[Flbandit98]

Here is the Link to my 95 TA video, please let me know what you think!!!

http://www.youtube.c...be_gdata_player

[Injuneer]

Sounds really healthy and mean.... I like. Really clean as well.

What are the cam specs? Sounds wilder than the custom solid roller in my 381 (230/242 114LSA 0.590/0.590). I'm guessing you have a narrower LSA.

[Flbandit98]

Injuneer, on 06 February 2012 - 09:48 AM, said:

Sounds really healthy and mean.... I like. Really clean as well.

What are the cam specs? Sounds wilder than the custom solid roller in my 381 (230/242 114LSA 0.590/0.590). I'm guessing you have a narrower LSA.

Thanks Fred!
Since I have 1.6 ratio roller rockers does that change the total valve lift? I have been told the stock ratio was 1.5?


The cam specs are:


CCA-07-500-8UPC036584063193 Cam StyleHydraulic roller tappetBasic Operating RPM Range1,000-5,000Intake Duration at 050 inch Lift206Exhaust Duration at 050 inch Lift212Duration at 050 inch Lift206 int./212 exh.Advertised Intake Duration258Advertised Exhaust Duration264Advertised Duration258 int./264 exh.Intake Valve Lift with Factory Rocker Arm Ratio0.480 in.Exhaust Valve Lift with Factory Rocker Arm Ratio0.488 in.Valve Lift with Factory Rocker Arm Ratio0.480 int./0.488 exh.Lobe Separation (degrees)112Computer-Controlled CompatibleNoGrind NumberLT1 XR258HR-12

[Injuneer]

The Comp Cams data sheet for that cam indicates the lift with stock 1.5X rockers is 0.480" intake/0.488" exhaust. With 1.6X rockers, that would be 0.512 intake/0.520 exhaust. LSA is 112-deg. Surprising that it sounds that awesome. I would have guessed it was way bigger. It's a very small cam for a 383, not a whole lot larger than the stock LT4 cam, and smaller than the LT4 HOT cam. I have a video of my setup, but its on a chassis dyno, and the fan for the dyno is overpowering the sound of the engine.

Did you set it up with a lower compression ratio (64cc combustion chambers) so you can add a blower in the future? Or did you compensate for the larger combustion chambers with domed pistons?

[TheBat]

that thing sounds meeeaaaannnn....get another vid n have someone rev it for you...i could only imagine how she roars

[Flbandit98]

Injuneer, on 06 February 2012 - 11:02 AM, said:

The Comp Cams data sheet for that cam indicates the lift with stock 1.5X rockers is 0.480" intake/0.488" exhaust. With 1.6X rockers, that would be 0.512 intake/0.520 exhaust. LSA is 112-deg. Surprising that it sounds that awesome. I would have guessed it was way bigger. It's a very small cam for a 383, not a whole lot larger than the stock LT4 cam, and smaller than the LT4 HOT cam. I have a video of my setup, but its on a chassis dyno, and the fan for the dyno is overpowering the sound of the engine.

Did you set it up with a lower compression ratio (64cc combustion chambers) so you can add a blower in the future? Or did you compensate for the larger combustion chambers with domed pistons?

Hi Fred,

I could be wrong on the cam. The previous owner built the engine and really didn't give me allot of details or records on what he put into the engine. I have had to research most of it by myself. Since I had the oil pan down to fix leaks I know it has the stroker kit. Also had one valve cover off to confirm the rockers. It could well be the next higher Xtreme Energy cam which has .488 lift on the intake side. I know he told me the car is programmed to shift at 5,800 RPM so I am not sure why you would program it to shift that high if I had the other cam I told you about earlier that has a 5,000 RPM limit?

[96TA]

Sounds great, looks awesome..

The lights should not come up with the running lights on, you may need to look at the system, mabe gears are going bad or grinding when they go down.

[Injuneer]

I assume your mods list on the video website is based on what you were told. It would be worth tracking down the details and verifying the parts, because some of them are sort of unusual choices. Do you have any sort of dyno sheets, or 1/4-mile time/MPH?

LT4 ported intake - exactly what did they port? Obviously, if they bolted the 58mm throttle body on, they should have opened up the throttle bores to match (stock bore is 54mm). With regard to the intake runners, they are no different than the stock LT1 intake runners. There is just more metal on the top of the runner to allow them to be opened up to match the GM LT4 heads' raised runners. Problem is, GM ran out of money on the LT4 development project, and never really finished the LT4 intake. It makes sense to port them only if the heads have the raised runner ports. But it take a lot of expertise to get the max performance out of them.

58mm throttle body - OK

Comp Cams Extreme Energy 480 lift roller cam - as noted, too small for a 383

1.6 Scorpion Roller rockers - OK

Patriot 64cc heads - Odd choice. As noted the 64cc combustion chambers are way larger than the stock LT1 heads (54cc). People building blower motors often use 64cc heads to lower the compression ratio so they don't have to go with large dish pistons. Additionally, the head flow shown on the Patriot website indicates they flow fair at 0.600 valve lift, but the cam doesn't come anywhere near that lift, even with the 1.6X RR's. Then there's the issue of why use the Patriot when a quality port on the stock LT1 heads would yield about 10% better flow than the Patriots.

Kooks stainless long tube headers - What primary size? These are the Cadillac of LT1 long tubes.

3" Y pipe - Do you run cats? What size it the intermediate pipe (from the Y-pipe back to the muffler)?

Flowmaster Muffler - which one? The lower the "series" number the better they flow, and the louder they get. I had a 30-series race muffler, but it was part of a Mufflex 4" catback with a 4" intermediate pipe, and a single 4" outlet on the muffler. Sounded throaty, but had an almost annoying resonance at about 2,800rpm.

2k stall converter - Anything under 3,000rpm is of limited benefit, but with a cam quoted to operate best in the 1,000 - 5,000rpm range, I guess there's no point in going higher than they did.

built trans will all HD parts, Corvette servos. - Any idea who built it? All LT1 and LS1 4L60E's have Corvette servos from the factory. Everyone assumes because it's a Corvette part, it must be an upgrade, but direct from a shop that specializes in building the 4L60E for 4th Gens, they all have the Corvette servos if they came out of a V8 car.

Any idea who tuned it?

Looks great, sounds great, and you have the foundation for a really potent engine. Just need to optimize what you have.

[Flbandit98]

Fred, thanks for your input. I too am questioning the choices that were made during the engine build and what the guys objective was? I still do not know!
I called Second Street Speed shop yestereday and talked to Bill Hunsberger and he looked up the files for the tune on my car. Well he has tuned it for Open Loop operation. So that is why it constantly runs rich. I hooked up my laptop to the car yesterday and verified this. One thing I saw while watching the parameters was that the #2 O2 sensor is reading way higher than the #1 O2 sensor. It was up around 799 mv while the #1 O2 sensor hovered around 180 mv. Seems strange to me!
I am going to look into tuning the car for closed loop operation. I think this would be much more efficient and hopefully fix my horrendous gas mileage!
Have you heard of this guy before? http://www.lt1pcmtuning.com/
I am considering having him help me with a closed loop tune.
I guess the only way I could see if I have domed pistons would be to pull a plug and look inside with a boroscope lol.

[Injuneer]

If it's at idle or under part throttle, you want the O2 sensors to be as close to 450mV as possible. At WOT, you would be looking for something in the 850-900mV range. The two O2 sensors should be close at WOT, but it takes very little difference in actual A/F ratio to make a large difference on O2 millivolts when operating at the idle/part load condition. The stock, narrow-band sensors are meant to operate while cycling over a range of +/- 0.05 A/F ratio units. That's the range the PCM has to swing the A/F ratio back and forth in closed loop to allow the cats to work.

A small exhaust leak before the O2 sensor can cause a lean reading, as could a slightly dirty injector limiting fuel flow. In one case, its not really running lean, and running open loop prevents the PCM from adding fuel the engine doesn't need. In the other case, one cylinder could be running lean, and in closed loop the PCM would be adding fuel to all four cylinders in that bank, maybe helping, and maybe hurting the tune. That's the nature of open loop tuning - doesn't respond to a "false" lean, but then it also doesn't respond to an actual lean condition.

[Flbandit98]

I just found out I am completely wrong about my cam. It's a CC306 which has the following specs:
Cam Style
Hydraulic roller tappetBasic Operating RPM Range
1,800-5,800Intake Duration at 050 inch Lift
230Exhaust Duration at 050 inch Lift
244Duration at 050 inch Lift
230 int./244 exh.Advertised Intake Duration
290Advertised Exhaust Duration
307Advertised Duration
290 int./307 exh.Intake Valve Lift with Factory Rocker Arm Ratio
0.510 in.Exhaust Valve Lift with Factory Rocker Arm Ratio
0.540 in.Valve Lift with Factory Rocker Arm Ratio
0.510 int./0.540 exh.Lobe Separation (degrees)
112Computer-Controlled Compatible
NoGrind Number
LT1 290HR-12

[Injuneer]

That makes more sense. Should keep pulling above 6,000rpm. Now check the stall. I'd bet maybe 3400 with that cam.

[Flbandit98]

So with this cam and 1.6 rockers I am looking at total lift of .544 intake and .580 exhaust. So that is why it sounded bigger like you thought.