corvette_bob

What woould happen if we could enlarge the stock plenum?
If the EGR valve was gone, expand the bottom of the plenum downward
and gain more volume.
The whole idea behind the SuperReam is to increase plenum size.
What if we do it another way?

TIMSPEED

Stealth Ram? Or at least it would look closer to it. The MiniRam/LT1(4) intake is a big plenum with short runners, while the TPI is a thin plenum with long runners. It's Horsepower Vs. Torque...too bad we can't create both. :D Go for it though! Fab up one and market it and make millions.

vader86

If you enlarged the plenum? Youd still have those long runners leaving from the same place right?

If you could enlarge the plenum and change the shape of the runners, to make them shorter, that would work for some more HP.

65Z01

The Super Ram effectiveness isn't so much a matter of larger volume but of shorter total runner length.

Shorter runners means better breathing at higher RPM so more HP, along with some loss of low end tuning efffect so loss of low end torque.

damionvoss

Just make sure to give all of your forum buddies a good deal! :yesnod:

bill mcdonald

I think the whole idea behind the superram was to get shorter runners. The bigger plenum came as an added bonus/natural design.

I want to see someone make a super ram clone out of a stock TPI by cutting the runners in half, and using 2 stock plenums for the plenum top. this way you would also have 2 throttle bodys. :crazy: :jester

if I only knew how to weld. :crazy:

dtorc4

Hey, I'll try anything if somebody wants to fab something up. I'm not using an EGR and the engine is not in the car yet. I just got the intake on today, so if you want to send something my way, I'll give you my address. :D :cheers:

KYVette90

How would you be able to put it all together once it is fabricated? I might be wrong but I think you would lose a crap load of torque if you had two throttle bodies on there. The superram is bigger but it still uses only one throttle body. You would also have to rig up something for the IAC on the second throttle body. To tell you the truth I don't think you could fit two stock throttle bodies under there and make it work. :cheers:

corvette_bob

Here's the reason I started this topic;


A while back, I called Lingenfelter Perf.
The guy I spoke to said the main drawback with
the stock plenum was the small amount of volume it
contains. I remember asking about the runner length,
and his answer was that the plenum size of the SuperRam played just as big a part as the shorter runners. LPE's goal was to increase plenum size
more than it was to shorten the runners. They knew that shorter runners would reduce low-end torque, but the plenum volume greatly enhances higher RPM use.

My thinking behind the increasing of plenum volume is to try to get more
RPM while retaining the runner length for low-end torque.
I know this probably won't even come close to a SuperRam, but it might be a good low-buck way to get a few hundred RPM from a stock "appearing" TPI.


[Modified by corvette_bob, 1:59 AM 9/25/2002]

bill mcdonald

Now that is very interesting. Who was this person at LPE that told you this?
I know they do the larger plenum on the modded ZR1's.
I say give it a shot if you like to.

So I am thinking now. A miniram probably has a smaller plenum then a TPI, but it only has 3" runners.
A super ram cuts off a few inches of runner and gets a huge plenum.

It seems to me, you would need a bigger plenum then the super ram to get 22" of runner to take effect of having more air in the plenum.

BIG JIM 54

I have posted this before but according to the book, "How to Tune and Modify Chevrolet TPI Engines" the first place to better performance, even on an otherwise stock engine is the intake system. The book suggests larger runners and base manifold. The book also says the TPI intake system was designed for a 305 C.I. engine and isn't big enough for a 350 C.I. SBC.

It would seem to me that increasing plenum size without bigger runners, better base manifold and a bigger throttle body and intake plumming would just put the bottleneck in another place without realizing much performance improvement.

FWIW,

BIG JIM

corvette_bob

"Now that is very interesting. Who was this person at LPE that told you this?"

It's been so long, all I can say is that it was one of LPE's tech/sales guys.

The Miniram has a larger plenum than TPI. Probably not by much, but larger.
One of the things I'm hoping to do is to put on a Accell base and some big tubes. I would think that there would be a max runner diameter as too large a tube would allow the loss of velocity thru the system.

Maximus9000

When you start messing with this type of induction your dealing with alot of differant elements. Induction pressure pulse tuning is what we have here, and runner length and volume, along with head port design, and plenum volume are all working in conjunction with each other to create a desired effect. The TPI system is designed to create low end torque. If top end is desired a whole differant system should be used.Since the heads are part of the equation they must be included in changing the characteristics of the engine. You'll notice that the really modified TPI engines on the forum have this done to them. Everything from the block up is differant. If modifications to the stock system are to be made it would make more sense to try and enhance the natural ability of the design and work on creating more low end torque, not top end HP and rev's.

89vette

The Miniram LT series intakes do NOT have big plenums. I bet the TPI intake is bigger.

Jason

corvette_bob

:smash: The Miniram LT series intakes do NOT have big plenums. I bet the TPI intake is bigger.
Jason

:smash:

:p: Oh Yeah?!?!?! :p:

Seriously, the MR just MIGHT have a smaller plenum than the TPI.
I was only going from hearsay info.
My original posting didn't consider the MR as it is a high RPM suited piece.
I'm more concerned with keeping low to mid range torque while getting a few more RPM in the deal.

fathermojo

does anybody have a photo or drawing depicting the inside of a stock tpi plenum? actually, maybe a better question is: does anybody have reynolds numbers and flow coefficeints for the plenum to runner transition? seems to me that the plenum size isn't going to make that much of a difference if the runners aren't redesigned to take advantage of the extra storage volume. just a thought

drive on dude!

JAKE

I agree. It depends on where the flow bottleneck is.

If the restriction is with the runners, then a larger plenum won't result in improvements, but if the plenum is the main restriction, the an improvement will be seen.

At that point, the focus moves to the next item on this list that then becomes the restriction: filter housing, MAF, TB, runners, manifold, valves, cam, etc.

Tuned Port means just that. Each component was designed to work in coordination with all the other parts and sized to "tune" the airflow to concentate power in the range desired by the engineers. Once you begin making changes, all their data goes out the window and you'll, in effect, start down the road of re-engineering the flow characteristics of the intake.

I like the idea though, since it will give the runners a larger reservoir to pull from. May do this to mine some day.

Thanks for the idea.

Jake

PeteL

Nah! Idea was to reduce runner length and increase runner diameter for improved breathing at higer rpm while trying to maintain some of the tuned port advantages at lower rpm.

The tuning of the TPI intake was a major advance at the time for fuel injection, similar to tuning the exhaust with long tube headers. Increasing the plenum with those long skinny runners will not accomplish anything. Reducing runner length and increasing diameter will move the torque curve up if the proper cam and tuning is applied. At some point you get to the LT-1 intake which has shorter runners then most high performance carb manifolds, with little peak effect, but huge high rpm flow.

The peaky effect of the tuned port is great fun on the street, the plenum is not THE limiting factor. As posted above, it's a system.

Mopar and some customer builders used long tube runners with no plenum years and years ago on carb big blocks and did manage some tuned effects and hugh low end improvements; too bad with a carb the engine had some real hard cold start problems (advantage to injection as the fuel enters near the intake valves}.

According to Lingenfelter's book, the size of the SR plenum was to do with allowing smooth transitions to the large runners.

corvette_bob

[According to Lingenfelter's book, the size of the SR plenum was to do with allowing smooth transitions to the large runners.]

I stand corrected

fathermojo

hmmm.... from what i've been able to gather from reading this thread, and let me know if i'm wrong here....it appears that low end torque goes away with short runners due to airflow not having the distance required to to trip turbulent flow to laminar? If i remember from my fluid dynamics classroom days, you need about 8 diameters of ducting to recover from turbulent flow after coming out of a hard bend so it would seem to make sense that ; a) at low rpms, the reynolds numbers are low and because those values are low, they won't get you into the laminar flow region where you have good flow characteristics at the boundry region of the runners and it follows that; b) at high rpms you regain the torque because your reynolds numbers get into the higher mach numbers and laminar flow doesn't make that much of a difference.

If anybody wants to shoot me on this, I'd be happy to be corrected

drive on dude!

86 L98 recovering from bubba surgery :chevy