I have heard of people claiming to make 450 hp/tq easily with motors out of late 80's Suburbans. Those motors only made like 230 hp and 330 tq. My present sbc mild combo makes more than that. How is it possible to make over 200 hp and tq with a cam, intake and exhaust????. Am I missing something here?. I would seriously consider this swap if feasable but I find it hard to believe. Any info would be appreciated.

It's still a 454. It might not be tuned for much power, but it has the capability.

The best way to do it is to raise the compression, but just installing a cam that produces power at a higher level will help. Stock redline is about 4,000 rpm. Help it breathe and cam it to do something and it will be a whole 'nother animal.

First off, GM rates their engines--including their crate performance engines--using the full SAE specs for net horsepower.

I don't know of ANY "aftermarket" dyno shop that does that. So, at best, you're comparing "real" SAE Net horsepower ratings to "inflated" (I could also use the word "bogus") dyno-shop HP ratings. At worst, you're comparing SAE Net ratings to someone's WAG rating. (That'd be "Wild-Ass Guess".)

That sort of takes the mystery out of why GM crate engines always make more than their rated horsepower/torque in the magazines. In part, it's because the magazine's dyno shop is not using the full SAE protocol.

Second, the GM specs for those old 454s is at a very low engine speed. So, sure, you can make more peak power with a small block...but you're gonna need at least another thousand RPM (and probably more) to do it.

Also consider many GM engines are underrated, just because Chevy said it was 230 hp and 330 ft/lb, doesn't mean it really wasn't say (for example) 280 HP and 400 ft/lbs from the get go or whatnot.

And really the biggest problems on those older truck motors is a restrictive exhaust and intake/heads. Bolt on headers and dual exhaust, slap on a nice intake, and bam you have a instant large power boost. Stick in a cam or better heads and you have a pretty hot motor without really working too hard in making it that way.

that 230hp rating is with all the smog crap hanging on the motor, computer tuning for low emissions/high MPG, through 2 1/2" cat and full exhaust. And rated at the rear wheels. In comparison. The LS6, rated 450 (act. 500+) was rated at flywheel with no acc. and a free flowing exhaust

The biggest secret to making the power is you deciding on what you want and when you want it.I personally started out with small blocks a lot of years ago,and just could not get what I wanted.A friend let me use his SS 396 for a while and I found what I wanted.Now everything I own is Big Block powered.Off idle torque,and at 80mph, tap the loud pedal and the nose of the cars lift.The other plus for me is just opening the hood and looking at what is staring back at me.Big Iron!! Don't get me wrong,I still love them all.

Thanks for all the responses. What would a bone stock motor like this typically sell for that was in running condition?.

As far as selling prices go....a big part is where your at. I can say that round here......a good running but used, and stock 454 thats ready to go could definitely get 1200 bones. Prime year motors can go for more. Freshly rebuilt bone stockers can grab 2 grand(or more if its a desireable prime year motor). At the same time.....if you hang out and be patient, you occasionally stumble across a real good running one for say 850 that could be used as is and even survive with bolt on goodies and some thrashing. That aint as common though. If you find one round here much cheaper, its definitely in need of a rebuild even though it may still be running(running well enough to get the job done....but nothin to write home about). That might be chump change for a big block where your at...then again, it might be kinda pricey too.

For a late 80's bone stock motor with some miles and a need for a freshening....Id be expecting an average asking price somewhere between 650-850 but once again....it could be a lil more or less depending. If you can hear it run(even if it dont run good) that often drives the price up more to the 850 range for the average smogger big block. Hope that helps, but its a tough call. Look around the papers and call the wrecking yards to get an idea of what youd typically pay in your area.

Thanks Greg. I know where one is that I can hear run for $1000 that is still in the Burb and supposedly runs good.

First off, GM rates their engines--including their crate performance engines--using the full SAE specs for net horsepower.

I don't know of ANY "aftermarket" dyno shop that does that. So, at best, you're comparing "real" SAE Net horsepower ratings to "inflated" (I could also use the word "bogus") dyno-shop HP ratings. At worst, you're comparing SAE Net ratings to someone's WAG rating. (That'd be "Wild-Ass Guess".)

That sort of takes the mystery out of why GM crate engines always make more than their rated horsepower/torque in the magazines. In part, it's because the magazine's dyno shop is not using the full SAE protocol.

Second, the GM specs for those old 454s is at a very low engine speed. So, sure, you can make more peak power with a small block...but you're gonna need at least another thousand RPM (and probably more) to do it.
=
Hey,,, I represent that :D
Bogus numbers just because we use a different standard?
If almost all performance shops use the STD standard how does it become bogus?
Do you have any idea of the difference in the two standards?
You make it sound like a friggin zillion HP :(
There are a ton of bogus numbers out there but it has nothing to do with the standard, it has to do with people posting crap numbers to sell stuff & in some cases magazines.

Here are some "bogus" numbers for you to ponder & I do use the STD correction.
I call these my reality check engines for a few of the "interesting numbers" we all know & love that are what I feel are truly "bogus"

GM 502 "off road" hyd roller engine
Advertised as 450HP, 550 lb ft.
On my dyno 472HP, 560 lb ft

GM 454HO hyd roller
Again, advertised as 425HP, 500 lb ft.
On my dyno this was 450HP & 522lb ft

GM ZZ383 Crate
Advertised 425HP, 460lb ft
On my dyno 434HP, 452 lb ft
=
And the answer to the difference in correction factors is about 5%
This makes a 500HP engine STD about 475 SAE
STD: 60 degreee air, 29.92, altitude 0
SAE: 77 deg air, 29.60, altitude 0

that 230hp rating is with all the smog crap hanging on the motor, computer tuning for low emissions/high MPG, through 2 1/2" cat and full exhaust. And rated at the rear wheels. In comparison. The LS6, rated 450 (act. 500+) was rated at flywheel with no acc. and a free flowing exhaust
=
Not so, GM does not rate their engines at the rear wheels.
They do rate the engines supplied in vehicles as SAE net flywheel with all accys though., have since the mid 70's
Crate engines are not rated as net with accys, they are SAE std.

It would be nice if everybody rated horsepower the same but the manufacturers and the aftermarket generally have different agendas. That SAE spec of J1349 changed in the early nineties. The old rating was taken at the more optomistic 0' air at sea level, (59 degree, 29.92 barometer and zero humidity) since they started recording numbers then someone decided to decrease the horsepower ratings to represent more average air numbers and changed the J1349 spec to (77 degrees, 29.32 barometer and zero humidity) which represents 1000' air. According to a local engine builder, if you want dead accurate readings you have to calibrate an engine dyno (SF901-902, etc.) before the pull or know what the error in your particular dyno generally runs and correct your results to match. Any "Dynojet" rear wheel chassis dyno has a completely different set of parameters as does the "Mustang" chassis dyno which differ from each other and include driveline losses. All manufacturer's H.P. ratings are "SAE net" this side of the mid seventies.

This is a subject that will always raise the hair on the back of your neck.An old friend of mine has always said: to Heck with your Hollywood Romance dyno numbers,line that thing up beside me and we will see what the numbers say.After all,that is what its all about.Call it old fashioned,but oh how we love it,.

Mike, the comparison of the two HO motors is very good. I have used the data you posted before to calibrate my DD2000 sim program (what I did was play with the advertised duration and the air flow file to get the results to mtch what you have posted. Have settled in on advertised dur. at 60* over .050 and air flow data set 28". Margin of error doing it this way is about 5%. Which quite frankly I think is pretty darn good).

Getting back to the HO motors as an example, a 22HP and 32 FTLB torque gain is what I woud expect to see from a 48CI increase given the same stroke. Good info here.

These engines were actually 230 hp and 385 lb ft, not 330lb ft. And in, I think, 91, a version came out in the SS 454 trucks with 255 hp and 405 lb ft. So 450 lb ft isnt that much of a stretch. I guess I am assuming you are speaking of the TBI Motors that came out in 87.

NBK- I only did a search for an 87' just to see what the specs were because that's what the guy is selling. My original plan was to just buy a set of aftermarket heads and be done but am now considering the big block swap. Still haven't decided yet. It's just a cruiser but I want maximum fun factor without breaking the bank!

if you have a 4 spd
beware
there is nowhere to put the z-bar stud
you would need to use an alternative for the clutch setup
I have two of these motors sitting here and can't use either one
both my chevelles are 4 spd cars and I don't want to convert to a hydraulic clutch
luckily I have a 454 from 73 that is in the ss
but I would really have liked to stick a BB in the vert

SD sell's a bolt-on bracket to install the clutch block ball stud to..

Like $50/each?? I figure it's a steal when you think about hand making one and not having a shop...

pdq67

Thanks for the info guys, but this would be going in my truck with a 350 turbo trans.

if you have a 4 spd
beware
there is nowhere to put the z-bar stud
you would need to use an alternative for the clutch setup
I have two of these motors sitting here and can't use either one
both my chevelles are 4 spd cars and I don't want to convert to a hydraulic clutch
luckily I have a 454 from 73 that is in the ss
but I would really have liked to stick a BB in the vert

Does the Z bar bolt to the motor or the bellhousing??
If it bolts to the bellhousing, will a pass bellhousing fit over the 454 flywheel??

Does the Z bar bolt to the motor or the bellhousing??
If it bolts to the bellhousing, will a pass bellhousing fit over the 454 flywheel??I have four 621 bellhousings that will fit over the flywheel
but the z-bar stud mounts to the block on the 64 - 72 chevelles
not sure of the later ones though

Fwiw, my '67 First Gen Camaro's B/H has an untapped hole in it and my SB block had two tapped holes which created three locations to install a Z-Bar ball-stud.

pdq67

Just want to be clear here :confused:

Are you saying the later BBs don't have anyplace to mount the Z bar for the clutch??

"SD sell's a bolt-on bracket to install the clutch block ball stud to..
Like $50/each?? I figure it's a steal when you think about hand making one and not having a shop...
pdq67"

If not, could you let us know where to get one of these? SD?

yeah I'd like to know where to find one of those brackets
it seems a waste to let these two 454's sit just cause I can't hook up the clutch linkage
it would be nice to put one of those in my vert
even though the motor in there will have plenty of guts
it still would be nice to jam the big block in there just for *****s and grins

SD = Scoggin-Dickey http://www.sdpc2000.com/

Here it is, next question is my BB is a 86 how do I tell if one is required or not?? Says for Gen V & VI, I am under the understanding my block is a Gen IV, but the donor vehicle had a hydrolic clutch. :confused:


SDPC Clutch Pivot Ball Brackets
Vistit our Scoggin Dickey Parts Center store
Z-Bar Pivot for 502

The SDPC Exclusive Clutch pivot ball brackets are for use on Generation V & VI blocks. These pivot brackets provide proper mounting position and alignment of your Z-bar on all GM cars and pick-ups. The super strong brackets can handle the high pressures of racing clutches. A longer bracket is available for use on corvettes. Pivot ball is included.

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SDCB Clutch Pivot Ball Bracket for GM Cars and Trucks $59.95 Add to Order
SDCBV Clutch Pivot Ball Bracket for Corvettes $59.95 Add to Order

thanks

Just a note on the power topic of this post. I had the head off of an '87 fuel injected 454 in a one ton crew cab at work (broken exhaust manifold bolts) and it had really low compression pistons. In the shop manual if I remember it was 7.3 to 1. I think a raise in compression ratio would be one of the first things that should be done to bring a late model '54 to life.

those tiny ports on the heads are also power thiefs
a nice set of heads will probably help as well

My '75 454 P/U motor had -781's and true flat-top pistons in it so I figure it was down around 7.9 to 8 to 1 or so! (Supposed to be like 8.5 to 1!!)...

Yes, first thing, get the CR. up to around 9.5 to 1 so that you can at least run a 270 cam in it OR leave it alone and run something like a good old CC 260HE for towing grunt.

pdq67

with the compression that low
what about slapping a blower on it
on the other hand
by the time you make the lower end strong enough to handle the blower
you might as well just rebuild the motor to your own tastes

My 86 motor has flat-tops That measured exactely 16 thou beloe the deck.
The peanut heads really have a deep dish compared to the 290 heads I plan to use.

My 86 motor has flat-tops That measured exactely 16 thou beloe the deck.
The peanut heads really have a deep dish compared to the 290 heads I plan to use. My son has a '83 motor with the older 781 open chamber oval port heads in a three 3/4 ton Suburban with extra compression (about 10.5) which weighes 5500 lbs. and has a 268 Comp cam. This is a very good combination but kinda pricey to drive to work.