Getting ready to build my boosted 350. I'll be .030 over, and need to pick a good cam and piston. Leaning towards a cast piston and running with limited boost 6-8Lbs. I believe anything more will stress out the casting and cause premature failure (things go BOOM). Thinking of running a stock gs cam to get started. Vehicle is a 1976 Vega 2600 lbs (on an S-10 frame) 3.08 gears TH200R4 trans w/ 2200 converter 26" tires Hot air/blow thru set-up to start w/HEI. Eventually will have the SFI figured out and go that route. Turbo is from a '87 GN (still working on the pass side manifold) Any thoughts on this are welcome. Jim Goal is to get 30 mpg out of this set-up
Why risk it with cast pistons, go ahead and get some forged slugs for peice of mind and if you want to turn the boost up in the future or just the track you wont have to worry about it.
At $700 - $800 for just pistons, it kinda takes out my budget on just this one area of the build. Now if anyone has some good used forgings I'll like to know or any ideas on an appropriate SBC or SBF piston that would work. I'd just need to know the over bore & pin location. .030 is just a guess on available pistons. The 8.5 cr is most important using stock heads. Jim
Jim You are going to spend much more than $7-800 if you blow a cast piston . Save up until you can afford the good pistons , much cheaper in the long run. Just my 2 cents , but I do understand you wanting to chance it . Good Luck !
Mark has been running cast pistons with the twin turbos for a while now without issue. make sure you have a knock sensor hooked up and watch that air/fuel ratio like a hawk as well as the exhaust temps. Jetting the carb will be the key here to avoid detonation. Cheepest way to get a blowthrough setup going would be an edelbrock modded by Mark Burton and a tuning kit so you can fine tune it. In my opinion if you are going to spend the $ on a quickfuel or CSU carb you may as well go with MPFI or at least TBI due to the tuning advantages not to mension datalogging... I will be using multiport FI so I can tune the air/fuel curves timing ect ect and datalog the whole setup but it is $$$$ forsure. I think your ideas sound awesome and will work very well I am sure!
Sean, If I went the TBI route, can I get by with the Chevy 350 TBI unit? What other hardware am I going to need? Thinking about just getting a running 350 locally and running til I have problems under boost. That could give an inexpensive base line as to what is going to break using a stock set up. Jim
That is a great plan forsure, why not use a proven runner to get started if you are not ready to spend the bucks on the forged parts. Look for a 73-80 Buick 350 since they have the cap-screw type rods already. I would not run over 350 hp on the old style rods. Once you go forged pistons then you will want to go forged rods as well when boosting since it will be AWFULL tempting to turn the wick up in the boost department once you get things dialed in. If you make 350 hp NA then 500 hp is only about 5-6 psi away...Which is great except you will want to go closer to 10 psi and the stock rods will be a big question mark. A Quickfuel or CSU carb can be custom ordered for you combo and it will be a CLOSE tune forsure but if you change something in your combo and have to send it back for calibration you have downtime and extra cost again. These are $700-800 carbs. The Edelbrock converted to blowthrough by Mark Burton will be well under $500 with a tuning kit I am pretty sure so if you have the patients then go this route I suggest. Regarding the FI, I figuer I have over $2000 into my custom MPFI Intake, TB, 8 injectors, computer, sensors ect. I figuer if going to all this trouble you might as well go all out and go multiport FI vs TBI Info from Jeramie regarding an TBI on Buick 350: "If you have decent wiring skills and want to try something different, what about EFI. Before you say it will cost an arm and two legs just hear me out. 4 barrel ~750 cfm TBI that will accept standard bosch injectors-345.00. This includes the TPS, fuel rails, and regulator, all you need to supply is the injectors. (http://www.auto-nomics.com/cgi-bin/s...part=12168-001) Next is EFI computer, I highly recommend the Megasquirt II. I feel this is one of the best EFI computers on the market for the price. It has many features (some not found on unit 4 times it's price) and is starting to become user friendly. That and it seems like every month they are coming out with upgraded firmware for new features, which is free to download and use. For more info go to www.msefi.com and check around. Megasquirt II-250 (unassembled), 410 assembled from different places on the net (but i could cut you a get deal you couldn't pass up since you are an SE michigan buick guy ). Now on to the injectors. You can use some 160# injectors, this would be like having 8 80# injectors. I see ebay has some for 58.00 a piece. 4 160# injectors-232.00 In order to tune the car we are going to need some kind of O2 feedback. I'd suggest an LC-1 wideband for 199.00. This is a great O2 for the price and would be perfect for Megasquirt. It's also a great tool to use when tuning a carb. Wideband O2-199.00 Now it's time to visit your favorite junkyard. We need a coolant temp sensor and connector, intake air temp sensor and connector, 4 injector pigtails, 80's Chevy EFI distributor, and a Buick HEI dist. This could be anywhere from free to say 60.00. Lets get some spark to the engine. Now that you got the 80"s Chevy EFI dist and a Buick HEI from the junkyard we can now swap internals to make a Buick 7-pin HEI dist that can be computer controlled. Now we can control timing from the Megasquirt to what ever you want, when ever you want, and how you want it. Last but not least is the fuel supply. An aeromotive A1000 will do just fine for 295.98 and to filter an aeromotive 100 micron filter will do good for 89.88. Then you'd need some fuel tubing which depending on what you want could be from 25-30.00. So for a grand total of ~1500.00 you can have a stand alone EFI system. This is assuming that most stuff is new, if you find deals or buy some used parts you could probably do it for under a grand." Jeramie I assemble Megasquirt Computers PM or E-mail for details rdj5905@aol.com Currently Helping Sean Buick76
Re-reading about your budget, toss the TBI idea for now. Get started with a carb forsure. Regarding wanting to findout the week link in a boosted 350 the trial and error has already been done by others. The Connecting rods are the week link above about 650 hp (and that is with arp bolts and pollished beams). There is no absolute max number on these rods but of all the racing 350s that I have researched, almost all issues have been due to rod failures. The block and stock crank are both up to the task but lighter stronger forged rods and pistons will sure make me feel better when the boost gets up close to 10 psi... I plan to run this thing for a long time, so might as well do it once and do it right. I had my 398 hp engine with the 8:1 TRW forged pistons torn back down so we can add the HERCHE performance rods which are 90 grams lighter than stock and WAY stronger. Reballancing the bottom end of course...
Sean, Already knew about the rods! So I tossed mine on the teardown p Realistic budget to get me going is in the $1500 range (know anyone needing a 454 BBC?). This should get me a running 350sbb from a '70-80 Century, thus netting the rods & HEI. Think I'll start by boxing up the turbo stuff & just get this moving under its own power again. Moving forward..... A well tuned Q-Jet & TH200R4 will get me the desired mpg (25-30) & I can leave the 4wd Astro at home (weather permitting). I will need to figure out how to drop the engine lower in the mounts (see V8monza.com for pic's). Maybe Skyman can give me an idea or two. Jim
