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So one day a few months ago my younger brother called me up saying he was ready to ditch the carb on his 67 firebird. Which is something I've suggested from the beginning.
He wants me to set up something and will trade me a very high end custom gaming computer for it. Well it happens that I'm a little short on cash at the time, and this is a kinda unusual application anyhow. So out to the garage I go looking at what I have that I may be able to adapt.
I have various single blade TB's but none really fit the bill, and then I see a 454TBI and an old Holley Pro-Jection 670 on the shelf. The light bulb comes on above my head, and I take them to work a few days later and start machining (I have a manual bridgeport and lathe at work to use).
What i come up with is a 2-piece 2"tall spacer plate that bolts to the single 4150 type carb flange on his Weiand 177 Blower. It has 12 Bosch designIII injectors coming in from the sides, into a little mini-plenum under the dual, 2"bore throttlebodies.
I trimmed the throttlebody units down quite a bit, and then made a plate that bolts on top that seals it up to some type of air cleaner(which we have not decided on yet).
The 6 injectors on the sides are spaced .800" apart and have to be flipped pver in alternating order in order for the electrical plugs to clear each other.
and BTW there is just enough room to squeeze 6 injectors in between the carb flange bolts, but not 7. So 12 injectors it is.
Why so many? why not. Actually I happen to have a quite a few 3800SC injectors which flow around 42lbs(IIRC) at 4bar. Should be plenty of fuel .
The 2" bore TBI's are rated at around 670CFM each. Thats with the injector pod on top which hurts flow a little. I dont think this thing will quite flow 1340CFM since there will be some losses inside the adaptor block, but surely it will flow at least 1200.
The engine is a 4bolt 454 with Brodix oval port Race Rite heads. Its got a Lunati solid flat tappet cam with around .620 lift and high 240 something duration at .050. Its ground on a 112 or 114 (I dont remember now). Basically its really mean on the street, and even with a 750 vacuum secondary on top of that little 177 blower, its extremely responsive (snappier than most hot small blocks I've dealt with). Of course the little blower runs out of breath a little early on this engine (would be better suited to a small block for sure). It makes around 8-9 PSI on this engine. More airflow on top should help a bit with the boost, and the EFI should help with consistency and drivability (which wasnt so great before).
Anyhow, we installed most of the hardware lest week, including the Fuel surge tank I machined out of a 4 1/2" billet. Its got an AEM-380 pump inside which I think should be fine for this engine.
In a week or two I'll be going back to install the wiring harness and computer. We are using a 730 with an EBL-P4. the car already has an AEM wideband I plan to connecto to, and I'm building an external inline injector driver to handle the extra current of 12 injectors (this unit could probably power 30 injectors if I wanted to).
And the bug catcher in the picture was for size comparison, Its also one of my next EFI conversion projects for a friend on his little drag truck with a 6-71 blown small block.
dual 2" bore TBI units on custom adaptor, with 12 injectors.
It does run. Its on my brothers car, and in his words "it feels like an extra hundred horsepower over the carb". And its not even tuned at all yet. I keep telling him "dont drive it till we can start tuning it", so far he hasnt hurt anything yet, and luckily its been parked lately while getting another rear end and some other stuff.
It is running a '730 computer with an EBL-P4, 12 x 3800sc injectors, Brodix Race Rite oval port heads, and a fairly mean Lunati solid flat tappet blower cam (thats not in the catalog).
The trans is a th400 from a motorhome that has the HD straight cut gears, and a 3000 stall converter. The car just got a fab9 rear with 3.73's and a full spool a couple weeks ago. As well as a set of Cal-Trac's and 4 wheel disk brakes.
Hasnt really been driven much with the injection, up and down a country road a few times. Maybe 5 miles on it so far. My bro isnt up to speed yet on EFI tuning and He lives 4 hours away, but he just dropped the car off at my place today so I can do some tuning on it and get it going. and when he gets back here on sunday to pick it up I'll try to give him a little class on basic EFI tuning, its really hard to do over the phone.
I can say that its VERY VERY snappy, but has some issues to take care of right now.
For one, the external injector drive I built to run 12 injectors was wired in wrong and wasnt firing. So over the phone I told him how to just bypass it and run the injectors directly off of the ECU's driver, so we disconnected the 4 outside corner injectors to bring it back to 8 so as not to overwork the driver. That may need to get fixed, but we can work with 8-injectors for now.
Also something I strongly suspected would happen did. The throttle needs a cable/cam setup to make it more progressive, with an estimated 1200-1300 CFM its very touchy coming off idle. Does a lot of short unintended burnouts, and thats not always good.
And I also plumbed the fuel pressure regulator to the manifold, but the injectors are above the rotors. I think I need to reference the regulator to the same pressure conditions the injector nozzles see. Right now it goes way to rich really quick and I think thats why. Also the computer is using manifold air temp and it should be using inlet air temp, I think. But the EBL lets you blend between inlet air temp and coolant temp for compensation, and I was reading someplace that just using coolant temp only was better. I may know this weekend.
Anyhow it works, just needs tuning and a few adjustments.
Last edited by The_Punisher454; 04-07-2017 at 12:51 AM.
I actually was just reading Simpson36's post the other day. I was looking at some ideas for installing bushings in the throttlebody's.
Also have seen simpsons posts at CNCzone too.
This setup is currently using just one IAC, and it seems to work just fine. In fact when we first got it fired up it wanted to idle real low (like 500-600) when cold and then end up idling around 1300-1500 when warmed up. turned out to be the IAC was wired backwards and was opening when it was supposed to be closing. Just swapped two wires and the IAC works fine now.
The car is at my house right now to be tuned. But honestly I haven't made much progress, I have only a few hours here and there, plus the car has a lot of things that need to be fixed or re-done first.
The franken-TBI unit seems to present some computer setup challenges, when used with a roots blower configuration like this. and of course the fact that that the cam is a solid flat tappet with 251/259 degrees@.050 makes idle tuning.....problematic.
I may have to try the N-Alpha mode on the EBL, at least for idle. I think that by 1400-1500 pure SD will be fine, but down low I'm anywhere from 75-90kpa, moving around quite a it, with the wideband showing big fluctuations as well.
I seem to have some vacuum leaks somewhere, and I'm hoping its not the throttle shafts. last week I had it idling down into the low 600 rpm range before the IAC counts bottomed out to 0. but this week the lowest I can get is about 950 or so with the IAC counts down to 0. That tells me its getting a bunch of air someplace.
I also think I need to install a higher temp thermostat. Its got a 180 now, and it seems to run better and better as it warms up the running quality starts improving a lot between 175 and 180 and gets even better a little over 180. I'm probably going to try a 195 this weekend and see if the afr's get more consistent, right now it burns the eyes too much even when its showing lean, I think a little higher temps may help.
anyhow, I have a lot of setup questions to post in the ebl thread. But I'll post back here when I have some more results soon.
I am running it all OL right now with the wideband. Right now somethings not right and I intend to find and fix it this weekend. I was doing VE learns and it was getting a bit better, then something went wrong and I kept on doing learns and it got really outta wack. Plus I made some changes that probably invalidated the initial tuning anyhow, so I've been starting over.
Yes I have a 2 bar map sensor on it already.
Untill I get the idle and bottom end a bit better this thing isnt going back out on the road.
I can do a lot of stationary tuning in gear up too around 3000rpm or so, its got a converter thats stalls probably around 3500-4000.
11-20-2016, 02:33 AM
