312 TBI Track times (11.8 @ 119.1)
 

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.


Block = 1983 4-Bolt main 305 (14010203 casting), Bored .040" over, Torque plate honed, Decked .025", ARP Main Studs, Align Bored

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

Camshaft = Comp retrofit roller XFI280-H13 (280/288 @ .006, 230/233 @ .050, .576/.570" lift with 1.6:1 rocker, 113 LSA, 106 ICL) Cloyes Double roller timing set

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)

RPM------HP----TQ
2,400----147----323
2,600----166----336
2,800----185----347
3,000----207----362
3,200----223----365
3,400----238----368
3,600----263----384
3,800----281----388
4,000----301----395
4,200----322----403
4,400----347----414
4,600----363----414
4,800----378----413
5,000----382----401
5,200----393----397
5,400----401----390
5,600----410----385
5,800----417----378
6,000----421----369
6,200----422----357
6,400----423----347
6,600----419----333

That is 423 FWHP @ 6,500 and 415 ft/lbs @ 4,500.


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.


This is what the timeslip read

--RT = .380s
0060'= 1.95s
0330'= 5.11s @ 71.7 mph
0660'= 7.65s @ 96.2 mph
1000'= 9.94s @ 104.3 mph
1320'= 11.83 @ 119.1 mph

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

Re: 312 TBI Track times (11.8 @ 119.1)
 

holy $hit!!!!!!!!!! that thing is fast!!!! imagine if you add a set of drag radials.. low 11's!! that is a car i wouldnt want to line up with..

good job :thumbsup:

Re: 312 TBI Track times (11.8 @ 119.1)
 

Goodyear Potenza?

Re: 312 TBI Track times (11.8 @ 119.1)
 

:idiot:

Me getting smacked of course, sorry for the act of stupidity. Bridestone Potenza, sound better, lol. Dunno why I had Goodyear on the Brain.

Re: 312 TBI Track times (11.8 @ 119.1)
 

:D

Wow (I can't think of what else to say).

RBob.

Re: 312 TBI Track times (11.8 @ 119.1)
 

Daammmmnnnnn! Thats fast, especially for a rebuilt 305. Very nice...

Re: 312 TBI Track times (11.8 @ 119.1)
 

Does this mean that TBI is not junk? And the inevitable followup question: is TPI still better than TBI now?

And does this mean that it's OK to build a 305 now?

I won't even ask how fast the car would have gone with ported 187s....

Humor aside: That's awesome. Conrgrats on having your first 3rdgen into the 11s with only a 305.

Re: 312 TBI Track times (11.8 @ 119.1)
 

There's about as much similarity between the 280XFI and Hotcam as there is between an apple and an orange.

Re: 312 TBI Track times (11.8 @ 119.1)
 

That's awesome. That's a freakin' HUGE cam though.

I'm running 68# injectors at 24 psi, but I have a much smaller cam in my 350. Thinking about using the juice though.

Re: 312 TBI Track times (11.8 @ 119.1)
 

Oops. 218/228 degs on the Hotcam vs 230/236 as above.... right you are.

Re: 312 TBI Track times (11.8 @ 119.1)
 

That car is lighter than light.:eek: That must be factored into the equation. Good times though.

Re: 312 TBI Track times (11.8 @ 119.1)
 

:cool: :driving:

Re: 312 TBI Track times (11.8 @ 119.1)
 

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.

Re: 312 TBI Track times (11.8 @ 119.1)
 

Scan of said timeslip?

Re: 312 TBI Track times (11.8 @ 119.1)
 

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.

Re: 312 TBI Track times (11.8 @ 119.1)
 

wow, amazing numbers. budget too, which makes it that much more impressive. gives us poor people something to look up to.

Re: 312 TBI Track times (11.8 @ 119.1)
 

Don't bet on it...remember only a select few could ever accomplish that.

Re: 312 TBI Track times (11.8 @ 119.1)
 

how much does that car weigh?

Re: 312 TBI Track times (11.8 @ 119.1)
 

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. :)

Re: 312 TBI Track times (11.8 @ 119.1)
 

I know that it would go faster with a higher shift point, but we are running into centrifical clutch apply in 2nd gear above about 6,400 rpm.

I wish I had a scan of said time slip, my brother has it and is without a scanner.

This sound clip dates back to the engine dyno almost 1 year ago.

http://youtube.com/watch?v=6XLXwAXkDHo

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.

Re: 312 TBI Track times (11.8 @ 119.1)
 

I fell in love with that engine from the video you hosted on you tube. 11.8 with a 3.23 rear end too?

Re: 312 TBI Track times (11.8 @ 119.1)
 

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.... ;)
----------
... wait til Prevost see's this lol!

Re: 312 TBI Track times (11.8 @ 119.1)
 

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.

Re: 312 TBI Track times (11.8 @ 119.1)
 

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.

Re: 312 TBI Track times (11.8 @ 119.1)
 

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 :nod:

Re: 312 TBI Track times (11.8 @ 119.1)
 

10.7:1 compression is kinda tough to do on pump gas isnt it? :confused:

Re: 312 TBI Track times (11.8 @ 119.1)
 

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.

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.

Re: 312 TBI Track times (11.8 @ 119.1)
 

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.

Re: 312 TBI Track times (11.8 @ 119.1)
 

312 @11.8? How much Nitrous? Oh and that's not C6 times at least not Z06 times.............need to knock another second off.

Re: 312 TBI Track times (11.8 @ 119.1)
 

Given the engine combo and weight of the car, I dont have much trouble believing it dipped into the 11's.

Re: 312 TBI Track times (11.8 @ 119.1)
 

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.

Re: 312 TBI Track times (11.8 @ 119.1)
 

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.

Re: 312 TBI Track times (11.8 @ 119.1)
 

AWESOME! And EBL was running it. WOW! Great Work.

Re: 312 TBI Track times (11.8 @ 119.1)
 

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.


https://www.thirdgen.org/forums/tbi/...6197427-a.html

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.

http://memimage.cardomain.net/member...2_129_full.jpg

Here is a screenshot of the EBL display with it comfortably idling at 700 rpm with 11 in/hg of vacuum present.

http://memimage.cardomain.net/member...72_74_full.jpg

Re: 312 TBI Track times (11.8 @ 119.1)
 

idles at 65 kPA yet closed loop at idle? how is idle quality?

Re: 312 TBI Track times (11.8 @ 119.1)
 

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.

Re: 312 TBI Track times (11.8 @ 119.1)
 

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.
----------
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

This is how a TBI PCM runs

COLD Startup in 20* weather
http://youtube.com/watch?v=FmS1m3zlqHo

Van Accelerating with 3.07 gears (Speedo is calibated for 3.73 gears, have 3.07 so it reads about 15 mph slow)
http://youtube.com/watch?v=koWaPeAu3hg

http://youtube.com/watch?v=GeyY5UZ0V6I

http://youtube.com/watch?v=c6qV9T7ZCOI

The traffic is moving roughly 80 in this video
http://youtube.com/watch?v=e3bfNJYT1I4

This is what a ZZ4 cam sounds like at 850 rpm idling cold.
http://youtube.com/watch?v=wRehD8He18E

Re: 312 TBI Track times (11.8 @ 119.1)
 

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.

Re: 312 TBI Track times (11.8 @ 119.1)
 

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.

Re: 312 TBI Track times (11.8 @ 119.1)
 

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.

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.

Re: 312 TBI Track times (11.8 @ 119.1)
 

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.

Re: 312 TBI Track times (11.8 @ 119.1)
 

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!

https://www.thirdgen.org/forums/atta...use-reving.jpg

https://www.thirdgen.org/forums/atta...-v6-reving.jpg

Re: 312 TBI Track times (11.8 @ 119.1)
 

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

Re: 312 TBI Track times (11.8 @ 119.1)
 

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. :)

Re: 312 TBI Track times (11.8 @ 119.1)
 

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.

Re: 312 TBI Track times (11.8 @ 119.1)
 

Fast,

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. :lmao: 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.

Re: 312 TBI Track times (11.8 @ 119.1)
 

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..

Re: 312 TBI Track times (11.8 @ 119.1)
 

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.

Re: 312 TBI Track times (11.8 @ 119.1)
 

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.

Re: 312 TBI Track times (11.8 @ 119.1)
 

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....