I know that this has been addressed before, but it's been a while and I'm curious to see if any new research or data has been acquired. I'd like to know how big we could go, displacement, cam, head, etc. before the factory intake starts to hold us back. It's obvious that the TBSS or FAST LSXrt are proven improvements, but you know how it is when money's tight.

I was looking through the Comp Cams Master Reference Guide that my pop gave me (this book is awesome btw ), and I like the specs of the 273Lr HR12, which is ground on LSr lobes for cathedral port heads. Comp lists it as a 4.8-5.3 cam with a 1700-6800 RPM range, but I was considering it as a DD cam for my LQ9 (wish that I had the dough to build it so I could stop dreaming up different cam ideas for it lol).

Anyway, the specs are 223/231 .610/.617 112, and Comp states that it needs aftermarket airflow improvements, both in and out. I already have WCCH StageII 317's, but curious if the factory intake would leave too much on the table or not...

Feel free to discuss

 

imho , im no expert but i think a six oh will benefit from at least a tbss mani and for the mula its well worth those so calle 15 to 20 rwhp , bud have you looked into ma new cam 228/232 612/600 111+3 lsa , i think it will work great on you lq9 build that you WILL! finish sometime soon ,

 

Thanks Eric, I keep praying to win a lottery or get an inheritance from a long lost relative so I can put this thing together lol The TBSS intake is definitely a bang for buck mod IMO...

 

hmmm i was wondering this too. i have a simple of the shelf 224r cam and have the stock heads n mani right now. I was planning on prc 2.5s and lsxrt and was wondering how big the gain will be. i might be able to pick up a tbss manifold cheap locally if i dont feel like dishing out the cash for the FAST. Also, how big of a throttle body do you guys think we should go on a h/c/i 5.3? Is the 102 overkill on a 5.3? I am thinking about spray and more cubes later....im not trying to threadjack Bud, just fueling the fire lol

 

That's cool, I'll take as much info as we can get

I know that the FAST LSXrt showed gains across the entire RPM band when bolted to a stock 5.3...can't remember what size TB was used though. Pretty sure that the dyno graphs were in this section somewhere...

 

From what I been gatherin from peoples setups is that the tbss matches well with proper head cam on 5.3 while the lsxrt is liking the bigger cubed cam/head setups just an observation. I know grey matter 04 put the tbss intake on his cam only 5.3 and he said it lost power replaced it stock and it picked back up. Also heard a few times the lsxrt if matched with a 102 TB take some time to get the tune down because it flows so well. Don't jump to conculsions this is just what I have heard/read in other post I am NO expert

 

This is the thread that I was referring to with the FAST LSXrt dyno graph, it was on an 07 GMT900 which already has the TBSS style intake. They reused the stock 90mm throttle body, and the two intakes were fairly close below 4500 RPM, but above that the FAST intake took off, gaining 20.5rwhp at 5500 RPM!

https://www.performancetrucks.net/fo...ast+lsxrt+dyno

4500 +3.5rwhp
5000 +17.3rwhp
5500 +20.5rwhp
6000 +19.8rwhp

 

I'd put a 102/102 FAST setup on a 5.3 in a heartbeat

 

If I had the dough, so would I

 

Well thanks alot billy, thanks to your wonder full random postings now i want a fast. who wants to buy a tbss cheap..billy?