New Engine Help

**Engine07** · 01-29-2015

My list of plans for getting my truck back to new are still progressing, lol. I am getting about ready to start the new engine in the next few months. Gathering parts already. I am unsure of the exact horsepower of a build this style but am looking for input on what any of the experienced tuners here think or would do differently. And also what all I will need to do to the fuel system to upgrade to run the new engine. As this truck is a daily driver I will also not be opposed to pay someone to help with the tuning. I know I'm not experienced enough to tackle the tuning alone and get it close to start lol. Engine is a 350 vortec block I have that needs bored. I am going to be .030 over and was scared if the tbi could support it bumped to 383 so if it can let me know your thoughts please as this needs to be reliable not wanting to go to carb. I'm thinking 355ci. The heads looked at are promaxx 185cc intake vortec style. Never used promaxx before so let me know what you think if you have please. Chevy magazine had them rated at 430ft lbs 408 hp on a 350 build with a cam slightly larger than I'm looking at. Cam choice is lunati hydraulic roller. Specs are Advertised Duration (Int/Exh): 279/287Duration @ .050 (Int/Exh): 213/219
Gross Valve Lift (Int/Exh): .447/.471
LSA/ICL: 112/108
Valve Lash (Int/Exh): Hyd/Hyd
RPM Range:1500-5500
Looking at 1.6 rockers to get lift to .477 intake/.502 exhaust. I contacted promaxx and was told that their heads had viton seals, 2.02 intake/1.6 exhaust and could take .575 lift and springs almost exact match to lunati recommendation. And edelbrock performer rpm intake with tbi adapter. Also looking at approx 9.5 compression with forged pistons. Any suggestions on changes you would make? If promaxx heads are any good? Hp thoughts? Where to start tuning? Fuel system changes? Bored tb or 454 tb or holley 670, etc? I have very limited experience with tbi as all of my previous builds have been carb. Thanks in advance. Also am running 95 k1500 with 4l60e, 3.42 gears. Also going to 4.10 gears soon. 7427 ECM currently using $0D.

**BLG355** · 01-30-2015

If you do a search in my name, you will find some threads that may be useful. I am working on a 95 k1500 as well, similar build. A few of the threads will address several of your questions.

Do you have any tuning equipment yet? I actually got screwed by TBIChips and came here and was very fortunate to work with one of the best tuners ever. He got me going and I bought equipment from Moates.com to be able to try things myself, which is the way to go IMO and if you want to get it really close, it's probably about the only way.

BLG

**Engine07** · 01-30-2015

I have the tuning equipment just not the knowledge of what all to change yet lol. I'll keep searching around. Thanks. I talked to tbichips and after reading some stuff by Dave and eaglemark I decided the knowledge base was great here and decided better off to do it on my own with some help

**Engine07** · 02-03-2015

My best guess is somewhere around 340-350hp potential from this combo with the tbi. All of the calculations I'm coming up with are either leaning towards 454 injectors around 16-17psi or 350 injectors around 30psi. What would be your recommendation? Can the 454 injectors be reduced enough in the tuning that I will be fine with them at an idle if I go adjustable regulator and up them to 17? Sry for all the questions I have been trying to research and seem to come up with a lot of mixed stories.

**BLG355** · 02-03-2015

I am currently running 22psi on 5.7 injectors and i can't go as high in RPM's as i would like, i think the injectors are going static, it goes lean. I am also looking to do 7.4 injectors. My plan is to try 7.4 injectors at 15-16 psi, instead of running higher pressure on smaller injectors. I had my 5.7 injectors at 30psi and it seemed fine, but i was worried about reliability. From what I've read, it can actually be harder to tune with higher fuel pressure, or using a vacuum referenced regulator of sorts. I want to avoid that if I can. According to Desktop Dyno, mine is around 320-340hp and 440ft/lbs, or close to that, I can't remember the exact numbers. I modified my regulator to adjust it, it's fairly easy to do. I think the 7.4 injectors are the way to go.

BLG

**Engine07** · 02-04-2015

Thanks a lot. Sounds like we will have almost identical builds lol. I don't have computer dyno just guessing from what I've built in the past with carbs. Thanks for the advice. Looks like I'll be using ported throttle body, adjustable reg, injector spacer, and 7.4 injectors. My thought was originally using a performer rpm intake with adapter but from what I have read there seems to be big controversy over single plane not losing torque at lower rpm with tbi like it does with carb. Any thoughts or suggestions? Looks like fast355 was running a victor jr 2bbl intake with good success on tbi without losing low end torque?

**brian617** · 02-04-2015

Something to think about is heating the intake with coolant for driveability. I understand the Performer RPM can be water heated, however that single plane victor can't.

**BLG355** · 02-04-2015

My main goal was to maximize performance, without losing any drivability. I wanted it to remain as calm as possible but still run strong. I used a Edelbrock 3704,which I bored out to accept the 2" bores on the 7.4 throttle body. Here in PA I need it to pass a visual emissions test. The 3704 let me do that. Other than that intake, I'd go for any good dual plane. A Torker 2 is supposed to be the best of both worlds, kind of like the Weiand Stealth intakes. I had one on a 305 carb engine years ago and it was fine. Everyone will have their favorite and what worked for them so it makes it tough to decide, especially when there are so many choices.

BLG

**Engine07** · 02-04-2015

That's true Brian. That eliminates that. I'll prob stick with the performer. I'm more after low end torque.

**Fast355** · 02-04-2015

Originally Posted by BLG355

I am currently running 22psi on 5.7 injectors and i can't go as high in RPM's as i would like, i think the injectors are going static, it goes lean. I am also looking to do 7.4 injectors. My plan is to try 7.4 injectors at 15-16 psi, instead of running higher pressure on smaller injectors. I had my 5.7 injectors at 30psi and it seemed fine, but i was worried about reliability. From what I've read, it can actually be harder to tune with higher fuel pressure, or using a vacuum referenced regulator of sorts. I want to avoid that if I can. According to Desktop Dyno, mine is around 320-340hp and 440ft/lbs, or close to that, I can't remember the exact numbers. I modified my regulator to adjust it, it's fairly easy to do. I think the 7.4 injectors are the way to go.

BLG

I have a Marine 502 throttle body that has 61# injectors and a 30 psi regulator. They have a different part number and color code than the 5.7 61# injectors but seemed to not have a problem with the pressure.

**Roadknee** · 02-04-2015

Theres nothing wrong with 383 TBI. It will build about 40 more ft-lbs than a comparable 355. I considered one for my 1995 K1500. I'm sticking with the 350 due to concerns of the 4L60e holding up in a heavy truck.

If you're truly after low end torque, I'd look into smaller heads and cam. What you've selected would pull strong to 6k, but give up a lot below 2,500 rpm, particularly at part throttle. I think it would be pretty weak on the highway in OD with the torque converter locked.

For heads, I'd recommend what BLG or Brian are running, or a set of OEM vortecs. I think BLG's cam is a winner for a truck, and will pull strong to 5,200 or so while still making good torque. The GM cam in Brians motor is a good one too. It runs better than you would think for its size. It would build more bottom end than BLG's, but fall off about 400 rpm sooner. For a truck with OD, I'd recommend no more than 260 duration at 0.006" and 206 at 0.050 on the intake. A little added exhaust duration will help extend the HP peak, but will hurt low speed torque and part throttle fuel economy.

I've helped 355chev on this site tune the vortec 355 tbi in his 1995 K1500. It's running vortec heads, 10:1 compression, bored TBI, 5.7 injectors, 28 psi, performer manifold, headers, a 260 Comp Cams xtreme 4x4 hydraulic roller with 210 @ 0.050 intake duration. This cam has very aggressive lobes with over 130° @ 0.200". It pulls really strong, making about 320-330 hp at 5,200 rpm. Part throttle torque is a little weak requiring we delay locking the torque converter till 60 mph.

**Engine07** · 02-04-2015

After looking a little more into the heads and seeing some of the work that has come out from there I'm changing up on the heads too, lol. Saw pics from one guy of brand new heads not installed yet held a flashlight under the combustion chamber and took a picture down the ports of all the light you could see making it through a non concentric valve. Going to just get a set of scroggin dickey or use the set of 906's I have in the shop. Was saving them for another build since they need redone but I have the tools just gotta make time. Prob just mill flat the stud holes and tap them, cut down the valve guide bosses, and put in new valve guides and valves. On the 4l60e though they can be a really tough trans (to an extent) if put together properly. I wouldn't trust a factory one to hold up at that torque in a heavy truck for to long but with a few modifications you can.

**Fast355** · 02-04-2015

Originally Posted by Roadknee

Theres nothing wrong with 383 TBI. It will build about 40 more ft-lbs than a comparable 355. I considered one for my 1995 K1500. I'm sticking with the 350 due to concerns of the 4L60e holding up in a heavy truck.

If you're truly after low end torque, I'd look into smaller heads and cam. What you've selected would pull strong to 6k, but give up a lot below 2,500 rpm, particularly at part throttle. I think it would be pretty weak on the highway in OD with the torque converter locked.

For heads, I'd recommend what BLG or Brian are running, or a set of OEM vortecs. I think BLG's cam is a winner for a truck, and will pull strong to 5,200 or so while still making good torque. The GM cam in Brians motor is a good one too. It runs better than you would think for its size. It would build more bottom end than BLG's, but fall off about 400 rpm sooner. For a truck with OD, I'd recommend no more than 260 duration at 0.006" and 206 at 0.050 on the intake. A little added exhaust duration will help extend the HP peak, but will hurt low speed torque and part throttle fuel economy.

I've helped 355chev on this site tune the vortec 355 tbi in his 1995 K1500. It's running vortec heads, 10:1 compression, bored TBI, 5.7 injectors, 28 psi, performer manifold, headers, a 260 Comp Cams xtreme 4x4 hydraulic roller with 210 @ 0.050 intake duration. This cam has very aggressive lobes with over 130° @ 0.200". It pulls really strong, making about 320-330 hp at 5,200 rpm. Part throttle torque is a little weak requiring we delay locking the torque converter till 60 mph.

The cam he spec'd is smaller than the one I would run. If that small cam is weak down low its because its not running enough timing or the fueling is off. I am running 215/220 @ .050 with 170cc ETec heads. I have my transmission paramaters set to keep me over 1,200 rpm. With 3.73s and the 4L80E at light throttle I am locked up in overdrive by 45 mph and the 350 has no issues pulling around my 6,200 lbs Express conversion van.

I put a pair of those $685.00 Promax heads on an otherwise stock Tahoe that had a valve guide issue and it ran very strong.

**Engine07** · 02-05-2015

Good to know!! I guess quality was good on yours? Maybe that set was just a fluke. Any idea how many miles you have put on them? Hoping everything goes good and I get plenty of time this weekend. Got my gears ordered today so maybe I'll have time to put them in this weekend

**Fast355** · 02-05-2015

Originally Posted by Engine07

Good to know!! I guess quality was good on yours? Maybe that set was just a fluke. Any idea how many miles you have put on them? Hoping everything goes good and I get plenty of time this weekend. Got my gears ordered today so maybe I'll have time to put them in this weekend

Not alot of miles yet on it, but the ones I had seemed decent on quality. If you have a set of rebuildable stock heads they can work quite well too. The canadian 906s seem to flow better and the Hecho en Mexico 062s the worst.