DiMora's Build Thread

[DiMora]

A 9.8:1 compression engine, at 18 PSI has an effective compression ratio of 21.8

My 11.5:1 compression engine, at 13 PSI has an effective compression ratio of 21.67

In other words, using the above numbers, cylinder pressures should be nearly identical.

So...I think I can run this setup at a boost not to exceed about 13 or 14 PSI and be safe...at 13 PSI I'll be making the same cylinder pressures as someone running a 9.8:1 engine with 18 PSI of boost.

 

[Badd GT]

I think it has to do with the 4032 piston material the Mahle has. The higher silicone content in the 4032 makes the piston more brittle and less mallable. That coupled with pump gas makes it susceptible to detonation. I relate this to concrete because I know construction, concrete has great compressive strength but no tensile strength, that's why it cracks. I think the silicone content in the Mahle gives it the same qualities. Mahle flat out told me not to run boost with their piston. Mahle 888-255-1942

 

[thump_rrr]

I think it has to do with the 4032 piston material the Mahle has. The higher silicone content in the 4032 makes the piston more brittle and less mallable. That coupled with pump gas makes it susceptible to detonation. I relate this to concrete because I know construction, concrete has great compressive strength but no tensile strength, that's why it cracks. I think the silicone content in the Mahle gives it the same qualities. Mahle flat out told me not to run boost with their piston. Mahle 888-255-1942

That's funny coming from a company such as Mahle, known for being the OEM supplier of the pistons used in the Porsche 911 Turbo.

 

[Badd GT]

Mahle does make some pistons out of the 2618 material more suitable for boost/turbo these 3v pistons aren't. Wasn't worth the risk to me.

 

[eighty6gt]

New FRPP 5.3 designed to get hammered with boost has Mahle 4032 pistons. Also the 2013 GT500. Searched 4032 mahle, this guy ran 100,000 miles in his silverado.

"It ran different power levels throught its life with most of its time spent between 12-15 psi which would produce 7-800 flywheel hp. I had a valet switch on it that cut the boost to 5psi that I used when I towed my trailer or valet parked it. I would see 20psi once in awhile for fun on the streets and a couple times on Power Tour. It ran 11.4X on 19 psi at 5500 pounds at a Silverado SS meet here in Michigan around 2006-2007 I think, the engine was installed in 2002."

http://ls1tech.com/forums/forced-induction/1317176-107-000-boosted-miles-comes-end.html

 

[Badd GT]

your correct on that ford 5.3 Eighty6gt. I don't claim to be the expert just passing on what I learned in my engine build. Unless brenspeed changed they put the 2618 in the B-326, and with what Mahle and Lito told me led to my decision.

 

[Pentalab]

Check this out:

A 9.8:1 compression engine, at 18 PSI has an effective compression ratio of 21.8

My 11.5:1 compression engine, at 13 PSI has an effective compression ratio of 21.67

In other words, using the above numbers, cylinder pressures should be nearly identical.

So...I think I can run this setup at a boost not to exceed about 13 or 14 PSI and be safe...at 13 PSI I'll be making the same cylinder pressures as someone running a 9.8:1 engine with 18 PSI of boost.

## I see the FRPP aluminator can be had in either 9.5:1 CR, NA version...or 11:1 CR, blower version. Folks ( including roush) all use the 11:1 version..then use a blower. This is on the coyote eng.

The 2012+ ford focus uses 12:1 CR. Roush used just 8.5:1 CR on it's 540H + stage 3 cars + P51A/B etc.... + 15 psi boost. Roush was getting aprx 510 rwhp from it's 540h..with 281 ci + 15 psi.

These days folks are getting nearly 600 rwhp from the 11+ cars, with just a 82mm pulley, and 11:1 CR..and no where near 15 psi.

IMO, 11.5:1 or even 12:1 CR is ideal. 90% of the time the blower is not used, so the higher CR works good when in NA mode. Better to have 11:1 vs 8.5:1 CR.

In your example above, 11.5:1 vs 9.8:1..means 5 psi less boost required = less hp to run the blower, and a lot lower blower discharge temps ( pre-ic). Then just tweak the timing with the fuel used.

 

[DiMora]

I concur, Jimbo. That's what I calculated...5 PSI less to make the same power...and out of boost the engine will be more efficient like when cruising on the highway.

The pistons look very well made. Nice and thick between the top and first ring (ring land)...another member on here sent me this photo of the same pistons (his are .020 over, but you get the idea):

I talked to my tuner tonight and he said he has no problem with tuning my setup...so it looks like I will proceed with building the short-block as-is.

TSS billet oil pump gears arrived today:

My biggest challenge will be finding time to build this thing, as work is keeping me busy and we will be moving soon. You may not see much action from me in this thread for a few months...but I'll slowly keep collecting parts as I see good deals.

My tuner and I discussed running E85...I might just put her on the corn.

 

[swflastang05]

I concur, Jimbo. That's what I calculated...5 PSI less to make the same power...and out of boost the engine will be more efficient like when cruising on the highway.

The pistons look very well made. Nice and thick between the top and first ring (ring land)...another member on here sent me this photo of the same pistons (his are .020 over, but you get the idea):

I talked to my tuner tonight and he said he has no problem with tuning my setup...so it looks like I will proceed with building the short-block as-is.

TSS billet oil pump gears arrived today:

My biggest challenge will be finding time to build this thing, as work is keeping me busy and we will be moving soon. You may not see much action from me in this thread for a few months...but I'll slowly keep collecting parts as I see good deals.

My tuner and I discussed running E85...I might just put her on the corn.

Good deal, put her on the corn, you won't regret it! I love my e85.

 

[AutoXRacer]

Wish I could go corn.

 

[DiMora]

Mahle called back and told me these pistons are fine with boost. I told them 9-12 PSI is my target; they expressed fuel concerns beyond 9 PSI on pump gas, but running E85 would solve that issue.

 

[Badd GT]

e85 is a viable option,from what I understand. In and around Raleigh there is only 1 e85 station, and it is about 25 miles from my home so.......... not an option for me. Kind of messes up any kind of travel, or spontaneity I poked around on an e85 finder website and they (e85 stations) don't seem to be that plentiful. My shortblock wasn't together yet so it wasn't that inconvenient to change the pistons, and I didn't have to upgrade my fuel system for the e85

 

[AutoXRacer]

Mahle called back and told me these pistons are fine with boost. I told them 9-12 PSI is my target; they expressed fuel concerns beyond 9 PSI on pump gas, but running E85 would solve that issue.

Tell me more about what Mahle said about pump gas and 9psi.

I am now wondering if running 14 psi at 720wrhp is safe even though timing is highly conservative.

 

[swflastang05]

Wish I could go corn.

No stations in your area? They just opened a second one by me!

 

[AutoXRacer]

There is only one station locally... I like to do road trips in my car...so one E85 station won't do it for me... Lito is already talking about how we will lower the HP on the car. sigh

 

[swflastang05]

There is only one station locally... I like to do road trips in my car...so one E85 station won't do it for me... Lito is already talking about how we will lower the HP on the car. sigh

Yea that sucks! Well you can run e85 in town, then if on your trip there is no e85 you can always re-flash to a pump gas tune. That's my plan if ever needed.

 

[DiMora]

I spent the whole afternoon sipping coffee and searching for threads on all the forums where guys have shared their CR / Boost / Timing and fuel choices...I think I'm onto something.

If you are boosted, chime in here so I can firm-up my theory:

http://www.s197forum.com/forum/showthread.php?t=121142

Anyway, here is what I am thinking appears to be pretty standard trends:

• A target effective CR of 18.5:1 is just about right on a modular forged engine - regardless of power adder.
  
• A change of 1.0 units in compression ratio seems to equal the about a 3 PSI change in boost to maintain the same effective CR.
  
• 93 Octane tunes usually run about 17 degrees of timing
  
• E85 tunes usually run about 22-23 degrees of timing

Examples: 9.0:1 CR @ 15.5 PSI = Eff CR 18.49; 10.0:1 CR @ 12.5 PSI = Eff CR 18.5...you can see that is a 3 PSI difference.

Notes:

Effective Compression = ((Boost PSI / 14.7) + 1) * Current Static Compression Ratio
1 Bar = 14.5 PSI
1 Atmosphere = 14.7 PSI

Calculator here: http://www.gtsparkplugs.com/EffectiveCompressionCalc.html

So...I'm thinking that I should build this thing with the 11.5:1 compression, pulley it for 9 PSI and give it 17 degrees timing on 93 Octane...If I run E85 we simply bump the timing up to 23 degrees.

 

[05stroker]

I spent the whole afternoon sipping coffee and searching for threads on all the forums where guys have shared their CR / Boost / Timing and fuel choices...I think I'm onto something.

If you are boosted, chime in here so I can firm-up my theory:

http://www.s197forum.com/forum/showthread.php?t=121142

Anyway, here is what I am thinking appears to be pretty standard trends:

• A target effective CR of 18.5:1 is just about right on a modular forged engine - regardless of power adder.
  
• A change of 1.0 units in compression ratio seems to equal the about a 3 PSI change in boost to maintain the same effective CR.
  
• 93 Octane tunes usually run about 17 degrees of timing
  
• E85 tunes usually run about 22-23 degrees of timing

Examples: 9.0:1 CR @ 15.5 PSI = Eff CR 18.49; 10.0:1 CR @ 12.5 PSI = Eff CR 18.5...you can see that is a 3 PSI difference.

Notes:

Effective Compression = ((Boost PSI / 14.7) + 1) * Current Static Compression Ratio
1 Bar = 14.5 PSI
1 Atmosphere = 14.7 PSI

Calculator here: http://www.gtsparkplugs.com/EffectiveCompressionCalc.html

So...I'm thinking that I should build this thing with the 11.5:1 compression, pulley it for 9 PSI and give it 17 degrees timing on 93 Octane...If I run E85 we simply bump the timing up to 23 degrees.

Sounds about right. Mine is 29.96 at 22 psi and 12:1 and would be the same as 9:1 and 33 psi. Lol

 

[DiMora]

Sounds about right. Mine is 29.96 at 22 psi and 12:1 and would be the same as 9:1 and 33 psi. Lol

That's awesome. I could go look, but what's the rest of your setup as far as power adder, timing, and fuel are concerned?

 

[DiMora]

Tell me more about what Mahle said about pump gas and 9psi.

I am now wondering if running 14 psi at 720wrhp is safe even though timing is highly conservative.

They left me a voice-mail. I typed this as I played it...they said:

"On the M142 alloy...9 pounds of boost would be no issue, we have guys running up to 15 on that. Now the issue is the 11.5:1 with the 9 pounds of boost on gasoline...we do not recommend that high compression with that boost level...now if you're running alcohol, guys have been getting by with it on alcohol. Not sure what type of fuel you are using, bu the M142 alloy is definitely a good alloy - SuperCobraJets run that allow on all the parts we make for those guys and they are having good consistence with that."

I think that is a good, conservative approach for a manufacturer to take...and I may well just put this build on the corn...but the more I study this, the more I think I'll be fine with 93 octane and reasonable timing of 17 degrees or so maximum. My tuner can keep my knock sensors enabled, and I also have a Snow Performance Stage 3 meth system on the car I can leverage...maybe I'll buy the safe-injection module that dumps boost (opens bypass valve) if meth flow is not detected.