ok so i have a badly worn out 350 that's already .060 over, i think i'm just going to start from scratch on this one. the goal is a 383 that will run around 450 peak crank hp, and be strong enough for a 100 shot of NOS and 8k rpms. the list so far is a bowtie block .030 over and a 4340 forged rotating assembly. the questions are; what engine heads will let me safely run 11:1 comp on pump gas (93 octane 64cc cambers with flat top pistons), what cam with survive 8k rpms and keep me making power to he top (goal is to peak at 7-7.5), what is the best brand to go with on the rotating assy, and finaly is this doable at $6,000. thanks for the input guys

 

You have some confusing criteria there. 450 crank hp is child's play with a 383, no need to rev to 8000 for that. And BTW, no 8000 rpm engine is going to fit with a $6k budget, not even close. 6000 rpm is all you need for your hp goal.
Based on the little info we have here, this is all I can recommend at this point: Buy the basic crate 383 from GM, swap cams, install your 100 shot, dyno tune it, and live happily.

 

+1

As for the RPM requirement you can order AFR heads with a custom arrangement with 8mm valve guides so you can run the lightweight Z06 valves with some comp 918 beehive style springs and either stock LS1 or titanium retainers. With these springs an installed height of 1.75" should easily cover the 8000 RPM requirement, assuming you run the light valves.

As far as extending your peak power upwards to anything near 8000 RPM, that will require many major changes, and bust your budget. You may be able to find a used dirt racing motor for sale that will do it, but don't expect it to be streetable.

Edit: Forgot about the camshaft. For the 8000 RPM range you will need a camshaft with lazy closing ramps and a relatively low lift for the given duration you choose. This allows the springs to control the valves at high speeds.
Your lifters need to be either solid rollers, or hydraulic rollers with less than 0.005" preload when installed.

 

ok, some decent info but not what i'm really looking for, as for 8k rpms at $6000 i know i can be done as i have seen it done, i don't need a honda style 8k rever, just once in a blue moon to push a few more ponies when the nos is going (that should also take care of air flow at 8k as the additional oxygen released by the nitrous oxide will be sufficient) for street use 6.5k would be the highest she will spin, any more info you need just let me know (i have no issue with more than 450 crank hp, in fact ill trade a few low end horses for that 8k red-line, as long as i can keep budget)

 

I wish you luck. And I suggest you read up on internal combustion engine theory and study some existing builds for a year or so before diving into your project.

 

well as helpful as you have been is there anyone with some real ideas?

 

FYI, with the use of N2O your optimum shift RPM will go DOWN by 500 to 1000 RPM. The more N2O you use, the lower the optimum RPM drops. N2O is not for extending the RPM range.

You said you wanted "real ideas", but I don't think you gave any extra indication of what they might be.
Hitting the occasional high RPM is a valvetrain control issue, and I covered that.

A 300 HP engine can hit 8000 RPM, or a 600 HP engine can hit 8000 RPM if the valvetrain maintains control. The only question is, does it make sense to do so?
The use of heavy valves & valvetrain, or an aggressive camshaft ramp will make it harder to control the valves at the higher engine speeds.

Put a great valvetrain on a stock 350 and you'll probably hit 8000 RPM a couple of times before the rod bolts let go, but that's a reliability issue.

 

To get a 383 to peak in the 7000-7500 rpm will require a very large port head, large solid roller and an expensive valvetrain. Thats probably 3000 bucks right there. If you can do the rest for 3g i'd be impressed.

Peak at 7500 lets say and beable to shift by 8K rpm will not be very streetable. That will make more like 550whp rather than 450 crank. May not even be pump gas friendly at that point. Your talking a cam with duration at .050 probably around 265-270? Maybe more. Something like a 230cc-240cc head i'm guessing.

Nitrous has little to do with keeping airflow at 8K rpms. TO pull that off you need to move ALOT of air through the heads/intake. Nitrous only flows as good as the air its riding in. It will release more o2 in the chamber to make more power but doesnt mean you can pull more rpm. In fact most nitrous motors i've seen peak earlier compared to the n/a setup.

shifting by 6500 rpm on the street really isnt all that great either for a motor that peaks by 7500. Thats severely short shifting a setup like that.

You have a radical goal here that I highly doubt can be done for 6K let alone remain streetable enough.

IMO, stick to a setup that can turn 7000 rpm, peak by 6500 rpm so you shift by 6800-7000. 210cc head, low 240's duration hyd roller or 250's solid and enjoy 550hp crank easily, maybe closer to 575/600. Much cheaper to do, much more realistic and completely destroys your goal of 450hp while being much more reliable.


if you want 8-9K rpm screamer, thats nascar type stuff and BIG bucks. There is a guy on here with a 8k+ rpm motor thats based on SB2 stuff thats fairly expensive but exactly what you need for that rpm. He's on LS1tech too and I think posted there more than here.

 

If you want your motor to make power and shift in the 8K plus range than you are going to have to fork over the money for a custom camshaft and the proper lightweight valve train components. Then you are going to have to spend the money on a good light weight rotating assembly. It will get expensive real fast.

I think you will blow right by that $6000 budget in a heart beat if you want to build a motor that will last a few miles. Don't forget the machine shop costs to build that type of motor. By the way what transmission are you going to use?

 

ok now thats what i wanted, so i fear 8k is dead dream it seems you know your stuff. if you had 6,000 wanted a real thumper that was streetable what would you do? it will have some miles put on it so keep gas in mind. sorry for the dumb questions but i hale from the world of Honda so 8k doesn't seem so high to me.

 

V8's just normally dont rev that high. 6K budget for a 383 that wants to rev alittle?
Might beable to do an all forged shortblock/AFR 195 heads with 8019 spring upgrade or 210's with same spring or brodix race rites 200cc heads, or similar, and cam in the 236/242 range, 110 lsa or so.

Carb or EFI? EFI will be more money i believe but is nicer in the end. Stealth ram is probably the best bang for the buck available. Carb, get a victor jr and a 750 cfm carb.

Setup like that will do darn near 500-525 crank hp and live on 93 octane at 11 to 1 compression. It will peak hp near 6400 rpm and hold that fairly well til 6600 rpm or so and shift by 6800. Thats screaming pretty good for a 383.

Your used to honda 8k+ rpm, but its no comparison to a 383 running at 6500+. 6500 + on a sbc will seem like 8K+ on a honda.

Basically similar to my 383 motor i had 2 years ago. AFR 195 cc heads, forged shortblock, 230/245 cam on a 109 lsa, stealth ram EFI setup, etc etc. Peaked at 6250 but held power to 6500-6600 and I could shift by 6800. I have taken it to 7000 no problem. Boy that is fun to hear that motor hit 7K. Something like that pan to intake could be done for 6-8 grand or so depending where you get your parts and what parts you get


1989GTATransAM above has a nasty little 369 motor that will rev to 7000 rpm. Its got a 233/233 cam in it with AFR competition ported 195's I believe. Its got a Dart SHP block which is nice to have but will blow your 6K budget away I think since its 1800 by itself all machined. But that motor made 535hp on crank so its gonna be a BLAST to drive

 

damn, that sounds like a monster, thanks ill start putting a grocery list together. will the stock rear end (25 anniversary ed. camaro RS) hold up for that? the trany is a newly rebuilt 5spd, and the idea was to carb her since the electrical systems are all junk in that car.

 

Start saving you $$$ for some driveline upgrades behind a 500ft/lb 383

 

Yes, it has the AFR 195 Competition heads right out of the box. Also has the titanium retainer and keeper up grades to help keep the valve train light and the AFR rev-kit for insurance.

The reasons I asked about the transmission is if it is a 700R4 being used it will not like the high rpm's and you will have to put some money into it for it to have any kind of life.

 

the trany has no labels and was re-imprinted by the shop that redid it, but ill try to find the serial. as for the stock rear end and the u brackets on the drive shaft how will they hold up? im not going to be driving like mad all the time just once in a while. i guess the last thing is the brakes, should i put money into a rear drum to disk swap or better front rotors and calipers?

 

one more thing seeing as afr 210cc are in the same price range wouldn't they be a better buy?

 

Yes they would be much better choice for over 6500 rpm

 

i am running a 383 efi, and makes 480 hp at 5800 rpm and 495 ft lbs of torque way down low and still maintain 19 ish mpg on the streets. What kind of combo you looking for?

 

that's in the ball park, just need something that gets half decent mileage but really pulls when i need it to, mind listing you parts and final cost?

 

If you really want a 383 go for it but if you want more and sooner or later you will. Just save your pennies and build a real engine starting with a all Billet aluminum big block chevy block from dart. Add some space may be 10.2 deck with a 4.6 bore. Then stuff it with as much 40130 steel you find. Gobs of torque and horse power. A lot of money yes. A lot of fun yes. A lot of power yes. A better choice in the long run.

 

If you're interested, edelbrock makes a top end kit that revs out to like 6500 RPM and builds 460 horses/460 ft lbs for just under 2 grand.

 

ill look into that edelbrock kit, and i wish a big block were possible, but I'm pushing the budget as it is. seeing as my daily drive now is a 4cl altima i think it will take some time to get board of 500-something ft/lbs of tq.

 

what about finding an LS1 or 5.3/6.0 liter truck motor and do a cam only swap? Make 400whp easier and cheaper than the 383 and run smoother too boot.

 

"If you're interested, edelbrock makes a top end kit that revs out to like 6500 RPM and builds 460 horses/460 ft lbs for just under 2 grand. "

I would be very wary of Edelbrock's claims.

 

i don't want the head ache of trying to get a wiring harness and ecu hooked up, the car has no harness now and already has a low pressure fuel pump, i also i love to old school 383 sound, but if it is significantly cheaper, with the ecu and harness, ill give it a look