Hi everyone

Can it be done?
If so how? i.e. What size (single) turbo, What psi pressure, is an intercooler needed.

How bad will the turbo lag be?

Can you keep the the original block and heads?
What else needs to be replaced? Can you get it done only replacing the crank and pistons?
Would you need to split the single turbo flow to run several catalytic converters?

Thanks guys

 

On what planet is any 572 emissions legal? Are we talking Federal law, or local law? Sniffer, OBDII scan, or full inspection. Not near enough info here for us to be able to say one way or the other.

 

Sorry for the incomplete info.

By emissions legal I meant a sniffer test.
If possible pass a complete HC CO and also NOx test.

 

If it is a turbo friendly cam, and you are on E85 and a good tune... What are the limits on the local test you would need to pass?

 

Good luck making 1500 with a single on a 572.

 

If it will pass N/A it should pass w a turbo. I wouldn't try a single though.

 

It's relatively easy to pass a sniffer only test. Turbo engines will by default have very little overlap on the cam which helps, and like said running either E85 or a healthy dose of denatured alcohol will get almost anything past one. It all depends on if there's a visual, and if so how strict it is.

 

Sorry for the delay in replying. Have been super busy at work these days.
Actually I got conflicting info on the limits, and haven't had much time to dig deeper into this this days.

In the meantime. Supposing a camshaft with only 5 deg or even no overlap at all, what turbo combo would you suggest to get to the desired 1500+ hp goal on E85?

Read more at: https://www.theturboforums.com/newreply.php?do=newreply&p=1895628

Read more at: https://www.theturboforums.com/newreply.php?do=newreply&p=1895649

Why is a single turbo not advised for a 572?
Is is because of the large turbine diameter required?
Isn't lag the only main drawback on such large turbos?

 

Trying to get a large enough turbine is the problem. A G-trim is about as big as you will typically see, and IMO would be a requirement for a 572. Precision can get a G-trim all the way to 2.00, and I see no reason at all why that wouldn't work with a 101mm or 106mm compressor on a 572. You do have options for big single turbos, but man they aren't cheap.

 

I should have worded it differently. Yes, a 572 is obviously going to require a very large turbine, even without much overlap. I just meant I would run twins on that setup.

 

back pressure ratio. The larger the engine the larger the turbine needs to be at any HP level, than a smaller engine.
Lets's say is takes a 408 25 psi to make 1300rwhp (1500ish). Back pressure is 45. Your back pressure ratio is 1.8
On your gigantic engine 1300rwhp will still produce 45psi of back pressure. But because of its size, only needs 15 psi.
You back pressure is now 3-1, and she won't make squat for power. This is in a fantasy world because at that ratio it wouldn't make that power, or it would make something close at 4k.
Depending on room I would consider twins for packaging, as much as I love me some big singles. Not to say it wouldn't work, but you have a shit ton more options in twins.

 

Read more at: https://www.theturboforums.com/newreply.php?do=newreply&p=1896583

Makes sense to go for twin turbo. Thanks for the patience guys.
Besides that, I was looking at a 454 Big block the other day and I just realized the huge plumbing distance required for a single turbo. And the 572 is slightly taller and wider than the 454.

572 Big block crate engines come in two versions the 620 and the 720R
Which one offers the best starting point?

The 620 comes with rectangular-port aluminum heads and hydraulic roller camshaft.
http://www.chevroletperformance.com...2620&engine=ZZ 572/620&sku=12498793&engCat=bb

The 720R has stiffer valve springs and solid roller camshaft although I'm not sure if the heads are actually different. They both have 118cc chambers.

Unlike the 620 9.6:1 the 720R comes with 12:1 pistons which will need to be replaced as well as the camshaft.
http://www.chevroletperformance.com...720&engine=ZZ 572/720R&sku=12498827&engCat=bb

What else would you recommend to swap? The crankshaft? Rods?
What size turbos to use?
What about intercooling?

Once again thanks guys.

 

Why don't you just have somebody build you a longblock for boost and them you won't have to swap 87 things on a brand new motor?

 

I'm not in the market for a 572, but I imagine if I was I wouldn't start with a $14k version that needs parts replaced. If you have the money then go with the 620, get a custom cam and a 1.50 or 2.00 G-trim 114mm and let it eat.

 

^^Do it! I will pay to Join you at the inspection station, the look on their faces will be priceless.

What car is this going into... and what emission standards? Hopefully it is old and you don't need converters.

 

Hi everyone.
Once again sorry for the delay in replying. I have been really busy working at a special project at my job.
I will have some spare time at the end of the month.

I have some questions for you guys.

What size turbos to use for a twin turbo setup? 70s mm?
If Precision turbos were used which ones to choose? Street and race models? Which exact model?

Is it better if crossover exhaust pipes are used?
Do this crossover pipes need to be placed before or after turbos?
And yes, the car will need to use catalytic converters.

If two Precision 825 hp air to air intercoolers were used. One for each turbo / engine bank
Would it benefit from some kind of intake side 'crossover pipe' to equalize pressure among left and right turbos?

Thanks once again.

 

For twins I would look at the precision PT6766, PT6768, or the PT7168. Crossovers with twins are not necessary and would hamper spool. The closer the turbos are to the heads the more efficient the system will be. The shorter the intake tubing is the faster the spool will be as well. Join the intercooler pipes before the throttle body, no need to cross them or join then any sooner.

As far as the cats and performance, use cutouts for the track, or when needed on the street.

 

I love all this awesome planning and discussion that will likely not ever produce a single thing.

If you are serious about doing this, quit putting the cart before the horse. You're worried about 1500hp and passing emissions. Where did you come up with a 572? Hot Rod magazine? Focus, plan, focus. Read, learn.

 

Wouldn't you be way better off starting with a ls based build if you were really concerned about emissions?

 

Would be better off writing Steve Morris a check for $50k and letting him worry about the details.