I'm in the beginning stages of building a new motor right now, i have the bare block sitting in the car waiting to be pulled out for machining and for me to buy a new rotating assembly. the car is gonna be mostly for track but i will also drive it 2-3 days a week, and i know i'm not going to pass emissions because even if i go w/ a 355 i'm gonna have a custom cam grinded that's similar to the gm847. my goal is 400/400 NA to wheels minimum!! i would actually like to be closer to 460/460 but i don't know if thats possible with a 355 and only keeping it at 11.5cr tops! are those kind of possible with a 383 and stock heads? and also i've noticed that people are able to spin their 355's to 6500rpm and still make power! what is it about 383's that keeps them from making a lot of power up top?

 

you can do 400rw with LE2 heads and a GM847 cam..stock bottom end...not to mention i spun my stock bottom end to 6700rpms, 3555 fully forged/4 bolt mains/studs..i dont see why you cant se 7500rpms(stock pcm limited to 7k though)

 

well i'm not keeping the stock bottom end because i spun a rod bearing. but i basically i realized i could go 383 for around the same $ im spending so my ? is would i get more bang for the $ with a 383 or would i just get a tourqer that doesn't like high rpm?

 

It doesnt matter what "Forged Kit" you get and/or parts for the bottom end, the crank is the key piece for stroke. That determines lift durations, flow timing.. etc...

I dont know about 6700 RPMS on stock bearings... That might be a little to much.
I wouldnt go past 6200 on a Stock LT1 bottem, even with modified heads.

 

my engine had 30,000 miles on it when i pulled it out..bearings looked fine...my car has 30,019 miles on it..it had 27,000 when i did the heads/cam..the bearings looked fine...i beat the **** out of it every day....single stock timing chain too.

 

I'm partial to the 383 because of the nice torque at lower rpms...I went with very high quality parts back in 1995 and the bottom end is still running strong after 11 years...I only have to spin the thing to 6300 with my 226/234 cam and it flies for what it is...This car could easily be a DD and it gets 20 mpg on the highway...No secrets, just a very simple, streetable combo...

Don't get hung up on dyno numbers either...they are way too easy to manipulate and don't mean too much...You'd laugh at the numbers I put down...Dynos are for tuning...the track is the judge...

--Alan

 

The cam and heads are what keep the rpms down on the 383's. The stock heads have small intake runner's, around 170cc. Alot of it depends on if you have to have emission testing on the motor for the cam specs. I am one of the lucky few with NO EMISSION TESTING(NaNaNaNa....sorry couldn't control myself). I have a high winding 355 LT4 combo:
- 12.16:1 comp.
- Moded AFR 195cc LT4 heads
- Modified single plane intake(not a LT1 or LT4)
- 1250 cfm 4150 style TB
- DynaSpark opti
- Custom HR cam 288/292 adv. 259/263 @.050 110* LSA 110* Intake centerline
.640" int lift .620" exh lift
- Crane Pro series shaft mount rockers
- est. 617 HP and 502 lbs. ft. of TQ (close to within + or - 25 HP) at the flywheel

I make more HP than my old 383 and almost as much TQ all the way thru the rpm band.

 

thats exactly the kind of build that makes me want to go all out with a 355, i have another question tho, does the 355 have a broader power band because you can rev it out longer? or does a 383 have a broader power band because it takes longer to rev due to more rotating mass? i need an engine thats good all around but more so on the strip and on auto x track... i love the top end you can make with a big cam 355, bu could i make up for the low end torue it lacks with gear?

 

Easily you can make up for it with the right gearing. I am only running a stock 3.42 ratio rear gear. I have more TQ at 2000 than I did with peak TQ on the stock motor. My peak TQ now is at 5000 rpm and my peak HP is at 7000 rpm. But my HP hardly drops off all the way to 8500 rpm.
You can make a 383 rev just as high as the 350 with proper parts for the job. It will spin up just about as fast too, again depending on your components used. The biggest thing is to match your components together for the job you want it to do.

 

1997bird, what would you think of this set up? how would it perform?

-brand new block prepped by Dave Timmons (Mopar Engines West)

-scat forged steel crank

-scat forged rods probably I-beams

-JE pistons ( going for no more than 11.4-.5cr because of shitty gas in cali)

-clevite 77h bearings

-plasma moly file fit rings

-stock heads p&p fully(most likely) or 180cc CNC'd afr's (possibly)

-custom cam at least as large as the gm 847 or cc306 on most likely a 111-112lsa and matching springs

-1.6 nsa rr(not sure on brand yet)with 7/16" pushrods and hardened guideplates

-P&p stock intake

-58mm t.b.

-kooks stepped long tubes, no cats, coming out of true dual corsa's

*stock gearing in m6 tranny for now but 3.90 gears out back
*no a/c, no smog pump, and new k member so lets say 75lbs off the front end

 

you should get 195's or 210's on the heads, 180 is a bit small for 355/383 fully built

I made 407 RWHP and 396 RWTQ with 195 AFR's and a small *** cam from Comp cams and an unported LT4 intake (with 60 miles on the motor). Now if I were to complimet the heads with a better cam and P&P the intake, and maybe open up the heads a little more... probaly be looking at 440 RWHP.

 

I would stay with the 180 cc AFR Eliminator series heads. The stock heads are not recommended for more than 500 HP or 11.5:1 according to David Vizard, for crack prone issues. The AFR heads are about twice as thick as the stock heads for the deck thickness. Not only that but the AFR heads will out flow your fully ported stocker's. You have a solid build going for you here. Let me know if you are going with a 383 or 355 (sounds like this is your option) and I can put it into my dyno sim software and give you HP #'s and TQ #'s. Let me also know what you are going to use for rocker arms to design a proper cam for you(aluminum vs steel and brand name for strength factor's).

 

nothing is set in stone yet but i think i am going to end up getting afr's and possibly go 195's jus to have room to grow jus a little bit more..... i have also heard that even though the stock heads can flow pretty good they are not good for high cr because of the thinner decks.... i have been thinking about comp cam gold rr's... but for now why don't we call it a 355, with a gm847, comp cams gold nsa rr,

 

Comp Cams Pro magnums are also great

 

I put together a cam for you from one of my suppliers on cams.
- Adv. Dur 286/294 int/exh
- @.050 246/254 int/exh
- 112* LSA
- 112* int centerline
- .592" lift int & exh with 1.6 ratio rockers
- I would recommend a set of Comp Cam lifter's # 875-16 to handle the RPM

This cam should make around 523 HP at 6800 rpm and 480 lb. ft. of TQ at 5200 rpm with the above mentioned 355. This cam is designed more for your road course racing for better power coming off of the corner's. It will also be a pretty good drag race combo for you. I was useing the above mentioned AFR 195 cc Eliminator heads for the build. I would not go with the 210 cc AFR's, as advised by AFR on my 355 combo.

 

Is this rear HP or flywheel HP???? and did'nt the eliminator heads jsut come out?

 

This is Flywheel HP at sea level condition's. That is the only way the program computes things. And yes they did just come out into the magizines, but they started the new castings for these heads after Feb. of this year. I have been told this info by AFR while haveing them look for a set of my customer's cylinder heads.

 

Are those numbers with unmodified afr heads or are those numbers with a P&P? and what does the torque curve look like on it?

 

These number's were useing their published flow #'s that are right from AFR.
HP TQ
2000 127 334
2500 171 359
3000 214 375
3500 273 409
4000 339 425
4500 408 445
5000 430 476
5500 461 471
6000 494 464
6500 503 444
7000 520 415
7500 510 371

 

is that the cnc ported version from afr or the casted 195cc lt4 dtreet head? would i be able to modify my lt1 intake to fit on those heads and not cause a restriction?