Engine thoughts....

[Formulaboy95]

Well, I have just about given up on my internally stock LT1. I have tried almost everything imagineable to get rid of the knock @ 4000 rpms. It ran 13.466 pulling 6* of timing due to the knock. I noticed everytime it knocks 6* or more, the check gauges light comes on bright, and goes away. Everything appers fine; oil pressure, voltage, etc...

So, I think it is time for a rebuild, or new engine. My goals are pro turbo kit 8-~16psi. Not sure if I want a 355 or 383.

Should I work this block, and get the proper internals.... or just buy an engine already setup for this? It is going to be a few months, but I am weighing my options right now. Any thoughts?

[MurphysLaw]

it depends on just how crazy you are

[Kevin - Blown 95 TA]

Well, I have just about given up on my internally stock LT1. I have tried almost everything imagineable to get rid of the knock @ 4000 rpms. It ran 13.466 pulling 6* of timing due to the knock. I noticed everytime it knocks 6* or more, the check gauges light comes on bright, and goes away. Everything appers fine; oil pressure, voltage, etc...

So, I think it is time for a rebuild, or new engine. My goals are pro turbo kit 8-~16psi. Not sure if I want a 355 or 383.

Should I work this block, and get the proper internals.... or just buy an engine already setup for this? It is going to be a few months, but I am weighing my options right now. Any thoughts?

Tried what? I think I remember you posting about it a while ago, but list the stuff you tried and maybe there's something else you missed. Knock can be a lot of things - too lean, too hot plug, egr malf, engine to hot, timing, and then the false knock whcih is the knock sensor picking up other noise like exhaust, or possibly rocker arm clatter, and a th3rd possibility would be mismatched knock sensor/pcm, burnt or damaged knock sensor wire, misinstalled sensor, or knock sensor system or O2 sensor malf.

[Injuneer]

Are you aware of what its going to cost to build an LT1 to handle 16# of turbo boost? I'd say you are looking at $15-20K for the engine and computer alone. Add another 50% for the drivetrain and suspension mods required to handle the power. That's a high price to pay because you are upset with knock retard.

How are you measuring knock retard.... data logger or scanner? Who did your tune - do you have a tune? Have you checked with the tuner on the source of the problem? Have you tried removing the "IAT spoof" (I assume that's the resistor)? That alone can get you into advance problems.

[fastTa]

I'm with Kev and Fred. it sounds liking you are just jumping to extreme conclusions. Genuinely and wholehearedly attempt to tackle the knock problem.

You are either getting real knock retard or false knock retard. That would be the first way to diagnose the problem and start to rule things out. With your LT4 KM, my bet would be strongly on false knock. Get in on a scanner. Test the actual sensor itself with a meter. Look at your valve lash...possible loose rocker arm. Look for an exhaust leak near the sensor. Look for a loose motor mount. Monitor your coolant temp. Look for cylinder misfires. Etc, etc., etc..

Some have found success in wrapping the threads of the knock sensor with teflon tape, but that is merely a band-aid in an effort to stop false knock.

If I decided to build a 25k motor everytime I got frustrated with an ignition/PCM problem I would have been in the poor house long ago.

[redbird94]

man just get the 383 kit and lt4 top end then you could run a sts turbo kit at 8 psi youd be running 600-800 hp thats insane, then all new coils race shocks, subframe panard bar, lcas dyno tuning and some slicks
i think you could live with that aye?

[Kevin - Blown 95 TA]

Only problem is that is even harder to tune a turbod 383 than the engine he has now, and unless he goes to an aftermarket engine management system or disables the knock sensing system, he might have the same problem. Or if he incidentally fixes the problem during the engine swap, then the new engine didn't realy solve the original problem.

[N20LT4Bird]

Why dont you post some data so we can help you figure out the knock problem. One of my students brought in his 98 T/A with the same problem, except the PCM was pulling 4 degrees. We figured out the problem after 20 minutes on the scanner and a fuel pressure test. The pump is going bad and pressure was dropping under hard excelleration. Easy.

WHat is your fuel pressure? Under load? Fuel trim on the scanner? Misfires? Etc.....I agree with the other guys here. 20k to fix a timing issue (maybe fix it) is a lot to dump. It could be as simple as a 10 dollar fuel filter.

P.S. 16 PSI on an LT1 is insane....this isnt a 4 cylinder honda with 8.5:1 compression!

[Formulaboy95]

Sorry for the lapse... New job has to come first.

Updated list of what I did since the last post...

Earls Pressure master header gaskets, w/stage8 locking bolts
Replaced both engine mounts
Re-Routed KS wire (used cool tube for extra shielding)
KS was replaced with matching GM part #
Removed LT4KM - Replaced w/LT1 KS
Removed IAT resistor
New NGK TR-6 @.037
New Taylor wires w/made4u looms
Cleaned Opti & Sealed w/silicone, Rebuilt on the car (seated perfectly)
Re-did all engine grounds
Cleaned EGR valve
Replaced Fuel Filter
New PS Pump, New Alt, New WP
... the list goes on ...

I tried TTS Datamaster also. Data seems to be inconsistant. Data errors pretty often. On 1 WOT run, it says I am going +80% DC on the injectors before 3300 rpm. Next run injectors are fine. Only thing I can count on is the knock at 4000 rpms. Knock still happens with 100 octane mix.

It could be carbon deposits causing a hot spot too.... Or a bearing, or piston slap, etc....

My last resort is to pick up a new pcm, replace egr, ICM, IAC, MAP. (PCM has stock program)

I noticed when I first took the car to the track in 2003, that the top end had no pull after the 8th. Kinda felt like it kicked down. I figured it was the stock heads/headers that just couldn't flow much more. So, then came the nitrous/headers - something to help the top end. So I believe the knock problem was there before modding.

Here is the thing that concerns me. I HAD a wet nitrous express kit in, using 50-75hp jets. All Safety equip is NX: FPSS, Window Switch 3000-5600, TPS switch, Bottle Heater. When I had it dynoed, relatively stock it put down 275 RWHP/296 TQ. With the 75 shot jets - 317RWHP/379TQ. The A/F spiked up to 14.2 and went down to 13.0's. As soon as I found out that this was "dangerously lean", I pulled the nitrous out. I have since upgraded the pump to a walbro255lph. The FPSS was pulsing on/off, and the dyno shows it.

Valvetrain is noisy, and so is the rotating assembly. If the other sensors don't fix the problem, then I am probably going to pull the heads. If I pull the heads, then I am going to send them out to get worked by lloyd elliott. At that point I might as well get the block setup for my future plans. I plan to add a front mount turbo. As far as how much boost I want to add - I would like to be safe for now, but have room to handle more psi later on. I know I can't afford an expensive fuel management system yet, plus 9", etc... but probably will in the future.

[Kevin - Blown 95 TA]

Some guys have had problems with the ignition module heat soaking and causing the ignition to misfire and have moved it away from the driver's side head to keep it cooler. It might be worth a look.

[Joe 1320]

Some guys have had problems with the ignition module heat soaking and causing the ignition to misfire and have moved it away from the driver's side head to keep it cooler. It might be worth a look.

That and I've seen mis-aligned pins in the module harness connection that gave the exact same symptom. I chased my tail for weeks until I found that.

[Formulaboy95]

LOL.... more variables in the equation. (kidding)

The thing that really gets me is the "Check Gauges" light blinking on, basically as soon as the "knock" event occurs. Seems like the more timing being pulled, the brighter the light. Sometimes I am seeing 10+degrees of timing being pulled @ 4200rpm. Basically seems/feels like the engine hiccups. Kinda like it goes from pulling crazy, and something pulls the power plug out for a fraction of a second, then it comes back on. It's hard to describe.

[N20LT4Bird]

If youre running lean on the dyno, why not focus your diagnostics on the fuel system?

Whats your fuel pressure at WOT? Does it drop off at all? Even though you have a new pump, it could still be bad. And I have also seen the clamps on the rubber hose in the tank come loose and make a major leak in the tank, bleeding off a lot of fuel pressure....