hi i am looking to try to get 300 hp out of my lo3 305 tbi engine i dont want to use nos, turbo, or supercharger. what would you suggest doing other than a engine swap? The reason i want to do this is my friend has a stock 89 mustange gt and i want to blow it away and he set the standards of keeping the tbi and the same 305 with out nos, turbo, or a supercharger. Is it possible and how much money will i have to soak into it?

It is a 89 camaro RS with a tbi 305 lo3 5-speed.

I have a k&n filter flowmaster exhaust and 3.42 gears


Thanx

 

Not possible, sorry.

 

first... let me say: A LOT OF MONEY

now when we got past that part... i'm realy not sure...

I'd start looking at the car as a whole.. not just the engine. Get it light, stiff and agile and you'll be much happier than with 300hp in a car that handels like a freight train..

the posi you got is a good base. keep it and try not to abuse it for laughs

the engine is gonna need new heads, intake, headers and lots of work in the valve train.

a tbi off of a 454 would give you enough flow and the ecu is gonna need alot of custom chip tuning.

you're gonna need a pretty radical cam to get above 300hp..

but why 300hp? why not set you're goals on out running the gt? and what do you mean by blowing it away?? light to light? the 1/4 mile?? 1 mile track? oval? auto cross?

remember one thing... the car you're building is for you and your goals. not anybody else. There will allways be a faster one

 

well you see his car runs a 14.9 on the 1/4 adn i can stand his mustang he thinks it is the best thing out there. he said that he would pay for half of the mods that it takes under his rules. (He is rich). He doesnt think that i can get it there but if i do he will pay the half. I figure that it will take around 300 hp to get into the mid 14's in my car does that sound right? he has about 250hp i think not sure just has a intake and small bolt on's.

Mine ran a 15.5 with the stock rear end. I havent installed the other one yet.

 

Anything IS possible

Just depends how much $$CHA CHING$$ you wanna put down to do it.

I hope to do a rebuild on my L03 to get somewhere around that ammount of power out of my '92 RS. A good resource you might wanna check out: L03 Website

There is a lot of content, but don't skip a word. It is very useful and almost inspiring

-Joe Bliz

 

300 hp 305, I can see it. But it'd be hard, theres a few tbi guys (me included) that are pushing some good power, and times. But thats with 350's or 383's. And whats happenig is these motors are making a lot of tourque, but starving a on the topend for horse power. So its possible a to have a good qauter time. A 305 has no touque (well Ok its got some) so its hard to make a tbi 305 fast, with the lack of high rpm HP.

Just my thoughts

 

Well your buddy is partly right. His fox body stang is cheaper and easier to get quicker then your car. And dicking with the 305 is a waste IMO. Build a nice car, *** what your buddy is doing. With that said I say build the car for a high performance engine, then drop in a good engine (read not LO3).

 

When he isn't looking install a 350 .
300hp will get you into the 13's with the 5 speed. If all you're looking to do is get into the mid to low 14's then here's the combo you should use.
- Ultimate TBI mods and double up the injector pod gasket
- Open element air cleaner
- Lt1 camshaft
- Edelbrock headers or the cheapest 1 5/8" headers will work
- 3" exhaust, again, cheapest you can get and yes, the Summit 3" welded muffler is a good muffler and sounds great
- bump the base timing up and play with the fuel pressure so you don't starve the engine with quick TPS movement (open element will do that)
- Performer RPM intake with carb to tbi adaptor plate
- 350 injectors are a must, start with 12psi and go from there recording the differences with "feel" and actual performance measurements (track or dyno)
- 4th gen rear end with at least 3.42 gears and a torsen posi, or get the torsen posi from SLP for $99 and install it with gears into your 3rd gen rear
- Good rear tires and no front sway bar, be under 3300lbs with driver and you're doing good

That'll get you into the low 14's EASY, especially with the 5 speed. If you want 13's, you'll need to swap out those stock heads for something like the vortec (need a new intake) or vette aluminum heads (zz4 crate motor). I personally like the vortec heads because of there smaller port volume and better hp (BSFC). They are one of the best heads for any 383 or smaller small block chevy making less than 450hp. It's a no brainer unless you're pinching penny's and already have an older style intake manifold.
Then with the heads run a nicer bump stick, the summit cams are great for the price! If you really want to keep the roller than expect to pay about a hundred more bills at least. The idea behind the lt1 cam is the cost. The cam can be had for cheap and uses your stock roller lifters and hardware. This cam will NOT support 300+hp n/a out of a 305 TBI!
Now does everyone see why I went with a 350, lol.

 

Oh no not Black Echo's site showing up again...

 

Heh that was the first site i found about building up the lo3, then i found you guys and you always bash it. He does get carried away in the end, but he makes some good points to start out with. Basically just breather mods and gears/suspension. But good info for a noob.

 

yes, filled my head with lots of crap and pipe dreams until i got here and got several rude awakenings. literaly

 

Okay Okay Okay... so inspiring isn't exactly the best choice of words... but you have to atleast admit that it is still informative.

Yes it gave me a lot of hopes and dreams... and they were all shot down... but it was still somewhat entertaining to read.

 

yes i suppose you could call it informative. of coarse you could call it misinformative too. im half kidding. you just have to decipher his opinions from the facts. he blends them together quite well. all in all it was cool, now i know you can do things with these cars(i honestly thought there was nothing you could do to them), and it brought me here.

 

are 302 blocks still available? i assume it had 4 bolt mains with a huge cam. i think the old Z28's were 7000 rpms? with a single plane would the holley TBI systems support enough fuel/air flow? keep in mind that car was not very good on street and would need a high stall convertor.

 

I would think a big inch small block would support more HP then a 302.

 

To get an original 302 block is hard, but you can get any 350 and buy a crank from Lunati or some other aftermarket manufacturer. The cost/benefit ratio is pretty low though......

 

Enough fuel? Yes. Enough airflow? Not likely, though never tested as far as I know. Stock ECM? I don't think so, IIRC the fuel and timing charts only go to 6,350 rpm or so.

 

Don't listen to these nay-sayers. It's VERY EASY and HIGHLY possiable to get a TBI3 305 well past 300hp.

If you're truely intrested, IM me on AIM at BadBlue91RS.

 

in 1989, hot rod magazine got close to 300 flywheel hp out of a stock shortblock 305 in their project f-notes.

the work was done by the now-defunct traco engineering. the former owner of traco engineering is now head of engine development for calloway corvettes. i've spent a bit of time talking to him.

they used a stock tbi unit. no ultimate tbi mods, but they did install 350 injectors.

the cam was a reground stock unit with .480 lift.

the heads were a set of aluminum 350 vette heads (the ones with the "d" shaped exhaust ports. anyone know the casting number of those?). they were shaved .035 inch.

the intake was a 2101 performer carb intake with an adapter they made.

peak hp was 271, with torque peaking at 306 lbs ft.

with the benefit of 14 years of cam and head development since then, getting 300 hp should be possible. those aluminum vette heads weren't even ported. a set of world products torquers or vortecs should easily make up the difference.

i've gotten hammered in the past for bringing this project up, but i still think it's viable. this guy makes a living developing engines for reeves callaway, i think he'd know what he's talking about.

 

its viable but why be happy with just low 14s

 

the car ran low 14s in that article, but the suspension was never worked out. no sfcs, boxed lcas, relocation brakets, etc. they had major wheelspin problems.

also, the engine made too much low end torque, adding to the traction problems. while i'm a huge believer in torquey street engines, too much of it under 2,000-2,500 rpm leads to nothing but wheelspin. i think with 1 3/4" primary headers and a performer rpm or single plane intake to move the torque curve up a couple of hundred rpms and some suspension work, that combination would easily be capable of 13.50s.

i'm in the process of slowly duplicating that combination, dyno and track testing after every change, so i'll know at some point. i've run a best of 15.94 so far with an essentially stock engine and going to a 3.42 posi. i'm currently in the process of installing slp 1/34" dual cat headers to a 3"in, dual 2 1'2" out dynomax muffler. i'm adding a vafpr at the same time, as i believe the freeer-flowing exhaust will cause it to go lean.

i'll dyno tune it in that condition and get track times, then add a performer carb intake. probably have to get into chip burning at that point. i'm hoping to see mid 14s at that point.

the next step will be cam and heads. looking at one of the bored out 2" tbis and 350 injectors at that point, too. depends on whether the wideband 02 sensor on the dyno says i need more air and fuel. my goal is 13.50s to 13.70s at that point.

we'll see what it does.

 

going out of your way to "make" a 302 isn't a good idea. the only reason chevy did it was to comply with the 5 litre limit for can-am racing.

it's fun as hell to drive a car that revs to 7500 rpm, but that's not the smart way to go for a daily-driven street. you'll make a lot more power much easier with more cubic inches and torque making max power below 6,000.

you also won't spend as much time picking pistons up off the street.

 

a well balanced big cube engine is pleny capable of 7k, you just need to build the valvetrain to handle it, and have heads, cam , and intake capable of making power up there on a large cube small block.

we just finished a 383, miniram, AFR combo on my friends firebird, that 383 is so well balanced it will spin to 7k with no issues at all, of course he has a rev kit, and the miniram and afr's and a 238* roller cam allow it to make power up there.

 

if he wants to maintain a mini small block and hit the big numbers a 302 with huge cam and TBI would be a neat ride. issue may be drivability but still a through back to yesteryear Z..

 

aside from everything else, i don't think there's any way to flow enough air through a tbi to support those rpms

 

Exactly why I said.....cost/benefit ratio......