ok i have been buying parts and getting my new TFS heads done at A.I.. Ron called me the other day asking about block specs. seeing as i am wanting to get as much as possiable out of this combo as possiable, i told him i would get the block done to his specs. he then asks "this is for a 383", i told him "no a 396". he then tells me it would be better to build a 383 instead, due to piston speed. i then log on here and search for piston speed for 383 vs 396. i cant find but a small amount of info on that topic. i did find a bunch of posts about folks building a large stroker and the heads cant possiably feed it. so it was a waste of money and time to go that big for them. so that is the back ground and here are the questions

1. how much more piston speed does a 396 have over a 383?
2. can A.I's 210 TFS with these numbers http://advancedinduction.com/AiProductsTFSAFRLTx.html
support a 396 to make full use of that extra cubic inch advantage?
3. or would a 383 be able to make just as much hp/tq.


i would have talked to ron about it in depth but long distance on a cell phone sucks, as far as cost goes. i trust ron and phill with the heads and motor specs, dont get me wrong. phill even made my head hurt when i went down there to drop off my AFR'S . i would just like to understand the factor of piston speed and the heads being or not being able to feed the 396 over the 383. thanks for any help and pointers.

wow this is my 444 post, does that make me smarter than people with a lower post count than me LMAO some folks do think that way (sorry had to drop that in here)

 

330CFM is capable of 680FWHP if everything else is spot on but it HAS to be right.
Piston speed is not much of a concern with good pistons and your RPM capability. If ya were going to 8500RPM it might be. There are plenty of 406's turning 7500 every day. Piston speed and rod length has a lot to do with the intake flow also.
Piston speed for a 383 with a 5.7 rod is 4688@7500 and a 396 with a 6" rod is 4844@7500.

 

ok let me see if i took al of your response in.
(oh by the way that 330 number is off the raised runner lt4 heads mine are a little lower than that, no biggie though) the differance in piston speed is so close that it really isnt a issue unless you spin up really high (and i wont be) i wll be running a decent shot of nitrous (actually 2 smaller shots,125/175) so i will be trying to get a 5.85 rod in there with a custom cut piston, so the rings wont be in the pin. so my speed will be slower than the 6 inch rod right? someone told me that a 383 vs 396 with all factors the same. the 396 will produce 13.4 more hp than the 383. does that sound right? i am at the point where it is time to order the crank,rods and pistons , so i am trying to make sure i dont change my mind after i get them in hand. thanks for the info racer, your making me lean towards the 396 more

 

A 396 will have a fatter torque curve but will make ~the same peak hp, all else being equal. It will be a little quicker and maybe a touch faster in the 1/4m. Depending on the parts chosen, there may be issues with rod clearance on a 396, that's the main reason to do the 383 instead. Easier to assemble without hassles.

Rich

 

The piston speed is the same with a 5.85 or a 6.0 rod.
Don't know 'bout the 13.4HP reading. A 396 built RIGHT should be capable of close to 800FWHP on motor some of the Pro Stock trucks were making around 1100FWHP@400CID(not anything like an LT1) so can't see the 13.4 at all.
A 383 should make around 770 all else being equal. The 396 would make a TAD more torque.
Your heads are going to be the difference.

 

LR: by "all else being equal", I meant ALL ELSE, including the heads. If all else is really equal would you really expect to see 30hp more with the 396? My own experience contradicts this, so I am kinda surprised. Over the winter, we put a new bottom end in a buddys SBF. Went from a 331 to a 347 and left EVERYTHING else the same. Made more torque everywhere but hp was up by just 2-3hp. Just what we expected. We were going to also change the cam, but money and time got short so the rest of the motor is the same other than the new RA.

BTW: it's a stock block and we had to grind off a couple of pounds of metal for the extra clearance. What a PITA, even taking turns.

Rich

 

"All else being equal" means build BOTH to a max effort and not try to use the same cam and such on an engine that it is not designed for.
I am not saying to build a 383 and it does pretty good then pull it down and put in a 396 rotating assy and don't do anything with the heads,cam and exhaust. That DON'T work on a MAX effort. To me that would be throwing money down a rat hole as ya could have left it alone and been just as fast.

1100FWHP from 400CID should let it be known what can be done. They were BIG bore engines and shorter that 3.875 stroke and turn some BIG RPM's.

BTW it is easier to do a 356 (.030 over 351)Windsor than to do a 347 unless it's 8.200 deck height class rules. The heads fit but need to be way bigger.

 

Well, it's true that a good big un beats a good little un every time IOW, your points are very well taken and I couldn't agree more.

But from his post, it looks like "jason" is in the same boat that many of us are, especially with an LT1. The combination of budget and available parts conspire to make the combo a big compromise and far from optimized. Most of the time, we are working under a variety of other constraints as well. In his case, he already has heads. Don't know if he has a cam or not. I am guessing he will be using an OEM intake. These are going to minimize the differences bewteen the 383 and 396.

As far as the Fords go, also good points - you obviously have dealt with this stuff. There too though, we weren't starting with a clean sheet. My buddy is racing in a local class which is described here: www.momsracing.com There aren't a lot of rules, but like most of us, his racing budget is far from unlimited. He needed to replace his crank, it had developed cracks along the fillet radius. While we were at it, we figured why not get a few extra cubes. As with other "simple" projects, various problems cropped up and time started to get short. So did money. New heads were never on the table, and with time and money issues, the cam we had planned on also went by the wayside.

LR: you are in the performance business? If so, I bet one the first things that comes up with a customer are the questions of how much money and how much time? When I look at professional racing, I am impressed with the teams that succeed without the biggest budget, through brainpower and good management and a realistic assesment of what is needed to win in whatever class they are in. At the extreme level, there is F1. Ferrari, Honda, and especially Toyota have HUGE budgets. BMW and Mercedes are also spending the long buck. Yet Renault, with reportedly the lowest budget of the big boys, is dominating.

Rich

 

This and the extra expense is why I don't build 396's.

Those teams are hungry. They are there to prove a point and that point is they are the BEST. That is what drives me and most racers.
The money thing is I tell them up front what it really gonna cost instead of a "front" figure and keep adding on.
Time is how much time it takes the shop and UPS to get me what I need and another 2 weeks if it's just a build and not an install. If I pulled it I allow 4 days R&R. If they pulled it then want me to put it back the time is open,could take me two weeks to figure out what they did.

On that 356 Ford, ya can use a stock block(pre '94 preferred), stock crank,truck rods and a good set of pistons a flat solid cam TFS twisted wedge and a Victor Jr and have a 10.8 sec ride on motor in a 3100lb car and it will do it for "several" years. Got one that runs 10.80's 1/4 in a 'stang and a 10psi Vortec in a 1gen Lightning that is daily driven that runs 7.30's@4700lbs in the 1/8 both built the way listed. The stock stuff is tough if built correctly.