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Twin gt40's or single GT55 (91mm)

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Old 08-29-2006, 03:57 PM
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Default Twin gt40's or single GT55 (91mm)

Me and my buddy were having some discussion about what is better.

1. ease of install (obviously both would prob need custom setups)

2. max power on pump.

3. area under the curve

4. spool up time

5. cost of setup

What are your thoughts on the above mentioned setups?

Lets just say they are both on 408's and setup as optimal as possible, regarding a/r's and things of that nature.

We were comparing mysetup to Intimd8rs TT lt1 setup.

any thoughts?
Old 08-29-2006, 04:38 PM
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I am NO expert, but I think:

1. ease of install - Single
2. max power on pump. - Twins
3. area under the curve - Twins
4. spool up time - Twins
5. cost of setup - Single

Obviously when talking about anything there are caviats to every answer, so take my guesses for what they are worth.
Old 08-29-2006, 04:43 PM
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Originally Posted by RyanJ
I am NO expert, but I think:

1. ease of install - Single
2. max power on pump. - Twins
3. area under the curve - Twins
4. spool up time - Twins
5. cost of setup - Single

Obviously when talking about anything there are caviats to every answer, so take my guesses for what they are worth.

I would tend to agree with this list, but "ease of install" could really go either way. A huge single is hard to make fit, and twins is just more work.
Old 08-29-2006, 05:09 PM
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Hard to fit a big turbo like that without cutting the core support up.
Old 08-29-2006, 05:28 PM
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Is it a general consensus that those twins will make more area under the curve then the one Im running (look at sig for dyno graph).

It just seems that mine skyrockets and stays up there.

Unlessthe twins spool a LOT faster thus creating more area under the curve.

He was talking about running a 1.06 A/R on the turbos.

Would that be too large for the turbos on this motor, or would it work well?
Old 08-29-2006, 05:53 PM
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Originally Posted by 2000 Tran Zam
Is it a general consensus that those twins will make more area under the curve then the one Im running (look at sig for dyno graph).

It just seems that mine skyrockets and stays up there.

Unlessthe twins spool a LOT faster thus creating more area under the curve.

He was talking about running a 1.06 A/R on the turbos.

Would that be too large for the turbos on this motor, or would it work well?
So he's trying to one up you?
Old 08-29-2006, 05:54 PM
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I'd bet on the larger GT55 making more peak power on pump gas any day of the week.
Old 08-29-2006, 06:01 PM
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Originally Posted by eviltwins
I'd bet on the larger GT55 making more peak power on pump gas any day of the week.
IMO, both peak power and area under the curve depend on how well the turbo is selected for the application. If you're running at optimum efficiency then they should be equal, but it's easier to find two smaller turbos for a given application, as there are more to choose from, than it is a large single.
Old 08-29-2006, 07:32 PM
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Originally Posted by Pro Stock John
Hard to fit a big turbo like that without cutting the core support up.
Put it in the back!!






Ok guys.... I am joking....
Old 08-29-2006, 07:54 PM
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Originally Posted by LSONE
So he's trying to one up you?
Haha, no.

He is building a 384 stroker though.

we were just discussing that he thinks twins would have "crushed" my under the curve area, while I thought that it would probably be pretty close, but no way crush it.

what size are gt40's anyways, 72 wheels?
Old 08-29-2006, 09:31 PM
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Originally Posted by 2000 Tran Zam
Haha, no.

He is building a 384 stroker though.

we were just discussing that he thinks twins would have "crushed" my under the curve area, while I thought that it would probably be pretty close, but no way crush it.

what size are gt40's anyways, 72 wheels?
My GT40's made the power in my sig on very low boost. I have a lil 347.........lol
Old 08-29-2006, 09:37 PM
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The GT55 will not work well with a 408ci motor.
Old 08-29-2006, 09:52 PM
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did you look at the sig of the guy that started this thread? he has a GT55 and 408 seems to work well.
Old 08-29-2006, 09:54 PM
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Originally Posted by John Wilde
The GT55 will not work well with a 408ci motor.

Why not? I'd like to know the specifics...seems like a 91mm turbo would work well on a 408.
Old 08-30-2006, 11:16 AM
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Singles can outdo twins in about all of those you mentioned. Twins take twice the cash to build and peak horsepower on pump will not be comparable to the Single as they would need to spin faster to keep up at a certain boost pressure and that would increase the intake temp.
Old 08-30-2006, 11:54 AM
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Originally Posted by John Wilde
The GT55 will not work well with a 408ci motor.

This doesnt look like it works together?
Old 08-30-2006, 11:55 AM
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Originally Posted by A DEE O
My GT40's made the power in my sig on very low boost. I have a lil 347.........lol
So your running 8.5 lbs with that setup?

the wheels are 88's, and your running it on a 347?

whats your compression? when do you see full boost by?

any dyno graph to compare?
Old 08-30-2006, 12:01 PM
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Originally Posted by 2000 Tran Zam
This doesnt look like it works together?
Old 08-30-2006, 05:00 PM
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Originally Posted by 2000 Tran Zam
what size are gt40's anyways, 72 wheels?
There are a few variants. The GT4088R uses a 58mm inducer, and the largest inducer straight GT40 would use a 63mm inducer.
Old 08-30-2006, 05:37 PM
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Originally Posted by eviltwins
There are a few variants. The GT4088R uses a 58mm inducer, and the largest inducer straight GT40 would use a 63mm inducer.
so each turbo could be good to about 500-600 rwhp?


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