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Discussion Starter #1
OK guys, help me decide the fate of my poor little street Mustang...

Here's my combo, so you know what I'm working with:

Man O War 331 short block with all forged stuff, 8.8 to 1 compression

Eddy Victor JR heads, healthy turbo hydraulic roller cam shifting at 6800 rpm

Rossler TH400 with PTC converter, 3.27 gears

Currently running a single PT76GTS turbo. Last year car ran [email protected] with 18 psi...I'm guessing the car might squeak into the 8s maxxing the 76mm turbo out on race gas. Who knows???

My issue is that I don't want to go to a mid frame turbo like a borg warner because I just don't have the room for the big down pipe among other things that would have to change.

I'm considering selling my current single kit and purchasing a twin turbo kit to get my car solidly in the 8s...8.50s?? and still be a true street car like it is now.

Are twins the way to go? If so, what size turbos?? Currently, I'm looking at two Turbonetics 6668 turbos, they support 700 hp each, which should get me to my goal of 8.50s with some room to grow.

Also, keep in mind that I will more than likely be going to a big bore 347 piston on my next motor rebuild.

It just seems like the turbo manufacturers all say a large single is more efficient than two small turbos, but I see some really fast street cars with twins.

Let me know your thoughts...sorry for the long post, but I'm ready to pull the trigger on a twin kit and would like some feedback from you guys.

Thanks!
 

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It depends on what kind of classes you plan on racing. A lot of classes give better weight breaks to single turbo vs twin turbo cars. However, if you plan on just doing true street events, then the twin turbo won't hold you up from that.

Twin 66s can make GOBS of power. Using 6766s, my buddy got his convertible 4.6 car into the 5.0x @ 140ish mph in the 1/8 on an 8.5 tire, and around 3400 lbs. It shouldn't have an issue getting you to 8.50s in the quarter.
 

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Where will you mount the one large one vs the two small ones? If you mount them low you'll need a scavenge pump if you mount them high you wont.

It will cost more to go twins b/c you need two of everything and the piping doubles and the room to fit it all in there gets cut in half. Going twins means you have to find room to run two sets of piping and there may not be enough room or you will have to snake all the hoses/lines through the piping on both sides. If you run one turbo then you can run the one set of pipes on one side of the car and all the necessary lines/hoses, etc on the other side.

By the time I finished my custom twin install I wish I had one turbo to deal with BUT twins sure look a lot nicer than a single.

Overall I think twins will be the best for what you want to do, though.

ks
 

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Discussion Starter #4
It depends on what kind of classes you plan on racing. A lot of classes give better weight breaks to single turbo vs twin turbo cars. However, if you plan on just doing true street events, then the twin turbo won't hold you up from that.

Twin 66s can make GOBS of power. Using 6766s, my buddy got his convertible 4.6 car into the 5.0x @ 140ish mph in the 1/8 on an 8.5 tire, and around 3400 lbs. It shouldn't have an issue getting you to 8.50s in the quarter.
No class racing for me! Just good old fashioned bad Azz street car that hits the track about half a dozen times a year and frequents car shows. Thanks for your input!
 

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Discussion Starter #5
Where will you mount the one large one vs the two small ones? If you mount them low you'll need a scavenge pump if you mount them high you wont.

It will cost more to go twins b/c you need two of everything and the piping doubles and the room to fit it all in there gets cut in half. Going twins means you have to find room to run two sets of piping and there may not be enough room or you will have to snake all the hoses/lines through the piping on both sides. If you run one turbo then you can run the one set of pipes on one side of the car and all the necessary lines/hoses, etc on the other side.

By the time I finished my custom twin install I wish I had one turbo to deal with BUT twins sure look a lot nicer than a single.

Overall I think twins will be the best for what you want to do, though.

ks

All great points for sure! And I've considered them all. I'll be having my buddy Jeff at Pony Down build me the kit. He places the turbos high, so no oil pumps. And with the positioning of the 3" downpipes and wastegates, it actually fits nicer than a large monster single turbo...on my car at least.

I guess I've already convinced myself that I want twins, but I'm not sure what size turbos. I don't want the car to have more lag than my single, but I also don't want the turbos to choke up with higher rpm. I was going to run .68 exhaust housing on two 66mm turbos. I'd like the room to grow with a big bore 347 next year and maybe a tight lash solid roller cam to rev it some more...maybe 7200?
 

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I sold my YSI and went twins. Way easier to package then a big single. I didn't want to deal with a 4" or bigger downpipe and where to route it. So I had a custom kit fabbed with the twins down near the fog lights on my 88 GT. I have Oiless turbos from Comp so no dealing with any scavenge pumps or anything. I say go for it man, especially on a street car. The thing I like the most now is how quiet it is. Idles and sounds like an NA H/C/I 302.
 

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Yeah, my builder wants to do twins because he says it's simpler, but I already have(most of) a single kit waiting to go on. I'm gonna run the single, but may upgrade to twins whenever I get back to making good money. Just wanna get this damn thing done already!
I'd think twin 66's should easily reach your goals.
 

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I sold my YSI and went twins. Way easier to package then a big single. I didn't want to deal with a 4" or bigger downpipe and where to route it. So I had a custom kit fabbed with the twins down near the fog lights on my 88 GT. I have Oiless turbos from Comp so no dealing with any scavenge pumps or anything. I say go for it man, especially on a street car. The thing I like the most now is how quiet it is. Idles and sounds like an NA H/C/I 302.
I've heard a ton of negative about the oiless. Yours doing ok? No experience just what I've read!
I think twin 76s would rock......
 

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Discussion Starter #10
Well folks, I've settled on twin Turbonetics 6668 turbos...should be good for 1400+ horsepower. I'm guessing that once my I get my tune dialed in with the new twin set up, I should be solidly in the 8s with about 18 psi...which leaves me room to grow in the future with more cubes and/or more boost...25 psi? 30 psi? 100 psi?? >:)
 

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I think you will like it. I'm in the middle of going from a single kit to a twin kit in my Lightning. I'm more street than anything and the more I read about twins on the street and how much more streetable they are than a bigger single the decision was made. The kit I have was made by Pony down custom for our trucks. I'm running twin Comp billet 67's with .81 housings. I also switched out the stock blocked 383 for a 412 ci Dart Iron Eagle motor I just built. Should be done in a few weeks.
 

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I think you will like it. I'm in the middle of going from a single kit to a twin kit in my Lightning. I'm more street than anything and the more I read about twins on the street and how much more streetable they are than a bigger single the decision was made. The kit I have was made by Pony down custom for our trucks. I'm running twin Comp billet 67's with .81 housings. I also switched out the stock blocked 383 for a 412 ci Dart Iron Eagle motor I just built. Should be done in a few weeks.
.-------------------------------------
PREVENTATIVE VEHICLE MAINTENANCE
 

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Discussion Starter #15
A long overdue update...

My car just ran two 8.50s in a row a few weeks back at 18 psi through the tailpipes on 275 DR's! I'm real happy. Should I turn the boost up more and go for a 7 second pass? 0:)
 

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My car just ran two 8.50s in a row a few weeks back at 18 psi through the tailpipes on 275 DR's! I'm real happy. Should I turn the boost up more and go for a 7 second pass? 0:)
Now THATS an update!! That had to feel damn gooooood!
Huge Congrats!!


ks
 
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Discussion Starter #17
Thanks a bunch KEVIN$! It definitely feels great! The car is ridiculous! I love the rush!!! Now I need more cage and a chute, etc...the track officials weren't real happy! Haha!
 

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Thanks a bunch KEVIN$! It definitely feels great! The car is ridiculous! I love the rush!!! Now I need more cage and a chute, etc...the track officials weren't real happy! Haha!
A few more years and hopefully I'll get mine down the track..still stocking up on Depends undergarments.

Did you ever switch to E85 or do the flex fuel setup?

ks
 

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Discussion Starter #19
A few more years and hopefully I'll get mine down the track..still stocking up on Depends undergarments.

Did you ever switch to E85 or do the flex fuel setup?

ks
Hahaha! I hear ya on the Depends...I've wanted to let off before the end of the track a few times...down right scary fast on the top end!

I decided to just run C16...it's very reliable for my combo, and although it's expensive, it's readily available for me. I only drive my car to a few car shows here and there and take my wife for "terror rides" sometimes! The rest of the time it's a 1/4 mile at a time.

Hang in there man...I can't wait to see how your machine works out at the track for you!
 
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