you're gonna have to run a lot of race gas with that sort of compression. good luck with everything! ill be going with a 355 myself, but i plan on keeping compression below 11

 

i have personally ran 12.2:1 on pump gas on the motor, and it runs fine... but that is about the max compression that you can run on 93. It can work if tuned correctly. a scat 9000 basically is a stock replacement.

i find it hard to believe that for the same price and reliability someone would go with a smaller engine

now i see, having to defend your position.

because a bigger engine wont work with an aggressive cam? im confused, every engine ive built, for a given driveability the bigger engine uses a more aggressive (i hate the word 'big' when it comes to describing cams.) cam and makes more power. and if youll read below, you can actually use the same cam and not only gain power, but run better at the track where it counts.

you are right, it feels more driveable. i had a buddy with an LT1 in 1996-1999 that we worked on together. after the stock shortblock wore out we put together a 12.2:1 396 for it. he didnt want to spend money so we just put the same heads/cam and everything back in the car. before, on the stock shortblock its best pass was a 12.20@117. that was with 402rwhp.

after the 396 the car made 437rwhp and ran a best of an 11.30@123. this was with the same heads and cam. 35 peak rwhp and 6mph. performance isnt about peak hp. with the 396 it peaked at 5900 instead of the 6400 it peaked on the motor with the 350. but after peak the 396 still pulled to 6400. i managed to talk him into putting a bottle on the 396 before he totalled the car in a street race and it made 655rwhp. that was with a NOS dry kit jetted for 175hp. the car went a mid 10@134 like that. on the bottle we spun the 396 to 7000rpm on the dynojet, which was where the peak power was. at the track he short shifted it at 6700 because he didnt want to break it. there is something to be said about making your own atmosphere.

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i def agree about the whole bigger cubes thing.. but i honestly dont have much money tied up in the rotating assembly for the 355 probably less than 600 bucks.. i do plan on building a 400+ci motor in the future but just opted to go with the 355 for now.. 1 for money and 2 just for the fact that no one can use the "you have a stroker" excuse..lol.. and edwright also claims he can tune if for 93 octane.. i will probably just use the same 114 out of the n20 fuel system and mix it half and half with 93 for the main tank.. i can get a pretty good deal on a 55 gallon drum of 114..

 

where is a 383 the same price? typically, when someone decided to go with a 383, they dont reuse their stock crank or even get a stock replacement, they drop another ~$400 on a Scat crank. For the money, you can put more into your .030 bore by staying with smaller displacement.

I have no problems with 383's. They do prove to be the best choice if you want to put up big numbers and good track times. Im simply stating another alternative to going with a 383 and saving a couple hundred dollars. The answer to every rebuild can't be a 383...

There are many people putting up great numbers with both 355's and 383's. My statements are just offering something different than the 'all-mighty 383'...

 

383's hav diff strokes, you can't use a stock crank or stock replacement. I wish i had gone 383. I didn't because they seem to only make a few more horses over a 355. Where they really shine is torque, and area under the curve.

 

not everyone feels that their particular car needs to lay down great numbers at the track. im one. track times are nice to gauge what you've done, but my life doesnt depend on what times i get at the track. im more interested in drivability, mid-high RPM pull (street/highway driving), power/pull off a roll, gas mileage, sound, etc.

 

yes they do have great torque over a smaller displacement engine, but since im not out for gobs of extra torque or the best track times, a simple 355 rebuild with lightweight hypereutectic pistons is a great option for me. im simply letting this guy know that a 383 isnt his only option, as many people on this board would like to believe...

 

my first car was a bbc chevelle.. i have felt all the torque i need.. my buddy got an lt1 car and i just couldnt get over the top end pull... we would race.. i would auto matically jump about 4-5 cars on him then he would reel me in and fly past.. that has just recently caused me to get an fbody and try out the ol mighty 355 thats also the reason i went with the cam i did.. i want some reel races..lol.. the 400+ motor will probaly be s/c.. just testing the waters here.. im not out too much money..

but back to the subject.. lol.. think it should run alright.. and besides the ci factor what would you change..lol..

 

that was my point.

there's no way a 355 rebuild could cost the same as a 383 rebuild, everything being constant. An aftermarket crank already sets someone back ~$400...

 

They aren't that expensive. Thats what i thought originally. Jegs has them for $200-300 for a cast crank. Not all that much in the grand scheme of things. I just wish i had the torque of a 383. Torque is what is so damn fun to have.

 

do you know what sort of numbers youre putting down with your 355? im thinking youd be at 380rwhp+ with the mods in your sig.

 

he bought a scat 9000 crank, its the same price for 3.48" stroke in a scat 9000 as it is for a 3.75". same with the rods and pistons. thats the point.

 

yes the different strokes cost the same, but if he were simply getting a stock replacement cast crank hed still be saving money over a 383.

 

how does that figure into this scenario? i was wondering why he went with the shorter stroke in the scat 9000 and he answered me.

he is wanting to run nitrous on top of a 400rwhp h/c combo. who would be stupid enough to run a stock crank? thats building a bomb. for a reliable combo he is needing an aftermarket crank, and in that case its the same price for the different strokes. that is the point. why are you even bring up stock cranks? if you want to run a stock crank on a heads/cam/nitrous motor because you can save a few bucks, then have to rebuild it ever time the rotating assembly breaks then good for you. there are some of us that want to do it right the first time.

 

Damn dude. For you to keep arguing about this in favor of less power for the same money is pushing the limits of credibility. The ONLY reason that I can see to build a 355 instead of a 383 (in todays market) would be if you there was some kind of class rule that limited you to stock displacement (or a 30 over motor). The idea of a 350 being able to out rev a 383 (by any large margin) is pretty much bogus. Yes, piston velocities increase with a 383, as does airflow, and mechanical advantage of the stroke increase, but it's not enough with the parts we typically by to see any kind of difference in RPM capability. I push mine to what the stock computer will allow almost every day (7000), and it gets to it in a serious hurry.

The bottom line is, that if your going to compare the cost of building a 383 to the cost a 355 dollar for dollar with the same type parts (yes, you can get a 3.75 stroke CAST crank from any number of places for low $$ - always have been able to), then the ONLY increase in dollars spent is the clearencing for the rods on the block. And that doesn't cost much. Everything else is equal. Everything.




Now as to the original post....

Can you post up all the specs on this stuff so you (or actually WE the motor voyers ) can figure up your dynamic compression? Cause 12.2 static isn't a big deal with the right cam. It's harder to tune for, but not the end of the world. I have 12.45 (give or take a little for my chamber work), and it runs like a champ on pump gas. I'm in need of a good dyno tune, but it's not THAT bad to run on pump gas. And when you go to the track and get some good gas, it's a LOT of fun to have the higher compression. High compression motors just sound a little more pissed off through open headers than the other cars Daddy like

Good luck man.. Hope it turns out good for ya..

Dave C.