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Turbo and converter recommendation

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Old May 7, 2010 | 01:46 PM
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Default Turbo and converter recommendation

Ok, please, forgive me if a similar setup has been asked about before. I am new to FI and have used the search function to read about a LOT of different combinations....quite frankly it's a bit overwhelming....given the Ls conversion as well.

I am in the process of installing an iron 6.0L with 243 heads, Zo6 intake and DBW throttle body into my 69 Firebird backed by a built 4L65E. I have decided to run a twin turbo. Yes, I know a big single will get me to where I want, but I have plenty of room under the hood and WANT twins. I'm looking for converter and turbo recommendations....

My combo consists of the following:
6.0 Iron block (supposedly built for boost) - installing ARP studs and MLS gaskets.
243 heads - mild port clean up
Patriot Gold springs
EPP FI Cam
LS2 oil pump and timing chain
4L65E trans
4.10 Rear end

My goal is 800rwhp and 9's in the 1/4 in a 3500lb car. This is a pro-touring car, so primarily used for cruising, but I do take it to the track regularly.

I was thinking about having 2 ECMs and an electronic boost controller. One tuned for street and around 7-8 pounds of boost and one for the track running race fuel and ~18 pounds.

Thoughts?
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Old May 7, 2010 | 02:14 PM
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Sounds like a decent setup, might want to go with something like MP70s with a .68ar, but if you want to reach your goals you might want to make that rear gear a 3.00-3.50.

Last edited by RS_SS69; May 7, 2010 at 03:25 PM.
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Old May 7, 2010 | 02:22 PM
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The trans most likely will not hold up very long either. 800rwhp on a 4L65 is a time bomb pretty much no matter who built it. A 4L80 would be much better suited and would match your rear gear better as well. You may want drop the gears in either case.

As far as turbos, 60s or 70s would get you there. 800rwhp is gonna be tough on 18psi and stock heads but it might be doable. It's going to be very hard making that power through an auto with your hardware though. I would build a sweet fuel system and run E85 all the time if it's available near you.

Coverters are not cut and dry on turbo cars. It's usually a process to get it dialed in correctly. I'd start around 3000 and go from there.
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Old May 7, 2010 | 02:43 PM
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You should rethink the transmission choice. Sell it while it still works. Also, the gears should be much lower. I would use a traditional 3 speed and and gear it way up to 3.08-3.25. Just about any twin setup that you choose will have more than enough torque to get you going with the tall gear. Then call FTI and tell Greg what you are doing. He will send you the correct converter. They also make 4L converters if you insist on putting that POS in your car.
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Old May 7, 2010 | 03:02 PM
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Thanks for the feedback guys. I'm a bit confused. Granted, I am used to running a NA Pontiac 455 that makes tons of torque through a TH400 and a 3.42 rear gear. I want something I can cruise on the freeway and kick *** at the track, thus the OD trans and taller gear.

This 4L65 was built for a boosted application and it's fresh. I know the 4L80 would be a stronger starting point, but if this one has been built to handle it, does it make sense to make the swap?

I suppose I could always keep the TH400 and have it freshened, but I really wanted OD.
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Old May 7, 2010 | 03:35 PM
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Originally Posted by Drewhelm
Thanks for the feedback guys. I'm a bit confused. Granted, I am used to running a NA Pontiac 455 that makes tons of torque through a TH400 and a 3.42 rear gear. I want something I can cruise on the freeway and kick *** at the track, thus the OD trans and taller gear.

This 4L65 was built for a boosted application and it's fresh. I know the 4L80 would be a stronger starting point, but if this one has been built to handle it, does it make sense to make the swap?

I suppose I could always keep the TH400 and have it freshened, but I really wanted OD.
well if you lower your gear ratio by 25%. its the same as adding overdrive, haha
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Old May 7, 2010 | 04:59 PM
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Am thinking a pair of Precision 62mm .68 ar would suffice. ??
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Old May 8, 2010 | 01:27 AM
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Those turbos would be fine... I might step it up to a .81 though.

As I said before... I don't care who build the 4L65 to handle XXX hp, it ain't gonna last very long at 8--rwhp no matter what.
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Old May 8, 2010 | 02:14 AM
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Turbo 400 and 3.08 like was said very strong and be almost like overdrive. I like my combo of fully built by RPM 4l80 and 3.54 gears. I like a bit more gear off boost and driving arouind town. My car is heavy it likes some gearing. I have yank py3400e stall. Lots of very fast guys run that stall.Seems pretty good around town .Find out how it does at track hopefully this season. My build is set to run about 800rwhp daily and maybe try to hit 1000rwhp for dyno bragging rights. I could do more with the spray and turbos I have but not really into it on just basic 408 iron block . To go much past 1000rwhp would like to have LSX build and 6 bolt heads and would need to upgrade the fuel system more.
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Old May 10, 2010 | 10:59 AM
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Would 2 60mm turbos with .96ar work?
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Old May 10, 2010 | 07:55 PM
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id try to go a little bigger than 60mm if you can, 60 will get you to your power goal but not as efficiently as a larger turbo, i think the corvette guys are having pretty good luck with precision 62's like you said earlier, the bigger A/R on the 60 isnt going to help compressor efficiency. honestly i just did a 346 with twin 57's due to space constraints and it worked out great so you'll be fine with the 60 or 62
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Old May 10, 2010 | 08:09 PM
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Originally Posted by Drewhelm
Would 2 60mm turbos with .96ar work?
Yes. I had twin 60-1 turbonetics turbo's and @18psi made 922rwhp and @ 22-23psi made 1089rwhp, but this was thru a 6 speed. When that setup was originaly done I had the 4l60e as well and @18lbs i had made a little over 800rwhp but the tranny lasted 2 weeks in my f-body.Hence why I switched to the 6 speed.
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Old May 10, 2010 | 08:15 PM
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Twin TC6262 would work very well on your setup and leave a little breathing room.
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Old May 10, 2010 | 08:19 PM
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TC76 would make good power and spool fast!
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Old May 25, 2010 | 04:23 PM
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Originally Posted by HUNTER02SS
Yes. I had twin 60-1 turbonetics turbo's and @18psi made 922rwhp and @ 22-23psi made 1089rwhp, but this was thru a 6 speed. When that setup was originaly done I had the 4l60e as well and @18lbs i had made a little over 800rwhp but the tranny lasted 2 weeks in my f-body.Hence why I switched to the 6 speed.
Exactly what I am looking for! One minor change to my combo....a cnc ported set of 317's in place of the 243 to drop compression a bit.

Still thinking the 60's will suffice? Also looking at keeping the TH400 with 3.42 gears.
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Old May 26, 2010 | 10:23 AM
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You can enter in gear calculators for tires,etc. But think turbo 400 with 3.42 will hurt you in the quarter big time. Now not sure maybe you can run 30s under that and that could help. Even 28 inch tires would help. Have to go crunch the numbers. As said most guys if they want to do much highway and to keep high top speed for 1/4 usually go with like a 3.08 for the turbo 400s. 4l80 has of course overdrive and think I can squeak around 140 from mine on 26 inch tires have to check the calculator and also that depends on converter slippage. I didnt built a 1/4 mile car and dont' really care if car shifts to overdrive at the track. I also wanted to turn reasonable rpm on the highway.

Or you could decide to lower your goals to mabye 600,650rwhp and then maybe you can keep that 4l65 alive or you can of course see what that current trans can take.
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