I was recently at a chevy dealership with a buddy picking up his wifes new cavalier and I was browsing through a corvette dealership pondering weather I should put corvette emblems on my Trans Am to screw with people. I saw sticker that said LS1 350 Tuned Port Injection. I thought the LS1 was different from the TPI could this be a mislabled sticker???

 

It's not "TUNED PORT INJECTION" but the LS1 has Induction that uses Tuned Ports.......

So yes, it's is a form of induction that is tuned, but it's not your dad's TPI....

Get it? Yes it's Tuned Port Induction, but it's not TPI ...? Ahh screw it

 

350?

LS1's are not 350 CI.

 

346's

 

I can see how this discussion went in the design room:

Bob: You know Steve, the LS1 is only 346 cube inches...

Steve: Well Bob, that would give it about the same displacement of empty space as your wife's "Woo Hoo"

Bob: I know, I can get my whole golf bag in there; but back to the point Steve.

Steve: Yeah, but Ford guys don't know any different... they put 5.0 badges on cars with 4.9's under the hood...

Bob: I guess if it's okay that they round up to 5.0, we can round up to three-fiddy.

Steve: Now back to your wife, don't I owe you $5, and when is her sister avaliable?

 

The LS1 design is a form of Tuned Port Injection, it uses the same concept. But it is not TPI.

 

WHOOPS! Your right, it said LS1 5.7Lt Tuned Port Injection. My bad.

 

Oh they circumvented it.

I've actually seen a LS1 350 sticker before, I laughed. A lot.

 

TPI = Tuned Port Injection, a marketing name/term used on GM F and Ycars from mid 80s to early 90s.

The name implies acoustically-enhanced cylinder filling of the same type used by the Ramchargers in the late 1950s and early 1960s... and many others since. The LS1, among several GM engine intake manifold designs use the same concept BUT they don't always use the same marketing term. There were some 3.8 liter v6 GM engines that did use the TPI term (either as TPI or spelled out).

So when you ask the question you have to be specific, either concerning the engineering principle used on an engine (LS1 uses TPI acoustic tuning) or concerning the marketing name attached to it (LS1 is not called a TPI engine by GM). In the case of the LB9 and L98, the 3rdgen Fcars, the engine uses both the engineering idea and was probably where the marketing name originated. HTH.

 

LT1 and LS1 intakes aren't technically classified as "tuned setups". Sure, they are designed to meet certain criteria but they aren't considered a true tuned design.

 

Shifty, I'm curious to know what drives you to say that about the LS1 intake?

In 2001, when GM started putting the LS6 intake on all LS1's as well - they also changed the valve timing events to better match that of the LS6 intake's resonance, than of the smaller runnered original LS1 intake. In other words, they changed the cam profile slightly to ensure that the "Pulse Effect" was occurring well within where it should be to ensure proper performance. Without the cam changes, the valve timing would have been off track of where the intake pulse resonance was greatest, leading to a untuned combination.

Why would GM change the cam along with the intake, if the intake was not specifically tuned for only one operational range, but to only act as a shell for adequate performance from point "A to B?" I'd have to say those runners are the diameter and length they are for a very specific reason and not by accident, with the total grass roots start of the LS1 design.

(I can't post solid duration numbers yet, but I know they increased intake valve lift by .06mm or .024in - I'm still digging for the duration numbers, but it's obvious that this was a deliberate tuning measure.)

The LT1 was obviously an attempt to remove that effect ... no argument there. I just feel it would be an injustice to say that GM didn't tune the LS1/LS6 intake to resonate in the 4200-4800 RPM range. (depending on intake)

 

People bash on the Tuned Port all the time and here they are calling the *** Chosen LS1 a Tuned Port, if it wasn't for the L98, where would it be

 

The only reason people bash the tuned port is because you can't get air through 21+ inches of runner and into the ports quickly enough at high RPM's. Shorten the ports, enlarge them, and all of a sudden the system becomes the idle street machine... some unknown guy (sarcasim) did that with an intake meant to be "What GM should have done for a sports car and not a truck" and built that little SuperRam....

Tuning the intake is great, it's just a matter of what it's tuned for. Our TPI intake's aren't tuned for modern sports car requirements, but are tuned great for making a 305 generate near 350 CFI low/mid range torque .... it's what the system was meant to do, same torque out of less displacement. If the peak torque requirement was aimed to be around 4,000 RPM and not 3,000 it would be a whole different ball game (and intake).

 

Taste... (torque) great and less filling !

The design has evolved from several generations of the "original" TPI setup. They've learned alot by playing with runner diameter,length and timing of the intake/exhaust events. Still comes from the same heritage so why not classify it as a "tuned port", It is designed to operate in the same manner.
Looks goofy though

 

I think our friendly gen1 SBC 350 is actually a 349.87 or something....right? if ya wanna get cranky!

 

JP86SS - Strongsville huh? I'm just up 71 off 150th .... Small neighborhood.

 

For those really interested, read the book Scientific Design of Intake and Exhaust Systems by Smith & Morrison. It's all about acoustic effects on cylinder filling and scavenging. It's not a new book but none of the concepts have changed --- except for the modern variable-length and variable-volume intake manifolds. Anyone reading it will understand better how TPI works, and how the same concept was applied (in a better fashion) on the LS1 engine, among others.

Smith & Morrison's book has been discussed here on TGO, in other threads, if you search for them. HTH.

 

Yup you are correct. After I posted I went back into some of my literature and realized my error.

 

yeah on my window sticker for the 2001 ss it says 5. liter alum v8 engine 346ci

 

It's just the same thing the motorcycle industry has been doing for years.

A 500 can be a 490cc, 480cc, 498cc, 501cc, 505cc, etc.

It's all marketing really. perhaps they think 350 sounds better?

-- Joe

 

Probably. Kinda like the HP ratings, nearest 5 or 10 is close enough. Although I did notice the new GP GXP and Impala SS are 303hp.

 

whats closer to "5.0L"......302 (ford) or 305?

 

305

 

The new LS7 "427" small block used in the new ZO6's is really a 428. They call it a 427 for nastalgic reasons.

Kevin

 

what did the 427 go into? chevelle? or is that 455?

 

The 427 went in the corvettes. And the 455s went into Buick,Olds and Pontiacs.

 

what years did the vette use 427?

 

Found that book about four years ago after asking about it on here. Very good book.