Greetings,
A buddy and I put the Whipple and LT headers on earlier this year. Nice, but overall underwhelming so I decided to take the next step (and eliminate that annoying ticking AFM lifter) with cam, head work and AFM elimination.
I didn't want to tackle this myself and got a recommendation for Jason Wilhite in Creedmore, TX. We agreed on a scope using a Pat Guerra spec'd TSP cam (218/236 .610 119+4), TSP heads, LT4 HPFP and injectors, Comp Cams trunnion kit, DOD delete. After getting into the job a little Jason decided that a better option for the heads was Modern Airflow Dynamics in Houston.
The good:


The truck is now a hoot to drive. I replaced the fairly loud Carvens TR (2x in series) with a huge Walker MF muffler and it sounds great with the single 3" exhaust with cats. 9 1/2 psi max boost. This is with Pat Guerra tuning on a Mustang dyno. Pat says he gets around 275 rwhp on stock L83's so this is double the hp with only 66% more inlet air pressure. Good breathing and driveability. Heads flow well with LT1 exhaust valves, see attachments. In 4wd TC off it squirms some then grabs. It's a manual transfer case so it will be hard to be stealthy switching into 4wd at a stop light.
Highest injector pulse is around 4ms. Pat was using metric pressure, the magnitude was around 400, don't recall the units but I think LPFP was 40ish psi. It's got an alcohol sensor and there should be a little room to try an E85 mix. Motor sounds great, tight, no leaks. Likes to breath and run. A little extra noise due to new springs, possibly larger fuel lobe? Lots of other stuff that's no coming to mind.
The bad:
The LT4 HPFP interfered significantly with the Whipple intake. This caught Jacob a little by surprise and required rework. Welding and grinding wouldn't do it and a box finally had to be welded in. Would have been much easier if the issue had been known to him. But really, come on, Whipple. This in not a one time event. Fix the intake.
Modern Airflow discovered a couple of cracked exhaust valves at the 2 piece interface. Nobody makes 1 piece L83 valves without going full custom so they went with LT1. Only supplier is Ferrea for catalogue 1 piece and it took a while to get them. Then extra machining to accommodate to larger valves. Good for me,...…
The first new, GM LT4 HPFP was bad and it took a while to diagnose.
After it was finally together a miss developed, low compression on #5. Bent valve, turned out the lobe was too large causing contact and valve damage. Apparently a lot of rode work is going on by TSP causing power outages and glitches in machining. No 100% inspection? Shouldn't have to in this day and age but in my case it would have saved a lot of rework. They made good on parts and consumables, not labor.
4wd's are more work dropping the pan. Repeatedly.

Overall, super happy with the truck, Jacob, Modern Airflow Dynamics and Pat Guerra. Good, knowledgeable bunch of folks.

David

Noticed I called Jacob Jason. Typical.
Also wanted to comment that the quality control issue at TSP is by no means typical.

The exhaust valves are Manley not Ferrea.

Mistated, should have read LT4 injectors, LS7 lifters.
Whipple needs to do something about the manifold, for sure. It’s not a show stopper, IMO. If you’re aware of the issue and look for interference before trying to put it together it wouldn’t create a problem.
TSP is a good outfit. I didn’t talk to them directly but I assume they don’t do 100% inspection. You shouldn’t need to with all the modern tooling but the power interruptions caught them off guard. You can think of a few things you’d do differently if you could do it over. I have no problem buying from them but will discuss the need for inspection.

Thanks, yes I’m proud of the way it breaths. You’re challenging my technical capabilities but I’ll see what I can do with the sound clip. It’s a little lumpy when cold but steadies out pretty well.

Not yet but I plan on going. Not a high priority right now.