GM Performance RamJet 350

[LTZ C20]

Yea. It's a GM Performance block too, 4-bolt mains, 30 over bore, double roller timing chain. I love this engine.

Her peak is right around 5200 rpm but she will spin 6000.

[LTZ C20]

Block is a fast burn 385. Doesn't have any original parts tho. New bearings, rings, rods, pistons, only thing to match original to the block is the crank.

Built her in my garage and installed on plywood covering in my dirt backyard. That's the first engine I've ever built.

[78 Chevyrado]

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.

I forgot about that truck...  I read his build.  thats a sexy truck inside n out.

[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.

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

basically i" wondering will there be any cab trans hump problems.

I don't know if I can get a 4l80.  the one i want is $2700  plus controller.  but i can get a th400 rated for 900hp for $1400.    I finally found a local trans builder id trust and they will build it like i want.  Don't know yet if i can afford it or not.

Either way ill get the engine n exhaust setup, then see what i can to trans wise  then if anythings left ill get a powertrax for the rear end.

[78 Chevyrado]

I'm liking that ramjet 350 more and more...

power chart for it...




TQ is what I need.  it also has a better than stock idle.  and i have a 5300lb truck to move.   


Here's the trans I'm looking at.  guy is local and I hear nothing around but good.  and I know I have nowhere near 900hp...  but I don't think a trans can be overbuilt.  I'm impressed with the TH400 stocker in my truck now...  it's the only auto trans i haven't broken yet...  thats quite a feat.

http://www.maddogtransmissions.com/TH400_Transmission_p/l3%20th400.htm

[78 Chevyrado]

I AM SET ON ONE THING THO.  Whatever it is, it must be fuel injected, and have a roller cam.   I want it to be set up so i can only gas in it and drive it.  no tinkering later on, like i do now with my carb.  must have AC and PS.  otherwise, I'm open to ANY suggestions.   

Understood.  Given your parameters, I think the Ramjet 350 is a good choice.  Anything else with 400 or more lbft of torque will be more money. I looked at it myself, but I'm a tinkerer, so I kind of like the retro hot-rod setup.

I do enjoy tinkering, and trying to make it a little better to try and get that 0.00038hp increase...  always have always will...  but NOT ON MY DD.  on my toy, yes.  but my DD needs to run and not need anything but gas n oil changes.   I haven't minded the tinkering i have to do to the truck now because i have a van n car to drive...  but to make all this happen, van and car are going away. 

I also like this idea because, far as im concerned...  I love the body and interior on my truck.  every other possible part could be upgraded as much as possible and id be happy.  I want the look of an old truck with the newest non-cosmetic stuff available.

Id drop my body onto a newer 2500hd frame but the frames hang down so low under the cab i think it's ugly.

[78 Chevyrado]

One other thing. 

I don't wanna scrimp here...

But ill need a fuel pump that supplies 35GPH and 45-55psi.

It will be an inline pump.  i dont wanna replace both tanks and rewire everything for dual tank service.

What pump do you recommend?  I'm great at plumbing so if i have to put it in a wierd spot not to get vapor lock i will, or build heat shields for it.  it will have dual exhaust.  Plumbing is a small problem.  I'd rather do plumbing than wiring for the dual tank setup...

Now I ask you this...  how does this sound...  my plan is...

Okay I have dual tanks a splitter valve between them that goes into a single steel line up to the engine.  new engine requires a return line.

I want to mount my inline pump in the existing steel line, close to tanks as possible.   i want my RETURN line to connect to the existing fuel line, BEFORE the fuel pump.  My logic is that fuel gets sent back, fine, but whichever tank im using, connecting to the line right before the pump, will be low psi, before the pump, and everything returned will go back into the tank it came from making the fuel available again for the pump to use of of the current tank.

I know i can get two in tank units for a tbi n upgrade them to tpi specs.  id also have to rewire everything to use an 87 tbi dual tank switch.  this is not desireable.

I know they use in tank pumps mainly because they are in the fuel of the tank and stay cooler.  no vapor lock.  I can mount my pump somewhere unconventional, or make air scoops to cool it or whatever.  I don't wanna drop both tanks or take my bed off.

So inline it is.  not the perfect solution, but my decision.  so if ya can help me think up how to best implement this. 

Thanks fellas.  yall are wonderful, love this site the most.  has the best ppl on the web
Kenny~

[KWKENUF]

If you are going to go through all this for EFI,  DO NOT SKIMP ON THE FUEL SYSTEM!!!  Do in tank pumps,  there is a reason all the new cars have them.  Your fuel system is the most vital part of EFI.  A guy I work with did an LS swap into a 76 Camaro and had problems with it for the first year.  You know why...  external fuel pump.  He went to an in-tank Phantom set-up and all,  literally all,  his little problems went away.  Just saying.

[SomeTexan]

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

basically i" wondering will there be any cab trans hump problems.

I don't know if I can get a 4l80.  the one i want is $2700  plus controller.  but i can get a th400 rated for 900hp for $1400.    I finally found a local trans builder id trust and they will build it like i want.  Don't know yet if i can afford it or not.

Either way ill get the engine n exhaust setup, then see what i can to trans wise  then if anythings left ill get a powertrax for the rear end.

Where are you looking for 4l80's? Junkyard core for a couple hundred bucks, then a stock rebuild. I've got several friends who drag race with these transmissions, they buy junk yard pull outs and run them until they let go. And you would be suprised how long a stock, 100k mile, 80 will last behind a built 408 with a 96mm turbo. Remember, it is a th400 with overdrive and other improvements, not a modernized 700r4. I run 80's behind 6-700rwhp builds, and they last.

Buy a lq9/4l80 combo, slap a cam in it, and you will wonder why you ever even thought about another small block.

Like KWKENUF said, in-tank pumps are the best. And, electric pumps need to be near the tank, so if you are running dual tanks, you need 2 pumps, don't expect one to draw through the selector valve. Internal pumps are cooled by the fuel and last longer, and are quieter. You would need 87 tanks and valve with return line set up. Or you can run 87-91 blazer/suburban tank under the bed. The stock in-tank pumps would have to be upgraded, I believe 96-98 pumps fit and provide enough pressure. Also, if you want to run an inline pump, you will need to sump your tanks. You would still have to remove them, but you would also have to cut and weld them too.

You really don't want to send fuel back to the feed line. Return fuel usually ends up with air in it, if you suck it right back into the pump, you will have issues. If you want to keep your dual tanks, you need an 87 tank selector with the switched return line set up and 87 tanks or sumped older tanks and 2 pumps. No getting around it.

[78 Chevyrado]

This sounding worse and worse.  Not your guys fault.  I want to do it CORRECTLY.    But $$$ means compromises.

Been talking to my dad.   He says and I feel he's correct for a DD He wouldn't have the truck with a 3 speed in it.   Dunno if i can afford the 4l80 and such.  and putting the fuel pump in my dual tanks is another huge hurdle.  dual pumps, more wiring to dual tank switch.   

plus the ramjet is the quickest n easiest but needs premium fuel...  i wouldnt have minded that when there was a 20 cent difference cheap to premium but thats gone forever...

The truck isn't worth all that.  I've already dropped at least $15k into it.  everything been done is top of the line, but dang..  I love the truck, never want to let it go, wanna keep it forever.  but its not worth all that $$$$$$$ and effort.  especially when while it's apart i have to borrow my moms car till its done.  Im almost 34.  I don't wanna borrow mommas car no more...  I will for a week or two but thats about it...  She'll let me and have no problem with it but i know shell be stuck...  i can't do that to her...  though she'd smile the whole time...  maybe thats reason more i don't want to have to drive her car ONE day.  I may not do this afterall.  may keep it like it is and keep it carbed and when the engine blows get the replacement 290hp 350 and keep it carbed. 

Been looking at selling off my van car n tractor and get an 01-02 camaro z28 or ss. 

Those are the LAST cars I've been excited about...  I used to test drive them lots when i was 21 and they were new...  they still sexy cars. 
What ya think?   Then i get a camaro and my truck...   how would my fleet pic look with my truck and an 01-02 z28 or ss next to it?  That's the only car i can think of would make me happy and excited to own.

It's just sounding more n more like this isnt a viable option for a DD.  I know im asking a lot of it.   so maybe ill keep it stock and sell the car van n tractor n get me a camaro to hotrod.   

[rich weyand]

I think you're being more realistic.  There're a lot of other changes that go along with moving to a modern technology engine.  Not that you can't do it, but it's big bucks unless you rebuild salvage yard pulls, and that's probably not a daily driver from a reliability point of view.

But don't get the 350/290.  The torque curve sucks in the bottom.  Definitely not for a truck.  I paid $500 bucks more for that engine over the 350/260, and had it re-cammed in the truck a year later, which was pricey at shop rates.  That cam is for a much higher static compression Corvette engine, and it is too long a duration for the 8.5:1 heads on the engine.  End result: poor low-end torque.  And it's an old-tech grind.

Get the 350/260 and toy with it when you need to replace the current engine.  No big deal to re-cam the 350/260 before it goes in.  And if you add the Dart Specialty heads that LTZ C20 is running, the thing will be a land missile.

Actually, you could put the Dart Specialty heads on the 350/290 engine, and that would probably work out pretty well, but $500 extra for that cam is a lot when there are even better cams you can go to for $100 if you are pulling the heads and voiding the warranty anyway.

[csdineley]

What I would get is the GM Crate L-31R (Vortec 350), and a Vortec carb intake. Like $2200 if you shop around. This is what I did when my engine blow up. It's no hotrod but it does have more power then stock. Keep the th400 for now. Later on you can switch to the 4l80e when you can.

 Mine is also a 3/4 ton truck, but with the Vortec 350 and quadrajet, sm465, and a 14bsf axle with 4.10 gears I avg 14-15 mpg driving 55mph. Starts up on the first try every time and so far has been very reliable. Next I'm saving up to switch the axle to a 14bff with 3.42 gears. To try and get the mileage up a little more.

[LTZ C20]

I again second Rich's motion lol. "Land missile" haha new truck name. That be a great license plate.

[rich weyand]

LND MSL  --  That works. 

And, Kev, with 425 lbft of torque, 360 hp, and revving to 6000 rpm, that's exactly what it is.

Criminy. 

Maybe next build/rebuild. 

[LTZ C20]

Rich, I haven't actually gone full bore on it yet. Shortly after it was fully broken in is when the trans went out. I hopped on it once or twice but never just balls to the walls. Gonna try that after get a few miles on the new trans.