stupid4901

iTrader: (3)

I have an 87 5.0L formula with a carb and desperately need more power. I was wondering the top potential would be either with a sc, turbos, nitrous, or a combination. what are the best combinations for this, and it has to be street acceptable, not necessarily comfortable.

87WS6

iTrader: (1)

A 305 is going to cost you alot more to build up for less power than other more common engine designs. You can get alot of power out of them. But it's not really worth it.

I have decided to bail on my 305TPI and go with a 350 or 383. After doing the research I have found that the 305 isn't worth the effor to build up.

At the most without NOS, turbos or superchargers you can only expect around 340HP if you stroke it and bore it out.

I would however start with free mods and get the suspension stuff and basic things out of the way before getting to the engine swap.

Willie

iTrader: (1)

First and foremost, you must make a determination of what YOU want out of your car. If budget is a concern (it is with most of us), research the most cost effective means to achieve your goal.

Is it worth keeping your 305? That depends. Yes, the same mods that work on a 305 also works on a 350 with better gains. However, if you factor in the cost of a 350, it might be cheaper to keep the 305. There are far too many variables here to go into any detail, so I'll leave it here.


After doing the research I have found that the 305 isn't worth the effor to build up.

This is a personal choice. It's not mine, but thanks to this type of reasoning, which most people conclude, it makes me look extremely good with the results I'm getting with my 305.

My original goal was to get my 305 into the 12's. I knew I would need a power adder, but that was not a concern. I never dreamed I would be in the 11's (actually, I'm knocking on this door) with a daily-driven 305. With my latest mods since my last track outing, I should make 11's the next time out.


At the most without NOS, turbos or superchargers you can only expect around 340HP if you stroke it and bore it out.

Agreed. But it appears from the original question that supercharging may not be out of the question, so it's entirely valid to keep the 305.


I would however start with free mods and get the suspension stuff and basic things out of the way before getting to the engine swap.

Yep. The entire process it not cheap. Good luck!

87WS6

iTrader: (1)

Those are valid points. Why did you keep the 305 Willie? Was it to show that it could be done or did your research lead to to conclude that it would work for you?

Willie

iTrader: (1)

Why did you keep the 305 Willie? Was it to show that it could be done or did your research lead to to conclude that it would work for you?

Good questions. Five years ago when I bought my bone stock 305 IROC-Z, I set my goal to get into the 12's. The first thing I did was tune my 99k mile car and run it: 15.9's @ 82 mph. I knew at that time that it's possible to get an N/A 350 into the 12's. But I didn't know of anyone running a power added 305, much less a 305 TPI.

I've always been one not to follow the path of the masses, so I made a decision to keep the 305 and build it. I've never regretted my decision because I've more than achieved my goal. And ya know, it feels sooo good to whoop up on those LT1/LS1 boys with my "technologically-antequated, displacement-challenged 305!!

Willie

Timz2882

iTrader: (1)

theres a guy on here, his name is BADDEST305 and he's runnin 11.4 on a 150shot of nitrous. im tryin to follow what he's doin but kinda keepin mine more street friendly.

Willie

iTrader: (1)

theres a guy on here, his name is BADDEST305 and he's runnin 11.4 on a 150shot of nitrous.

I know of him. It's a beautiful white '91 Z28. He went to carb because he couldn't figure out why a "big" shot of nitrous wouldn't work on the TPI. Tim Burgess had already figured it out but we didn't know of Baddest until after he converted. So if you're talking about the fastest 305 TPI that's daily-driven and emissions-legal, it's Tim. He's the moderator of the Electronics board.

Willie

misterjuice

You'd be amaze what a 305 TPI can do......if you do it right, with the right parts. I'm quite happy with my boosted 305. I'm knocking on 400 rwhp on stock tuning, stock heads, stock cam, stock trans, and stock rear.

It's your car, do whatever makes you happy.

87WS6

iTrader: (1)

Well my goal is to get into the 12's. Eventually. I would love to whip up on LT1-LS1 cars. But I don't care to much how I get there.

The main reason I am going with a 350 is because I am going to build up the engine and keep driving my car. When I want to do the swap I'll park it make the change.

I considered doing the work on the 305. But after doing the research on that it seemed to be more within my technical skills to do a 350 rather than messing with N20 and power adders.

B4Ctom1

The big problem with 305's appears to be valve shrouding from the small cylinder bore. If a power adder is used to cram extra intake charge into the bores then it is still an engine with a 3.48" stroke obviously capable of alot and this offsets it's main failing. I have considered the implications of a 283 and a TPI myself. It shares a bore diameter but the smaller size requires even less air to achieve its median capability. so maybe even a stock TPI could flow enough air to meet its requirements up to 6000 rpm or so?

83 Crossfire TA

iTrader: (2)

Heh, out of curiosity, what was the problem (you can just point me at a thread if you know where it is, not really sure what to search for or where)?

83 Crossfire TA

iTrader: (2)

HP production is limited by what rpm your combination is designed to turn (the limitations of the bottom end, and the flow/timing of the top end).

It’s not that difficult to exceed 400hp with a 305 if you build things to turn past 6000rpm, which not many people do with 305’s. FWIW, if you put heads about the equivalent of vortec heads (even well ported 305 LG4/L69 heads, skip messing with the crappy TPI/TBI heads, including the vette heads), and a comparable intake, exhaust and cam, you should be able to rev to 6700+ and make roughly 450hp, and even a stock TPI intake will work well on a 305 to over 6K rpm. The secret is to build/choose parts for a 305 and not a 350. If you keep the valves at 1.94 and optimize for it’s limitations you’ll be much happier then if you approach it like you’re building a small 350.

FWIW, a 305’s smaller bore will be harder to get good breathing in, but that could be compensated with using more compression/cam timing to build more cylinder pressure, since a 305’s smaller bore will also make it more detonation resistant and you will be able to better control and more quickly burn the complete intake charge, making for an overall more efficient engine (don’t believe me, look at the engine master’s challenge engines. This is something that I really think is a step in the right direction and considering conventional “hot rodding” thought, even I was surprised how almost all of them used bores smaller then 4” (stock 350) many starting with 307 or similar smaller bore blocks)

FWIW, the fastest NA, 305 TPI 3rd gen that I’ve seen is an NHRA stock car which runs in the mid to low 11’s.

Willie

iTrader: (1)

.... out of curiousity, what was the problem....

Although it was a simple matter of proper jetting. it was not simple to come to this conclusion. You see, Tim had the same problem for years. He could never get his 305 to run with jets larger than the 90hp pair. Once he built and installed (hard-wired) his wide-band O2 circuit, it became obvious that he was running way too rich, on the order of 9 to 1 A/F ratio. Once he determined the best jet sizes for a larger shot, he talked to CompuCar AND NO2 about his findings. They basically told him that they've done extensive research and that he was wrong. To that I say, a WB O2 does not lie, nor do his track times. I can only conclude that CompuCar and NO2 have tested 350's, not 305's.


....(even well ported 305 LG4/L69 heads, skip messing with the crappy TPI/TBI heads, including the vette heads)....

Tim runs ported STOCK heads, so I know these work. My personal experience is that I gained 0.8 seconds with ported Corvette heads and a Crane 2032 cam. When I swapped the heads for a pair of AFR 190's, I was more than disappointed -- absolutely no gain and a big hole in my wallet.


....even a stock TPI intake will work well on a 305 to over 6K rpm.

I don't have the stock TPI intake, but I can rev to over 6,200 rpm.


The secret is to build/choose parts for a 305 and not a 350. If you keep the valves at 1.94 and optimize for it’s limitations you’ll be much happier then if you approach it like you’re building a small 350.

I use 1.94/1.55 valves and the top lip of the cylinder bores on the intake side have been chamfered to decrease shrouding.


....that could be compensated with using more compression/cam timing to build more cylinder pressure....

Exactly. 9.2 C.R and 38 degrees of advance with 14-psig boost and 91 octane gas in my case.

Willie

SATURN5

So far I am happy with the 305 in the Bu..

mild cam.. rest is stock. I'm sure she won't last long with 14 lbs boost.. and the oil pressure is lower than I like. Who knows.. I might just stick with it over a 350..

this has been a rather interesting thread.. thanks guys.

Bob

side note.. I would think the additional area between the pistons would also seal better against a blown HG.

83 Crossfire TA

iTrader: (2)

Heh… naw, that’s not it. As per their #’s, he was running LEAN. Most N2O companies know that you can make more power by running smaller fuel jets with their setups, as a matter of fact I’ve purposely run the 100hp fuel jet with a 150hp N2O jet on my NX setup. What’s happening is that the manufacturer is playing it safe. They know that you can have all sorts of distribution problems and you’re asking for the fuel system to deliver significantly more fuel and that most people will not notice that their fuel pressure is dropping… (most people don’t even have a guage to tell), so to be safe and not become known as the “N2O company that blows up your engine” they purposely supply you with jets that will result in roughly a 6:1 A/F…

Heh… another one… that’s what I’VE BEEN TELLING PEOPLE FOR YEARS, and usually get some BS back like “you don’t understand VE” or some other crap.

What’s happening is that you’re hitting the classic wall, heads that are too big for the engine. If the heads flow more then what the swept volume of the engine is x maximum rpm (in other words, 100% ve at whatever rpm you’re turning to). EX, with a 305, if you’re only revving to 6500rpm, at 100% VE you’ll only be moving 574cfm, which works out to be about 209cfm/port. It’s doubtfull that the engine will try to use more then 100% VE at that rpm UNLESS the rest of the combination is setup to rev to say 7500-8000rpm.

So, if you take your ported stock heads, or stock vortec heads that flow roughly 220-230cfm on the intake port off and slap on some AFR’s that flow 290cfm (slight exaggeration, but you get my point), the engine will make no more power. Worse, assuming that everything else will stay the same, you’ll loose responsiveness and midrange because you just went from roughly 160cc intake ports to something in the 200cc range.

I’ve said it before, and I’ll say it again, most ‘enthusiasts’ and even professional shops run heads that are too big for the application in the thought that they’ll help.

The reason that I’m saying skip the TPI heads is that usually you can get the early ‘80’s 305 heads for less (usually free. I know of a shop that throws away complete 305’s, you can just pick them up if you want them), and it will take much less work to get something that workes really well, that they’re better designed heads for making a bit of power on these engines (some of them have chambers fairly similar to the newer ‘fastburn’ chambers, and all of them flow roughly 15-25cfm more stock then the later L98 heads, even the ‘vette heads)

That’s one way… of course, there isn’t much of a reason to run valves bigger then 1.94/1.5 on a 305 unless you’re planning on turning more then 7000rpm. BTW, another not so popular thing that I’ll tell people is that in almost all cases we run exhaust valves that are too large for the application. There are gains to be had in significantly higher exhaust port speeds then intake port speeds.

87WS6

iTrader: (1)

Well you guys have given me alot to think about. I have a low miles 305 that runs pretty damn good. It would be nice to not worry about shipping in an engine and not have to worry about discarding one.

Something for me to consider doing. I've got a perfectly good 305 block and if my goals can be accomplished without the replacement of the 305 and the added cost of getting another short block it just might fit the bill.

Willie

iTrader: (1)

Heh… naw, that’s not it. As per their #’s, he was running LEAN.

Can't quite agree here. The CompuCar's 150hp jets are 0.076 and 0.059. Tim had to reduce the fuel jet size down to a 0.038 while retaining the 0.076 nitrous jet to achieve 12.8 to 1 A/F. Doesn't this mean he was running very RICH with the 0.076 / 0.059?


What’s happening is that you’re hitting the classic wall, heads that are too big for the engine.

Agreed. But I could only compare results of the two heads up to 10-psig boost. That was the maximum boost level I took the Corvette heads to. At higher values, it's impossible for anyone to say one way or another. Be that as it may, I'm glad I went with the AFR's only because of the much thicker deck height.

Willie

83 Crossfire TA

iTrader: (2)

I’m not sure that I see a problem. Whipping out the calculator, assuming that that .059 jet was 6:1, the .038 should be about 14:1. Assuming that you didn’t have any detonation, it is reasonable to expect that you saw best power there, but I would suggest that the car was right at the ragged edge of what you could get away with. If your NA A/F was relatively rich, say about 12:1, that would put your mixture at about 12.5-13:1 (depending on how much HP the engine makes NA) which assuming that you’re not battling detonation and getting a good distribution should be a really sweet place to be. Same deal if you’re running more then the stock fuel pressure, about 47-49psi would bring that back down to under 13:1, and again, you’re good.

You’re limitation isn’t the boost, If you’re not spinning any more RPM then it doesn’t make a difference what boost you push through it, you’re going to see the same power between the 2 heads. About the only thing that I could think of that would have given you more power without other changes (like a different cam that would have optimized your setup for a higher rpm) would be if you ran iron heads (which would probably be as strong as the thicker decked AFR’s) or heads with a coated chamber (pretty much the same effect as going with iron heads), both of which would have retained more of the heat of combustion in the chamber harnessing slightly more power. But with either of those you might have found yourself having to run race gas to control detonation at higher boosts (unless you got really good at massaging the stock chambers and started with just the right head).

To take advantage about of what is really better about the AFR heads you’ll really either need to turn more rpm or put them on a larger engine. But yea, I agree, the AFR’s should be significantly more durable then the L98 ‘vette heads.

Willie

iTrader: (1)

I’m not sure that I see a problem. Whipping out the calculator, assuming that that .059 jet was 6:1, the .038 should be about 14:1.

I don't doubt the calculations at all. I believe that NOS and CompuCar was on the same track as you, but the problem was that with the 0.076/0.059 combo, his car sputtered and ran awful. The WB showed ~9:1 A/F ratio. So for whatever unexplainable (by calculations) reasons, Tim's 305 ran the best with the 0.038 fuel jet. Note: He runs 54-psig base fuel pressure, but I believe it drops slightly with the nitrous engaged.


You’re limitation isn’t the boost, If you’re not spinning any more RPM then it doesn’t make a difference what boost you push through it, you’re going to see the same power between the 2 heads.

I appreciate the info as I wasn't sure about this. However, I was spinning the engine to 5,200 rpms when I was making 10-psig. I'm now between 6,000 - 6,200 rpms.

Willie

83 Crossfire TA

iTrader: (2)

Perfect, and about what I expected. So with the factory jetting you were getting about 5:1 A/F and you went to about 12:1.

Now average that original 5:1 with your NA a/f ratio (well proportionate amounts, ex, if the engine is making 300hp NA at about 12.5:1 and you added 150hp at 5:1 you’d end up with roughly 9:1 for the whole thing), and that 9:1 was rich enough that it didn’t want to burn or run right.

Now lets say that you’re still making 300hp at 12.5:1 na, and used your jetting to get 150hp 12:1, you’re at a little over 12.3:1, which will run great.

I suspect that the problem with the factory jetting was a combination of it being on a 305 so any A/F ratio changes effected the overall much more, and the fact that you were getting about 13% more fuel with that jetting then the factory was expecting because of the 54psi.

Well… so the question would be how much did your ported L98 heads flow? Stock ones should allow for about 5500rpm on a 305 without any real restriction, If they flow roughly 25cfm over stock at a reasonable lift (about 200cfm at .400-.450) then they would work find to 6200-6500rpm.

Sorry if I’m overanalyzing the “problem” but it’s one of those, “I can’t build every possible combination so I like to be able to determine what’s happening if I can...” thing

bluehog67

I heard it's not to advisable to beef up a 305 because the tranny can't take much more than the stock 170-200 horses. and especially if you have 5 speed, the clutch needs to be replace by a racing clutch. Plus to really get all the horse power to the road you'd need a posi rear end. So i believe it's a waste of time to beefup a 305. I'm dumpin mine for an LT1, or maybe a 454, cause I can get my hands on a big block for pretty cheap from my buddy.

83 Crossfire TA

iTrader: (2)

Well, that’s somewhat retarded reasoning. An SBC is an SBC, there isn’t that much difference between a 305 and 350, and they bolt to the same transmissions. They both came from the factory with the same TH700R4 bolted to them, and yea, the T5 is pretty much a piece of junk, which is why you couldn’t get it behind an L98 from the factory.

So it makes no sense to hop up a 305 because it will blow up the tranny, but it makes sense to bolt up a 350/LT1/big block, which will blow up the tranny faster (torque is what breaks driveline parts and torque is always proportionate to displacement).

FWIW, if someone cared to test it I’d bet that you can go faster with a T5 behind a 305 then a 350, just because the 305 that makes the same power will make it at a higher rpm and lower torque so you’ll still run the time before you blow up the tranny.

bluehog67

http://search.barnesandnoble.com/boo...030436X&itm=16

That's what this book says that the 305 tranny can't handle a hopped up 305 nor a 350. I said I just HEARD that, it's in very specific detail in this book.

Buy and Read

SATURN5

Torque along with traction... is what breaks parts. Torque alone will just spin the wheels. Now bolt on some slicks.... bang. <G>

83 Crossfire TA

iTrader: (2)

You either misread it or it's wrong. Actually, let me rephrase that... what you're saying makes no sence and I'm fairly certine that that is not the suggestion that was in that book.

A T5 won't hold the power that a healthy 305 will put out with traction (good point, saturn5), not really much of a point arguing that, driven hard it will blow up with just about any healthy engine in front of it, it's weaker sauce then the 10 bolt rear. The 700r4 is the same one that was put behind the 350 and with minor changes and a rename to a 4l60 behind the LT1.

I fail to see how putting a big block in front of either will make it stronger (the reason you gave the transimssion will blow up so there's no point in upgrading the 305, you might as well put a big block in).

bluehog67

'83 Crossfire T/A -

I never said I was going to keep the tranny. I'm junkin it when I get the Big Block.

oh and for the record :

And I quote Jason Scott's Book "HOW TO TUNE AND MODIFY YOUR CAMARO 1982-1998" page 69 (no joke here) insert on the bottom right

" 'THE 305 vs. 350 Engine Debate'
'The Problem can seem pretty perplexing at 1st. But when you start thinking about it, the answer becomes clear-the 350 is the way to go! The 305 only limits the amount of power you are able to produce, given that the bulk of the parts you are going to stuff into the 305 would work even better in the 350.

'Even if you want a manual tranny, it doesn't make much sense to go with the 305. The stock MM5 Borg-Warner T5 5-speed manual gearbox CAN'T HANDLE THE STOCK 350'S POWER AND SURELY BREAKS UP WHEN MATED TO A HOPPED-UP 305.'

'The reality is you need to replace a hefty hunk of the drivetrain even if you stick with the undercubed 305. Then you might as well just go for the 350 and get all the power you can. Besides, it's no more difficult - or costly - to rebuild the drivetrain to handle the 350's output than it is to set it up for the 305's '

'In short, cubes count, and the more the merrier' "

If you want me to I can scan the page and everything for you.

daverr

iTrader: (1)

correct me if im wrong but if u had heads that flowed 200 cfm wouldnt your potential rpm be higher than 6500rpm.im trying to figure out how u came up with that figure.
i used 100% for ve
305 reving at 6500 will move about 573cfm of air

573/4= 143 cfm flow at the ports at 6500 rpm.
now if a head flows 200 cfm , it would be able to support 9000 rpms.mathematically speaking of courseand.of course this not entirely possible cause the valve gradually opens not instant.
so if use a big cam i say u could get the motor over 6500 rpms easy.

83 Crossfire TA

iTrader: (2)

Sure, those kind of #’s would be fine if the valve was open all the time and the runner didn’t have to complete with 7 other runners that might have an overlapping valve timing event.

I got the #’s by comparing the results from known combinations that were dyno tested with published VE #’s. I believe that one of the head manufacturers has a rule of thumb for how much port flow you need to support a specific HP that last I checked came up with similar numbers.

TwiztedZ28

I just wanted to add that I have a 87 tpi 305 in an iroc and
A. it will walk all over a stock or very mildly modded tpi 350 (my 305 has an exhaust and headers as well as k&n's thats basically it)
B. The T-5 in it is what makes it move so well. And it seems to hold up very well. Ive pounded on it time and time again and no problems after 3 years. Also its running a consistant 14.2 with no suspension mods at all...so i have to vote for this guy to work on his 305.... research it and do it right and he'll get there....hey the 302 mustangs can do it (just alittle cheaper)

stupid4901

iTrader: (3)

I am very happy to see all these responses and had no idea the 305 had such potential. Now that I have decided to keep it where's a good place to start. I have a 14x3 K&N and the rest is stock. I'm looking for decent fuel economy and power and some good street manners. Should i change to tpi, a new exhaust, a cam, port heads? What's best?

83 Crossfire TA

iTrader: (2)

That depends on what 305 you have. I’m assuming based on what you’ve said that it’s either an early carbed 305 (LG4 or L69), or a later TBI car (LO3). In all cases I’d start with headers (personal favorite on these cars, the headman ¾ length or shorties (they’re longer then normal shorties), and a reasonable exhaust (high flow cat(s) or remove the cat, 2.75” or larger intermediate pipe and a good muffler, my choice is an ultraflow welded).

From there depends ho what weaknesses you’re dealing with. EX, on an LO3 I’d put some better heads on next. On the earlier carbed cars, the heads are about as good as anything used on a 3rd gen v8, and I’d do a cam next there…

stupid4901

iTrader: (3)

yeah i have the lg4. Are the hookers better then the heddmans and what cam should i get and what do i need to put it in?

BADDEST305

i must agree that the 305 has potenial
i did mine just to be different and to see what i could get a 305 to go, but if you have access to a 350 to do i'd go that route cause i'd be in the 10's if i did! but i loves my 305

83 Crossfire TA

iTrader: (2)

The hooker and headman sorties are very comparable. Both are what I call ¾ length which will fatten up your midrange while helping top end. I like the headman’s better, mostly for the reason that they’re cheaper and I think that the driver’s side header exits at a better angle. When I installed them there was no y-pipe for either, so I made my own, but there is a y available for both now, as well as versions with emissions goodies… As an alternative, full length headers will help that midrange out even a little more if you’re willing to deal with the ground clearance issues and know someone to make you a custom y-pipe. In that case you want the headman ones, since they have 1-5/8” primaries (don’t go bigger then that on anything but the most serious 305).

If you want them to look good for more then a couple of weeks I’d get them coated, but I’ve got a set of headmans that I welded an O2 bung… (before the emissions stuff was available) that are still fine, just look crusty after 12 years that were never coated.

Depending on what you plan on doing with the rest of the exhaust, a cheap way to get some thing that works well is to just snag a full exhaust that someone cut off of an LT1/LS1 car. They flow well (I’ve run 119mph though the stock exhaust on my ’97), and you can get them cheap/free usually.

From there on the LG4 I’d probably consider doing something with the cam (the carb engines are much more tolerant of big cams then FI, but I would still probably go with something roughly sized like the stock LT1 cam, or maybe a little bigger), possibly an aftermarket intake (performer air gap), and if it was my car I’d pull the heads, clean them up and reinstall them with much thinner head gaskets (better quench/compression)

mikobu3

reading all your posts on the 305 makes we wonder here???

i got a stock original 86 305tpi in my ta , its only got 24,000 miles on it , now i want to spend a little money on the car to wake it up a little, here are a list of things i want to do

1 vortec heads ?
2 COMP CAM 212 -218 449 456 112LSA
3 BIGGER STALL
4 HEADERS
5 PROM TUNING

i already have 3.42 gears , i also have good ignition system, airfoil,

how would my 86 305tpi go with vortec heads, and that comp cam, i no i will need that vortec base for tpi,
thanks

ThirdGenCamaroZ

Are you people dumb? Saying that you can only make 340 hp 305 N.A. This is bull$#@% look at this link and grow a brain. And for the guy who posted this whole message, KEEP THE 305 make this motor then hit it with a 150 shot (of nos that is) and say good bye to 15 sec 1\4 slips and hello to 11s or 10.9s slips! And please stop saying a 350 is better guys its only 45ci more! Plus a 305 last longer because of less stroke! Wow how ask any one about how long stroker motors last (and yes a 350 is a stroker motor!) And to top that all off you get better gas mileage then a 350 with the same kinda mods! I had to put that last part in for every time I've heard some one say 305 is a ****ty motor and to swap it with a 350!!!!

O yea here is that link:
http://www.hioutput.com/tech/400hp/400hp.html



____________________________________________________

'85 IROC-Z
305 H.O. Motor
T-5 5 Spd.
Weiand stealth intake manifold
Carter AFB Carb
Open element air cleaner

p.s. i havent made that motor yet, dont have the money

bigals87z28

That tranny question was retarted... the t-5 wont handle a 350's torque? i have see t-5 swaps into 350's and i have seen t-5's hold up to 400rwhp (misterjuices's iroc) His t-5 holds, by the skin of its teeth, but it holds. I dont advise that if you are gunna juice up any engine that you leave stock tranny there. The drivetrain has to be built for the engine, every gearhead knows that. there are 700r4 that are being built that will hold up to 450 hp-ft/lbs and the best part, is only a tad higher then getting your stock one rebuilt!! Next year i plan on getting a new tranny from TCI or BM or some shop so that i can one day just bolt up some big block hehehe. also if you are running more then 350 hp and your tranny is set, your rear is next to go... engine torque will find the weak point...

SATURN5

____________________________________________________


I hate to burst your bubble, but a 305 has the SAME stroke as a 350. They share the same crank, the rods are the same (305 rods in reality are thinner). The bore is smaller 3.78" vs. 4 inch. As far as a 350 being a stroker, than, that includes anything larger than the original 265 SBC.
Crank stroke
262ci / 3.100", 265ci / 3.000", 267ci / 3.484", 283ci / 3.000", 302ci / 3.000"
305ci / 3.484", 307ci / 3.250", 327ci / 3.250", 350ci / 3.484", 400ci / 3.750"

Granted not all those shown have 4 inch bores..

All in all if you have a good 305, fine, use it. If you have to build one, well.. a 350 is a smarter choice.

Oh.... I am running a 305...

chhers, BW

SATURN5

I disagree.. I have seen plenty of T-5's broken from 302's, 305's, and just about any healthy motor can break one. For street use, one may live for sometime, but take it to the track, bolt on some slicks and get back with me..

83 Crossfire TA

iTrader: (2)

I think that you need to assess your status based on that first question before posting anymore.

305- 3.48” stroke x 3.736” bore
350- 3.48” stroke x 4” bore

A 350 is a “stroker motor?” As compared to what? Not a 305 unless you believe that 3.48” > 3.48”

Second, stroking in and of it self does not hurt engine durability. There are some side effects from the way it is done in some cases that can, but a longer stroke in and of itself will not cause wear.

All that being said, I still believe that you can build a perfectly good engine out of a 305. As a matter of fact, in some ways it can be built better, but for the most part you have to realize that there are advantages and disadvantages on both sides and you have to evaluate them and choose accordingly.

bigals87z28

a 350 is a stroked 327. a 302 is a de-stroked 327... 305 was a bad idea!! should of just kept the 302. I would of given up low end torque, but by the time a TPI like system would be developed in th 80's, this would have already been planned for and i wouldnt be surprised if the TPI you see today would have looked like the intake on hte 5.0 stangs. Chevy dropping the 302 was a big mistake as we see 5.0 stangs that capitalized on it for many years... I plan on making my 305 run 13's NA, but as i do so i am building around my motor and working on the car itself, getting it ready for that one day when it gets a heart transplant.

83 Crossfire TA

iTrader: (2)

I’m not sure that I’m following your logic.

Bore/stroke has almost no inherent relationship to torque. Almost the only thing that has anything to do with torque is displacement and airflow. Rod/stroke ratio has a tiny little bit to do with torque production (actually, the transfer of power from the piston to the crank, which results in a slight increase), but if you do the math and figure it out, there is less then .02% to be gained in going from a 5.7” rod to a 6.125” rod. Really, from a power perspective, for smaller displacements we’d be better off with a shorter deck AND rod like the small block ford does (there’s 2 basic deck heights for the SBF, 351’s are built on a tall deck block and 302’s and smaller on a short deck). You’ll gain more from the decrease in reciprocating mass then you will in the loss of R/S geometry.

Have you messed with a stock SBF, fuel injected intake? The intake runners are almost as long and SMALLER then a TPI. Look at their hp/torque curves and compare them to a LB9, you’ll find that they’re very similar (most of the difference is in the crappy heads that ford used on them, which are actually significantly crappier then the chevy heads which is almost unbelieveable). The only real advantage to the ford intake is that it has better head port entry angles, and is easier to work on (fewer pieces), but otherwise the TPI beats it in most categories. The Ford has a serious problem with distribution which the TPI does not.

Chevy dropping the 302 (the only reason that it existed was to build a legal engine for a specific class of racing) and going with a 305 later made perfect sense at the time. It gave them a much more efficient package (compare gas mileages between mustangs and f-bodies, you’ll find that equally optioned f-bodies did much bigger dispite being heavier with larger tires/more rolling resistance), which gm they wasn’t able to reproduce on a 4” bore engine till the vortec/fastburn/LT* head design came out. Now on the LS* engines they've again gone with a smaller bore/stroke for the same reason that the 305 made sense (and the same reason that a bunch of the PHR engine master's competitors started with 307's rather then 350's)

The only advantage that a 4x3” (302) has over a 3.736x3.48” (305) engine is that the 4” bore has more room for larger valves without shrouding them, but of course, neither manufacturer used valves anywhere near the size that would cause that to be a problem. And actually, if you really want to get down to the finer points, when running a 1.96” valve with either engine, the ford head would flow less even with the larger bore because of the differences in the intake runner shapes in the 2 heads (again, assuming that you keep everything else even).

The only reason that the 5.0 thing took off like it did is that there was factory support (SVO, Ford Motorsport, SVT…) and the fact that it’s easier to work on things in the engine bay (you can do a set of fox mustang headers in under 1-1/2 hours, you can’t touch that on an f-body).

bigals87z28

83, im not knocking the 305 as i am trying to build a 13sec NA one, but everyone knows that making power is not what teh 305 was made for. If you want to go faster NA then 13's with anything, its gunna have to be of a bigger bore. 305s can be built to put out power, but the money you put into that 305 would be better used in a stroked 350 or greater. The 302's small stroke would not allow it to create a lot of torque and its powerband is at a level higher then what tpi likes to be at. Where a 302 would shine, like high rpms, tpi would choke it off. The mustang's can make a lot of power with minimal bolt ons and will blow the doors off a bolt on 305. I know the history of the 302 and why it went away, but the in the end the 302 would have made more power at across the board then the 305 does. TPI gives the 305 the superman-like torque, but only for a short time, where the 302's will keep pulling. You cant really compare the two types of engines on flow because the heads and block are totaly different. What you have to compare is a 302 vs a 305 sbc. 302's will make more power over the range and will go higher then a 305's. The 305 was made for the 70's to lower fuel consumtion, but keep some power. It worked, but by 87 the 305 should of went by the wayside.

ThirdGenCamaroZ

You all are a bunch of &$#@*&^T$%#%$# you people who say that stroke has nothing to do with TQ! LOL thats funny as &(#@! so why the hell is a 383 making so much TQ for ? And also the guy who said a 305 crank and a 350 crank is the same, umm NO that is a totally different crank. You can try to put 305 connecting rods on 350 crank with pistons and lets see if you'd have any clearance AT ALL. B4 you say any thing else GO READ A BOOK OR GET YOUR ASE.



____________________________________________________

'85 IROC-Z
305 H.O. Motor
T-5 5 Spd.
Weiand stealth intake manifold
Carter AFB Carb
Open element air cleaner

bigals87z28

AHAHAH! umm yea ok.. the 305 and the 350 BOTH share the same crank. Funny little guy aren't ya?

and I dont need to be ASE cert to read either.

SATURN5

Grow up... you said a 305 and a 350 have different strokes... They don't.
Is the crank the same? yes. is it interchangable? no.

305 rods are thinner as I said above.

Oh.. I got my ASE back in 87..

BW

bigals87z28

i thought i wrote about the rods being different?... oh well..

83 Crossfire TA

iTrader: (2)

Well, since you insist in making an *** of yourself:

The 305 and 350 cranks used through the ‘80’s and early 90’s have the same casting #, though one that was originally installed in a 305 will require a lot of weight added to make it balance with 350 pistons.

The rods are the same, though in ’89 they both got thinner, heavier and weaker rods.

Assuming that you balance them correctly you could use a 350 crank and rods in a 305 block with 305 pistons, you could also use a 305 crank and rods in a 350 block with 350 pistons. You could use stock 305 or 350 heads on any combination, but most 305’s came with ~58cc chambers and most 350’s came with ~64cc chambers (except the vettes which had 58cc chambers).

Again the STROKE is the same, the only real differences between the engines were the cylinder bore, pistons and chamber volume.

Maybe YOU should consider reading a book. If I were you I'd start with a few self help books and work on that attitude, then when you’ve got that in check and you have the self confidence that it won’t crush your psyche to be wrong I’d suggest one of the SBC “picture books” like Lingenfelter’s SBC book.

Yarnboy

I love this thread! Other people's ignorance is bliss.

WS6 Berlinetta

I'm contemplateing a few things for my 305 TBI daily driver. I want more power than the stock L03 and better gas mileage than the 360ci block in my '84.

I'm thinking about tweaking out the L03 for now I just got an LT1 cam and some other misc parts to throw in and I have a set of stock LG4 heads that were on my '84 before I got the 350 block. Would it be worth getting a porting kit and cleaning the castings up and polishing the combustion chambers and exhaust ports?

I'm also thinking about the next block once this 305 dies. I'm thinking 307, 327, or 350. The 350 is the default choice for the moment but I've been wondering about a 307 with it's larger bore shorter stoke compared to the 305's tight bore long stroke.

Any thoughts?

R