chevy1500z71

well to start off, i blew my motor to hell from all the boost and 200k miles finally, yes it was tuned very good, 13 pounds was just too much. anyway, i have a fairly low budget and want to get the best bang out of my buck and i have a few engines to pick from which i will describe in a second, all have hypereutectic pistons. so here are my plans, its gonna be a 383, and its gonna run 10pound of boost, dont care about a high rever, i want a torque monster, 5500rpms is about what i want. other than that, i dont care.

so here are my choices
383 stroker, from same year truck as mine blueprinted professionally done with vortec heads, cam specs are 480 lift on a 112 centerline, hypereutectic pistons, cast crank, 2 bolt main, comes with 8qt kick ou pan and high volume oil pump, flexplate, and balancer- 1700$, has 8000 miles on it.

next motor, brand new never used 383 4 bolt main, hypereutectic and cast guts, unknown(for now) heads with 3 angle valve job and springs, unknown(for now) cam specs, high volume oil pump, flex plate and balncer and all and this motor is pretty much a carb short of a turn key motor- 1900$ done by a machine shop, not a backyard build. but this one is an early block, where as the other is from the same year. both have flat tappets and im fine with that and dont ever plan on a roller, but what else does putting an early block in a truck that came with a later block include, not much id imagine.

i may be all over the place here but the main thing im concerned with is the topic of the thread, are hypereutectics good for boost? o yea, and the 2 bolt main motor id probably have drilled for a splayed 4 bolt cap. im aware that the 112 centerline isnt ideal for a blower, but i can tune, so it shouldnt be too much of an issue.

thanks for any help, and thanks for having the patients to get through my long boring post if you did.
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o yea, the 2 bolt motor is 9.6:1, and im sure the other one si in that ballpark as well. i have methanol injection and always run 93 octane...i know 8.5ish is ideal but i would think that id be fine with that compression ratio, feel free to tell me otherwise. i cant be too choosy with my lower budget.

online170

I dont run a boosted engine, nor have i ever built one.

But just going by what ive read, you always want forged for boost or nitrous.

Hypers wont be as strong as forged, and they may work, but forged is cheap insurance.

scribbles

Hypereutectic are strong but very brittle, the tinniest bit of detonation will kill them. I am not sure about the hp rating of the cast internals, but I would go with at least forged pistons. They will flex a tiny bit instead of cracking. With boost, moderate starting compression, and a heavy truck you will have some detonation even with the best tune.

85gulstrandTA

if you add splayed outer bolts you will need to take the block completely apart to have it honed after the new bolts are installed. if you are doing that add the forged pistons and rebalance, might as well add the cam that is designed for your set up. while you've taken it this far check the bearings and replace if needed.......where does it end right? if you know your running a set up that has a weakness stay well within the know weakness..2 ceants....MHO

scribbles

Did you crack your block? Why not rebuild it?

85gulstrandTA

Yea what he said, unless everything is destroyed, have you looked at it yet.
have the block cheched and get the whole rotating assmbly as a kit that's balanced and built to what you want it to be, IE:rpm range,use,blower,ect.

also i forgot to say on the last post why add splayed cap if you are not upgrading to forged pistons.....figure out what you need to do it right and then look for the parts. if you can get used parts from poeple you trust. drag racers tend to have good parts that have little use on them.

chevy1500z71

if non forged pistons are that week, how come iv yet to crack a stock 200,000 mile one yet? im not saying anyone here is wrong, your all right on the money, but just a little exagerted. the thing is, i can get that 2 bolt motor for 1400$, everythign short of the heads and re-use my heads with soem beter springs. i think it would be a very good low cost set up. reason i dont rebuild mine is because im in a pinch, i need this truck as my nyl means of transportation, im driving it around right now with smoke rolling out of the hood everywhere. im just getting so bad blow by the oil spews from the valve cover breathers like a garden hose even with strait 40 weight oil. and if i built mine it would be a backyard build vs a motor thats been blueprinted and built proffesionally.

so the question is, for 1400$, good deal, or bad deal?

o yea, and can you have your heads milled out to a larger cc for lower compression by an average machine shop?

also, this motor is from my year truck, so there will be no issues with things being different like i read there are issues with the timing cover and crank sensor and such if you use a pre 85 block.

WASyL

they are as week as week was the engine finetune with computer, if you keep your AFR and EGT at proper level there will be no knocking or other problems up to some level, as i recon L98 with stock CR should handle up to 14-16 PSI with good tuning and keeping EGT at about 900C maximum

chevy1500z71

i dont have an egt guage, i do have a wideband and guage so i always keep my air fuel good, i like it to be aorund 11.5:1 under boost and my timingis pretty mild, at wot its only 2 degrees more than stock timing and i spray methanol. is it important to have an egt guage?

is the bottom end an issue, is a 2 bolt that good?

junkcltr

iTrader: (1)

Is the EGT that important? It depends on how picky you are about tuning.
Overall, you seem to have a good handle on the piston type, AFR, and timing. It really comes down to dynamic compression, fuel type, AFR, and timing. If you pull out timing and reduce the dynamic compression to limit rattling then cast or hyper. pistons work fine.
If you want to run high dynamic compression (high boost) along with cheap fuel and a lot of timing then go with forged. It all comes down to how close you want to run the engine to the hairy edge.

Personally, I have a high mileage stock 305ci TPI 9.5:1 compression with a turbo setup that I frequently run 87 octane E10 fuel. I run the ECM off of the WBO2 in closed loop and target a 12.2 AFR at WOT. It also has a water/alky setup that is progressive ECM controlled. I run up to 8-9 PSI of boost in a 5000 lb truck. Why does this work without breaking pistons? I pull timing to reduce detonation and at the same time HP. I do this using the knock sensor and ECM that I did a lot of tuning on. When I put 93 octane E10 in it the HP comes back.

For you application I would run the hyper. pistons in terms of lasting longer and having better blowby and heat characteristics. If it was a race/track rig and needed every bit of HP to win then I would go with the forged units. Just my opinion and opinions will vary.

junkcltr

iTrader: (1)

Here is another to consider:
http://www.jegs.com/p/GM+Performance/752506/10002/-1

chevy1500z71

thanks for all the replys, very helpfull.

heres an update, the 2 bolt motor seems to be out of the question for a few reasons that i wont go into because its not important.

anyways, a guy called me with a 350 motor that was in a stock car, all forged with 6" rods, 4 bolt main, older block and he ran 2 races in it. it has worked stock type heads with a moderate cam (little or no overlap) and low compression. this things got it all. im afraid it may be a bit of an overkill, he was just rambling off all the fancy crap it had left and right, billet this and that, adjustable cam timing, it comes with the intake and carb and all and hes asking 1500$. he said it dynos 280hp with the class rules forcing him to use a 500cfm carb and stock type exhaust manifolds. im going to go take a look at it tomorrow. he has all the papers so i can get some real specs on the cam and such

so my biggest concern as of now is what is involved in putting an early model block in my truck?

so what do you guys think, buying a motor from a race car= no no, or = badass? lol

Apeiron

It might not be what you'd want for a truck.

chevy1500z71

whys that? its nto a real radical cam that would require a high stall converter. it was just a pretty mild circle trac car.

and when it comes down to it, practicality doesn't concern me as much as most. the truck drives around with no swaybar, 35" tires, a full locker, the trans shifts firm enough to chirp the tires shifting. its my daily driver, but that doesnt mean ti needs to be insanely practicall. as long as it gets gas milage in the double digits, im happy. 12mpg is my goal for the new motor, i could live with 10.

scribbles

This seems fishy, Why would he spend that much money on a motor that could be claimed for $500? Or did he claim it and is trying to flip it?

Apeiron

Because everyone else spent that much money on their claimer engine, too.

chevy1500z71

i bought the motor tonight, hes pulling it for me this weekend, i jsut gave a downpayment.

anyways, its not a claimer motor hes flipping. he had the motor built and i have a full folder with all the receipts and everything he has in it. he said he had about 4000$ in it. he only raced it 3 times and he stored it in his buddys shop and the shop cought fire from a brush fire and the car had some fire damage, no insurance or money to fix it and it sat for about a year.

heres some specs on it, the cam will need to be swapped.

heres some specs since i have a whole folder full of em for the motor now.

isky cam-
hydraulic flat tappet
lift: intake-390, exhaust-410
duration: intake-276, exhaust-280
overlap: 66 degrees
lobe center-106

@.50 the duration is 236 intake, 240 exhaust

with 1.5 rockers and it has 1.6 rockers in it.

lunati lightweight forged pistons on 6" rods

roller timing set with billet timing cover with adjustable cam timing.

fluidamper harmonic damper

stock type heads with stainless valves and isky springs w/ 1.6 crane cams rockers.

all arp hardware

racing starter motor

comes with a distributer, don't know much about it.

intake manifold and a 2 barrel carb.

and i think itl include some junky stock type exhaust manifolds as well.

o yea, and of course the block got all the fixins at a machine shop, about 600$ worth there. it was also ... can think of the name, when you measure the top of the piston and deck the block flat to the piston is even at top dead center.

Apeiron

Zero-decked.

What bearing clearances was it built with?

chevy1500z71

there you go! the name was on the tip of my tongue lol

anyway, i do not know the bearing clearences. i can ask him. he said it was a pretty mild motor, he was going to build a jeep with it but he needs the money. it should be reliable.

scribbles

sounds like a great buy. Hope you enjoy it.

I am glad you got forged pistons, i think they are nessary on a blown motor with any real boost.

WASyL

Yes, because You can have optimal AFR but EGT still can go way to high especialy on WOT in higher range of RPM's, for V8 with turbos it is goot to gave at least 2 EGT, one for each side

chevy1500z71

im having a problem finding any good blower cams for the motor, all of the m start at about 2000rpms and i have a 1500rpm stall converter. so am i going to need like a custom grind cam? or can i get a non blower cam in the ballpark? see i have a weird set up. i want a torquey motor with alot of bottom end grunt becasue its a pickup truck and it has a low stall converter. but on the other hand, this motor will have no problems spinning to 6,000rpms and id really like it to run up to there since i can.

scribbles

Have you called comp cams? they are verry helpful.

ibmtech

iTrader: (1)

I went with the Crower EFI Blower Cam. I initially got the 00484lm but had them custom grind another for me for the 4 - 7 swap on firing order which was part 00009. I bought JE forged Pistons 22cc Deep Dish for about $900 and forged H-Rods. My last motor took at dump at 18lb of boost. This one is holding fine and once I get the intercooler on, I am going up 2-4 more lbs. I would always recommend forged internals.

junkcltr

iTrader: (1)

That is what every engine builder wants. Unfortunately, electronic lifter technology is not ready at this time to dynamic alter cam timing. So, you are stuck with a trade-off like every one else. Since it is a truck I would go with with a cam similar to a small duration nitrous grind depending on the heads, exhaust, and intake.
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Not when I called them about a turbo cam. They do have "turbo cam" grinds listed. I had to give him the part numbers because he only found one of them. After giving him the numbers he would say "that would work too". I started talking cam timing and then got silence........it was beyond what the catalog had in it. The just do computer lookups for you. We can all do that these days because of the websites they have.