Building my LQ4 engine in my Denali XL

[Ridculous]

Well like the title says I am in the process of building a engine for my Denali XL due to oil starvation to the top portion of my motor, failure to 4 CAM bearings, damage to my CAM, damage to my lifters and valve springs and #8 cylinder....the engine only had 128k but I have been towing my 7000lbs travel trailer from Tulsa, OK to the Rocky Mountains 2x a year in the summer time. It stinks but when life gives you lemons make lemonade ...so I have my local GMC dealer break the entire engine apart and had them ship it out to the local race / engine builder in town. So they are currently checking the block, heads and other engine parts to see if they can be reused. This is the only dealer that I have ever encountered that is willing to put on and even recommend aftermarket parts and engines and install them!

The outcome I am looking for in the denali XL version 2.0 is
1) Durability to at least 100k before a rebuild
2) Torque down low to tow my trailer in the mountains and get this pig off the line (want a nice flat power band from 1500 - 5000)
3) Keep my piss poor fuel mileage at or close to 9-10 MPG in the city and 14-16 on the highway (7-8 towing)
4) Power goals at the crank figure 525+ hp and 500+ lbs


So far I've talked to a couple of builders and tuners and thinking either

Option 1 - N/A engine stroked to 408 - 416 CI with a nice small CAM and ported heads and new forged internals including crank

Option 2 - FI engine stroked to 408 CI with all forged internals, blower CAM with a Magnacharger 2300 sitting on top

I will be building the stock transmission as well to hold the extra power.

Also this is our family car and my wife and nanny drives this as well so can't be to crazy (loud)... I'll post more information later this week after I speak with the machine shop!

Budget for the build is between $10-$18k

Let me know your thoughts!

 

[Mister H12]

I vote Supercharged lemonade

 

[FreshLikeOprah]

You can make 525 crank HP without needing FI. Stock crank, rods (since yours is a 05) and go .030 over with some Diamond forged pistons. Flat tops. A set of 317 or 243 heads, with a nice port job. Full bolt ons, and a cam in the mid 220s duration. You'll have nice torque, make over 400hp at the tire and be reliable. Probably do a 07+ Intake with a LS3 Throttle Body. You'll need a Link X control box to run it. As for your trans, a 4L80e is really a better option. Esp being in a big heavy XL. A stock 80e with just a shift kit will be all you need. And maybe a tight 2500-2800 converter.

 

[YukonXL04]

If your going to be towing in the rocky mountain area at high elevations, then definitely go with FI.

 

[Ridculous]

Thanks guys for the input. Priced out a Magnacharger with the upgraded 2300 (Radix blower) shipped for $6400....

I'll update the post as I get more information!

---------- Post added at 01:27 PM ---------- Previous post was at 01:18 PM ----------

Also what type of headers should work on the 408 cubic inch

 

[FreshLikeOprah]

Definitely go with 1 7/8s. America Racing headers and Kooks are the best you can buy. Texas speed makes some nice long tubes also. But go for the 1 7/8th whatever you buy.

Was just trying to save you some coin. That's why I was saying you don't need to go all out if you only want mid 500s HP.

 

[Ridculous]

Thanks boss great suggestions on the headers. Question is will the N/A have that 500-550 lbs of torque between 1500-4500 that I need. Having 500+ hp is nice but need the torque to pull.

 

[YukonXL04]

Yeah it should being a stroker motor... However it won't pull near as good at high elevation as a forced induction motor. And I'm all for NA, but not when your at higher elevations, especially when towing something heavy...

 

[Front Street]

Excited to see what you decide on. I'm pricing my engine build on my 04' Denali right now. Don't have the budget for a supercharger, so I'm going more the route you are on the N/A option. Kooks headers are the #1 recommendation and like others said, 1 7/8 are what have been recommended to me almost 99% of the time. I'm going for similar HP #'s, but reliability and more efficient power are my goals. So far, it's a Lunati Cam, Trick Flow heads and great internals, the only thing to really decide on is the intake and TB. Drive by wire is what I think I should stay with, but haven't asked the engine builders about that yet.

What are you thinking for an intake and TB? Guys love FAST, but some have said the gains aren't worth the $1000.00.

 

[josueh95]

ever thought about a torque converter and a tru cool 40k tranny cooler? thatl get you in your torque curve alot easier

 

[livingez_123]

You can make your 500hp goal with the truck intake and a nice polished TB. if you tow 5-9k lbs, you will want a cam that comes on before 1500. a loose converter and towing heavy don't mix. converter slip (until it locks) creates unnecessary heat.

ATK builds a 408 short block for about $3,700

 

[Ridculous]

Thanks for the responses and information guys!

I already have a Trucool 40k transmission cooler and have been discussing the shifting point / stall with my tuner so we will see if a new convertor is apart of a build transmission.

I think I'll upgrade to the Kooks headers (had them and a vortech SC on my Jeep SRT8 and liked them). At this point those my goal is NOT horsepower it is 500 lbs of torque down low....if I get that same in HP great. HP doesn't allow me to tow 7000lbs of travel trailer + the weight of the Denali XL + 2 kids + 3 adults and 2 - 100lbs dogs very well.

I did speak with Texas Speed, ERL and ATK about a built short and long block...at this time (still waiting on the local engine builder to clean my block) I plan on using my block and have it built locally vs. waiting 4-8 weeks for another shop to build it and ship it too me.

I think I'll chance my license plate to the griswolds!

 

[FreshLikeOprah]

Go to Performancetrucks.net... There is plenty of knowledge over there. Those guys have a PH.D in LS engines.

 

[Ridculous]

Yes sir that is where I have been starting my search

 

[Front Street]

Keep us posted!

My LS guy also likes parts from Texas Speed, he used them in a TBSS build almost a year ago and the guy loves his engine. I'd love to hear what you go with to get the Torque you need.

I too am going local for the build, which is always cool to help out our neighbors. Plus, I've learned that doing a cool out of the box build will get you into the network of hookups and discounts for all kinds of stuff! It's pretty exciting to be able to make connections to powder coat guys, dealer hookups and other areas.

Hope you find the same is true!

 

[M Hankel]

If you go FI you don't really need to stroke it to a 408 to get your hp/tq goals. It's just added cost for not much gain.

For a FI build, I'd do a 370, which is a stock crank, forged rods and forged pistons (.030" over bore). The stock crankshafts are nearly unbreakable up to around 900+hp. Put the money you saved from not needing a stroker crank toward a good roots style blower, preferably one with a built-in aftercooler. A roots or screw type blower will give you exactly what you want, which is a lot of torque down low and instant throttle response. With this style blower you won't even notice not having a stroker engine. If you go this route, make SURE your engine builder knows this will be a forced induction engine so he can gap your piston rings accordingly.

Pulling a heavy load on a long mountain pass with a steep grade will build a shit ton of heat so you'll need a way to keep (IAT's) intake air temps in check so you might look into a meth injection system.

Keep the stock 317 heads and drop in some good valve springs with at least 150lbs on the seat pressure. Those heads will work perfect for you hp goals with the forced induction.

Budget for some decent fuel system upgrades, pump/s, injectors etc.. That stuff can add up quick.

Run as big of a header as you can afford, size the exhaust accordingly. The 1-7/8" would be perfect IMO. A 3" y-pipe to a single 4" or dual 3" exhaust.

Research a good trans builder and talk to them about your goals. RPM transmissions is one of the best when it comes to these autos.

Good luck man.

Mike

 

[Ridculous]

Found out that if I go the supercharger route I can only run 91 or better.....going N/A so I can have the option of different fuels on this bus.


Callies Dragonslayer rotating assembly, arp head bolts, studs, blue printed block, ported stock heads, new lifters, valves, retainers, push rods and other goodies ordered plus a new comp cam

Will be ordering next week a set of high flow catted headers, injectors and possibly a new intake manifold (or stay stock intake or TBSS to retain more torque?)....then work on the transimisson

Stay tuned!!

 

[livingez_123]

If you go FI you don't really need to stroke it to a 408 to get your hp/tq goals. It's just added cost for not much gain.

Really? your nuts Hankel. The 408 in NA form will give him more torque than the 370. And if in the future he wants to do a mild turbo or blower build he will have 500+ftlb of torque when ever he needs it. the longer stroke of the 408 is what gives him the torque he wants, the 370 will be a disappointment because he will have to run a larger cam to get the ###'s he wants. the 408 will provide the ###'s he wants with a smaller cam. and if he goes turbo/blower he will allready have a good cam for it.

Remember the saying...theres no replacement for displacement. The 408 is a perfect motor for someone who intends to tow.

 

[M Hankel]

If you go FI you don't really need to stroke it to a 408 to get your hp/tq goals. It's just added cost for not much gain.

Really? your nuts Hankel. The 408 in NA form will give him more torque than the 370. And if in the future he wants to do a mild turbo or blower build he will have 500+ftlb of torque when ever he needs it. the longer stroke of the 408 is what gives him the torque he wants, the 370 will be a disappointment because he will have to run a larger cam to get the ###'s he wants. the 408 will provide the ###'s he wants with a smaller cam. and if he goes turbo/blower he will allready have a good cam for it.

Remember the saying...theres no replacement for displacement. The 408 is a perfect motor for someone who intends to tow.

You do realize I was saying if he decides to go with a blower like a magnacharger that going with a stroked crank is not needed. A blown 370 will make 450-500rwtq by 2500 RPM. Show me a naturally aspirated 408 that can even come within 60-80 of that number that low in the RPM range (towing range).

There is a replacement for displacement, it is forced induction or nitrous.

Mike

 

[Ridculous]

Been looking for a nice set of catted headers to keep the drone and noise down for the family any input on people with catted LT headers....looks like not too many options

OBX for $800-$900
AMERICAN RACING $1500-$1600
and maybe Kook's long tube headers are the only ones I have found. All LT headers are going back on the stock exhaust. Going cattless is not a option due to the noise. My wife had me remove some aftermarket exhaust on my old SRT8 jeep because of it. Your thoughts and recommendations are welcomed