Jump to content
Sign in to follow this  

Motor Guidance Needed.

Recommended Posts

Okay, so I have been doing a LOT of reading on this site and others in regard to engine performance, upgrades, power and drive-ability for my Silverado SS. Quite frankly there is SO much information it can be quite daunting and confusing for someone such as myself; as I am a do-it-yourselfer with little knowledge in what I am looking to do. So please bear with me.


My truck is a 2003 Silverado SS with 62,000 miles. It is in near perfect condition, always well maintained and has been stored in a climate controlled garage for the last 5 years or so. I do NOT drive it everyday.


The only current modifications are:

Long tube headers

Custom 2 1/2 Borla Dual Exhaust (with X-pipe)

Cold Air Intake.


To make a long story short, I want more horsepower and Torque. I would love to have somewhere between 550-600hp at the crank with respectable torque numbers.


I am considering the following:



4.03 pistons -11cc Dish

6.125 Crank

247cc,68cc heads

cam choices are as follows:


Intake Duration 212 224 216
Exhaust Duration 218 230 220
Intake Lift .558 .581 .56
Exhaust Lift .563 .591 .56
LSA 115 114 114

2800 Stall (?)


What do you all think? Is 550-600 hp achievable on this setup naturally aspirated and yet still be able to put on a supercharger at some point in the next few years without going back in to the engine?


Please keep in mind that even though this is NOT a daily driver, it still needs to be considered a daily driver. I don't want some crazy lopey engine. I need to be able to jump in it and drive it across the country, or pull a small trailer (6 1/2 ' by 12 ' single 3500lb axle) or my wife needs to be able to jump in and drive it to work, etc. It will likely never see a race or drag strip.


I have considered putting on a Radix or Whipple on the stock 6.0 instead of building an engine. However, I just don't believe I will be satisfied with the outcome.


Your guidance is really appreciated.

Share this post

Link to post
Share on other sites

Since no one has bothered to help, I'll chime in and give my opinion. First off, it sounds like you have a very nice, unmolested SSS on your hands. So for that reason alone, I wouldn't go the 421 c.i. route if it were my personal truck. Or any stroker for that matter, unless it already needed a rebuild. I would however look into some form of power adder and without a doubt a 4L80e swap. With the correct heads/cam/blower setup you could definitely be within your desired power range, it would be much more streetable and retain some pretty good towing capabilities.


IF you do decide to stay N/A and go with a stroker, for cam selection I'd suggest talking to a few cam vendors such as Cam Motion and Martin Smallwood. They can spec a more suitable cam for your setup that will maximize power and driveability. I understand you want to keep it streetable, but the three cams you listed above all seem far too small to me for a 421 c.i. motor.


I personally think you'd be much happier with a blower on the 6.0L with a nice set of heads and cam to compliment everything, a 4L80e and a good converter.

Share this post

Link to post
Share on other sites

Thank you for your reply and suggestions zachm89. I was beginning to wonder if I posted in the wrong section or what!


I really like the idea of keeping the original engine a 6.0 and doing a blower (radix or whipple). Mostly just for the street-ability. From what I have researched and been told, if I ONLY do the blower, I can expect right around 465hp/450ft-lbs at the crank. This would be well short of my goal. Now, from what I understand, if i do the blower, cam, and heads, I should expect more hp and tq, but I have not been able to determine how much. So do you think with a "streetable" cam and heads I could shoot for 585hp/450ft-lbs? If so, can you (or anyone else) give a recommendation for head and a cam?


Now, if I decide to keep it NA as a stroker, with the specs listed in my original post, I have had different cam recommended. This one is 228/228 duration, .600/.600 lift on 112 lsa. I have been told with this cam, on this stroker, with a 3000, stall, I should be at 585hp minimum using a conservative tune. And still be very drive-able with a little lope at idle.


I have to keep my total budget at NO MORE than $10k. This would include doing all the install work myself (with the exception of tune- likely blackbear mail-order). For example, if doing the stroker, I would buy a complete short block and install it in my struck using all my oem components (wiring, coil packs, injectors, etc). If doing a blower/cam/heads, then I would install all of that on my stock 6.0.


I will try to post a pic of my SS in a little bit.


Thanks again BTW!

Share this post

Link to post
Share on other sites

Any other seasoned experts have any advice?


Sounds like you are on the path to build :) . As zachm89 has stated a 4L80 or 6L90 swap will be ideal to get all those ponies to the ground.

Share this post

Link to post
Share on other sites

Join the conversation

You can post now and register later. If you have an account, sign in now to post with your account.

Reply to this topic...

×   Pasted as rich text.   Paste as plain text instead

  Only 75 emoji are allowed.

×   Your link has been automatically embedded.   Display as a link instead

×   Your previous content has been restored.   Clear editor

×   You cannot paste images directly. Upload or insert images from URL.

Sign in to follow this  

  • Create New...