BTW, Yes, the car needs to be washed....

 

Very nice build. You do some nice work.

 

Sounds great!! Congrats.

 

Small update: I *think* I have the transmission leak sorted. It is/was the flared hard lines going into the cooler. Snugged one down a bit more and seems to not be leaking. I did see a small spot on the floor. so I will check the lower fitting, and tighten if needed.

I did a few tuning rounds. Just datalogging, starting it, seeing where it stalls, driving it up and down my street, tweaking, etc. Bigger cam means its less efficient down low, so I've had to take out some fuel/lower VE down in those ranges. I also needed to up the rpm above idle target where it starts controlling idle again. When I would back off the gas, it'd fall and with the default value of 50 rpm, it would not have enough time to transition to the idle circuit. Now it's not stalling when I let go of the gas or come to a stop. So it's making progress.

Took it for a 5 mile drive, seems like its shifting fine and the Yank SS3600 seems perfect. I gave it 1/2 throttle one or two times for a second. Jesus its going to be fast.

We've got rain all week so likely no driving again until the weekend. I'll try to get a video next time its out.

 

I hadn't posted in a while, so here's an update:

Car is driving very well. I am sorting out the typical issues with a build like this. But very happy with it so far. I don't have pics/vids handy, but I'll try to add some later.

1) Transmission tuning is more finicky than in my other swap. Not a major problem, just taking a few more iterations to dial it in. Overall, the gearing (3.33 rear gears) and SS3600 are a very good match for the engine.

2) Traction was an issue at first, but the tires were at 35 PSI from the tire place. Dropped them to 20 PSI, and traction and contact patch are much better. But now I'm getting some tire vibration. I need to see if I can find a sweet spot. These are 315/35/R17 ET Street SS

3) Once I got those items somewhat sorted, I had a strange intermittent that happened a couple times: Hard acceleration (say 60-70% TPS), at about 5000 rpm, suddenly there was no power and the engine got quieter. No trans slip, but almost felt like the trans shifted or something. Anyway, after looking at the datalogs, I found the issue: I'm using the factory LT1 rubber air intake from the throttle body to the air filter. In those cases, it sucked itself flat and blocked all the air from the engine. It's a very flat/over hose, so for now, I used a large heavy zip tie to pull it into a more round shape. That's got enough pressure on it to keep it open wide and the issue is gone. I need to look for a better solution, likely I will custom fab a new air bridge. The space is VERY tight between the hood and the top of the radiator shroud. I have a C6 intake but it can't clear that space, so I need to see if I can heat/cut/weld it to work.

Those issues are minor. The other two might need some more digging/rework

4) Oil pressure isn't quite where I want it. Its OK, but low compared to my 'mystery' LQ4 in my 71 GMC.

I get high 40s cold idle, but this drops to around 28psi hot idle. Then it builds OK with revs, but only to around 50psi or so. I don't have the datalog handy. I'm on 3rd oil change (did one after 10 min of running, and other after a few miles), the first were 5/30 conventional, now running 15/40 T4 rotella conventional. I do not see any aeration of the oil on the dipstick, but I also didn't see any noticeable change in pressure going from the 5/30 to 15/40. Oil filters have been clean and no sparkles. Not really a problem, I just expected a little higher pressure. I can't remember what oil put we put in this engine. I Think a ported stock pump, so it might have a pressure relief/bypass around 50psi. My LQ4 in my other swap is a mystery (Bought from a wrecker with no history) that came full of ARP bolts and a cam and other internals. That one is like 60 psi+ all day.

So, *perhaps* I have the wrong o ring or a small nick? Or its just find. Unfortunately, I can't drop the pan with the engine in place, from what I can see.

5) Fuel pressure is dropping slightly under load. I have the reguator sitting at 59-60psi, and it will ramp down to around 52-55psi under load. It seems to get to 52psi and stay flat there. I'm trying to figure out the weak link there, without scrapping everything. The system *should* handle the fuel demands, but clearly there's an issue somewhere. The setup is as follows:

Aeromotive Stealth 340 in tank. Wiring is 10 gauge back from the alternator stud (alternator is good, keeping 14.5volts), dedicated large relay (OEM, same ones that run the cooling fans), ground wires are beefed up at the tank also (2x grounds with heavy ground cable), upgraded racetronix wiring/connector and bulkhead connectors. The 340 pump is hung in the stock hanger with a new sock. This feeds the stock 3/8 steel hardline, up to a stock (brand new delco) LT1 fuel filter, then to a 16mm->6AN fitting, then -6AN line to the regulator. The regulator is an Aeromotive regulator. I forget the number, its a mini regulator, but supposedly good to 1000 NA horsepower. There is a -6AN line from here to the rail, which is stock LS3. And then a return line from the regulator, also -6AN, back to the stock 3/8 steel line back to the tank.

Anyway, I'll get that sorted once I can get a chance to start troubleshooting.


Overall, it is driving fine. Just need to dial in those items. It stays nice and cool at speed, but does build a little heat at stoplights/very low speeds. So I want to look at my fans and perhaps upgrade them.

 

Looks like you're on your way to sorting it out.

That fuel pressure drop is a mystery. Sounds like you covered the bases. Maybe the pump is having issues? If you had a rising rate regulator (you prob don't), I would say just pump the pressure to the regulator with a bike pump and see if the pump can maintain higher pressure. Maybe pinch the return line and see how the pressure rises? I'm assuming you're logging voltage and it's not dropping when the fuel pressure drops?

 

Yeah, I want to try to do a few things, like perhaps I will adjust the fuel pressure up or down a few PSI, and see if the 'floor' of 52psi stays at 52, or also moves by how much I adjust it. The regulator isn't referenced to the intake (the reference nipple is open to atmosphere, which appears correct per the instructions).

I have monitored the system voltage, and it does not drop. I might see if I can tap and monitor voltage at the fuel pump.

I figure I've got 4 main possibilities:

1) Pump cannot supply enough fuel
2) Feed lines/filter are causing restriction
3) Regulator defective
4) Return lines to restrictive

(Going into engineer mode)

1) Pump I bought new as part of a phantom fuel system, I used the rest of that system in my GMC, but I swapped to a Walbro 255 there, as the 340 would have been overkill for the LQ4. So it's about 6 years old, but was stored new in the box.

2) I would *think* everything is OK here. From my research, the ZR1 guys use the standard fuel lines and filter on builds up/past 500WHP. The C4 ZR1s have dual pumps but use the same single 3/8 steel feed line and filter as far as I know.

3) Could be. I bought new from Summit Racing, so hopefully its a genuine Aeromotive regulator and not a counterfeit.

4) Here I have suspicions. Maybe there's something choking it down, even in the return/orifice sizes in the pump module. I will grab a screenshot but I think the fuel PSI seems to 'stabilize' down around 52 psi, even as RPM goes up. I would expect if the system couldn't keep up with demand, then it would continue to drop.

 

Here is a screenshot

 

So, Red is RPM, purple is fuel pressure (pressure sensor is screwed into the pressure port at the regulator. ) For reference, voltage (at the Holley ECU) is in yellow. And oil pressure is in blue, just left it there, since I was talking about it.

It looks like the regulator 'finds' a level around 52-53 psi under load. Could indicate the return is too small somewhere. Sometimes there's a neck down in a fitting or something. I do have AN6 to 16mm fittings on both the feed and returns. I didn't check the IDs on them, I think they are more designed for power steering lines, so perhaps the ID is a little small.

I believe that if I pull the return -6 AN line from the regulator, and just have that dump into a bucket, that should remove any restrictions. I can see if the regulator stays at 59-60 psi, or if it's really set to 52-53, and it can't regulate based on the flow resrictions.

 

I didn't think that your regulator had a reference nipple. I would take a bicycle or other pump and add pressure to the reference and see what the fuel pressure does. That will tell you max pressure capabilities, but not as much about max flow . Still useful for seeing if a weak pump is the culprit. Not as much for kinks or choke points.

 

Back on post 71, I have the fuel system pics. You can just make out the reference nipple in this pic, on the right side of the regulator.

In that same post, you can see the 16mm to AN fitting. Wondering if that is necking things down too much, by the narrow end where the O-ring goes.

 

Didn't see the regulator before. Sure, put some pressure on there and see what kind of fuel pressure the pump can deliver.

BTW, any pinch points on the return side don't matter. Only the feed side.

On an unrelated note, my regulator is 1:1 rising rate. I feel it's easier for the injectors to supply idle level fuel volumes at lower fuel pressure and higher volumes when needed under boost. Less work for the fuel pump when cruising. My base pressure is 42. Needless to say, yours could be that way also if you connect the reference to manifold pressure, but your tune would need to reflect that.

 

I don't think that is correct. The return side must be able to shed enough flow to regulate. In the extreme case, a blocked return, then the regulator ends up doing nothing and the system would go to deadhead pressure.

What I've seen, is an undersized return can create a 'false' regulated level. Once enough fuel is taken up by the engine, then the return flow is lowered and the return line is no longer a restriction. At that point, the system pressure should drop to the true regulated pressure level.

I believe I can check this simply by dropping the regulation screws and seeing if I can get the system regulating at, say 45 psi. If it can do that, then its not likely restricted on the return size.

 

OK, I'll go along with that logic. So what you're saying is that the return restriction (if real in your case) may be causing you to get a false, artificially high, base pressure and that your low pressure while in boost is actually the base pressure setting.

 

Yes.. except I'm NA, not boosted. (which is why the reference nipple isn't used on my particular setup).

 

From Aeromotive's website:

FAQ - EFI Regulators

1.) After installing a larger (or secondary) fuel pump for my EFI engine, the fuel rail pressure went up and my regulator won’t adjust it back down, what’s wrong?
To understand this problem, it’s helpful to think of a fuel pump as “putting out flow” instead of “putting out pressure”. A bypass regulator restricts the flow, forcing pressure up before allowing fuel to return to the tank, creating fuel pressure and then maintaining it. If pressure won’t come down as the adjusting stud is turned out (counter-clockwise), the regulator may be too small to handle the pump’s flow rate, resulting in a false pressure. Also, check the return line for kinks or obstructions and make sure it’s not too small. Remember, during normal driving (idle and cruise), the regulator and return line together must flow over 99% of the pumps volume back to the tank, without building excessive back pressure.

If the return line or the regulator, or both, are too small for the pump, the resulting fuel pressure is said to be “false-high”. This means pressure is out of the regulator’s control until the return flow is reduced, like at high engine load (WOT), when there’s less fuel on the bypass. This can cause the regulator to seem unable to be adjusted and it will create a pressure drop that looks like the pump is too small. Important: If the regulator will easily adjust 3-5 PSI lower than the desired base pressure, that’s a good indicator the regulator and return line are big enough to do the job.

 

So, I will try to back it down and see if it will drop. But later. This weekend is Woodward cruise, and we'll be out in the GMC enjoying the nice weather

 

i'm in the process of building up stroker LS1 (3.903 bore, 4" stroke) and was referencing your thread. Do you have any concerns with the high static compression ratio? I realize it's just a number and that the dynamic compression depends on the cam profile, but i am quickly realizing that i'll have to be careful about which heads I select with the stroker setup as the extra stroke increases compression by default. Please note, i'm not questioning your decision - just trying to glean some knowledge as i dont really know what i'm doing. Thanks.

edit: my goal is to build a motor that makes good power throughout the rpm range with decent top end, that runs on pump gas (93 octane is fine). Its going into a car that my wife occasionally drives so it needs to have good drivability and be predictable.

 

I hadn't seen this when posted.... but, hmm, not really. I have seen plenty of people get away with compression around 12:1 with 93 octane, which is what we have here in MI. I do try to overly research things before I build, so I had checked into it quote a bit. I also knew that I had the option of moving to E85 if it wasn't manageable.

One thing to consider, is the camshaft. This is where you have some control, as you can alter the dynamic compression. My cam is almost a bit small for a stroker, compared to many, but was selected to put the DCR where I wanted for a pump gas build. I forget the number, but Its in the range of 8.5-8.7 DCR. Again, I had checked into many sources and made sure the number was in a reasonably safe area.

Lastly, I have brought this tune along slowly. I run it richer and with less timing than I do in my cammed LQ4 that I have been tuning for the last 5 years. I am considering to take it to a dyno for dialing in the timing, as that is a bit hard with street tuning. .

 

Minor updates for summer 2022:

I replaced the radiator with a Cold Case dual core, and its running nice an cool. I also swapped the fans for a pair of Spal 12" units, which give around 10-15% more airflow.

I did find that connecting the vacuum nipple to the regulator (and re setting the pressure) now keeps fuel pressure pretty stable at 59-60 psi under all loads.

I also did some airflow testing (because Engineer) on some different intake combos. I have a woodshop in my basement, so I took two 4" lines from my dust collector, tee'd them together and used it to simulate an engine sucking in air. Not perfect, but it should give a relative reading (Dust collectors don't pull as hard of a vacuum as an engine can, but each 4" line can move about 300-350 cfm with my particular collector, so 2 of them is very close to the airflow of an LS motor). ... I used a water column manometer to measure vacuum after the filter. The higher the vacuum reading, the more restriction the intake is creating.

Anyway, I found in my test, I my C4 LT1 Intake (shortened to fit my 102mm throttle body, and cut open to expose the air filter) was the best performer. Slightly behind it was the 6 x 10" K&N round filter from my LQ4 swapped GMC. In last place was my C6 LS3 Intake (note, that filter was used, but did not seem terribly dirty, and I did run compressed air + vacuum on it to try to make sure it was as clean as possible).

There were no significant differences between any intake, with the filters removed. So I retained the C4 intake, but I TIG welded up a 'stent' from thin steel rods which fits inside the section that was collapsing under vacuum, and it seems like its all working fine. Seems OK, but I may still try something better. My last datalog was 98 kPA barometric, and WOT was 95 kPA MAP reading. Next step would be make a modified shroud and duct the filter in from the front of the car.

Oil pressure is stable... ~25-28 hot idle, 55 psi up top. I believe it was a ported stock LS2 pump they used. Oil filter has been clean on each cut, so I'll live with it. I have a Melling 10296 on the shelf if I feel like yanking out the engine.

So, the car is now running with no issues. I've been doing my own tuning, its certainly a bit more finicky compared to the LQ4. Mainly just the start and idle stuff I am dialing in. It runs fantastic on the road. I would like to find a dyno tuner in Michigan that could help get it to the last few percent of the way. Its tricky to even test anything on the road. 1st gear can overwhelm the tires, and 2nd gear doesn't top out until 100mph.