Thread: blower on a 400

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I have 1966 chevelle and a pro street jeep wrangler I got a few years ago, as of right now the chevelle has pretty stock 402 and the jeep has a small block 400 running around 450 hp. I have decided to put the 400 in the chevelle I do however want to put a blower on the 400. I don’t want to build anything to radical and I don’t plan on building a 1000hp motor but I don’t want to drive around with a worthless blower either. I have never built a blower motor before but I was told this 400 had a blower on it at one time. Does anyone have any suggestions or know how much I should expect to spend?

Originally Posted by TheFroFactor

I have 1966 chevelle and a pro street jeep wrangler I got a few years ago, as of right now the chevelle has pretty stock 402 and the jeep has a small block 400 running around 450 hp. I have decided to put the 400 in the chevelle I do however want to put a blower on the 400. I don’t want to build anything to radical and I don’t plan on building a 1000hp motor but I don’t want to drive around with a worthless blower either. I have never built a blower motor before but I was told this 400 had a blower on it at one time. Does anyone have any suggestions or know how much I should expect to spend?

The 400 sbc is about the last engine I would ever put a blower on.
With their thin walls and siamesed cylinder's this would really make me nervous.
If you are "hell -bent" on this I would "o'ring the block and also have it sonic tested.
If it is a two- bolt block I would also run "splayed" 4-bolt caps.
If you have a good 350 block I would just build a 383
With the thicker cylinder walls you have a much better chance of keeping gaskets.

Originally Posted by erik erikson

The 400 sbc is about the last engine I would ever put a blower on.
With their thin walls and siamesed cylinder's this would really make me nervous.
If you are "hell -bent" on this I would "o'ring the block and also have it sonic tested.
If it is a two- bolt block I would also run "splayed" 4-bolt caps.
If you have a good 350 block I would just build a 383
With the thicker cylinder walls you have a much better chance of keeping gaskets.

I hear you Erik, but I have run 400's successfully for years now. At one time I o-ringed the heads but I found that to be another sore spot. The best way to go these days seems to be with the Cometic gaskets. You can even reuse them. Since I started with them I have had no problems. I run about 550 hp with motor and 250 nitrous.

My current motor is .030 over. I did install splayed caps. I run it on the streets and have about half the block cemented. I keep the cement down about 3.5 inches from the top of the block deck.

I would love to install a blower but I have never owned one and therefore I have subscribed to this thread cause I want to follow it.

If and when I build another 400, I would just start with a New World block. If you want to go with an older block, make sure you go with an 817 block, not the 509 or 511. It has a higher nickel content.

Originally Posted by TyphoonZR

I hear you Erik, but I have run 400's successfully for years now. At one time I o-ringed the heads but I found that to be another sore spot. The best way to go these days seems to be with the Cometic gaskets. You can even reuse them. Since I started with them I have had no problems. I run about 550 hp with motor and 250 nitrous.

My current motor is .030 over. I did install splayed caps. I run it on the streets and have about half the block cemented. I keep the cement down about 3.5 inches from the top of the block deck.

I would love to install a blower but I have never owned one and therefore I have subscribed to this thread cause I want to follow it.

If and when I build another 400, I would just start with a New World block. If you want to go with an older block, make sure you go with an 817 block, not the 509 or 511. It has a higher nickel content.

At or around 800 on a 400 even with all the prep work you have done is an accident waiting to happen.
It is a miracle that it has not blown yet.
We have built a few 400's,412's,420 etc. over the years.
We did the same level of prep work you did and also added deck plugs.
Every one of them ended up cracking right down the lifter valley.
I would guess the only reason they are living is because they are in a street car and you can't hook it up.

Originally Posted by erik erikson

At or around 800 on a 400 even with all the prep work you have done is an accident waiting to happen.
It is a miracle that it has not blown yet.
We have built a few 400's,412's,420 etc. over the years.
We did the same level of prep work you did and also added deck plugs.
Every one of them ended up cracking right down the lifter valley..

I beleive you. One professional local racer said that he could never get a 400 block to take more than 600 hp. I am wondering, do you remember if you ever used a 817 block? Maybe that is the difference!

Originally Posted by erik erikson

I would guess the only reason they are living is because they are in a street car and you can't hook it up.

Actually mine hooks up. I have AWD with a drag radial at each corner

Originally Posted by TyphoonZR

I beleive you. One professional local racer said that he could never get a 400 block to take more than 600 hp. I am wondering, do you remember if you ever used a 817 block? Maybe that is the difference!


Actually mine hooks up. I have AWD with a drag radial at each corner

What transfer case are you running?

TyphoonZR that sounds cool . i do no care much for the ricers and croutch rockets it allways feels so good when you can dust off a bike

i have a 71sbc 400 that is .30 over and i have a 144 weiand blower wanted 2 know if that was a good combo for street use in my 81 Z28 (the sled)and would it be 2 much 2 take it .40 over i will be using kb-30cc dish pistons 4 the lower compression and a 76cc head with steam holes also i have a built 350 turbo with a b&m holeshot 2400 and a eaton posi with 373 thanx

Originally Posted by young audio

i have a 71sbc 400 that is .30 over and i have a 144 weiand blower wanted 2 know if that was a good combo for street use in my 81 Z28 (the sled)and would it be 2 much 2 take it .40 over i will be using kb-30cc dish pistons 4 the lower compression and a 76cc head with steam holes also i have a built 350 turbo with a b&m holeshot 2400 and a eaton posi with 373 thanx

My motor is .040 over so I don't see that as an issue. As for whether that blower is the right one for the 400, I have no idea. What number casting is your motor, 511, 509, or 817?

Originally Posted by TyphoonZR

My motor is .040 over so I don't see that as an issue. As for whether that blower is the right one for the 400, I have no idea. What number casting is your motor, 511, 509, or 817?

it is the 511 4bolt 1

If you look on the bottom of the block of the 4 bolt main on 400's, you can see why those blocks aren't the best for racing. The outside bolts of the maincaps hardly have any material around them and the block is prone to cracking. However for a street application this would be fine, as long as you keep it mild on the boost I'm sure. The two bolt main 400's are a lot better, the main caps are wider than other small blocks already, plus if you ever were worried about spinning bearings you could always get 4bolt splayed maincaps and machined. The two outside bolts are at an angle so they go into a part of the block where there is actually material there.

Originally Posted by 69elko

If you look on the bottom of the block of the 4 bolt main on 400's, you can see why those blocks aren't the best for racing. The outside bolts of the maincaps hardly have any material around them and the block is prone to cracking. However for a street application this would be fine, as long as you keep it mild on the boost I'm sure. The two bolt main 400's are a lot better, the main caps are wider than other small blocks already, plus if you ever were worried about spinning bearings you could always get 4bolt splayed maincaps and machined. The two outside bolts are at an angle so they go into a part of the block where there is actually material there.

oh i c what u mean i was going 2 use it just 4 on the street 2 tear up a couple of blocks then probabley sell the whole car but thats subject 2 change once its actually done (might fall in luv with it)

is a c.a.l (cat) balancer ok 2 use on my motor,what about 1.5 earson roller rockers are they any good

I use the 817 which has a two bolt main cap, but I have the splayed four bolt main caps installed. The 817 is the strongest block of the three made, it has a higher nickel content and weights another 10 lbs. The 509 is good for about 600 hp. I'm not sure about the 511, but probably 500hp.

If you want to go for more than 750 hp, I would buy an after market block.

Originally Posted by TyphoonZR

I use the 817 which has a two bolt main cap, but I have the splayed four bolt main caps installed. The 817 is the strongest block of the three made, it has a higher nickel content and weights another 10 lbs. The 509 is good for about 600 hp. I'm not sure about the 511, but probably 500hp.

If you want to go for more than 750 hp, I would buy an after market block.

no 450 to 500 is what im tryna reach