91dime

I am building a engine for my 89 K2500 that’s my occasional daily driver that I would like to be able tow if needed to. I bought a nv4500 for it and am going to rebuild a l31 for it.
I am going to bump the compression a little, get a truck/tow cam and possibly do long tube headers.

I am stuck on what to go with for fueling. I’ve read a few threads comparing a “ez efi” type system to a stock tpi but they are all years old. I have done a few carb to megasquirt installs so I understand what and how to do everything. I’d just like to get some opinions from say someone who made the change from tpi to ez efi and if it was worth it.

I am considering buying a complete tpi setup from the classifieds on here for the truck. I was planning on dropping it on the engine and going with it for now. I’ve never burned chips before but I am open to playing with the stock ecu after its on the road.

My question, should I ditch the tpi idea and go with a ez type system? Or get the tpi and learn how to modify it?

I also have a complete 747 system on the shelf I can play with , I saw the sticky on re pinning them. I would be ok with doing that and maybe a hsr? I really just want to keep it simple.

sorry for the rant. Any opinions?

Fast355

iTrader: (2)

Big block throttle body on a carb intake with an adapter plate.

91dime

Its a larger cfm throttle body isn’t it? The injectors are larger too? Will using them with the 5.7 ecu be a problem?

Fast355

iTrader: (2)

It has larger TBI bores and larger injectors. More CFM and more fuel. It is not a problem to run it after tuning the ECM. A high rise carb intake also flows alot better than anything built specifically for TBI. Peformer RPM with a 454 TBI unit will breath alot better than any stock runner TPI system as well.

Vader

What is the final gear ratio of the truck going to be? That answer may help to decide. It's pretty tough to find anything with a flatter torque curve than a TPI below 3,000 RPM, unless it's a diesel. .

91dime

Ok, so stick with a dual plane intake? I need to do more research on tuning the ecm, I’d really like to do it myself because I would bet it’s going to take more than one try. I will dig through the tbi section for those answers. Thanks for the reply!

91dime

It has 4.11s and searching on Novak’s site I came across this about the NV4500 transmission .

I went with the 5 speed rather than the much more affordable 4 to help with the low gearing.

The TPI shines to 4500rpm doesn’t it? That’s why I considered going that route, I’d like to keep the peak torque a little below that. I really don’t want to get into megasquirt or chip burning with this project at the moment, but I will if I need to. I kind of figured that I would need to go with a MAF system rather than SD. A stock MAF system will be more accepting to changes like cam, compression and headers right?

Fast355

iTrader: (2)

The TPI is actually fairly peaky around peak torque. A dual plane intake has a flatter torque cuve especially off-idle and under 2,500 rpm.

I am running a port fuel injected marine dual plane on the 383 in my Express van I tow my travel trailer with. 4L85E with a 5.13 geared 10.5" 14-bolt in it.

I am using an 0411 with EFI Connection 24x coil on plug ignition. It cost more money than the OBD1 stuff but worth it.

Fast355

iTrader: (2)

Just to give you an idea of what a small cam, 350 Vortec with a dual plane intake and headers will do.

https://www.google.com/amp/s/www.hot...ock-chevy/amp/

I had a set of 906 castings I had cleaned up, 2.02/1.60 valves, screw in-studs and guideplates and put them on a L31. With the little marine cam and 1.7 full roller rockers. Used the cross ram port injection L31 marine intake (basically a L31 truck intake with a cast iron base, aluminum plenum and external injectors) along with Thorley tri-y headers. On 91 octane it made 257 rwhp and 310 rwtq through a 4L85E and 9.5" 14-bolt. TQ peaked at 3,100 rpm and HP peaked at 4,900. It was over 300 rwtq from 2,700 rpm to 4,500 rpm. On E85 with the timing cranked up 2-6° from the best 91 tune it made 330 rwtq and 272 rwhp. Over 300 rwtq from 2,200 rpm to 4,700 rpm.

Fast355

iTrader: (2)

With 1.7 rockers the little marine cam degreed out right at 200/210 @ 0.050. 0.488/0.511 lift. 109 LSA and its advanced 3* on a 106 ICL out of the box. Its a little small for my taste but it does extremely well in the low-midrange especially with a higher ratio rocker.

This is what it ran like on 91 octane. Pulling around a 6,200 lbs van with a 3.73 gear and 30.5" tall tire. I was shifting it at 5,100 rpm because that is about the highest it wanted to comfortably make power to.

91dime

That’s impressive for something that weights that much. So that is a marine cam? Is that something you have to purchase through the dealership? Currently I plan to contact the cam manufacture and see why they recommend, but I’m sure it will just be a “tow” cam. It seems like the 1.6 rockers is a popular thing to do. I’ve never ran anything other than 1.5s, will I need to do anything special with the pistons?

I am seriously considering the eficonnection 24x setup and going with cop. I have a ms2 sitting on the shelf that I could throw in there, but it would have to be wasted spark. I put a 36-1 wheel with ms2 on my s10 and did the waster spark and it works great. I would like to try the 411 ecu and go with hptuners, it would be nice to learn that system for future projects. In a retrofit application how would I do the obd2? Can I do the 411 in a stand-alone setup and have the obd2 to connect the hp tuners to?

Did you use hp tuners? If so how much did you have in it?

91dime

Also, do you feel comfortable towing with the 350? Everyone around here uses diesels, but we are in an area with very steep grades so I am kinda concerned how the small block will work.

Fast355

iTrader: (2)

The marine cam was recycled into both the GM Ramjet and the HT383. Part number ending in 395'. With 1.6 rockers you should drill out the pushrod holes in the heads with a 1/2" drill bit. No piston modifications necessary. Just be sure to get the self-aligning rockers if you do not have guideplates.

I have HPTuners and Tunercats OBD2. I have had HPTuners going on 10 years now. At the time it was about $650 with 8 GM credits. Enough to tune 4 normal PCMs. I consider both of those tools. I have street tuned something in the neighborhood of 100 vehicles now. With the credits costing $100 to vin license and me charging $250 for a street tune it can be quite lucrative.

Fast355

iTrader: (2)

On steeper grades you will rev the small block a bit but it handled my trailer pretty well. When it was 3.73 geared a 6-8% grade would put it in 2nd gear at 4,500 rpm. With the 5.13 gears it would climb the same grade in 3rd at 3,500 rpm. The lower gears made it accelerate from a stop with weight, especially uphill ALOT better.

In normal driving without a trailer you will probably end up starting off in 2nd gear with the NV4500.

4L85E has the following ratios.

1st = 2.48
2nd = 1.48
3rd = 1.00
4th = 0.75

I was running a stock GM 4.3 Van torque converter. It stalled about 2,400 rpm behind the 395' cammed L31. It has a dual stator setup with the STR around 2.2:1.

My travel trailer is roughly the equivalent of towing a parachute behind you as well. 10' tall and 8' wide.

91dime

So I have been thinking about this, and taking into account what you have told me Fast355 and am still
kind of on the edge. I really don’t want to drop roughly 1k into a eficonnection kit, coils and megasquirt or hptuners right at this moment.

So I am going to research this because I know it’s been beaten to death but I am considering these

Stock 5.7 TBI
Vs
Stock SD TPI

I like the idea of TPI because of the ease of modifications. I can pick up a complete setup for pretty cheap too. The big block TB would be nice, but I would have some cash(not alot) in the gear to tune it myself.

thtanner

iTrader: (1)

MAF TPI is good stuff running on 6E. Less picky about airflow changes than SD.

91dime

That was my initial plan, but I’ve read that they are kinda slow because of their resolution? I only say that because I have read it. A local guy will sell me a complete setup with the distributor and MAF for $275. Is that a good price?

thtanner

iTrader: (1)

The very early MAF ECMs are slow, the later ones are better. I'd go with an 89 MAF setup. No cold start injector.

275 for the whole TPI setup and harness and all isn't bad. What year is it from? Even some years with a cold start can be upgraded to 89 code.

91dime

Its from an 88 Vette, they are usually a year ahead of f bodies on stuff aren’t they? I really don’t want to mess with having that 9th injector, I honestly don’t even know where that injector is at.

I plan to run 9.7:1 compression, a “mid range” type cam, and headers. Will a SD system give me that many fits with those changes?

I’ve never searched for it before, but I do have a megasquirt 2 v3.57. Can I get an “adapter” to plug it into the stock harness?

thtanner

iTrader: (1)

88 has a cold start injector but removal is a simple block off plate and PROM change newer programming. Tuned Performance in my signature can get you a prom setup specificity for your changes too.