550hp 392...need some help

So this Is my first engine build, I don't know too much about buildin them, but I want to learn.

I've got a 58 392, its the motor I've been wanting to put in my car, and is the motor that got me really interested in learning how to make power. The engine is complete and I got it for a good price.

I know this will be an on the more expensive side to build, but it's something I'll be building over time...

I'd like this to be naturally aspirated if possible, I might be able to get a 8x2 dragstar that would like to use. Id also like to use a solid cam. And maybe somewhere around 10.1-11.1 compression.


Thanks

 

You've certainly picked one great engine! Is it an A1 casting? These tend to be stronger as they had magnesium added to the casting. I believe 10:1 compression is normal for these engines. There are quite a few Hemi guru's on this site like 73RR and scootermcrad who are able to give you ALL the info you need.

I think the size of your wallet is what eventually will determine your build. Like you've said, these are expensive engines to build but well worth it in my opinion! Good luck with the awesome build! Eric/farmer12

 

Yes it is an A1 casting. Farmer I have seen your build thread, love your car and the engine in it haha. I watched the YouTube video of it and turned the sound alllllll the way up haha

 

Thanks. I must admit to watching it too every now and then just to hear it roar! Well, the A1 casting is a good start. If it is an original virgin hemi, you'll probably need a .030 overbore. Get it sonic checked for cracks,decked etc.....to make sure everything is healthy. Then get out the numorous books and catalogs and start shopping!

 

Well, you will first need to offer a few more details of your plans.
Daily driver or just part time?
Manual trans or Torqueflight?
Do you already have a set of adjustable rockers?
What is your realistic budget?

A proper, but basic, rebuild will start at about $6k. 550 hp will likely run into the $8k range without the 'extras'.
For the 8x2 intake: manifold = $700, fresh carbs = $250-300 each and linkage is an easy $150. Total...$2850+
Adjustable rockers will add $1000.
Figure $800 for the average trans adapter package that includes a manual flywheel.
An ignition package will start at $300.

Although 550 hp is doable it will be a bit on the radical side if everything has to work with an 8x2 intake. I'm thinking that a large single carb or a 2x4 will make it easier to get to your goal.
Put a 6-71 on top and you'll have 550 easy and potential for 800-900.

.

 

Well I do have a 671 blower that needs a rebuild on my shelf..hmmm... I don't know the first thing about blowers tho...the boost..under driven.. Dont know the first thing about them

 

A1 is just the name of one of 3 Foundrys casting Hemis, all had the same specs/requirements to work with. If you haven't already, put "hemi tech index" in search & start reading.

 

The car that it will most likely end up in will e a part time driver. Haven't decided what tranny I want to run behind it yet...

 

I was fortunate to be able to watch a 354 Chrysler on the dyno in Northern Cal. The engine was a contender in the Engine Masters Challenge and ended up in third place. Made 630+ HP, naturally aspirated. Great engine. The engines in this contest are scored on being able to run well between 2500 & 6500 RPM. Perfect for a street engine

 

If you really want to build a special early hemi try and track down any of the solid roller cams that Chrysler used in there 53' Indy engine program or one of the 'Pan Am' cams no. 1535555. you can stroke or destroke the crank by welding and offset grinding or if your lucky enough to find a forged Donovan stroker crank snag it up. finding a 8x2 weiand drag star is dificult but Eelco is repoping 6x2 logs for around 350 bucks and they accept the typical 98's or holley 94's. if you scan 'hot hemi heads' classifeids everynow and then you can find some really unique/ old speed parts for sale. for heads run the 55' 331 heads more commonly refered to '555' heads or a set of 56' 354 heads, both are cast with the best port design and larger valves of all the early hemi heads. if you got the cash 'hot hemi heads' has a set of aluminum 'war heads'. 550 HP is not hard to develope with the 392, i got a friend that runs the 'Red Barron' willys and he allways has extra early hemi stuff laying around.

 

If you *really want 550 hp*, forget the 'Drag Star'
intake and 6-2bbls. Cool as hell looking and
'traditional' for a 50's-style hot rod or a '50's
vintage race car, but that's about all. Power-wise,
about the best 'off-the shelf' ie - 'non-fabricated'-
intake you can buy for an early hemi is the current
Hot Heads (www.hothemiheads.com) tunnel-ram-style
intake with either a single-4 or dual-quad top. For
something a bit more streetable in a heavy car,
Hot Heads also make an excellent single-4 'dual-plane'
intake that's capable of making good power too. Also,
check with Hot Heads too, for straight - ie - "non-old
wives tale" and "non-B.S." hemi information, advice
and parts recommendations - and for their numerous
other early-hemi 're-build' and 'hot rod, ''race engine'
and conversion parts, etc. etc. etc.(!) that you'll need
too. Besides 'Hot Heads', you might also want to join
Scott Moseman's excellent 'Hemi.Com' (www.thehemi.com)
list for more good "non-B.S." early-hemi building tips,
and knowledge

Mart3406
========================

 

i got the whole motor torn apart. im thinkin run a blower now haha.
i dont have a a set of adjustable rockers, but i heard from someone on here that someone converts non adjustables to adjustables?

im thinkin so far to punch it over .040. gonna run the 92 heads until i can afford the HH ones... since im running the blower though i dont know what cam to use.. should i leave it stock stroke with a blower?

And could someone educate me on blower boost? what the benefit is of more boost, underdriven %'s as i have no knowledge of any of that.

thanks for all the info everyone, its helping me out big time

heres a picture of me just messin around, sat the blower on top of the heads, dont have a manifold yet, im thinkin this mill will look right at home in my T coupe haha

 

and jeff i didnt realize that red pickup that was featured in rod n custom is yours, i was drooling over that truck when i was reading the article! Nice ride!

 

392s don't have the massive walls that the 331/354s have, if you're going to run a blower use minimum overbore. .040 is pushing it anyway. Get a cam ground for a blower motor.

 

ok here is my take, first if this is your first engine build, see if you can help someone else rebuild an engine first, or have someone help ya go through the process, It can help you to avoid silly newbie mistakes that can be costly to repair. that being said now onto the good stuff. power can be made cheaply but the trade off is it takes a ton longer to build. first off start with the heads, find out what can be done with the stock heads in terms of porting, and how much it will cost versus buying better flowing heads, at 550hp its going to be costly either way. remember if your going to stay in the normally asperated range the engine is going to have to wind higher to make those numbers, so once you have got the CFM out of the heads that you will need to make 550 you will also know what rpm range it will operate at, then figure for piston speed, its been a while but those figures are on the internet as well as the formula, it will tell ya if beefing up the crank / rods / pistons will be needed, or some hemi folks may be able to chime in on that, i don't know much about hemi's just engines in general. engines can be built not doing this math but i can guarantee it will cost way more in the long run if ya don't figure out the basics to make power. and most of all, have fun!

 

oh yeah, another awesome little gem.. desktop dyno! its a great computer program. as for the tranny, manual = A833 automatic = 727 i think at 550hp your going to break any other mopar trans. if it were me and money weren't an option, 4 speed

 

Lack of knowledge can cost you a grand or more easily by making mistakes that could've been prevented. Better plan your build thoroughly and don't parts until you're absolutely sure you'll need them.
Why the "550 hp"-number?
On the street, torque is what counts. HP is irrelevant.
But with a lightweight T you'll probably never have enough tire or suspension to keep it under control.

 

Exactly what I was thinking. A lot of the fellas think you can just bolt a blower on and go with it. I don't care what anyone tells you there is a science to properly building a blower motor. Too much to come up with on a moments notice or a simple post on someone's thread.

Forget about underdriven percentages what you are looking for is total boost. Pic a number, on a stockish 392, without proper pistons etc I probably wouldn't want to boost it more than 3-5 PSI on the street. Realistly I wouldn't go though that trouble. If you actually build a blower motor you can run up to 10 PSI on the street after that you run into fuel supply problems but like I said building a blower motor is way more than screwing a blower on.

You can get ahold of a company like BDS and they can give you drive pulley sizes based on the amount of boost you are after.

This whole target horsepower thing is a normal thing you hear from someone just starting out. HP is not something that can actually be measured, it is a calculation based on peak torque and rpm. Even when I am bulding a race motor I don't have a target HP I have a target RPM range and a torque number I am trying to achieve, the HP can fall where it may. Torque in a given RPM range is what wins races. Sometimes I don't even have a target torque number I just know that I have to develop torque in a given range to run in that range with a given gear set.

Here is an example. Take a 4000 LB brick of a vehicle, to hit 5,500 RPM in a quarter mile with say a 3.08 gear and a 1:1 final drive you need to make somewhere in the neighborhood of 500 lb ft. The same vehicle with say a 3.73 gear and a final drive of 1:1 can hit the mark with torque in the neighborhood of 440-450 lb ft.

None of that makes any sense does it? Like I said it isn't going to happen in a simple post on someone's thread.

You have a large learning curve, you can learn it but it probably isn't going to happen today. Ask lots of questions and read everything you can find while you are stashing money for your endevor. Its an adventure ahve a good time with it.

 

Hold on a minute. The cams you're advocating the use of are for a low deck early hemi. The original poster said he has a 392. Anyone with intimate knowledge of the early hemi knows that there are differences between the low deck 331/354 and the raised deck 392 blocks. They have a couple degrees different lifter bore angles to maintain decent pushrod angles. You CAN interchange low deck and high deck early hemi cams, and the engines will run, but you will definitely not be getting all the performance that you would with the proper camshaft.

 

'T' coupe...?? you'll never get it to hook up with a stock 392.

•Absolutely nothing wrong with the 392 head, especially in a blower package. Its pressurized, remember? And you already own them...
• A blower 'package' will be in similar $$ territory as the 8x2 but you will still need one or two carbs.
•Use a hydraulic cam, new or regrind. Less maintenance, less initial cost.
•The less boost you use the less stress on all of the internal parts. You will still need custom pistons and you really should use a beefier rod.
•Sonic check the cylinder walls and keep the overbore to a minimum.

Settle on a build plan before you start buying any parts and then stick to it. Unless you just won the Lotto you probably don't need a bunch of expensive Hemi parts that you can't use.

.

 

OK Here's my question on the 392 Hemi...How would you rate the 392 Hemi to a 1970 455 Buick GSX motor, considering torque, horsepower etc? I want to go all Mopar, but I already own the 455. The 455 was notorious for blowing away the Hemis back in the '70s. Any thougths?

 

I have a thought.
Seems like you're hi-jacking the OP's thread.

 

Probably the 426 Hemi & supposedly they were difficult to keep tuned with the points dizzy in use @ the time.

 

Not much to add here except I agree with the above!

A LOT of money can be spent on an early Hemi and the RIGHT money can be spent on the RIGHT parts to get a really nice boost in performance. Do your research. Plenty of info here and in books.

I'm also curious why you have mentioned certain numbers for this engine. Maybe I missed it but I didn't see what you were building and to what era. I saw the part about it being somewhat of a part-time driver, but you didn't see where you said what the vehicle is.

It's already been said that era correct parts will get you a certain look by all means, and there are plenty of new parts out there that will give some awesome performance but maybe not fall in the "traditional" aspect. So I guess it just kind of depends on what you're after.

Personally, I just like late 50's early 60's era drag cars, so naturally the early speed equipment is appealing (Drag Star 8x2 or 6-71 with a bunch of 97's on top). But if I were building something that I was planning on taking to the track and wanting to really get down to business, I would look at putting money in some more up-to-date speed equipment.

It all comes down to how deep your wallet is and what you're ultimately looking for in looks and performance. If you're just scooting around town and want to advertise the "size of your package" you've picked the right engine no matter what you do to it.

OH! And two words... "THREE PEDALS"

Good luck with the build! Keep us posted!

 

hold on and dont jump the gun. you can run the early factory solid roller cams in the 392's with no problems and they were just a suggestion if they were available.

 

SixFour
check out 'hot hemi heads' out here in NC, they got everything you need to build up a 392 with the power requirement you want. the blower will definetly get you there faster!

 

The general consensus is you can only run 392 cams in 392s & get it to run right. However one guy claimed to have compared NOS 354 & 392 cams, using measuring equipment I assume, & claims there is no diffrence between the 2 cams. considering that new cams for the 392 are redily available, why take the chance.

 

Their is a differance between a 331/354 and a 392 cam because of the deck height.Also these motors are torquers not big HP.Dont get the wrong impression,i love em and have a couple,but they are a little over rated in the performance.I have a very nicely buildt 354 and it chassis dynoed at a little over 300 hp at the flywheel,but the torque was like 360 ft/lb.Getting 500 hp out of a naturally aspirated early hemi someone would have a ton of money in.A blower motor will make somewhere around 500 with out much trouble.My 2 cents.

 

there is no difference in either. you can run the cams in both blocks, it just depends on what type of lobe profile you want. the only difference is the extended snout on the 51-53 early cams that take the retainer plate. the deck height is higher on the 392 but that only affects the timing chain length (you need a longer chain). the relative location of cam lobes to lifter bores are in the same position on both motors, the journals are the same dia, the lifter angles vary slightly but do not affect the cam lobe to lifter alignment.

my advice, pick up one of the cam profiles that hot heads sells, or try schnider, or isky. you'll be happy with the grinds, and its a lot easier than tracking down old race pieces and having them reground.

its what you prefer not what any of us think,.....potato...patato.....tomato.....tamato