Lt1 bottom end, how much can they take?

[bottledbird68]

Originally Posted by ILuvPizzaTimes10

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

[Suicidal racing]

^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.

[Suicidal racing]

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?

[bottledbird68]

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.

[Suicidal racing]

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.

[bottledbird68]

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?

[Batman]

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

[bottledbird68]

Originally Posted by Batman

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.

[Suicidal racing]

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.

[bottledbird68]

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?