Comp ratio

turbovenom

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Hey guys just picked up a twin turbo kit and after debate I decided I'm going to put some internals in it. I haven't bought any yet my question is what compression to go with? A semi local tuner said 11:1 mmr suggested 10:1 my built cobra was like 9:1 so both of those were surprises to me. Anyways first gen street car (daily) with some track use. My fuel here is only 91 and I'll have a separate tune for e85 or 110 etc. Any thoughts or experiences on the coyote platform?

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Zemedici

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Who's going to tune it?
Should get with them, for their recommendations. But cant get too rowdy if you're wanting to run pump gas in it
 

turbovenom

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Not sure yet I'm kinda leaning towards a Lund tune as I'm not sure who does a good job here I'm in AZ. It will be 91 for the most part so highest would prob be 11:1 but I guess I'm old school thinking as my cobra was 9:1 for big boost but from what I see the coyote guys arent running low comp I'm just not sure if say 10:1 is not enough umph for the turbos or what

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slow306stang

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Who's going to tune it?
Should get with them, for their recommendations. But cant get too rowdy if you're wanting to run pump gas in it
I agree that pump gas is the main limiting factor. You'll want to keep it at about 700whp on pump with 11:1 compression. The lower the compression goes the higher the tuning window goes. That will allow you to make more power on pump gas but you're going to rely on more boost to get there.

When it comes to e85 the sky is the limit. I'm running 12:1 compression with 32psi of boost.
 

biminiLX

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What are you building? I’m assuming Coyote?
Who's going to tune it?
Should get with them, for their recommendations. But cant get too rowdy if you're wanting to run pump gas in it
This. I’d assume you could have some local options that are solid but if not I think Lund Racing is a great mail order option.
Do you still have E50 in AZ? I’d rather run and build it for E50 that is consistent over 91 pump.
-J
 

turbovenom

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Also I can be around the 7 mark and I understand the value of throwing internals in it that aren't maxed out but I really wanted to up the power by doing so not to stay the same level. I guess now I'm thinking maybe roll with what I have. Also I have been told different things by different people on the vct, keep or lock it out? What are the advantages and cons? Ill start with Emissions are not a concern and for now planning on stock cams.

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biminiLX

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My friend just made 1300rwhp and still has VCT. That’s extreme and tightly limited on the vct but still possible. If it’s a street car and the majority of your driving isn’t WOT, you probably want to keep the stock VCT.
For builds over 1000hp, probably want to lock the cams.
Who is your tuner?
-J
 

Deceptive

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My understanding is this, as long as rings are gapped properly you are going to be at the same power limit whether you get a 9:1 or 12:1 CR engine. Your fuel is going to limit you.

The car should be overall faster with 11:1 or 12:1 than 9 or 10:1 as off boost performance will be better.

You probably should have talked to somebody before you bought the kit.


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turbovenom

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Why would I have "talked" to anyone before buying the kit? The turbos are sized appropriately and i could use the kit as is.I am just reaching out to see what others have found work the best for my particular case. I'm sorry but responses like that are not helpful.

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biminiLX

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With 91 being your primary fuel I wouldn’t want more than 10:1 however with the Coyote and their VCT they seem to roll out well with the stock 11:1 even boosted.
Best to commit to Lund and have them help you spec it.
-J
 

turbovenom

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I wrote Lund maybe they were busy but very short and not really helpful so far they do respond quick but not detailed almost like i was bugging by asking and things like he said i might need a bigger intercooler to hit my levels which would be good info had he known what my setup wven was or which intercooler i even have. but I've heard good things about them i just want someone i can trust and they didn't seem like they wanted to be bothered.cFrom what I understand the rods are the weak part here i called mmr they said stock crank is good to 2khp that seemed extremely high to me, can anyone chime in on that? Should I just do rods n pistons instead of a rotating assembly?

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MG0h3

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Isn’t your car already 11:1 from the factory?

Properly tuned, I don’t think you can reach the limits of the stock longblock in any coyote on 91.

Doesn’t matter if it’s 8:1 and 20psi or 11:1 and 8 psi.

Pretty sure guys push those things up to around 800 wheel on E and you really aren’t going to do that on 91 so I wouldn’t sweat building a longblock.


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turbovenom

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Yea, I'd like to run a e tune though and my motor is out now so I was thinking about doing it. A tuner I had talked to told me pushing a first gen if it detonates at all it won't matter if knock sensors try to correct it will be enough to break the factory rods. Now I'm not using that tuner because I've heard they aren't the best but it did put a bug in my head and is why I'm thinking about it. 800 with e doesn't seem to high what are guys doing to get around 1k mark are plus valves and cams a must to achieve theese levels or??? I'd like to run 91 but also want to turn it way up on e or a race fuel at the track the rest of the car is ready for power I have more than enough fuel clutch is good for at least 1200 etc so that's where I'm at is a rod that is questionable I might just roll with it but then I will be pretty passed I didn't if I grenade it.

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Deceptive

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Why would I have "talked" to anyone before buying the kit? The turbos are sized appropriately and i could use the kit as is.I am just reaching out to see what others have found work the best for my particular case. I'm sorry but responses like that are not helpful.

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Regardless of what internals you have the limiting factor is going to be fuel. Regardless of what CR you have, you are still going to be limited by fuel. On 91, a good and knowledgeable tuner will probably not want to go much over 650hp or so regardless of you having a 9:1 or 12:1 CR. That is why you should have talked to somebody first.

The higher your CR the better the car will feel on 91 because it will make more power on lower boost and make more power out of boost.



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turbovenom

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I guess I'm just not understanding what your saying by I should have talked to somebody first for? Nothing on the turbo kit side of things would change and I am trying to talk to somebody now on best engine setup. The car will more than likely be sitting 6-700ish normally but like I said and the only point to go nuts on the motor is because while 91 will be my primary fuel it will not be the only fuel. I want to be able to turn it way up if need be I can get e85 or race fuels in 55gallon drums at a min but where the tracks are here I can get it there to but it's a couple hours away so I can use them at will but it's not practical all the time. The car is well setup to handle 1000rwhp (fuel,clutch,trans,etc) just need motor built and I'd like to get to around 1000 or as close as i can. I really will take your input but I'm confused if I said I bought a 105mm single kit I think I'd understand that I should have talked to someone first as that wouldn't really be a good setup for my use case.

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