turbo on a 557 ?

i have most everything to put my 557 together. it is a scat forged rotating assembly. with the scja heads I have it is to be around 10.5 - 1 compression. I came across these parts at a reasonable price. intentions at the time were n/a. I have a 70 model block with 4 bolt splayed caps added. also have a solid flat tappet cam and lifters I bought from mr lem evans. I am thinking the motor n/a would make around 700hp. with a good tune how much more would the block handle. possibly enough for a turbo or 2 at a small amount of boost ? my compression is higher than normally recommended for turbo applications. could that be cured by changing cam and thicker head gaskets ? or is it better to go with what I have and build more hp on a later build. I would like to get up to my blocks safe range...[ I know I am all ready there].. will the block easily handle 200-300 more hp with a good tune and last a while in a street/strip application ? does this seems like a safe doable deal if so what would you recommend ? I have no experience with turbos other than the one on my diesel truck. I understand that if planning a turbo motor from the start it would be with a lot better parts. aftermarket block and c heads billet rods and nice crank and custom pistons and 8-1 compression and a pocket full of money for fuel injection and everything else.. you guys on here have a lot more knowledge about this stuff than I do... so any honest input would be helpful...thanks gary

It could be done of course, but the problem is that with boost, if a little is good, a lot is much better!! Then you'll have a pile of smoldering parts.
You can use thicker head gaskets to drop the compression a little, but it may not be enough just by itself.
You would be wise to install a turbo specific camshaft too, as they are much different than a N/A or nitrous cam.
A blow thru specific carb and other boost only parts will be required.

For ease of building and less money, its just my opinion that it would be best to just build what you have, and put a NOS big shot plate on it!!

I'm not versed well enough to be taken serious, but here's my .02. I'm pretty sure your 10-11:1 compression is not an issue. Read up on some other combinations that have worked, or even on forced induction compression ratio's in general on this forum or others. The older school general thinking of low static compresion for boost is a myth from what I see. There are some on here with solid proven insight for this sort of deal. I wouldn't be afraid to try for 900-1000 boosted power on what you have, with the right details.

Yes. I do understand that my setup at this point would be better to build as is. But I hate to leave possible safe horsepower on the table. I also don't know much about nitrous. Just enough to be dangerous. Being it's is to be a street strip deal I am leaning away from nitrous. Although it would be alot cheaper. I don't like the tanks and filling for a car that will be driven on the street some. I would like to learn more about nitrous but not sure this is where I want to learn. Isn't turbos supposed to be a safer power adder. Also would like to learn about turbos. I don't want to learn the hard way by picking up metal pieces. Between me and my son we have several cars to build and learn on....thanks gary

J.Toney wrote:I'm not versed well enough to be taken serious, but here's my .02.  I'm pretty sure your 10-11:1 compression is not an issue. Read up on some other combinations that have worked, or even on forced induction compression ratio's in general on this forum or others.  The older school general thinking of low static compresion for boost is a myth from what I see. There are some on here with solid proven insight for this sort of deal. I wouldn't be afraid to try for 900-1000 boosted power on what you have, with the right details.

I have read all the posts on this site and few others . From what I have read you are correct. But I figured I would post this up and get several of these guys who do this kind of stuff alot to give me some details/input on what to use. Also maybe does and don't . One thought that i have is if going with turbos i would have to be very careful not to make to much power. The turbo sizes to fit this application would double the power the block and other parts i have would safely handle. So i guess boost would need to be very low...but at this point it is just speculation on my part...thanks gary

J. Toney is right, you CAN still run your higher compression, you'll just have to keep boost levels low (and a water / methanol injection kit would be a nice addition too).
Things that Im thinking of right away would be to O-ring the block and heads, Hard Block fill up to the water pump holes in the block, all the oiling tricks to the block.

You would want to match the turbo sizing to the engines size and RPM. If you're going with two turbos, you want them to spool quickly for street use, you would need a big top end charge!! I would guess that something from a 76 to 84mm would be brutal power!!

BBFTorino wrote:J. Toney is right, you CAN still run your higher compression, you'll just have to keep boost levels low (and a water / methanol injection kit would be a nice addition too).
Things that Im thinking of right away would be to O-ring the block and heads, Hard Block fill up to the water pump holes in the block, all the oiling tricks to the block.

You would want to match the turbo sizing to the engines size and RPM. If you're going with two turbos, you want them to spool quickly for street use, you would need a big top end charge!! I would guess that something from a 76 to 84mm would be brutal power!!

I have the oiling mods done on the block. its not been o=ringed or hard filled but could get it done. I looked at some of those water/methanol kits. if they work as described you get added 30-70 horsepower and up to 25 points in octane and cooler temps, I was guessing 84 or 91mm on twin turbos but that's just going off what I have read about other peoples builds. all those turbos make a lot of power. probably 3 times what I could use. how do they measure power with turbos @ what pounds of boost ?
when they say a 91mm will make 1500 is that at 50lbs of boost or what.

garys gt wrote:

BBFTorino wrote:J. Toney is right, you CAN still run your higher compression, you'll just have to keep boost levels low (and a water / methanol injection kit would be a nice addition too).
Things that Im thinking of right away would be to O-ring the block and heads, Hard Block fill up to the water pump holes in the block, all the oiling tricks to the block.

You would want to match the turbo sizing to the engines size and RPM. If you're going with two turbos, you want them to spool quickly for street use, you would need a big top end charge!! I would guess that something from a 76 to 84mm would be brutal power!!

I have the oiling mods done on the block. its not been o=ringed or hard filled but could get it done. I looked at some of those water/methanol kits. if they work as described you get added 30-70 horsepower and up to 25 points in octane and cooler temps, I was guessing 84 or 91mm on twin turbos but that's just going off what I have read about other peoples builds. all those turbos make a lot of power. probably 3 times what I could use. how do they measure power with turbos @ what pounds of boost ?
when they say a 91mm will make 1500 is that at 50lbs of boost or what.

Well, a 91mm would be small for a 557 inch motor if we are talking single turbo. A single turbo setup would need more like a 101 to 106mm. What I meant to say was you DONT need a killer top end charge if its a street car, LOL
Too big of a turbo will be lazy down low. On the street, you want it to spool up quickly, thus slightly smaller turbo's work great in that respect.

I was thinking of twins.  What kind of boost would it take to make a few hundred hp. 10 lbs - 15 lbs or little more little more with twins. When turbos are rated what lbs of boost are used to come up with the ratings. .

I would think that with twins, you could make 1000 horsepower with less than 15 lbs of boost.
How much power is gained per pound of boost differs with each motor.
Boost, or "Positive manifold pressure" is a result of restriction. Pumping more boost (PSI) into the intake tract is possible because of restriction in the flow path.

An engine with restrictive intake, cylinder heads, and small valves will have more restriction than one with a better flowing intake, cylinder heads and large valves. So a turbocharger pushing boost into the more restricted engine will see more PSI pressure.
A turbo pushing boost into the free breathing motor will see less PSI pressure, with the turbo(s) doing the same amount of work.
Kinda like breathing in as much as you can, then try to blow thru a garden hose.
Do the same thing but blow into a paper bag...your lungs (turbo) are doing the same work, but one is much easier to accomplish.

With only having to run a small amount of boost to get the power needed would block and heads still need to be o ringed ?

For lower boost...15 psi or less, I think you can simply use the SCE "Titan" copper gasket. They come in various thickness, and they have a stainless sealing ring that is overlapped on top and bottom with copper.
I've had great results with these gaskets....although Im not turbocharged, I run a big shot NOS plate, which actually hits harder than the much "smoother" application of boost.

Please for goodness sake contact turbo people for advice.  Find someone you trust and stick with them.

MLS gaskets are the way to go.  We've only used them successfully to 50+ psi and nitrous motors spraying almost 1000hp without failure.  Block and head machining is very important.  We dont o-ring anything but our screw blown promod engines or twin turbo promod/grudge engines.  For the power level you want with a bbf pretty much any head will work.  I would run a garrett turbo pair but won't give specs because people here will say it wont work and ive already done it a few times.  

rule of thumb is to almost double the horsepower with 14.7 lbs of boost.

That will get you thinking.  

whatbumper wrote:Please for goodness sake contact turbo people for advice.  Find someone you trust and stick with them.

MLS gaskets are the way to go.  We've only used them successfully to 50+ psi and nitrous motors spraying almost 1000hp without failure.  Block and head machining is very important.  We dont o-ring anything but our screw blown promod engines or twin turbo promod/grudge engines.  For the power level you want with a bbf pretty much any head will work.  I would run a garrett turbo pair but won't give specs because people here will say it wont work and ive already done it a few times.  

rule of thumb is to almost double the horsepower with 14.7 lbs of boost.

That will get you thinking.  

This is what I mean by those with previous experience.

whatbumper wrote:Please for goodness sake contact turbo people for advice.  Find someone you trust and stick with them.

MLS gaskets are the way to go.  We've only used them successfully to 50+ psi and nitrous motors spraying almost 1000hp without failure.  Block and head machining is very important.  We dont o-ring anything but our screw blown promod engines or twin turbo promod/grudge engines.  For the power level you want with a bbf pretty much any head will work.  I would run a garrett turbo pair but won't give specs because people here will say it wont work and ive already done it a few times.  

rule of thumb is to almost double the horsepower with 14.7 lbs of boost.

That will get you thinking.  

PM Sent...

What chassis/vehicle do you plan on putting this engine in?

Even at 700 N/A horse getting it to hook up on the street is gonna be a challenge especially with how quick a BBF can make torque.

wickettoby1 wrote:What chassis/vehicle do you plan on putting this engine in?

Even at 700 N/A horse getting it to hook up on the street is gonna be a challenge especially with how quick a BBF can make torque.

don't you watch tv. Those street outlaw cars are hooking 3500 horsepower on the streets. Hooking 1/3 of that is a walk in the park...lol

garys gt wrote:

wickettoby1 wrote:What chassis/vehicle do you plan on putting this engine in?

Even at 700 N/A horse getting it to hook up on the street is gonna be a challenge especially with how quick a BBF can make torque.

don't you watch tv. Those street outlaw cars are hooking 3500 horsepower on the streets. Hooking 1/3 of that is a walk in the park...lol

Why didn't I think of that?