its a fact, the 305 sucks. its also a fact that TBI sucks. i know this, you know this. so why does everyone have to constantly be so rehtorical and say this non-stop? so today in class i decided that with the budget of $1500 i'm gonna get my car to run 250rwhp or about 330hp at the crank. now this may not seem like much but this is the same as a stock LT1/LS1 so its big in my book. here's a rundown of what i got planned so far:

block: stock L03 non-bored
crank: 350 crank
heads: L98 iron heads ported and polished and flowbenched for flow #s
valvetrain: upgraded pushrods/springs and 1.6 roller rocker arms
intake: depends on results of flowbench but most likely a high rise
cam: depends on intake/results of heads
ignition: MSD/Malory
fuel delivery: bored out stock TBI and turn up fuel pressure from 42 to 50psi
exhaust: hooker 2055s with an X-pipe and straight out the back!


with this i will hopefully be at at least 250rwhp and the next step would be a tranny rebuild with a shift kit and 3.42s in the rear. mix that with some 275/60/55/R15s and i
d be one bad little L03 don't ya think? and for it to be at full potential i will definitely need some tuning.

and before you can say otherwise i'm doing this cuz i can

 

it's a good build-up, but it looks the same as all the other L03 builds to me. will be cool to see 250rwhp though. go for it.

 

A few things...

L98 heads are going to drop the compression, that is not what you need.

second, the 305 already has a 3.48" stoke, not sure why you listed a 350 crank in there.

 

yea but i'm hoping to get all that with a budget of $1500 and get 250rwhp. maybe down the road i'll go even more outrageous such as the new vortec heads, roller lifters, forged pistons, maybe a 4 barrel throttle body, more aggressive intake. maybe even some power adders such as as a roots blower and nitrous. i know there's prolly a post every other day about this but my goal is 250rwhp with only $1500 on a stock L03. hope i get there.

 

the 305 and the 350 share the same crank? i always thought they were different. i'm having a hard time finding info on the stock parts so its hard to compare. so i'd be looking for a 400 crank then? i'm not too worried about compression with the L98s since i plan on stroking it which will bump the compression anyways. as for bore its staying stock, i'm trying to go as low end as possible to take advantage of the torque. i could go with the L31 vortec heads and make windtunnels out of em but then i'd need a vortec specific intake manifold. this isn't all set in stone, i'm still trying to get all the wrinkles out. but i do appreciate the feedback, thats why i posted it here

 

the vortecs have a very significant midrang flow advantage. If *I* were doing this, I would go the vortec route, and get a singleplane for vortech heads.

 

WOW!! What injectors are you running 2.8s. Fuel pressure on a TBI engine is usually 11-13. I am running 14.5 with 454 injectors on my setup. 50 PSI is way up there, especially considering the stock pump will stop pushing fuel at about 16 psi.

I would mod up a set of 081 or 187 TBI heads then probably run the stock LT4 cam. That should make your 305 put out about 250 rwhp with the right other parts, headers, intake, no need to bore the TBI for this power level, 350 injectors, proper chip tuning, exhaust, etc.

I am making in the neighborhood of 270-280 RWHP and 335 ft/lbs out of a 350 TBI with the stock intake, ported 193 swirl ports, F-Body LT1 cam, custom chip, headers, and duals.

Here is the complete buildup.

https://www.thirdgen.org/techbb2/sho...hreadid=283217

 

It takes more than $1500 to get 250rwhp on an LO3 without nitrous. The 305 and 350 cranks are indetical except for balancing.

A few thoughts

-L98 heads will drop your compression a ton (go with 305 TPI or LG4 heads)
-You are going to need a big cam that will most likely need head work to accomodate (if past .470" lift) that (you are looking at $500 into the heads alone)
-You won't get any power without chip work so you will need to buy the stuff to do it yourself
-Don't rebuild or stroke the 305 when building a 350 is cheaper and will make more power
-You don't need new lifters of pushrods, only valve springs to match the cam

Here is a price break down for you to put these mods into perspective. This is comming from people who have already tried the $1500 build up. You need many more parts than the ones you have listed.

Cam - $50 (used) to $250 (new)
Valve springs - $50
Timing chain set- $50
Used 305 heads - Free to $100
Head work (you do not want to put a mystery mileage 305 head on your motor) - up to $500
Gaskets - head, intake, timing cover, header - $150
Hooker 2055's - $350
Cat-Back - $300
3" Cat - $100 (or a replacement pipe which will still cost money)
Fuel pump - $110
Intake - $100 to $300 (vortec intakes are $$$$)
Various fittings for said intake - $50
larger injectors - $50 to $150
Chip Burning stuff - $250 to $300 (you need this as your first mod)



You can see where this is going. Don't get your heart set on 250rwhp yet. I know, including myself, of plenty of 305 TBI cars with more than $1500 in mods that are lucky to be at 200 at the wheels. When you get close to 250rwhp you are bound to have problems. Little things always come up that make your car not run. My good buddy, and excellent chip burner, has a vortec 305 that should be near 240 at the wheels has his car stuck in his garage because of a fluke MAP and vacuum problem we can't track down.

You will also need a new rear gear with a posi along with lots of suspension stuff if you want to make that power stick.

I am not trying to burst your bubble and I still want you to mod your car. The LO3 does not suck but it is plagued with a lot of weak links that need to be addressed before power can be made. You cannot throw parts at these cars and expect to be fast. If you do you will be upset when your $3000 investment is now slower than when it was stock. It takes time to learn these cars and play with different tunes to get it where you want. As simple as TBI is it still takes money to go fast. The old hot rod slogan doesn't escape us 305 guys either. How fast do you wanna spend?

I make a good living with my career and my car is still slow.

 

i must have confused the readup i read for the TPI fuel pressure.

 

Another thing I will toss into the mix here....

low end grunt probably won't get you that 250hp mark. You need some RPM to pull that off, you will want to have everything ready to spin. And a cam/valvetrain that will match.

You may need pushrods, if you change heads, checking the rocker arm geomitry is a good idea, you may need custom pushrods. You not not need to change lifters though.

 

The easy way to get up to .510 lift on a stock set of heads is use LT4 springs and retainers. The retainer is shorter and will not bottem out as fast on the valve seal.

A good balance job on the bottem end would be nice too.

I found a brand new LPE 219 TPI roller cam on Ebay for $50.00 shipped to my door. I am thinking of sticking that into my 350. Only problem is the cam has .525" of lift on both sides. I am ready to try the single pattern cam theory on my heads.

Here is a 305 TBI with the following specs run through DD2000 for a rough guess. This is assuming proper tuning etc.

305 shortblock
Stock 187 heads (modified for extra lift only), 480 cfm stock TBI, performance intake, headers, 9.5:1 compression, LPE 219 cam.

RPM--------------HP----------------TQ
2000-----------140---------------368
2500-----------174---------------366
3000-----------212---------------371
3500-----------248---------------372
4000-----------276---------------363
4500-----------295---------------344
5000-----------297---------------312
5500-----------282---------------270
6000-----------255---------------223
6500-----------219---------------177

 

now that i look at it i might go with the with the L31 vortecs for around $600 and i can flowbench them and port/polish them myself (after practice on junkyard heads). for exhaust its gonna be hooker headers and no cats or mufflers (up to $950). intake is $300 or less for some of the vortec non-GM brands i've seen. i might even be able to apply my parts discount to those GM pieces so it'd be alot less than right now. cam should be about $300 depending on type. springs/roller rockers should put me at about $125-150. gaskets like you said are $150. why do i need a new timing chain set? and are the stock injectors and the fuel pump gonna really hinder me that much? right now i'm at 1850 but i might be able to get down to 1500 with my parts discount through my school. i know tuning is real important am i'm trying to get into that as soon as i can. would $2000 overall sound like a better budget?

p.s. i already have an auburn pro series diff installed. the new ring/pinion will come when i rebuild the tranny.

 

go with 305 TPi heads! and good luck i am getting some header, tpi heads, and lt1cam for my car this summer!

 

what is DD2000? and those numbers don't seem far off from my goal and thats barely anything done. as soon as i can get my alternative student load approved i'm gonna dive into the tuning world. (the load was originally $5000 for tools but i'm trying to bump it up to $7500 to pay for this litte escape). i'm really hoping to hit 250 rwhp n/a and reliably with your guy's help. since the write up in the tech section was for the fuel pressure regulator on the tpi can i get more information on the TBI? i'm planning on taking off the TBI unit in a couple of weeks and boring it out, if they're really neccessary should i do the bigger injectors then?

 

i'm trying to go with the vortec's now that i remember that wyotech has a parts discount with laramie GM. if i can go with as many GM parts as possible i may just fit in under my budget. what else could i get from GM other than the heads/intake?

 

http://www.chevyhiperformance.com/te...148_0208_vort/

according to this article i can get up to .525 valve lift out of these heads with modifications i can do in my schools shop with the help of some very good engine building instructors. i really want all the advice you guys have cuz i really want this to happen and 250hp isn't too much to ask is it? if i get good at tuning quick enough i can use our engine dyno and get it tuned before its dropped into the car which would be badass.

 

I am not going to say exactly how accurate DD2000 actually is because I couldn't tell you for certain. I know on my engine it is pretty accurate. DD2000 is a software program where you enter all your engine specs into it and it spits out power numbers.

I think your biggest hurdle to overcome is going to be the tuning side of it.

My TBI engine is running great for less than $1000.00. I hit a dyno'd 267 rwhp with a 350 TBI, milder LT1 cam, ported heads, bad CTS, and a poor tune.

People will be quick to mention that it cannot be done with a set of TBI swirl ports but it can. 1 cfm of flow makes about 2 hp on an average V8. Intake ports on a 305 TBI swirl port flow about 165 cfm stock. That is enough to make about 330 hp if the rest of the combination is optimized. It will take you about 305 HP to make 250 rwhp assuming 18% loss through the driveline.

Stock TBI heads flow about the same as stock TPI heads on the intake but better on the exhaust.

 

yea VorTEcs head are better!! sorry i suck at life!

 

Yeah vortecs are better but pricier too. Especially considering you have to get a new intake and the throttle cable bracket will no longer bolt up, amoung other things. They make a 305 version of the vortecs too that flow better than other 305 heads and let you keep the stock 305 compression ratio.

 

how did chevyhiperf boost the compression on thier 305tbi with just heads, cam, and roller rocker arms. i'm kinda trying to imitate them but just get a little bit more out of the setup. i'm trying to accomplish this by the tuning and flowbenching. roller lifters would be nice but but they're pricey too. i can easily take the engine out in my shop to work on it so is there anything cheap i can do to add to the vortec heads, intake, cam, and roller rockers?

 

Milling the heads and thinner head gaskets.

 

ahhh yes:

http://chevyhiperformance.com/techar..._0409_mission/



so would this definitely be in my interest too, this is all feasible since we have both a CNC and milling machine in our shops. they said that .062" was too much so i can do less and get it right the first time. and do you think i can get my stock TBI unit to flow 620cfm as well, or close by boring the hell out of it?

 

You need a new timing set becuase your old one stretches and is worn out. You don't want sloppy timing with your new cam. The stock TBI fuel pump is terrible and can barely support a stock car. You will never see the fuling you need at high RPM's with the stocker. Same goes for the injectors.

You nee dto fucus on the chip work though. Without it your car will be slow and be an un-drivable mess. Trust me.

 

Green92Rs305 check your PM

 

My Vortecs are milled .020 and I use the Fel Pro headgasket shim. Runs fine on 91/92 octane. It would probably run fine on 89 if I lost some timing.

 

speaking of the chp vortec 305 ,i think they would`ve gotten alot more out of that engine with some 2055`s and the hooker catback.sorry that`s been eatting at me

 

I had the same sorta buildup that you did done on my 305. I had the LT1 cam, 305 TPI heads which were sent to a machine shop and they were ported and polished. Then I had the intake replaced with an aftermarket intake by edlebrock. We then went to a junkyard and bought a 454 TBI and I had the same machine shop do some work on that for optimal flow. We got some better injectors not sure which ones but the mechanic I deal with got them. I then bought a rear end off of my buddy that came out of an IROC-Z which was a 3.73 Posi to replace my 2.73 PegLeg. Re-did the exhaust from a 2.5" magnaflow setup into a 3" setup going into a cat and then going straight out the back with no muffler.

Anywho, after all that was done I had the local performance shop do a tweak and tune and dyno and in the end the dyno showed results of 265hp @ 345lbs tq. Those numbers are decent seeing how the most expensive things I paid for was the machine shops time. I had $1500 for the buildup and when all was said and done and paid for I had $90 left so I bought some rum and coke and had a good old time after dusting an RX7.

 

so would it be in my interest to get a junkyard 454 TBI instead of my stock one. either way one or the others gonna get bored out with bigger injectors. and i see what your saying on the timing chain and fuel pump. i'm thinking of bumping up the budget to 2500-3000 so i can get everything done right while i have all the milling equip and the use of a shop for free. thankx alot guys for the help

 

I'm right at $2700 on my budget for total costs. That's parts and machine work, and I still don't have an intake manifold, and I'm not done lol.
pro topline vortecs with 3/8 screw in studs and guide plates, swirl polished valves, setup for .540" lift with 120lb springs
speed pro hypereutectic flat tops for 6" rods, -4 cc valve reliefs
10.1-3:1 CR
scat i-beam 4340 6" rods bushed for full floating
comp cam 1.52 roller tip rockers
true roller timing chain setup for LM roller cam
comp cam 264HR 212/218 @.050 .493/.501 corrected lift 110lsa
new speed pro roller lifters
fel-pro gasket set- had to buy vortec intake gaskets on the side
rotating assembly fully balanced - get your pretty bob weight card
melling m55hv pump and ss51 pickup
clevite main, rod, cam bearings
new head bolt set (2)
block bored .030 over and honed
surface decked
sonic checked, magnafluxed
the shop wanted my 193 swirl ports so I traded em those to knock off some of the machining
missing a ton of little stuff, and this is with my 20% off discount on parts since I order through the store's commercial account.
The heads, rods, pistons, roller gear and machine work make up most it up, since the dang machining ran me $600

 

sounds like a good build, but the thing is i won't have to pay for the machining if i do it myself.

 

Yeah, that was a pretty good article put out by Chevy High Performance. Did they ever get to run their creation at the track, or must we settle on how they supposedly smoked a 97 SS Camaro...

Not that they didn't, but if their going to make such a claim for everyone to read, they really need to back it up with some proof... especially for the TBI enthusiasts. They owe it to them.

 

The most recent issue dais that they will have track times in a month. I hope they do.

 

Not that this really contributes much to anything, but you mentioned that 250RWHP is about what LT1/LS1's are making....

If you are building a motor to compete with those motors, you are walking down the wrong path I think. I just say that in case you have it in the back of your mind that you are going to race a buddy of yours that has one, and win. Especially with the LS1 cars... they dyno in the 285-310 RWHP range bone stock. That would also partially explain some of the 12.89's and many 12.9x's bone stock timeslip's in some cases.

I take those numbers from what I've seen in person at Norwalk, Ohio.

Just a heads up, not bashing your project, just draggin you back to reality in case you were doing all this to beat one of those cars with even a modest driver.

(Before anyone gets worked up: I'm not saying it's because it's TBI, I'm saying this due to limited displacement and money invested in the project.)

 

i was going by factory rated outputs, i forgot that GM tends to underrate their cars quite ofter. but yea i'm not doing it to beat anyone or say i'm better than this i just want people to see my car and say hey that car is cool and then pop the hood and show em a 305 TBI. i'm doing it more to shut up the people that bash it rather to try and build the ultimate car.

 

smart man you are

 

Sounds decent. I was just reading into your initial post a bit too much I guess

 

d/p

 

I hope they do too. Last I read, they were installing a Holley Stealth Ram on their Third Generation Camaro project. I remember them cutting the fuel lines at the rear of the engine to cleverly hide the plumbing...

After reading that particular article, I thought that they had given up on their LO3 project (especially when the LO3 article ends with; "Mission accomplished").

Who knows though, I myself have been averaging about four hours of sleep for the last few months... for all I know, maybe that Stealth Ram project I had read about was written in Super Chevy.

Either way, I hope that some magazine decides to build, then test, a TBI project for crying out loud...