[Boostedbird]

Another reason for staying a little smaller on the cid is that it is harder to get the exhaust out of a big inch high horsepower engine. If you reduce the engine's size some and use two medium sized turbines that still spool but allow the engine to breathe you can rev it a little higher to make the same horsepower while not having to deal with extra torque on the bottom end. Accurate Tom Vaught?

I should have said turbo selection is easier for the smaller cid. You don't have to run twins. On a big inch engine you probably will need twins to make a lot of power.

[Tom Vaught]

When you get into the larger frame turbos and start spooling them at higher rpm you can run into a thrust bearing issue inside the turbo.

Journal Bearing turbos need a thrust bearing, much like a crankshaft needs one to keep the shaft in the correct location under load.
The more power you make the harder the forces are on the thrust bearing inside the journal bearing turbos.
At some High compressor flow the thrust bearing wears quickly and the turbo needs repair.
It is a combination of shaft rpm of the turbo and the diameter of the compressor wheel trying to move the air thru the compressor housing.

You can fix that issue with a Ball-Bearing style turbo whose design does not need a thrust bearing. More $$$ but can handle higher compressor flow rates with large turbos and higher compressor shaft rpm.

You might run for years with a larger single turbo with a journal bearing and thrust surface if you keep the load on the compressor wheel and shaft by running less boost pressure. Dual Turbos share the load and reduce the loads by splitting the airflow demand across two boosting devices. 30 psi is very common on engines and diesels can see very high boost pressures but for very short times in each gear.

Again engine size is not as critical as the turbos are helping with multiplying the mass flow thru the engine.
Mass flow is what makes power, as long as you add the proper amount of fuel with the mass flow of air.

Typically 1 POUND of AIR will make on average 10 HP. (Some make 9.7 HP, some make 10.2 hp).
If you move 100 pounds of air thru the engine the engine will make 1000 HP.
Does not matter if it is 1 turbo that moves 100 pounds of air mass or 2 smaller turbos that each move 50 pounds of air mass.
But, like you said, the plumbing can be easier at times with packaging 2 smaller turbos and the related systems vs one massive turbo and a 5" down pipe. Drag cars are a different story as the cars are many times built around the turbo configuration. Superchargers package very easily vs most turbo installations.

So you are correct on all of your thoughts.

Tom V.

[ponjohn]

Originally Posted by Boostedbird

Another reason for staying a little smaller on the cid is that it is harder to get the exhaust out of a big inch high horsepower engine. If you reduce the engine's size some and use two medium sized turbines that still spool but allow the engine to breathe you can rev it a little higher to make the same horsepower while not having to deal with extra torque on the bottom end. Accurate Tom Vaught?

I should have said turbo selection is easier for the smaller cid. You don't have to run twins. On a big inch engine you probably will need twins to make a lot of power.

and you get more sealing space for the head gaskets.

[GTOGEORGE]

Originally Posted by Tom Vaught

Here are a few facts:
A 281 cid engine with Turbos has run 5.7s in the quarter mile. A 670 cid turbo engine might run 6.00s because the same sized turbos are not seeing the same load as the 281 cid Turbo engine.

Tom V.
.

Everything being equal a larger 480-540 CI turbo engine will out perform a 281 cubed Turbo engine easily!
A turbo car will never out 60’ or 330’ a supercharged car!
I only have a 3:73 gear in my car....I probably could go to a 3.50 if I wanted to and it wouldn’t miss a beat!

GTO George

[Tom Vaught]

OK George, You have a Pontiac so lets compare Pontiacs.

You have a 520+ cid engine with a supercharger on it. Marty Palbykin had a 406 cid Turbocharged engine.

You have a Ported High Port Head I believe you have posted about What is the head flow on that head? Must be more than 340 cfm as E-Heads can go 340 cfm all day long and you say E-Heads are chit.

Marty had a 240-260 CFM Cast Iron Pontiac Head. So you have a 100 cid bigger engine and 100 cfm better flowing head

You say you make over 1200 hp.

How come George, the expert on turbos and superchargers, that you run low 8 second times and Marty ran 6 second times with less head flow, (cast iron Pontiac Head) less cubic inches, both of you on methanol, and you say the supercharger will beat the Turbo car.

BS George. You do not have a clue. Just like to argue just like Charlie said. The topic is about Turbos, you have never run a Turbocharged vehicle, so stay out of the thread with your comments. As they are just BS anyway, Just like your knowledge of Street Racing. Never saw you down on 12th Street in Detroit.

Tom V.

[GTOGEORGE]

Only 11 lbs of boost and my car is heavier!


GTO George

[GTOGEORGE]

Actually I’m running 11 lbs of boost for around 1,200hp and Marty’s car had 1,600 hp and what around 40 lbs of boost...he should have had around 2,000 hp plus with his twin turbo engine! Just saying!


GTO George

[charlie66]

Originally Posted by GTOGEORGE

Actually I’m running 11 lbs of boost for around 1,200hp and Marty’s car had 1,600 hp and what around 40 lbs of boost...he should have had around 2,000 hp plus with his twin turbo engine! Just saying!


GTO George

But george , You have better flowing heads . It make a differnce ...

[charlie66]

And whats the difference in your cam sizes ??? Means alot buddy!

[GTOGEORGE]

Originally Posted by charlie66

But george , You have better flowing heads . It make a differnce ...

Charlie.....boost is boost and I have a small cam in my engine....ie Bracket engine!


GTO George

[charlie66]

Boost is boost when you're comparing equally. If you have more lift and duration it will pass more air at that same boost level same with head flow. So in that case boost is boost is true but one will have more air with that same pressure which yes makes it boost is boost but it will potentially make MOORE power!! Just sayin......

[GTOGEORGE]

Originally Posted by charlie66

Boost is boost when you're comparing equally. If you have more lift and duration it will pass more air at that same boost level same with head flow. So in that case boost is boost is true but one will have more air with that same pressure which yes makes it boost is boost but it will potentially make MOORE power!! Just sayin......

Charlie I swear I know how boost works, I’ve owned 3 blowers and been running them since the 80’s.....there are so many variables but you guys are asking the questions and I hate long post so I try to make my answers short! We are not talking apples to apples, I have a Bracket car that WILL go 12 Laps in a day (he probably never made 12 passes in a month) and 3 back, to back, to back without lifting the hood or adding fuel! His is an pro mod..no apple to apples!


GTO George

[charlie66]

Well if you know, then you know im right...

Me mentioning this is because you keep saying CI is the limiting factor when its not ... Especially for the street . Why do you think chief is getting bigger flowing heads.....

[GTOGEORGE]

Originally Posted by charlie66

Well if you know, then you know im right...

Me mentioning this is because you keep saying CI is the limiting factor when its not ... Especially for the street . Why do you think chief is getting bigger flowing heads.....

.........and what else is he getting, we don’t know now do we? Yes a bigger engine will make more HP....and you should know that!



GTO George

[charlie66]

Originally Posted by GTOGEORGE

.........and what else is he getting, we don’t know now do we? Yes a bigger engine will make more HP....and you should know that!



GTO George

You seem to luv to twist george . I do know that. Point was no more cubes needed for the list..

He already bought a new block a year ago . Everyone knows that..

Bet this one stays in his car this whole season. So lets wait and see if he gets the 1 spot back .. Im sure he will with his so called by george too small not getting it done 481 cube underachieving motor ... Just sayin.....

[GTOGEORGE]

Originally Posted by charlie66

You seem to luv to twist george . I do know that. Point was no more cubes needed for the list..

He already bought a new block a year ago . Everyone knows that..

Bet this one stays in his car this whole season. So lets wait and see if he gets the 1 spot back .. Im sure he will with his so called by george too small not getting it done 481 cube underachieving motor ... Just sayin.....

I never said chiefs engine was an underachiever it is a bad a$$ it just didn’t make the power Ryan’s or monza’s engine does! He won’t see no.1 unless there’s a sh_t happens scenario!


GTO George

[charlie66]

Originally Posted by GTOGEORGE

I never said chiefs engine was an underachiever it is a bad a$$ it just didn’t make the power Ryan’s or monza’s engine does! He won’t see no.1 unless there’s a sh_t happens scenario!


GTO George

Mann! You are going to be sorry you said that. Hes going to #1!

[ponjohn]

For this conversation what two turbos would one recommend.

I'd prefer BW because of the cost - seem to be priced real fair and better than offshore products.

[Tom Vaught]

Harry's Precision Turbos company was purchased by Turbonetics. They have been friends for many years.
Harry is like a Track Consultant for them on the Race Stuff these days. Both companies are still in business. Great Guy.

So then you have the Borg Warner Stuff.
You can get Ball Bearing Turbos and good wheel designs from BW but not necessarily the latest and greatest parts from them.
It Depends on your Budget really.

Years ago Rodney Butler wanted two turbos for his engine. $$$$ for the turbos from Turbonetics.
I worked a deal with Turbonetics so that Rodney purchased one 91mm Turbo and they donated one 91mm Turbo to expand the Pontiac market visibility. He ran those turbos for years and years. Deals like that do not happen often in the Pontiac world these days.

Depending on your HP goal maybe you can still get some good Turbos from Turbonetics or Harry or Borg Warner.
It is all based on the parts inside the turbos. Talk to other Turbo Guys, running the same HP level you want.
I believe Richard Guido has gone Turbo(s) now.

Tom V.

[GTOGEORGE]

Originally Posted by charlie66

Mann! You are going to be sorry you said that. Hes going to #1!

I’m not going to be sorry....h_ll I root for him, I am a Pontiac guy!!



GTO George