CrazyHawaiian

I used to own an 89 RS with the L03 and at that time the general consensus was that it was a waste of time to mod, not worth the time. Now I see that people are getting more creative and a DIY'er can make some alright power numbers for fairly cheap. My uncle recently bought a 92 RS from a board member for dirt cheap ($100) and with about $200 into it we've got it running. The car has a high mile L03 that blows alot of smoke (rings or valve seals), so we already planned to take the engine out. I still have the L03 from my 89 RS on the side here (chassis is gone), bottom end and 187 heads. I also happen to have a Edelbrock Airgap intake manifold for 87+ SBC (not the RPM, the regular Airgap). So with all these recent posts we're considering going for it with the L03 and seeing what happens. We're thinking maybe disassemble the L03 from the old 89 RS and home port the 187 heads. Then put it back together with an aftermarket cam and the Airgap manifold with the TBI adapter and swap it into his 92RS. Then I guess we're gonna have to re-tune the chip. Do you guys think this is worth the trouble? He dosnt really have a specific power number he wants to make, just wants the car to be fun. I thought this might be a cheap way to make a fun torque motor. What do you guys think?

ShiftyCapone

iTrader: (7)

A lot will depend on your ability to tune the chip. It will be required to match the results that have been posted on TGO. Dewey ran 14.5 with the stock untouched heads. A full exhaust, mild, cam and some tuning really wake these cars up. I would stray from the air gap intake though. You could possibly have fuel atomization problems and fuel could puddle at the base of the intake. You really want a hot intake for TBI applications. Another carb intake of your choice with an adapter plate would be the way to go. Either that or port the stock one (if you still have it). You can get a used LT1 cam for under $50 and new valve springs and seals will set you back another $60 to $70. Carb intakes are cheap and you could even port the head while you have them off. If you want a fuel efficient daily driver that has decent power, there is no need to replace the 305 you have.

CrazyHawaiian

Thanks for the reply! We dont really want to replace the 305 since we're on a strict budget for this car, but we know something needs to be done because it blows alot of smoke and has alot of blowby. So I guess we're gonna use these left over and extra parts and see what we can do. I will have to look into the possible atomization problems you mentioned, would that be an effect of running EFI on this type of intake style? Another question, is the LT1 cam really a good choice for this type of build? I thought these modified L03 builds were more geared toward torque and lower RPM power 5,500RPM max. Thanks again for the reply.

azvolfan

If you have to put any money into the head, don't!!

Look for a set of 081 heads. They are the '87 & up TPI heads and they can usually be had for cheap if you can find them.

If the heads don't require any work and you on a budget then keep them. But if you have to spend money, spend it on other heads. Check out my sig for some modding ideas for a 305.

GOY

For my personal tastes, the LT1 cam is way too small, even for under 5500 performance if you can beleive that. For instance, in this build they used a larger cam, but made peak HP at or around 5100. With a larger cam than that, who knows where peak could be? http://chevyhiperformance.com/techar..._0409_mission/

I am not sold on ported swirl ports in the least. Look to vortec's or WP heads as a budget replacement. Even if you could get the SP's to flow as well as vortec's, you are still stuck with an old combustion chamber and less than ideal plug placement.

If I was to be in your shoes (which means everything to follow is my opinion), and wanted a bottom $$$ 305 with decent power, I would get a set of factory vortec's, plane them .030, and a mild roller grind - one that wouldn't require new valvesprings (remember - low buck). Then get an Edelbrock Performer vortec manifold, adapter plate, injector pod spacer+adjustable FP regulator, and obviously rebuild the short block. Then get to work with a prom burner.

CrazyHawaiian

Thank guys, really appreciate the comments! I totally agree that these heads are not worthwhile as far as spending $$. We'll have to see what everything looks like when we have them apart, hopefully it'll be cheap/easy fixes. The good news for us is this extra L03 I have on the side here from my old car has a good bottom end, around 60k miles on a rebuild. The heads from that motor might be in better shape than the ones in my uncles 92 RS. I'm not even sure what max lift is on these SP heads, I'll have to look into it. If it turns out they're all jacked and require $$ I'm gonna strongly consider your recommendation GOY. Those vortechs are a good bang for the buck, would just have to sell this airgap intake to buy a vortech style one. Hopefully we can get away with a fun build for dirt cheap with what we've got! I already got stuff to tune too (from my other cars). If anyone else has comments please add your .02

kdrolt

CrazyHawaiian's entire approach is low-budget, so I agree on using a larger cam as a concept, but I would also use whatever inexpensive used roller cam that can be found. i.e. F/Y LT1 cam, or F/Y L98 cam (same as 89-93 Caprice copcar "773" cam), and failing those I'd even opt for the 94-96 Bcar L99/LT1 and 96-99 C/K/G L31 cam.... because they're all warmer than the LO3 peanut cam.



The chamber on the 193 iron head (350 swirl) is identical to the one on the 187 (305 swirl) and on the 083 iron head (350 TPI), and both have projected plug placement in the chamber (hence ideally located). All are newer designs than the 416 head, which is reputed to be the same as the 081.

I don't know if the chamber on the LO3 (187 casting) is worse than on the 081, because the 081 is reputed to be a 416 casting that uses centerbolts on the VCs, and the 416 is an older head/chamber.

As for the chamber shape itself, it's is not that far removed from the one used on LT1 and L31. The heart-shape isn't present on the TBI heads because they lack the secondary squish but otherwise the chambers are similar. I had both in my garage (iron LT1 and iron TBI) for a while so I got to see just how similar they were.

Vortec's will require a Vortec intake. Used Vortec heads+ Vortec-compatible intake is going to be $400+ minimum. WP don't require a special intake but used is still $300+ (if you can find them... which might be harder if CrazyHawaiian is really in Hawaii). The 081 are an option but again, it's an added cost and the claim that they are superior (stock or ported) is suspect. I doubt any of these fit into the budget framework. DIY porting does, so long as the guides on the 187 heads aren't toast.

As for lift, IIRC the stock GM production heads (swirl port, TPI, LT1, Vortec) all have potential for clearance at the valve guides when the lift gets near 0.470". So the F/Y LT1 cam won't have a problem.



In contrast and IMO, I'd go lower $$$. I'd buy brand new valve springs & seals for the Bcar LT1 or L31 truck because they're cheap. I'd combine the retainers and locks from the two LO3 engines to allow elimination of the exh rotators retainers, freeing up weight. I'd keep the LO3 heads and port them. No planing the heads. I'd find an F/Y LT1 cam so I could keep the stock 1.5 rockers.

The largest expense should be the block refreshening, followed by exhaust work. You don't want to skimp on the exhaust. You might be able to sell the airgap intake to create cash for the cheapo build, and in that case I'd port the stock LO3 TBI intake incl the divider between the bores and then weld closed the exposed water jacket holes near the bores. Using the stock intake also avoids the need (expense) of the adapter plate. And Fast355 got good results even when he used the factory intake, so IMO it's a good choice for a cheapo build. HTH.

kevm14

What about those of us who don't have spare SBC parts? Maybe I should order a set of iron LT1 springs, keepers and retainers. What do I do with the rotator? I also assume that it would be a good idea to change the valveseals at that point.

How about rocker arms? Cheapo stamped 1.6s? Or roller rips? Full roller? What about the knock sensor? I think what I'm going to do is try to do new valvesprings and longer rocker arms (roller or not) and see if I can get a few extra HP out of my L05. And a timing chain might be nice.

GOY

Kdrolt, you have seem to have historicaly picked me as the guy to single out and disagree with. That's fine. Small cams that you may not be able to find used and ****-poor as cast heads build power. POWER of course seemed to be the point of the post, with money being a secondary consideration. If money was primary and power secondary - I'm sure he would have just ported all of the factory equipment, because after all, that is the cheapest possible route.



Anyways, back to being productive, CrazyHawaiian - just be sure if the vortec's are used to plane them down to reduce the combustion chamber size. If you do end up using one of the ported swirl port castings, single pattern cams can work just fine on them for the most part. You will find that there are guys who will live and die by swirl ports and others who see no logic in it. With a lot of work the SP castings can flow just about the same as a stock set of vortec's, but the port's are MUCH larger by that point - a consideration such as port velocity never to be accounted for apparently - and the chambers are of an old design. Or just buy a set of vortec's, plane them down, and have more or equal flow, smaller faster ports, and current chamber design elements. Its already understood you need a new intake so there's no additional cost there.

Since I haven't seen it mentioned - check out the Ultimate TBI thread as well. It should be a sticky.

kdrolt

Do you think I'm picking on you? Don't flatter yourself. You have an opinion, I have a different one. We each have our reasons and we don't have to agree with each other.



Really? $300 for the whole car makes budget primary, especially if L31s + intake cost more than the car itself. It's either a very low-cost driver, or it's a low-cost car that could then be sold (to another prospective 3rdgenner) for a lot more (with performance mods) than they originally paid for it:

GOY continues:

and ironically enough, a negative claim (poor port velocity) that has had no effect on performance (from the ported SP exercises that have actual measurement data), instead of the hand-waving GOY is offering.

BTW the poor port velocity would show up more at part-throttle and low-speeds, so it would have sluggish performance under those conditions and emissions would suffer (from the poor burn). GOY -- please post the links or the data that prove the effects you've claimed. That way CrazyHawaiian will know that there is no logic in using them.



Yup. Almost as old as 081/416 heads, and as old as the 3rdgen's they've been installed into.

BronYrAur

iTrader: (1)

Does every single post about "what can I do to improve performance in my car" have to turn into this bs debate? There are many many posts on swirl ports and what they can allegedly do with port work. Hell its a sticky at the top of the forum; what do you say we just help the guy out with a performance build and knock the "my way is better than yours" mentality.

It's all a matter of money, how much you have and how much your willing to spend. If you dont have any money at all and want some more potential out of your engine, port the stock heads. If you have money to spend, buy Vortecs. Simple as that in my eyes at least. Vortecs have the most potential to make power of any of the STOCK SBC heads. Port those Vortecs and you've got a great head.

But honestly, this topic has been beaten to death and then beaten more just to make sure its dead.

to Crazyhawaiian, if the car is stock, before you even touch the heads or anything engine-wise, you should get a good set of headers and full exhaust all the way back. Then get gears and a posi unit out back, then worry about heads and cam.

GOY

CrazyHawaiian

Thanks again guys for the ideas! I do agree this topic of heads has been discussed alot, but I dont mind if people discuss it some more in here because each persons situation is different. For us we are ultimately driven by budget on this car, so porting the stockers is the way we want to go if everything works out for us. So far kdrolt's plans are what I think match up the best with what we're trying to do, but GOY does have good recommendations if the stock heads turn out to be damaged enough to warrant spending money. We definately dont want to be dropping money into these stock heads. You guys are right, its not easy to find used SBC heads here in Hawaii, I think E-Bay would be the way to go in this case.

I had figgured if there was one part of this build here that we might want to consider spending a little money its the cam. Do you guys think this is a dumb idea? I guess it would depend on how different the results would be between a cheaper OEM cam and an aftermarket one versus the price difference.

Does everyone agree that I should sell that Air-Gap intake for this type of build?

In the art of re-using what we already have for a low cost build this car is getting the ultimate treatment. We do have an extra L98 cam here so that would be the cheap way to go if we decide to stick with OEM cams. We have a set of Hedman shortys here left over from the old 89 RS, he just has to buy the y-pipe, so thats some $$ there. Some guy I work with did exhaust on his '02 Z28 and gave me all the stock exhaust for free, so we're gonna be using the Hedmans and OEM exhaust from a '02 Z28 for this build. I know not exactly the best setup but its the cheapest way for us to go and the exhaust on there right now is rusted out. We have a few extra rearends laying around, my uncle decided he wanted to go with a 9bolt. So we will be swapping in a 9bolt w/ 3.27 gears and posi (this is an old rearend from my old drift car, posi still working good). Only catch is we need to rebuild the calipers and the rotors didnt have enough meat to get turned. So that'll be some $$ there but he'll have 4 wheel discs when thats done. Car happened to come with aftermarket drop springs and Tokiko struts/shocks. I think this is going to be a fun build for under $1000 for everything!!

ShiftyCapone

iTrader: (7)

Dewey316 almost made 300 hp with stock untouched 187 (305 TBI) heads. He also ran a 14.5 with a cam, 3.42 gears, full exhaust and a lot of tuning. Tuning will be the key to any cam swap. With ported stock heads and an L98 cam you should be able to get away with the stock injectors and have a solid 230hp or so (if not more). We all agree that swirl port heads are not performance pieces but if you can duplicate what Dewey did I think you and your wallet will be pretty damn happy. If Dewey were to port those heads I have no doubt that he would have eclipsed the 300hp mark.

Here is how I look at it.

You will install a full exhaust and rear gears with any motor you choose. I would take those out of the question since you already have solutions for those areas. That leaves you with the stock LO3. Porting is free (heads, intake and TBI)(assuming you have the tools/bits) and you already have an L98 cam. You will need new valve springs to match the cam and you should really replace the timing chain. There is a solid $100 to $120 for both. You can get away with the stock TBI and injectors (if you stay with the L98 cam) which will cost you nothing. You may need a different fuel pump if the stocker is still present but you can have a Walbro delivered to your door/tiki hut for around $100. You will need new top end gaskets (intake, timing cover, head ect) that will run you another $100. Tuning equipment can be purchased for $200. You are looking at $400 to $600 for a basic and simple build with parts that are already in your hand or easy to obtain. You will probably see a solid 50hp gain over stock for an $8 to $12 hp per dollar ratio without any hidden parts or expenses. That is a pretty good, cheap, reliable, easy to tune and fast build if you ask me.

I realize that there are a lot of well intentioned opinions floating around but you just have to sit down and look at the domino effect. You can always go crazy and get a huge cam with "other heads" but that will require larger injectors, fuel pump, better tuning skills, larger TBI unit, better intake ect ect. Leaving out one of those will more than likely cause you headaches as you try to determine why your car just doesn't run right. Take it from us who have been down this road and who are just now, albeit years later, just getting around to correcting it. I would rather have fun with 210 to 230hp with 300+lb ft or more a car that drives like it should, with parts that I know will bolt right up without any additional work or tuning headaches.

My buddy runs shaved non-ported vortec heads and an LT1 cam on his LO3 and by no means was it a cheap transition. The car runs great but not fast enough for what he paid.

CrazyHawaiian

Yeah I hear you man, that domino effect you speak of is true, and it could cause this to stray from being a budget project. It was Dewey's results that got me interested in this idea and I would be really happy if we could replicate his results. I'm curious how much power he would have made with an OEM cam like L98 or LT1. Do you guys know of anyone that did a similar build to Dewey with OEM cams? A 50hp gain would make our day!! I am still a noob to tuning so I'll have to spend alot of time on that. Lucky for us we already got the tools, just need to buy the definition file for the L03 ECM (forget the number and mask). Thanks again everyone!

kdrolt

Accounting for it, Dyno Don writes:

... I put a pair of those heads (193's) on a '96 Vortec 350 short block. It made 210hp & 330tq. to the rwhls. I then did some porting experimenting on them. You're right on the 168 cc's I had them flowed beforehand and was shocked at the results....178 intake 146 exhaust (on a standard Super Flow) I was able to increase the cc's to 175 and the flow to 196 intake and 183 exhaust (didn't measure ex. cc's).

per this thread:

https://www.thirdgen.org/techbb2/sho...hreadid=177465

So the port volume for Dyno Don was 168 cc unported, and 175 cc ported. 7 cc of metal removal. To put that in perspective, that's roughly the summed volume in the valve reliefs on a sbc piston crown.

AJ_92RS also measured the intake port size on 193 swirl port heads and also got 168 cc, just like Dyno Don.

And FWIW stock Vortecs are approx 170 cc (per CHP data, among many other sources). So there isn't much difference in the intake port volume of a 193 swirl port head casting (stock or ported), and a Vortec L31 head.... except in the mind of GOY.

I'd expect some casting volume variability, +/- 2 cc, but it doesn't much matter because ALL the intake runners are still considered small volume. And the ramp in a swirl port head isn't removed during porting -- the sharp (leading) edge is ground into a round -- so there is metal removal, but not nearly as much as the doomsayers would like to believe.

CrazyHawaiian

Bringing this back from the dead. The reason I lost interest in this post is because the 92 RS we were doing ended up being a complete POS with a blown trans among other problems, we actually lost interest in the project and its currently being parted out. Wish I had checked the car out better before starting the thread.

Yesterday I got my hands on a 91 RS that has a L03 w/ 110K and this one actually runs. So now its time to get to work!! I still have all the same parts I had before, plus now I have tuning tools.

Here's the list of everything I have for this build so far:
---------------------
Extra L03 w/ extra 187 Heads and Intake
Stock L98 cam from an 89 L98
Hedman 1 and 5/8ths Shorty Headers
Full 3" Exhaust with a Flowmaster 80 Series Muffler
9 bolt w/ 3.27's and POSI and Disc Brakes

Where would you guys go from here?

kdrolt

Port the heads.
Stamped self-aligning 1.6 rockers (if the budget allows).
Replace rotators on the exh valve with regular retainers/locks from the old engine --- and get new valvesprings.
ECM tuning.

DM91RS

Sorry if I missed it but is this an auto trans? I had a 3.23 rear with an LO3 auto in my first RS with al your planned mods except cam and it ran decent. (compared to stock that is )

DM

robertfrank

iTrader: (27)

If I ever got my hands on another L03 car and just wanted to boost the performance on the cheap all I would do is....

081 heads with light porting on the exhaust and a valve job
L98 cam
3.42 posi
350 manifolds and L69 y-pipe with a lowcost catback
and of course tune it

That would be about it.to me that would get an honest 200 or a little better HP to the ground and not be to aggressive.Good for a daily driver.

CrazyHawaiian

What would you guys do with the Intake? Port a stock one or do the carb manifold with the adapter? I'd planned to go to an open element filter, and considered a spacer. Gonna be selling that Air-Gap so I'll have $$ to buy another manifold.

Another question, would it be worth it to spend the $99 or whatever on a used LT1 cam instead of the L98 cam I already have? Upgrading the injectors will be a must?

RBob

iTrader: (1)

For a performance engine I prefer a carb intake with an adaptor.

As for an LT1 cam vs an L98 cam, it depends upon which one of each is being compared. The catch about LT1's is that they came in Caddy's, Caprice's, Camaro's, Firebird's, and Corvette's. So saying 'an LT1 cam' leaves a lot open as to what the specs are.

The L98 cams also vary.

Injectors: for a moderate build up a good fuel pump and an adjustable FPR will cover it. The stock 305 55#/hr injectors at 30 psi is good for a little over 300 HP (flywheel).

RBob.

TierAngst

The LT1 cam I was told to get if I went that route was a 95 F-body cam, you can usually get those for about $50 shipped.

BMmonteSS

I picked my LT1 cam for 30$ with lifters and all the roller hardware, there are alwasy 2 or 3 in the classifieds on this site.

DM91RS

Bob.........is this a direct comparison or a personal preference?

DM

CrazyHawaiian

Well, I've been doing minor work on this L03 ghetto bomber project, just the basic service stuff right now. Changed the oil/filter, changed the plugs, wires, cap, rotor. Changed the 02 sensor. Changed the transmission fluid/filter.

Here is probably less than 170hp at the crank, but it still goes!!



Also did some other stuff for my "application" here, installed some new rear shocks, progressive rate springs in the rear, gutted the Interior, changed the wheel/tire setup front/rear. Next mods coming up are front suspension and agressive alignment, and I gotta do something about the rearend open differential (decided to keep this rear in the car).

But getting back to the topic of power, my plans changed a little bit, decided I don't wanna get too crazy with the mods, so not sure if I wanna take the heads off (which I know will limit me). Also, decided I need to keep the exhaust as quiet as possible, so stock exhaust will stay (which also holds me back). After reading through this a couple times I've decided there are a few mods I'm definately going to do. The AFPR is one of them. So is the cam swap and DIY re-tune. Also decided to go the carb manifold/adapter route.

Here's some questions though:

1. Are the L98 350 stock exhaust manifolds actually better than the stock L03 exhaust manifolds?
2. Would the L98 cam from an 89 IROC-Z L98 be a worthwhile mod if I did 1.6 RR's at the same time? Or should I just go straight to some form of LT1 cam?
3. What is the cheapest carb manifold that will work with the least ammount of fitment issues?
4. What open element setup has the most hood clearance and least ammount of fitment issues?

If I should be searching instead of asking let me know, I did some minor research, could do more. THANK YOU FOR THE HELP GUYS!!!

TierAngst

What I would do and this is just me but
1. not sure on this one
2. Go with the LT1 cam, preferably the Z28 and not the B-car like I said before I think it is from a 95 that is the best
3. keep the stock instake manifold, fast355 has done some comparisons and for lower rpm power the stock manifold actually makes more power than most carb manifolds
4. check out the stickies there are tons of threads with part numbers and all that about open elements, most of which you can pick up for around $40 at your local parts store.

Fast355

iTrader: (2)

1.)The TPI cars have bigger outlets to the manifolds and bigger head pipes to the cat. Alot of LB9/L98 cars have dual catalytic converters. The cat-back exhaust system is larger and freer flowing as well.

2.) The L98 cam actually has more duration than the LT1 cam, but has less lift. A L98 cam with 1.6:1 rockers can almost always fit with stock springs in the heads. I would recomeend a spring upgrade however. A LT1 cam with 1.6:1 rockers generally involves cutting the guide bosses down to retainer clearance. The earlier TPI cars have a hotter cam with a wider LSA. The later speed density ones have a milder cam with a narrower LSA.

3.) In my testing the stock intake has proven totally adequate for up to 270+ RWHP, not to say that a gain was not possible even then. I find that it is benificial to open up some plenum area between the two TBI bores, even on stock engines. I do it with a 1" thick open center TBI spacer. Others have modified the intake to achieve this. Single plain intakes are common as well.

CrazyHawaiian

Sweet, I happen to have extra L98 manifolds here, if I can get a gain and the noise level is the same then I'm gonna go for it. Sounds like the cam choice would depend on what rocker ratio I decide on, stock ratio good for LT1 cams, upgraded ratio good for the L98 cams.

So I guess the general consensus on the intake manifold is to stick with the stock one and use a spacer. Is there any other cheap/free mods that can be done with the stock manifold? That'll be good because I can sell this Edelbrock Carb manifold and use that money to buy springs and stuff for the cam swap (or the cam itself if I go LT1 type).

What would you guys do to the TBI itself? Would the Ultimate TBI mods be enough?

Fast355

iTrader: (2)

I end up not even doing the TBI mods anymore. I have a full intake setup, with a little tiny snorkel, stock TBI, 1" spacer, am making roughly 275 FWHP, and show 95KPA @ 4,500 rpm.

TierAngst

Didn't know that about the L98 cam