The stock 5.7 is getting a little long in the tooth. I've been contemplating what kind of swap I'll do... I'm looking for something that's fun to play around with around town, but that's quite reliable. I also want to do something a little "different" than the basic hopped up swap. I've read until my head hurts on 383 strokers and the whole marine intake thing. I was hoping to get into the 400's for displacement on the stroker... is this doable on the L31 block? Also, while I'm mechanical, I'm not a mechanic... and I've got about a zillion other projects with my other truck, house, family, whatever. So, any recommendations on a "turnkey" solution that either I could do a weekend swap on? Or, any shops in the Denver area that'd be a good place to go for the whole deal?

edit: Trans is 4L60e and got all the "goodies" done to it a few months ago when I snapped the drum. It's also got a 2300ish stall converter. I am told it's good for 450+ non-juice horsepower.

 

try Scoggin Dickey for BUNCH of options....or check out our sponsors as alot of them deal in the older motors too

 

Are you looking to do this N/A or with a power adder? As for intake, I'd recomend doing the Ramjet intake over the terrible flowing marine intake.

 

It's probably not what you're looking for as far as cubic inches but, I say ZZ383 from the GM Performance parts bin, just transfer all the "injection" stuff over. I am also not a mechanic and do not know if it is that simple, but it may be. The ZZ383 is 425hp/425ftlbs. It comes less intake and ignition, which sounds like what you need. The ram jet style intake is also a good choice. I do not know what your budget is, but I know the engine is a good one.

 

Cmon now, the marine intake is a nice step up from the stock L31 intake.

What experience with the marine intake do you have to be able to make such a strong statement such as that???

The marine intake has slightly larger runners than the stock L31 intake, has ZERO internal obstructions. There are guys making serious hp with the marine intake now.
The Ramjet makes some more power, but who wants to pay that much money????
The cross ram Marine intake was designed for both 350 and 383 (6.2L) marine engines, its a very nice alternative to the stock L31 truck intake. The truck intake limits power to 400 at the crank due to its 19 lb/hr poppets and severe internal obstruction and lack of plenum volume.
The marine intake is an easier swap than teh Ramjet, no linkage adjustments, stock crusie control works and would pass a visual inpection before the Ramjet would. I do realize that in Michigan there is no smog checks, but there are in other places.

Not putting the Ramjet down at all, its a decent stock intake. It was designed for 350 hp on the Ramjet 350, which is just a 1.6:1 roller rockered, mildly cammed L31 engine. The marine intake is placed on engines that spec the same power all mods equal.

Anyone could get an easy 400 hp on a 383 with iron Vortec heads with the marine intake, 425 with the perfect cam and exhaust. The swap isnt very difficult, I did my conversion for less than $1000 including tuning.

You wouldnt be able to properly fuel a ZZ383 with the stock intake, but with the Ramjet, Marine or converted vortec carb intake manifold you would easily be able to fuel it.

Well, lets hear it? It sounds like you have flowbenched or dynoed these intakes.
I am a glutton for test data, thanks in advance Zippy.
peace
Hog

 

I had always thought that the ram jet was a much better manifold, but I didnt really know to be honest. I would have thought that the ram jet was capable of much more power then the marine L31 was. Is there any other manifold That is worth bringing into the equasion that could be used fairly easily with the vortec heads? I like to explore all my options. Also, how hard is it to track down a marine manifold for these engines? All tuned and everything for about $1000 is def. worth checking out.

-Rob

 

Any Vortec carb intake that is drilled for injectors will work and would outflow both the Ramjet and the MArine intake.

I agree, the ramjet intake will make more hp than the marine intake, but to say the marine intakes flow is HORRIBLE simply isnt accurate


There is a guy on the PPE truck forum that gets them and sells them as a kit. The kit comes with GM colour coded injector wiring, injector connectors, injectors, fuel rails, and a lot of otherstuff. All I needed was fuel connections, intake gaskets and a tune(change the IFR).

The marine intake "appears" to be the same as the stock truck intake from the outside, inside they are very different.

Next time I have my marine intake off, I will cc it along with the stocker. There will be a sizable difference I guarentee it.

With the Ramjet incomming air must take a 90° turn downwards, in the marine intake the air travels straight down into the intake runners.


ANYTHING is better than the stocker. A stock marine intake would certainly ouitpower a stock TPI intake manifold, but that isnt saying much at all.

When takingthe height of the Ramjet intake into account I bet the intake runner length is very close to the cross ram design of the marine intake.

I wish I had a side by side pic of an open marine intake and an open stock truck intake, the difference is substantial.

peace
Hog

 

Thats interesting... so if you were going to make a serious power house fuelie 350 what route would you go in for the injection/intake manifold. I am still pretty new to this and am just exploring all of my options. The ram jet claims to flow 1000 cfm which seems like a ton even compared to the manifolds and carbs on the performance 383 packages from GMPP. How hard would it be to make one of those carb style manifolds work with the vortec computer?
I found one on ebay that looks pretty cool, but it i spretty expensive... you be the judge!
Sweet Manifold

Is it a piece of Manifold? or will that baby make some serious power?

I'm really surprised to hear this about the ramjet manifold... its numbers seem impressive enough. I always wondered why they didnt throw one of those on a 383 application to make a fuelie 383 powerhouse.

-Rob Nap

 

Next time you're at your local dealer's retail parts department, pick up the 2006 GM Performance Parts catalog...last time I went in to try and get some exhaust manifold bolts, the dealer I was at had the catalog for 5 bucks ($5.30 with tax). The cover picture is a copper/orange 70 Chevelle with a 572 under the hood I might have to go out and get another catalog as the one I have now is soaked with drool

 

That intake would make some serious power, its a single plane intake manifold. That woudl work awesome on a Vortec 350 engine. It wouldnt be TOO hard to make work in an L31 truck.

On teh flow, just remember that carbs may be flowed with air and fuel, whicl ethe Ramjet will not be flowed with fuel in the air at all.

Where did you hear that the Ramjet flowed 1000cfm??? Thats just an LS1 throttle body on the front of it and I doubt that 78mm t-body flows 1000cfm.

I think that Sallee actually did make a RAmjet 383. It had teh aluminum 210cc intake port Fastburn heads with a Ramjet intake. It was rated at 450hp IIRC.

If you want to make serious power with Vortec heads, these intake manifolds arent goingtio be limiting factor, the heads will be IMO. If you want to stay Vortec either GMPP FAstburn or Edelbrock Etec 200's or GMPP Bowtie Voretc largeport Iron heads out will be needed, for max results a nice port job would be nice.

peace
Hog