Higher compression pistons? - Dodge Cummins Diesel Forum
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post #1 of 9 (permalink) Old 01-12-2009, 12:04 AM Thread Starter
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Higher compression pistons?

I've ridden in my cousin's 2001 HO with the 6 speed and it seems to have a lot more low end torque than my SO. I've been reading and it seems as though the difference comes mostly from its 17:1 compression ratio vs my 16.3:1 ratio. I also noticed that the 2nd gen 12v's make more low end torque than the SO cummins especially when you turn them up just a little bit. They had a 17.5:1 compression ratio. SO... I'm wondering if anyone makes a higher compression piston. I don't race this pickup, I just tow really heavy pretty often and I'm sick of the lack of low end power. It seems like I have to pass 2000 rpm's to really make good power with my engine. Any help or advice is appreciated.


'99 dodge 4x4 NV4500, Super X VP, FASS 150, Custom Quick Spool Super B w/ ATS manifold, RV's, Smarty programming. north of 400 hp... Bout to add water/meth injection
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post #2 of 9 (permalink) Old 01-12-2009, 08:50 AM
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What has been modified about the Super B? I'd guess what you are feeling is turbo lag. I felt the exact same thing when we switched out the HX-35 for the A3000.

- Mine: '09 GMC Sierra LTX ECSB 2WD - Deletes, 4" Exhaust, AEM CAI, DP LMM 2.6 Stg 1.5 Drag Turbo, BD Manifold, Diamond Eye Downpipe, All Season Diesel Performance EGR/Grid Heater delete, PPE Race Valve, Edge Insight, '08 Hummer Wheels, DSP5 - EFI Live tuning by Mark Broviak @ Danville Performance.
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post #3 of 9 (permalink) Old 01-12-2009, 11:07 AM Thread Starter
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Well I first bought a regular super B turbo from Farmboys but I felt that it was still a little bit too laggy for my liking so I called up BD power and had them machine me a smaller turbine housing that made it spool even quicker. Don't get me wrong, my turbo spools pretty dang quick now, but it still just seems like I'm lacking in low end torque.

'99 dodge 4x4 NV4500, Super X VP, FASS 150, Custom Quick Spool Super B w/ ATS manifold, RV's, Smarty programming. north of 400 hp... Bout to add water/meth injection
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post #4 of 9 (permalink) Old 01-12-2009, 11:34 AM
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What gears does your cousin's 6 speed have? 4.10s maybe? That would make it feel torquey.

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2000 QCSB, 180 pump, 6x.013's, maxspool 2.5, s364/s480, tranmission built by me, AD150

11.23 @ 121mph
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post #5 of 9 (permalink) Old 01-12-2009, 11:36 AM Thread Starter
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No, it's got 3.55's just like mine.

'99 dodge 4x4 NV4500, Super X VP, FASS 150, Custom Quick Spool Super B w/ ATS manifold, RV's, Smarty programming. north of 400 hp... Bout to add water/meth injection
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post #6 of 9 (permalink) Old 01-12-2009, 11:45 AM Thread Starter
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I'm curious as to why the first gen Cummins 12v makes 400 lb/ft torque and 160 hp. If you were to divide torque by hp, you'd get (400/160)= 2.5. So we can make up our own torque "factor" of 2.5. The 96-98 specs make 215/440 which would be (440/215) = 2.05. The 24v 99's made 235/460 which would be (460/235) = 1.95. The HO's made 245/505 which would be (505/245)= 2.06. Now I'd like to understand how this ratio is lower for the SO 99's than it is for every other generation of cummins. My reasoning is that the lower compression ratio lends itself to lower torque, but higher HP. Is this correct or am I way off here? I've read that the TST kit for the 12v's will make 230/605. That's (605/230)= 2.63. I want that kind of torque!

'99 dodge 4x4 NV4500, Super X VP, FASS 150, Custom Quick Spool Super B w/ ATS manifold, RV's, Smarty programming. north of 400 hp... Bout to add water/meth injection

Last edited by bbraden; 01-12-2009 at 11:48 AM.
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post #7 of 9 (permalink) Old 01-12-2009, 11:51 AM
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I see what your getting at, im not sure if its right but i see your point. Modified you shouldnt notice the difference in the HO an SO though. At least till you get to ~450hp then the HO pump will make it harder to get over 500hp.

Hopefully someone on here with more engine experience can help ya out.

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2000 QCSB, 180 pump, 6x.013's, maxspool 2.5, s364/s480, tranmission built by me, AD150

11.23 @ 121mph
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post #8 of 9 (permalink) Old 01-13-2009, 11:16 AM Thread Starter
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bump to the top

'99 dodge 4x4 NV4500, Super X VP, FASS 150, Custom Quick Spool Super B w/ ATS manifold, RV's, Smarty programming. north of 400 hp... Bout to add water/meth injection
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post #9 of 9 (permalink) Old 01-14-2009, 08:37 PM Thread Starter
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My super-x VP advances timing... I'm not sure how much, but you can hear the difference when it idles. Do you think that with the Edge comp on I just have too much timing?

'99 dodge 4x4 NV4500, Super X VP, FASS 150, Custom Quick Spool Super B w/ ATS manifold, RV's, Smarty programming. north of 400 hp... Bout to add water/meth injection
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