12.48 @ 109.82 w/ no power adders!!!

Last best run was a 12.49 @ 105.

The Injection Volume was TOO RICH, just leaning out the MAP from 2500 RPM up gained almost 5 MPH.

The car pulled strong with no signs of detonation so I could try to pull a little more fuel out until the car slows down or it starts to break up, That should dial in the WOT performance.

Who says TBI can't be fast!?

 

Can you post your setup?

 

Wow, your really cooking. What are you running?

 

That is really fast- congrats!
Where did you run? Union Grove or Rt 66 or ?

Yes, also- let us know the setup!

S-D

 

"Often imitated Never Duplicated"...

I can't give away all my trade secrets

Seriously I will be very general to describe in great detail is too time consuming.

350 SBC
Cast Iron Heads 10.5:1 CR
Roller Cam w/ 110 LSA
Holley Projection 4Di

465 HP 472 #/ft

 

Hey, thats cheating! . J/K. That 4 bbl tbi is a really nice piece. I want to get one of those but theyre kinda pricey.

 

The nice thing is that the 4bbl TBi will flow plenty of fuel... more than the stock one can ever dream of.

I was lusting after a 4Di system all thru college and for years after. I found mine on eBay back in 2000... They are out there. Funny thing is the same year I bought mine, Holley came out with the Commander 950, go figure...

I was thinking about upgrading to the Commander 950. Simply a matter of replacing the ECU and engine harness about $500 to upgrade.

The Commnader 950 ECU is neat you can use it to drive 4 high impedance injectors or 8 low impedance. You could easily switch to MPFI without having to change ECUs.

For now my "obsolete" 4Di works just fine.

 

If its one of the newer ones it came with 4 60 pph delphi injectors. More then a pair of standard '90's or whatever flow rate they really are.

 

you could get the 4Di with injectors up ot 85pphx4

i do know that it will not suppor the HP a blown 468 can produce. It was topped out by about 550hp.

 

If their the newer ones then that rating was at 21 PSI. Holley tech and delphi both show them to be 60 some odd pph at their rated pressure of 10 psi since theyre standard tbi injectors. Jsut a rating, though. More pressure will cause them to flow more just like any other injector.

 

can it be mated to a GM ECU? it was suggested GM better than Holley? if so, which ECU and what does it take to drive 4 injectors? how does one get it (GM ECU) modified to do so. i cannot do iy myself (komputer nitwit).

 

This seems to be the question that no one on this board can or is willing to answer...

Holley figured out how to fire 4 injectors. Matter of fact the Commander 950 ECU can be set-up to fire 4 or 8 injectors.
You could switch from TBI to MPFI or vice versa. So it can't be that difficult.

I think too many of the "experts" on here are hung-up on the stock ECMs and the "big block TBIs" I was branded a heretic several years ago for making the claim that on a performance application the stock equipment is "junk". Good to see that after 4 years Pablo is beginning to figure it out.

 

There is at least one member doing this. He build his own second injector driver board to do it.

 

by coincidence i had a "company" conputer tech in office yesterday reconfiguring some of my office equiptment. i ran this question past him. he said same thing(basically) but was over my head. felt easily doable by adding another board. some day i will run the Holley 700 or 900 but heard the Holley ECU is not nearly as good as the GM stuff out there. i would hate to specd that kind of $$ and end up with an ECU that was inferior. maybe Holley has better computer control in 2005?

 

Who have you heard that from, and have they actualy used the C950? the C950 has some neat things that it CAN do, including up to 3bar MAP support, Alpha-N mode, and WB support.

 

well now wait a second, i havent run TBI in atleast 3 years, the first I was "busy" and the second, i was out of the country, and the third has been carb.

Secondly, I think the GMECM works just fine, the limation that I bring up is the firing strategy of the TBI ecm which requires that your injector sizing formula be much more generous than it would with other FI setups. This means that even with the largest injectors you are going to have to increase the fuel pressure a bit to get what you want. No big deal though. Sure, youll top out eventually but, then you can, like you did, go to the 4 barrel setup.

I think you guys have missed alot of posts or something, the 4 injector thing was hashed out too allready. Yellow73BB on the diy prom board made injector drivers to run the extra two injectors and i think even sold them for awhile.


The only reason people dont go fast with tbi is because they dont tune it. I personally believe that without a wideband tuning is impossible. The fuel curve is just too finicky to get right otherwise. ITs finicky enough for me even with the wide band but i think ive got it nailed now

 

honestly i dont know. just reading this board past year and a half i thought a member(s) found the Holley ECU lacking the functionality of the GM units. again this may have been earlier units. also i thought it was said it was a struggle getting the car(s) dialed in such that they run well. again pointing the finger at the Holley ECU not the Holley TB unit. please correct me if you feel the Holley TBI is a great package. as i stated someday i will run the Holley 4 barrel.

 

oops that was for Dew.

 

I am sure it would depend on what GMECM you are comparing it to.

but here is my limited experiance with the C950 vs GM.

good friend, and memeber of this board (twilightoptics) (my tuning buddy, we help each other tune) build a killer motor.

355, 210cc heads, HSR, Solid Cam over 240* intake duration, 110 LSA, 565 lift. 3000 stall.

he initial started with a 1987 GM MAF ECM, the car NEVER ran well, after hundereds of chips. it wouldn't hold an idle, etc.

Installed C950 when we could not fix it, we tried everything, we replaced everything. With the basemap we downloaded from the holley website, that was for a similar combo, it idled and drove descently with that basemap, after some small changes it drives wonderfully. It took maybe a few hours to tune, being able to tune of the fly, and being SD, it worked great. Also the simplicity of only have ONE fuel map, and ONE spark map are great. We didn't have to try to figure out how 6 spark tables interacted, or 4 fuel tables, etc.

 

i guess there is something to be said about simplicity. i guess that would be best for me and my limited skills. i am overwhelmed by all the tunable parameters i have seen. i believe it is best tunercat did not include all of them. they have added a couple per my request.

 

The major differences are that the GM ECM;

Activates torque converter lock-up. (TCC)
Adjusts idle speed when A/C is turned on.
Has limited "learning capabilities"


I have a non A/C car.

I have a "dumb" converter (non lockup) which means a few more rpms at cruising speed. I could possibly activate the TCC solenoid with a toggle switch. TCI now makes a 3000 RPM stall with lock-up function