And Penny just keeps on changing... - Lateral-g Forums

Vegas69 · #1 02-17-2010, 08:40 PM

I bet it makes North of 700hp and 640-650lbft easy. Why a 114lsa with 11.5:1?

**Steve1968LS2** · #2 02-17-2010, 09:20 PM

Quote:

Originally Posted by Vegas69

I bet it makes North of 700hp and 640-650lbft easy. Why a 114lsa with 11.5:1?

I was leaning toward 112 LSA, but Craig over at COMP thought idle quality would suffer and the additional overlap would make the whole deal less street friendly. He did think it would generate more low and mid-range power though.

In the end I'm going to end up with more power than I really need so I erred on the side of idle and drivability.

For compression I was really shooting for 11.1 or 11.2 to one, but this is how it's working out with the pistons and the 72cc Mast heads. We might adjust it down a touch with the head gasket, but 11.5:1 isn't high, even for out crappy CA pump gas.

Horace at Mast was thinking it would be pushing 700hp.. now I just need to be able to hook it up. Also, while 700 is a good "magazine number" I would be happy with 650-670hp and a bad ass super flat torque curve.

Vegas69 · #3 02-17-2010, 09:33 PM

I agree, we are both pushing our chassis's to the max. I felt like my 491/497 at the tires was really managable across the board. I have similar expectations. 650-675hp and 625 ftlbs. Your making a vast improvment in your low end torque with identical stroke to me. I was able to hook up that 497 at 3800 with R888's in second gear matted during autocross. I felt it was about the limit however. A little loose but biting hard. On 200 tread wear tires I'm not to sure. You're going to gain some pull out of those slow corners and I'm going to gain 500-700 rpm to avoid shifting into 3rd until 85 or so. We'll put all that power to use on the road course for sure.

Crazy you can run 11.5:1 on a 114 with 91 octane. Do you run a knock sensor? I'd error on the side caution. Compression doesn't gain that much power.

**GregWeld** · #4 02-17-2010, 09:43 PM

Everyone I've talked to has said you can run up to a full point MORE compression on an EFI motor... over a carb.

Factory boys are running 12:1's and getting away with it...

Vegas69 · #5 02-17-2010, 09:56 PM

Really just trying to educate myself more on the LSX builds. I know aluminum heads allow about a point more but my point was, is the knock sensor retarding timing to much if you push the limit? Why does EFI allow that much more compression?

**GregWeld** · #6 02-17-2010, 10:06 PM

Hopefully Steve jumps in here and tells us what the motorheads think...

But I've always been told that aluminum heads are good for about a point - and EFI is good for another one... and of course all of this is "STATIC" compression because the real number that nobody mentions is CYLINDER PRESSURE... and that is controlled (somewhat) by the cam...

Vegas69 · #7 02-17-2010, 10:14 PM

Without hijacking Steve's thread, a 114 will build more cylinder pressure than a 112 or 110. I imagine it's ok due to a pretty radical camshaft for a LSX. Steve will fill us in...

Bow Tie 67 · #8 02-22-2010, 06:21 AM

Quote:

Originally Posted by Vegas69

Really just trying to educate myself more on the LSX builds. I know aluminum heads allow about a point more but my point was, is the knock sensor retarding timing to much if you push the limit? Why does EFI allow that much more compression?

Precise fuel controll when tuned correctly.

**GregWeld** · #9 02-22-2010, 08:15 AM

Quote:

Originally Posted by Bow Tie 67

Precise fuel controll when tuned correctly.

I don't want to jack Steves thread -- but this whole "compression" and fuel management thing brings up some thoughts about the LSx motors....

I'm a pyro.... and as such understand a bit about "compressing" explosive chemicals...

I think that we all know "more" compression is a problem and that for the problems it creates - the power increase is actually minimal... Which got me thinking about why the factory LS motors use what we used to think was an unworkable compression ratio on todays pump gas...

But they seem to make great power - AND use LESS fuel to do it - and they're using leaner mixtures (except at WOT). So when you compress LESS fuel/air - you get a little more "bang" for your buck... So.... I'm thinking they're on to something here.... (and they employ built in safeguards). You take less fuel - atomize it really well - get more flow into the cylinder with better heads - then you compress the hell out of it... and you're making some power while sipping gas. The gas sipping is partly due to the leaner A/F they can run (coming back to the EFI issue)... The control with knock sensors... AND let's not forget the 6 speeds and tall gears... (low rpms per mile). BUT you have power when you want it because of great heads - and high compression ratios... then toss in some 12:5 AF at WOT....

Just thinking out loud here....