Light84vette

I plan on selling my car and buying a 1986 vette. IT has a 406 and the owner tell's me it has a 406CID, dart heads and 10.75 to 1 compression on a 4+3 Transmission. How much power can this thing be making? Oh yeah it also has a Superram on it and hooker headers--No smog parts. :D Any info is appreciated, thanks :yesnod: :flag

Darkness

Any info on the cam?

CorvetteZ51Racer

Send me all of the specs you know, like header size, cam specs, which heads, and have they been ported, etc, etc, and I'll make a model of it on some GOOD simulation software (much better than Desktop Dyno) and tell you what it should make at the FW.

sumoboy

I don't know but ski_dwn_it will give you an idea what a 406 can do..little higher comp . http://forums.corvetteforum.com/zerothread?id=537390 :eek:


[Modified by sumoboy, 6:29 PM 4/14/2003]

Light84vette

Sorry guys, all the info I got was that it was a 406CID, Superram, Hooker headers, and Dart Heads, and it was at 10.75 to 1 compression. That was it, If you could put some regular cam specs, and I'd say maybe 190cc or 200cc on the intake runners. I wouldnt know the rest, thanks for the quick responses :yesnod:

CorvetteZ51Racer

Too many variables to give you any kind of decent ballpark figure for that. If you can find out more info, I'll make a model for you, but without cam and head data, the model would be meaningless.

Light84vette

Thanks for the help anyways, I guess I'll just have to guesstimate :lol:

LT-4 CE

I have built several 406s and depending on the cam grind, you should be able to make an easy 400 + hp. My last one was 11.75:1, has Dart 200 cc runner heads, 2.02 valves, and a .550/.571 lift cam and made 479 hp on the dyno.

Light84vette

But that 406 has to be on a 400block. ANd that can be stroked and bored to even more cubes right? Is 427 possible? Or has it been bored too much? Its a 4.155' and a 3.75 stroke.

LD85

My 406 using DD2000 with 10:88.1 comes out to (estimated) 496HP @ 5500 and 514TQ @ 4500 RPM using a mild .225/.233 cam.

0ski_dwn_it

See if you can get some more details from the guy. I would check it out quite a bit before committing. Take it to a track and see what it cranks out. :thumbs:

Light84vette

I'm going to have to talk to him tommorow and find out some more information about his Corvette. Also, does the 400block come in 2 bolt mains and 4 bolt mains? Or all 4 bolts? Plus how much of a difference in weight do the 350 and the 400 block have?

Thanks for the help guys, nearly 500HP is plenty good for me, All I need is more then the stinkin 205HP from this Crossfire :lol:

CorvetteZ51Racer

If memory serves, all OEM 400 blocks were 2 bolt mains. The weight difference between the 350 and 400 is negligeable, as the blocks themselves are physically the same size...the difference is in the cylinder walls themselves and the larger main bearing journals.

Light84vette

Yeah, Im going to have to call him and findout if it was an OEM block or a Aftermarket, Thanks :yesnod: BTW, how much power can the 2 bolts take anyway? :confused:

LD85

It depends on a few things like the crank, stock or forged?

LT-4 CE

There was one casting number for 400 blocks that had 4-bolt mains and I think it was offered only one year. Of the 406s I've built only one was a factory 4-bolt. Actually, many people prefer to start with a 2-bolt and use after market splayed caps to make a 4-bolt. My last one, 479hp on a dyno (500+ on Desktop dyno), was a 2-bolt with ARP studs. Seemed to work just fine.

As for boring to 427, you may be able to do that with an aftermarket block, but most people do not recommend going more than 40 over on a GM block. Once you start to get to 60 over, the blocks are prone to core shift. You can build a big small block with some of the aftermarket blocks.

There should be no problem buying this motor used, but you should check all the specs and make sure he has a detailed list of every part and the specs. For example, you would definitely want the cam card for future referece. If he can't provide all this, I would be a little leary.

Good luck.

LD85

My engine builder does not recommend stroking the 2-bolt 400 at all.

MrJay

What kind of Dart heads is on the engine? because the smallest ally head they have is Pro 1 200cc but if it is cast iron then they have some that are 167cc, since it is on a 406 I would think he went with heads with 200cc or more.
LR-4 CE is right lot of engine builders use 2 bolt block and put 4 bolt splayed caps on it but some just use the 2 bolt block and they are making lot of HP with them...and yes do not bore them more then 0.040.
But there is nothing wrong with stroking them, a stock 400 is 4.125 bore and 3.75 stroke but this engine is 0.030 over 4.155X3.75= 406 if you put in a 3.875 stroke crank (the 396 crank) then you will have 421ci 4.155X3.875= 421 to put that crank in you have to clear the block just a little, you can make a 434ci out of that block it looks like this 4.155X4.00= 434 if you build one like this then you will have to get a lot of custom parts ( cam, rods and pistons ).
But it is better to go with after market block because they are stronger but the cost is high on them $1600-2200, but the stock block is a good block for being 30 year old.

The hardest part of building a 400+ engine is to find a block that is good and not cracked.

This engine should have over 400hp.

Here are some pic of a car that has a 434ci engine that my brother built from a 2 bolt block.





He used a stock GM block....this engine used 200HP nitrous on it.

Jay

PS I know it is not a Corvette just wanted to show that the stock block can make good HP numbers, just look at ski_dwn_it car and Corkys car they both have 406ci in a Corvette and are making good number and running really strong.


[Modified by MrJay, 8:52 AM 4/15/2003]

Klamath Stoogie

Not true, I have a 4 bolt main OEM 400 sitting in my basement. :D

StealDads67

.... No twin turbo set up?!?!?!?!