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Hey guys,

Currently running a gtx3067 20psi 350whp and about 50% duty on pump fuel id1000cc stock fpr, walboro 255

Looking to run e85 and nitrous with possibly a larger turbo - Gtx3582 twin scroll on e85 and nitrous - 30psi. Going to a walboro 400 - what size injectors do you think a good size , not too big / small with good idle capacity.

Also. If changing a turbo - at the same boost pressure with a larger turbo, will this produce more power / torque . What is the concept behind this ?

Ie - two turbos with identical exhaust turbines but different compressor wheels - 67mm vs 82mm both @ 20psi, why would or wouldn't the larger one be better etc.
 

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Damn youre dedicated to this set up.

Injector dynamics. Probably 1000cc+ You could probably do it with a -6AN feed as well.

But know, you can raise fuel pressure up to 150psi on those injectors and push a hell of a lot more cc than rated at.

As far as the turbo compressor questions, I believe its a matter of efficiency is all. That being said, Im not sure how 20psi intake manifold can be different than another intake manifold at 20psi. Its my impression boost is the measure of air backed against the intake valve. If you can move more air into the cylinder, you will make the more hp with less boost because the same amount of air moves through easier. Hope it helps a little
 

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What are you typing to accomplish with all the changes? You trying to use the nawz to help spool a larger turbo?
 

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95 civic coupe
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I am using 1000cc and running out of injectors at around 420ish with E85 and 255 pump. So with that said, you might want to look into 1600 at the very least so you have a bit more room to grow. Sounds like a very fun set-up though, our buddy Todd have broke to 9s on a d16 with that Gtx35 turbo
 

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Damn youre dedicated to this set up.

Injector dynamics. Probably 1000cc+ You could probably do it with a -6AN feed as well.

But know, you can raise fuel pressure up to 150psi on those injectors and push a hell of a lot more cc than rated at.

As far as the turbo compressor questions, I believe its a matter of efficiency is all. That being said, Im not sure how 20psi intake manifold can be different than another intake manifold at 20psi. Its my impression boost is the measure of air backed against the intake valve. If you can move more air into the cylinder, you will make the more hp with less boost because the same amount of air moves through easier. Hope it helps a little
With regards to the efficiency of a compressor, a larger compressor could in theory possibly flow more cfm while also at a higher psi and while doing this, be in a higher efficiency island. If he was originally at 65% compressor efficiency (at peak boost/rpm) with the old compressor and is now at 75% at peak boost/rpm, he could definitely be making more power, as that is less turbine back pressure (turbine back pressure= exhaust back pressure= more pumping losses and less room for more chair air= less power) being wasted as a heat by product. Further more the higher efficiency would also result in a lower air charge temperature, allowing a more aggressive tune and taking in more oxygen (cooler air= more dense= more oxygen), all this results in more hp with the same boost psi.

For the answer, learn how to read compressor maps, do the math and see if it would prove beneficial. (does efficiency improve at desired hp target/ rpm).
 

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You need to plan out how much lb/hr you need to flow through that engine to make peak power and then graph out how much is going to be going in and exhausted to find what your needed sizes are. making the compressor side larger but not changing the exhaust turbine size creates a restriction. Your pumping more air into the engine, yet not allowing it to exit faster, this causes backpressure problems and lowers your exhaust pressure to boost pressure ratio.

Going a little too large on the exhaust is better than restricting it as you will take longer to spool but will have a free flowing exhaust path, going too small causes loss of power but also causes boost creep and focuses heat in the volute and turbine wheel causing high temperatures.

As far as injectors go, last time i saw a post on someone running RC1000's they were on the edge of a "nice" idle on e85. cannot imagine 1600+ would idle very nice at all. At this point you may be very well suited to an aftermarket ecu to handle the larger injectors on a much higher resolution. unless you start mixing more gas in with the e85 so you do not have to inject as much. Perhaps even meth injection with a splash of e85 in the tank instead.
 

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How many people on here keep track of compressor RPM or Turbine back Pressure.

What is it like, ~2:1 exhaust pressure will result in failure to create viable power.
 

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How many people on here keep track of compressor RPM or Turbine back Pressure.

What is it like, ~2:1 exhaust pressure will result in failure to create viable power.
I think the last gt35 i was looking at had a exhaust to pressure ratio of 1:1.2 at best. I dont really see the need to track turbine rpm but back pressure would be good to see if you have a restriction or could get away with a smaller exhaust housing.
 

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If you know what fuel you want to use and how much power you want make, use a fueling calculator to properly size the injectors.

There are many out there on the Interwebs, and we have one on my company's site:

Fuel Injector Calculator | Fuel Calculators | Resources | DeatschWerks


For sizing injectors, I would recommend using 80-85% duty cycle to ensure you have enough headroom.
 

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The figure was from Maximum Boost, I think it was a generalization to point out high exhaust back pressure is bad. Im not sure if we are even speaking in the same terms. I believe it was something vague and big picture like Exhaust Manifold to Intake Manifold pressures.

Dan the 10 second moderator, said something like, Big Exhaust Housings make you go fast. So maybe .86 AR time?

Pressure varies on both sides of the turbo, as do leaks, and efficiency changes with RPM, on and on. Cant nerd it out or youll ruin the fun though. Just use your best intuition OP and pick one. If there was an answer, we wouldnt be racing anymore. Its a game.
 

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You'll need a different FPR anyways with the wally 450, so why not just increase fuel pressure?

Jumping up to 70psi would get you 30% more fuel. With E85 you'd be back at ~50% at your current 350whp. If you do get something bigger, I'd suggest you look at the new 1600's. They're crazy-expensive from ID, but much better priced from other vendors. They also have none of the flow change (swelling seals) from hot fuel or exotic fuels that ID2000's have.
 
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