i have been looking at alot of post regaurding 388s and 355. and have noticed that the 383s arent doing much better that a built 355.

i know a couple of people on stock bottom end with a small cam from loyd and his heads runing 11.76 NA, and i just looked a thread wiht some one runing 11.9x with heads and cam on a 383 and pretty much the same mods as the guy ruuning 11.76 on a stock bottom end. except alot bigger cam.

so my question is. are the stock ported heads still to restrictve for a 383, (i know there not best)

my goal is mid high 11s on a forged bottom end and spray in the 10s. but is it worth doing a 388 or should i just do a 355.

just wanted some opinions from people runing either of the two.

note: i am going to use the search feature, but just wanted some current opions not last years.

 

I'm not an expert on this but there are 2 differences that i've heard of between these motors besides size obviously. A 355 revs up quicker than a 383 but gives up low end torque for high end power. So 355 is a peakier sounding motor from what i've heard like 6,500+ with big cam versus lower 6k rpm with 383. Personally when i build my motor in a year or two im gonna go with 355 because of cost and I've seen 420rwhp on the Advances Induction site for a head and cammed 355. Either/or is sweet. But in my opinion I think you could make a forged 355 for cheaper and thats where I see the 355 with the upper hand. But im no expert. good luck with the project.

 

Im going with a 383 because i want to do the bottom end right once and i can always upgrade to a larger cam or better flowing heads down the road and make it scream more. im looking to only get around 400 rwhp out of it and i know there is much more to be had.

 

But I can run 11.9s in a full weight stock suspension car.

We built a 355 and its in my buddies gutted car and I walk him bad on the street. He runs low low 12s at the track too.

If you rode in a mild 383 like I have as soon as I touche dthe gas and gave you the insta plant into the seat you would understand the torque thing. The 355 feels more linear.

If a 383 is built to drag race there is no comparrisson.

Both engines being built equally the 383 will produce more torque sooner.\

Build them to their potential and the 355 is left panting.

 

There is not a big difference, though I am not sure what you mean by a "388". Do you mean a 3.75" stroke and a "60 over" (4.060") bore? In general, I would strongly advise against that. 60 over on a stock small block will usually leave very thin cylinders with resultant poor ring seal and possible outright failure (especially with nitrous or a blower). If you have a lot of blocks to choose from and the ability to sonic check the bores along with a sophisticated machinist you may be able to have a 388 with acceptable wall thickness, but otherwise, stay with 30 over or 40 at most. And realize that once it's at 30 or 40 over there is no room for any additional overbore.

As far as a 3.48 v. a 3.75" stroke, I say go with the longer stroke provided you are going to replace the crank in either case. Not a huge power difference, but since the additional cost is minimal, why not?

Rich

 

It wont cost anymore to do a 383 than a 355 if you are putting a new rotating assembly in(forged) the components are virtually the same price. I just dont see why if you are going to replace the crank anyways, not to go with a 383. The difference will be that the 383 will be more streetable than the 355 with simular power, keep in mind though if both engines are build to the max the 383>355; what usually happens is the people that have the better running 355 just put better matched parts in their motor than that of the 383 owner.

 

Cola makes a 3.8" stroke crank that is supposed to give you a 388 when bored .030 over.

 

I was wondering if that's what he meant. If so, then I vote for the "388".

Rich

 

A freind of mine just bought one of those through GMPP and it is a very nice peice (1300$)

 

yep 3.8 stroke is what im doing. cola crank (3.8) lunati pro mod forged rods (6"), and je pistons. and it will have a 4.030 bore and i want to sprya a 200 shot. the heads are stock ported by loyd with 2.05 valves ( i want to see what a set of stock can do. and one of his cams a little bigger than the le3.

but it will all be forged

 

I ended up buying a Cola 3.50 inch 4340 forged crank when I could have gotten a stroker crank for the same amount. I've got some AFR LT4 210 heads so I have the heads fo the stroker but I am building a forced induction motor so I would rather put the extra money from the machining and clearancing of the stroker towards other parts such as the supercharger. To me, at this time, I just don't think that the little extra torque is worth the extra money to me right now. If I wasn't working on a strict budget, I would have built a stroker.

 

w/ a 6" rod, that compression height is going to be pretty short. id run a shorter rod and get some more piston in there. even w/o nitrous, when you make a piston that short it will have more of a tendancy to rock around at BDC and wear the rings out faster, combine that with nitrous and those rings being up high on the piston and its liable to burn up rings on the bottle. just my $.02

 

Just my opinion but I wouldnt waste all that extra money just to have 5 more cubes, I dont think it is worth and you may have a few fitment issues. Maybe you should think about a 396 or 408 they would cost about the same as the 388 or just .020 it over and a 3.75 crank for a 381 is you want to be different.

 

a larger stroke requires more air, more cam, more head, more intake to rev to the same point.

to make the same power, you dont have to rev as high.

a 355 and a 383 both revving to say 7000; the 383 will make more power assuming everything is correct.

 

I've got the same crank here and a block that I had to take to .035 over = approx 389 cubes. I'm going with a 5.85 rod and a 9.00 deck leaving me with a 1.250 ch. Actually found an off the shelf JE piston that works. I'm planning on spraying. From what I've seen unless you have more deck to work with, (which I don't, block had already been decked), a 5.7 inch rod gets you into custom piston territory. I too like the idea of having a larger compression heighth, especially for N20, but it just wouldn't work for me. JE pistons with that overbore for a 5.7" rod come in a 1.550 ch, wouldn't work. Only other option would be to go with a custom piston at 1.40 ch. To me the extra .15 isn't worth the extra money. FWIW I'm kind of like Rich, from what I've read the difference betwee rod length's is minimal. If i was going to run boost or blow I'd definitely want a thicker crown piston, I don't think it's as critical with N20, and the extra length of the rod somewhat offsets that factor.