Lt1 bottom end, how much can they take?
 

Ok, so I'm pricing different options out in my head forming this winters plan of attack on the z if I do wind up tearing it down.
My plan is to finally convert the 2 stage nos cheater kit I have for efi use and run the car on spray.
Now, I'm torn on keeping the lt1 or going ls power, but, since this is the lt1 section let's talk lt1 bottom ends.
I already looked at and priced up a fully forged 383 rotating assembly that I know would be basically bulletproof for whatever I want to throw at it. And yeah, it'd be great to run a 300 shot and go balls out but on this car I don't think I care enough to add all the shit I'd need to track an 800+ horse car.

So, thinking realistically, if for once I can actually do something with moderation (very difficult for me trust me lol) what can the stock lt1 bottom end handle? Say I stay super budget and just do rings/bearing, some good arp fasteners, and call it a day? I'd probably upgrade from my hot cam to something a little bigger but nothing too crazy since I don't think I want to buy heads, and my heads/hot cam combo already put 319 to the wheels on a poopy tune so I'm guessing what's on there flows ok. Basically, how much of a shot can the stock bottom end take and be semi reliable?

Option 2, spend some extra and get at least forged pistons along with everything in option 1. I'm assuming the stock pistons are the biggest weak point. Taking them out of the equation how much more can I add safely? Only thing really stopping me here is the cost/headache of getting it all rebalanced. At that point I may want...

Option 3, a full cast 383 rotating assbly from eagle. About half the money of the forged stuff but is it even as good as stock?

Basically, I'm assuming I'm close to 400 horse at the flywheel now. I'd like to get closer to 450 by freshening it up, going bigger on the cam, and doing some tuning. Then hit it with 75-100 horse on the first stage and then have the second stage put me between 150-200 horse total. Just trying to get some opinions on what I need to be fairly reliable strengthwise.
Already got fuel system, colder plugs, timing retard and all the other associated odds and ends sorted out. Just need to settle in on which hard parts will get me there.
I'm looking for a solid mid to high 12 second car on the motor and mid 11's on spray. I think that'll have me more than satisfied with this project.
So, lt1 guru's, discuss away.

stock lt1 short block record is held by a 3100# 3rd gen bird with ported heads,comp cam 276 n2o grind and a cheater plate with 82 jet..which is either 180 or 210 shot depending on tune..record is 5.99 1/8th and 9.44 1/4 on 275s with rod bolts

So that should give you a idea and i think hes making around 450rwhp on motor..im looking to be making 600hp on motor and then spraying 210 to my stock short block an im going after the record above for kicks..but dont get me wrong my goal is to blow my shit up once i get all the shit to go turbo..lol mine and the other guys cars are race shit though..not someting i would do every day..


On that note though i know more then 1 person that used to spray 150-175 shot to there camed cars all the time.the 2nd stage is what would get you..plus with cast pistons you have to pay super close attion to the tune up


the cast 383 deal well would be no better then running the stock crank with some h beams and some cheaper style forged pistons..only thing you would do is gain the cubes..if i was you i would just do some srp pistons and h beams or get a whole forged kit..


My next step for me if i stay juice longer will be forged pistons and h beams..then swap pistons and ad a forged crank for when i am turbo.

What's the stock crank good for?

And the stock rods are no better than the stock pistons?

I know damn well I've sprayed a 150 shot into a stock cast piston Pontiac 400 for plenty of time with no issues. But that motor also probably only made 350-375 horse off the bottle if it was lucky.

I don't mind leaning on it a bit but I don't want to build a total grenade, nor do I have any intentions of going after any records.

Just don't want to spend any more than I need to on this car to hit my goals. This is not my balls out no expense spared project. Just my budget beater to toy with while I work on the full on project. The z is the one I'll drive with extreme prejudice cause I really don't care about it lol.

Hell, I've seen deep 11's on heads, cam, intake with a stock short block. So, at what power level do they come apart, regardless of if they are na, or have a power adder. Assuming of course the tune is on.

Noone knows they don't run long enough to find out

i aint heard anyone breaking a stock crank..but to let you know i will be around 800 and im not thinking twice about doing it...i also had a 327 with stock crank,stock rods with rod bolts and trw pistons and it made around 750..lol im lil diff..gm stock shit can take a hell of a beating

the rods i think are the weak point but once you do rod bolts the pistons are next in line....arp rod bolt kit for stock rods is 70$..or you could go to speedway motors and pick up a set of there forged h beam rods with arp 7/16th bolts for 250$.

Then float around and toss a cheap forged piston on the rods and bolt it all up..

like i said crank is the last thing i would sweat on the rotating assembly..rod bolts first,pistons then rods then crank.shit you might have to address the caps on the block before the crank....but make sure you get your crank checked an stuff..if you beat on her like you say.as you know its always best to mag it and make sure and turn it down if need be.

Yeah, after doing a lot more research on it I think if I do wind up tearing into it I'm gonna do just like you mentioned, a cheap set of forged rods and pistons on the stock crank and call it a day. Up the cam a little and whack it with a 200 shot. All I'm looking for is mid 11's on the bottle and I'm fairly certain that will get me there lol.
On another note, small block chevy rods and pistons are universal not lt1 specific correct? Just get whatever, have it balanced, and I should be good to go?

as long as you have the crank rebalanced for the new rotating weight any SBC gen 1/2 rods will work. as long as your obvious things are met like piston is made for 5.7" rod yada yada

And ditto on the pistons I assume as long as the pin fits and it's the right size for the hole? Nothing funky with the valve pockets or anything?

that all depends on your heads and cam setup

i ran with HUGE valve relief so i never needed to worry about PTV. But if i ran a Much bigger cam id be in trouble. it ALL depends on top end for ptv. if your gunna spray id say stay in the high compression ratio mostly stock if not stock heads and a mild cam. and you'll be alright.

SRP makes a GREAT set of entry level/cheaper pistons with a good relief and setup for 355 with a 5.7 or 6.0 rod depending on what you want to go with. id say longer rods would be better to keep the R/S angle a little better for a Hit of nitrous.

Yeah, I'm most likely just going to keep my ported stock heads. I figure with 319 at the wheels I'm close to 400 at the flywheel. Knowing the tune was a bit lean I'm hoping to freshen the motor up, change the cam, clean up the tune, and I'm shooting for 425-450 at the flywheel. I'm thinking that's a reasonable goal.
Then I'll probably hit the first stage for 75-100 and have the second stage come on for a total of 175-200 all together. If I go through all of this my target is mid 11's and I'm fairly confident that will get me there.

Just for super budget I was looking at those rods from speedway that suicidal mentioned. But, they were only a 5.7" rod.
And here's the biggest loaded question of all I'd love some input on, any cam recommendations :D

^they make them in 6" also
http://www.speedwaymotors.com/Speedw...Rods,1790.html

As for everything else i like 6" rods myself but its all up to you..you know your crank,figure out what comp height you want on your pistons an then where you want them for how far you want them in the deck and then figure out what rod fits..me i like pistons with 1.18-1.26 comp height..they can take a load of spray no problem..an it puts the pin not in the oil ring and not way down either an still have plenty of meat up top..but to each there own.

Are you stick if your auto your already around 425hp at the fly wheel an if stick your around 390..remember these trans,rears and drive shafts aint like racing shit..your losing more then you think i've always gone with 100-150 for loss wise on stock cars


What is your weight? stall? gear? shock set up? all that..remember the lt1 bolt on record is held by tom and he only put down 309 rwhp and was 3100 for weight on his 11.48 pass.Yes he was creative and used alot of super stock tricks like engine oil in the rear gear,light brakes an made sure they didnt drag at all an so on.

oh as for cam..your stock ecu also right so you are limited to like 6800rpms or some b.s right..whats the flow data on the heads..where does the heads peak and where do they start to stall,what comp are you looking for..what size valves are in them and what bore are you going with?

Ok, car is a t56 so yeah, about 390 is the same thing I was figuring.

Head flow data I have no idea. They were on the car when I got it. Was told thy were ported but no clue by who or how well so I'm going to assume "slightly better" than stock to be safe. Don't think it's worth my effort at this level to have them flowed.
Yes stock ecu which iirc is limited to 7,000 rpm. Car is stock weight, no lightening done nor will there be beyond probably removing the ac. Was goog to put it all back in but the more I think about it the more I say fuck it lol. It's also got a small system in it so that easily offsets the weight I may lose from the ac.
Rear gear is 3.42 and will most likely stay that way for a while. As for compression that's wide open if I'm changing pistons. All I care about is staying on pump gas.
Car is primarily a street at and will spend 90-95% of it's time on the street. I just want to get the most I can out of a basic combo. Car has stock suspension and if I do make any changes they'll most likely be handling oriented, not drag oriented so I know I'll need the extra power to make up for a dismal launch lol.
So yeah, full weight, so so gears, pump gas, and probably shoo to peak in the low to mid 6k rpm range since like it or not I'm all done by 7k ;)

Anything else, ask away.

nope bout enough..

figure since you want to stay on pump gas and aint looking for something radical an not sure about your heads..im figuring you will be around 11.5-1 max for comp..heads probley are dead by .550 lift so i would say i would do lift around .580 max so you dwell in your peak area a tad longer..you have headers?roller rockers? all the main supporting bolt on mods i take it right..if so i would probley say try the comp cam n2o cam..the nx276 with a 1.7 rocker which is .589/.568..224/236 dur@50 an a 113 lobe.with 1.5's its .520/.502

Its actual the cam i was org going to go with for my car before i got a deal on my herbert roller i have for sale..my deal with stock cleaned up heads was going to be that cam org,1.7 rockers,11.4-1 comp using a .015 shim gasket,200 shot and shifting i was figuring around 6800,750 carb and my holley strip dom intake.

if you go that way you probley have to get the cam custom done so it can work with the opti but im not sure..just call comp..if you want a custom grind

bullet,cam motion and comp will make you a killer cam for sure.

Ok, now this has my wheels turning. I know the stock block has seen well over 800 horse, at what point does the crank become the weak link?
Now I'm considering gig through the lt1 I picked up for my 87 bird, adding forged rods, dropping the compression to say 8-8.5:1, and strapping on a turbo. Hit it with say 10-12 lbs of boost on pump gas with meth injection and call it a day. At that point I'd probably be making 550-600 horse if I had to guess. Yeah it's roughly the same number I'd be making on the second stage with the nitrous combo but it'd be making it a lot more often. Hmmm...
Maybe even crank it up to 18-20 psi? Something tells me after I clear the 700 horse mark I'm asking for it. Or is the stock crank up to it?

For the extra few bucks I'd sit down and get a custom grind cam from a pro. I agree with suicidal that that is in the ballpark of what I would say but it is probably cheaper to get a custom ground then invest in 1.6/1.7 rockers (although I have had very good luck with the GM 1.6's and they don't break the bank). Biggest thing with the cam is to have that extra exhaust duration to get that pressure out of the cylinder bores as fast as possible. As for the boost I'd seriously consider a forged crank if you want to do that and 20 PSI you may blow the block

No I don't think I'd go 20 psi, but I have heard of the stock block surviving over 800 horse in more than a few applications.
Realistically I probably wouldn't go any more than 14, probably more like 10-12. It's more the crank I'm worried about.

well boost is less stress on the crank then n2o..from all the shit ive seen people do and such rule of thumb i go by is 100hp..so you can do 800hp on juice and then 900 on boost..boost is less violant on the parts.it dont shock the parts as bad.


No for power wise a bw s400 75mm turbo would make for a nice piece..with race cover there good for 950-1000hp maxed out.So you figure with 10-14 your in the solid 500-600hp range..At this point i would def just have a cam speced out for me..Its nicer to have one speced for your app..You could get a cam that might want to spin to 7200k even though it says the rpm range is peak of 6500rpms.


As for stock crank ive not heard anyone break one yet..but im new to the lt1 world but have looked threw alot of post and know they can take some shit..i think around 800-1000 hp the crank flex is really the killer at that level an its just better to ditch it and be able to turn her up if you want to with out thinking i have a bomb on my hands maybe.

your 355ci or so right,i would go with a 2.5 cross overs for the hot side,you can use the 3rd gen ebay turbo headers and mod them some to work..headers are 190$..they are not the shorty twin turbo ones but the long ones. cut the ends off an to your hot side out of a cheap tail pipe exh kit..then send the headers an hot side for coating.

You can get a kit with a 75 s400mm turbo with waste gate and blow off for around 1100$..so now your about 1800$ into the hot side,cold,headers and turbo.intercooler is up to you.you can just run meth injection..which -20 windshield washer fluid is cheap.

Yeah, as far as fabbing up a turbo system I'm no stranger to that. Been there done that and yup, the bw turbo is exactly the same thing I was thinking.

I guess the whole question I have now is at what point does the stock crank, or 2 bolt main block, fail?

never know.think a block that was beat on all its life vs one that was just run normal are going to give 2 diff out puts to that question.

im looking to be 800hp with mine on stock 2 bolt and crank..i might strap the caps on it if i can find some one with a mill.