Twin Turbo Install Need Some Advice

Apr 24, 2014
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Hey guy so i have a complete twin turbo kit, still in the process of installing it right now. Just want to go over some things to get a complete rundown on everything that is going to be done. So currently the motor is rebuilt, all new bearing and forged interals in an 89 block. Gt40p heads, gt40 intake, tfs valve spring, 1.6roller rockers, afm n-41 camshaft, flat top pistons. Nothing has been notched or ported. I have a complete twin turbo kit im currently installing on my guinea pig 302. It is my first build and want to understand how it all works to build a solid 408 stroker. So im assuming that i am around 9 or 9.5:1 compression. My question is how much boost can i use safely and reliably on the motor, i also have easy access to a gas station that sells 100 octane which I don't mind running
 
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a91what

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Boost timing compression

Pick 2.....

Water methonal will be your friend.

I would say 6psi (nothing for a tt setup) with 23* total timing on 93 octane. As the boost goes up timing cuts drastically, by 10psi 20* or less.

The tuner will make these decisions as far as timing retard.
 
Apr 24, 2014
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In the forums ive read, if i run a higher octance i can run more boost correct? Some people say otherwise, i currently have 30lb injectors on the motor, and i will upsize them if needed. Im really wondering if its posible to run 12-15psi on it and not detonate the motor, im alright with running the 100 octane from the 76 down the street, am i dumb? Haha, just have a feeling i might get greedy and want more then 6psi
 

a91what

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In the forums ive read, if i run a higher octance i can run more boost correct? Some people say otherwise, i currently have 30lb injectors on the motor, and i will upsize them if needed. Im really wondering if its posible to run 12-15psi on it and not detonate the motor, im alright with running the 100 octane from the 76 down the street, am i dumb? Haha, just have a feeling i might get greedy and want more then 6psi
I have tuned many sbf engines... each combo takes something a little different. With your setup I would run no more than 10psi on 93 octane. Water meth will let you run more however a stock block has it's limits.
 

FastDriver

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With compression of 9:1, I personally think you'll end up with closer to 15 psi on pump gas without detonation, assuming 93 octane, an efficient turbo for your setup, and intercooled. That said, it's kind of a silly question. You don't find out what a motor wants by asking forum members. You find out by carefully tuning the combination first then dialing back on timing, cranking up the boost and then adding timing back in until the car isn't making power. Afterwards, you should probably back off of the ragged edge by a couple degrees of timing to avoid detonation under variable conditions (fuel, weather, etc...) Any other way involves unnecessary risk.

With race gas, as you mentioned, you'd definitely be able to add more boost than that.

Oh by the way, you will probably hit other limits, like your fuel system, or the block's strength before you run out of boost from the turbo or hit detonation on race gas.
 
Apr 24, 2014
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With compression of 9:1, I personally think you'll end up with closer to 15 psi on pump gas without detonation, assuming 93 octane, an efficient turbo for your setup, and intercooled. That said, it's kind of a silly question. You don't find out what a motor wants by asking forum members. You find out by carefully tuning the combination first then dialing back on timing, cranking up the boost and then adding timing back in until the car isn't making power. Afterwards, you should probably back off of the ragged edge by a couple degrees of timing to avoid detonation under variable conditions (fuel, weather, etc...) Any other way involves unnecessary risk.

With race gas, as you mentioned, you'd definitely be able to add more boost than that.

Oh by the way, you will probably hit other limits, like your fuel system, or the block's strength before you run out of boost from the turbo or hit detonation on race gas.

Definitely will take that into account man and will be asking for help if needed later this week, ran into a question today during some installation of it and cant find a answer to it, online. how do i hook a maf sensor up to the twin turbos? Do I need to buy something different? Totally lost here, over my head here with inexperience. Wire it in series? What is the most efficient way?
 

FastDriver

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That's outside of my lane. I'm using a speed density setup.

That said, my old incon twin turbo kit ran the MAF after the intercooler and before the throttle body in basically the same location as stock. The pipe for the MAF on the incons was pretty wide and long. I think that helped stabilize the air flow.

I believe the "blow-through" MAF setup is more common and less likely to peg the meter than the "draw-through" kind. However, it might be harder to tune. I did a quick google search and came up with these links. I'd recommend doing some more research to determine what's best for your application.
http://www.lasotaracing.com/techdrawthroug.html
http://forums.corral.net/forums/turbochargers/1197621-blow-through-vs-draw-through.html
 

a91what

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YES. When using a maf on a turbo setup it needs to be between the intercooler and throttle body. A good choice would be a newer slot style maf they tend to have better characteristics for this type of setup.
 
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Apr 24, 2014
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YES. When using a maf on a turbo setup it needs to be between the intercooler and throttle body. A good choice would be a newer slot style maf they tend to have better characteristics for this type of setup.
Awesome now the slot style works the same? Also i have 30lb injectors, should i scratch them and go to 42lb injectors?
 

a91what

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42lbers are pretty standard I would do some research for yourself. Look at injector sizing charts do some Google work.

The slot MAF is standard on newer vehicles, it will be wired into the harness with a new plug end. The ecu will need to be chipped to make this work.

Time to do some research look up these things and post what you find we will go from there, if you just take whatever advice is spoon fed to you eventually you will get some that is wrong.
 
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Noobz347

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I'm not sure that the majority of the questions asked are applicable. The block will never stand for any tune that makes 100 octane necessary. You will have two very nice 4 hole planters for your window sill.
 
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331turbo

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Iv ran a few twin turbo set up. I agree I don't think you'll be able to go over 10 psi with the 9:5:1 ratio. I'm assuming your running a intercooler. Also depending on where you live. Is it somewhere it is hot year round or not. Personal I'd put it on a dyno an slow tune the boost up an watch the air fuel. Anything over 500 is a ticking time bomb an stock black anyway.
 
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Apr 24, 2014
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Next question for ya guys...now that im boosted is this going to affect my vacuum lines like my map sensor, my brakes etc? If so i can go to a electric vacuum pump but i dont think that would work for the map sensor. Im having a hard time finding info on this
 
Apr 24, 2014
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Next question for ya guys...now that im boosted is this going to affect my vacuum lines like my map sensor, my brakes etc? If so i can go to a electric vacuum pump but i dont think that would work for the map sensor. Im having a hard time finding info on this
 

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Next question for ya guys...now that im boosted is this going to affect my vacuum lines like my map sensor, my brakes etc? If so i can go to a electric vacuum pump but i dont think that would work for the map sensor. Im having a hard time finding info on this
The MAP sensor does not connect to the intake manifold on a car that uses a MAF. Instead, the MAP sensor is a Baro sensor; either vent it to open air or connect it to a port in the tubing between the MAF and throttle body.
 
Apr 24, 2014
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My car stock had the map sensor connected to the intake?? And it ran great? Whats the benefit of plumbing it before the TB? And will the stock one work for this application? Ifound info on the brakes how an additional vaccuum canister and check valve will make them work. Another serious question is the pcv. Can it be vented to the atmosphere and just plug where it goes into the Intake? What would be the proper way to do that?