what do you guys think about putting 2 garrett t25 turbo's on my carb'ed l03. also if any of you guys could help me out with basic requirements that would be needed ( i already have a set of headers i can modify to work with these) as far as fuel requirements from what gm told me the turbos would make between 4-6 lbs of boost per turbo im getting the turbo's off of a couple of sunbird's dont laugh this is just a toy as im wanting to build a 355 that i can transfer the system over to. also the turbo's are free since my father in law has a salvage yard so i can get pretty much anything i want. and please no 305 vs 350 debates this is just for right now until i can get the money up to build a vortec headed 355. any comments or advice welcome , just none about i should just stick them on a 350. thanx in advance.


thomas

 

hmm nobody is responding to my question????? 47 views=no replies i suppose since its not a 350 nobody cares. oh well guess ill just have to figure it out on my own.

THOMAS

 

i figger them turbos are only good for about 150 to 175hp each :shrug:

 

above what the engine is producing now ? i think thats what you are saying if not can you be a little more specific?
thanx in advance.
thomas

 

well, I say go for it but if you do, ditch the heads, stock intake, and cam. I say this because I think you would make more power on that 305 with heads, cam and intake, then twin turbos on a stock lo3. those heads and cam won't let it really use the turbos.

 

What he said.

 

Another vote for what 1992 rs/ss said, plus adding you gotta upgrade the catback, air intake, and ignition to utilize the upgraded turbos.


If you don't have the $$$$ for these other upgrades just throw the turbos on those and the headers will shake the rust off.

 

lemme let you know something first of all I switched to carb, hei and I also have true 2.5 inch duals with 1 5/8 inch headers (hence no catback) , also which cam would you upgrade to so it will help the turbos and heads and intake(single plane or dual)? , Ill have the ignition taken care of have a pretty good idea on that.
on the heads preferably suggest some factory heads that I can port I can use since I can come across just about any heads since my father in law has a salvage yard that I live next door from.

 

Don’t worry about the heads so much… they’re not that bad, and work find for a small displacement/low rpm engine. If you want better, probably the best ‘80’s heads were the ones used on the earlier 305’s, like the LG4, L69 and L05 heads. Of course, you could always drop compression with a set of 64 or 76cc heads, and my first choice there would be some stock vortec heads.

The stock intake is a piece of junk… not really great for anything but a low rpm, low hp application. Carb… if you can tune it it does have a few advantages, primarily the fuel will cool the intake charge some making an intercooler not as necessary.

Go for it… it will be fun, if I had an LO3 I’d do it in a second, but I’d probably do it with a smallish (good for say 450hp or so) single turbo. I’d also keep the tbi… fun, good mileage and if built right even reasonably reliable.

 

i have a edelbrock streetmaster single plane its an old intake but works pretty well , also the lg4,l69 or lu5 heads would you have any casting numbers on them as most of the heads we have are already off the vehicles and on a shelf in our shop or in a storage van. plus one more thing is 9.3:1 compression too much to run between 8-12 lbs of boost (not sure how much that would put me at,a little help would be nice) and at what psi should my fuel pressure be. im sorry for all the questions but ive never done a turbo setup on anything and i really wanna do this.

 

........

 

There’s a few part numbers for them… probably the most common are the 416’s. Again, those are small chamber 305 heads, if you can get the compression to where it would be OK with them (they LG4’s had something in the mid 8’s, so it is possible), then they would be one of your better choices…

Vortec stuff should be easy to pick out since both the common castings will have a different intake manifold bolt pattern.



For a stockish setup, yea, it would be a bit much… with a good tune, good quench and a larger then stock cam it could work well.

Your base fuel pressure should probably be in the 5-7psi range, and you have to boost reference it so it always stays at that base + boost pressure, so you always have the same fuel flow.

 

but again, I don't have as big a problem with the stock L03 heads as most people do...

 

Ever see a flow test of them? Sure they have 185cc ports but that doesn't mean squat. There is nothing good about the design of those swirl ports. It's just a bad design and the only way around it is to boost the engine (which he wants to do).
Take a look at the sy/ty guys and you'll notice that the swirl port heads "work" with some high pressure but the guys running vortec heads are just as fast without the crazy boost. I prefer the higher horsepower with less boost approach while others like the high boost, difference of opinions. Only thing that can't be argued is that good heads will make more hp everywhere with everything else being equal.... but good heads aren't free as is everything in this hobby.

 

I third change out the heads, cam, and intake.

I would get vortec heads and matching manifold. Then just use the stock cam or a cam setup for a turbo. This will improve greatly. JMHO

 

this would be a good project for a stock LO3, if you start suping up the engine or increase the cubic inches I think these turbos are the wrong idea.

2 T25's good for a stock LO3, not good enough for a well modified LO3.

 

Are those the V6 ones or the V8… I haven’t actually measured a set but they sure act like they’re a lot smaller then that.



I completely disagree… as long as you work within their constraints (they’re great for lower rpm efficiency…) they work great. I’ve dealt with them on a few different setups, the most interesting were a 350 and a 383 both used in full size trucks… made for some serious torque monsters…



He’s asking about using stock heads with boost. He’s also talking about doing this on a relatively low rpm engine with relatively small turbos. This will never be a high rpm, low boost, high flow setup. If it’s going to make real power he will run high boost. I’ve already suggested that vortec heads would be better from both a flow and detonation control perspective, but if he’s going to stick to something “more standard” then the swirl ports will work as well/almost as well as most of what he’ll find in the JY.

Yea, wonderful, I doubt that anyone will disagree that some AFR 227’s, 18* or SB2 heads will make more power (and will all be vastly different from each other), but that’s not what he asked

 

Both the v6 and v8 swirl ports are 185cc. Yeah they act like smaller ports because they're trash, literally. This just goes to show you that port volume means squat, it's the shape that counts. Large engines should have large ports or small engines that want to make horsepower need larger ports, that's just a general rule. There's a guy running a 406 AFR 195cc heads in the 10's n/a with a miniram.... that's only 10cc bigger than the swirl port heads .
As for swirl port heads making monster low end torque... ummm let's put some things into perspective. They aren't torque monster heads, they're just crappy heads. They have "low end torque" because they can't make any torque at higher RPM because the flow is so bad. Hence the effect of low end torque. I have a feeling that people say "moster torque" to feel better about an engine that revs like a diesel. Put a set of the LB9 heads on the L03 and then boost it, that'll make MORE low end torque AND high end torque resulting in more "free" horsepower.
I just wouldn't waste my time turbo charging a swirl port engine. The results will be similar to the truck owners and that whipple charger..... disapointed. Straight shot heads will make more torque everywhere than a swirl port head, I'll dig up my proof if need be.
So my recommendation is go for the twin turbo setup and if anything the headers you make will work on any small block in the future. Just use the stock swirl port heads for making the headers/manifolds, get a set of junkyard LB9 heads from a TPI 305 for like $100, spend $50 cleaning them up, test the valve springs and slam them onto the stock L03 short block.

 

im pretty sure i can get a set of either 416's or a set of vortecs pretty easy so...... what about cam selection what kind of specs should i be looking for as far as it goes(and dont forget i do have a carb onthere) right now i have a edelbrock but will probably switch to holley.

 

For a 305, decent heads, twin turbo, budget..... stock Lt1 cam hands down.
I've got one if you want it for $25 shipped. And no I'm not just trying to unload the cam. It is good for power adders.

 

what year lt1 is it out of im doing some playing with DD2000 and read there are different lt1 cams out there so if i knew what year i could get a little more ball park guess on what id be making.

THOMAS

p.s. thanx for the offer i might be taking you up on that also.

 

The cam is from a 96 firebird, that's all I know about it. Just about any lt1 cam has the lift you need and the tight LS to keep boost in the cylinder. The duration is mild for a 350 but is a good 305 cam power adder or not.

 

1 more quick question does the cam you have a fuel pump lobe? i was reading some did some did not.

thomas

 

b4ctom1 im planning on getting the lt1 cam from jprevost and also getting the above said heads (ill either get the 416's and port them or get a pair of vortecs) what turbo's would you suggest im wanting to run twin's ,and also what vehicles would someone find them(since my father in law has a salvage yard) on since this will be a JY setup and dont want to put a lot of money into it,also im wanting good turbo's that would work over onto a 355 when i get the money to build 1.

 

I would have to suggest larger turbos then

 

Yeah.
Some good T3 turbo's like those found in the K cars. For a mild 355 (stock gm non-vortec heads) T3's should still be good. Going to a hybrid like a GN turbo when you're wanting to get into the 10's.... it's all about goals and not undersizing a junkyard turbo! Nothing like worn bearings and a shaft speed of 150,000+ to make for a immediate rebuild.

 

Crazy joe of toohighpsi went high 9s with a set of .60/.63 T3s on a more or less stock 351 engine so you really don't need much more than that lol

 

In a 3600lb thirdgen comparible to his ride? If so, then nice. I don't think I've ever seen a twin jy T3 setup in the 10's let alone 9's on an f-body. The mustangs on the other hand....

 

Good point.

I do believe his race weight was somewhere around 3400 lbs though.

the weight listed on the site is 3200, but i've been told it weighed more than that when the fast runs were made...those times aren't even on the site either.

 

That car is about 3200# with driver...

 

As far as the heads discussion, if I had nothing better to do I’d build a nice boosted engine for my truck with a set of swirl ports to show you what could be done… but if I was going to put the effort in (since I don’t have either sitting around and would cost about the same) I would probably just port another set of vortec heads and use those (I put together a 350 with some that I did last summer that put down over 400hp NA at the wheels in a friend’s dually pickup)

 

sorry i havent been on in a few days i havent been able to access thirdgen but now i can. have any of you heard of schwitzer brand turbo's? reason im asking is because i can get a couple of those for a real good deal just want some opinions.


thomas

 

yes they are fine but what size are they, that may not be fine.

 

Hey guys

Did you pick up that LT1 cam? If not, I'm interested in getting it.

 

ive decided to go ahead and build a 355 TT so if you want that cam and if he wants to sell it to you go ahead thats cool with me.

THOMAS