G-Body

iTrader: (4)

It finally hit me that the 91 was the first year of the newer rounded bodystyle. Yeah I guess hood height could be an issue.

If the intake is too tall to fit then the accys will have to be changed because the alternator sits higher than the top of the intake.

Before you buy truck exhaust manifolds you will want to try and measure to see if they will fit, the are a couple inches wider than the car exhaust on both sides. The f-body exhaust manifolds should bolt right onto the heads, they flow well, and are narrower.

kossuth

iTrader: (12)

I'm kinda jumping on a dead thread here but depending on the mounts that he uses, the truck manifolds will not fit. Been there tried that on the 95 that we converted. The cast fbody manifolds from 00+ will not work eithor. Your best bet if you get the mounts from Street and Performance is to get the headers from them as well. They have headers that are designed for this setup. You don't have to go that route, but just food for though

macs_forever

The thread's not totally dead. Thanks for the info. I'm VERY hesitant to notch the cross member for the sake of the exhaust manifolds. If only small cuts have to be made for the oil pan, I could buy a hand grinder and get the job done. I'm looking into a cowl induction hood that could provide a little more clearance up top, maybe I could elevate the engine slightly and avoid cutting the frame all together. The problem with that is it may cause clearance issues with the transmission. Given a choice, I'd rather modify the transmission tunnel than the frame. I've got a big "Dremel" like tool I could use to modify sheet metal. The more I think about it, I may be taking the body off the frame anyway and do a full ground up rebuild.

I'm also reconsidering a gen 1/2 engine instead. Pros of each as I understand it:

Gen 1 Pros:

• Past experience building these motors
• Uses original accessories
• could use original computer if upgrades are chosen carefully
• More of an incremental build. Some parts will work fine on my 305
• Less scrutiny from the emmisions testers
• Could add a turbo later to effectively increase compression ratio when running on E85.

Gen 1 Cons:

• Lower Compression Ratio required due to block first cooling
• Must retain smog pump and EGR valve
• Changing spark plugs continues to be a pain

Gen 1 Engine idea:

• World products iron block 4.155" bore
• L99 crankshaft 3.00" stroke
• 6.25" rods
• Pistons intended for use on a sbc 400cu engine with 6" rods
• 10:1 compression ratio
• comp cams XR252HR-10 high torque, high mileage cam
• comp cams 1.6 roller rockers
• GM Fast Burn aluminum heads
• LT1 (gen II) exhaust manifolds
• GM Vortec TBI intake manifold with bores drilled out to 2" for 454 tbi
• Stock or 454 TBI throttle body
• Stock HEI

Got to go for now. will post Gen 2 idea next

Horsepwraddict

iTrader: (12)

i dont understand your facination with short stroke motors. It just doesn't make sense with what your trying to do. Your using top of the line components and not taking advantage of them at all. With that stroke, your going to make no power with that cam and those heads. With the money you are throwing at this thing why not at least take a stock 350 block, maybe stroke it to a 383 and slap a roller cam in it. It will end up costing less for more power if you chose parts right. With that combo your just throwing money at something that isn't going to perform. All you would have to do to wake that combo up BIG TIME is throw a longer stroke in it. It would also save you from having to use an odd ball combonation of pistons/rods. It would make a torque monster out of that combo.

Even with a longer (im not talking huge, like a stock 350 cid 3.48" stroke) that cam is going to be a little anemic. Not to mention that cam isn't going to be to computer friendly when it comes to tuning, and its a solid roller, solids have come a long way since the old days as far as maintenance goes, but you still need to pay attention to it. I would go with a hydraulic roller.

macs_forever

as a ratio of bore to stroke, the 307 and 305 are "stroker" motors, and they suck. I suspect the secret to high torque is not in the stroke, but in the cubic inches and compression. I will admit that it is easier to get cubic inches and higher compression with a long stroke engine, but it is not impossible to do with a short stroke engine. I stated earlier in the thread, the short stroke is a byproduct of what I am interested in... large bores and long connecting rods.

All I have ever built are sbc 350s. If that is what I want, I have one setting in AZ complete with all the special goodies. I could have it shipped here. I want something different for this car. Did you read the article I mentioned ("The 350 Engine that Chevrolet should have built")? I'm not taking the article at face value, My father and many "old timers" had a special place in their heart for the 283 and 302 engines. My father's 1964 SS chevelle was actually faster with the 283 vs the 350 that he put in later.

At 300,000 miles, my first 350 flattened a lobe on the comp cams 268H cam. It was still faster than most production cars running on 7 cyls. I don't think I will get 300,000 miles out of a 383. More importantly, I don't think I can get good gas milage out of a 383. Cubic Inches must be feed. The more you have, the more fuel you consume all other things being equal. For economy, it is better to get more torque out of a smaller engine.

The cam I listed is a hydraulic roller. Here is the info:
Catalog page

• Operating range: 600-4600 (1.6 rockers should extend the top end a bit)
• Excellent milage, smooth idle (should work well with computer)
• 350+ft/lbs of torque in a 350 at 2000 rpm.

It's not a racing cam by any stretch, but it has the low end torque I'm looking for. I could take the next step up, but I would loose mileage I think. Also remember, the smaller the motor, the less cam you need. Compare the 252HR to the stock 305 cam:

• lift: .351/.386
• Duration: 180/196

Even this tiny cam is a great improvement. Again, the only reason I chose the smaller cam is for mpg. It doesn't loose much compared to the two next higher cams. Under hard acceleration, the caprice shifts into 3rd gear at 70-75 mph. I won't see 5000+ RPM for more than a few seconds unless I want to get above ~120 mph.

Horsepwraddict

iTrader: (12)

my bad about the cam, i didn't see the 'hr' at the end of it.

macs_forever

No problem at all. It's head scratching time now for me. I just visited my mechanic (The guy I go to for thinks I don't want to mess with like cv joints and fwd wheel bearings). The minivan has another wheel bearing going out. I saw an engine in the corner we had the following conversation:

me: What are you going to do with that?
him: I think I'm supposed to throw it in the trash, why, do you need any parts off of it?
me: I don't know, is it a baby LT1 or the 350 LT1
him: It came out of a Impala SS, I assume it's a 350. It has a bad rod knock
me: Don't throw it away, I'll take it if he doesn't want it.
him: OK, call me tomorrow, I'll talk to him and let you know.



So, (no help from the audience) do I put a 350 crank in it, or the 265 crank....

itslow

iTrader: (4)

If it's a LT1, leave it as a 350. If it's a L99, leave it in the corner.

Honestly, you won't like a Gen I/II SBC much smaller than that in a B-Body unless it's a "wild" one (which throws your fuel economy and tameness out the window). I speak from experience on that; I've got a '92 Wagon, '95 SS, and there are three more beyond that in my immediate family.

FWIW, the modified LS1 in my GTO gets the best mileage out of all my cars and it's the least tame engine. You can still pull out good mileage from a 346+ LSx and have better performance.

macs_forever

Engine acquired...350

itslow: What keeps going through my head is the fact that the 305 isn't that bad, it's just not enough. A 302 bored 020 is a 305. An LT1 based 305 with big bore, short stroke and 11:1 compression has got to be a significant improvement over the L03 no?

itslow

iTrader: (4)

Even with the higher compression, I surmise you'd find it not really all that great in a 4200+ pound car. The little guys worked well in 2800-3200 pound Muscle cars, but your car is nearly 1/3 heavier. Adjust accordingly.

There is a TON of info on the Impala SS Forum about making the LT1 perform well in these big cars. There are also some threads on putting the LT1 into the '91-93 cars; it's not quite a direct mechanical bolt-in deal (not including the wiring).

macs_forever

Thanks, I've been looking there.

Brought the engine home on Saturday, tore it down to the short block. The Mechanic said it had a bad rod knock, but everything turns smoothly with no "Clunk" sound coming from the rods as a move it back and forth. I did notice a couple of loose lifters and 1 loose spark plug. The crank and rods may be OK, but the chevy rods weigh over 600 grams for the 5.7" rod. I'm looking for longer, lighter rods.

Horsepwraddict

iTrader: (12)

if it has a bad rod you wont hear it without the engine running, their is no load to make it clunk, the only way to tell is to run it or pull the caps.

macs_forever

No problem, I'm tearing it completely down. I'm just glad that there are no "big surprises".

xBROKEx

iTrader: (7)

you wont get the mpg you want with an LT1, you're gonna way overbuild the engine and still DD the car, which also doesnt make alot of sense. You would have been better off goin with an older 350 than an LT1, optispark etc. This build doesnt make a whole lot of sense.

macs_forever

Hello... Thank you for coming, now... go away.

Poor guy, maybe I'd be an ignorant jerk if I had a job as an ANAList in Texas.

For the sake of everyone else, There is no advantage to going with an older 350. A gen I manifold can be used if desired. A gen I distributor can be used if desired. The only think really unique to the LT1 is the cooling system which is desireable. Heads can be a little expensive, so what? Great heads are expensive. It came with good heads. Can't say the same for the L05 or some of the other Gen I engines. If I wanted to, I could bolt on my old manifolds, distributor, and run the stock computer.

xBROKEx

iTrader: (7)

far from ignorant, and you spell analyst with a y. I know the general software engineer / programmer attitude is that they know more than everyone else on earth being that i work with many of these people on a daily basis im used to dealing with it. The fact that the goals you want don't seem to match the build you are doing. Lets go over what you are looking for


on a built engine in a 4200lb auto thats not realistic at all



with build numbers like this it sounds like you might be better off just buying a minivan


while this is great, this obviously will make your gas efficiency go down a bit, and being that the A/F ratio will need to be different on that type of fuel you will have to tune the car for one or the other.




if you can afford to do it right, why aren't you. Don't cheap out and get an LT1 block and drill it for gen I style distro. Either you have the money to do it right or you need a low budget build make up your mind.

macs_forever

Why does there have to be an idiot in every forum? The "i" vs the "y" was on purpose. A violinist plays a violin, you however are an analist. Playing the *** quite well. If you had comprehended the rest of the thread, you would have known why I backed off of my original plans of using a gen III motor. Go back and try again.

I've read some of your other comments. You sound exactly like the "you know more than anyone else" stereotype that you wish to project onto me. If I knew so much I would not have been asking questions of the friendlier folks here. Then you come along with your "doesn't make sense" crap. Go bug someone else. Your participation on this thread is neither required or desired.

xBROKEx

iTrader: (7)

just letting you know that what you want and what you are building are two different things, be my guest to spend the rest of your life in this fantasy world where 2 ton family cars with built engines and autos get 20mpg city.

hammertime

iTrader: (1)

An LT1 350 should meet your mileage requirement of 27 hwy /20 city, and at 260 hp stock, is far greater than your current 180hp / 225lb-ft. Headers and cold air could push that near 300 hp with the stock camshaft. While you may be able to get a custom cam ground to enhance the low end torque and throttle response, you probably won't make a lot more HP to remain true to your power from 800 - 3000 rpm goal.

Many builders have claimed that power comes from displacement, whether its long stroke, small bore or short stroke, large bore, the power made in the end will be the same. Basically, there may be little difference in power whether its done with 4.155 bore and 3.25 stroke, 4.00 bore and 3.48 stroke, or 3.85 bore and 3.75 stroke. If you are working on a budget, the least expensive route for you will be to use the most common components that will support your power level. Your goals truly require little in the way of performance parts. Stock or cast cranks will be fine, stock rods, or reconditioned stock rods will suffice, even cast or hypereutectic pistons will work well up to 400 hp. That said, spending your money on heads will get you the most bang for your buck. I would recommend something like these AFR LT1 180cc heads for the best power, along with the cam you specified earlier.

I read the article you linked many years ago, and thought the concept was a great idea. I thought that HOT ROD missed the ball on thier build though. That large bore really lent itself to larger valves, but they didn't run them. Also, to get 413 hp from those heads and that cam just doesn't seem to be all that much. It would however meet you power criteria, but I don't know if it could pull off the mileage. For comparisons sake, AFR 205 heads, a similar duration CheaTR cam (214/230 117+1) and stock iron manifolds were good for 395 RWHP in a small 3.90" bore, long 3.62" stroke 346 ci LS1.

I would never tell you not to do something different, as that is what keeps our hobby interesting. It certainly isn't the easy path though, and it seems you may be better served by rebuilding your newly aquired engine, and spending your money on the heads and cam to make your gains.

jmilz28

iTrader: (13)

Maybe I missed it, but you leave out a key component - BUDGET. You're a true engineer, aren't ya? hehe

Seriously, what is your budget, or at least a rough target? You have chosen the hard way with your engine choice. If you want to see it you can achieve your goals with old tech, just to prove a point - cool - but say it up front. Otherwise, it looks like you are saying one thing and doing another. You are being inconsistent and need to lay our your goals and requirements.

You do fit many stereotypes, including the one xBrokex mentions, and are rude, to boot. Quit being a butthead to people trying help you. Calling names too? You just proved how juvenile you are. The people here are trying to help you, have the knowledge and EXPERIENCE (which you admitted you DON'T) to help you, and you are acting like an jerk.

Your goals are tough, to say the least, and you are sh*ttiing on those trying to offer you effective advice because it's not what you want to hear. Trying to get a 4-5000lb sedan to get 20mpg city is not impossible, but it's close. Is that really your goal or is it to see how close you can get with 15 year old technology? Why not try it with the best out there. Start with a better baseline.

You need to learn some fundamentals, which the knowledgeable people here know. One, the bottom end doesn't make power (and efficiency), it only holds power (and efficiency). Obviously, assuming displacement is equal. There are efficiencies to be gained in the bottom end that will help, but you need to focus on heads/cam/valvetrain to get even close. Go talk to GTP/Craig, he's a wizard with LT engines. For LS engines, Tony Mamo may be your best bet to reach your magical 2 ton 20 mpg goal.

Your fascination with short stroke is only going to make it harder. Think of the early 70s Caddies that hit 20mpg with 500 cid motors. They did it because they had torque and gearing. They were idling around all the time at 60 mph, which is why they got "good" mileage.

Go with what is proven and try to improve that. If you're on a budget, go with a 5.7 gen III powertrain or 5.3 gen III from a truck. If not, hit the newer Trailblazer SS or Escalade drivelines. The gen II drivelines (I had one) are good and bulletproof, but have been improved on in every way, for less money.

I would bet you $$ on this: You will fail to meet your goals with an auto. Only a stick shift gives you a prayer with that 2 ton beauty.

The people in this forum can help you in ways your engineering degree can't, recognize that. These people have "been there and done that." Your insight will be able to help others too, don't blow the good will found here by being a jerk.

Tell us what your goals and requirements are so we can see how we can help. Drop your ego and insecurities or you'll hear crickets on here before long.