L31 Extreme Budget Build

[L31MaxExpress]

Would TBI benefit from one of these?

It might especially if the pressure is raised a bit but not worth putting in by itself unless the tank is coming out for other reasons.

 

[Scooterwrench]

It might especially if the pressure is raised a bit but not worth putting in by itself unless the tank is coming out for other reasons.

I'm going to have to put a Vortec pump in it to feed that 355 with the 454 TB. I'm not sure yet how much I'm going to have to raise the fuel pressure with 80lb injectors. WOT PW will tell the tale.

 

[PlayingWithTBI]

I'm going to have to put a Vortec pump in it to feed that 355 with the 454 TB. I'm not sure yet how much I'm going to have to raise the fuel pressure with 80lb injectors. WOT PW will tell the tale.

It will be interesting, I put the '4304 injectors (for 91 - 93 74PPH @13 PSI) running at 15 PSI on my 5.7L bored 46mm TB and couldn't get it to idle - my EBL kept shutting them off trying to get AFR to 14.7. I'm running the 5.7L 61LB-ers at 20 PSI (on my 383 now) to make it happy and still get enough fuel @5800 RPM. Good luck with that, I hope it works

 

[L31MaxExpress]

Will the Proflow oscillate north and south of stoich to keep a 3 way catalyst happy?

Here is a screen capture at idle. Belt idler is making a bit of noise that I can now hear with the quieter exhaust. The AFR fluctuates around stoich fairly substantially.

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[Scooterwrench]

It will be interesting, I put the '4304 injectors (for 91 - 93 74PPH @13 PSI) running at 15 PSI on my 5.7L bored 46mm TB and couldn't get it to idle - my EBL kept shutting them off trying to get AFR to 14.7. I'm running the 5.7L 61LB-ers at 20 PSI (on my 383 now) to make it happy and still get enough fuel @5800 RPM. Good luck with that, I hope it works

Yeah,I had heard that the 80's could cause low speed problems. I also read that engines idle better if you run your idle mixture around 13.8 With carbs I would turn the mixture screw in until the idle just starts to slow then back it out a 1/8 turn.

 

[L31MaxExpress]

Finished up most of the little things today.

Fabricated a proper coil wire to replace the Vortec or LT1 plug wire I had on it, fixed a small oil leak on an oil cooler fitting, cleaned out the back of the van, removed those 2" OE replacement style tail pipes. I have the exhaust tucked in so well they hit the floor. Temporarily put those 2.5" turn downs I had when I first layed the system out on the floor on it. I modified the stock small block air cleaner, deleted the thermac flap, removed the semi circular baffle, and punched a hole through it for the IAT sensor. I worked more on the harness and have very little left to loom up and finish routing on it. I do need to drill a hole through the floor to relocate the Proflow ECU still. Very minor things left. About to finish up a few things, throw the engine cover on it and take it for a drive.

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[L31MaxExpress]

Cruised it around a bit. This 350 is an absolute animal. It comes on strong even in 3rd gear at 70 mph. I checked the speed using the PF4s GPs speedo, the van speedo is about 4 mph fast at 70 mph. 70 mph GPS is actually 2,750 rpm. I do not have the downshift solenoid hooked up yet, so it is a bit reluctant to downshift without manually shifting it down. I jumped on it from a stop and the right rear tire did not hook until 55 mph, even though it was accelerating like a beast, it was easy to feel the spin plus had a nice smell of burned rubber drift inside. Given the huge weight difference this combination would easily eat the 383 in the 97.

 

[Supercharged111]

Cruised it around a bit. This 350 is an absolute animal. It comes on strong even in 3rd gear at 70 mph. I checked the speed using the PF4s GPs speedo, the van speedo is about 4 mph fast at 70 mph. 70 mph GPS is actually 2,750 rpm. I do not have the downshift solenoid hooked up yet, so it is a bit reluctant to downshift without manually shifting it down. I jumped on it from a stop and the right rear tire did not hook until 55 mph, even though it was accelerating like a beast, it was easy to feel the spin plus had a nice smell of burned rubber drift inside. Given the huge weight difference this combination would easily eat the 383 in the 97.

Line 'em up and shoot a video, let's see it.

 

[L31MaxExpress]

Line 'em up and shoot a video, let's see it.

Lol

Still have to pull the 4L85E in the 97 to fix the fluid leak. Now that this 87 is up and running time to get on that.

 

[L31MaxExpress]

I put 10 gallons in it with the fuel gauge in the orange low fuel band bringing it straight up to 1/2 tank. Beat the snot out of it for ~15 miles and fuel level dropped a needle width, lol. Nice to have a GM of this era with a functioning gas gauge. When I put the 93 octane in the tank, I bumped the timing to 16* initial and 34* total at 3,600 which really woke it up. At 70 mph on the highway was cruising at about 40* timing at 2,750 rpm and pulling good manifold vacuum with the air/fuel dancing around 14.7:1. Judging by injector duty cycle to run 12.5:1 at WOT with the 29# injectors, this L31 is probably making more HP/TQ than the L31 I had in the 97 with the Lunati Hotcam and marine manifold. I raised the rev-limiter to 5,800 rpm too, TH400 will now make a WOT 1-2 shift without lifting. I did not happen to notice exactly where it shifted and forgot to screen capture the drive in the PF4 app, but it is somewhere between 5,500 and 5,800 as it was hitting the limiter before and does not now. When I glanced at the app, it was at 77% duty cycle, around 12.5:1 and about 5,400-5,500 rpm. 29 x 8 / 0.45 x 0.77 = 396 hp. Given the way it runs, I would believe it. I did notice at highway cruising speeds the long term fuel trims were glowing red on the app, reading -30% on the fuel delivery. I picked the Base MAP off idle vacuum which corresponds to stock cam and 350 CID displacement, not sure why they have it so rich. I will remember to screen capture the next drive and review it. If it is that rich globally, may stick a Base MAP for a smaller cubic inch engine into it so that the ECU is not self-correcting as much.

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