11.0:1 Compression & Supercharger

[Tyler2386]

I am strongly considering the TVS style blower for my 2015 GT. However, I remember hearing people say that 10.0:1+ compression is no bueno for blowers unless you have a built bottom end. What gives?? Have there been improvements in design over the last decade that make it "safer" for cars with higher compression to make 550-600 with a blower (this is the range I have been told is "safe" for our motor)?

I have seen multiple examples of 11-14 cars that survived with the TVS and a good tune. Also, unless I am mistaken, Roush showroom cars have the same motor we have with their supercharger. Surely if this were a time bomb it would be a losing proposition for them since they warranty their work.

As always, your insights are appreciated!:cheers:

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[Tyler2386]

Tuners/Retailers (Beefcake, BBR, Hypermotive, Boostworks),

Would greatly appreciate your informed opinions on this topic. Hoping to get a lot (100k) out of my stock internals with moderate driving (occasional spirited driving, etc) and <600rwhp. Baring unfortunate occurrences like manufacturing defects, etc.

 

[dirty-max]

Subd

 

[JolleyRoger]

I am sure they will chime in, but the issue with the "static" CR is that as you cram more air into the chamber it increases the static CR based on how much air is pumped into the chamber and adding static CR and boost it becomes the effective CR (I think it is effective). This will increase the heat and cause detonation, which will be your real issue not so much the bottom end. This is why they use cooling in order to cool the charged air, the cool air will take less room the cylinder and will help to keep the fuel cooler to stop detonation from occurring.

Not that they are the same motor at all, but I had a 93 GT with a Vortech charger on it (no intercooler) and ran 5lbs of boost for 8 years with no issues at all. Actually it increased my MPG, well as long as my foot was out of it.

One thing to remember is you will need good fuel. Even the brand of fuel made a difference. Some might say that fuel such as ARCO is the same, but I would have detonation with a brand such as ARCO as opposed to Chevron.

 

[Jimdohc]

Yes, over the last decade there have been improvements. The biggest improvement is 4 valve combustion chamber design. Advancements in ECU technology help too.

 

[jayman33]

We've had no issues running boost on these motors, these higher compression motors don't require as much boost to make great power. We made 624rwhp/ 515TQ on our whippled 2011 running 10lbs of boost. Our 13 GT ran 651/550TQ on an 82mm pulley 10-11lbs of boost for 18k miles without a single issue. I could go on with the F/I applications we used on stock engines but those two come to mind.

Tune plays a huge and vital role in the overall health of the engine. I've always liked the TVS blower, IAT wise they're a cooler running positive displacement blower, very efficient as well. We've had great luck with them and they're very OEM like.

Hope this helps. I'm giving merely HP numbers as a gauge, HP numbers aren't everything but is a decent guideline. Any other questions let us know

 

[wproctor411]

Like Jay said it's all in the tune and from what I've read the cylinder heads keep the air flowing very well so good combustion chambers would likely help. If you want 100,000 miles it depends on how you drive it. Every engine will only spin X-number of RPMs before the bearings are wore out of spec.

 

[Tyler2386]

Thanks, guys. I appreciate the responses.

Jay - what kind of issues did your 2013 car develop after 18k miles?

 

[jayman33]

No issues at all, we sold it

 

[Sales@BBR]

The BIGGEST thing that helps with the higher compression and boost is the VCT to have more over-lap. You can move the timing around to relieve pressure in the cylinders with the tuning.

Now on HIGH boost applications (18+psi), we recommend a lower like 9 o 10.1 compression but then the block comes into factor on cracking.

 

[Nick@JDM]

I am strongly considering the TVS style blower for my 2015 GT. However, I remember hearing people say that 10.0:1+ compression is no bueno for blowers unless you have a built bottom end. What gives?? Have there been improvements in design over the last decade that make it "safer" for cars with higher compression to make 550-600 with a blower (this is the range I have been told is "safe" for our motor)?

I have seen multiple examples of 11-14 cars that survived with the TVS and a good tune. Also, unless I am mistaken, Roush showroom cars have the same motor we have with their supercharger. Surely if this were a time bomb it would be a losing proposition for them since they warranty their work.

As always, your insights are appreciated!:cheers:

It certainly isn't ideal to boost an 11:1 compression engine. You will not see a factory (Roush is not factory) supercharged Ford that high. The GT500 is 9.0:1.

That said, it does not mean that you can't do it. The key here is to keep boost around 10psi and run lower ignition timing. We don't go higher than 14 degrees typically but I have seen others run up to 18 degrees. I think they are nuts. Good quality fuel is also important. No pump gas is considered good quality fuel IMO and is the reason why conservative timing is important.

A common misconception about these motors is thinking that the knock sensors are your savior. If a knock sensors detects knock and start to pull timing it is already to late and some damage is already done. This is a reactive tuning solution and designed for naturally aspirated applications by Ford. You can get away with some knock on an N/A motor, but on a boosted motor the added heat and pressure is not as forgiving. A factory GT500 from 2007-2010 has no knock sensors active for that reason. 2011-2014 GT500s have sensors active but they are only able to pull 1 measly degree of spark and the sensitivity is so high you would have to hit the motor with a sledge hammer to set it off.

 

[Nick@JDM]

The BIGGEST thing that helps with the higher compression and boost is the VCT to have more over-lap. You can move the timing around to relieve pressure in the cylinders with the tuning.

Now on HIGH boost applications (18+psi), we recommend a lower like 9 o 10.1 compression but then the block comes into factor on cracking.

+1

 

[Tyler2386]

Very much appreciated, gentlemen.

 

[2c5s]

The BIGGEST thing that helps with the higher compression and boost is the VCT to have more over-lap. You can move the timing around to relieve pressure in the cylinders with the tuning.

Now on HIGH boost applications (18+psi), we recommend a lower like 9 o 10.1 compression but then the block comes into factor on cracking.

Well said. Also, see my sig for an example. She is still living making over 900 wheel at 11.5 to 1. Always worried about the block issue at that level though.

Now, my factory short block 2012 5.0 lived for a short while at 750 wheel, then it snapped a rod. My 2015 will be at 600 wheel as my dd. I'm good with that.

 

[Travis@boostworks]

Static compression (11:1) is less of an issue when you have the ability to control dynamic compression with variable cam timing.

By having complete control over valve timing events with 4 cams and cam phasing, you can change the dynamic (effective) compression. This allows us to change cylinder pressure, move peak tq around, promote scavenging, and for purposes that we're concerned with here, make big power on lower octane fuel.

In the end, we're still octane limited. However, the efficiency and flexibility given to us with variable cam timing allows us to make big power with less displacement.

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