Hey guys, well my friend keeps bugging me as to how a 5 liter V8 engine only puts out 200 horses. Personally, I think that's a fairly low number for such a "large" engine as well (yeah I don't think 305s are tiny lol). How much can I get out of an LB9 for lets say... $1000 or less. I've seen a variety of different TPI intakes and runners but people only seem to talk about the 350/5.7 liter engines. What kind of bolt ons would get more out of my LB9? Mention anything, like intakes, blowers, cams, ECU flashers, etc. All while keeping fuel injection of course. Thanks!

 

Are you asking about the lb9 in the 91? If so, those engines came with the bigger cam from the l98. Those engines with the dual catalytic converter setup were rated at 230hp and 300ft-lbs torque from the factory.
With a bit of exhaust work (headers y pipe, full cat back) and computer tuning you could get them to put out 250hp without much trouble. I guess with a $1000 you can't do too much beyond that. But what's more important than hp is torque. That's what gives you that sit in the pants feel and that's where the TPI shines.
With head and cam swaps in addition to the above mods, you can exceed 300hp in the 305, but that's going to take a bit more than $1000.
The real question is what do you want the car to do?
Peak power doesn't always tell the story. Often times a broad power curve is more important than peak power.
You can do the same things to a 305 that people do to 350s. The reason why people elect to do it in the 350 is because of the extra potential in store of the extra 45 ci in the 350.
I hope this helps.

 

Yeah that's the one. But no mine doesn't have dual cats. I believe that was optional on T/As and standard on GTAs. 230 hp seems high for a stock 305 TPI. I know that 350s were rated at 235 so I highly doubt that a 305 put out 230. I've heard 205 hp for the LB9 305. Would it be possible to put in an even bigger cam? Give the car that yummy cammed grumbly idle. What about intakes/plenums/runners/throttle bodies? Everybody complains about the stock intake being too restrictive. I'm sure something could be freed up in there.

What do I wanna do with the car? For now, make it look nice and shiny (needs some cosmetics), but once I start working on the engine, I'd like the car to have more 0-60 power. Something that would eat up ricers and beat foxbodies at the stop light. I don't plan on street racing but the red lights are always fun. I'm also definitely planning on getting a higher rear axle ratio, can't stand that stock 2.73 I got in there now. What would I feel with a 3.73?

 

I would search around here for similar posts. It's one of the most debated subjects. You should be able to find some good power upgrade combos and price info. I'm more familiar with the 350 but I'll add my thoughts.

Only LB9's with manuals had 230hp. Autos had 205hp and 285 ft-lbs. https://www.thirdgen.org/1991-pontiac-firebird

305's can be built up but going beyond 300hp seems to require lots of $$. In the end you are going to spend more than $1,000 but you can plan it out so upgrades come in stages. I would invest in good catback exhaust with headers. This will really help power. I believe you can use some better cams like ZZ4 for performance that won't require prom tuning. Your car is a map system which I believe needs at least 17" of vacumn before prom goes nuts. Limits what you can do with cams before prom tuning.

Main problem with 305 are the poor flowing heads. You might be able to have them worked over some for more flow. There are limited choices you have for aftermarket heads since 305 bore is not standard 4" bore like 327, 350's etc. Here is an article about aftermarket 305 heads and changing cam.
http://www.chevyhiperformance.com/te...all/index.html

I think the only aftermarket 305 head choice are the World Products SB-Chevy S/R Torquer Heads at $1,000 a pair. http://www.jegs.com/p/World-Products...46698/10002/-1

You can also modify stock air lid for more flow. Cutting off lower air baffles will increase flow by 50cfm or 10%. You can make a "ram air" duct out of the fog light vents and make air lid taller. These last two are more involved and not sure if it would help 305 in your case.

TPI produces lots of torque so you don't need much gearing. I have stock 3.23 on my 350 and it launches great. I would go with that or 3.42 at the most.

Chevy designed TPI intake for 305 engine. Larger tube runners would help you out since you are increasing intake and exhaust breathing. TPIS sells larger tube runners. Accell also sells them with the tubes siamesed a little to move power rpm band up some. They are $400 new. You probably would be ok air flow wise by porting stock manifold base over spending $200-$400 on aftermarket.

Everything above can be carried over to a 350 engine build except heads. If you are thinking about 350 upgrade in future, might want to look into value of porting existing heads. Otherwise you could get S/R heads and have them with 305 for a few years. Then if you decide to go 350, your $1,000 for S/R heads would have been spread out over a few years.

You may want to look into supercharging with a procharger. Many people who have gone the 305 upgrade route say it's the best for power at reasonable price. Either way your car with 280-300 hp will surely eat some stangs and ricers.

 

Wow thanks for the info dude! Sorry if this is a dumb question, but what is a PROM? Is that the engine control unit or something? I heard that smoothing out the throttle body in a TPI engine helps as well.

How are these?
http://www.summitracing.com/parts/SLE-20002

http://www.ajusa.com/details/index/398/0/0/EDE%203890
(a bit pricey I know, but I'm sure some bargain hunting will help)

I also found this valvetrain kit on Jegs.com (typed in 305 engine)
http://www.jegs.com/i/Comp+Cams/249/08-600-8K/10002/-1

http://www.jegs.com/i/BBK+Performanc.../5014/10002/-1

http://www.jegs.com/i/BBK+Performanc.../1539/10002/-1

Just throwing all that stuff out there. I found a lot of random stuff on jegs with 305 entered in the search. All pricey stuff though.

Any more tips?

Oh and I searched the Prochargers with the cheapest kit that I found being $3,600.

 

Actually, the SD 350 in the 90-92 f-bodies were rated at 245hp not 235. 230hp is not a lot for a 305. In fact, many believe that these engines are under rated.
It has been very much debated, and I think many agree that both the 305 auto and 305 manual cars both got the l98 cam between 1990 and 1992. It is hard to imagine how a set of two catalytic converters and slightly larger exhaust manifolds will lead to a gain of 25 hp. Thus, as far as hp is concerned, the auto and manual cars for 90-91 probably are not that far off and what ever difference there is, could be equalized without too much effort.
A quick word of advice,
Start with engine, drive train, headers and exhaust first, then worry about making your car shiny and nice. It doesn't take much to scratch a nice paint job while working on mechanical stuff.
2.73 gears are definitely killing performance, but 3.73s are not going to be good either if you decide to stay with the TPI induction. They will cause you to spin out of the TPI's power band too quickly.
If you are set on spending the money to buy new heads, trick flow makes good aluminum heads for the 305, but they are not cheep. Many people actually select the vortec heads as an upgrade for the 305. Despite the larger combustion chambers of the vortec heads, which results in a drop of compression if you use the stock pistons, the gain in power more than compensates for that. Also many people have had good results with porting the stock 081 heads, which is a cheaper alternative. You don't want to go with a bigger than 1.94" intake valves with whichever head you decide to go due to valve shrouding, resulting from the 305's smaller bore.
If you invest in a set of good heads for the 305, the same heads can be used on a 350. In fact, a very cheep upgrade for the 305 is the aluminum heads from the l98 in the corvette. They have a 58cc combustion chamber which results in no loss in compression. The only issue to get around is the EGR system.
You should also search for Fast355's results with his 310 built. It will give you an idea of what a naturally aspirated 305 can do when properly built and tuned.
The most important thing to consider is that you need to become well informed before you start throwing parts at your motor in hopes of making it go faster. If you don't, you will end up disappointed. This site has a lot of good info and also a lot of knowledgeable people to help you make the right decisions in your quest for more power.
Finally, there is no magic bullet for this. You are not going to install a single part that's going to make your car a 12 second car (aside from forced induction). The key is to pick your modification parts in such a way that they work together. In other words, find 20 places where you can free up 1 hp each as opposed to finding one place that can free up 20hp.
Good luck

 

Those vortec heads sound interesting. Now are these the same heads that the Chevy pickups had with their 5.7 liter Vortec engines? If so, I can probably get those for cheap at a pull-it yard assuming the truck wasn't a C4C victim. Assuming what you said is true (which I don't doubt at all), the vortec heads sound like a no-brainer, considering that the increase in power will compensate for the loss of compression (lower chance of pinging/detonation too! Not that it's a problem already lol). The 'vette heads seem like a good idea too, but I doubt that I'd easily be able to find an l98 corvette parts car. And I'd have to look into that EGR system thing you mentioned since that's what I'm clueless about.

So how about 3.23 gears?

I'm not looking for a 12 second car, just something to give it some more ***** lol. And hey, if it wasn't for this message board, I wouldn't even have my 1991 T/A 'vert! (bought it off of a member here from NH). So I'll definitely be visiting often and be asking plenty of questions before I starting spending hard money/time on this. I have already learned LOTS thanks to TGO. With this board and my Haynes manual, I feel invincible.

 

Yes,
These are the vortecs, although some castings are better than others. You will need to purchase a different TPI base in order to fit the vortec heads. Not too big of a deal, but just so you know. Many people have done this mod.
Also, if you go that route, consider the comp cam xr264hr12. I went with the slightly smaller cam, the xr258hr12 in my lb9 with the stock 081 heads, and after the wide band computer tune it made for some very nice gains. No matter what you do, you are going to need a computer tune. These speed density cars are not as forgiving as the older MAF cars when it comes down to head, cam, intake swaps. Even with something as simple as headers you will probably need a tune to get the most out of them. But it all pays off at the end.
The aluminum corvette heads are not that hard to come by. Getting over the EGR problem is not that bad either. You just need to learn how to tune the computer, a fairly inexpensive task as far as the equipment is concerned and am sure that there is plenty of info and support as far as the know how is concerned on this board too.

 

saculia, that's some good info. Interesting to learn what you can do with a 305. I found this article on Popular Hot Rodding. They added 150 hp to a 305 engine however it is flat tappet, carb engine. http://www.popularhotrodding.com/eng...cks/index.html

musclecar70sfan, I wasn't trying to be condescending with my read some posts comment. I hate it when somebody will write a response and just say "search posts". At least offer some comments. Usually that will help you get an idea of what to search for. I was trying say that you should look into parts before you spend some money like saculia discussed. Itch to upgrade is always strong

 

Oh no don't worry about it! I didn't feel like you were at all. It's kinda hard to portray any sort of emotion on the internet lol. I'm really happy with the responses I got so far.

 

hmmm for under a thousand....


full exhaust i have long tubes and a magnaflow x pipe muffler in my car all in all it ran me about 300-350 dollars in parts and to have the muffler shop bend the tubing to fit...


then get a pcm for less tune cheap worth every penny and they did a great job for me...

all that will cost about 6-7 hundred...

then use that last 350 dollars and get a nitrous kit
spray a hundred with the timing 2 degrees retarded when spraying..you will eat up every fox body on the street

 

That sounds interesting, but I doubt that I'll ever be doing nitrous. My car is a convertible and there's hardly any room in the trunk for the bottles... or anywhere else for that matter.

 

if theres a will then there is a way....maybe a small nitrous tank lol or be creative ...

my bottle is in my 90 vette in the hatch along with my battery...there isnt much room left but it fits lol

 

My recommendation is stay NA. There seems to be a bit more satisfaction out of making an all motor car go fast. Nitrous is a quick fix that anyone can slap on.
If you decide to go the power adder way, pull the motor out and build it properly to handle reliably whatever it is that you throw at it. Also, don't forget an adequate fuel supply.

 

Exactly. There's just no satisfaction in pushing a button to make your car go fast. I forgot to mention that I'd prefer all-motor tips, without nitrous or forced induction. Thanks though!

 

if you dont wanna go power adder then you will have to spend a hell of a lot more than a thousand dollars...heads alone are over a grand not to mention cam exhaust and intake..plus a tune thatll get you a somewhere

 

Yeah but those Vortec heads that Sacula mentioned can't be too expensive, especially if I pick em up at a junkyard. Same with the corvette heads.

 

yeah if you pick up junkyard vortecs then you will probably have to replace some parts or at least it would be good to do and have the machine shop pnp them...and have em resurfaced or checked just to be safe..after that you are iinto the heads almost a grand....same with some vette heads i have a vette and the heads sucks unless you get them worked at the machine shop plus

 

It by no means costs a grand to have a machine shop rebuild a set of heads. I would say $200 -$400 tops for cleaning inspecting, valve job, and resurfacing. This is way cheaper than buying new heads.

 

so you pay roughly 200 for some heads at a junkyard and get them resurfaced/inspected valve job etc for another 400... so your in 600+ with these stock heads...sure they will flow better then your stock but you drop a bit more lets say 1200 on some nice aftermarket heads that chances are you wont have to or need to replace...

sure you can have vortecs for cheap but they dont flow as well as anything aftermarket youd have to spend another 500+ at the machinist to get them to flow as well as some nice afrs

 

Check out the link below. Brand new vortecs with valves for $550. Now if you are on a budget, that is a hell of a lot cheaper than AFRs or TFs and will do just fine for a TPI 305.
http://cgi.ebay.com/ebaymotors/NEW-C...item2556fcb9e8
By the way. I just looked at my receipts from the machine shop. It cost me $280 to have my heads completely rebuilt.

 

That's not bad, but it says that they fit 97 and up, but I doubt that they had 305s in mind lol. I guess a grand is a little low for engine work. So lemme change that, now lets just say "low budget" lol.

 

The vortec heads are a great choice if you can get them really cheap, around here there are always late model trucks in the yards and the heads go for about $45 a pop.

If you were to buy new the price jumps to around $600, a matching intake brings that to an even grand. At that point you have several better aftermarket heads to chose from that will fit conventional intakes.

Vortech heads can be made to work with conventional intakes and TPI intakes in particular are good candidates since the injector bungs add a significant amount of material to the top of the port helping the gasket to seal.

Some port matching is needed along woth the drilling and tapping of the bolt holes.

The trick is to get the best heads you can, spend some time examining each head before you buy. Remove a few valve springs and check the valves for play. look out for corrosion and obvious signes of dammage, and remember that SBC heads are identical from left to right so you can use any two heads on your motor regardless of what side they were originaly mounted on in the donor truck.

Some mods will need to be done if you plan on running significantly higher lift, but despite what you might read there are several options besides a host of expensive machine work. The stock valve guide boss can be gotten around with a set of conocal springs and/or a set of raised locks. Either option will get you in the range of a healthy street EFI cam on most Vortec heads. And since you will need springs anyway they are nearly a no cost solution.

The stock rocker studs are pressed in but instead of paying to have them remoced and replaced with screw in studs you can drill holes through the boss and stock stud and insert a roll pin. This will keep the studs in place with nearly any cam spring combo you will likely be running in a street TPI car.

If you have anything done getting the heads milled a bit will ensure a better head gasket seal and help bring the ports and runners into better alignement.

Higher ratio rockers are a cheaper and very effective option compared to investing in an aftermarket cam, a set of 1.6:1 rockers should help a bit without any tuning issues and if you search you can even find some 1.7:1 rockers for a good price.

TPI manifold parts are not cheap so I wouldnt go down that route except possibly for some runners, some easy and cheap porting of the stock plenum can make a real difference and some members have had success with siamesing the stock base, the theory goes that as the engine reaches it's typical peak well before 5K the ports start drawing air from the neighboring runner allowing the motor to extend it's peak power a few hundred RPM.

Something that has been over looked so far is the converter, even with TPI's low end grunt the stock stall of less than 2000 rpm is just too tight. A good option is the corvette/S10 converter from similar year vehicles. They stall about 400 rpm higher and make a significant difference. Typicaly I wouldnt recomend using a used converter unless it is from an exceptionaly clean or new trans, and given the amount of back breaking work involved in droping a 3rd gen trans without a lift and professional tools it's something you do not want to do over.


A big bore TB is a waste at this point, especialy for the money.

 

Aw jeez the vortec heads are a bit more work that I expected if that's true. And theres no way I could drop the transmission by myself. I'd have to bring it to a shop for that but that will probably cost big $$... something I don't have right now. OK so let me just clear this up. What's the FIRST modification that would be a good idea doing? I'm talking about a good starting point that'll give the car a slight boost.

 

Full exhaust (headers, y pipe, high flow cat into a good 3" cat back). If you want to make the most out of it, get the equipment and start learning how to tune. The exhaust might lean things out a bit, so the tuning will help you compensate for that and also will allow you to bump the timing up a bit. Also gears and a higher speed stall converter.
You are going to find out that the more you start doing things to your car, the more you are going to want to learn how to do things yourself. Otherwise, it will nickel and dime you to death, especially if you are on a budget.

 

^ true

Exhaust and intake are still the best first mods to make on nearly any car and $1000 should cover a complete exhaust if you stick to the moderately priced items.

Thats assuming your car is in fine shape otherwise. if you have any issues now is a good time to fix them while investing in better aftermarket parts, even if they dont do much right away.

Dropping a trans with hand tools and some jackstands isnt all that hard though it's not exactly fun. I did it with my TA last year infact but I made the mistake of instaling the old converter that turned out to be bad the thing is so tight that it'll spin the wheels at idle if the tires are on gravel!

Vortecs can either be cheap with lots of hands on work or bolt on and costing nearly what you would spend on cheaper aftermarket heads.