-dual.html

here is extensive discussion...https://www.thirdgen.org/forums/tbi/...etup-idea.html

keep in mind one would need to reduce fuel pressure considerably to prevent overly rich idle. VAFPR I use can pull 19.5 lbs down to about 11.5 last time I looked.

91rscammie

iTrader: (2)

Nice, but I was refering to two, two barrels on a dual quad intake. Iknow Ive seen this done twice befor and kits with superchargers but cant seem to find it.

Jason Sharpless

what stock heads would be better swap for my 305? and also is the high energy cam a decent up grade?

Ronny

iTrader: (1)

see stickies above...