Hi everyone,
I need some bin advice.
I'm finally gonna do some changes to the car, (it only has 30k on it).
Here it is I ordered the LT4 Hotcam for my 91 L98.
I ordered 1.6 rockers as well.
I have a FirstFuelInjection intake system to put on it.
AFR heads are in the near future, as well as a free flowing exhaust with headers.

Are there any warnings, tips, opinions, ect that you guys have for me? What specifically in the bin should I be looking out for?

I remember someone telling me that only a fool learns from experience, a smart man learns from the experiences of others. I'm trying to be smart. So anything you have will be well thought upon.
Thanks in advance.

 

Well not bin related but, if you put that cam and those rockers on stock heads with stock springs I would be more worried about that. Stock springs can only handle about .450 total lift.....

 

What I meant was is there anything that's often overlooked when I do my programming - any tips or tools to make it easier to log, construct tables, what not to forget, ect. Like I said any advise (especially any info programming related), would be greatly appreciated.

Have any of you installed the Lt4 hot cam .....how did have to change your values?

With a TPI intake that flows 300cfm per runner what do you expect to happen to AFRs?

Theorycrafting welcome .....give me some stuff to think about .

 

anyone?
I value all opinions.

 

In general, it's a bigger cam, so you'll need less fueling down low and more fueling up top. How little down low and how much up top will come from your datalogging and plug reading. FIRST Injection is pretty much a TPI on steroids so the fuel curve should generally be the same. Depending on the overlap of that cam, the O2 sensor will probably be useless at idle. You'll need to tune with plug readings, but I don't think that cam should be too bad to dial in. I run a TPIS ZZ409 cam which is much bigger and has 63* of overlap in closed loop just fine. I found that idle needed WAAAAAYYYYY less fuel down low... but I'm also running 36lb injectors.

I also second the above statement. You are asking for trouble putting 1.6 rockers and an LT4 HOT cam in with stock heads. The stock springs are no good and at .525 lift with the HOT cam and 1.6 rockers, Your retainers will most likely kiss the valve guide boss... not a good thing.

Oh and watch out for that half-*** TPS bracket that comes on that FIRST system. A friend of mine almost got into an accident because his TPS lever binded on it and got stuck at full throttle. Thankfully he had enough sense to throw her into neutral and stop and shut down. To fix it, I had to bend that bracket so it wouldn't make contact with the TPS lever. Oh it's also got a runner bolt that goes into a water jacket in the base manifold, make sure to use thread sealer on that bolt.

Yeah, I'm not a fan of that intake as you can tell... lol It is big and can flow a lot of air though.

 

I have Lt4 springs pn#12551483.

Im more concerned with the bin. I was thinking about taking tables from an Lt4 and writing them to a chip as a starting bin.
I have also read somewhere that L98 esc's are prone to pick up valve noise from aftermarket roller rockers, and give false counts. I already have cc ultra pro magnum 1.6's steel rr's. Can I do anything to the bin to take care of of the valve noise? Is there a way to "detune" the ks so its not so sensitive. The car is a 91.

 

A few idea's;
1. 90 degree pipe elbow
2. less torque on the sensor
3. thread tape on the sensor
4. relocate the sensor
5. Resistor
I'm sure others will chime in with other soultions, and why not to do some of the above as well.

As for #5 the resistor, I'm not sure how the Ks filter/processor works, but its basically audio stuff. If you know what frequency you want to try to filter out you can also make a bandpass, Low-pass, or High-pass filter. In the case of the resistor approach I think it would effectively "turn down the volume", which may also be achieved with an audio taper potentiometer. Of course that assumes the Knock filter is looking for a certain volume level (voltage) to reach some threshold.
If I had a scope I would have already figured this one out.

 

Punisher: Not sure if this appies but Polaris MFG once had issues with KS's. Fix was to add a thin nylon washer under the sensor and do not over tighten. Not sure if an automotive app allows this.

 

Great stuff so far guys. I thank all who have posted.

Since I'm putting in an Lt hotcam, should Itake the fuel/spark tables from an Lt and use those?

Anyone out there willing to do some theorycrafting? The intake flows 300cfm through each 17in runner. Ihave bins with just about every intake possible, but cant find 1 with a FirstFuelInjection intake. Which aftermarket intake plus hotcam do you think the tables will look like. Im trying to find a good starting tune to play with.

 

Id start with something with the same or similar cam. In my experience the cam tends to have a much bigger influence on the personality of the engine than the intake.

 

Is this on a 3rd Gen or a Vette?

 

Its on my vette.