hog

Are you sure about that 6700 rpm rev limit with the L31 1996-02 rev limit?? All the tuners in North america can only raise the stock 5600 rpm rev limiter up 200 rpm to 5800 rpm.

are you sure you are revving over 5800 rpm using an L31 Vortec 350 PCM with a Vortec V8??

please respond.

peace
Hog

GoodmanPerformance

I have the feeling that some dought what I am accomplished with my manifold and injection. People are more concerned that my message said my design could flow enough air to support 6700 RPM. Edelbrocks intake that I used to build my injection has a powerband from 1500-6700 as they claim. Keep in mind that this is a truck and not a 347 powered Ford Mustang. Its low end torque is more important than being able rev it to 10,000 RPM. Lets be realistic for a second. I not a high school kid and know how to build a fast truck.I've used a cam thats power band is 1500- 6500 in a 350, not a 383. With my 383 my power curve starts earlyer so I don't have to rev the ***** out of it. I dont have a After market tach in my truck because I dont want to mess up my factory looking interior but I know it turns over 6000 rpm. Thats up to Ed Wright at Fast Chips. I will have more soon because im making some changes on the truck and then im going back to fast chips to finish what Ive started with my fuel injection design.I will prove my design is simple and very effective and have dyno sheets to prove what it is capable of.Its simply works and looks better than the factory design or something that came on a late 90s boat. Jon Goodman

hog

I have no doubt in what you have accomplished, the same thing has been done in the V6 Vortec engines with an Edelbrock carb intake, also a Ramjet intake cut down to fit a V6 has been done.
Putting together a Vortec L31 iinjection system is really cool, our Marine Intake team looked at this, but the Marine Intake is much cheaper to put together, plus it was engineered TOGETHER, not a collection of parts from ather applications. I am not knocking your project, its really cool, the L31 needs some different intake thats for sure. The restrictive stock intake manifold is 1 problem, the other problem is the small 19 lb/hr poppet style injectors the truck intake uses.

No one mentioned ANYTHING about flowing enough air for 6700 rpm, the question is will the PCM allow for 6700 rpm?? It will not. Once 5800 rpm is reached the injector pulsewidth goes to zero, no matter where the rev limiter is set in the PCM calibration.
Your stock tach should go to 6000 rpm, get a scanner to read higher, the stock PCM tune rev limits at 5600 rpm, if you set the PCM rev limiter to ANYTHING higher than 5800 rpm, 5800 rpm is where the injector pulsewidth goes to zero, until the revs go down then the injectors start up again.

What I was questioning is your PCM tuning's ability to rev over 5800 rpm, there are LOTS of people who want to be able to rev over 5800 rpm, using your intake setup on a NA 350 without being able to rev over 5800 rpm seems kind of limiting HP wise. Sure you will gain some power with just your intake manifold, but it wont be night and day.

The real gains come by way of using the larger injectors in your intake by: allowing more cubic inches and wilder cams(but both are limited by rpm so far), allowing the proper fueling of turbo/supercharging and dry nitrous systems. With the stock 19 lb/hr poppet L31 truck Vortec 350 injectors, 400 crank hp or about 330 rwhp was the limit fuel wise. This was accomplished on a Vortec 350 with the stock intake and injectors, Vortec heads(pocket ported), GM LT4 Hotcam, headers and bolt ons.

I think you are misunderstanding me, the problem is with the L31 Vortec 350 PCM, I have spoken to many of the popular PCm tuners in North America including Ed Wright. I and other Vortec 350 guys have asked Ed to set the rev limits in our trucks to 6100 rpm or 6500 rpm. When we get our PCM's back we are never able to rev over 5800 rpm. Allen Nelson of Nelsons is also running into the same problem. I have bough the Tunercat OBD2 software, which is the only software that is currently available for the 1996-2000 Vortec 305, 350 (L30,L31). Even when I and others set the rev limiter table to 6500 rpm or 7200 rpm we still get a 5800 rpm limit. The stock rev limit is 5600 by the way.

The problem is some sort of secondary rev limit that is coming into play. The whole point of us doing the Marine Intake Manifold is to be able to use larger fuel injectors for superchargers and turbochargers. For us NA guys we need to be able to rev in order to make HP, currently we cant rev over 5800 rpm.

Ed Wright "SAYS" he can set a rev limit top whatever he wants, but in reality he cant, this has been proven time and time again in the Vortec 350, whatever we order, it keeps coming back with a 5800 rpm rev limit.

The Marine intake looks very much like the stock L31 truck intake, 1 thing your are forgetting though is that all of the poppet injectors, FPR and fuel feed lines are not inside the intake anymore, I have gotten some nice gains from the Marine intake alone. Ther is much more unobstructed plenum volume in teh Marine Intake than in teh L31 truck intake, both teh MArine and L31 truck intake have 8" intake runners.
Since the L31 currently cant be revved over 5800 rpm( to me and about 10 other L31 owners who are looking to rev over 5800 rpm) ANY L31 intake manifold's primary use is to use larger than 19 lb/hr fuel injectors for Forced Induction or Dry nitrous setups. Using the Marine Intake for NA 350 power increase is a waste of money, the gains seen from a carb intake, a Ramjet intake or a Marine intake cant be justified for the large cost involved. A complete Marine Intake conversion can be completed for under $1000US, thats not worth 10-20 hp the manifold alone will give, but if you are super/turbo charged or using a dry nitrous system, this is not that bad since it will allow you to fuel the vortec 350 without using a 9th and/or 10th injector when under boost, using supplemental injectors has very uneven fuel distribution cylinder to cylinder, having a true MPFI setup like the Marine Intake, Ramjet, or your carb manifold conversion is superior by far, plus there is no fuel flowing in an intake meant only for air.

http://www.sfatek.com/images/efi.jpg
This intake looks very similar to the L31 truck intake from the outside, but inside there is a marked difference, the truck intake is very hilly and bumpy, the floor of the marine intake is perfectly flat, the runners of teh marine intake are slightly larger than the L31 truck intake as well. The supercharged guys in our test group are reporting major power and torque gains. I personally have reported much better high rpm power even without tuning, the only tuning was to input the new 28 lb/hr flow rating of the injectors.

This intake was engineered for use on the Mercruiser 350 5.7L and 377/383 6.2L Vortec V8 marine engines, it is still available NEW today from Mercrusier and GM Marine on the same 5.7 and 6.2L engines. You can get the same exact Mercruiser/GM Vortec Marine Intake on a 2006 Donzi boat as well as others. Its not like the Marine Intake is old news in the marine world, in the truck world it is BRAND new.

I dont see how you can know your intake performs better when you havent even tested it yet??
So far there are 4 Marine Intakes installed in our little test group, 1 on a NA 383, 1 on my NA 350, and 2 more on a Whipple Supercharged Vortec 350's, both with Edelbrock ETEC 200 heads. The guys involved in our Marine Intake project have been researching this project for many years, now with teh release of Tunercat OBD2 to tune the L31 Vortec 350 PCM and a newly found supply of affordable Marine Intakes, this project was undertaken, our 1st conversion was finished early last Summer on the NA 383 with a 230/245 duration at .050" cam, as you can see, we need more than 5800 rpm.

Jon it would have been nice if you added you Edelbrock manifold L31 injection on a stock L31 engine with stock cam and heads, then we can know exactly what the manifold itself will gain, we have a few folks that have baselined before the marine intake and will dyno after, with no other changes. No matter what intake anyone puts on an engine, there is only so much to be gained from and intake change.

Even with your 383, which by the way is only 33 cubes total or 4.1 cubic inches per cylinder larger than a 350 engine is. Sure the power band would be lower down in the rpm band, but not THAT much.
No body wants to rev 10,000 rpm, but 6500 rpm would be nice, the GEN 3/4 LS1, LM7,LR4, LQ9,LQ4 crowd are in that range roughly, and these trucks are even heavier than ours, so the desire to rev over 5800 rpm is surely a valid desire. It is VERY VERY realistic to want 6000 + rpm on a performance truck engine. A NA smallblock HIGH-PERFORMANCE engine that doesnt spin over 5800 rpm isnt really that wild of an engine, kinda tame really. Torque is great for towing, but most people doing an intake swap WONT be doing it for towing purposes, they will want mid-high rpm power and torque for performance. If low rpm isnt the greatest, a higher stall TC can be added, just like you did in your truck. With the 2800 rpm TC in your truck, low rpm torque wont be an issue at all.

I have my 1/4 mile timeslips from just before the swap, in late March early April I will have my after timeslips.

The MArine Intakes are a solid way to fuel a Vortec 350. The stock L31 throttlebody, cruise control, distributer and air intakes can ALL be used. Nobody is making fun of your idea, why poke at ours??? Esp when you dont have any proof to back up your claims. I guess the proof will be in the pudding.

I salute your efforts, I can hardly wait to see some pictures of your setup, and to see your dyno results, the more different intakes we can get for the L31's, the more quick and fast L31's can be built. We have been stuck with a restrictive and under fuel intake for too long, finally we can breath and add enough fuel to the fire.
Congrats Jon, goodwork, I am glad that there is yet someone else out there trying to do things with the Vortec 350 that hasnt been done before.

peace
Hog

hellbents10

iTrader: (10)

Hog, I have a way tro raise the rev-limiter!!!! Send me your file.

hog

Right on, will so.
thanks
peace
Hog

litreddevil

iTrader: (4)

there r also guys putting the 02 pcm in the old body style motors they r just getting what pin gose where and then retuneing it so for i know the truck is running go.and no problems

hog

I though about doing this also, but was told that there are differences in the crank position sensor among other things.

The L31 Vortec 350 was used into 2002 in the fullsize vans and into 2005 in some of the 4500 series commercial trucks.

the 4.3 V6 is also being controlled by the newer PCm's even though its an older style engine.

do you have any specifics about the newer PCM's being used in the older style truck 96-99 trucks??

Any info would be greatly appreciated. Thanks man.

peace
Hog

350SS

iTrader: (36)

Hey Hog,

I think that you're referring to my comments that I made in another thread about the difference in crank and cam sensor outputs, etc... I hope someone can elaborate on the 02 pcm swap into our trucks. If they used an 02 pcm (or any other year for that matter) to control a 5.7l gen I style engine in vans or whatever, I'm sure it could be used to control the engines in our 96-98 trucks. My questions are: is it the same pcm as used in 2002 trucks w/ Gen III motors? What operating system does this pcm use and is it supported by HP Tuners or EFI Live? Personally, I don't think it would be the same pcm or OS. I don't think that the same os would be able to interpret the difference between, for example, a 4x/rev vs. a 24x/rev crank signal. I hope that I'm wrong because that would mean I could use EfiLIve to tune my truck, which I'm going to be using in my chevelle anyways! Please someone post details on this pcm swap like part numbers for the pcm you're using, operating system number, tuning software being used, etc...

Max