quik95lt1

iTrader: (7)

If your goin boosted I would say the more cubes the better, I would absolutly build the 383, even if the heads are a bit shy of what they should be. With boost the heads don't matter as much as they do with a NA motor. Think about 15 psi of boost in a 4.000"X3.48" Cylinder, now think about 15psi of boost in a 4.040"X3.75" Cylinder and both of those cylinders are being compressed to the same amount. You can fit much more air in the 383 obveously, however under a boost condition its not just an extra 30 cubes of air, it's multiplied because of pressurized air vs. outside air pressure (in a perfect application ie. 100% VE). Thats why the little four cylinder pea shooters can handle like 30lbs with no problem, becuase they're jamming 30psi into a tiny area on a small piston head, we are jamming 15 psi into a massive area with a large piston head surface area. Its basic math!!! For NA motors more cubes + good air flow = more power...........for boosted motors more cubes + Boost = much more power!!!!!

22lambo

iTrader: (1)

Nice! Looks like I'm building a 383

AChotrod

iTrader: (17)

you can go just as fast in a 355 w stock crank na!

93Z2871805

iTrader: (5)

There's no replacement for displacement. And with boost your volumetric efficiency will be over 100%, actually closer to 115-120%. My pops 408 BBC sees 96% at 4500 rpm NA, but that's because of the big block heads on a fairly small displacement motor. If he used the same heads/cam on a 496 his volumetric efficiency would probably hit 87% at best.

kinglt-1

iTrader: (26)

hes not goin na lol! And it depends on what parts are used. Yes I will agree in most builds a 355 will be plenty, but saying a stock crank 355 will go just is fast is a blanket statement! your m6 350 setup trapped 119. Larrys a4 396 trapped 126. Please enlighten me on your theory!

AChotrod

iTrader: (17)

Larrys has alot more done to it and a bigger cam. The car is why more set up than mine and leaves with a 1.4 60ft. Im not sayin a 355 is faster Im just saying you can go low 10s @ 130 Na on a 355, add a blower to that and you could go faster than 90% of 383+ cars
Look at Gizmos 355(stock heads intake and TB) vs Larrys 396 since we are compairing apples to oranges

myltwon

iTrader: (1)

more cubes aren't a bad thing, no reason a larger motor can't do everything an equally setup smaller cube motor can but with more torque, less rpm, more street manners, less convertor/gear.

not to say a 3.48" stroke motor is bad, they can do AMAZING things as many have proven time and time again. but in the end like with everything in cars it's all about what you want out of it and how much/what you are willing to put in it.

kinglt-1

iTrader: (26)

Your post above said "a stock crank 355 will be just as fast na". now your saying that it's not lol. I understand your point, a well built 355 will haul ***! You have an awsome setup, not tryin to knock it at all. Im sure your setup is faster than my 383 was. My whole thing is, someone thats new reads your post, then they go off runnin thier mouth that a 383+ is a waste of time because a 355 will keep up! See where Im getting at...

AChotrod

iTrader: (17)

Im not talking about my car,
Did you see the car in my other thread? Stock crank 355 that runs 10.30s at 131 NA.
and its deffintily not a waste to do a 383+ but unless the kid plans on running crazy fast. Its not nessecary. You Need a serious top end to feed such a big engine and thats alot of the extra cost also to make a bad *** 383.
I like both small and big LTxs but i see guys goin just as fast if not faster with a 355s.

quik95lt1

iTrader: (7)

My experience.....I had a stock crank and rod 355 with 11.2:1, TFS untouched out of the box heads, and a big AI hydraulic roller. The car was set up perfectly and weighed 3500lbs with me in it. I would turn consistent 11.40-11.45's at 120-122 with the car. Now my new 385 has only 9 passes on it and with two burnt plug wires and a bad head gasket (#2 compression bleeding into the coolant system) I ran a 10.80 @128 babying it out of the hole (1.68 60'). If you get a combo right and do your homework, yes a 355 will rip. However if you do your home work on a 383 and build it right you can achieve some really serious numbers/times. Its all about matching your cam/heads/CR/c.i....on and on and on to the rest of the car. But again this is one of the cases where bigger is better.

AChotrod

iTrader: (17)

I totally agree^ about it all being in the matching parts to the motor, if they are matched correctly bigger is better, sad part is most with big motors dont do that.

kinglt-1

iTrader: (26)

I agree ac, but your post before made it sound like a 383 was pointless by saying " a stock crank 355 will keep up na". The problem is most 383+ engines are not maximized. most throw the same parts on a 383 that work on a 355, the only gain is tq at that point.

Op check this link out. This one of the baddest procharged 383 lt1's I have seen. These are two local 10 sec street cars on 17's doin battle! That ls1 he is racin went 10.30 @ 137 on 17" dr's!!!

http://videos.streetfire.net/video/B...28s_187925.htm

search call911 on streetfire and you can see more of his vids.

AChotrod

iTrader: (17)

I know who call911 is hes on LTxtech with me

kinglt-1

iTrader: (26)

If figured you did. I posted the link for the original poster, hince op. Since he is building a boost motor, call911 setup is a great reference on what parts work.

myltwon

iTrader: (1)

you also have to remember though that sometimes a bigger motor isn't just for max effort but also more cubes will, like I previously said, increase streetability as more cubes tend to "eat cams" like better operating range, less required rpm, better street manners, etc and the complementing parts (valvetrain, stall, gear, etc) need not be as radical/aggreesive to acheive a similar goal. valvetrain stability and ability along with balancing, though always important no matter what the cubic inch, will always be a greater concern with the more required rpm forced upon it. basically the higher you spin it the more weak links that will be exposed and stress will be forced upon them.

so a larger motor can be dual purpose in reality such as a tamer street machine or a more "max effort" build to squeeze out all available power.

ADM

I wanted to go 355, but I could not justify the cost of the machining and all the parts for it just for 5 cubic inches. Thats why I stuck to 350.

myltwon

iTrader: (1)

well the main point of a 355 is a clean up bore, and larger selection of aftermarket pistons. last I checked aftermarket for 4.030" bore stock stroke pistons greatly outweighed that of 4.000" bore pistons as far as upgrades go. along with the increased cylinder volume of course.

did you upgrade the pistons while you were doing your build or did you reuse stockers?

djjab57

iTrader: (17)

355 Guys are kooler.....................

ADM

I didn't take the engine apart, just the heads were removed during the cam swap.

I did originally want to go 355 forged to spray but I changed my mind.

I am saving up for my next engine hoping to have something rather special. Like I mentioned in other threads before, I have my mind set on that Dart 427 LTx motor if it ever goes into production.

myltwon

iTrader: (1)

ahhhhh I thought you were deciding during a rebuild, nevermind then