bkaltec

Whats up everyone. I have a boat that I have restored and built a new engine for as well. It origionally had a 305 sbc carbed engine in it but it blew or froze up. So I decided to amp it up with a fresh built 350.

So far the engine is...
Bored 30 over
Vortec heads
272dur .450lift cam
Flat top pistons
Roller rockers
Roller lifters
Stock TBI setup with EBL

Ive been playing with the tuning for a little while now and think im on to a decent tune. But i may have just ran out of fuel to keep giving it power. The engine runs beautifuly at idle and ~ok accelerating. However its really struggling at top end, I only get about 4K rpm out of it at WOT. It sounds like its running strong, but i know it will run much better for two reasons; one is it ran a little better with advanced timing and the stock computer at top end, and its a very healthy engine for a 19 foot runabout boat.

So my plan is to first bump up the fuel pressure regulator and try to see if i can get some more fuel that way. If that dosnt work, id like to get a 454 throttle body and bore the manifold for that. BUT im not an experienced tuner. So my tune may be flawed to hell for all i know.

As far as the tune goes, i have a few issues. First, im basicaly using modified EBL_F_3001 bin with modified vortec SA tables and modified VE tables. I tried messing with the BPC and INJ constants and tables, but any changes i made only worsened the performance? I dont have a VRFPR so i dont understand why it works so well.
And second, im unable to get it to learn the VE tables, Ive custom modified them so far and it seems to perform pretty well, but im sure it coulbe be better. Heres a little snap of the data log.




And a couple pics of the boat for the fun of it.

RBob

iTrader: (1)

For the VE Learn to work need to have either a NB O2 sensor or a WB O2 set up. In the screen shot the NB shows 460 mV, which means that the ECM isn't seeing a sensor. Although not sure if the hulled 3rd gen exhaust is set up to use one.

Before adding spark timing get the fueling in line. Make sure that the fuel pressure isn't dropping off. A standard Delco TPI pump or a Walbro 190 LPH pump are decent choices.

Then estimate the HP and figure out how much injector is required. Then either change injectors or increase the fuel pressure to suit.

In the screen shot at 3550 RPM, the injectors are at 60% DC. Which is OK for that RPM. But we also don't know what the AFR is. It may be rich, correct, or lean. And most likely the peak RPM will be higher. Which puts additional constraints on the injector duty cycle.

See the TBI Fueling page on my site for more info on setting up the fueling.

Then once the fuel & AFR is OK, move on to adding some spark advance.

RBob.

bkaltec

Im using a fuel pump for a MPFI volvo penta engine, so im sure i have plenty of pressure. The fuel pump unit itself uses a pump to pull fuel from the tank, and a second pump for high pressure to the engine with a bult in return for the extra fuel. So my next step would be a new fuel pressure regulator, it says on your site the 94/95 year tbi used 30psi fpr's so i think that would be the best. My tbi unit is from a 93 suburban, i would assume it has 61#/hr injectors.

While i was out the other day i advanced the spark timing in the 3200+ rpm range till it barly started knocking, then backed off. It still wouldnt run any faster, so im betting its leaned out.

I dont have any way to put an 02 sensor in without some crazy modifications. Is there a way i can trick the computer to thinking it has an 02 sensor, and still get accurate VE corrections? Or is it using the afr from the 02 sensor to adjust the values. I thought it could learn from the BLM only?

RBob

iTrader: (1)

Only the BBC (454) 94/95 TBI units have the 30 psi regulator. Along with 46#/hr injectors (at 13 psi).

For the BLMs to move the ECM needs a NB O2 sensor input. So can't do an auto VE Learn unless an O2 sensor of some nature is present.

RBob.

bkaltec

Well i modded my fuel pressure regulator with a new spring, which i estimate is about twice as strong. But i dont have any test port or fuel pressure tester, so im unsure where i sit as far as pressure goes.

I hope im not up too high in pressure, but ill have to wait to see once i get back on the water. I started it up and it ran great, but its not under any load.

Heres a little info from the engine after i changed the fuel pressure. This is just being reved under no load, do you think duty cycle and sPW be ok under load at maybe 5000 rpm?

RBob

iTrader: (1)

Can't tell unless the AFR is correct and the engine is under load. Note that by increasing the injector flow rate (higher fuel pressure), the BPC vs VAC table needs to be changed and the AE PW tables need to be reduced.

RBob.

bkaltec

Got it running well through the whole rpm range. It will pop through the throttle body when I pull the throttle back too quickly. Dont know if that means it leans out too much or what. Still need to look into that some.

However im hitting a barrier at 4200 rpm. It just wont go any further than that, and i think its because im simply out of power. Im using a stock 5.7 tbi unit. Will a 454 TBI unit give any significant hp/torq gains over a 5.7 with my engine?

RBob

iTrader: (1)

Pop through TB on quick throttle opening: need to add more AE. This can be done via the PW tables and via the RPM table. I mention the RPM table as the AE is typically tapered off as the RPM increases. And this tapering may need to be changed.

To check if the TB and air intake system for restriction. Key-on, engine-off, read the MAP value. This is barometric pressure. Then at WOT & red-line read the MAP value. Both of these may be had from a data log.

The difference between the two MAP values is the drop through the induction system (air cleaner, duct, and TB). Anything more then a 10 KPa difference is getting high.

Check that the throttle blades are fully open at WOT. Can be checked engine-off.

Check that the fuel pressure holds during quick throttle openings and at high RPM, high load. Even the slightest drop in fuel pressure is not acceptable on an EFI set up.

RBob.

Ronny

iTrader: (1)

RBob: Are the marine engines then OL and the tune is calibrated on a dyno? If so are there not available any .bins for a TBI vortec marine engine available? I would suspect the power band is somewhat linear. Heavier boats would use same tune just change (lessen) pitch of prop to maintain same RPM at WOT.

RBob

iTrader: (1)

I don't know much about boat systems. As for closed vs open loop, depends upon the exhaust manifold set up. With water cooled manifolds can't easily run an O2 sensor.

The MEFI3 ECM has the capability to run closed loop. But most (all?) installations don't use an O2 sensor. Even the RamJet auto engine package didn't come with closed loop fueling. That is/was an option.

RBob.

Ronny

iTrader: (1)

any marine vortec .bins available that you know of ?

RBob

iTrader: (1)

None that I know of.

RBob.

bkaltec

It pops after I close the throttle significantly. Acceleration is good.


Red line as in no load out of gear up to 6000+RPM?

RBob

iTrader: (1)

See, I mentioned I didn't know much about boats. Pulling back is closing throttle, eh? You know, now that I think about it, yes, pushing the throttle forward is more go. Just like an aero-plane. I've been on boats from time to time. But with sails there really isn't a throttle

OK, seriously now. On decel there is a decel enleanment (DE). Try to reduce the level of enleanment. Increasing either the "DE - Enleanment Factor" or the "DE - Coolant Factor" table will reduce the enleanment during throttle closing.

The "DE - Enleanment Factor" is a global change, which is where i would start.

This should alleviate the lean pop out the TBI on decel. If not, then a SA change is required.


> Red line as in no load out of gear up to 6000+RPM?

With load. IOW, go out and open it up and cruise. At the point where she doesn't pull any more, tap the space bar a few times. This will put a marker in the data log. Then check to see what the MAP value is. And compare it to the MAP value at key-on, engine-off.

RBob.

Fast355

iTrader: (2)

Keep in mind that the timing you need for a boat is VERY, VERY, VERY different than a car. A boat typically does not run vacuum advance. They run mechanical/centrifical advance only.

On a side note....TBI setups do not like the choker collar that you have between the TBI and flame arrester.

bkaltec

It will still run properly being controled by a computer, but its always under a higher load than a car.

I checked some logs and saw ive never gone over 90kpa under full load at 4200 rpm. And with the engine off the map reads 100kpa.

So ill try a few things including your suggestion Fast355 to try and provide more airflow to the engine.


Ill try to adjust the DE tables. I need to install an IAT sensor still, I adjusted the IAT/CTS blend filter table to use CTS for compenstation, but it still pops.

bkaltec

I have some major problems recently. No tuning done before these issues occured. The backfire throuth the intake is getting insane, above 2500 rpm its horrible and wont let the engine run.

I think this is caused by the timing, which is another strange issue. Its knocking like crazy. Idle it runs fine, but above 1500rpm it ranks up 255 counts in no time on any spot on the table. About 8 deg retard all the time above 1500rpm as well. My first guess would be a bad knock sensor, so i tried unplugging it and no effect. Could the ESC module have gone bad? No malf codes that i remember.

Just trying to get an idea of where to start before I start messing with it. Any suggestions would be greatly appreciated.

RBob

iTrader: (1)

Sounds like a lack of fuel pressure/delivery.

Is it really knocking, or is it just knock counts? You can eliminate any knock retard by zero'ing out the two max retard tables in the "SA - " section of parameters.

RBob.

71403

Have you verified full bat+ voltage at the coil under WOT?

A lot of carb'd boat guys were running the small-cap HEI (and no EST control) since marine engine doesn't need much of an advance curve. Could try a WOT run with the set timing connector open as sanity check.

Not sure if OMC does it, but Mercruiser has a momentary ign kill switch on the throttle linkage to make shifting in/out of gear at idle easier. Depending on where/how/if it's connected it could be a factor.

Small cap HEI has nasty habit of corrosion on the pickup wires & pins. Marine environment doesn't help.

bkaltec

It was really knocking. Could hear it pinging clearly.


Ill test the voltages.

My timing was so f'd up ill need to do a test run after adjusting it. The whole electronics system has been replaced with the tbi setup. The previous engine had vacuum advance though no parts were reused.

The kill switch on the shifting linkage works great, I made sure it was good after adjusting my steering a little while back. That would prevent the engine from running entirely anyway.

Ill open up the cap, it does get tons of condensation on the engine by morning. Running on the lake it dosnt get wet at all.


Thanks for the suggestions guys, ill probably give it a run tomorrow afternoon.

bkaltec

So to keep things clear i double posted.

After a good combing over the engine today, I found many issues.

First, I re-adjusted the valve lash. It seemed a little noisy and proved to make a little improvement. It has a tad more compression and sounds beautiful now.

Second was the timing. HOLY crap it was way off. I adjusted it a while ago, and I guess I misread the TDC guage as it counts by 4's. I had it set to where i thought it was 10*, but was more like 16-20*...oops. Also my SA Initial Advance was set to 6* so there was a good ~10* added to the sa unknowningly.

Third, I found the alternator unplugged. I dont know if it was from me removing the valve covers, or if its been that way for the last few times it was out. But a lack of voltage could have caused all of my problems. IE low fuel pressure, insufficient spark. I had probelms with the alt coming unplugged before, ill need to get some different pluggs.

Ill have more information and hopfully good datalogs after tomorrow.

bkaltec

I seem to have hit the sweet spot, it ran better and smoother than ever! No popping at all and no ticking or pinging. Although it wouldnt idle for crap, lots of surging and dieing.

Did a little tuning to the idle, it still surges a little, but nothing thats unbarable and it dosnt die anymore. The cam may be a little thick for a great idle.

So now it idles good and runs awsome. I think ill leave it for the weekend, and maybe spend some time perfecting the timing next week. Hopfully I can find a 454 tb to slap on it, get a little more top end.

bkaltec

Started getting parts to do the swapout from a 5.7 throttle body to a 7.4 throttle body.

A small list of what ive purchased so far:
-A large K&N flame arrestor to replace my tiny stock one from the 305. Its also tall enough to accomidate the injector pod and eliminate the collar adapter thing that came with the tbi's.
-TBI Injector pod spacer. I heard this helps keep the fuel spray from hitting the throttle blades, as well as open up the gap between the injectors and throttle bores.
-TBI Rebuild kit.





The throttle body was shiped today and should be here thursday (hopefully). Its a 93 year with the 80#/hr injectors. Ill be using my modified fpr which is about 20~30psi so hopfully ill be above 100#/hr.

Once i get that and have it rebuilt, ill remove my gmpp vortec intake and port match the throttle body holes. I thought about having it done professionally, but I dont see why i couldnt do it. Thoughts?

More updates as I progress.

xch3no2

Consider carving up a tbi spacer for the transition, some have had problems when boring the manifold larger.

bkaltec

The Throttle Body plane is solid, so boring out the ports should be a big deal, but ill keep it in mind.

I am worried a little about fuel delivery. Ive modified the fpr for the 55#/hr injectors. Hopfully bumping up to 75#/hr wont flood the engine at idle since i dont have a vacuum referenced fpr.

Got the throttle body in a few days ago and rebuilt it. The bore size is considerable compaired to the 5.7 tb.
Still need to port match the intake manifold and put it all together.
Heres some pictures for viewing pleasure.

RBob

iTrader: (1)

Looking good. Note that the 5.7l TBI unit you have has 61#/hr injectors (org/blk color coded).

RBob.

bkaltec

Got my new exhaust in and started on the mods, had several nice warm days to make good progress.

Took apart the intake manifold to open up the throttle bores and removed the old exhaust manifolds. After disassembling the exhaust, I found that one of the water flaps had blown out, im guessing its blocking some of the flow. Bored out the intake myself and it didnt turn out too bad id say. Bolted the intake and the new manifolds on. Started up immediatly and now im excited to do some tuning.

Today I got the exhaust tips roughed in. Still have a list of small things that need to be completed, but nothing too difficult.

bkaltec

Got it in the water for the first time this season yesturday. Ran much better than i expected. Picked up 1k rpm with the new exhaust and 454 throttle body, couldnt be happier.

Couple crapy quality videos, but fun to watch i think. Loud as hell as you can see here.