GM Performance RamJet 350

[VileZambonie]

I'm lazy now, and don't wanna do the leg work and mods to put an ls engine in it. 

But you're pretty much doing this anyway so if you've got the coin available to do it, why not look into the LS? It's really pretty easy to convert and you'd attain your goals.

[rich weyand]

I have a Comp Cams 12-238-2 in my engine. I LOVE that cam. It's from the extreme energy line. Stock converter friendly, good torque for towing and doesn't beat my gas tank up to bad. I just put a beefed up 4L60 behind it too. Capable of 500 hp or so. I'm currently putting out about 360 hp. Just for comparison, that's the same as a 2015 Chevy Silverado 2500 HD with a 6.0 Vortec.

Yeah, that's the higher lift version of the 12-235-2.  What heads are you running to get that horsepower?

[KWKENUF]

My .02 for what they are worth...

-The RamJet,  I believe,  is actually a good engine at a good price.  New block,  efficient head and compression,  and nice power band.  The only thing is,  don't plan on doing any mods.  From what I heard,  the controller was made specifically for that RamJet engine,  and is not able to be re-tuned for modifications.

-If you are looking at a short block to build off,  got with the L31...  http://www.summitracing.com/parts/nal-12530283/overview/.
4-bolt mains,  efficient head and compression combo,  and a roller cam.  It is very similar to the specs of the RamJet.  I personally would look at pairing this with a Holley Avenger EFI kit...  http://www.summitracing.com/parts/hly-550-816/overview/make/chevrolet.  Whatever kit you get,  I would make sure it can also control your timing system and that new 4L80-E transmission you are going to swap in too.

The above two will keep you in the SBC gen. 1 realm.  The option of going LS is intriguing also,  but make sure you compare prices of NEW engine assemblies when doing a true cost analysis.  Most claims of doing it for the same cost are speaking of used engines,  not new crate motors as you are talking.

[SomeTexan]

One of the reasons behind the ls swap is the option of cheap junkyard parts. Although a 5.3/trans/harnes and ecu isn't cheap, a clean longblock is only a couple hundred bucks. How many times can you replace the 5.3 before you hit the same cost as the ramjet? Or, you could have it freshened up before installing for a reasonable price. Or even built up over stock. You may like a new block, but myself and many others prefer seasoned blocks. A few heat cycles on a fresh casting and precision machining means nothing. Plus, 6 bolt mains, way better head design, and the tuneability of the vortec computers just blow away the sbc stuff. Of course, when the ramjet computer starts holding you back, you can modify an ls harness, and a good tuner can program it to run the ramjet. I have known people who have slapped a turbo on a stock 5.3, threw down 800+hp, and got 15k or more miles out of them, with a lot of passes at the strip. Guys who don't build the big boost all the time get 50k plus out of them. A friend has 227k on his 430rwhp silverado, no boost or spray, just a mean daily driver that gets 22mpg and tows his ski boat great. It's an ls1, alloy 5.7.

If you want no hassle until you mod it, then no hassle after the modd'ing is done, go ls. If you want to leave it stock, ramjet. If you have to stay sbc, but want to mod, aftermarket efi stuff is the way to go. Oh yea, trash the summit mag and hit the web. There are better quality parts for less money avalible out there. Cool stuff you will never see in summit and jegs. My life and my rides got better after I broke that addiction. Lmao

[LTZ C20]

Rich. I believe it's a long duration cam. I could be wrong here, isn't long duration a choppy idle and high lift a lopping idle? Because at idle mine sits there and cackles. Either way truck hauls ass. Don't hold me too it but I could have the two swip swapped.

As for my heads, I've got Dart Specialty High Performance aluminum heads. Here's the specs, copied and pasted from summit lol.

Summit Racing Part Number: DRT-127322

Cylinder Head Style: Assembled

Cylinder Head Material: Aluminum

Cylinder Head Finish: Natural

Combustion Chamber Volume (cc): 64

CNC-Machined Combustion Chamber: No

Intake Runner Volume (cc): 200cc

Exhaust Runner Volume (cc): 75cc

CNC-Machined Intake Runner: No

CNC-Machined Exhaust Runner: No

Combustion Chamber Style: Heart

Intake Port Location: Standard

Exhaust Port Shape: Square

Exhaust Port Location: Standard

Spark Plug Style: Straight

Intake Valves Included: Yes

Intake Valve Diameter (in): 2.020 in.

Exhaust Valves Included: Yes

Exhaust Valve Diameter (in): 1.600 in.

Valve Springs Included: Yes

Maximum Valve Lift (in): 0.620 in.

Outside Diameter of Outer Spring (in): 1.437 in.

Damper Spring Included: No

Number of Springs Per Valve: Dual

Retainers Included: Yes

Retainer Material: Steel

Locks Included: Yes

Lock Style: 10 degree

Valve Stem Seals Included: Yes

Valve Stem Seal Style: Umbrella

Rocker Arm Studs Included: Yes

Rocker Arm Nut Thread Size: 3/8-24 in.

Rocker Arms Included: No

Rocker Arm Nuts Included: No

Guideplates Included: Yes

Guideplate Pushrod Size: 5/16 in.

Valve Cover Mounting Style: Center and perimeter bolt

Accessory Bolt Holes Drilled: Yes

Intake Valve Angle: 23

Exhaust Valve Angle: 23

Valve Guides Included: Yes

Valve Guide Material: Manganese bronze

Valve Seats Machined: Yes

Valve Seat Machine Style: 5-angle intake/2-angle exhaust

Valve Seat Material: Powdered metal

Steam Holes Drilled: No

Oiling Style: Through pushrod

Machined for O-Ring: No

Heat Crossover: No

These heads are very good. High performance at a low price. I put steel roller tip rockers on too.

[78 Chevyrado]

Good replies guys.  Great info. keep em coming.

Main reason id like to keep a genI smallblock and th400  would be quickness of installation...  once i sell off my car n van, and the trucks apart, i have to borrow my moms car until its finished.  leaving her stranded...  so I can't have a lot of bugs to deal with...  I hate borrowing anybody else's car.   Also i'm not setup for nor am i any good at welding.

the 4l80 would add more bugs to iron out  but that one would be worth it in the long run.   

Actually i can wait a bit on the trans, my current th400 drives fine.  but i bet it won't live long behind a hotter engine for too long, since i have a lead foot...ha

I wouldnt mind having my current trans rebuilt but all the places around here want to do cookie-cutter stock and won't upgrade it any...  every trans needs to be upgraded...  even for a stock engine i want it to shift like a truck and i bet there's been updates since 1978...  ya know...

The ramjet is looking better and better.  may even not get the serp setup and keep what I've got...  it works well, and all accessories are a year old or so...  so i may not get it...

the ramjet not being easily upgradable is ok.  the ramjet IS the upgrade...  I can't see me messing with again after seting it up the first time.  I'm happy with the truck now, with the stock 350...  so this will be a big bump up in performance and i'll be ok with whatever i do now from now on. 

[78 Chevyrado]

Will a 4L80E physically fit in my truck?  c20, 3/4 ton, 2wd low hump.

Do i have to have a controller for it or can you get mechanical versions with mech lockup and all like a 700r4?  I've seen some 700r4's specd for 400hp and will move my 5200lb truck...  but ive broken too many 700r4's...  i just dislike em for something like this.  especially for heavy trailer towing. 

I have a 5200lb truck  Empty.  and a 8000lb  trailer i haul every year or two...  ya know just when a car breaks down is it that heavy...

I like the th400 because it's the ONLY auto trans in anything i haven't broken...  and I'm not too easy on em...  I don't drive like mad all the time, but when i want to, it better take it and smile.  so far my th400 has.

[78 Chevyrado]

Oh yea, trash the summit mag and hit the web. There are better quality parts for less money avalible out there. Cool stuff you will never see in summit and jegs. My life and my rides got better after I broke that addiction. Lmao

I learned that too...  I only use summit to give yall links, since they show most specs.  I price everything out seperately and all over the place before i actually pay $$$. 

Tho year one and summit tend to get a fair amount of my buisiness because summit is 65 miles away and year one is 4 miles away.   costs tax but no shipping.  otherwise i have no loyalty to a store...  i find the part number i want and i buy it where its cheapest.

[SomeTexan]

There must be someone at year one that could recommend a good shop to build your trans.

But, with dirty dingo mounts, I've had no problem dropping truck pull-outs straight into c10 2wd low hump trucks. Accessories and all, with the 4l80. Now, the mounts are adjustable, and were slid all the way forward to clear the a/c compressor, but it fit. Mounts fit easy, drops in just like any sbc. For trans cossmember, bolt to trans and clamp to frame, drill new holes and install bolts. You can order a custom harness, have the stock harness modified, or do it yourself. Lt1swaps.com has several set of instructions depending on year and model of engine. Lsx unlimited in my area makes and mods harnesses, and they ship. Only possible issue is the driveshaft. May need a different yoke, but will need to be shortened. Late model th400's are called 3l80's, can't remember if the yoke is the same.

[SomeTexan]

As far as I know, there is no mechanical 4l80, unless you could the 3l80, otherwise known as the th400.

[rich weyand]

Rich. I believe it's a long duration cam. I could be wrong here, isn't long duration a choppy idle and high lift a lopping idle? Because at idle mine sits there and cackles. Either way truck hauls . Don't hold me too it but I could have the two swip swapped.

As for my heads, I've got Dart Specialty High Performance aluminum heads. Here's the specs, copied and pasted from summit lol.

You're right, the lift is about the same as the 12-235-2, but the duration is a little longer.  You can get away with it because you are running about 9.5:1 compression ratio with those heads, so you have the static compression to use a later intake valve closure without the dynamic compression going completely south.  For the 8.5:1 compression heads, that may be a little too long for the bottom-end torque a truck needs, but with those heads, and the larger valves, yeah, it'll snort.  Camquest says 360 hp at 5000 and 425 lbft at 2500.  Nice.

[LTZ C20]

Thanks Rich. I thought so. You know your stuff to lol, I am right at 9.5:1. She is a definitely a hot girl. Did I mention she breaks transmissions??

Chevyrado, you are correct about not wanting to break your 400 with the new engine. I did that. I put that 425 ftlbs of torque into my old 350. She ran good for about 2 months. Then one morning, tried to leave home and no R & D from the trans. Now I've got that 4l60 in. That one is freshly built by a GM trans tech and upgraded by a lot. Haven't even driven her yet, still waiting on a driveshaft. But she's capable of about 500 horse. I've got room to flex if I suddenly wanna add a little juice to the engine down the road.

And here's a little piece of useful information. A 700R4 is a 4l60. After the bad rap that the 700 got a few years after being used, they changed some stuff, modified it and re-released it as a 4l60. What I have a 700R4 but there is a 4l60 casting on the side if the bell housing.

Sometimes is easier to say 4l60 because the look on people's faces is usually more of an "OH COOL" instead of an  "oh ewwww". Haha

[Captkaos]

N2TRUX has a Ramjet in his truck, he said it has nice power.





4L80E is essentially a TH400 with a overdrive, it will fit, I have one in my 1/2T Twin Turbo truck.

[rich weyand]

Thanks Rich. I thought so. You know your stuff to lol, I am right at 9.5:1. She is a definitely a hot girl. Did I mention she breaks transmissions??

Chevyrado, you are correct about not wanting to break your 400 with the new engine. I did that. I put that 425 ftlbs of torque into my old 350. She ran good for about 2 months. Then one morning, tried to leave home and no R & D from the trans. Now I've got that 4l60 in. That one is freshly built by a GM trans tech and upgraded by a lot. Haven't even driven her yet, still waiting on a driveshaft. But she's capable of about 500 horse. I've got room to flex if I suddenly wanna add a little juice to the engine down the road.

And here's a little piece of useful information. A 700R4 is a 4l60. After the bad rap that the 700 got a few years after being used, they changed some stuff, modified it and re-released it as a 4l60. What I have a 700R4 but there is a 4l60 casting on the side if the bell housing.

Sometimes is easier to say 4l60 because the look on people's faces is usually more of an "OH COOL" instead of an  "oh ewwww". Haha

Yeah, I'm running stock heads with the 12-300-4 cam, which is 422 lbft at 2500, but I don't have the top end you do, only 275 hp at 4000.  So up until 3500 rpm or so, I basically have the same pull, and I love it.  Have to keep those heads in mind, though.  That's a sweet setup for pretty cheap.

[KWKENUF]

Will a 4L80E physically fit in my truck?  c20, 3/4 ton, 2wd low hump.

Do i have to have a controller for it or can you get mechanical versions with mech lockup and all like a 700r4?  I've seen some 700r4's specd for 400hp and will move my 5200lb truck...  but ive broken too many 700r4's...  i just dislike em for something like this.  especially for heavy trailer towing. 

I have a 5200lb truck  Empty.  and a 8000lb  trailer i haul every year or two...  ya know just when a car breaks down is it that heavy...

I like the th400 because it's the ONLY auto trans in anything i haven't broken...  and I'm not too easy on em...  I don't drive like mad all the time, but when i want to, it better take it and smile.  so far my th400 has.

As Capt said,  yes it will fit.  Being 2wd the swap should be quite easy for ya.  Possible crossmember re-location and maybe driveshaft length alteration?  Others will be able to answer better than me.  IIRC,  90 and/or 91 trucks came with the 4l80 and basically a stand alone controller from the factory to control it.


edit:  Found this from another guy that did the 4L80E swap on his 85...

Hey brah...if you go 4l80e youll need the tci standalone controller ($600-about half the cost of the other ones on the market) youll need a throttle position sensor for your carb if thats what you have (runs about $130) and a little black box to convert the mechanical speedo to electronic signal...which is about 330 dollars. Then you just need trans. Move crossmember ajd may have to cut driveshaft depending on what you have