454 (7.4L) swap / repair options - 1999 Suburban K2500

Disclaimer: Links on this page pointing to Amazon, eBay and other sites may include affiliate code. If you click them and make a purchase, we may earn a small commission.

L29Sub

I'm Awesome
Joined
Jul 31, 2013
Messages
234
Reaction score
120
Any easy mods to get more flow out of them?
They flow plenty as is. Increasing flow, beyond matching ports, will create no benefits for towing. And don't polish the runners.
454 mods are not after high RPM.
Anyway, "porting" truck heads is pointless.
Gotta focus on towing. If you want a screamer, go with light truck, and forget towing. Can't have it all.
Don't apply SB tuning theory to a BB.
Think 6500 lb Suburban...

Sent from my SM-G965U using Tapatalk
 

Supercharged111

Truly Awesome
Joined
Aug 20, 2015
Messages
12,615
Reaction score
15,241
They flow plenty as is. Increasing flow, beyond matching ports, will create no benefits for towing. And don't polish the runners.
454 mods are not after high RPM.
Anyway, "porting" truck heads is pointless.
Gotta focus on towing. If you want a screamer, go with light truck, and forget towing. Can't have it all.
Don't apply SB tuning theory to a BB.
Think 6500 lb Suburban...

Sent from my SM-G965U using Tapatalk

I'm thinking in its 2500-3500 RPM happy place it's flowing a lot of air so gains in airflow would easily be realized there.
 

LC2NLS6

I'm Awesome
Joined
Apr 23, 2019
Messages
272
Reaction score
225
Location
MI
Subscribe to motortrendondemand and watch EngineMasters. And follow Richard Holdener on YT. Draw your own conclusions from actual tests. Myself? I say get best heads you can afford, smallish cam, turbo(s) and Holley EFI.
 

L29Sub

I'm Awesome
Joined
Jul 31, 2013
Messages
234
Reaction score
120
I'm thinking in its 2500-3500 RPM happy place it's flowing a lot of air so gains in airflow would easily be realized there.
The functional RPM range with 4:10 and OD is about 1500-3000. 3000 in top gear will be 85-90 or so. 'Burb don't happily go that fast.
3500 is easily doable, but the truck will require major changes in order to operate at that RPM.
Keep in mind that Vortec '96-'99 have much better heads than did
'95 and down.


Sent from my SM-G965U using Tapatalk
 

Supercharged111

Truly Awesome
Joined
Aug 20, 2015
Messages
12,615
Reaction score
15,241
The functional RPM range with 4:10 and OD is about 1500-3000. 3000 in top gear will be 85-90 or so. 'Burb don't happily go that fast.
3500 is easily doable, but the truck will require major changes in order to operate at that RPM.
Keep in mind that Vortec '96-'99 have much better heads than did
'95 and down.


Sent from my SM-G965U using Tapatalk

Yeah I forgot this was TBI. 2500-3500 speaks more to the Vortec. It's not a dog below that, but it makes the most at 2500-3500.
 
Joined
Sep 13, 2020
Messages
11
Reaction score
7
Location
Iowa
Knowing the big block engines aren’t built for high rpms and the 454 has had multiple issues through the years. If your not worried about mileage there’s 100’s of ways you can go. In my opinion hp don’t pull weight. And higher rpm’s can do more harm than good. I mean a 13 hp Kohler lawn mower engine will power a 2500lb car. (That’s a fact not opinion). I’ve seen it. My point is you can throw all the money in your wallet at it and get ungodly amounts of horse power. Just remember the higher rpms with a big bore and a long stroke are a good way to break stuff. In my experience between the right set up with trans and diff gearing you can pull comfortably with a 5.3ls. Obviously you want your heart and soul of the vehicle to be sound. But if it was my truck I’d be looking more into tires, suspension, and gearing. The can be the best engine in the world but with out these other four components set up correctly the work loaf will win every time. Good luck. I’m currently building a 96 gmt and swapping in a 6.0 with a new trans and gearing set up. Suspension to.
 

L29Sub

I'm Awesome
Joined
Jul 31, 2013
Messages
234
Reaction score
120
Yeah I forgot this was TBI. 2500-3500 speaks more to the Vortec. It's not a dog below that, but it makes the most at 2500-3500.
Be advised that a K2500 at 2500 RPM in OD and 4:10 rear is traveling about 80 MPH.
3500 offers 103 MPH.
Pulling at 55-65 MPH you'll range 1700 to 2200 and this is where you want, at the least, be well into the cam torque curve.
In no way would you aim at a "2500 to 3500" torque peak. Operating in that high RPM range would require 3rd gear on every knoll when operating at normal speeds

FWIW:
Input Parameters Are the Following:

Differential Gear = 4.00 to 1

Transmission Gear = 0.75 to 1

Tire Diameter (Inches) = 31.00

Vechicle MPH = 60

Computation Results:

Computed Engine RPM is 1952

Critical thinking will save time and material, and prevent disappointing outcomes.

Sent from my SM-G965U using Tapatalk
 
Joined
Dec 9, 2019
Messages
3
Reaction score
0
Location
Carlton Oregon
The problem with smog 454's is low compression. Every point of compression adds 50-75 HP in a BBC. A proper BBC will rev to 7K if you want it to but that doesn't make it a good tow rig. Torque is your friend. Build for torque.
 
Top