My buddy is wanting to rebuild his 350 lt1 he wants to use forged 6'' rods and pistons. with the stock compression what pistons are his best bet?
Any help is greatly appreciated.
These are the rods he currently has what pistons will work best with these?
Eagle Specialty Products 6000BBLW - Eagle SIR I-Beam Connecting Rods - Overview - SummitRacing.com

 

While the above post is maybe "technically correct" it is also wildly overcomplicated. Many of the details we can "assume" or fill in ourselves.

What I would ask is, is he looking for a performance build? Is he addressing the heads and cam? Why does he want stock compression?

Far as choosing a piston based on exactly what you wrote he would simply need a flat top with generous reliefs 5cc or so leave the deck of the block and heads alone and get a stock mile thick head gasket. I would never do such a thing but it is what you are asking for.

If stuck on low stock compression but wanting to do it a little closer to "right" then he could consider decking the block/heads, using a thinner head gasket and a 16cc dish, at least there would be some quench then.

Really though for a performance NA build compression needs to come up, even a stock LT4 was higher compression, most guys raise compression at least a full point and a lot even approach 2 full points more compression with pumpgas street LT1s

 

Well first off, if he still has the box and receipt, he should send those junk rods back and get the Scat Pro I beam for only $50 more.

As for pistons, a Mahle -16cc powerpack set with a thinner gasket would be pretty close to stock compression and yet get better quench. If running a bigger cam, it's easy to bump the compression up with a regular flat top piston and still be safe.

 

Thats one thing I learned about the internet and forums....you can never assume
I agree with what everyone is saying. Need to know alot more details before picking a piston.

 

I used scat procomp 6" rods with 7/16" rod bolts.

 

Thanks guys for the info. Its an automatic car. Hes on a budget. The motor had weak oil pressure from him beating the crap out of it 100k. He wants to at least do forged pistons and rods use the stock crank. Maybe have the heads cleaned up a little bit and have the intake matched. He said hes going to go with whatever cam the builder chooses which is stupid if you ask me. I told him if your just going to have a cam put in thats street able and easy to tune go with the lt4 hotcam kit. Its mostly going to be for street use.

 

So he wants nothing to do with an intelligent well thought out plan, he is just going to march blindly forward with what he has decided?

If on a budget he could save a LOT and do things as least as well as he plans.

 

I dont see a problem with it. Even on stock heads, a good cam swap will give 340-350whp. Stout little street motor. If heads are mildly cleaned up, bowl blend/valvejob....they may make 360-375whp, possibly more if more port work was done.

Nothing wrong with a stock crank build either...I've seen them turned to 6500 rpm alot and live just fine. With good rods/rod bolts it should live. You can make plenty of power under 6500 rpm. Could get away with cheap I beam rods and hyper pistons too if not spraying...

For budget, I'd find a used c503 cam. Abit better than hotcam and available for cheap on forums.

 

I find it laughable that everyone thinks power is so easy to come by with nothing but mediocre parts. Just this week a guy made 36x rwhp with "top level" larger valve ported heads and you are telling this guy he can do better than that with almost nothing for performance work.

If it doesn't need pistons I would not buy pistons. Since he is "on a budget" he would probably have the shop buy some antique crap that isn't even as good as stock.

Either pocket the savings or put it into something that will make power. Far as the crank, it is reliable beyond the pcm's capabilities guys take completely untouched shortblocks past 6500rpm every day and guys who put in fresh bearings and resize the rods take the stock shortblock to 7000rpm every pass without issue.

 

I'd bet my salary on it. seen it over and over and over again man. Sorry you spend 1000's to get where you are at. Not everyone has the same results as you. Some can go faster for less....


360whp is NOT that much....... I've done that + 40 on shelf parts. My old buddy's 95 z28 full weight car with CC306 cam only makes 340'swhp thru an auto. Hell an old low compression sbc made 330whp that I tuned with mediocre heads and 280xfi cam and it made that by 5700 before going into valvefloat. Knew the springs werent gonna be enough but its what he had. Would have peaked low mid 6000s and made 350-360whp easily. Slapped together combo, stock shortblock

Dont get caught up in dyno numbers. I know cars that dyno 80 hp different on 2 different dynos. One mustang dyno vs one local dynojet. Car on the SAME day dyno'd on the mustang and put down low numbers. Owner didnt like it so we took it to another shop with a dynojet, put down 80hp more.... Car runs the same, no difference, just different "numbers"

Also, whos to say that his 36x combo wasnt a mismatch, or wasnt assembled right or wasnt tuned right? Just because you have top dollar parts doesnt mean you will have a top dollar engine!

You act like you HAVE to go to AI to get a combination that works...i find that laughable.

And I agree, if he doesnt need pistons, then dont get them. But if you need pistons for a rebore on a fresh rebuild motor (makes sense to do a bore/hone at this level) then you can get away with cheaper hyper pistons than forged if you dont turn alot of rpm or spray or boost.

 

I said nothing about what parts I use and do not think what I am using is appropriate for this "build".
No need to try and dismiss my opinions by trying to pretend I am being unreasonable and pushing only what I use.

What I am saying is it is a waste to go blindly boring the block for forged pistons and such and not do something good about the topend. The stock parts will handle a LOT more than he is looking for.

Far as what I have spent for what my car runs, it is a 4200lbs grandpa car with the top[end being the only thing I have spent a "lot" on. By all but YOUR accounts it runs very well for what it is.

Heck I would question how you make something so slow with twins pushing 14psi under the hood. Friend's street Chevelle went 9.7 sunday NA with a 402, must be that one extra cubic inch.

 

It certainly sounds like your pushing a different agenda... Maybe I'm reading into it but you make it sound like doing mild things to heads and using shelf cams cant make power on a budget when 1000's of posts here prove that wrong over the years. Its well proven that most cam swap stock heads cars make between 330-360whp. Thats a good little budget setup.

Now I agree, maybe blindly boring block for forgings is alittle misguided but we dont know his plans. Maybe he wants a built bottom end for the future or plans to spray someday? Hard to say what he wants to do. Maybe its for piece of mind in having strong parts. Nothing wrong with that, if thats what you want to do with your money.

I'm not saying your car runs poorly.... It runs well but you have top dollar products on the top end and from that, you saying "I find it laughable that everyone thinks power is so easy to come by with nothing but mediocre parts." when clearly it is possible, it makes it sound like you want to push top dollar stuff.

So dont take shots at my car when you know nothing about its build history or purpose. Built using left over parts from a 383 street motor and built as a base for a future build..which is going on now. Before it was 3600 lbs with pump gas only street driven everywhere car with small heads/small cam, 2.73 gears for highway cruise and leaving off motor only at the track, no boosted launches...1.6-1.7 60 fts. 141 mph traps is NOT slow for a mild combo. I bet your friends chevelle is gutted race car that cant sip pump gas and doesnt trap 140's and has a 60 ft better than 1.6 And mine has gone 9.72 at 142 as well... quiet as a whisper too

Believe me, if I wanted a 9 second n/a car, i could easily build one. My new heads alone could support it...8's with boost driven to the track on pump gas just sounds better

 

I ran a 355 with a forged crank, forged pistons, and forged 6 inch rods. Stock heads and intake and made 380 RWHP. Now granite I had all the boltons, true duals and a few other tricks. I was a 6 speed that made it a higher number than an auto but still. Just make sure you get rods with good bolts or studs. Yea my car was a freak with numbers for stock heads but thats what it made. 2 diff dynos.

 

This statement is either you being disingenuous, or just simply ignorant. A polish on a crank costs $50, a grind and polish is $150... Youre not saving money by purchasing a $200 cast stroker crank that then needs a $300 balance job.

 

Now you're just talking out of your rearward orifice, and obviously have no clue of what you are speaking. Ignorant means that you are ill informed about something, that is in fact what you are in regards to this subject, it is not an insult, but a statement of fact.

We do $50-$100 jobs all day long, no good shop does work that's not needed or asked for just to drive the price up, and shops don't just swap parts out without prior notice unless they want a visit from the BAR. Are you a professional in the industry, what position are you in to tell me how much money needs to be made on each job to pay the bills?

Grinding flywheels - $40
Magnafluxing heads - $50
Surfacing a head - $75

Hint: Keeping the lights on is about profit margin on jobs based upon time to complete vs. price charged, not just an arbitrary number plucked from the sky.

I can tell you from professional experience that those Scat cranks are not even close to balanced out of the box, in fact I have two of them at the shop right now with LT1 bob-weights that are either getting two slugs of mallory and a 350 damper, or a 400 damper with a large drill hole...they would shake if installed without correction.