5.0 Boost Compression

[JPO8GT]

I am noticing now that I'm looking at forged short block options that many boosted builds are staying 11:1 CR even seen some running 11.5:1 boosted instead of the old trend of running 8.5 - 9.5:1 or so on boosted applications.
I'm in the planning stage of my boosted coyote build so I'm deciding on the CR.
I am curious if any durability increase would be seen if I were to tick the CR back to 10.5:1 I don't want to run under 10:1 due to i want a more instant throttle response. So is the accepted norm of boosted compression on the new engine higher for a reason if so what makes it more acceptable than it was on 3 valves?
Every tuner i knew previously freaked out at the thought of running higher compression with boost especially on 93 pump street/strip now it's accepted by builders and tuners?

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[JoshK]

What kind of FI are you running. I am running an 11:1 3V engine

 

[JPO8GT]

Currently have a novi 2200 head unit that i previously ran on 9.5:1 3 valve.
I am considering installing it on my new coyote but I'm very tempted and prefer to go ahead and do the JPC single turbo kit on my new car.

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[BruceH]

I've run up to 19psi on a 3v with 10.76:1. IMO it was verboten in the past because because in the old days it would blow up a motor. Sometimes old thoughts are hard to kill off even when modern engineering disagrees.

Modern motors are stronger, better designed, and have excellent engine management systems. The fuel is also better. 10% ethanol is giving an anti knock cooling effect that can't be measured in octane. I believe that in part what we can do is because of ethanol in the fuel, not despite it.

As more people push the edge and don't have a catastrophic failure the old thoughts start to die.

More compression increases cylinder pressure which is what boost does. With more compression the cylinder pressure is higher with less boost. That means less hp taken up by a supercharger and imo that means less stress on the rest of the motor.

It's a great time to have a modified car. We have stock Mustangs that are running in the 12's and getting good mpg along with driveability. It's never been this good before. IMO we are in the golden age of musclecars.

 

[JPO8GT]

Makes sense to me Bruce there's to many having success with higher compression on these motors with the a centrifugal and a turbo both benefit greatly with the higher cr (less lag) i guess if i was going to run a pd blower then i may should consider a lower cr especially one that was setup for high boost and due to there instant full boost response hard TQ hit.
I'm thinking a properly built 11:1 with the considered power adders is going to be really good. Hummm11:5.1 and make up for the added weight of the forged rotating assembly and that heavy circle D converter haha easy to get greedy!

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[Grabber Blue 5.0]

I like the idea of running as much compression as possible nowadays for the same reasons Bruce stated. Plus more compression means you don't need as much boost. I would have no problem running a 11:1 motor with boost.

 

[Sonicblue_s197]

If I were you I'd run 11.0:1 , if you have e85 available I'd jump up a little, I wish I had gone higher but this was my first build and a couple e85 stations shut down so I chickened out and went 10.0:1, after I built my motor a new station opened up right next to my house fml lol next build Il be goin with a 11.5:1 with a turbo setup

 

[JPO8GT]

The power bugs are chewing on me again!! I have a really BIG TRIGGER I am debating on pulling! its killing me!!!! not to pull this trigger! especially when I went from a nearly 800 RWHP 93 pump/meth 3 valve 900 Rwhp on C16 now I'm in a stock new 5.0 coyote and I feel like I'm hitting the brakes instead of throttle in comparison to my built 3 valve,, I keep lying to myself saying I'm going to stay NA a while or a year!!! IM NOT GOING TO LAST LONG ITS KILLING ME!!!!

 

[JPO8GT]

As of today this 2014 5.0 Coyote stock short block is on the market 876 miles on odometer. A very built bottom & top end will replace her I give a toast to her she will serve someone greatly. Cheers..

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[JPO8GT]

Plans for built long block in worx..

 

[JPO8GT]

Built JPC/RGR Coyote shortblock with RGR Support System, Custom Diamond Pistons Double diamond coated, Oliver I-Beams and the works ordered from Eric @ JPC today!
Starting with a solid motor then wezz add boost...

 

[Mystickeith50]

Wow nice man.

 

[JPO8GT]

I decided to do things in opposite order that i did my 3 valve boosted it first blew it up holes in block damaged heads etc.
This one will get a built motor first..

 

[Mystickeith50]

What f/I u going with.

 

[JPO8GT]

JPC Turbo setup

 

[Full_Tilt]

We are long past the days of shitting tunning and poorly designed combustion chambers. You can throw a lot of boost at 11.0:1 CR with a well-tuned, modern engine. Ive seen s2000s make 600+hp on pump, with the stock block (which is 11.0:1).

The VVT on the coyote just makes it all the easier because you can retard the intake cams in the places were the engine would tend to detonate under boost.

Its the same story for NA engines. Ive seen street motors on 93 octane running 14:1 CR all day with no problems. Shits just getting better.

 

[onebadgsx]

Im getting ready for my f/i 5.0 build. I was looking at 10.5:1. Im going with e85 so wondering now if i should stick with 11.5:1

 

[Full_Tilt]

If youre going with E85 you should go with the 11.5:1. You probably wont be able to throw enough boost at it even at that "high" compression, unless you have some really fancy turbo(s).

 

[JPO8GT]

The only thing in my area e-85 is non existent closest station is 50 miles from home so i have to run Shell 93 octane i could run meth to help. But with turbo should still be able to run 11:1 and we're looking into 11.5:1..
I have plans to have a race tune done for VP EXTREME UNLEADED Race gas and then i can crank the boost up for max powaa

 

[JPO8GT]

Im getting ready for my f/i 5.0 build. I was looking at 10.5:1. Im going with e85 so wondering now if i should stick with 11.5:1

What fi? If i were running a PD blower id consider 10:1 especially if i we're going to over drive it for max power. 10.5:1 is a good cr for any of them centri or turbo probably would work ok on PD to but PD tends to heat soak when pushed hard.