Fast355

iTrader: (2)

A friend of mine that I have spent the last 2 weeks working on his chip and the last 2 months on other things with his car, just stopped by after running at the track tonight. The results are great if you ask me. Too bad second gear in his 700r4 is now practically gone.

His engine is a 305 roller block bored .040" over for 312 CID. It has Speed Pro flattop pistons in it, forged rods, and a forged crank. The whole rotating assembly is balanced. On top are my second set of "193" 350 TBI heads (probably better than my first if I was to guess). The engine has a stock 350 vortec camshaft in place of the smaller peanut cam (too small if you ask me, but it is what he had). The car has edelbrock headers and a Y-pipe meant for a L98 car. The catalytic converter is a newer high-flow unit. The exhuaust is 3" from the catalytic converter back. The real power is from what is on top. A weiand 142 stuffing 7 psi of boost into the engine. The TBI is stock but houses a pair of 454 injectors. Knowing that boost on a roots is linear with RPM the tables were not very difficult to setup. A MSD series boostmaster box is providing a boost referenced timing retard of 2* per pound of boost. It is also using a vacuum compensated regulator that also just happens to boost fuel pressure when boost is applied. At 7 psi of boost the fuel pressure is roughly 20 lbs; above the throttle blades which is above the supercharger and therefore never sees boost. There is no chance that this engine is lean, if anything it is super rich and the timing is pretty retarded.

Other specifics on the car are a 700r4 with the stock stall and a 3.23 posi rear end. I can't remember the tires off hand but am thinking it is the BFG Drag Radials. Oh yeah this is in a 1989 Camaro RS.

Enough with the typing here are the numbers.

60'-----1.99s
1/8-----8.35 @ 82.9
1/4-----13.0 @ 108.0

BronYrAur

iTrader: (1)

That's awesome! First real successful boosted TBI application I've seen, and not too shabby with that small of a cam, stock TBI and swirl port heads. I've always been interested in a blower combo like that, good job

Fast355

iTrader: (2)

Next up is my G20. Wonder if I can get that thing from the low 15s or high 14s into the 13s with a blower and a gear change?

If I go blower I am going to a 177 and ditching my EGR valve. The 142 from weiand was meant for a TBI truck and had all the neccessary stuff to retain the emissions controls.

kdrolt

A stock 350 Vortec (L31) cam is the same one used in the Bcar 94-96 Impala SS. 191/196 deg i/e, 0.418"/0.430" lift, 111.5 deg LSA --- so it is pretty mild but a lot better than the peanut cam. IIRC that same cam -- Bcar LT1//L31 -- was used on the L30, which is the Vortec version of the 305, and that engine with that cam was rated at 230 fwhp.

To run 13.0 @ 108 in an Fcar means 340+ fwhp so your porting exercise on the 193 heads + cam makes the 305 good for approx 240 fwhp NA (I'm assuming +10 above stock L30), and then another 100 extra fwhp due to the 7 psi boost (7 psi is roughly half of 1 atm, i.e. half of 14.7 psi, so you get 120 extra fwhp, but the extra heating from the boost reduces the output from 120 --- my swag is +100 hp from the boost). And 108 mph trap suggests that the 13.0 could be bettered.

I wonder what the car would run without the boost. Low 14s? Nice job.

Fast355

iTrader: (2)

Pics

This is not the engine but it looks identical. Only difference is his has a TBI instead of a carb, a HEI EST distributer, and an EGR valve on the rear driverside of the engine, and a few more wires. Oh and it still has A/C and a serpentine belt setup.

Fast355

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Another

Fast355

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Too big?

Fast355

iTrader: (2)

Lets try them again. Engine looks nearly identical to this one.

Fast355

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Stock 305 prior to being touched.

Fast355

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Weiand 142 meant for a TBI truck.

Fast355

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Another

Fast355

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Regulator

Fast355

iTrader: (2)

I am thinking that flywheel output is less than 350 horsepower at 5,000 or so but the little 305 is probably making 450-475 ft/lbs of torque around 3,000 or so.

It is impressive when you drive it, just how flat to torque curve really is. This car pulls in OD or 3rd nearly as good as it pulls in 1st and 2nd.

Cadillac

Awesome. Thanks for sparking the hope in all of us.

hehe

JPrevost

Cool deal.
What did you set the injector constant too? Also, why bother with boost referenced fuel pressure and a retard box? The retard could easily be sold for a 2-bar map sensor giving you more control over the exact timing under boost .
Also, since the TBI is above the blower the tuning would be a lot easier without referencing it to the blower pressure. The only time you would need to reference the fuel pressure is if the injectors see that differential in pressure, which they wouldn't being above. This way you won't have the funky looking VE table and PE AFR tuning headaches. Sure it'll tune okay but why make life harder than it has to be.
Note to self; Find 4 more mph in my n/a stock heads 350 so I don't get shown up by a blown and punched 305

Dewey316

I just trapped at 107 with little spray on my 305

Fast355

iTrader: (2)

The base pulsewidth is around 85 as that is where it seems to do the best with the wideband. I am getting about 11.3-11.6:1 a/f mix now. Yes its rich.

You have me interested as to whether I should move the vacuum line to the front of the TBI instead of the intake under the blower. I know that not having the injectors referenced would probably be better, but what we were trying to do is get the engine enough fuel to not run lean. Even with the cam change, the blower, change in heads, headers, exhaust, and the 454 injectors the engine fired to life and actually idled with no changes other than the BPWC. My other theory is that the injectors need the extra pressure to atomize the fuel correctly. The 454 injectors are actually out of my G20 as I switched back to the 65 lb/hrs at 20 psi.

The VE table do look a little weird like you stated. I actually had to pull fuel out of the VE tables when the MAP dropped and boost came in.

Cool thing about the roots while tuning is the blower boosts immediately, without lag, and boost is proportional to throttle position and RPM. You are not going to see boost spikes such as a turbo when it goes into high gear.

Thing I am worried about is getting the ECM to recognize the 2 bar MAP sensor. I tried once on a turbo 3.1 and got a MAP sensor code the second the engine would go into boost. I never could get my Jimmys ECM to recognize boost.

z71stroker

so if I wanted to run a roots style blower for TBI on vortecs i am just SOL? i want a power adder now lol, bleh, shoulda gone with sportsman 2's !! nice work, you and your friend fast.

BronYrAur

iTrader: (1)

What kind of hood is he using?

Street Lethal

iTrader: (16)

You had me going for a second, I thought you guys accomplished 13 seconds flat with a 305-TBI... naturally aspirated.

JPrevost

Nobody said you had to put the blower right ontop of the intake. Just mount the blower over one of the valve covers and fab up some duct work, then you can have a blow through setup that has worked just as well for various guys around the world. I know 3 guys did it here with TPI and Joby has a blow through centerfugal so I'd look at his setup.
With 5.1L and 80# injectors the injector constant should be 92. Then adjust the VE tables to get the logical VE
That's a good reason but why not run the injectors at 20psi all the time? I think you'll be pleasently suprised at how well they operate at low pulse widths.... being only 2 ohm's they're mighty powerful. The only thing you need to be careful with is the voltage at idle. If the idle voltage is low you're going to need to adjust the pulsewidth vs battery voltage table. You should do this anyways and the best method is to get an old battery and disconnect the alternator, watching the wideband at idle adjust the table with an emulator to keep the same AFR. Don't aim for an AFR, just remember what it was at idle with the alternator hooked up. You can also do this with the "lie" to the alternators voltage regulator using a pot (variable resistor) circuit. The GN guys had designed this to give them a little more fuel out of their pumps when they added boost, it can be reversed where you're telling the alternator that the battery voltage is higher than expected... effectively shutting off it's charge and letting the battery voltage drop. Multiple ways to skin a cat.
I wouldn't worry about the map sensor throughing a code. And if it did, you can EASILY change the thresholds of the code since they're in the chip. Or even easier is to disable them but that's not advisable. The 2 bar map sensor is almost half the voltage but with the roots blower your boost is like you said, linear (practically) to RPM and TPS so effectively the 2 bar map sensor will work really well. The only thing to consider about going to a 2 bar map is the baro readings and their effects on the rest of the code. Just disable them if your baro is like mine on the east coast where it stays between 98 and 102kpa.
I think that the 2 bar is worth a shot since it will give you a very "pleasant" chip making changes in the future that much easier. It's worth a shot . Oh, and get that damn thing into the 12's!

Fast355

iTrader: (2)

I have confidence that it will be in the 12s after it gets a built up 700r4 with a 2,000 rpm stall in it. Wonder if the fact the trans went out on the way home had any effect on the times?
This car was still using the stock shift points on the 700r4 for a 1989 RS too.

Time for a corvette governor in the thing to get WOT shift points to 5,500.


Basically what I did on my Jimmy was disable the MAP diagnostics then split the VE, SA, A/Fvs. MAP table in 1/2. Meaning at 50 kPa I was at atmoshperic pressure and 100 kPa would be 10 psi boost. I am sure resolution is a problem, but it is better than the solution on the camaro with.

JPrevost

I've yet to really feel any true "resolution" obsticles when tuning with GM's ecm's. I have however found plenty of limitation and the MAP isn't one of them. Even with an 8-bit adc the MAP voltage is seen in 0.02v, that equates to around 0.4kpa resolution. On a 2 bar it's 0.8kpa, still plenty.
It takes a special kind of tuner (**** retentive) when they start complaining about the stock tables not giving them enough granularity... the 8746/7747 VE tables however ARE a problem but everything else is pretty darn good.

smokeycamaro51

does it all fit under the stock hood? Prolly not but im hoping because i really don't want to have to flame the car again.

Fast355

iTrader: (2)

Nope, well it does if you cut a big hole in it.

ShiftyCapone

iTrader: (7)

Wow, what a great set-up there! I wonder how much faster you guys would be with a 350. Your trap speed indicates to me that you can get into the 12's.

steve8586iroc

Nobody mentioned it but wouldn't you also benefit from a larger throttle body for extra air? It would seem that the stock tbi would be a restriction on top of that nice blower.

Steve

odddoylerules

since this guy is hip to tuning chips, did you guys read about the nitrous on the roots blown 454 in hot rod? Could a motor like this benefit from a little squeeze intercooling?

kdrolt

An excellent point. If the 340+ fwhp estimate is legit (and seems like it based on the timeslip) then the stock TBI is limiting the airflow (perhaps also true on Fast355's 355 in the van). Given that the 454 TBI seems to cause so many tuning problems maybe the bored-out Rochester 220 (i.e. the one you have) is a better way to go.