What’s the improvement of the Holley computer over the stock unit? I imagine ease of tunability or maybe increase in processing power/capability over the stock unit. Does it really make that much of a difference?

Also, you mentioned your tune is much better than your last tune, are you tuning it yourself or just found a better tuner to do it?

I like the way your build sounds, I think for what I’m doing, if using your setup, I’d go with a cam slightly milder than what you’ve got now, maybe a 220/226, lessen valve overlap between intake and exhaust valves a little more. To be completely honest, I had to play it back a couple times to get a good listen as my attention kept getting drawn to the blue C4 in your garage as you’d pan the camera around. Gosh I miss that car.

I know you mention the heads are already ported due to it coming off an H2 motor that used a blower, do you think the stock 317s would make any difference to what you have now since they appear to flow pretty well already? Probably just keep the power curve on the lower end, yea?

The 4L65E - how has that done with the lift and 33’s you have now? Any issues with it so far, and is it stock or did you have it built for the application? How difficult was it to make it work with the LQ4?

Since you mentioned you’re using electric fans, how are your temps in the city in traffic? I was planning on keeping the mechanical pump since the airflow is supposed to be way better while moving than the electric fans (8000-10000cfm compared to the 4000cfm of most good electric fans). What radiator are you using for cooling?

 

It's an Elgin cam. I ran a tsp 228/232 .600 lift at first and it pushed the powerband higher than I like so I dropped to that cam. Stock truck intake with 78mm ported throttle body.

 

As a C4 owner, I can confirm that they are very slow lol. The LT4 and LT5 powered ones were the only quick ones.

 

I have been doing the tuning, with both systems. It's my first timing doing so. Here are the items that I like with the Holley:

1) The tuning software/interface is more intuitive/clean with the holley, in my opinion
2) I have less items in the SW 'fighting' or modifying the end results. I had lots of issues where I spent time trying to figure out what in the SW was pulling timing. Better tuners wouldn't have issues here probably, but understanding all of the connections between high octane table, low octane table, knock retard, burst knock, etc. I didn't like it.
3) Closed Loop, even in wide open throttle, the Holley is always watching/correcting.
4) Fuel - learn. I *could* do this functionally the same with my HP TUners and my wideband, but there, I'd drive with a laptop, log data, get the histograms, adjust the tables, reflash. With the Holley, most of those steps are automatic, and I just click a box to transfer the learning trims to the base map. Which brings to:
5) I don't need a laptop in the car. I can do all of my datalogging / recording onto an SD Card, and then play back my drive at home on my laptop. It's a convertible, with no locking top, so it's a benefit to not need my laptop with me, for rain and theft reasons. I can always grab a datalog when I need it, without planning ahead.
6) When I *do* play bag the log files, you can watch the SW and it shows you which cells it was running in your maps. So if I see a lean spike, it shows me the fuel, spark, VE tables right then, and I can watch it move around in the playback. This is a real benefit for someone like me learning
7) When I Want to, I also *can* bring my laptop, and now watch the tune running live on the screen. And I can do live tuning, and adjust values on the fly if needed.
8) I have multiple tunes on my SD card, which is on the 3.5" handheld in the car. So I have multiple tunes, and they are very fast to load/switch between. So I can make changes, but still have my one file called "Known good tune", and if I don't like my latest file, I can just swap back, again, without any laptop.

I have the 3.5" handheld mounted under my dash so it isn't really visible unless you are in the car. And not so theft-worthy as a laptop.

If I had a car with other CAN communication to the cluster and body controls, I'd consider a factory ECU, but in my case, there was no reason not to switch

Hehe, it's a fun car, I love C4s. That one is a 1992, in the bright aqua metallic. I have waffled over what to do with the earlier mentioned LS2, which is now a 403" stroker. Put it in the C4, or into my 1967 Plymouth Valiant... right now, the Valiant is ahead in the running.

I am guessing I'd lose about 20HP with stock 317 heads. In those Iron Maiden articles, it appeared that 5.3 heads were the best. MY cam had a ton of lift, so I can take advantage of the heads I have.

My LQ4 and 4L65e are a matched pair, both are from the Hummer H2. So it's a direct bolt up. In My application, I have a passenger drop front axle, so I used a mid 80s NP208c transfer case from a later Blazer. To mate them, I use an Advance Adapters 6 bolt to 4 bolt adapter, which also supplies my VSS signal, and the GM factory 700R4 to NP208 adapter. The transmission is more or less stock, but I did drain, clean, and install a new filter. I also swapped the stock 2nd gear servo to a Corvette servo, which has more holding force (servo area is larger) than the stock 2nd gear, to my understanding. As mentioned, I have the Yank converter, which is also recommended for the gears and cam I'm running. I have a plate style trans cooler in front of the radiator. I didn't see any rebuilt tags on my trans (my engine had a GM remanufactured tag, but appears stock bore from my measurements). There are not much clutch material in the pad or behind the servo in my 4L65e, so seemed in good shape. HOnestly, I beat on the truck every time I drive, it handles it well. 1st-2nd shifts are set for 6700 rpm, and it shifts crisp and hard at that point.

https://www.advanceadapters.com/prod...onadapter-kit/

I have no issues. I am running a modern replacement for the 4-code HD radiator for trucks of the same vintage as mine. I.E. $100 Autozone piece with plastic end tanks. 3 years, no issues. I have the stock thermostat which starts opening around 187 degrees. On the highway, I Will run steady at 190, so this tells me the cooling capacity is good, as thats basically thermostat temp. My fans are 90s Ford Windstar fans, (A $90 Dorman replacement one from Amazon), wired high (fans wired in parallel), and low (fans wired in series), so both fans operate in each setting. My Holley turns on low fans at 205 degrees and turns them off at 195. In stop and go traffic, it'll cycle between those ranges. I forget the high fan settings. In 3 years, it has never, not once ever got above 209 degrees. The high fan setting has never turned on, which I think I have set for 215... and it will always cool down quickly to 195 and turn off the fans, it never sits with them running full time. Likewise, the trans temp sits at 168 degrees most of the time, and will get to around 178ish if I start stoplight racing. This year we did 280 miles of cruising and stoplight launches for Woodward cruise and it never gets out of these ranges. So I am very happy with it.

 

All depends on what was done, right

My blue one is slow (LT1 + 4L60). My Jimmy is faster than it for sure, at reasonable speeds. Those 2.59 gears at to blame. I think all LT4 cars were 6 speeds with 3.45 gears. If I toss my Dana 44 rear with 3.33s in, it's wake it up. Bought it to LS swap the car, just never did it. Funny, how there isn't much LS swap activity with those things. I like the styling, size, and visibility better than later generations. Of course, I graduated high school in 1992, which is why I got my 92 BAM...

 

I think slow is relative to your experience. The 94 I had wasn’t a slug by any means, it’d take off from stoplights and hold it’s own on the highway pretty well. As a base 4 spd LT1 with 2.59( I think?) gearing, I was pretty darn impressed. I really enjoyed both cruising with it and taking it around the city. Granted, it wasn’t nearly as fast as the 500hp+ C6 I got to drive a few years prior, but it soared past 100 pretty well. I sold it in September of last year and have missed it ever since, though being able to drive through the city and sit in traffic with the AC on instead of the heater is really nice. I don’t think I’ve ever not watched my temperature gauge on anything since. I’ll have to see if I can throw up a couple pictures of it on my profile.

 

With a truck application I think the 862/706 heads will be fine, the 243's would probably only be better above 5000 or so rpm anyways

As far as getting a motor goes I would ONLY get the drivetrain from a wrecked truck, and preferably less than 200k that way you know it was in running condition before you got it.
If its local pull a valve cover and check for sludge.

Sounds like your not wanting to do F/I but with low boost say 7-8psi with good tune, and air to water inter cooler the reliability would be better than having to rev the engine higher to get the same power.

 

Is the lt5 the early 32 valve zr1 from 1990 era, and the lt4 would be '96 gran sport model

 

Yessir, the LT4 was released in the 96 year for the grand sport, and the LT5 was produced from 1990-1995, with a performance increase in the 93-95 years.