I thought I'd post some results and let all of you draw your own conclusions.

In the last 6 months I've done a few different builds, 2 of which were an iron headed .040 over 455 Olds as well as an aluminum headed .030 over 454 Chevy. Same dyno, same conditions.

Now I know there are differences in the 2 designs with the BBC having a larger bore and slightly shorter stroke. In addition the BBC has a wedge shaped combustion chamber and splayed valve arrangement. But as you'll see there are a lot of similarities in these two builds as well, and the difference in hp/tq is significant.

Here are the specs on both;

455 Olds
Ga heads, 2.07/1.68 valves, no major work
Hyd Roller, 231/234@.050 on a 111, in at 107, .565 lift with 1.6 rockers
Performer RPM Air Gap, center divider cut 3/4", otherwise stock
850 Quick Fuel DP
10.0:1
1 3/4 Flowtech headers.
413hp@4900rpm, 496lbft of torque at approx. 4000rpm

454 BBC
Edelbrock Oval port E street 110cc heads, out of the box
Hyd Roller, 231/239@.050 on a 112, in at 109. .647 lift with 1.75 rockers
Oval port Performer RPM Air Gap, out of the box
850 Quick Fuel DP
10.0:1
1 7/8 Hooker Headers
520hp@5600rpm, 542lbft@4100rpm

Pulls started at 3400, again same dyno, same conditions, same fuel from the same station, same machine shop did all machining on both. Both were tuned for max results. At no point did the Olds make 500lbft of torque. The BBC made 500+from 3400 to 5200.

My point? Why anyone would fool with stock iron heads on an Olds is beyond me, especially with the advent of the Procomps. No I'm not a dealer for them, just a very interested by-stander.
Another point, the 434DX I did made 471/497, same cam as the BBC except on a 108 with a bit less lift. It had 10.25:1, an 830 with a slightly massaged Victor with the same Flowtech headers as the BBO. The difference? Out of the box Edelbrock heads, and there was more to be had on that build.

Feel free to form your own opinion. I have mine.

 

Point taken and understood. If I wanted a Chevy in my Olds I would have put one in. A 502 from the factory was available. I like the Olds in an Olds concept. Super Sport Chevelles are a dime a dozen, not to mention Camaros. Maybe a dare to be different if a little slower? Cost sure isn't the reason. Your argument taken to its extreme would mean everyone who needed their Olds rebuilt would put in an LSX.
When the hood goes up and it's a nicely detailed Olds motor in a 442 or whatever Olds car you pick, it is like a trip back in time when everything wasn't cookie cutter efficient. Just my .02.

 

I think you missed my point. I'm an Olds guy thru and thru.
But I'm also a realist and don't waste money on stock iron BBO heads. I see no reason too.

 

How much more hp/tq would have been gained if the Olds had the same lift 647 vs 565 and 1.7 vs 1.6 and the bigger 1 7/8 hookers..Plus the bbc valves are bigger, just use Eddy heads on the BBO build and the difference would be what.And thanks for posting your results...I see on another forum where a builder got some nice #'s 500/600 on a build similar to mine and I was surprised because he got those #'s using a small carb and a performer manifold,and ootb eddy's,with a street friendly cam.

 

Mark, would it be possible to post cost of each of those builds? Are they close? Is the Chevy cheaper, even with aluminum heads? I agree, why use iron heads if the gain in aluminum is that much greater....

 

I'm going to use stock iron heads on my motor build. WHY? Thats what I want. it don't matter what other people think of the motor, as long as I'm happy with it, that's all that matters to me. I didn't want aftermarket heads, intake carb on it. That motor is going to look stock appearance, except for headers, fuel pump,balancer, and oil pan. It's going to look like a regular 455, BUT inside is going to be a little monster pushing around 500 HP 540 TQ. Possible? YES--Foolish? MAYBEE--1970 W30 "F" heads? ABSURB--Overbudget? WAY OVER BUDGET--Ridcolous--PROBABLY. Expense--VERY EXPENSE. The smile it will put on my face-- "PRICELESS" . In my opinion, it depends what the customer/car owner can afford and what they want.

 

Some people want a stock all original motor, that would be one reason to stay with the stock heads. Plus even I can figure out that the engine with the bigger cam, bigger headers and aftermarket heads will produce better numbers than the other.

 

I agree on the aluminum heads for an Olds, however the comparison is not apples to apples on your dyno test. I bet even with iron heads your BBC will show better numbers.

 

We all have our reasons to do what we do. I like both the Olds and BBC options and the only reason I bought a 454 was to go fast at the strip for cheap. Trying for mid 11's at 3600 lbs (pump gas). For the street I would stick with my stock 350 SBO(still in the car), but again we all have different reasons for doing what we are doing.

I did look heavily at both the 455 and 454 when comparing apples to apples. I wanted an easy without trying 425-450 hp with a stock bottom and stock top end, while just adding a carb, headers, intake and cam. A factory 455 with 8:1 wasn't going to give me that for the price of a stock 454. Plus good flowing BBC oval port heads are a dime a dozen (fresh enough) and for nearly free wherever you look. It was hard to beat my 454 for $650 ready to run with a holley DP, performer intake, Comp roller rockers and 781 big oval port heads already machined with bronze valve guides and aftermarket valve springs.

Olds or Chevy and just have fun with your choice.

 

Mark,

As I started to read your post, I was wondering why you were bothering to compare an Olds with stock heads and a Chebby with aftermarket heads, but then I got to the punchline. Couldn't agree more. In terms of return on investment, all shortblocks are about the same. The easiest way to make HP is in the heads. Yeah, I'll use stock heads on the H/O and W-30s because I have to, but the other cars definitely get aftermarket.

I just wish someone would build a set of aluminum Olds heads using chambers and ports based on the LS designs. This is where modern technology has paid off in terms of design.

 

The extra lift and header difference isn't worth any where near the 100hp. Especially if you don't have the heads to take advantage of the added lift.
And I saw that build, it's from CJ at Mondello. I questioned it, I don't believe the tq number for a minute. hp maybe, tq? No way.

Forget the BBC to BBO comparison. At the very least the DX vs the BBO would be a good example as well. Similar build, compression, head design, same headers, smaller carb etc. The Edelbrocks still smoked the irons, plain and simple.

Both builds were in the 7K range. The Olds had too much money in the heads but we were half way there and couldn't turn back.

 

You got it Joe. I knew you'd get my point.


And Brads' heads are exactly that, a SBC design, actually more of the SB2 format but very modern nonetheless.

 

For performance Aluminum heads give you more and easier growth potential.I got them on my 455,could have used my C heads but didn't. Also like the benefits of a roller cam and rockers. Always appreciate your efforts,it's how I learn...kept the threads coming.CJ's build is very close to mine.I spent a tad more than 7g's.but wanted to keep my 442 Olds powered! No regrets! CJ's build has me thinking I saved money not getting the torker and bigger carb.

 

"My point? Why anyone would fool with stock iron heads on an Olds is beyond me, especially with the advent of the Procomps. No I'm not a dealer for them, just a very interested by-stander."

Simple, depends on what you are building and why. You want to go fast use the parts that get you fast. You want all original use original. Return on investment? Try selling all original vs a pieced together and get back to me on that.

 

Perhaps to drive the point home even better would have been to build a 455 short block, dyno it with iron heads then dyno it with aftermarket heads and see the contrasts. The title bbo-vs-bbc has immediately raised the ire of some and they can't see past it to understand or appreciate your point.

 

I believe this is a thread about going faster with iron or aluminum heads.The design of the Edelbrock or Procomps will let them perform as good or better than Iron heads even after spending many dollars on the Irons. At least you hope.Then you can spend some money on the aluminums,and better valve train and hang on. It's all good.Personally I wish I had the money to keep the stock appearance and run 10's.

 

This place is getting as bad as ROP.

Whatever. For those it applies to, I won't post anything next time. You all can bench race till the cows come home.

 

Bench racing.....haven't heard that in a while. And DON'T STOP POSTING!! Your input hear is very informative and helpful,and free. And a little bench racing never hurts.

 

It certainly doesn't surprise me. All my rebuilds have been stock rebuilds with better internals. One day I'd like to have the opportunity to go modified but not sure what that would be. I appreciate the post and the information, keep it coming.

 

The one good thing is that the 455 mentioned with the iron heads at the beginning should easily put you in the 11:70 - 11:80s at 3600 lbs, which is plenty fast for the street/strip vehicle. 413hp is a good motor by my book and with iron heads.

Below is a great blog of someone only pushing 425 hp from a street pump (8.75 to 1 compression) gas motor in a 3300 lb car. Disregard the brand. I'm not pushing the blog from the other website, but it shows you what tinkering with something can do. A 455 with iron heads should easily be able to perform in this manner, but the cost may be a bit more.

If you read the blog, really pay attention to the trans gearing and not the rear gearing noted in the article. With the correct height tire you can easily run the rear gear on the street to local cruises.

http://drr.infopop.cc/eve/forums/a/t...2/m/4947098526


Do we really need 500 plus hp for the street?

 

If anyone wants to stay all original and give away a pair of aluminum heads i'm always willing to give them a nice home

not sure if they'd fit on my 350 though..

I thought both 350 and 455 used the same head gasket, so in my mind wouldn't they should fit.

 

You can run BBO (including alum heads made for BBO) on an SBO. You'll have interference with the mechanical fuel pump, though. There are ways around this. Beware that the combustion chamber on alum heads is BBO sized, not SBO sized. This means something to your compression ratio, of course.

CutlassEFI: I for one appreciate these threads. It's understandable that many guys want to stick to factory heads for various reasons, but that doesn't mean info like this isn't nice to have.

Joe Padavano: Would a head design with LS-like features like the one you described not need a different valvetrain design, including pushrods and so forth? If the valves don't sit at the same angle as on Olds heads, innovations to the rocker ratio and other such things would have to be made, I assume.

 

500hp in the city is more about bragging rights, unless your street racing for money.In that case you don't let anyone know what your car has! 413 hp @ the cranck in a 3600 lb car gets you in the 11's? Cars with 475hp are still in the 12's.Heck I hope your right,my car should be there than.

 

IMO, it isn't a matter of "faster", the aluminum heads are better, for the same or less cost. That is the issue. Take iron heads, put in new guides, valves, a decent valve job, minor port work (if you can even get a shop to do it anymore), surface clean up and you are pretty close to the Pro Comps which are lighter, have a better chamber, flow better, no crossover, and have the dividers. Other than "stock appearing", there really is no fiscal reason to rebuild 40-50 year old iron heads. IMHO.

 

Any Olds vs Chevy/Buick/Pontiac/Caddy/ Mopar/Ford thread is going to upset a few on this forum.
The OP was simply pointing out the difference between two on the surface similar engines. Given his expertise we have no reason to doubt the figures.
All engines have their pros and cons, whether it's a big block or a lawn mower motor.
However Chevrolet have a lead over most other ohv V8s simply because there are so many out there and there is a vast infrastructure for getting more power out of them. And it was a good engine from the start, if it wasn't it wouldn't have stood the test of time so well. I don't fly a flag for Chevrolet, but credit where it's due.

If you go to a Pontiac or Buick forum (or Ford or Mopar) you will find plenty of threads extolling the virtues of their particular engine(s).

I prefer to see an original engine under the hood of any classic, if it's an old car it might well be a flathead. But I won't hold it against anyone who has put another engine in their car. It could be for any number of reasons, reliability could be one, availability could be another, certainly it happens over here - I've seen Chevy engines in Fords, Ford engines in Chevys, even an AMC engine in a Plymouth Fury!. In most cases it was because the original engine had failed and they used what was to hand, necessity being the mother of invention. In Cuba there are plenty of Lada powered old American cars because that was all that was available to the Cubans.

Roger.

 

Thanks, Mark!

- Eric

 

We have a winner! Its hard to argue with the facts. Unless your building a Hurst/Olds, W-30 442 or other high dollar car the factory stuff isn't worth sinking the money in.

 

Aluminum heads for me is about making more hp/tq.My 400g motor had 190000 original mls and I was making passes 14.70@93mph using racing fuel,also the car had headers and 373 gears.It still remains to be seen how many miles I'll get on this 455 iron block motor with the Procomps before something about the heads needs my attention. So as far as longevity goes,not sure if there gonna be better.Everything else about them is better.

 

Let's cut to the chase here. I don't dispute his expertise or his test numbers. I don't dispute that modern aftermarket heads are better and more cost effective than decades old iron heads. That's not exactly how it was presented though. You label it Olds vs Chevy on an Olds forum, you make an apples to oranges comparison, then end by basically saying why would anyone do other than you would do. Sometimes its not what you say but how you say it.

 

Mark, what I was leading to was a "heads up" test of the same set up on the Olds with aluminum vs iron heads. That would be an interesting comparison. I guess I was not really clear after rereading my post.

 

I have to admit that I still don't see the relevance of the comparison...
But, I would LOVE to see a side by side with both motors having a set of Ebrocks or Pro Comps.

 

I understand some of the comments, some I don't.
I'm doing these dyno sessions with different combinations with the blessing of the owners, and sometimes the cost for the additional time is out my own pocket. If any of you that posted less than stellar feedback want to do this then have at it. Dyno all the combos you want, but you'll have to pay for it.

As mentioned, if you want to then disregard the BBC reference and just compare the DX build with the iron headed 455. Similar carbs, same headers, same dyno on the same day, cam difference was only 3 degrees and .030 lift. But with 29 less cubic inches it made the same torque and 58 more Hp than the iron headed 455. Take it for what it's worth.

 

Aluminum vs Iron..Eddy's vs Procomp. Seems like Cutlassefi is one guy that would and has shared his hard work and results.....sometimes it takes a minute for a guy like myself to get it.Think how I feel I have to live with me. Seriously we say things and we know what we mean but the way it comes out confuses other.And were not all as knowledgeable as some.Don't get pissed just realize that.

 

Thank you.

 

mondello shortblock 3800 dollars plus 6600 rpms tops. edelbrock heads 1600 dollars. I look for sales also. I make more power then that chevy engine also for less period. I also have seen a decent 455 olds 10 to 1 compression and a 18-20 mondello cam do 350 rear wheel power on a chassis dyno plus 12.80 quarters with a 3.08 gear.

 

No Mark..Thank You,If anyone here doesn't get you,then their in the wrong hobby.In the long run,anyone that knows will get it.

 

After having read through the posts a few times it seems clear to me that aluminium heads are better than iron for hp. I think we all know that but thank you for putting up some figures.
Some of us don't like the idea of a non Olds engine in an Oldsmobile, well we live in the (relatively) free world so get over it.
Clearly both engines were built for power, question; how much hp per dollar are you getting?.
Thought; if I were to build an aluminium headed engine (it doesn't matter which maker it comes from) to make the same power as an iron headed version how would costs compare?. Assuming the iron head would need a higher state of tune what about durability?.
I'm guessing the engines you built are for the strip or track, are there worthwhile gains for an engine that would be happy in traffic using aluminium heads, milder cam, less carburettor etc?.

Meandering from the topic, my thought train is because my all aluminium dohc 4 valves per cylinder computer controlled fuel injection Nissan makes 53hp from 1 liter on our crummy UK gas, yet is smooth at low revs, keeps up with traffic and returns great gas mileage. Also with proper maintenance it should be good for 200k miles. Admittedly the whole car probably weighs about the same as a big block and transmission.
To get that kind of power from a similar sized iron engine would mean making it a nightmare in traffic and gas mileage would be horrible, and it would probably cost as much if not more to make in commercial quantities as well.

Roger.

 

thanks Mark, your posts are always interesting! I am glad you do these comparisons on the same dyno at realistic temps... it takes out so many of the variables. I realize all it takes is money and time... lots of both!

Once again, thank you! and PLEASE keep posting!

 

I just completed having my 455 built by a very good shop. I so wish I had the money to dyno it but I was WAY over budget. I uses iron (Ga) heads that I got for free. They had some work done to them already, but I still put another $600 into then. So I can't justify the cost for a set of aluminums. In a couple years (after the sting of the initial build wears off) I would like to change the heads with aluminum. It would have been nice to see the dyno with irons and aluminums then. Maybe I can have it dynod before and after I swap the heads at that time. Sure, maybe in a perfect world!

 

dfire25 your car/engine look awesome good luck with it. As for power #'s you can look for combos here or on the other Olds forums and compare specs.Gives ya an idea where your at. It's another reason why builders posting accurate results helps...plus it's cheaper and easier on a motor not built for the track.