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Discussion Starter · #1 · (Edited)
In my situation... best V-8 & tranny combo? (price/ease)

First, I do not have the proper tools to rebuild a 350.

Right now, I have a worn-out carbed 305, & a SM465/205 combo in my junk. All accessories are good, new water pump, HEI is good, alt is good, PS is good.

I want to swap it out for an injected 350, with an auto tranny. Engine MUST make at least 250hp, preferrably around 300. I am looking into building a Megasquirt fuel injection setup, so I can handle a carb to FI swap, provided it's a TBI type setup. (Can make the whole FI system for under $500)

Obviously, a Vortec 6.0L/4L60E combo would be the easiest way to do this, but that combo would be BIG $$$.

So, the question: For the least amount of money (don't forget about computer re-programming issues if applicable), what would be the best way to get the power and tranny I desire?

Would a TBI350 with & 700R4, with some common bolt-on parts make that power? (roller rockers, maybe a mild cam, new intake?) Planning on a reverse full manual valvebody for the tranny. exhaust would be ram's horn manifolds to a free-flow (no cats) exhaust. no emmisions crap required.

Current plans are to run this combo with a NP241 with my current 4.1 geared Cruiser axles and 38's. Future plans would be to swap t-cases to a Ford 205 for Mog 404's & 42's. SINGLE t-case only... don't have the WB for doublers or the $$$ for an Atlas. I want the 700R4 for the lower gearing.. (every bit helps!)

LT1's are getting cheap, but then there's the opti-spark issue to deal with... relocations are a few hundred bucks..

This could become a good thread dealing with "bang for the buck", so let's hear it!
 

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Discussion Starter · #4 ·
well, 250hp is OK by me... as said.. as long as the torque is there and usable... but let's focus on the advantages/drawbacks of each powertrain combo?
 

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I would stay away from a tbi type injection system. A TPI 350 with cam from an lt1 would be pretty close to what you want, and could probably be done for under $1200.
 

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Well the words cheap were used so TBI can't be ruled out, nothing wrong with TBI anyways. TPI is known for torque not HP. but unless you have one of those 2 sec. mud boggers HP means nothing, even a tow rig needs Torque not HP. Most built motors will require a custom chip, done yourself less than $100 for all equipment/software, done by prof. $300+, hypertech and the like don't wast your money unless you want to spend $250 to make your fan come on sooner.

1. budget built TBI motor:
Nice running, 300 HP possible, not probable with cheap in mind. Computer easily modded and required.

2. TPI motor:
Great torque, 300 HP possible but unless serious porting don't expect much and won't rev anyways. Possible problem with intake plumbing. Computer easily modded and required unless you go MAF which makes intake plumbing hard sometimes.

3. LT1:
Water and opti don't mix. Computer still easily modded.

4. LS1:
Nice choice if you can get a junk yard one and still may be a little pricey. Truck motors are LS1 based so they are included. Computer mods can be very expensive even if you do it yourself.

My take on it anyways, didn't mention 4.3 V6 which i'm acutally using because you were talking about higher HP and would not be cheap for a 300HP 4.3.

Not including aftermarket EFI, why bother when GM junkyard parts are so easy/cheap to come by and unless big bucks are spent most aftermarket don't come close to the capabilities of the GM stuff, they spent millions for a reason, most probably don't understand how easy they are to work with, just takes time sometimes.
 

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Discussion Starter · #7 ·
ODgreen, thanks...

I think right now I'll be looking into a TPI engine for the time being.. the EFI I will be building does use all GM components, I'm just building the controller, and I can use a TPI-type engine, I'll just be running the injectors in batch fire mode... not a big deal.

My junk is primarily a rock crawler/trail rig... so yes, torque is far more important than HP, but I want to make it "fun" as well.. 250hp shouldn't be hard at all to get from a TPI 350, I think just freeing up the exhaust and tuning the ECU well should get me in that area, with a nice torque curve.

LT1's are certainly coming down in price, I've found a low-milage (60k) pull from a Roadmaster for around $1k... Yeah, optispark sucks though. I guess I'll find out what Frankie Fountain wants for his LT1 dizzy relocation.

Any other ideas, keep 'em coming!
 

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Well, a 350 tpi is at 245 HP already, corvette anyways. If your not going to swamp it then LT1 would be fine but the 350 TPI has more torque. For a few $$ you can go with a LS1 coil conversion on the LT1, just uses the opti for spark like a normal dist., eliminating all the know opti problems, pricey tho. The L98 in my vette has 330 ft/pounds of torque stock, probably has just shy of 400 with the superram on.
 

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Discussion Starter · #10 ·
Did a few hours of research on the L98 Vette/camaro engines... the Lt1 manifold really killed the low end torque, so I think a L98 will fit the bill nicely for what I want to do...

700R4 with a reverse manual valve body sound good behind it?
 

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I always herd from other people that there is a problem with the TBI setup and running a modded engine. Was told that the computer would not run that well with a cam (a small cam should work but was told that a more radical cam might act up). Not sure if this is true or not, could someone back me up or tell me if I'm wrong.
I've always wanted a LT1 and have been dealing with my carbed 305 till the money allowed me to buy one. I think that the LT1 is the best cuz you can swap it in bone stock and it's got all the power that I'd ever need and all the reliability cuz the motor would be stock.
With the 700r4 I've herd from other people (mostly drag racers and guys with street cars) that have said that you really need to do internal work to the 700r4 to make sure that it will take the abuse from the motor, something about taking out he 7 vain pump and replacing it with a stronger 10 vain pump. Also rebuild the tranny using the Corvette rebuild kit cuz everything in that kit is supposedly stronger. Again could someone correct me if I'm wrong here.
 

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Discussion Starter · #12 ·
There was a guy with a L98 Camaro who swapped on a LT1 manifold...though he gained 30hp and abou the same in torque, it KILLED him below 3500rpm, and the 1/4 mile times were nearly identical.

With 95% of my time going to be under 3500, I'll stick with the cheaper (and more torquey) L98.

Those drag race guys and hi-po street guys do indeed need the internal work... a 10 vane pump, .500 valve, and corvette servo are pretty good ideas, the latter 2 are normally part of a rebuild now.

The computer and cam issue isn't a big deal, I'm going to make my own computer, with my own code. Most I'd run is a 1200-5500rpm cam, nothing radical at all.
 

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Any Speed Density motor will require a chip mod not just a TBI one if you go even a little off of stock, MAF motors can compensate much better to mods not saying one is better than the other.

Which ecm are you going to use? Assume your going SD rather than MAF?
 

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Discussion Starter · #14 ·
Yeah, speed density, going to build a Mega squirt computer... cheap, effective, and completely tunable... It may take a few days, but i have no doubt I can tune that sucker even with a little bit of cam in it.

You're right thought.. when dealing with a OEM computer, MAF's are MUCH better at dealing with increased airflow...

But, when you can adjust your tables on the fly, and have control over every aspect of the fueling system, things become easier... just more involved.
 

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Well personally i'd stick with a GM ecm, very tunable and would have better control and actually cheaper. Since your gonna run a TPI you can get a 730 ecm for $25 at a bone yard that can do more, just have to reburn the chip which takes longer and replacement is again $25 but they last pretty well, no body can beat out old GM on that, especially since they've poured millions into research over the years and you can get em for nothing.
 
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