What turbo to go with my ED 66mm for twins

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Deputydog

Proud Fummins Owner
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Jun 19, 2008
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Getting ready to do twins on my fummins.

I already have a 66mm single from Chris @ E.D.. His suggestion for twins was an S475 with my 66, but i was thinking something in the S478-480 range.

Looking for suggestions..

I use the truck for a DD, I don't tow anymore.. Dyno a few times a year and like to play at the track.
 
I'm sure others with more experience than I will chime in, but I would definitely go with at least a 480 w/a race cover... My buddy Adam- (DEZLFREK on here) originally put a 480 under his 64 on his 12v fummins project, and then even decided to go bigger (a forced inductions s491) and it is still a quick spooling combo... since you already have a cam and everything I would say get some good air in there!
 
I have a 64/71/13 over S480 with race cover. Spools quick and will handle 850-900 (even though I am not at that level) 480's are cheap even if you went with one off the shelf with no race cover for under 1k you would be happy. My truck is muuuuuuuuch lighter than your fummins though and that will make yours spool slower than what I am reporting.
 
im not sure if most people realize that the small turbo/ high pressure turbo/ manifold turbo what ever you want to call it is what creates spoolup. its slightly afftected by hanging another turbo behind it but basically if it works as a single it will work basically the same as a staged turbo setup.. that being said if i were you i would not go smaller than a 480 on your setup.. but again just my opinion for whatever thats worth..
 
As a single it will spool quicker as the same turbo in a compound setup.
 
DEZLFREK said:
im not sure if most people realize that the small turbo/ high pressure turbo/ manifold turbo what ever you want to call it is what creates spoolup. its slightly afftected by hanging another turbo behind it but basically if it works as a single it will work basically the same as a staged turbo setup.. that being said if i were you i would not go smaller than a 480 on your setup.. but again just my opinion for whatever thats worth..
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That's the info I'm looking for, so I appreciate the input!

My thoughts are a 480 as well
 
<p>I'm FAR from an expert, but I have learned that the secondary should be 75% the size of the primary...thats how mine is set up (62 or 830. my truck has convinced people to go with twins, as one put it, the power just doesn't stop!</p>
<p> </p>
<p>£ith a 66 on top, put an 88 on the bottom. What variant or a/r is up to you. and dont forget a wastegate. I assume you have an internal, and that works for me, though a lot preach external.</p>
<p> </p>
<p>food for thought I hope.</p>
<p><font size="1"><i>CompD Mobile Device</i></font></p>
 
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My opinion is that a 480 is too small for a 66. Will it work fine, yes, but it's a little small.

Why sacrifice the slower spool-up of running a 66mm on the manifold without gaining top end power from a large 90+ mm atmosphere turbo.

I'll bet a 62 over 480 will make the same power as a 66 over 480 so why penalize yourself with the slower spool-up of the 66? If you're trying to save money and already have a 66, then I understand. Otherwise, go bigger than 80mm on the atmosphere turbo!
 
I also agree that spool-up in terms of 0 to 400 HP is 95% related the manifold charger and torque converter setup. Mid range through top-end power is where the size of the atmosphere charger comes into play.

My He351 (60mm) over HT4B (83mm) drives fantastic on the street. It's easy to spool up at the drag strip, in fact I'm running a tighter than stock torque converter, and it's easy to hold 5, 6, 7, or even 10 psi at line. The power delivery is smooth, very linear, and never chokes out up top.
 
Doesnt the turbine wheel have the most impact on spool up? So a 62 through a 66 will change spool some but the turbine wheel size relates more on spool speed? The compressor size in a compound setup has more relation to bottle necking the compounded charge at smaller sizes than spool up I thought.
 
VMAX said:
Doesnt the turbine wheel have the most impact on spool up? So a 62 through a 66 will change spool some but the turbine wheel size relates more on spool speed? The compressor size in a compound setup has more relation to bottle necking the compounded charge at smaller sizes than spool up I thought.
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not true, its rotating mass and more importantly its farther out from centerline while also theoretically pumping more air which creates more resistance.. a 62/71/14 will spool considerabley and noticeabley faster than a 66/71/14...... i also think that a smaller compressure would not be a bottleneck under boost and with the valume from the lp turbo but may not be as efficient(rpm/heat) under its low boost cynerio of compounds therefore not making as much overall power.. again just my opinion..
 
Hmmmmmm that is what High Tech Turbo Engineer stated to me regarding turbine shaft and spool up. They have a 71/66 in the air dog monster truck. It is suppose to spool lighting fast and needs it with those big ass tires and short pulls due to the small turbine shaft.
 
VMAX said:
I have a 64/71/13 over S480 with race cover. Spools quick and will handle 850-900 (even though I am not at that level) 480's are cheap even if you went with one off the shelf with no race cover for under 1k you would be happy. My truck is muuuuuuuuch lighter than your fummins though and that will make yours spool slower than what I am reporting.
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Im pretty sure the heavier truck would spool faster. more weight = more engine load.

but correct me if i'm wrong
 
spoolup is affected by rpm, lighter truck will bring up a tight converter in dd condition faster than a heavy one.. if the coverter was right and at the track they would do the same at the line. a heavy truck just puts more load under acceleration..

V that 71/66 would surge like a bastard on a street truck, yes it would spool fast but prolly only sees full throttle and idle speeds on the truck.. again any time you add wieght to the ratating mass of a similar turbo weather it be in front or in back its going to take more energy to spool it. physics bro.. cant be overcome unless you have something more efficient like ball bearing turbos or lighter material or smaller housing..
 
of course cams play a big role in spoolup also but in our case for this discussion those staying the same..
 
Gotcha, not saying that the 71/66 would do well on the street was just giving an example.
 
All I know is my 60 over 83 setup has plenty of air and shows no signs of bottle-necking, it cleans up like a nitrous-fed Ford or Chevy.

[ame="http://www.youtube.com/watch?v=umbIav4MOlg"]http://www.youtube.com/watch?v=umbIav4MOlg[/ame]

[ame="http://www.youtube.com/watch?v=GmJ7-DDoSSk"]http://www.youtube.com/watch?v=GmJ7-DDoSSk[/ame]
 
And yet a 62 over a similar 83 with a bit too much fuel is also FAR from a bottle neck. Truck made about 100psi on this dyno run and nearly 800HP. The air was there, but it had not been tuned at this point. After I slowed the fuel down, the SOTP meter showed a considerable increase, it has not been dyno'ed since.

[ame="http://www.youtube.com/watch?v=WbR0njYguz4"]‪TS 2009 795 HP‬‏ - YouTube[/ame]
 
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