DBLTKE

iTrader: (1)

I just picked this thing up for super cheap. But I have no info on it other than it being a SBC intake. I did some quick searching and it doesn't look like any intake that in firmiliar with. There is a casting number on the back by the distributor hole: 12553917

I know it's not a miniram, it looks very similar to the GM ramjet, the the top of the intake has ribs instead of being smooth and having the ramjet logo engraved into it.

BobbyRod

It looks like a ramjet for Vortec Heads, never seen it before, brand? fabbed maybe?

TTOP350

iTrader: (8)

I'm going to guess its for a GM/Merc boat motor because the coolant jackets are coated to protect them from salt water.

abray1

Its a ramjet that is powder coated. Could have come from street and performance or a place like that that sells them and does chrome and powder coating. Has GM injectors, sensors etc.

DBLTKE

iTrader: (1)

Well it does look just a a GM Ramjet, the only weird thing is that the casting number is different than any info I find on the Ramjet. Are these intakes any good? It seems that hardly anyone has used one. How does it compare to a HSR or Miniram?

cal30_sniper

iTrader: (16)

That's a Mercruiser Marine intake (Vortec head). It's exactly the same thing as a Ramjet, just without the "Ramjet" logo on top, and includes coated water-passages and slightly different throttle body linkage. It's supposedly one heck of an intake. Imagine a Stealth Ram with a really beefed up lower-RPM torque curve. The GM Performance Ramjet 350 puts down 350 hp and an amazingly flat 350-400 ft-lb of torque curve throughout the powerband (with a 196/206 duration cam none-the-less).

I just got a complete Ramjet setup off of eBay for $450. It'll be going in my GTA on my spare L31 long block with a Comp 268XFI cam and some other goodies when I get the time to get it done. What're you planning on doing with this one?

Johnny Blaze

iTrader: (15)

What'd it take to work in place of a tpi? I like the idea of this over a stealth ram.

TransAM Joe

iTrader: (6)

Actually it's an Indmar marine intake based off ram jet lower and Indmar plenum. Great design and made great power. They are tuned pretty hot and required min 89 but really needed 91 octane to run right. These were put into high performance inboard tournament ski/wakeboard boats.

I can provide lots of info on this intake/engine as I am Indmar factory trained.

I pulled specs out of service manual and posted below


Displacement: 5.7 L/350 CID
Horsepower: 345 at prop shaft
Cylinders: V-8
Bore & Stroke: 4.00 x 3.48
Block Mfg: GM Powertrain
Compression Ratio: 9.4: 1 High-flow Vortec heads
Fuel System: GM multi-port (Indmar Plenum)

Computerized Engine *
Management System: Custom calibrated by Indmar it uses GM’s marine specific ECM computer with sealed ceramic circuit board.* Uses latest CEFI-3 software.

Ignition: Electronic, Delco HEI
Fuel Required: Unleaded, 89 octane minimum
Oil Type: SAE 15W-40 Pennzoil Marine
Max. RPM: 5200

cal30_sniper

iTrader: (16)

Whatever name you want to call it by, it's a Ramjet intake without the lettering on top. There's absolutely no practical difference between the marine version and what you can buy from GM Performance, except perhaps that the rear of the plenum is not tapped for power brake vacuum. He didn't post any photos of the rear of the intake, but the boat intakes I've seen before weren't.

Not much more than any other intake swap out there. As long as you get the complete intake with injectors, rails, throttle body, etc, all you really have to modify is the fuel lines to the rails, the throttle, cruise, and TV cable linkage, and the upper radiator hose. You'll obviously have to retune to get the full benefits of the swap, but you should be able to run it with either a MAF or SD system.

If you look for a used intake, make sure you get one that includes injector rails. They're something like $400 new, and are unique to the Ramjet. However, it uses a standard LS1 throttle body, so you can source that very easily. It'll probably be a year or two before I can get my Vortec motor ready to go in, but I've been doing a lot of reading up on the swap. I'm honestly surprised that this isn't way more popular of an installation.

Johnny Blaze

iTrader: (15)

Ok, where can we find these? Anywhere to get a good deal?

cal30_sniper

iTrader: (16)

Same places you look for everything else. Ebay is where I got mine, but they aren't too common on there.

DBLTKE

iTrader: (1)

Well this intake is designed for Vortec heads by the looks of the bolt pattern. It does not have any other vacuum ports though. I think that could be a easy fix by simply drilling and tapping the rear for a vacuum fitting. I would still like a definite, solid answer about what this intake really is. Can anyone provide any links? I've searched up on Indmar and Murcruiser and I cannot find any intake that looks like this. Even on any GM website I don't see anything about a marine version of the Ramjet.

cal30_sniper

iTrader: (16)

Do a search here on the forums for Ramjet. Some of the early work by members on the board here mention a marine version. The conclusion then was that it's identical save for the missing vacuum ports. If you don't mind drilling and tapping the rear for the power brake booster, then the marine version is a cheap way to get a really expensive intake. Only problem is they are rare, and you might get into a bidding war with somebody else that knows what it is.

Things we know:

-It is absolutely, positively, a Vortec only head.
-This is definitely a Marine Intake.
-It is dimensionally identical to the GMPP Ramjet
-It uses an LS1 throttle body and indigenous (Ramjet) fuel rails
-The throttle linkage is slightly different than the Ramjet throttle linkage
-The water-passages are coated for corrosion resistance
-It lacks the Ramjet script
-There is no Vacuum Port for Power Brakes

I could not tell you whether this intake was made by Mercruiser or Indmar, but I can tell you that Mercruiser is the only source I know of for factory OBDI fuel injection on Vortec heads. They produced a TBI-injected Vortec motor rather than switching to the new Vortec fuel injection when the Vortec heads came out in '96.

Above is fact, Below is Speculation.

It would make sense to me that they would also have produced a TPI style intake for the higher-performance boats, since they had retained TBI and OBDI even after the vortec head change.

I really see two possible trains of thought that led to the creation of this intake:

1. It was a GM test-bed that was eventually scrapped. When GM was working on the simultaneous introduction of the LS1 and Vortec Gen I SBC and Mark V Big Block, this intake could be seen as a logical experiment to keep the Vortec Gen I in lower level performance cars with a TPI. Possibly a separate design track where the TPI->LT1->LS1 branch split one way, and a TPI->T-Ram->Ramjet branch split the other way. The intake is quite similar to the LT1 Intake, but uses an LS1 style throttle body, on Vortec heads. GM Eventually decided it was cheaper to leave the Performance to the LT1/LS1, and the heavy work to the Gen I and Gen V Vortec motors, decided to begin phaseout of the Gen I SBC and Gen V BBC altogether, and the program was dropped. Indmar, or Mercruiser, got wind of the project and decided it would work great in their boats, and jumped on it. Later on, when GM Performance wants to build a low-cost EFI crate motor, they couple very cheap but powerful and available Vortec heads to the until-then-forgotten intake, and the Ramjet is born.

2. The intake is developed independently by Indmar, Mercruiser, or a third-party Marine Engine Industry, maintaining a small niche in low-cost performance boats. When GM goes looking for a new intake for their crate motor, they find it is much cheaper to purchase this design with the bugs worked out and modify it for automotive use than to develop their own.

I'm going to say that scenario #1 is much more likely. The marine industry does very little engine performance R&D of their own, relying almost entirely on the auto industry and then converting successful automotive designs for marine usage.

Either way, you've got a great setup there. Drill and tap the rear of a plenum for a Vacuum Port, figure out how to make the throttle linkage work (or just get a used LS1 throttle body), and bolt that sucker to some Vortec heads. If you're still not satisfied it's a Ramjet intake, let me know, and I'll get you some measurements directly off of mine.

-cal30sniper

jmd

iTrader: (4)

thanks for clearing up some questions before they were asked, sniper.

any pics added to the thread for comparison could only help others in the future.

cal30_sniper

iTrader: (16)

My Ramjet. It has identical casting numbers, except for the one extra code cast into the bottom of mine (my intake also has "2431" cast into it in the same place as yours, just kind of hard to see from my picture). Also note the slight differences to the throttle linkage. Mine is set up for a TV cable, LS1 style throttle cable, and has a cruise control fitting also:













Here's my casting number (off of the Ramjet intake pictured above)

Hope that helps some. This looks like an excellent intake choice over the stealth ram for us GTA/Trans Am/Firebird types. Preliminary beer can crush tests with mine indicate that there's going to be about 1/4" left between the top of the intake and the underhood padding with factory motormounts. Should be no trimming of the hood bracing required.

-cal30sniper

DBLTKE

iTrader: (1)

cal30sniper, awesome info and comparison, thank you. Does anyone know the plenum volume, runner length and flow numbers? I've started my hunt for some vortec heads but id like to match a cam as best I can, knowing those specs will make it easier to so. I'm pretty glad I jumped on the opportunity to pick this intake up. The guy I got it from had no idea what he had, he didn't even know what kind of engine it would fit so I offered to "take it off his hands."

cal30_sniper

iTrader: (16)

I'll see if I can dig up some of the threads that I bookmarked. I want to say that there was flow numbers in some of them. Check the stickies at the top of the thread, there's a few threads linked about the Ramjet. Doesn't seem like anyone has been doing anything with these recently.

The Ramjet crate motor cam is a 196/206 duration cam with .460/.481 lift (using 1.6:1 rockers). That produces 350hp/400ft-lbs of torque (that 350hp comes in at a relatively low 5200 rpm).

From what other people are reporting, the LT4 hot cam with this intake is worth 400hp. I'm looking at the 268XFI for mine. Should do everything the hot cam does but a bit smoother for daily driving.

I found this manual for the Ramjet crate motor online:
http://www.chevroletperformance.com/...Jet_Engine.pdf

Direct quote from the first page:
Answers that question, haha.

-cal30sniper

TransAM Joe

iTrader: (6)

If you want to get down to the nuts and bolts of the marine version, I would agree with cal on scenario 1, GM had the LS series ready to go and sold off some of it's engineering but if you take apart the Indmar version they have done some additional port work to the intake and plenum. Now there were 3 different stages of the engine: stock intake and plenum, stock intake and plenum hotter cam, stage 3 was ported heads, intake, plenum and hotter cam, tune. No way to tell what we have here without looking.

Indmar only offered this engine for 2 years then switched to the LS based engine. I would say they made less than 50 over the 2 years, so very rare to find just the intake.

The only thing I disagree with is the marine industry just converts auto engines and does no R&D. While the majority do just use stock GM stuff, Mercury Racing engineers, designs and actually shares knowledge and R&D with GM on cranks, rods, cams, heads, intakes and supercharger technology, primarily on the big block side.

Check out Mercury Racing 1350 engine sometime, fully designed, engineered and manufactued from block to prop in house, all while carrying 1 year warranty and making well over 1000 hp. I was lucky enough last year to tour their facilities and see their process, very impressive.

874ME

iTrader: (1)

That intake looks to much like a Ram Jet to not be a Ram jet. It very well could be a marine version, but dont let that fill your head with dreams of secret HP potential.

All of the marine engine suppliers use mass proceduced production engines from GM. They used to use Olds and Fords also.
GM and Ford built crate engines for them that utilized HP parts from the 60's with specs for marine use. mainly this meant low compression, large rod bolts, 4 bolt blocks and in GM's case, recatngular port BB heads in higher HP engines.

In the mid 80's Mercruiser started experimenting on their own and came up with some trick inhouse intake stuff. I remember a guy bringing in a 86 Carrera daycruiser that had sunk. It had a strange fuel injected manifold ontop of a 350CID chevy small block. It was a rare peice and made more than 350HP. At the time the base BBC made 330 HP. In hind sight it looked like the T-Ram, large upper plenum and short runners. Still remember trying to buy it off the owner for my 71 camaro.

Mercrusier builds some bas *** stuff. If your Mercruiser boat engine is blue it is hand built and has alot of independent engineering behind. Mercruiser also assembled the original ZR-1 engine.

cal30_sniper

iTrader: (16)

Indmar may have only built a few of the engines with these intakes, but there were definitely other marine manufacturers out there putting them in high performance boats during those years. In fact, my sponsor dad's boat in Annapolis was a Vortec headed 350 with this intake hidden under a bunch of plastic junk. GM apparently started suppling this intake with its high performance marine engines when Vortec heads came out. You also see Vortec head marine intakes for carburetors, and factory TBI throttle bodies.

Perhaps I misspoke, the racing engine departments of the marine companies do quite a bit of R&D. Some of those engines are reliably putting down tremendous amounts of power, and running under extremely tough loads for extended periods of time. However, your run of the mill performance/recreational boats are almost all powered by off-the shelf automotive engines modified for marine use. The Vortec 5.7L marine engines are one of the major exceptions. Since the marine industry was not required to go to OBDII with the automotive industry, they stuck to basic TBI injection for the low-output boats, and TPI-style intakes for the high-performance boats (both the Ramjet 350 and the Ramjet BBC intakes originated this way). That's why you see a lot of the weird intake setups for Vortec heads.

Most of the engineering time spent on your standard boat is just trying to overcome the obstacles inherent with marine use. Marine engines have always had to do all kinds of oddball stuff with the cooling system and things like that. It's a lot easier to use cool lake water than carry around a radiator everywhere you go. That in itself introduces all kinds of issues with water that is too cold, corrosion, and overpressure. You should see the nightmares I had getting the Berkeley Pack-A-Jet cooling system working again on my Sidewinder. Definitely not your average automobile cooling system.

Don't forget Chrysler. 318s, 360s, 383s, and even some 413/426/440s came in a lot of boats back in the day. You still see a lot of the reverse rotation 383s floating around on craigslist. Bigger boats using two engines have to have one of them run backwards to keep from walking the stern over. Somewhere along the way somebody figured out it would be a whole lot cheaper to have an external gear turn the engine the other way rather than continuing to manufacture unique camshafts, distributors, and other odds and ends. You don't hardly see them anymore.

It is most definitely a marine intake. I already posted the GM instruction manual which clearly states that the Ramjet was developed from a marine intake. There's no HP difference between marine/automotive in this case, but there's a large difference between RamJet and TPI.

-cal30sniper

ChevelleFan

iTrader: (4)

I'm a bit envious, that's a great looking intake. I've been trying to pickup a Ramjet (or the marine version like yours) on ebay forever. They're hardly ever around -- either that, or my Saved Search is wrong. Interesting to see the slight difference in throttle linkage. If you end up not using it and want to sell it, shoot me a PM.

-Dave

APACHE JOHN

It's a ram-jet marketed by Arizona Speed and Marine and some one powdered coated it red.....want to sell it?

Johnny Blaze

iTrader: (15)

Did you read the thread?

DBLTKE

iTrader: (1)

I'll be installing the intake hopefully within the next couple months. I just finished building the engine for my GTI last week so the Camaro is next.

irocdls1

I like it I would use it quick..

anesthes

iTrader: (12)

It's a Marine intake made by GM, and sold to Mercury Marine.

Arizona speed and "MARINE" do sell them as well.

I'm guessing Mercury buys a heck of a lot more than AS&M.

-- Joe

Johnny Blaze

iTrader: (15)

Joe nailed it.

GM cast all of them.

Some go to GMPP

Some go to Arizona Speed and Marine

Some go to Mercury.

It seemed pertty weel established in the thread that this one was a Mercury version.


But rerally we are splitting hairs here.

cal30_sniper

iTrader: (16)

Any word on this project, DBLTKE?

Fallouthazard

Can you tell me exactly where on Ebay you found a Ramjet kit for that price? That's crazy cheap for that (compared to others).

Thomas Quinones

This will not fit into any ole SBC,, look for 10243880, and start from there.

anesthes

iTrader: (12)

Thanks for joining, and bumping an 8 year old thread. ..