tilerob79

I have a 1990 Rs with 305 tbi with some mods, and want to swap to a 350. Ive been researching a couple, but want some different feedback.
what would be the best crate motor to buy for around 2500 to 3500 with intake, for TBI. i would like to keep that as the fuel system. im looking to get at least 300 HP.
Any body got any ideas, and would keeping Tbi be the best way to go?

CaddyMan

Why dont you just do a standard 350 build up. Get a decent block and go from there.

Also check Jasper, GMPP, etc for different options.

tilerob79

any body have any ideas, somebody knows something

thomas1976

I would opt for this one

http://www.sdparts.com/product/24502...ateEngine.aspx

Ultimate tbi mods, TPI fuel pump or bigger and 30psi AFPR should be good for 300hp. (a little bigger TB and injectors would help getting the full hp of that engine)

And EBL to tune it.

graebz28

iTrader: (5)

Look at the PDF at the bottom of this first post.

https://www.thirdgen.org/forums/tbi/...g-350-tbi.html

If I were to do it again, I would stick close to this build-up. You can opt for cheaper heads, etc. I think all crate motors are overpriced and you do not get exactly what you want.

tilerob79

the only problem with that, is that it woulld cost double to have somebody put the motor together, im not very good with a wrench, i mean with little things like changing an altenator, or water pump,but not putting a whole engine together.
but if you had to pick a 350 crate motor for around 3 grand with one would it be?

graebz28

iTrader: (5)

Sorry if I am still not answering your question, but how about a new assembled short block, then pick the heads,cam and intake you want. Summit and Jegs have both 2 and four bolt shorties. SDParts have the modified vortec heads, get an lt-4 cam or similar, and the GMPP or Edelbrock TBI manifold. I just finished building a used L31 and put in the cam, head etc. Not too difficult at all.

If not, just make sure you get a cam that will be reasonable to tune.

Kevin91Z

iTrader: (1)

The ZZ4 engine has older style bolt-pattern heads that wont bolt up to the TBI intake manifold unless you modify the center four holes.

Try this one:
http://paceperformance.com/index.asp...D&ProdID=42937

Combine that with an L98 or LT1 camshaft, use your stock TBI manifold or an Edelbrock TBI intake manifold, and it'll work.

95chevyTBI

o'reillys sells replacement engines for a decent price.

tilerob79

how do you guys feel about the GMPP 350 330/HO?

duderjay

dude

thats a non roller block and you wanna stick with a roller block

also budget for a tune or you will have gotten an engine for nonthing.

trust me on the tune i can relate to the pros on the site my work involves large staionary nat gas and diesel statiionary engines. Those in a manner of speaking you have to tune or they run at lower than spec hp and are fuel hogs while a smaller engine beside it running in good tune will make as much hp and less fuel consumption.

So budget if you don't have the bucks for a tune in my opinion your throwing your money away on a new engine

tilerob79

why how much would it cost to tune it.

and is a non roller block engine that bad, what are the pros and cons.

S105.7

Thats definatly ROLLER block. Its a 1 piece RMS, so at the most you would have to drill the "spider" bosses in the lifter valley, and get the retainers.

greg320

iTrader: (1)

Regarding the tune on the GMPP 330HO, cfm-tech has a kit with bored out tbi unit and custom chip for this motor for around $700.00. Its on this page http://www.cfm-tech.com/gm_tbi_camshaft_heads.htm. I do not know anyone who has dealt with this company. But I have read many posts here from guys who seem to think they are good.Can some of you guys comment on this?

duderjay

less frictional losses, more longevity. they can also take more abuse and such.

It depends what you want to do I guess. what what you want to do to the engine later on as well. That 350/330 ho is a good deal but from what I've been reading here guys say to do to a roller block. All stationary engines I work have roller cams.......

Also if you go to a non roller cam block I've read that you make have to do something with your knock sensor.

And for a tune don't get a pre tuned chip get some one who knows what he doing and tune your chip for your car and engine.

check out the tuning threads. I was a believer in buying a chip and being done with it but the guys who do the tuning know different. And now of the same opinion.

I'll take a new engine from the factory of after a overhaul and basically tune the electronic air fuel controller to the specific site, gas btu and altitude.

keep on reading the threads use the search function and see what people are doing and ask questions.

duderjay

i apoligise, What I meant to say was a flat tappet camshaft......hell maybe I am getting confused with engines I am in the process of shopping myself and looking at a bunch of engines.

tilerob79

ok so i go with the gm 350 330 HO, and change my intake to a GM vortec tbi intake

what do i do with my throttle body?
obviously replace it right, it cant handle 330 HP, Has anybody ever heard about that cfm. tech company. They sell a brand new throttle body for a 5.7 or a 7.4 (454) for 229.00 and then i would have to buy the GM injectors?

anyone got any other ideas?

graebz28

iTrader: (5)

I thought that the stock TBI maxed out 330. I would go stock and read what Dewy says about seeing if the map sensor indicated that you need a larger bore in the link below.

https://www.thirdgen.org/forums/tbi/...owing-tbi.html

Dyno Don

iTrader: (7)

With all the additives being removed from oils today, the last thing you would want is a flat tappet cam.

Camshafts are going flat at an alarming rate.

titchener

The stock unmodified 350/305 TBI's flow around 490 cfm and are good up to around 300 HP or so. If you are going to go with the 330 HP crate motor, a stock TBI unit bored out to 46mm will be a good fit, they flow around 590cfm and should be good to 340HP.

www.cfm-tech.com, www.turbocity.com and www.xtremefi.com are suppliers of bored out TBI units. Don't go with a 50mm unit on that engine, more flow than an engine needs will give you less HP.

As far as the injectors go you have two choices, get big block injectors which will allow to run close to the "normal" TBI pressure range or use the more common (and cheaper) 61# 350 injectors and run higher fuel pressure, you would need somewhere around 28 psi so for 330HP with the 350 injectors. The Walbro 190 fuel pump would do the job well for the higher pressure approach.

Paul T.

tilerob79

After doing more research and money situations, i was thinking about going with the crate brand new L31 and the GM vortec tbi intake manifold.
what would i have to do with my throttle body then, i have a brand new stock fuel pump put in a couple months ago, if i replace the throttle body and go with the holley 502-6, will i still have to change my fuel pump.

How would all that work out with the stock L31 as compared to the 350 HO?

keeping in mind i already have hooker headers, magnaflow catback, and 3.73 gears with posi.

vorticaldavid

iTrader: (1)

dont forget at very least a torque converter from a V6 s-10(not sure on the years but i think 1 from a 97' should work, and a shift kit/corvette servo will really wake up that old 700R4 if you havent done that already

titchener

I believe the L31's are good for around 255 HP in stock form, so if you go this route your current TBI will work fine, the 350 and 305 TBI bodies are the same, so you currently have around 490 cfm of flow which is plently for 255 HP and it gives you some room for enhancements, as I said earlier you would be good up to 300 HP or so.

There wouldn't be any real advantage in getting the Holley unit with this engine unless you like their tuning setup. You would get some benefit out of upgrading the cam a little in the L31 though, this would probably be the best bang for your buck at this point, and if you have the dough to spend to make the tuning easier I'd go with an EBL ECM unit from www.dynamicefi.com.

With the 255HP engine you can use standard 350 injectors (61#) and keep your current fuel pump, but you can't use your current 305 injectors with the stock pump. Used 350 injectors are pretty cheap and easy to acquire though, and www.witchhunter.com will clean and flow test them for around $18. each.

I'd mount a small pressure guage on the TBI though to make sure you're getting good fuel pressure, and during the tuning process you may find you need to bump it up a little so you may need a regulator kit or external regulator, but you could hold off on that to start.

Tuning this combo correctly will take some effort and its best to learn how to do this yourself, trying to use mailorder chips on mix and match combos like this is pretty hit or miss, some people have ok results, some don't, it seems to be about 50-50.

Paul T.

DarkShark

To that point, I have had three non-roller blocks with TPI. Two crates and an L82. You can run a non-roller engine with EFI- it is just important to get someone who knows what they are going to tune the engine. Then again, that is always a good rule of thumb.

I've had chips from PCM for Less, Scott Hansen, and Street & Performance. Scott's tune is by far the best- he's also about the easiest guy to work with. He's very much into the details of the engine and he knows his stuff backwards and forwards.

tilerob79

thitchner thanks for all the info, ill let ya know how it all works out.

Do you think that the L31 has just as much potential as the GM 330 HO, and im better going that route. I mean either way its definitely a huge upgrade over my 305. and that L31 with the right headers and exhaust setup, and rearend should haul butt.

titchener

It depends what your goals are and how much you have to spend. The L31 isn't going to be near as fast as the 330 HO but its going to be more streetable and get better gas mileage, so if $ is tight and this is a daily driver I'd go with the L31, as you said its a big pop up over your 305. This is not a bad engine to start with as a building block, the vortec heads are capable of 400 HP, so as time and money allows you could build it up to that level later if you decide to.

But if you have the money to blow and you don't mind giving a lot of it to the gas stations, go with the 330 HO, but its a pretty lumpy engine for a daily driver. I hate to say it, but the way gas prices and the economy is going the L31 probably makes more sense, but you only live once, so go crazy on it if you can afford it.

Personally I was planning a pretty aggressive 383 build up for myself, but now I'm rethinking that. My engine has to pass smog inspection so that makes it a little tougher. I'm thinking a vortec headed 383 with a fairly mild and streetable cam, something like the HT383 (its not too different from the L31 cam) but set up with forged pistons, forged crank and a big bottle set up on it, so for daily driving its pretty mild but when the urge hits, crank the bottle open and let 'er rip. This approach would work on your L31 also as long as you didn't go too crazy on the NOS as it doesn't have forged pistons.

Paul T.

Fast355

iTrader: (2)

Paul, don't be so quick to pass off the L31 as a push-over compared to the 330 HO. The stock L31 is rated at 245-255 NET HP depending on application. The H0 350 is rated with a large 750 cfm carb, high rise dual plane manifold, and large equal length headers with a very low restriction exhaust, using an advance curve suitable for a dyno. Tested the same way the L31 would make ATLEAST 310 FWHP! In the same car, tuned, they would be around the same power and the L31 will be more street-able.

vorticaldavid

iTrader: (1)

how would you go about doing that? just swaping cams and springs? then a carb/vortec manifold with an adaptor for tbi-carb and tuning? i've thought of doing this myself but wondered how to get above the 300 hp mark with this set up

tilerob79

well it seems to me if i go with the L31 i can save on a fuel pump, and new throttle body and probabably a couple of other things, and still get it pretty close to 300 HP and down the road i could maybe put a different cam in it and other things. As to where the 330 HO, i have to swap the fuel pump, redo the whole tranny, and get a new throttle body. If business picks up for me in the next month ill probably go with the 330 HO because the car is a weekend driver anyway. but if not ill go with the L31, Fast 355 loves that motor doesnt he. from what he says its the way to go.

One more time if i do go with the L31 and keep my throttle body, what injectors do i go for, the cop car ones? does anybody have a part number?

duderjay

I am in the same boat looking for an engine to stick in my car. That L31 is looking pretty good. I went and checked it ou after reading the thread.

Also been reading quite a bit of info on the vortech heads and the power potential.....L31 in the future could a montster....

titchener

Yeah, that's pretty much it. There are some GM cams that you can get pretty cheaply off Ebay as new "pull outs" that will bump up the power on this engine nicely without getting too crazy for street usage. A nice thing about the L31 is the Vortech heads are pretty flexible, they perform well with the stock cam but also make good power with a bumped up cam. The only issue you need to worry about with stock Vortec heads is they don't take much cam lift, around .470" max but you can go higher by using beehive type valve springs.

As far as daily driver GM cams, in rough order of decreasing drivability vs. increasing HP tradeoff you have: L98, HT383/RamJet, LT1, LT4/Vette.

Probably either the LT1 or LT4 cam would put an L31 over 300 gross HP, and all these cams would work with the stock vortec head valve lift. It would probably be best to upgrade the springs thou.

I'm sure if Fast355 is still tuned in he probably has some good cam recommendations also. These roller cams from 3rd party companies can get pricey, so its often best to use a GM cam if its a good fit for your usage.

Paul T.

duderjay

Ive read some guys machine the tops of the guides or grind down the valve retainers the part which faces the valve...all this to get more clearance for more lift.

Next I gotta read about these 1.6 ratio rockers what they do exactly for a car engine...