Steps for a big power olds motor

[81cutlass]

I happened on a stack of Olds parts I could pick up. Kinda would like to do a 9.99 sec olds powered street car setup in my Cutlass in a few years. Likely EFI and turboed, 4l80e. 9.99's with AC, daily driveable. Basically just need to know whats worth buying for the build and what is better purchased new or elsewhere. Just be nice to have a quick street car that doesnt have an chev motor under the hood. Not that im a purist but doing things the hard way is kinda rewarding in the end. If its a BOP it should have a BOP unless you just want to go fast in a ratty race car or are broke. Not that budget is not a concern, it wont be cheap, but its a long term project.

Basically, I have access to

Rebuilt 455 C heads
455 Nodular iron crank
455 Block
-(looked at this stuff, its all real good, just kinda pricey)

425 Forged crank and rods
DX 350 block
1 C and 1 B head cores
425 block
403 heads
crappy smog SBO heads
-(havnt looked at this stuff, dont know the condition but its cheap)

So for a 600-700ish hp turboed olds, where does the DX block come into play for extra strength over just putting a 425 crank in a BB? Im kinda building the motor around the forged crank, may not be a great idea. I have no idea what shape the crank is in. Ultimately i was thinking 425 clearanced crank in a DX block with C heads based on just the parts I have available. The remanned C heads are nice but they are still an iron head and at ~$400 its not really tempting when alums are $1200 and, well aluminum. Does a iron C head even support 9 second power? Are forged pistons available for a 350 block with 425 compression height as an interchage or just bore out the DX block?

I dont plan on getting anything put together for a few years but its not all that common to find all the stuff I need basically.

Any other places that have good advice? Theres like 4 other olds specific sites but ive heard its a PITA to register for some of them.

 

[Blake442]

The 455 block should handle 600-700 horse. Beyond that you might want to consider the DX block.
DoubleV on the board here just put together a 350 DX with a 425 crank and C heads to the tune of 440 c.i.
He's not at the power levels you're looking for but might be a good person to hit with some questions.

As far as aluminum heads go, out of the box they flow about the same as factory C heads.
The weight savings is a big draw, but either can be ported for big power. There are sub-10 sec. cars running C heads...

Read around on realoldspower.com... Lots of good info and builds.

 

[dogsht]

As you try to go quicker eventually everything starts to come into play. Things get more involved and take more time and MORE money for smaller and harder fought gains. Oh yea and its not just for gains its for fixing and replaceing what you are going to break getting there and making it reliable. What is the fastest thing you have built and or at least driven down the track so far? And your definition of streetable would be?

Doing things the hard way is rewarding.. mmm yea just watch what you wish for lol. Affordable reliable daily driveable pump gas overdrive efi AC & 9.99s don't go together well. Oh and old Olds 455s & turbos. Even with some experience with turbos fabricating some shop & welding experience etc as you have.. its a tall order. Just saying. The combination of both of my cars which you can read about in my signature and see in my photo album are both along the lines of what you are talking about only with more modest or reasonably affordable attainable goals of mid to high 11s in the 112 to 115mph range. Beyond this ET/mph range it gets a lot more difficult and expensive when its not a race car. Just going from 5 to 6 to 700 HP reliably with an Olds 455 even with a power adder becomes a lot more expensive and involved and that's just the motor. An honest 500HP big block gbody on the street is already ridiculous fun shortly thereafter it often slips into and expensive frustrating overkill PIA. fwiw cheers

 

[jetsetw31]

Basically, I have access to

Rebuilt 455 C heads
455 Nodular iron crank
455 Block
-(looked at this stuff, its all real good, just kinda pricey)

425 Forged crank and rods
DX 350 block
1 C and 1 B head cores
425 block
403 heads
crappy smog SBO heads

Of the available parts you have listed, It is possible to build a high 9. sec car without the turbos. But it won't be too streetable.
Option one.
The combo that I know will do that is the 455 block and heads and the 425 crank and pistons with a compression of 11:1 or better. Basically making a very strong 425. I've seen these motors run that number! The 425's ability to rev high is what makes it a great race motor. It's actually similar to the way the chevy 454 makes power. Enough bottom-end torque to get you moving and enough high- end HP to run a 9.

Option 2.
In contrast, the 455 is a high torque motor that has issues spinning past 5500 in stock form. With REALLY GOOD machining and head work, it can get to 7000 and up. But not really reliable at making consistent high power with out breaking something. Really pricey to get a 455 to make that kind of race motor even with turbos. Too much torque will find parts to break.

Option 3.
The DX block is great for making a mean big inch small block and a killer small block race motor. So many ways to build this block, I can't list them all.

As for your goal of a 9 sec streetable motor, I'd use the 425 combo with about 8.51 -9:1 compression with turbos and boost control for the most reliable way to obtain that goal. It won't be cheap, but it can be done.
Just my honest opinion.
T
The Olds guys you want to talk to are BTR and DMR. (Bill Trovato and Dick Miller)

 

[81cutlass]

I am leaning towards the DX block 425 crank aluminum heads. The 455 block 425 is super close but ive had a tall deck olds motor in a G body and I made sure to look and it would be tough to get headers to a turbo and down pipe out the back of the car. 425 is easiest but im right on the edge of what I feel comfortable a 455 block will take.

Streetable to me is being able to start it when its 40 degrees out, put 500 miles on it and drive home. Ive personally ran 13's in my winter beater firebird. Ive riden in a decently serious 11 sec car. Should have a 9 sec race G body that I will be able to put some passes on within 2 years so thats before this project will get done.

My thought when I looked at the C heads is I could get a 425 long block built for $1500 with 400 hp in a mild setup just carbed NA for a little while since the only thing I needed was bearings, gaskets, and pistons but the cost of the C heads kinda hurt that.

 

[jetsetw31]

it would be tough to get headers to a turbo and down pipe out the back of the car.

Good point, Gbodies are tight around there.
I agree, get the DX built with the 425 crank and aluminum heads. Also get the them O ringed and use head studs to keep from blowing too many head gaskets.
T

 

[pencero]

Bill Trovato has a lot of very informative videos on youtube if you search around although many of them have been removed b/c copyright issue unfortunately. W/e you want to know oldsmobile if you just watch a bunch of videos him building olds and listen to what he's saying you will get such a good sense for what you can do/ cannot do and what has already been done before w/ what type of results. He is one of the only mechanics I can actually listen to and learn from on youtube b/c I don't find him boring and redundant. The video where he shows how to fit the big block crank into the DX block was very interesting to me and I didn't even intent to watch more than 10-15 minute of it but it was so fascinating I ended up watching the whole video and learning a lot from it. In another video he briefly touches on turbos and explains why he thinks building a DX block the purist way is the better way to go; he makes a good point that a mistake on a purist DX block is rarely fatal to the block whereas a mistake on a high compression engine can crack the block and result in a total loss of your investment (dont ever forget your engine is an investment b/c it is lol even if its admittedly a bad investment)

I think the most telling thing about his videos is he really cares about the engines he builds like their paintings or something. In one video I recall him talking about how he convinced a customer to go with a smaller bore to save money in the long run on 'his next rebuild' so they could 'get the most out of this block by re-using it 1 or 2 more times' heres a guy that is teaching how to build the engine w/ the rebuild you are not even on yet in mind

 

[81cutlass]

Cool, thanks for the advice. It sounds like a dx block with 425 crank and alum heads is where its at.

Ill glance at the youtube vids.

 

[88hurstolds]

DX block, 425 crank, turbos and E85 will get you there.
I'm working on one now, well collecting parts...
Twin 65mm turbos, EFI and E85 without the need for an intercooler or pump gas and an intercooler, haven't decided yet but I'm going with custom pistons to get 442 ci.

 

[olds307 and 403]

Good choice. You don't need to push the overbore to much, keep the walls thick and more area for the head gaskets to clamp on. O ring and Cooper or MLS head gaskets if the boost isn't extreme. Make sure you do the 4 bolt main cap conversion too. Sounds like an awesome project.