LS1TECH - Camaro and Firebird Forum Discussion

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-   -   408 TT sizing (https://ls1tech.com/forums/forced-induction/1912791-408-tt-sizing.html)

turboed370 01-04-2019 05:45 AM

408 TT sizing
 
Ran a pt88 on my old 370 and it worked great! Sold the motor kept the kit and turbo. Put together this 408 with that same old turbo and it's done making power around 5800rpm. Picked up a huron twin kit but now debating on turbo size. I'd like the car to pull to around 6300-6500. Anyone have any recommendations? How big on the turbine side do I need to achieve these kind of rpm?

RealQuick 01-05-2019 11:01 PM

I currently run 6266ís .81 A/r on my 416 LS3. Peak power is around 6k rpm and boost comes on hard. For more rpm you could go bigger turbos or .96 A/r. Graph attached (10psi and 13psi).

what are your power goals?
https://cimg3.ibsrv.net/gimg/ls1tech...fa9ce6373.jpeg

turboed370 01-06-2019 10:11 AM

Dont necessarily have a power goal in mind. Looking for low 9s maybe clip an 8.9. I just dont know how to gauge sizing twins. The car has been 9.6s with the pt88 but my mph was like 137..the car falls flat after 5800rpm. Would like to carry the power out a little further and trap 145+

RealQuick 01-06-2019 12:19 PM


Originally Posted by turboed370 (Post 20026185)
Dont necessarily have a power goal in mind. Looking for low 9s maybe clip an 8.9. I just dont know how to gauge sizing twins. The car has been 9.6s with the pt88 but my mph was like 137..the car falls flat after 5800rpm. Would like to carry the power out a little further and trap 145+

what cam and heads?

turboed370 01-06-2019 05:18 PM

Stock 317s stock ls6 intake. Cam is a custom grind very similar valve events to the ljms stg3

RealQuick 01-06-2019 06:14 PM

That cam probably peaks around 6200-6300rpm with those heads.

A lot of guys running twins... surprised nobodies chiming in.

Game ova 01-06-2019 06:25 PM


Originally Posted by turboed370 (Post 20026185)
Dont necessarily have a power goal in mind. Looking for low 9s maybe clip an 8.9. I just dont know how to gauge sizing twins. The car has been 9.6s with the pt88 but my mph was like 137..the car falls flat after 5800rpm. Would like to carry the power out a little further and trap 145+

I don't think your turbo choice was the problem with the 370. Should have been truckin up top imo, there are guys running 145 with the on3 stuff (7875)..... been 140 in a full weight f body leaving in vacuum at the track. Id say the problem was elsewhere.

turboed370 01-06-2019 11:28 PM


Originally Posted by Game ova (Post 20026409)
I don't think your turbo choice was the problem with the 370. Should have been truckin up top imo, there are guys running 145 with the on3 stuff (7875)..... been 140 in a full weight f body leaving in vacuum at the track. Id say the problem was elsewhere.

137 was with the 408 I beleive I ran into back pressure issues with pt88 and 408...IATs would go insane once I clicked 3rd gear..I never actually measured it but can tell you I did blow out 2 exhaust gaskets from the manifold to crossover.

stevieturbo 01-09-2019 04:54 PM

Cam and intake will determine rpms more than turbos.

subeone 01-09-2019 05:57 PM

turbos will determine rpm more than cam and intake.

GT Griller 01-10-2019 05:17 AM


Originally Posted by stevieturbo (Post 20027966)
Cam and intake will determine rpms more than turbos.


Originally Posted by subeone (Post 20028000)
turbos will determine rpm more than cam and intake.

yea I would figure he doesn't wanna end up with too small on exhaust side. At least that's what I'm gathering from this post. I think hes trying to avoid the back pressure issues that caused his previous set up to fall off at 5800.

subeone 01-10-2019 12:03 PM

he needs a 88/100 or 85/100 for that 408

GT Griller 01-10-2019 01:34 PM


Originally Posted by subeone (Post 20028470)
he needs a 88/100 or 85/100 for that 408

I would agree for a single set up but the threat title says TT.

BlwnLs1GTO 01-10-2019 02:59 PM

No track times but I'm running T-Netics 66/65's with a .68 turbine. The turbine housings too small but puts out a Massive amount of torque. Only pulled it to 6400 and laid down something like 770/880. On the gate, don't remember how much boost pressure.
408 ci BTW. I think if I get larger housings I'll see the HP go up and the torque still be very high.

I'd go with billet turbo's in the mid 60's compressor range with a Med-High A/R T housing.

subeone 01-10-2019 11:19 PM

69/73s in twin config s400 frame

stevieturbo 01-11-2019 03:11 PM


Originally Posted by subeone (Post 20028000)
turbos will determine rpm more than cam and intake.


load of bollox.

Game ova 01-11-2019 03:13 PM


Originally Posted by stevieturbo (Post 20029240)
load of bollox.

Settle down stevie, for us here in the U.S, what is bollox?

stevieturbo 01-11-2019 03:26 PM


Originally Posted by Game ova (Post 20029242)
Settle down stevie, for us here in the U.S, what is bollox?

https://gp1.wac.edgecastcdn.net/8028...jpg?1482128324

subeone 01-11-2019 08:52 PM


Originally Posted by stevieturbo (Post 20029240)
load of bollox.

its true :cool:

tblentrprz 01-12-2019 06:42 PM


Originally Posted by subeone (Post 20029429)
its true :cool:

Please explain


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