TBIThrottle Body Injection discussion and questions. L03/CFI tech and other performance enhancements.
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My brother finally went to the track and I finally got times from the 312 TBI that I built many moons ago. My brother killed his L05 in his 1990 RS and was out an engine. I've been tripping over the 312 in my garage, so we put my 312 into his RS.
His RS is a stipped down model from the factory, very few options. Manual locks, manual windows, A/C, and thats about it. The stock 350 TBI truck engine blew up the original 7.5" 2.73 geared 10 bolt shortly after swapping the 350 in and we put in a 3.23 geared 9-bolt from a GTA. The transmission is still a stockish rebuilt 4L60E, but has some goodies to it. Superior shift correction kit, Corvette servo, TV boost valve, etc. It has had a Walbro fuel pump and it had previously been converted to the TBI PCM from a 1995 C1500 Truck.
We put my 312 into it with a 2,800 rpm lockup torque converter about 4 weeks ago. Tuning has gone well and the car runs awesome. The newer PCM and 4L60E offer great driveability for a TBI car. Once the tuning got close, it has averaged 20 mpg over the past two weeks and 1,500 miles.
The 312 is a bored out 305, .040" over to be exact, 10.7:1 compression, ported 463 casting ZZ4 heads, Comp Extreme EFI 280 Roller cam, 1 3/4" primary headers.
Crank = Stock GM Forged Steel (3941188), Lightened, Smoothed, Knive Edged, etc for less windage, balanced with the entire rotating assembly
Bearings = Federal Mogul Speed Pro Coated
Rods = X casting rods, Parting lines ground down, Lightened, Balanced, Shot Peened, Weights Matched, ARP Wave Loc 3/8 Rod Bolts, Reconditioned
Pistons = Stock L69 Hypereutetic Replacements, Flattops with 4 valve reliefs, -6 cc, 0.00" in the hole
Rings - Total Seal Gapless rings
Compression = 10.7:1 with 54cc heads, Zero Decked block, .038" compressed head gasket.
Heads - Ported 2004 ZZ4 castings ("463"s), cleaned up in my garage, final "MAX EFFORT" port work performed by my buddy in his machine shop, .100" longer valves than stock (1.94/1.55 Under Cut Stems, Swirl polished), 5 angle valve job, Forget the exact spring but they are meant for the cam and .100" longer than stock valves, .600 lift compatible. I had to use longer than stock push rods as well. Machined heads for Comp Cams guide plates after opening up pushrod holes in heads. Gasket matched to a Felpro 1206 (1.34" x 2.21")
Head flow @ 28 in/h20 with a 3.75" bore simulator (engine has 3.776" bore).
Lift------Intake---Exhaust
.100------57-------57
.200------123------118
.300------177------162
.400------223------183
.500------229------188
.600------238------193
Intake Manifold = Holley Projection TBI for "OLD" style heads with the same bolt angle. This intake is a dual plane, high rise, with 2" bores. Gasket matched to the Felpro 1206 intake gasket
TBI = TBI unit off of a Heavy Duty 7.0 liter TBI truck, 68# injectors at 32 PSI, 2" bores, thinned throttle shafts, radiused the entrance to the bores, sitting on a 1" tall open center TBI spacer, 720 CFM @ 3.00 in/hg
Headers/Exhaust = Hooker Super Comp 1 3/4" x 3.5" meant for a mid 70s Camaro with a 350. 3" duals with X-pipe (not used on dyno)
Ignition = Stock GM HEI EST small cap distributer (computer controlled) with MSD coil, MSD Module, Moroso Ultra 40 wires, AC Delco Rapidfires @ .045"
Oil System = Moroso Blue Printed Oil Pump w/ Pickup, Moroso Steel Shaft, Moroso 5 quart pan, Moroso Oil Control Kit, Mobil 1 5w20, 70 PSI Z/28 spring
Crankcase Evac = LT1 style Electric AIR pump pulling a crankcase vacuum of about 6 in/hg.
ECM = RBob's EBL with lots of tuning. 34* total advance @ 2,800 rpm.
Dyno Numbers (all rounded to the nearest whole number for simplicity)
The TBI unit was actually a HD C60 series Big Block Truck unit. It has 2" bores with the odd Delphi style injectors in it. 68# @ 32 psi was used to get in the fuel. RBob's EBL was in control of both the fuel and timing.
The car was promptly booted off the track for lack of a rollbar and the proper equipment.
The car was run on the track with Hooker 2460s, dual 3" into single 3.5" exhaust, 2,800 rpm converter, and Goodyear Potenza 245/50/R16s on stock 16" aluminum rims, car weighed in at 2,700 lbs without driver. Brother weighs 140 lbs, upshifts were computer controlled @ 6,400 rpm, launching at anything above idle on the street blows the tires away.
The car is fairly quiet, smooth, and FAST
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Last edited by Fast355; 03-25-2007 at 11:50 PM.
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That car is lighter than light. That must be factored into the equation. Good times though.
Im surprised it weighed that little (relatively speaking...) I wouldve expected it to be about 300-400 lbs heavier. even with the extra weight, it would still be good for low 12's.
Yea, like geez, 11seconds on a 305? That's pretty much uncharted territory right there.
A nice big cam, but the heads aren't record setting or anything. Nothing unbelieveable there, vortec level sorta thing.
How's the torque with that big cam? Dyno shows it to be pretty healthy, above 300 at 2400RPM...Quite driveable?
Why use the .1" longer valves?
I wonder what factors come into play very much in that combo. ie, if you bolted on a performer RPM q-jet intake and a non-cc q-jet - what HP level would it be at? Or a square bore RPM with a holley 750, where would it be?
I'm just curious if the TBI setup would be higher or lower.
Excellant results. Those are very good numbers. That car must be stripped to the hilt for 2800 pounds. Looks to me you could be going faster with a higher shift point. You are still making 419 horsepower at 6600rpm.
2,840 lbs with driver was NOT easy. The car was pretty stripped already and we tossed most of the heavier parts. For instance the car has been converted to manual steering and manual brakes. The emissions equipement was tossed. The car was without interior at the track, driver-seat only. The heads are aluminum instead of cast-iron, the water pump is aluminum, GM Vortec light-weight starter, A/C delete, etc.
As the old adage embellishes, "light makes might". You have a much faster car than those numbers would honestly imply. Nice to see an 'anemic' 305, with a 'laughed at' TBI system, in C6-ZO6 territory. Congratulations, Fast....
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... wait til Prevost see's this lol!
__________________ 2009 Corvette ZO6: Black w/Black Leather, F1R Coming.... 1990 Trans Am GTA: Black w/Black Leather, 305 w/T-76, 200R4.... 1989 Trans Am TTA: White w/Tan Leather, 3.8 SFI Turbo, 200R4....
Last edited by Street Lethal; 03-26-2007 at 07:26 PM.
Reason: Automerged Doublepost
Hmmmm. I'm interested in the problem you are having with the 4L60E at 6400rpm. I have already purchased a 4L60E for my car. I plan on installing it later in the year after my intake mod. With my dyno graph it appears I will be shifting around the 6400rpm mark if not a tad higher. Any information will be greatly appreciated as to special parts.
Bravo!! Bravo!! Those are damn good numbers, even in a 3800 pound car that would be easily into the 12's.
I think this proves without a doubt that there is enough fuel and air via TBI to make 425 hp no problem, this was with 68 lb injectors!!!! imagine what you could make with a set of 90 lb'ers.
This should give the naysayers something to chew on for a while......I see Dyno Don has already checked in with his first cop out.
Good job! The heads don't look like anything particularly wild, cam's a little on the large side as others have said, but looks like it works! Congrats
I think this proves without a doubt that there is enough fuel and air via TBI to make 425 hp no problem, this was with 68 lb injectors!!!! imagine what you could make with a set of 90 lb'ers.
If his air/fuel ratio is already perfect, then larger injectors will not make more power. Only if the engine is lean and needs larger injectors, will they make more power.
Quote:
10.7:1 compression is kinda tough to do on pump gas isnt it?
Only if you intend to race it on the street. I run 89 octane with about 10.5:1, and it only pings if I stand on it. At the track, I swap to 100 octane and increase the timing 6 degrees.
Is the Holley unit 2 injectors or 4? What's most impressive is getting a thirdgen down to 2700 lbs. You'll have to share those secrets.
Good lord Kevin, I'm not that stupid. I was mearly commenting that we have ability to support more power with bigger injectors. The throttle body is a 2-bore unit.
10.7:1 compression is kinda tough to do on pump gas isnt it?
Not really, with that much cam, aluminum heads and a timing curve to match.
It does make more power running E85 and a suitable timing curve though.
As far as getting the car that light, just start stripping things from it, take it down to the bare minimum, the body, a seat, and the glass. Ditch the boat anchor exhaust manifolds, the cat, the heavy stock muffler and exhaust. Power steering pump and hoses, power brake booster, carpet, sound deadener, interior door panels, etc.
Don't bet on it...remember only a select few could ever accomplish that.
One thing to remember about fuel injection is that unlike a carb, you cant broad brush the needed changes to the tune. With EFI, you have to tune every little detail due to the fact that there are so many individual operating parameters in the computer. Its much harder to tune with any EFI system. Also, the stock ECMs where junk, and have no place on any car being used in this day and age. it can hardly meter the fuel properly in stock form. I was able to get around it all with a $50 dollar PCM, a $25 dollar LS1 MAF, and some wire from radioshack. Not a terribly hard mod. Theres also EBL, which requires no modding at all. Cars go from running like crap to running like a champ. Easily proves that the engine doesnt really care whats on top of it. it just needs the right ammount of fuel and spark.
Actually, the EBL ran the engine on the dyno, but a 1995 TBI G20 Van PCM (16197427) was running both the engine and the 4L60E in the car and at the track.
The TBI unit is actually a HD C60 series Big Block Truck unit. It has 2" bores with the odd Delphi style injectors in it. 68# @ 32 psi was used to get in the fuel. RBob's EBL was in control of both the fuel and timing on the dyno and the TBI PCM at the track.
Here is a screenshot of the EBL display with it comfortably idling at 700 rpm with 11 in/hg of vacuum present.
One thing to remember about fuel injection is that unlike a carb, you cant broad brush the needed changes to the tune. With EFI, you have to tune every little detail due to the fact that there are so many individual operating parameters in the computer. Its much harder to tune with any EFI system. Also, the stock ECMs where junk, and have no place on any car being used in this day and age. it can hardly meter the fuel properly in stock form. I was able to get around it all with a $50 dollar PCM, a $25 dollar LS1 MAF, and some wire from radioshack. Not a terribly hard mod. Theres also EBL, which requires no modding at all. Cars go from running like crap to running like a champ. Easily proves that the engine doesnt really care whats on top of it. it just needs the right ammount of fuel and spark.
I disagree a little bit, I think the stock computer is definitely adequate. My car idles fine, great throttle response and makes some power. My combo isn't as wild as Fast's or even yours, but at my power level (216/260+ to the wheels) I have no desire to upgrade to a more versatile ECM. Maybe all this will change after messing with Nic's (snuflupgus) car though.
__________________ Purple Haze 92' RS LO3 5-speed
Ported TBI, 55pph injectors, Edelbrock Intake, LT1 Cam, SLP Headers with elec. cutout and Hooker Catback, Full MSD Ignition, Nitto Drag Radials, LS1 D/S, 3.42 posi disc rear, Spohn LCA's and relocators, WBO2 & Prominator, 36/24 mm sway bars, 4" Cowl, Nitrous, 17x9.5/11" Gunmetal ZR1 wheels, Koni Yellows, C6 brakes, J&M Camber/Caster plates, WS6 springs. Up next: PHR, Roll bar, GC Weight jackers
idles at 65 kPA yet closed loop at idle? how is idle quality?
What you hear in the video is what it sounds like. The engine idles very well, no hint of stalling or anything. Just runs very lopey.
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Quote:
Originally Posted by TonyC
I disagree a little bit, I think the stock computer is definitely adequate. My car idles fine, great throttle response and makes some power. My combo isn't as wild as Fast's or even yours, but at my power level (216/260+ to the wheels) I have no desire to upgrade to a more versatile ECM. Maybe all this will change after messing with Nic's (snuflupgus) car though.
I disagree with your statement, once you go to the TBI PCM or EBL you will change your mind. Both offer a huge driveability improvement, especially when used with a functioning Manifold Air Temperature sensor. The more versitile PCM and EBL off improved throttle response, quicker ETs, better top-end HP, more flexibility, and improved fuel mileage.
Here are the main highlights as to why the TBI PCM is better (EBL has its own thread detailing its advantages)
Much expanded Timing and VE tables to 6,400 for more accurate fueling
Open and Closed throttle Timing tables
Cranking Fuel is Pulsewidth based and is reduced via distributer reference pulses, giving a fast, easy startup.
Manifold Air Temp (IAT) compensation for fueling
AE/DE/DFCO is much more controllable
Controls EGR much better
Smart PE mode (Above a certain TPS% the PCM will return to open loop, but not enter PE, saves gas in high loading and lets the engine run smoother under load)
A/C Compressor controls (add a relay and it will cut the A/C compressor off @ WOT and high loading)
Can control both a 4L60E and 4L80E
I second Fast's point regarding the improved driveability and performance. Since I installed and tuned EBL in my Xfire, the car has added 3mph in trap speed up to 105. I hope to go to the track this weekend and am expecting another 2-3mph trap speed after lowering the AFR for WOT.
I guess lately I've been hearing a lot of bashing of the 8746 going on and everyone being told to use Rbob's EBL. While I appreciate all that Rbob has done and agree that it's great technology, when I see someone immediately referred to using the EBL when all they have is bolt-ons, I don't see it as a necessary step. I agree the 8746 doesn't have the high RPM tunability that I'd like to see and AE is a bit lacking, but for a basically stock car, the stock computer does fine. Dominic and Fast, I think you guys are definitely at a power level far above a bolt on 305 car, or even one with a MILD cam like the combo I'm running. Using the EBL on a stock-ish car is like killing an anthill with a bazooka (a technique that, I confess, I do have a knack for). Apologies for hijacking the thread.
I second Fast's point regarding the improved driveability and performance. Since I installed and tuned EBL in my Xfire, the car has added 3mph in trap speed up to 105. I hope to go to the track this weekend and am expecting another 2-3mph trap speed after lowering the AFR for WOT.
I am suprised to see how well my engine is pulling down around 12-12.4:1 a/f ratio as well. I've even experimented down to 11.5:1 in the mid-range and in all honesty that still seems fine.
Quote:
Originally Posted by TonyC
I when I see someone immediately referred to using the EBL when all they have is bolt-ons, I don't see it as a necessary step. I agree the 8746 doesn't have the high RPM tunability that I'd like to see and AE is a bit lacking, but for a basically stock car, the stock computer does fine. Dominic and Fast, I think you guys are definitely at a power level far above a bolt on 305 car, or even one with a MILD cam like the combo I'm running. Using the EBL on a stock-ish car is like killing an anthill with a bazooka (a technique that, I confess, I do have a knack for). Apologies for hijacking the thread.
I don't necessarily agree with this statement either. I have a 3.1 MPFI (TBI setup on top) in my 1987 GMC Jimmy in place of the 2.8 TBI. It is now being run with the EBL setup. I can honestly say the tuned EBL setup did more for the truck than the 2.8 to 3.1 swap OR the Pacemaker headers did.
I don't necessarily agree with this statement either. I have a 3.1 MPFI (TBI setup on top) in my 1987 GMC Jimmy in place of the 2.8 TBI. It is now being run with the EBL setup. I can honestly say the tuned EBL setup did more for the truck than the 2.8 to 3.1 swap OR the Pacemaker headers did.
Any more details? Did you try tuning with the stock ECM? Dyno data? Where did it make more power with the EBL? I have a lot of trouble believing that to be honest with you so more data would be useful.
Any more details? Did you try tuning with the stock ECM? Dyno data? Where did it make more power with the EBL? I have a lot of trouble believing that to be honest with you so more data would be useful.
Yes I did, I hacked the stock "429" and tuned for the displacement, injector, and cam change, using WINALDL. In all honesty the peak dyno numbers were not all that much different. Power from 4,000-6,000 was improved over the stock ECM. At 6,000 the tuned stock ECM was down nearly 15 RWHP. The difference is in how smooth the engine runs and the throttle response. The EBL runs much better under a wider array of conditions than the stock ECM did. The "429" does not have highway mode, the EBL does. With the EBL and lean cruise, despite how small the 3.1 is and the 4,500 lbs truck, I was able to squeeze out another 3 mpg highway from it. The 3.1 regularly gets 24 mpg highway in a 4,500 lbs aerodynamic brick.
I will use this snap shot to demonstrate, using the EBL display, my 3.1 free-reving can reach redline BEFORE the throttle can be fully depressed and released!
Yes I did, I hacked the stock "429" and tuned for the displacement, injector, and cam change, using WINALDL. In all honesty the peak dyno numbers were not all that much different. Power from 4,000-6,000 was improved over the stock ECM. At 6,000 the tuned stock ECM was down nearly 15 RWHP. The difference is in how smooth the engine runs and the throttle response. The EBL runs much better under a wider array of conditions than the stock ECM did. The "429" does not have highway mode, the EBL does. With the EBL and lean cruise, despite how small the 3.1 is and the 4,500 lbs truck, I was able to squeeze out another 3 mpg highway from it. The 3.1 regularly gets 24 mpg highway in a 4,500 lbs aerodynamic brick.
I will use this snap shot to demonstrate, using the EBL display, my 3.1 free-reving can reach redline BEFORE the throttle can be fully depressed and released!
Fast,
Thanks for posting that up. This doesn't necessarily support that a 746' isn't adequate for a 305 in that, not many 305 TBI's without a serious cam/head change make power above 5000-5200 or so. The 746' also has highway mode ability. As far as the AE goes, there is some to be gained by ditching the 746' (with AE's sensitivity to manifold temp) but there are many other different modifications that can be done to the engine to get more power without focusing on those 5 transient horsepower that only get used on tip in. Granted new ECU will continue paying off as you keep adding more mods, but as I was saying, at a minor bolt-on level, the 746' can do the trick. When we get Nic's car on the dyno I'm interested to see what it does, maybe I can convince him to let me try out his EBL on my car and we can do a back to back comparison. Anyways, thanks for posting that up and best of luck burying that thing in the 11's!
If that is accurate data analysis I believe you have an air restriction somewhere. You are showing 92KPA at 100% throttle. Looks to me there is a restriction somewhere and you are leaving power on the table.
Mine is 98KPA at 6150rpm and wot and I'm looking to fix that.
If that is accurate data analysis I believe you have an air restriction somewhere. You are showing 92KPA at 100% throttle. Looks to me there is a restriction somewhere and you are leaving power on the table.
Mine is 98KPA at 6150rpm and wot and I'm looking to fix that.
That is a snapshot from the EBL datalogging software.
Did you not notice the 223% injector duty cycle? Keep in mind this was a 3.1 underneath stock 2.8 TBI stuff. The throttle body has TINY bores and the injectors are only 36 lb/hr each. A 4.3 TBI unit fixed both problems.
All I have to say is it is about damn time you took one of your TBI creations and put it between the fenders of a 3rd gen. This is proof that TBI can be made to run with the big boys. My congrats goes to you and only further drives me to finish my LT4 hotcam LO3 project. It should help solve what one can do with ported 187's as questioned above.
312 @11.8? How much Nitrous? Oh and that's not C6 times at least not Z06 times.............need to knock another second off.
z06's run 11.6ish.. no need to drop a whole second.. if they add some sticky tires on the camaro, they will be in the low 11's.. and if you read, there is no nitrous.. the car is just about 600+lbs lighter then most others..
__________________
1984 Trans Am
385sbc(RIP)/t-5/4.30-9"
1.69-7.44-11.65 @ 116
next up-->383 with mild upgrades
Fast,
Thanks for posting that up. This doesn't necessarily support that a 746' isn't adequate for a 305 in that, not many 305 TBI's without a serious cam/head change make power above 5000-5200 or so. The 746' also has highway mode ability. As far as the AE goes, there is some to be gained by ditching the 746' (with AE's sensitivity to manifold temp) but there are many other different modifications that can be done to the engine to get more power without focusing on those 5 transient horsepower that only get used on tip in. Granted new ECU will continue paying off as you keep adding more mods, but as I was saying, at a minor bolt-on level, the 746' can do the trick. When we get Nic's car on the dyno I'm interested to see what it does, maybe I can convince him to let me try out his EBL on my car and we can do a back to back comparison. Anyways, thanks for posting that up and best of luck burying that thing in the 11's!
Tony
Tony,
EBL IS an 8746 or a 7747. Its the code that RBob re-wrote for it plus Lockers
which allows you to scan at 17frames/sec vs. 1frame/sec for a 7747. That alone makes it worth the money. Any time you add greater "granularity" to the code, like VE in 5kPA increments, and RPMs in 100rpm increments, you're going to get a better running motor. Stock or mod doesn't matter. Bob's code updates the stuff GM did 20 years ago. So nobody is "dissing" the 8746.
EBL IS an 8746 or a 7747. Its the code that RBob re-wrote for it plus Lockers
which allows you to scan at 17frames/sec vs. 1frame/sec for a 7747. That alone makes it worth the money. Any time you add greater "granularity" to the code, like VE in 5kPA increments, and RPMs in 100rpm increments, you're going to get a better running motor. Stock or mod doesn't matter. Bob's code updates the stuff GM did 20 years ago. So nobody is "dissing" the 8746.
Which is exactly my point. The engine simply runs better all around. Same with the TBI PCM.
The 8746/299/7747, etc do not even have a fuel table above 3,600 rpm, just an adder table.
Oh and that's not C6 times at least not Z06 times. need to knock another second off.
With a set of slicks, and excellent driver, sure. But on an average though, you are mistaken. The car above was able to make one pass before getting booted, and the sixty foot wasn't that glorious, to be honest. When you factor in slicks, w/better launch, yes, it's definitely in LS7 territory....
__________________ 2009 Corvette ZO6: Black w/Black Leather, F1R Coming.... 1990 Trans Am GTA: Black w/Black Leather, 305 w/T-76, 200R4.... 1989 Trans Am TTA: White w/Tan Leather, 3.8 SFI Turbo, 200R4....
That must be factored into the equation. Good times though. 
This is proof that TBI can be made to run with the big boys. My congrats goes to you and only further drives me to finish my LT4 hotcam LO3 project. It should help solve what one can do with ported 187's as questioned above. 
