383 or 355?

[jseal-57]

with my setup what should i go with a 383 or 355?
i got LE2 heads flow 275/190cfm
cam is 228/236/592 lift 112lsa
and i have the port matched intake for it as well.
the car is a 6speed also. and what would be your guess for with a nice street motor?
im looking to get 380-400 whp then run nitrous. i believe the heads are a 52cc
if you could let me know what pistons and stuff to use that would be a big help to
im going all forged internals h beam rods. thickness of gasket would be good to. i think i want 11:1 or 11.5:1 compression.

[96LT1355Z28]

Both dispalcements will get you the HP level you want, I suggest loking for an ET rather than HP. From my experience the 383 will make more TQ at a lower rpm than the 355 but both are capable of the same power levels. You'll just have to spin the 355 a little higher.

A pretty standard setup would be a set of forged -5cc pistons, a 6" rod, and a head gasket of your choice. Your gonna need to know what deck height your block is gonna end up at to figure final comprression ratio. With the choices available 11.5 to 12.0 are easily doable, again depending on you deck height and gasket thickness. There's several calculators out there you can play with to figure deck height and gasket thickness for comptession ratio. We have one on our site on the useful links page.

You'll want to discuss ring choices with your engine builder if you plan on using NO2. They can also go over your budget and the machine costs involved with 355 vs. 383 to help you decide which is best for your goals.


Just a friendly reminder from someone who's been there, make sure your car is built for the engine before you build the engine for the car.

[1sickta]

The cost of the crank & clearing for the longer stroke is going to be the price difference if your going with new pistons and rods anyway. The cam is going to determine the actual C/R. With the right tuner you can run 12:5/1 on pump gas and N20. Quench is very important when running a high C/R. .040" is a ideal quench. Lots of people like to be in the .05X" just to have a little more PTV clearance.

[jseal-57]

i just finished installing new moser 12 bolt and going to build my t56 with the viper spec rebuild kit. and get a new driveshaft. i dont want to spin the engine that high maybe 6500. my main question are my heads and cam big enough for a 383 or are they a bit lacking? im getting a shop to build me a short block then im going to put everything else together my self. whats the differance between the 5.7" rods and 6.0" rods (pros and cons?). that is the piston i was thinking was a -5cc. what else should i look at replacing on the car for the motor upgrade. I just put in new 255 fuel pump with hot wire kit and if i go with a bigger shot of nitrous then a 75-100 then its getting its own fuel system. would the 383 be a better street motor then the 355 for the same power. what do i need to get the car running 11.5-8 1/4 mile on just the motor. it has 4.10 in it and is pretty much full weight but going to take out the back seat and a bunch of bolt on stuff and spare tire. the car also has M/T drag radials 275 50 15.

[tt383lt1]

i would do a 383. and you will still have enough cylinder wall thickness to run alot more than a 100 shot. if you have the funds i would do a 383 with splayed 4 bolts caps.

[MeanTA]

A 6 inch rod will give you less side load on cylinder walls. But with a 3.750 stroke it will push the pin into the rings. So i would suggest a 5.7 rod a 5.85 rod if you can find some pistons for it.

On a street car and a 6,500 rpm goal. I would say 383 because it will give you more low end torque. And bring your peak power goals in sooner.

Your heads will flow fine for a 383. My heads flow the same numbers as you. And Im making the power in my Sig. And its making 400 ft lbs of torque at 3500 rpm. From a dig i shred my tires without even trying:)

For the rest of the car just make sure you upgrade the suspension(control arm, sfc, trans crossmember ect) our stock suspension was not built for these power levels. And will show it at 400whp.

I follow the moto.... Broken engine will ruin your day. Broken suspension will kill you.

[jseal-57]

A 6 inch rod will give you less side load on cylinder walls. But with a 3.750 stroke it will push the pin into the rings. So i would suggest a 5.7 rod a 5.85 rod if you can find some pistons for it.

On a street car and a 6,500 rpm goal. I would say 383 because it will give you more low end torque. And bring your peak power goals in sooner.

Your heads will flow fine for a 383. My heads flow the same numbers as you. And Im making the power in my Sig. And its making 400 ft lbs of torque at 3500 rpm. From a dig i shred my tires without even trying:)

For the rest of the car just make sure you upgrade the suspension(control arm, sfc, trans crossmember ect) our stock suspension was not built for these power levels. And will show it at 400whp.

I follow the moto.... Broken engine will ruin your day. Broken suspension will kill you.

when i did the rear end i upgraded everything to umi and qa1. and when i pull the motor the front is getting the k member kit with a arms and qa1 as well.

[383z]

It looks like your good to go...for a 383 ;)

[jseal-57]

would it be worth it to go with the 24x conversion when i do the motor. im not going to be spining it to the moon or anything. just around 6500 and i still want it to be easy to use with my nitrous.

[BLK95-Z]

no replacement for displacement :)

[Soxxpuppet]

That question has been coming up in my mind aswell. I recently purchased a 4-bolt block out of a vette. After alot of thinking on the matter I decided to run a 383. Comparatively they would cost almost the same but the 383 would make tons more power and any rpm. As for the 24x, im sure you could get away without it for right now. But it would make life easier later on with tuning capabilities.