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82 monte 09-21-2008 07:17 PM

Building First Engine
I have a 350 out of 95 silverado TBI, I'm keeping the TBI,but how can get more hp out of the motor without having to changing throttles bodies out. I want about another 150 horse

j.d.brown.042964 09-21-2008 08:00 PM

The only ways you'll realize THAT size of an increase to that engine would be through: 1.Forced induction (blower or turbo), 2. Nitrous, or 3.Major buildup. {All of which would require redesigning the fuel delivery system to support the increased need for fuel.} Even adding a 150 shot of nitrous requires additional fuel. Remember that an engine is basically just an air pump, and to get more out of it you've either got to force more into it, increase its capacity, or spin it much faster -all of which require SOME level of supporting modifications to accomadate the increased power level that you are attempting to attain. The ThrottleBody Injection system (being a very basic and simple type of fuel injection) is not very supportive of tunability or high horsepower levels, although it usually works great for it's intended purpose for which it was designed; namely- to be a simple, REASONABLY accurate, and reliable fuel supply system for low-mid horsepower oem powerplants. If you are wanting a 400+ HP/TQ engine you'll need to go carb or MPFI and include the supporting hardware to efficiently utilize the burnable mixture being supplied, IF you want something that will last and be reliable. :sweat: While you could conceivably add a nitrous setup to that engine as it is, repeated usage of anything more than about a 50-75 shot would stress those stock internals to beyond their capabilities in a relatively short order. :smash: Basically said, you have an unrealistic expectation for that engine as it is presently configured. To get 150+ beyond stock HP/TQ will require extensive modifications unless you want to put a rod through the block with a one-pass 150 shot (which still would require additional fuel delivery anyway). Check out the articles on the knowledge base on this site and you can get some ideas. Good luck with whatever you decide.-Jim

82 monte 09-22-2008 07:08 PM

What would happen if i bored it out about 20 or 30 over, how much hp would that give and what would I have to do about my fuel delivery then

j.d.brown.042964 09-22-2008 09:16 PM

Overboring to +.030 would give you 5 more c.i. (355) but that alone would probably not render you more than 1-3 hp increase, and if the engine is in decent internal condition as it sits, would be a waste of money. First and foremost you must decide what you want this engine to be used for, meaning; what will it's application be? From there you can determine HOW you will need to build it (for lower rpm "torque-heavy" usage such as a mainly streetrod/heavier car or truck usage, for high-revving high-horsepower drag ONLY motor, etc..) If you can post what your intended usage and vehicle will be, from there many folks on this site can direct you toward the proper reference materials/articles to get you started in the right direction. While a 350 based engine is least expensive to build-up, it still costs serious money to begin getting up over a certain level due to the changes that are needed to obtain that level. Minor changes will cost less and render less results, while major changes will cost more and render more results. What exactly is it that you are seeking to accomplish? If you can answer that question then the great people on this site can help you along the whole path. As far as using the factory TBI system for a buildup, you probably can't expect to get much over the (approx.) 250-260 hp level. Please post for all of those of us whom would like to help you along, just what type of vehicle and it's intended usage will be, and from there you can get much help in determining what can be done/how you can accomplish it, and most importantly- what you can expect the approximate costs and difficulty level to be. -"Toss us a friggin bone here,eh?" -(Just kidding,but I've always loved that phrase) Anyway-please give us more info to help you.-Jim

82 monte 09-23-2008 12:01 AM

I am putting this motor n a 82 monte carlo. I want more hp. I dont mind changing out the stock TBI.

j.d.brown.042964 09-23-2008 12:22 AM

I would suggest that you spend some time looking over the knowledge base on this site to get some ideas, especially as it relates to how much money you will be willing to spend and how "street-friendly" you want this engine to be. Also keep in mind that other systems and components will need to be upgraded to handle increased power levels. (Hi-hp plus "stock" tranny or rearend = "BOOM") Seriously, you'll need to make a plan for what you want to achieve.(horsepower level, torque level, rpm range, how much reliability, timeframe for completion, etc...) Personally, I prefer old-school (carbueration, very little if any computerization, etc...,but that is because I'm not so great with computers...whereas someone whom is good with computer theory and application may be better-off with employing as much of the newer technologies as possible, so as to get maximum powergains and tunability from the level of technology that is available out there) Yes-I'm a dinosaur, but I like the K.I.S.S. (keep it simple,stupid) theory because it fits my comfort zone. I'm more at home with a Lapdance than a Laptop! Anyways... take some time to go thru the knowledge base and get some ideas of what fits your overall plans and budget/timeframe. There's a TON of good info in the kb and related tech.articles, but to make use of it you'll have to have a good plan, -just as if you were going to build a house. Best of luck and hope you find all the help you need. (Shouldn't be a problem on this site)-Jim.

82 monte 09-23-2008 06:56 AM

I did some research and that motor comes stock 200hp and 310lb torque.I want to add a 100 to each or close to that as possible. How can i achieve that and is it even possible. Also, what would I have to change out?

eatonde 09-23-2008 08:11 AM

where are you so far
Im doing a similar project right now, I'm working on an 82' cutlass supreme with a 355 sbc. I was ust wundering what the current status of the engine is. Is it still all together or is it taken apart, do you have the heads off yet, if so, what kinda pistons are in it. If they are dish tops, you will have a hard time getting 100 more horses outta them unless you find some really small chamber heads to boost your compression. Basically you possibilities are endless, It just depends on what you wanna do with it and how much you wanna spend. Like Jim said.

If its got flat tops in the short block, and you know the rotating assembly is good, I personally would leave the short block alone to keep the budget reasonable. you can get 300 HP outta that short block quite easily. Just get a decent cam and some good heads, intake, headers, and carb, and you should be atleast to 300, probably well over.

Check out this article, they basically started with a junkyard block, punched it .030 to a 355 and threw in some forged dual 2 valve relief pistons and managed to exceed 500 HP with the right combo.

Please correct me if i'm wrong, but that is a roller block right?? I'm not really familiar with the new ones my SBC's are all pre 86' so they are a little different. I'd say you could pretty easily go with one of the matched engine kits like the Holley systemax kit, edelbrock topend kit, brodix kit, dart kit, Im not sure if AFR has a kit or not, but i'd say anyof these kits will put you well over 300 HP with flat tops with 64cc heads. You could always have someone help you match your own kit also, but these are dyno tested HP/TQ why guess if you don't hafta. Please provide more info when you can, and be sure to read that article, Its very interesting, to know that you can add 250 HP with a comp XE294 and some AFR 195's CNCed.

OHD 09-23-2008 08:49 AM

Do a google search on the specs for an origional lt1 350 (350/370HP)chev engine from the 70.

It will show you how much you would have to change to get your goals. EVERYTHING

It would probably be way cheaper to buy a crate engine than to change all your parts out.

eatonde 09-23-2008 09:31 AM

crate engine???????
first off that just takes all the fun and pride out of it... If your like me at all, you enjoy having the satisfaction of saying yea, "i did that". Anyone can go buy something from a book and call it quits, but the real pleasure comes when you beat the guys who got his from book with something you transformed with your own two hands.

second off there is no need for a crate engine if hes got a good short block. Even if he's gotta put a set of rings in it and bearings, hes lookin at $200-300 for a a block and rotating assembly thats perfectly fine up to 500HP. Even with dish tops he could still make it over 300 with out a doubt.

I tell you what I'm building, a 350 right now with a comp 280 magnum cam 480/480 lift, speed pro flat top hyper pistons, stock re furb crank, stck 5.7 rods, 10.45:1 CR with 58cc 305 HO headsgasket matched and bowl blended, 1.6 aluminum roller rockers, Edelbrock performer RPM dual plane intake, holley 750 carb, TH 350 stage 2 shift kit 3000 stall, 3.73 rear gears, 25-2800 lbs car. I've had 6 professional engine designers estimate that i'll have between 375-400 HP and 410 ft/lb TQ. I'll finish this engine for under $1000, and walk all over most crate motors that the average person can afford. Yes, its cause i already have most of the stuff sitting in my garage, but this is all stuff anyone can get very reasonable price, If you cant, I can, send me a PM. Just my 2 cents for what its worth.

OHD 09-23-2008 10:58 AM

"if hes got a good short block"

yup sometimes the devil is in the (small print or) details..........

get a nice cheap crate engine and go through it, there will be enough problems with one of them....then trying to turn a slug into a money pit.....

anyone can easily run up a 2K machine shop bill doing the rebuild/heavyup....

or just get a 350/370 from Jasper for less than you could ever do it....and have a warranty......

He will have enough issues uprading his drive train/trans/suspension/braking system to iron out when increasing his power level 50%.

PS: Danny we do have something in common, the NET lift on my cam is 485 485 116 lobe sep 278/292 duration....and I could not even get valve covers for 1000.00 :thumbup:

eatonde 09-23-2008 12:45 PM

$1000 valve covers????
LOL, thats kinda crazy, If you've got that in the valve covers you must have atleast 20K in the rest of it.

I wasn't trying to sound combative, but what i was trying to say is that If the Block, crank, pistons, and rods are all still together and were in excellent working order when removed from the silverado. Why not leave it together and use it the way it is if your on a budget. plus then you don't have all the machine shop work to be done. change the cam and through some good heads on it with a good intake and decent carb, and he'll be at or past his goal of 300. The holley systemax kit sells on summit for $1700 or $1800 on summit and it includes everything but the carb, and its advertised at over 400 HP. I don't think that its gaurentees to reach that amout but prolly pretty close, especially with flat tops.

j.d.brown.042964 09-23-2008 12:52 PM

If you really want to utilize that engine for buildup, there should be nothing wrong with doing so- IF and ONLY IF it can be determined that it's current internal condition is worth utilizing as a platform to build-up the topend. I didn't see any mention as to how many miles were on this unit, and it's service history. If it were @ 60k engine with all highway mileage and oil changes every 2K, has excellent oil pressure and good BALANCED compression readings across all cylinders, then I'd have no qualms about freshening up the topend with upgraded cam/headwork or aftermarket heads/timing chain and gears. On the flipside, if it was used in a delivery-vehicle application and spent most of it's life doing short trips and lots of idling, with oilchanges only every 5K, I'd want to either plan on finding a different platform to work from, or a MAJOR overhaul. SO...First things first. IF the engine's history is known good, then have the compression checked, leakdown test, and other BASIC checks to ascertain what it's internal health might be. From there you can make an informed decision on how to proceed further. One thing to consider is that the fuel system (Tank and Lines) in your '82 Monte were setup for a feedback type carbuerated application using no more than 5-7 psi obtained from a mechanical pump. Unless you want to upgrade fuel supply system this will preclude you from using TBI or MPFI on the Monte. Your 95 donor motor was a rollercam motor using an electric pump system and MAY not have a boss on the block or cam eccentric to drive a mechanical pump. This can be solved thru usage of an aftermarket (Holley or similar) electric pump and staying with a carbuerated induction system. The existing lines in the Monte weren't designed to handle the higher pressures used by fuel injection. These are some points to take into consideration. If you buildup a motor for that Monte plan on staying with a carbed motor (600-650 cfm vac. secondary or Q-jet), unless you want to dig deeper into the wallet and have more redesign issues to deal with. A nice portjob and freshening on those truck heads (or aftermarket if budget allows) + a nice (1500-5500 rpm) cam and intake, along with a decent exhaust system will get you where you want to be without too much drama. Be prepared of course to upgrade the trans somewhat (a freshening at the very LEAST) and cooling system as well. Keep researching this and other sites and you'll begin to develop an understanding of what's required to achieve your goals. DEFINITELY make sure that whatever you build from is in shape to begin building from, otherwise, as the others have said- "you'll end up with a MONEYPIT". Good luck with whatever way you decide to proceed, and keep us all informed with your progress. -Jim

eatonde 09-23-2008 02:12 PM

short block
yea, what he said. It all depends on how well you trully know the block and rotating assembly to decide whether its worth using. And as i said before i personally would go with flat top pistons for performance either way, unless you got some good 58-60cc heads to get your CR up. If you got the money go with forge if you change them, that will leave the nitrous option open for you down the road.

jimfulco 09-28-2008 02:29 AM

That 200hp rating is "net hp", rated with all accessories hooked up and a full stock factory exhaust system attached. Just freeing up the exhaust system ought to make a noticeable difference, but I don't see 350hp with the stock 350-sized TBI.

You should be able to make it with the bigger 454 injector body, which was adapted to a factory 4-bbl carb intake manifold by GM, but you'd still need more mods than that to get 350hp.

Some head mods, better yet new heads, and a cam change, and by now your computer's liable to be so confused it'd have to be modified to function with all the other stuff you changed.

It'd make a hell of a sleeper motor, though, once you got it all sorted out.

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