$EE / LT1 Injector Swap Running Rich

**spfautsch** · 07-31-2017

I'm happy to see someone else building a standard displacement LT-1. I've always preferred building a smallblock that puts the fat part of the power band over 5000 rpm. As long as your rod bolts are decent, your rod bearing clearance isn't over 2 thousands and your valvetrain will handle it, a moderately built 350 with a nodular iron crank will happily produce good power at 7000 rpm all day long. What's your rev limit set at, and have you hit it yet?

I've yet to get my warm start "perfect", but have been distracted by numerous other things wanting tweaks. It is firing immediately and running without having to crank a long time (or a second time) now, but doesn't quite breathe to life as it did with the factory injectors + tune. Even if I can't get it perfect I'm happy not to have to pedal it to clear the flood.

**Aroberson77** · 07-31-2017

Originally Posted by spfautsch

I'm happy to see someone else building a standard displacement LT-1. I've always preferred building a smallblock that puts the fat part of the power band over 5000 rpm. As long as your rod bolts are decent, your rod bearing clearance isn't over 2 thousands and your valvetrain will handle it, a moderately built 350 with a nodular iron crank will happily produce good power at 7000 rpm all day long. What's your rev limit set at, and have you hit it yet?

I've yet to get my warm start "perfect", but have been distracted by numerous other things wanting tweaks. It is firing immediately and running without having to crank a long time (or a second time) now, but doesn't quite breathe to life as it did with the factory injectors + tune. Even if I can't get it perfect I'm happy not to have to pedal it to clear the flood.

I built a standard displacement LT-1 as well. where is your rev limiter at? I set mine around 6300

**Casey96SS** · 08-01-2017

Originally Posted by spfautsch

I'm happy to see someone else building a standard displacement LT-1. I've always preferred building a smallblock that puts the fat part of the power band over 5000 rpm. As long as your rod bolts are decent, your rod bearing clearance isn't over 2 thousands and your valvetrain will handle it, a moderately built 350 with a nodular iron crank will happily produce good power at 7000 rpm all day long. What's your rev limit set at, and have you hit it yet?

I've yet to get my warm start "perfect", but have been distracted by numerous other things wanting tweaks. It is firing immediately and running without having to crank a long time (or a second time) now, but doesn't quite breathe to life as it did with the factory injectors + tune. Even if I can't get it perfect I'm happy not to have to pedal it to clear the flood.

I would have done a 383 but this was my first full engine build so it was a bit of a learning experience. I did not want to put the extra money into it in case I really screwed something up. It does has forged 6" Scat rods with ARP bolts and lighter Wiseco pistons. I kept the quench pretty tight. The plan was to be able to rev it to 7,000.

Currently have the rev limiter set to 6,600. Have only had it to about 6,300 so far. Only have about 500 miles on it. Working on getting the fueling a timing dialed in better before I really wind it up. Will eventually set the limiter in the 6,800 to 7,000 range when I am comfortable with how it is running. It does like to pull up top though. Looking forward to getting my 4.10 rear swapped in.

It seems the changes I made to the cranking tables really helped with hot starting. It starts about like it did stock. It fires after a couple revolutions. It could probably get better but I am much happier with it now.

**spfautsch** · 08-01-2017

I almost went 383 when I found out that it's no longer cost effective to have rods re-sized, and what speed shops are charging for crank balancing these days. But I decided I didn't want to cobble on connecting rods or the block, and the 4x3.48 bore x stroke combo is pretty well proven.

I've hit my 6800 rev limiter a couple times when the pavement was cold and it would just bake the tires off immediately above 4500 rpm. But now that the roads have warmed up I'm finding the extra revs are nice in the 1/4 because I'm able to finish in 3rd gear.

Ultimately I'd like to tear it back down and go the 6" rod + single eyebrow forged slugs route and possibly have the decks zero cut. But with what I spent on this go-round I may not have the disposable income to do that for several years.

I'm pretty much done fine tuning VE and am waiting for a GPS board to build my performance computer for tuning WOT. I may have time this weekend to do more fine tuning on hot starts. I've gotten to the point it's starting reliably but not very "enthusiastically" between 120F and 150F. Hot starts are a little less "enthusiastic" also. As I mentioned previously it seems to fire on the first full compression stroke, but instead of picking up revs exponentially like the stock tune it sort of comes up to speed over two or maybe even three revolutions. I guess I'll start working in small increments on hot start to see whether it wants more or less fuel.

**spfautsch** · 08-06-2017

I'm not sure I've gotten the start tables perfect but I did at least determine without a doubt what had me chasing my tail on this one.

The "Prime Pulse Width vs. Coolant Temp" table, along with most of the others in this category are stored as 8 bit cells which are then scaled by the mask by multiplying with a floating point constant to come up with pulsewidth. For this particular table that value is 1.5625. This leaves a fairly limited range of low pulwidth values for tuning to large injectors (minimum of 1.56, and multiples thereof - 3.13, 4.69, etc). What I was doing wrong was blindly scaling the table in TunerPro, saving the table and then saving the bin and flashing. My dumb *$$ finally caught on when I was working on hot starts last night and had added 10% to the rows between 68 and 128 ect, and eehack couldn't find any differences to write. The changed cells were getting pumped back through the conversion formula and resolution was being lost. <planting forehead firmly in palm> I suppose this begs the question - is there a way to view / edit the raw hex data in TunerPro?

So assuming I won't be able to get warm starts (around 60c) perfect, I'm weeding through the disassembly to see if I can change the floating point scalar constant used in the conversion formula. Cutting it in half should give me ample resolution to fine-tune this one table.

**dzidaV8** · 08-06-2017

You can view raw data in TunerPro, just right click on the table and select "Show raw hex".

**spfautsch** · 08-06-2017

Duh, can't believe I missed that. Need a bigger screen or bifocals.

I'm trying to find where the lookup value from this table is scaled by 1.5625, but don't speak much motorola. I think this is the call loading the table but it looks like it's multiplying (something) by 018f, which unless I'm using the wrong endianness doesn't equate to 1.5625. Edit: or is L018F identifying a memory location?

Code:

3758    B6 01 93            ldaA    l_0193_CoolTmp_fltrd_$f0_max_$e0
375B    CE 26 82            ldX    #$2682
375E    BD 78 12            call    l_7812_lkup2d_nooff_16spc
3761    F6 01 8F            ldaB    L018F
3764    3D                  mul    
3765    05                  lslD    
3766    24 02               bcc    @32
3768    86 FF               ldaA    #$FF
376A    CE 26 80        @32    ldX    #$2680
376D    BD 77 81            call    l_7781_A*X->D_8x16_Mult_sub
3770    1A 83 7D F0         cmpD    #$7DF0
3774    23 03               bls    @33
3776    CC 7D F0            ldD    #$7DF0
3779    FD 01 A1        @33    stD    L01A1
377C    B6 01 90            ldaA    l_0190_NTPSLDT_a
377F    B1 26 D9            cmpA    L26D9
3782    23 05               bls    @34
3784    CC 00 00            ldD    #$0000
3787    20 18               jr    @36