sequential or staged turbos, not for the faint of heart

philly said:
no kidding? i would have thought Ti would be the ultimate... go figure. speaking of sidejobs... im gonna replace the lifters in a 2008 silverado this weekend... 16 hours charged. so after that i should be able to breathe again. for a little while anyway
Click to expand...
That's Awesome Phil.

Maybe a Silverado 1/2 Ton 8.5-8.6" Rear for me to overhaul soon.
Waiting for the OK & get it done.
 
Many different grades of Tool Steels made Phil.
Used to be a big problem in Race engines & street engines.
Piston pin failure.
Scienced out by 1980's.
So we don't give much thought today.
Can be an issue still with Huge HP.
 

Very nice post Phil !

I'm having a hard time seeing how the small turbo would not be a restriction
to the larger turbo when they are in series???

 
rick, the smaller turbo in the stage only sees an atmosphere going into the inlet, and then it converts it based on the settings in the wastegate to pressure in the outlet. as far as being a restriction to the VOLUME of air that passes through it... you need to see it as a form of working in a different atmosphere... if the inlet of the smaller turbo is seeing 30 or 100 psi, it would be as if it were functioning normally at an atmosphere something like 100,000 feet below sea level (if such a thing existed) so when we compress an atmosphere with the larger turbo, and seal its outlet path to the inlet of the smaller, we have made our own artificial atmosphere in that pipe. when the smaller turbo sees the compressed air, its just going to ingest it, and compress it further, and spit it out.

also of note, the interstage cooling condenses the already tightly compressed air molecules allowing the passage of more air for a given pipe diameter.
 
Phil said:
... and if you sized the turbos appropriately somewhere around the time the smaller turbo starts running out of breath on its own, the larger turbo will be "lit" and carry you through the higher RPM's
Click to expand...

If they are in series, the statement above is still confusing to me.

Now I can see how there is no restriction placed on the system when they
are configured like in your diagram below. The hot side is in series, but the
pressurized side is in parallel. Is this what we are talking about??? Or are we
getting into all the possible combinations since there are 2 sides to the turbo
yielding 4 combinations of series and parallel.



 

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i seee what you are asking now, sorry... when i say "runningout of breath" what i mean is that the smaller turbo has reached its specified boost and efficiency level. at some point no matter how much more the engine pumps, the turbine cannot ingest any more exhaust, inherent to its size. this is why wastegate sizing and routing is important... to keep that turbo working at that level we need to use the wastegate to bypass all the excess exhaust gasses so that we can still spin the both turbos at the pressure ratio we want to and not be a restriction in the exhaust stream... once the small turbo is at the boost level we want, we need it to stay there, and simultaneously not get in the way of the ever increasing exhaust flow.
 
^that was referncing both the hot and cold sides in series... like you mentioned, when the cold side is parallel its less complicated

instead of "running out of breath i will modify it to something like "reaches its preset pressure ratio"
 
by the way i think toyota and mazda both ran factory setups like that series diagram you posted there in the 3rd generation rx7 and mk4 supra... for what its worth
 
There are some interesting facts on E85 Gasoline Phil on Wilkepedia you should check out yourself.
True octane is not 100-105 As we thought.
More like 94-96 RM/2 Rated in labratory testing.
The current standards of E85 allow 53% to 83% Ethanol per gallon.
Its seasonaly and regional blended different also.
It may have a different corn alcohol content around the USA.
Winter & Spring mixes not likely same.
It also varies widely batch to batch.
Race gas has jumped to $10 per gallon average looking on Yellow Bullet Race Forum.
The good stuff C16 and better with 118-120 motor octane is now $20 per gallon when you purchase a 55 gallon drum.

Methanol is about $5.00 per galllon.
Only consistent reliable affordable high octane fuel left.

AV Gas too but it has its octane limits.
 
I am heading to all the 1/4 mile racetracks around me on the weekends Phil till early November when the tracks close down for the season.
Watch and look over the power adder cars.
By now there should be a few Hellcats in a few Chicago owners hands.
We can bench race all we want.
But real drag races are not won that way.
So far the 707 Hellcat hasn't bench raced.
Its been dynoed rrecent by UTI, actually 758 Flywheel Hp.
Remember stock cam that's mild, stock tune, low boost pressure , non ported heads and intake, & stock tall rear gears.
Chances are we will see 1000 HP from a Chicago area Hellcat owner with $$$ before end of 2014 & 9 second pass on pump gas soon.
 
I do not know how I have missed this thread Phil but glad I found it. You brought some light to me here and better understanding of how the compound setup works. I am interested in how this will play out and yes 30 psi boost seems high to me but not unreasonable for a track day on injection or race fuel or a mixure of both.
 
87vette81big said:
There are some interesting facts on E85 Gasoline Phil on Wilkepedia you should check out yourself.
True octane is not 100-105 As we thought.
More like 94-96 RM/2 Rated in labratory testing.
The current standards of E85 allow 53% to 83% Ethanol per gallon.
Its seasonaly and regional blended different also.
It may have a different corn alcohol content around the USA.
Winter & Spring mixes not likely same.
It also varies widely batch to batch.
Race gas has jumped to $10 per gallon average looking on Yellow Bullet Race Forum.
The good stuff C16 and better with 118-120 motor octane is now $20 per gallon when you purchase a 55 gallon drum.

Methanol is about $5.00 per galllon.
Only consistent reliable affordable high octane fuel left.

AV Gas too but it has its octane limits.
Click to expand...

yea but you arent taking into account the cooling effects it has on combustion, if you go to the track, find an e85 powered car with no catalyst and put your leg in the exhaust stream, what comes out is probably 50 degrees cooler than youre used to.
 
Thats true I really wish e85 was readily available around here. There are a few gas stations with it but nothing convenient enough to use it for a build.
 
What You & me are wanting to do does not come without Risks Phil.
Fuel consistency is very important .
Only safe way to tune for E85 is set AFR for 53% alcohol blend initial.
Then keep tuning on the same batch of E85 Fuel.
Could be a real PIA.

Need a Mule test engine without dumping thousands into to it to test and tune and record real world driving and track 1/4 mile results.
If it blows its a simple writeoff failure.
 
What You & me are wanting to do does not come without Risks Phil.
Fuel consistency is very important .
Only safe way to tune for E85 is set AFR for 53% alcohol blend initial.
Then keep tuning on the same batch of E85 Fuel.
Could be a real PIA.

Need a Mule test engine without dumping thousands into to it to test and tune and record real world driving and track 1/4 mile results.
If it blows its a simple writeoff failure.
 
Both the 70 & 71 Pontiac 455's are too hard to come by & Valuable to blow up testing E85 Turbo charging to the limits.
410 sbc I won't use. My late buds Bills Hotrod gift to me as he was dieing of cancer.
No there.

That leaves the Tall Deck BBC.
Longblock is rebuilt .030" over as we know from earlier this summer.
433 ci now.
Total I have in it is $100.00 when I bought in 1999.
Market value is low.
Even bare block Tall Deck 427 not sellling at $500 on fleabay or Craigslist Chicago.
 
i just was gifted a bare set of iron big block ford heads (d3ve casting) they arent the greatest option for big block ford performance but they were completely free and i am going to try my hand at porting them. finding a big block ford in a junkyard here is fairly common, so basically setting up a bi block ford test mule wouldnt be hard. a bottom end is $150 at the u-pick here locally... i think it could be built up on the cheap.
 
That's Awesome Phil.
Those BBF make some serious Torque & HP dirt cheap.
 
thanks for that info grumpy... i think im going to try to be real nice to an acquaintance of mine who has a flowbench and does alot of headwork and see if he will peak over my shoulder while i carve these heads up. ultimately any shortblock i sit these on will have an overbore, forged pistons and a set of rods all balanced to a factory crank to keep costs down. so the displacement wont be too radical unless something breaks and needs to be replaced with something better.
 
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