TreyZ28

The 4.8 5.3 and 6.0 have cast irons and are using primarily in GMs trucks. They also use Votex heads but are interchangable with LSx heads. 6.8 with LS6 heads anda Z06 cam would be one TAME fast car :bow:

CarAteMyMoney

What about the fuel system? isn't it returnless? and with an internal regulator in the tank.. how would you plumb that?

antenna

Z51Racer,
Where did you go?
What are the real numbers to plug into the formula?

Jussi

Guys guys...

Please don't use the helmholtz equation to calculate the optimum intake length!!!

Its way off....sorry... the situation in intake manifold is much more complicated/dynamic than that.

The guideline or basic starting point for intake lenght is one that produces a pressure pulse at intake valve closing...and that of course depends highly on the camshaft and rpms used....usually engineers aim the second return pulse to arrive on the intake valve at desired highest torque rpm....

All this is also affected by exhaust tuning.... meaning there is no point just tuning the intake if you have no data on exhaust pressures...


The simpliest way to estimate the intake tuning length is to buy a engine simulation software like wave, dynomation or virtual 4-stroke...

Even a relatively cheap software like engine analyser pro will give you much more accurate results than Helmholtz equation.

Just my 5cents as a engine engineer...

Jussi

antenna

The way I remember it is that you want to tune the intake to provide the reflected positive pressure pulse just before the intake valve closes.

The cam overlap lets the exhaust scavange not only the exhaust gasses but also some of the new charge. The exhaust then provides a reflected positive pressure pulse to push some of the charge back in.

The other thing I remember about this tuning is that it only works for about 500 rpm. Pick where you want the 500 rpm band to be.

This tuning will also provide a flat spot somewhere. There will be a point where all the tuning adds up in the wrong direction.

I'm not sure that this kind of tuning will really be possible or even desirable for a street engine.


[Modified by antenna, 7:41 PM 4/15/2003]

CorvetteZ51Racer

As an engine engineer doing R&D in NASCAR, and coming from the same training that the engineers who developed the C5R engine did, I can tell you that, short of having WAVE at your disposal (which I do, BTW, but it's a $30k/seat program, plus the $50k or so in DAQ equipment necessary to get the IMEP data necessary to create a WAVE model that means anything) the Helmholtz gets you awfully close. Actually, I just finished the design phase of an L98 replacement intake manifold using the Helmholtz criterion, and when I built a model in EAPro to simulate the engine and my intake manifold, I could not get a better power band through fiddling than I did using the Helmholtz equation. The manifold design that I came up with using those equations (and other things I know about intakes...that's my area of research, BTW), shows a HUGE gain over the stock TPI setup, as well as a significant gain over the SuperRam on an essentially stock '87 L98 motor (again, in EAPro models).

TreyZ28

I dont remember if I sent my paper to those guys who wanted it, but here it is


I wrote it for my Comm 101 class so it was VERY general and watered down. The first time I handed it in she said it was too technical and I almost failed. I had to skim it down from 50 pages, but if you want it, here it is
http://web.camaross.com/forums/showt...ighlight=paper

I had one typo-
Gen I went to a 1 peice rear main, not two peice in the 1980's

It is a good general answer to the "whats so specail about the LS1" question.

Again, very breif and watered down.

And just some FYI, as it looks now I'm losing $13,000 in financial aid because this prof lost one of my papers and almost failed me even though she openly admits that she lost it.
If i had known she lost my paper and was going to fail me, I never would have wasted my time writing this one. She told me 5 weeks after she lost it though :rolleyes:

SonnyinVA

wow!
i might as well stop spending money on my junk LT1.
plus, i have just been reminded that i don't know diddly!!

glad there are guys like you out there figuing this crap out so i don't have to. hahahaha
:cheers: :cheers:
actually, it is very interesting to read this technical stuff even tho i have never heard of it before.
see ya,
sonny

antenna

CorvetteZ51Racer,
Glad to see you back, You must have missed my request for some data.

Let's give the Helmholtz formula a little demo. You must know some of the values that we can use for the volume, length and area. Let's put the values in the formula and see how it gives the 7" that you said.

You must use the WAVE program all the time. You probably know all this off the top of your head.

Let's give a demo of how you do this head/runner design.

antenna

I looked at your paper. I picked out these problems. Do you see what I'm talking about?

This made most the crank shafts was a particularly attractive

Between 1974 and 1976 a slew of emission controls products.

The LT1 utilizes special hypereutectic pistons, a high silicone and iron mixture, for its light weight.

The lighter pistons allowed for a rotating assembly, but prevented crankshafts from being swapped in the late model Gen I 350s.

CorvetteZ51Racer

Give me a few days. The next couple of days are going to be VERY hectic, and I will hardly have time to eat! Over the next 5 days, I have two PhD tests to do, a prototype intake manifold to build, and a pair of brake calipers to CNC, not to mention conference calls for my research! As a matter of fact, I just got back from shipping and receiving...there's nothing like opening up a few boxes and finding several thousand dollars worth of engine parts you get to play with that you don't have to pay for! :D

On the WAVE software, yes I do use it quite a bit. It's powerful software, but kind of a pain in the butt to use. Ah well, can't have everything, right?

LS1Tuner

What about the fuel system? isn't it returnless? and with an internal regulator in the tank.. how would you plumb that?

I used the 97-98 Corvette Fuel Rails which has a return fuel system. Then just order the fuel rail fittings from :

company: Pure Choice Motorsports
web site: http://www.performanceplumbing.com
(could not find the part on their site.....)
part #: 5800
-6 AN Fuel Injection Fittings for GM LT-1, LS-1, and LT-4 engines $39.95 a pair (to and from fuel rail)
phone #: (888) 505-8355

They snap right into the fuel rail and give you a 6AN fitting coming off the rail, it also comes with the braided fuel lines and the fitting to cut off the ends of stock fuel lines from car and put AN fittings right on both ends. Boom your fuel system is hooked up in less than 30 minutes.

bill mcdonald

Can I see a picture of what $150.00 will buy for the mounts?
Also do you have any pictures of the LS1 in your C4?
You can mail them or what ever.
bmcdonald@px.com

Also, where in CA are you located?

CarAteMyMoney

thanks - what else should i know about the swap?

I'd like to eventually find a LS1 or Gen 3 v8 and swap it into either my vette, or sell the vette and start on a '37 Chevy

antenna

As soon as things calm down for you, I'd like to see how the formula works with the real numbers, or close to real numbers.
You posted the formula as;

n = c / (2*PI) * sqrt(A / (V * L))
where:
n = frequency in Hz
c = speed of sound in air
A = area of the resonant chamber (runner cross sectional area)
V = volume of the resonant chamber (volume of the runner and the port in the head)
L = length of the resonant chamber (distance from plenum to intake valve)

All I need is some typical values for A,V and L.




[Modified by antenna, 11:42 PM 4/16/2003]

Formula 94 LT1

Hey is it possibly to connect a t-5 up to an ls1 seems like that wouls save some significant weight... and be MUCH cheaper...

LS1Tuner

A t-5 would explode first time you powershifted it.

I wouldnt recommend putting a weak tranny like that behind it.

Marvolus

WOW WHAT A BUNCH OF BABY"S a LS engine is a totaly diffrent engine than the old small block it flows way more air even in stock form it will blow away most built small blocks with no more than a cam swap & a set of headers minor tuning of the computers fuel & spark curve will smoke all of your LT1's LT4's ECT & most BIG BLOCKs wake up guys this is the 2000's the old small block is the model T of chevy engines SPEND THE $3000 & SAVE LOTS LATER & you will pull down 20 mpg easily they make a mount for the AC or they also make a deal that you can notch the cross member for the AC pump either way this is the wrong place to ask about swapping a LS go to LS1TECH.COM those guys know whats up these guys are stuck in the stone age you may as well have ask BARNY RUBBLE about the swap as to ask here look at the C7 post will tell you how out of touch they are RAOTFLMAO..........!!!!!!!! I put a LS 6.0 from a 2008 caddy escalade in my 67 FIREBIRD BEST MONEY I COULD HAVE SPENT runs like a scared rabbit with it's A-- on fire & pulls down 25 mpg on the road you can bet a LS will be in my C4 before I put a dime in that small block it has now it's an easy swap !

Black89Z51

Do you realize you just dug up an 8 YEAR OLD post? LS1's were only ~6 years old when this came out.

dizwiz24

No crap. I guess someone above just wanted to talk some trash.

Forced induction, whether its SBC, LTx, or LSx is what works.