L83 5.3 with 7500rpm build - Suggestions?

[fozzi58]

L83 5.3, Whipple 2.9, LTRs, full exhaust. 118k miles, stock bottom end. Owned since new - well maintained.

Looking to refresh my motor over the winter. I would like to have a 7500rpm redline with a broad power curve. Looking for midrange power for track and AutoX. I'd like to see 550+ to the tire if possible, but high HP numbers not required; can be a byproduct. Having the motor pull hard from 2500-7000 is better. Additionally, with the 4.10's in the rear I am sitting at 2500RPM at 75mph which is a little high for my usual highway driving. Having endurance at 2500-3000rpm is more beneficial for the daily driving portion of the motor build, since I usually set the cruise to 80~85mph

I am trying to stay within a $13,500 budget for the motor parts and labor. I have some additional work that needs to be completed which is separate and falls outside the $13.5 budget. If there are issues with the motor that need to be addressed, I understand that will be additional (e.g. scoring on the crank bearings) This is what I have come up with thus far. Experienced engine builders feel free to make suggestions.

Bottom end:
Pull pan and rotating assembly
Inspect components
Gap rings to 0.024" to 0.026" to accommodate 12 lbs of boost safely
Reinstall factory assemblies
Install a high-pressure/high-volume Melling Oil Pump.
Install an SFI-approved ATI Super Damper configured for the Whipple 2.9L belt drive to stabilize high-RPM crank harmonics.

Valve train upgrade
Install non-AFM lifters (Delphi LS7, equivalent, or tie-bar lifters, fresh guide trays (if LS7 lifters), a new valley cover, and high-quality Multi-Layer Steel (MLS) head gaskets.
Secure cylinder heads using ARP Head Studs instead of factory torque-to-yield bolts.
Stealth/Smooth Idle Supercharger Camshaft with an upgraded fuel lobe (+32% or +38%) and a wide Lobe Separation Angle (e.g., Texas Speed F-117 Stealth, BTR Gen V Stage 1 Supercharger Cam, or equiv).
.660" Dual Valve Spring Kit with titanium retainers, hardened 3/8-inch pushrods, and a micro-polished rocker arm trunnion upgrade kit.
Upgraded timing chain
OEM water pump replacement.

Fuel System Upgrades
Install a remanufactured/new GM LT4 High-Pressure Fuel Pump (HPFP)
Install a matching set of GM LT4 Direct Fuel Injectors.
Install an upgraded low-pressure drop-in dual fuel pump system (e.g., Fore Innovations, Walbro, or equiv).

Misc
Install Smoothboost electronic bypass valve & controller.
Tune accordingly. It was suggested to me by my trans-builder that the shift points should be set to 7150rpm to cover for the delay.

I will be handling the cost to send the blower back to Whipple for maintenance & the additional pulley/install.
I will be handling the cost to ship the Mechman alternator back to get re-pullied to support the 7500rpm.
I will cover the cost for an upgraded throttle body.
I already own HP tuners MPVI3 andECM and TCM are unlocked.

There was talk in several forums of upgrading the crank bolts to ARP as well. Should I also be considering having the rotating assembly balanced? Roller rockers? An oil pan with baffles to prevent oil starvation during cornering? No room in the budget to convert to dry-sump. I don't think I am going to have the budget for a forged rotating assembly either - that's a pipe dream with 2 mortgages and 1 kid still in college. Am I missing anything else?

I like the "uniqueness" of keeping the 5.3.....Or should I skip all this ******** and just get a pulled LT4 out of something and do the low-side fuel upgrades?

 

[pronstar]

I would look into a GM crate L8P, 6.6L, nearly plug and play with 525 hp at the crank, for $9k-ish…then put your blower on that if you want more power.

It won’t give you the rpm but it’ll give you all the power.

L8P Crate Engine 523hp 543lbft

Check out the deal on L8P Crate Engine 523hp 543lbft at GM Performance Motor

www.gmperformancemotor.com

 

[Joseph Garcia]

^^^^^x2^^^^^

IMO, a lot easier and more dependable option, than trying to achieve and maintain a 7500 rpm motor mod.

 

[fozzi58]

@Joseph Garcia @pronstar

I've been considering the crate motor as well but my issue is the short redline. I find myself hitting the rev-limiter in 2nd gear during most AutoX events. Courses are usually short, with lower top speeds so I keep it in 2nd the whole time. With another 1000-1500 rpm, I can finish the "long" stretches without hitting the rev limiter.

Additionally, with the looser converter, I'm only getting 3000 usable RPM range between shifts. Not having paddle shifters makes it even more difficult - trying keep the wheel turned in the corners with one hand and find the stalk to hit the shift up/down button is frustrating and a higher risk.

I'm twisted up between what I want the truck to do vs what my budget will allow for.

Yes, it would be a lot cheaper to buy a 4th gen F-Body for 7 grand and just go racing...but where's the fun in that!

 

[Dantheman1540]

Have you looked at a blower spin calculator? The harder you spin a blower the hotter it will get. Typically people over spin them with a tiny pulley but adding 1,500rpm of power band could do the same. Atomic Fab and Perf used to have a great one, might be worth looking for.

I have had a 7k rpm SBE 6.0 for 5+ years now and it has seen hundreds of 7k shifts and bounced off the limiter at 7k plenty of times. But tbh it kinda scares me and I don’t think I’d ever want to hold it that high for long. Especially if blower temps aren’t in check. I think timing chain is one of the most important things, and I can’t remember what I have I’ll try to look it up but it was the top dog at the time for single chains.

 

[pronstar]

The racetrack / AutoX angle is tough.

A high rpm screamer in a heavy street truck doesn’t sound enjoyable to drive.

Have you considered a small gear change (slightly taller/lower numerically) so you aren’t bumping the limiter in 2nd?

 

[West 1]

Rebuilding the heads with new exhaust valve seats would be high on my list. The factory stock heads are known to drop seats out if exposed to higher than normal heat. A blower will certainly add heat. Make sure the machine shop knows what you plan to do. I had my Escalade 6.2L heads done and they used .005 interference fit valve seats. I think the factory seats were .003? not positive on that but the machinist I used is a friend and he said the .005 was plenty and I would never have an issue.

Add me to the list of people saying why Rev to 7500? Yep you can make HP up there for sure. The stress inside the engine block more than doubles between 6K and 7K, I bet it doubles again going to 7.5K.
You have a blower your torque numbers should be fantasitc? Maybe 600 foot pounds if you do this right. Torque gets your heavy beast rolling. Personally I would want huge torque between 2000 and 6000 and call it a day.

I have a old 66 Corvette basket case I am building. I built two engines for that car. A 327 with big AFR heads that will run out to 7500 RPM. Might make 425 HP but torque will probably be under 400 ft pounds. With a 4.11 and a 4 speed it should be fun to drive, also built a 406 with AFR heads to impersonate a Big Block, it has a cam that will be all done at 5,800 RPM but should make 450 HP and over 500 ft pounds of torque. I can switch engines pretty fast in that old car so each should be fun to play with but totally different experience. Keep in mind this car weights 3200 pounds, not 6,000 Pounds. Build the engine to haul the load you pull and you will be happier.

 

[fozzi58]

I have some time to decide in which direction I wish or should go. Good education on block stresses - didn't think of that. Same for valve seats.

The L8P is a much more economical way to go and will be well over 600wheel, even with the 8lbs pulley.

I just feel like that short rpm range is going to force me to shift a lot more. If there was a way to get paddle shifters mounted properly to the steering wheel, I'd be a lot more confident. There's no adapter for our columns to go to the 6 hole wheel which would accept pretty much any major steering wheel - even a late model vette or camaro steering wheel. Been looking since last summer.

Otherwise I am going to have to hack my wheel up, or pick up a bone yard wheel, to try and get a test fit to work.

The racetrack / AutoX angle is tough.

A high rpm screamer in a heavy street truck doesn’t sound enjoyable to drive.

Have you considered a small gear change (slightly taller/lower numerically) so you aren’t bumping the limiter in 2nd?

No one regrets going to 4.10s more than me. The factory 3.08s were way too tall but I should have considered 3.73 or even 3.55 when I did the rear. My mistake was not to compare final drive ratios in my transmissions. I upgraded to 3.73's in my TA and it sits at 1900rpm at 80mph....but that's the T56 manual. I took it for granted that the final drive ratio was about the same. Boy was I wrong...Silly rabbit.