Blackdog36

iTrader: (3)

Hi, I've been contemplating by engine build for a while but am to point where I need to make a decision and start buying some parts. I'm overhauling my 92 camaro and saving the stock drivetrain. Will be installing new parts for pretty much everything (engine, intake, transmission, heads, rear end, radiator, etc.)

I'm debating between a 383 and a 421 SBC. Building a 421 is just a little more than doing a 383 so the larger engine is tempting. I'm concerned that the 421 would have too much power and I would go quicker than 11.5 seconds in the 1/4 mile. Car would mainly be street with occasional trip to drag strip. A 1/8 strip is half hour from me with a 1/4 strip little over an hour away. I do not want a roll cage in my car hence reason to stay under 11.5 seconds.

Below are my engine combos for both the 383 and 421 builds. I based power levels off of the "ten times the torque" article and other info I have come across. Both builds would have built 4L60E, Dana S60 with 3.54 gears and 26" tires. 383 build would do better with 3.73 gears but I would like lower cruise rpm of the 3.54's. Both would not rev past 6,000 rpm.

383 build - 350 1 piece RMS 4 bolt block, AFR 195 Comp heads, Comp Cam XFI 280, 460 HP @ 5,400 rpm, 550 TQ @ 4,400 rpm

421 build - Dart SHP, AFR 210 heads, Comp Cam XFI 292, 510 HP @ 5,200 rpm, 610 TQ @ 4,200 rpm.

People on this website with strong 383 TPI's seem to be running low to mid 12's. Some also claim high 11's with strong 350's and 383's. I feel that with the 383 build, good traction, tune and shifting that I should be able to do high 11's. Times seem all over the place from people. Per online calculator and 3,500 lbs, 530 HP at flywheel or 450 HP at wheel will get me to 11.5 seconds. Would the 421 build push me to and past 11.5 seconds? Should I just build the 383 and still have a very capable car?

Blackdog36

iTrader: (3)

I found a post by 88BlackZ-51 discussing his old and new 420 SBC. His old engine combo was a 420 SBC from Lingenfelter Performance. The post reference and engine combination and power levels are below.
https://www.thirdgen.org/forums/alte...421-alive.html

420 Cubic Inches
3.875" stroke Callies crank
Oliver 5.875" rods
11: 1 compression, custom forged pistons.
Used a Bowtie engine block
Comp Cams mechanical roller cam: 236/244 @ .050, .549/.549 lift, 110 deg lobe sep, 1.5 roller rocker arms by Comp Cams.
Lingenfelter ported AFR 190 aluminum heads
SuperRam intake, base, and 58mm throttle body, controlled by DFI using 36lb/hr injectors.

Ran test on 1-7/8" open headers.

RPM TQ HP
1600 407 124
2000 415 158
2500 478 228
3000 484 277
3500 515 343
4000 534 407
4500 543 465
5000 530505
5500 498 525
5750 460 508

This combo has a small and less flowing head than I would use. Also, the superram will have a peak TQ and HP 100-200 rpm higher than my FIRST. The cam is similar. I'm thinking that my combo would make a little more power since my heads and FIRST intake flow more air. The above combo is right at 530 HP peak. A 421 FIRST combo should be very close to 11.5 seconds in the 1/4.

88BlackZ-51 has another post where he dynos his new 421 SBC with AFR Comp 195's and miniram intake. Below is link and dyno results from his second run. He is shy of 450 HP wheel that would get him to 11.5 seconds. His heads might be a tad small for the miniram so he could be losing some HP up top. His results though could be more what I would be looking at with FIRST intake.
https://www.thirdgen.org/forums/alte...-421-dyno.html
434rwhp@5900
470rwtq@4000

Even if my 421 SBC First build makes enough power to get 11.5 seconds in the 1/4, couldn't I always run a slower tune or run the car so I go slower at around 11.75 seconds? Don't people do this a lot to hit certain bracket times? My estimated HP limits to hit 11.5 seconds in the 1/4 are based upon a car weight of 3,500 lbs. Best I can find is that 92 Z-28 curb weight is 3,273 plus add 75lbs for 3/4 tank and 150 lbs for me which totals 3,498? Couldn't I always add a few sand bags in the trunk? Adding 100 more lbs to yield 3,600 lbs would take 20 HP more to hit 11.5 seconds which equates to a time difference of 0.10 second difference.

AlkyIROC

The only way you'll really know how fast you are in the 1/4 mile is to get onto a track. There are too many factors to determine what you will run. There's always going to be a best case scenario but very few cars will ever be able to do that. Lots of HP but poor suspension or traction and you'll never get out of the 12's.

It's also a package deal. Build a powerful engine but ignore the rest of the driveline and all that power means nothing. Start at the back and work your way forward. A powerful engine should be the last thing you put into the car.

Never quote HP or torque numbers unless you have dyno sheets to back up the claims. You have have 2 people build identical engines and they'll perform differently.

articwhiteZ

iTrader: (56)

go with the 421.. you will be glad ya did..

anything in the 3.875 to 4" stoke..
but stay away from the small heads (under 220's)
after all a 420 wants a good set of heads..

383's are the 350's of the 60's/70's

Orr89RocZ

iTrader: (20)

383 combo you mention should easily go 11.5 with afr 195's. Dont need the comp heads either.
383 should be much cheaper. Shp block is adding 1700 machined. If you can get a oem roller block late model that would be good bang for buck.

Smaller cubes should get better mpg to.

If you did a 421 keep same 280 xfi cam and use 210 afr heads. It will idle more smoothly than the 383 with same cam. It should drive very well and make much more trq. Thats advantage of more cubes they can make the same power as the 383 but require less rpm and do it more smoothly.
Et is mainly getting car to come off the line. You'll have the power easily to trap 117-118 which will get you 11.5 but needs a 1.5x 60 foot.
At that weight you only need 375-390 whp to get there. Both combos will do it easily

heavy_chevy29

i know you are looking to stay mostly a street car but i would go with the bigger engine. i ran my 434 on the street for quite a while. it was a total street car with ttops, full interior, and full exhaust. car ran low 11.7- really high 11.6. keep in mind it was carbed and ive never used tpi . it was great on the street. i had alot of fun with it. it is now a dedicated drag car so its a totally different animal. with that being said i would agree with using a 235-245 head on that motor. i think the limiting factor would be the tpi. you can always slow it down with the tuneup. the bigger motor will make more torque and give way more options in the future if you decide to race more. if i were you i wouldnt be so put off by the thought of a cage. they really add a ton of rigidity to these cars. talk to a good chassis shop. there are plenty of option for side bars that will be both strong and comfortable for street driving.

Blackdog36

iTrader: (3)

Thank you for the replies, I appreciate it. I'm still up in the air. I know comparable dyno numbers will not be same as real world but need something for a baseline. Going from 383 to 421 will cost more. Figure $1,700 more for block with upgraded lifters, $700 for forged crankshaft and $500 more for heads which totals $2,900. I don't think I will be able to get car completed this year anyways so saving the money will not make it where I could drive it this fall.

383's seem tame compared to what everyone else is building now but that combo would still make a lot of power. I still could have fun at track trying to get high 11's and cruise around the area and to out of state shows. I'm already in pretty deep $$ wise, don't know if I want to keep going. Figured I would get the AFR 195 comps to maximize the build even if a little overkill and allow me to grow in the future.

I don't know if my ego is getting best of myself at this point and I'm more eager to get a Dart block just for the sake of it. With the 383 I should be able to get a little better traction and I would have all supporting mods to make that happen for a good combo.

LB9GTA

iTrader: (1)

My old 383 with afr 195 eliminators with lt1 intake,1 5/8 shorty headers, open exhaust, 3.73 gears, 280xfi flat tappet went 12.09@110 and 11.0@125 with a 165hp shot of dry nitrous.
Bottom end was cast crank,stock 5.7 rods with hyper Pistons.

You could always add nitrous if you need a cheap way to go faster.

Orr89RocZ

iTrader: (20)

It costs more but build what you want. If you are deadset on dart block then go 406-421.

Like said you can always take power out of the motor if you go to fast. Mild driver would be that 280 xfi cam and afr 210's.
My old turbo motor was a 400" with similar cam and afr 195's. Idled smooth and was very driveable. Nice low rpm setup

86LG4Bird

iTrader: (1)

You'd really have to do something wrong in the build to not be running 11.5 or better in a 3rd Gen with a 383. Do it right and you'll have more torque than you'll ever be able to use on the street.
That's your logical answer. Anybody that doesn't feel that can be easily accomplished has no business investing in high dollar parts.

But..........I can also understand the "cool" factor of having a Dart block and big cubes. If the money is no object, have at it

paul_huryk

Dart makes SHP short blocks in 377, 400, and 427 ci sizes all ready to slap heads and valvetrain in...

There is no reason why a 460hp 383 can't run well into the 11's at around 120mph. And a 525hp 421 should be a high10 second car with the right gearing and traction.

Blackdog36

iTrader: (3)

Thanks again for the responses. For the 421, looks like you can only get a forged rotating assembly. I think the parts although nice would be overkill for a 421 build with a FIRST intake. I could split the middle and get a Dart block with cheaper rotating assembly and go 407. This would cost about $1,700 more. The 407 would make peak TQ around same rpm as the 383 at 4,400 rpm. That is really tempting but the 383 would still be very powerful and a well matched combination since I will have all supporting upgrades (transmission, suspension, rear end, etc). The 383 is also more than I was initially thinking about when I bought the car. I could have lots of fun with the 383 and 3.73 gears on the street or at track. Think I will go with the 383 and save some $$ that can be put to something else. Seeing how far I can go into 11's will be fun also : )

mw66nova

iTrader: (13)

a 350 will get you to your goals with proper attention to converter, gearing, and weight. a 383 should burp and fart it's way to an 11.50. 400+ cubes with an aftermarket block to get there just screams you have more money than sense to me

86LG4Bird

iTrader: (1)

Exactly.

And did I interpret correctly in Post 12 that you wish to run a cast rotating assembly?? ie. an AFTERMARKET cast stroker??

You'd be better off with a STOCK GM shortblock! .........which is exactly what I'm running, to the tune of high 10's / low 11's NA with a rebuilt stock bottom 350 in a 3800 lb car

DIGGLER

iTrader: (1)

it would be kindof a shame to top a 421 with 210 afrs with any sort of tpi. thats a 10 sec. ride with a cork stuck in its mouth.
you could do a stock shortblock like the guys above said and still get it to go 11.5's no problem. spend the money you saved on the engine on your suspension/tires.

articwhiteZ

iTrader: (56)

lol.yes..but... a 350 will never make 400 fpt at 2200 RPM..thats why the guys who have 421/427 sbc like them so much...

i did the 383 thing for a few years...running 11.70 on eng and 10.50 with NOS. and it was fun...but ya always want to go faster..just sayn.

my 427 sbc is the last small block im ever playing with...572's from GM are cheap now..

88BlackZ-51

iTrader: (2)

I wouldn't do a FIRST intake, but that's me. The day of the dyno, I had an exhaust leak and the car wasn't fully tuned. 450 rwhp and 485 rwtq were the numbers with the small 195's. I then sold the 195's and bought some 220's, but the numbers are unknown with those heads. I would expect another 25-40 rwhp with the 220's!

The cam was a 236/242 which was small for those cubes.......The combo was amazing in traffic and had amazing street manners!!!

And TORQUE everywhere in the power band even with a Miniram! The car would have been useless on the street with any runners longer then the Miniram.

I was impressed with the Miniram. What a great all around intake manifold....

The car didn't go to the track, but it felt like a 124-127 mph car. My C4 was light.

If I want a set up AFR's send me a pm. I can get you a deal on some.

Later!

antman89iroc

414 here. 4.125x3.875. AFR 210's 236/242 hyd roller on 112. HSR intake 36# with a stock TB (for now) Idles great @ 900 with a little lope but not too choppy. No dyno numbers but went 8.1-1/8th @ 89 on a soft launch and an unfinished tune. Full street car with ac, power brakes, cruise etc. It's a daily driver and pulls 5th @ 1500 cruises very nice @ 22-2500. Red line is 55-5800. Even though it's a fairly mild build I went with a SHP block, callies crank and rods and forged pistons. Bottom end is stout and can easily take a 200 shot. At first I thought I'd save some money on a scat crank or possibly even a cast crank. But at the end of the project I'm in ~$10k so "saving" bucks on something as important as the bottom end of the motors seems foolish in hindsite so I'm glad I got the good components. If you are building a big motor you may as well budget the right parts. As far as a First intake I can't really say but I feel the HSR is probably holding me back and I'm considering a single plane so I think the long runner intake wouldn't be a good combo for me unless I was really building for 2-3500 torque and then the heads and cam would be different. just my 2 cents.

antman89iroc

One more point from my experience. If i had realized how deep into a classic small block build i was getting into cost wise an ls swap may have been a smarter decision in the long run. Especially since you are planning a trans swap too. I really like my 414 but in the end it is a 50 year old layout and the new design is light years ahead. I know it's is Apple's and oranges but those are some damn sweet oranges.

DIGGLER

iTrader: (1)

not sure where your 414 peaks at, but if you could bump it up to around 6500 it would make some great power. i would figure 7.20's full weight in the 1/8 if you could get it to 1.50 60' on a tire.

antman89iroc

You're probably right. When I say "tuning" run, it was a soft launch with easy shifts on true street tires. Just getting fuel set and trying some things. Still running the 9 bolt rear so I was making sure not to blow it out on the first time out. I've changed to EBL computer and am looking forward to spring tuning. I believe my stock TB or Y duct may be limiting top end power as well. When I get that all sorted out it'll probably be time to look at fuel delivery as I'm running a TTA pump in tank. But in the end this is a "daily driver" so absolute numbers aren't as important as overall balance. I left a lot on the table in my build to keep it street friendly.