Long time lurker, first time poster

**lonestarstash** · 10-05-2016

Hey everyone. I've been lurking around this forum, and many others, for years. Seems I can find the answer or information I need easily by using various search bars. So, I never felt that it was necessary to register. I'm heavy equipment diesel mechanic by trade. In my off time, my friend and I work with each other on our trucks. I enjoy reading and learning about efi tuning, but have little actual experience. Hopefully that will change.

Meet the Hellbound Cannonball
My truck is 1998 k1500. It's sat for over 2 years (I consistently work 70+hrs/week, hard to get anything done) when the transmission shop was dicking me around, but I finally got it back together, and made a few minor adjustments with JET DST. It ran like scalded dog for a couple months, then developed a rod knock. Long story short, I'm currently putting together another engine for her. She's a daily driver, 4x4, sittin on 34"s, and occasionally tows (I'll probably be towing a moving trailer across the country early next year) so nothing too wild. Mostly stock except:

880 block, .020" over, 4 bolt mains
Flat tops, 4 valve reliefs
Ramjet/383 cam, 1.6 roller tips, LS7 springs
Long tube headers, 1 5/8 primary, 2.5 collector, true dual, no cats
Updated spider assembly
Custom tune by me (that's why I'm here)

i know all about the HT383E, and how much more torque it's has for towing. Maybe in the future. I'm not one of these guys trying to find out how to make a 450hp engine "on a budget". But since I already had this block and rotating assembly ready to go, I decided to mock the Ramjet 350. I'll eventually get the marine intake and injectors. And maybe a 0411. But for now, the stock intake and pcm will do. The stock tune should be fairly tolerant of my valve train setup until after the break in period. Then, I would like to calibrate it for optimum performance, and the most torque that is safely possible in the low-mid rpm ranges.

Hopefully, with y'all's help, I'll learn enough about tuning to make that possible.

Nick

**Fast355** · 10-05-2016

Originally Posted by lonestarstash

Hey everyone. I've been lurking around this forum, and many others, for years. Seems I can find the answer or information I need easily by using various search bars. So, I never felt that it was necessary to register. I'm heavy equipment diesel mechanic by trade. In my off time, my friend and I work with each other on our trucks. I enjoy reading and learning about efi tuning, but have little actual experience. Hopefully that will change.

Meet the Hellbound Cannonball
My truck is 1998 k1500. It's sat for over 2 years (I consistently work 70+hrs/week, hard to get anything done) when the transmission shop was dicking me around, but I finally got it back together, and made a few minor adjustments with JET DST. It ran like scalded dog for a couple months, then developed a rod knock. Long story short, I'm currently putting together another engine for her. She's a daily driver, 4x4, sittin on 34"s, and occasionally tows (I'll probably be towing a moving trailer across the country early next year) so nothing too wild. Mostly stock except:

880 block, .020" over, 4 bolt mains
Flat tops, 4 valve reliefs
Ramjet/383 cam, 1.6 roller tips, LS7 springs
Long tube headers, 1 5/8 primary, 2.5 collector, true dual, no cats
Updated spider assembly
Custom tune by me (that's why I'm here)

i know all about the HT383E, and how much more torque it's has for towing. Maybe in the future. I'm not one of these guys trying to find out how to make a 450hp engine "on a budget". But since I already had this block and rotating assembly ready to go, I decided to mock the Ramjet 350. I'll eventually get the marine intake and injectors. And maybe a 0411. But for now, the stock intake and pcm will do. The stock tune should be fairly tolerant of my valve train setup until after the break in period. Then, I would like to calibrate it for optimum performance, and the most torque that is safely possible in the low-mid rpm ranges.

Hopefully, with y'all's help, I'll learn enough about tuning to make that possible.

Nick

I can tell you right now with that compression ratio I would use a different cam. Even with the factory 12cc dished pistons I have a hard time getting a decent advance curve in my setup. I would look for a 1995 LT1 F/Y-car cam or buy a replacement cam for a F/Y-car. The Marine cam is a bit of a dog compared to the F-car LT1 cam. I have full roller 1.7 rockers on mine and 2.02/1.60 valves and I still feel the cam falls off extremely early and generates excessive cylinder pressure that causes detonation under load.

**lonestarstash** · 10-05-2016

Thank you for the input. I'll start looking into that some more.

My thought process was that my calculated static CR is 10:1, about 0.5 higher than stock. There's some variations in the ramjet's specs depending on where you look, and I haven't seen a full cam card from GM. But, I believe the general consensus is that it has a bit more overlap than the L31 cam. I took all that into consideration and figured I could get away with it on 93 octane, and maybe an LT4 knock module. But, I very well could be wrong.

What type of heads are you using?

**Fast355** · 10-05-2016

Originally Posted by lonestarstash

Thank you for the input. I'll start looking into that some more.

My thought process was that my calculated static CR is 10:1, about 0.5 higher than stock. There's some variations in the ramjet's specs depending on where you look, and I haven't seen a full cam card from GM. But, I believe the general consensus is that it has a bit more overlap than the L31 cam. I took all that into consideration and figured I could get away with it on 93 octane, and maybe an LT4 knock module. But, I very well could be wrong.

What type of heads are you using?

906 Vortecs milled .020" and a .016" compressed head gasket for a .041" quench distance. Heads are ported with 2.02/1.60 valves. Running the marine intake, drive by wire 2001 8.1 TB, and coil per cylinder ignition conversion. I am right at 9.8:1 and its not happy at all with my travel trailer during the summer months.

Static compression is about 10.4:1 with a stock .028" compressed head gasket, 6cc valve reliefs, and .025" down the hole with a 64cc chamber. The Marine cam actually has the same overlap and earlier intake closing than the stock Vortec cam. The .006 timing is less than an OEM Vortec cam and the lobes are more aggressive. Your dynamic compression will be well over 8:1. I can dig the full cam specs out of the Mellings factory grind Marine replacement cam if you need them.

I am considering a LQ9 6.0 with a 2003 LS6 cam and TBSS intake as a replacement.

The LT1 cams wider LSA, later intake closing and longer duration will bleed off just enough cylinder pressure to let you run 10.5:1 compression on 93 octane. The LT1 cam also has a stupid flat torque curve.