A well Built 396 Lt1 vs. a well built 383 Lt1
 

Hi guys,

Pulled my engine and about to send off to machinist. My machinst says that I should stick with the 383 because in his experience, the 396 doesn't make that much more power.

How can this be when you step up from 350ci to 383, you get a nice boost? Isn't the same true when you step up to an additional 396ci?

Machinist also told me that a lt1 383 can compete with the LSI with really good flowing heads (above 275cfm) and the cc306 cam. Is that true?

The key to either build will be a set of good flowing heads and a cam that takes advantage of them.
Going from a 350 to a 383 gives a 33 c.i. gain.You are only gaining 13 c.i. from a 383 to a 396.A smaller gain.
Either one(383 or 396)will easily out perform a stock or mildly built LS1.
If you have awesome heads go with the 396.If you have mildly ported heads go with the 383.You need a flowsheet to know what you have.

96LT4 is correct.

I don't know about your machinest experience with 3.875 stroke engines (396) not making the power a 3.75 (383) stroke engine does. That is bad advice and not even close to right.

All things being equal between the 2 engines they will both make the same HP. The 396 will make peak HP at a lower RPM and will make more TQ (and therefore more HP) until the peak.

It's all in the combination. Both can be made to do what ever you want (and well beyond) if you have the $$$.

A 396 will require more work and cost more to build. There is more grinding on the block for rod clearance and less availibility of parts for 3.875 stroke engines.

A 383 is easy. There are 100 different "off the shelf" ways to build a 3.75 stroke engine.

A really good set of ported LTX heads and a CC306 on a 383 or 396 inch LTX would put you well over 450HP at the crank (more depending on how good the heads are). Stock, Bolt on or even mildy modified LS1's would be lunch meat... But be aware that can change in a hurry with an LSX engine. The parts selection they have available to modify their engine platform is unreal and once they start modifying things for real, the HP numbers go up in a hurry.
Will

Unless you've got unlimited funds, stick with the 383. If you have unlimited funds, then a completely different path is in order. :smash: :smash:

Smaller displacement increase, smaller gain in comparison. In that sense he is correct. A slightly different combo would be in order if you went to 396...better heads/cam.

An LT4 can compete with an early stock LS1, modifying your engine to 383/396 with the right heads and cam can whip an LS1.

I think like most things, it all depends on how much $ you want to spend, because you can get a cast 383, but 396 only forged. IF money is no object, then why not get more cubes, plus 396 is Chevy #.

I decided to go w/a 396 mainly because 383s are everywhere now.
The machinist had to clearance the block for the rods and that was it, no filling the block stuff you hear. I went with the Lunati "compstar" brand forged crank and rods. My machinist is grouchy old guy who's satisfied with virutually nothing, and felt they did a good job with the crank, I was surprised. He rebalanced the rods and balanced the rotating assym for me. I could have done a 383 cheaper, but if you went with a decent quality forged rotating assembly, your cost would be pretty near the same. Toughest part of doing the 396 is there is not a ton of cheap cranks and rods out there for it, what is available tends to be the very expensive stuff. I really couldn't afford the Callies Dragon slayer crank, but I'm very happy with what I got for the money.
Also, I went as high as I could on compression for pump gas to get the most out of it. It's not my DD anymore, I think my static comp is about 11.75. And Datamaster logs show I'm not getting any knock on 93 octane.

I finally ordered larger injectors today, but I've put nearly 1k miles on it as it is, and it runs like a scalded dog as is. I have to short shift because I'm going lean at 5300, but I cannot tell you how impressed I am with the torque produced by a stroker. Puts a big $%# eating grin on your face.

If you want more detail pm me and I'll give you more detail on the parts went with.

Edit: Just wanted to add the old saying that it'll cost three times as much, and take three times as long, was dead nuts on.
I was originally thinking 3-4k and about six months (in reality 11k (including clutch and flywheel)and 16mos, ). But I just kept wanting to go farther though. You know the saying, if your gonna be a bear, be a grizzly. And it all started with a blown head gasket :)

:iagree: True-er words have NEVER been spoken!

R/Noland

i took a different route when a buddy decided he wanted a sh*t kicker c-4. we just went to scott schaffrof in ny . and bought one of his 472in dart blk small blk for 9500. best money he ever spent . car just flys. still gets 21mpg on the freeway.i would have to get ahold of him to find out the exact rwhp but believe it was in the 520-540 range. thing is a sleeper too as the cam isnt that big. just a thought you might want to concider:cheers:

Yeah, but there talking about LTx's. Biggest I have heard is 421 from CXI racing.

Thanks Guys,

Now, I'm starting to wonder about my machinst.:toetap: Seems like he just wants to go the popular and easy route. . . .damn geezer...:lol:

Hey F1FAN Could you PM the parts you went with if you have time. I am really interested in your package. Did you dyno it?

Did you have to go with a smaller base cam? I see that eagle sells a kit that doesn't require a small base cirlce cam.

Ok, here's what went into the 396 build

Block decked .017 to true up
Bored/honed with plates
size rods
Align hone
Clearanced for rods (~$120)

Compstar 3.875 forged crank
Callies p/n CAM113-CS
Compstar 5.850 forged rods
Callies p/n CSA5850DS2A2AH
SRP 4.030 forged pistons (-14cc relief)
(ACL bearings, total seal rings)
ARP main studs 134-5601

ARP head bolts 134-2101
Heads ported by Total Engine Airflow (52cc)
Milled .010 originally during first build up,
milled .020 on rebuild (plus typical "stage 3" type stuff)
Comp 1.6 magnum rockers
Comp 3/8 threaded magnum rocker studs
MLS .027 steel head gaskets
LT1 Intake, milled to match head milling and also port matched
GM intake gaskets
Arizona speed and marine 58mm throttle body
(I suggest not buying theirs if your car has ASR on it)

Canton 7" Road race oil pan 15-240T
Felpro blue pan gasket
Canton HV oil pump 21-560
Canton pickup 20-079

Comp magnum pushrods
Cloyes HD timing set
Comp cams magnum roller lifters
Comp cams 236/242 custom grind 112 LSA (actually an off the shelf cam from Thunder Racing)
Bosch 42lb Injectors on order
Spec stage 2 clutch (Was supposed to be sent neutral balanced, was 17g off!)
Spec aluminum flywheel
TPIS longtube headers
Random tech cats
X-pipe
Borla 2.75" catback
B&M Ripper shifter

Misc:
EGR removed
Moroso 8mm wires
Fueltronix fuel pump
Tuning
New Opti cap/rotor
Cut air lid
Descreened MAF

And probably some other stuff I forgot

No dyno yet since I was still waiting on injectors, hope to do that soon though

fwiw, my machinists advice on Eagle kits is that they are typcially so far out of balance, that
by the time you pay for all the corrective machining, you could have bought better parts to start with
and less machinist time involved.

Any oiling issues etc?
How do you like the TEA head, I hear they do good work? Flow #s?

No oiling issues that I'm aware of.

I bought the car from my friend who originally had the work done on the heads by TEA, but I sent them back in and had them cleaned up, new valve job, guides, milling, etc. and port matched the intake

I think they did pretty good work. I think if I was starting from scratch, I might go with the AFR heads though.

Here's the numbers from their flow sheet
.2 139/111
.3 203/168
.4 245/200
.5 269/221
.550 268/230
.6 266/235

F1Fan...AFR heads; with the parts you already have, would make some big numbers for sure. I don't know if they'll mill to a 52CC chamber though. How much compression are you running with those pistons.

:chevy

The machinist who did the block measured them while we were there, and they came out to 52.2cc

Static CR I believe is in the 11.75 range, and the dynamic came out in the 8.5-8.7 range.

My intent was go as high as I could on pump gas.

Update:

I decided to go with the Eagle forged 396 kit. The block is being machined. The Eagle kit was slightly off balance and that is getting fixed. It was not expensive (60.00). I will start posting pictures when I get it back. I stuck with the forged pistons, even though I argued for the Hypers because I hate oil consumption. Machinst told me that if I break it in properly, there will be no oil burning at all. (:skep: ) really?

I am also looking at the LE2 package to go along with the build. And shorty headers.

Are 30lb injectors ok, or do I need larger?

30 lb should be fine; it's in the tune. Long-Tube headers make more power under the peak. Rings are going to determine the oil consumption. Good for you going 396"... It should make some good power. While it's only a small displacement increase, it's done with the Stroke, where a small increase makes a big difference. Good luck to you...

:chevy

You will be restricting a lot of power by not going with long tubes. My guess with your set up is at least 30hp. You can get high flow cats if clean air is your concern. No headers on your set up is like having pasta with out the gravy. It will still be good but no where near its potential. I learned this after my H/C install. Took my car for test drive after dynoed at 343hp. I was disappointed, left the car at the shop to have cats removed and replaced with headers and x pipe. Dynoed it (365 rwhp) and I felt the differece at top end.

I built a LT4/383 to turn 7,500 RPM. It made 430 RWHP with a conservative street tune and too small of injectors. It still had 'too much' low-end torque, yet it would PULL HARD forever in any gear.
With modern head porting and camshaft profiling, excessive cubic inches is unnecessary in a fairly well balanced street car (but with obvious traction limitations).