I have an olds 403 that im thinking will be around 500hp. i wont be spinning her over 5500rpms. i have an olds forged 330 crank an i wondering if i should use it or not? its heavier than the stock 403 crank and im dont know if that would put more pressure on the windowed mains or not?

 

It takes quite a bit to get an honest 500 HP out of a small block. I feel no matter which crank you have in a 403 is not a good situation.

 

Sorry you feel that way but im still going to be building one and unless you have personals experience with this engine your help is not wanted. The 403 is not an all out race engine obviously. They have potential to be an amazing torque happy street motor That will fry the tires of of anything.

 

Big blocks make horsepower easier. Thats a no brainer. but small blocks are not that difficult to aquire 500 hp. all it takes is money and a little bit of smarts.

 

Mmmk... so if you know all this already, what is the reason for your post?

I guess you didn't notice the guy you're slamming happens to race a small block in the car in his sig with the front wheels in the air? I think he might have some personal experience.

380racer was attempting to point out that, in his opinion, even if you stuck with a lighter crank a 403 block might not put up with 500HP for very long. I would extrapolate from this that a heavier crank has the potential to make things worse, although I'm no engineer. Perhaps the fact that the assembly is balanced is more important than the overall weight.

But hey, it's your time and money so do what you want. There's no reason to be an ****, though. The guy was actually trying to offer some useful advice.

 

i know he has experience. I didnt say he didnt. I didnt ask though for someone to tell me this engine wont work i asked for advice on how to make it work. Thanks though. If you have no advice for me on the 403 then your post is not wanted. thanks

 

i just wanted to know if 380 racer has experience with the 403 engine. I dont think theres a 403 tucked under the hood of the car in his pic

 

Thank you jslabotsky. Yes I have alot of experience with SBs. But since you know it all already........go ahead, you will find out just what it cost and the knowledge it takes to make an honest/no BS 500 HP.

 

i never said that. your twisting my words and u didnt answer my question. I asked if you had personal experience with olds 403's not small blocks

 

I'm with 380 racer on this one. To get 500 hp out of a small block it's gonna take a fairly narly combination of parts and isn't going to be a very happy street motor I.E. lots of time under the hood, not one to drop in and forget about. People may get 500 ponys out of these motors but nobody talks about how long they last at that power level. I wanna see a dyno sheet if you get this one done... :P 500 hp at 5500 is gonna be hard to do, i don't think you're gonna be at 500 ft lbs on a stroke that short either. Olds 403's besides having windowed mains have a siamese(sp) cylinders which causes heat issues and if you're planning on running any kind of decent compression the head gaskets have a tendency to blow out. I think the stock 4a heads have around a 85 cc combustion chamber and had a comp ratio of around 8.5 to 1 or less I think. The stock big block heads have around a 80 cc chamber so either you're gonna need a custom piston or you're gonna have to shave the hell out of the heads and as far as the porting goes, unless you know what you're doing you can hurt a port job just as fast as you can help it..
I've read that the only intake that works if you use big block heads is the rpm airgap and it won't fit with the shaker on the TA.

 

ive got the kb pistons and a copper head gasket. My compression will be around 9.5:1. look up 403 Olds 9.70 compression 491 hp 489 tq on google images. It can be done. That motor is using the cast pistons and 7a heads. As long as i make hp in the upper 400's im ok with that.

 

on the 455 c heads if you just make an effort to clean up the bowl and chambers and polish the exhaust ports they will flow very well. I have the rpm intake. plenty of meat to port it out. With the right cam and stall converter it would be a very happy fun street motor.

 

That link takes you to one of the biggest crooks in the Olds world!!

 

lol why is that?

 

He seems like a really nice guy. Hes helped me alot. I was going to have him coat my headers

 

crook or no crook look at that dyno sheet

 

having quite a bit of time running a dyno I can say that they can be made to say just about whatever you want them to say. There's so many ways to manipulate numbers on a engine dyno.
The engine dyno is a good tuning tool and a good way to get a rough idea if what you did worked.
A chassis dyno or on the racetrack is where you really are.
people get really caught up in numbers on the engine dyno it seems.
By all means build what you want, but those things still scare me.. :P

 

11 flat is the number I want to see. At the track.

 

I have known Terry for years.........all I can say is you've been warned!!

 

Some people just have to learn the hard way.

 

any idiot wanting to get 500hp out of a 403 is a troll,ignore him

 

wow i thought this site was to help people wih engine builds but apparently its where a**holes and post idiotic comments and only have negative feedback. *******!

 

apparently you guys know everything and are the best engine builders in the world

 

as far as terry goes. I dont know him so i cant say he is or isnt a crook but 380 racer is the only person that ive heard negative things about him from. 380 racer, are you telling me that Terry doesnt know anything about how to build a 403 and that 500 hp isnt possible? All i asked for was how to acheive it. I like to think positive. All i got back was negative stupid comments that were no help. thank you

 

You don't listen so good do you? I said it wasn't going to be as cheap or as easy as your cocky comments made it out to be. The next time Terry sticks his head out of that hole he's hiding in........ask him when Willem is either going to get the parts he paid for or his $3845 back. There are many more examples too. Also ask him how many motors has he blown up on the dyno. I saw one 403 his boy ran over the crankshaft. Getting the idea?

 

Gentlemen, Please let's all go out side have a cold one and cool off. Thanks

 

outside?
it's 10 degrees.

 

The war room for this kind of stuff is over on Realoldspower.com


Dman, I think the bottom line and general consensus here is that 500hp is a lot to ask out of a 403.

It probably has been done, but that doesn't make it the best idea.
Take a look on this chart, and there will be no 403 blocks running 11 flat or better.

http://www.arrace.com/The_List_11-20-09.pdf

You can use a 350 block and make it into a 403 with a custom crank if you like.

403 motors were smogger grocery getters that needed enough torque to get the heavy cars moving along cheaply.

 

Or grab a diesel block if you want to be different and have a rock solid foundation to build on. I don't think anybody's gonna deny that getting 500 out of a 403 is possible, but it's just a ticking time bomb, a shaky foundation at best. 500 horse out of these old motors isn't "easy" as it seems. as to the original question of this thread, as long as the crank is well balanced the actual physical weight of the crank isn't going to matter that much.

 

Good,

Maybe they'll cool off quicker.

 

I don't think a 403 is a good canidate for a 500 HP street engine. You have to respect it's limitations. An honest 350-400 HP SBO is a more realistic goal. Trust me, even at those power levels, you'll be able to roast your tires at will. You can even enhance your 403 by adding a forged 330 crank, or a nodular iron SBO 350 crank, along with a set of LIGHT forged SBC 6" rods & custom pistons. I'd go with a nice set of #5 heads too. Also, keep in mind, TORQUE is more important than HP for a "street light to street light car." Additionally, too much power can be downright UNSAFE for a street driven car. It's good to get input from other folks (it can save you headaches/$$$$). There are alot of seasoned Olds folks on this forum. Try not to take stuff personal.

 

A 403 is a perfect candidate for a 500 HP, 11 second engine! Hell I got 700 HP out of the 307 in my 1990 Buick Estate Wagon. All I did was run 91 octane gas and a Vornado (the ones Billy Mays sold) in it. I am sure if I took it to the track it would have run 10s easy!

FWIW, I know nothing about the topic. I just like making wild, unsubstantiated claims about Oldsmobiles in an attempt to diffuse the situation.

 

I drove a friend of mine car. It has a built 403. In his words the fastest car he ever owned. It has built 403, th350, and 8.5 with 3.73 gears in a 83 Cutlass. It's only around 375 hp. He used a 350 crank and heads from a 71. It has 10 to 1 compression. Headers, Preformer RPM intake, and 750 Holley. It's pretty good combo runs good for a street car that's all someone would need.

 

Good to know.

In fairness, it can be hard to tell whether folks are genuinely trying to save you from a bad experience or just being a know-it-all. So I kind of understand where Dman is coming from.

Dman, if you are looking for a recipe for building a 403, have you looked at the Engine Builds\Combos section on realoldspower? That's about the only place I've found it easy to dig up information about specific combos.

 

No more fighting from my camp but, if he would have been civil to begin with I could have sent him to somebody who runs in the 11s with a 403.

 

Dman-
The difference between short blocks in what Nick runs, and what you want to run is bore size, and how much material is supporting the crankshaft.

When he talks, I suggest you keep your ears open, and do not interrupt.
Take notes, too.

If he has a suggestion, I really advise you take it and run, it will only save you time, money, and hassle.
Once again, my opinion.
Jim

 

To be honest to build up a 403 to handle 500 hp is going to cost a lot. It would cheaper to by a 383 Chevy crate engine maybe that would be your best bet. Olds engine are not cheap that's for sure. The only reason we build them is because that what came in the car, and different from what everyone else build. Because of that you limit yourself. Because of the lack of aftermarket parts. If you want to know how to build a 403 to 500 hp contact Dick Miller Racing he's on the net.

 

X2. The 403 he built for Engine Masters a few years ago hit 599 HP. It would also cost $13K to duplicate - then. Inflation has probably raised that number.

http://www.popularhotrodding.com/eng...ine/index.html

 

Just out of curiosity, what kind of mileage do these engines run ...

I had a 351c Ford that got 6 mpg ...

 

This a list of the things being done to my 403. I have everything. I just need to finish putting it together. Block is bored .24 over with kb pistons. oil restrictors in main saddles. main bearing holes elongated to line up better with feed holes. Melling high volume oil pump with deep pan. rods polished and shot peened. 330 forged crank ground .10 under. Im going to use J&S main support but dont know if i should use the 5 main girdle or full block girdle. Full block girdle is expensive and might be overkill. cam is comp hydraulic roller. lift is in mid 500's and duration is in mid 230's. lsa 110. dont have exact specs yet because cam is being reground. roller lifters. 455 C heads with exhaust ports and chambers polished. Bowl port blend. 2.075 int valves and 1.710 exhaust valves. with heads milled compression should be just under 10. comp magnum 1:6 full roller rockers. oil restricting pushrods. edelbrock rpm intake and holley 750 dp with choke tower machined for improved airflow. electric fan and water pump. msd ignition and headers. I know there are many other better engines i could i choosen to build but there is a reason i want to build this one. My father passed away and left me with his 79 t/a. its been through the family and need a little tlc. I want to be different and build up the 403. I dont really care about the horsepower i want to get as close to 500 ft/lbs of torque s possible. torque wins races.