Another intake manifold question 1

[NickB]

I'm in the process of modifying an intake manifold for a Chrysler 2.2 turbo, basically the only thing left the same is the runners, the plenum has come off (plenum roof was 3/4" from runner entry, and was a VERY odd shape, can't be good for flow), injectors have been repositioned sligthly, porting/smoothing has been done etc...

What i'm looking for is some info that will show relationships between plenum volumes/shapes and how it will affect the torque curve. I'd like to get a torque peak around 4500 rpm. I've seen many different opnions on this, ranging from cylinder displacement to twice total engine displacement (.55L to 4.4L) I'd rather not finish this thing off and have it perform poorly.

Relevant specs:
Displacement- 2.2L, 135CI
Bore- 3.44"
Stroke- 3.62"
#cyls- 4
Rod length- very close to 6"
valve diameter- 1.45"
2 valves per cylinder, wedge type chamber shape

Runner length- 11"
cross section- 1.1x1.3 at head, 1.3x1.7 at plenum
intake opens @ 0 btdc, and closes 56 abdc
(cam duration may be increased later)
throttle body will be 2-2.2"

Running 18-25psi boost

nyone who replies, thanks in advance, your help is better than my guess.

 

[MaxRaceSoftware]

Nick,
the 1.1 x 1.3 (= 1.430)cross-sectional area @ head is very close

..could be a little larger to 1.466 to 1.544 area sq.inches

the 1.3 x 1.7 = 2.210 sq.inches area is about the largest area you want.

Your total intake system length should be = 16.400 inches in mid-port length

Floor Length
+ Roof Length
---------------
(Total * .5) = Mid-Port Length

Add your head's mid-port length to the mid-port length of the intake manifold runner and should be 16.400 for
4500 peak torque to 5900-6000 peak HP points

total induction CC volume should be 429.0 cc to 460.0 cc
not counting plenum area .

also you should be closing intake valve at .050" = 53.9 deg ABDC the 56.0 ABDC ? -> is a little late , but with boost it might work OK ?
my 53.9 figure is only for carbs, no-boost psi


Larry Meaux (meauxracing@mindspring.com)
Meaux Racing Heads
MaxRace Software
ET_Analyst for DragRacers

http://www.mindspring.com/~meauxracing/

 

[MaxRaceSoftware]

686.0 cc plenum volume would be a good starting point
thats .3111 x total cc engine size for 4 cylinder engine

4424 cc at twice cc engine size would be way too large for a 4 cylinder , ( 2 x cc-engine ) might be ok in single-cylinder , but not 4 cyl ???

i think after you went past 1106 cc plenum volume, torque/throttle response would suffer ..i'm referring to no-boost ...with turbo-boost psi , maybe not ?

Larry Meaux (meauxracing@mindspring.com)
Meaux Racing Heads
MaxRace Software
ET_Analyst for DragRacers

http://www.mindspring.com/~meauxracing/

 

[NickB]

"total induction CC volume should be 429.0 cc to 460.0 cc
not counting plenum area ."

Is that the volume of each runner, or all of them combined?

Any suggestions on the plenum volume?

The runner length was estimated centerline from the valve face to the plenum. If it's off by a half inch and it moves the powerband a few hundred RPM, i'm not going to worry about it at all. I'll try open up the small end of the runners, but i can't really get inside them to weld up the big ends, again, i'll just deal with it, as you said, it's about as big as they should go, it's not like their way out....

Thanks, i think i found my new favourite message board, the info in here is great!!!

 

[MaxRaceSoftware]

Additional Info ;

use 3M/Scotch 1/4 inch masking tape
cut a strip and tape on floor of cylinder head port
take a pencil or marker , and scribe a mark
across tape at valve seat lap-line ....then another
mark at head's intake port flange .....
pull out tape ..lay across table, take dial-calipers
and measure length ....do same for ROOF , being careful
around valve guide , and measure that length,
add the 2 together , divide by 2 = mid-port length
Larry Meaux (meauxracing@mindspring.com)
Meaux Racing Heads
MaxRace Software
ET_Analyst for DragRacers

http://www.mindspring.com/~meauxracing/

 

[NickB]

Thanks!!!!

 

[MaxRaceSoftware]

"total induction CC volume should be 429.0 cc to 460.0 cc
not counting plenum area ."

Is that the volume of each runner, or all of them combined?
--------------------------------------------------------

the 429 to 460 cc is the
Total_Volume = Cylinder_Head_CC + Int_Manifold_Runner_CC

Does NOT include the Plenum Volume

the plenum vol CC were calculated separately !

Larry Meaux (meauxracing@mindspring.com)
Meaux Racing Heads
MaxRace Software
ET_Analyst for DragRacers

http://www.mindspring.com/~meauxracing/

 

[MaxRaceSoftware]

Nick, its only for 1 intake port + 1 cylinder head port combo = 429-460 cc

doesn't included the "other" intake and head ports, plenum

Larry Meaux (meauxracing@mindspring.com)
Meaux Racing Heads
MaxRace Software
ET_Analyst for DragRacers

http://www.mindspring.com/~meauxracing/

 

[NickB]

That seems kinda small to me, but then, i don't exactly have anything to reference this by except what i see on production engines, and we all know they're not exactly optimised for performance.

So, what i'm gathering here is that the volume of the runners and the volume of the plenum are a function of the desired operating rpm range, and the displacement of each cylinder. Would the plenum volume increase with an increase in the number of cylinders? It seems that the two different volume are tailored such that they resonate in some fashion at the desired rpm range (making me think that plenum volume doesn't depend on the # of cyls), like a pair of springs and a mass suspended between them. So, i'm assuming that the two 'air springs' can be designed to resonate at slightly differing frequencies such that it widens the resonant peak, lowering the Q of the system. (sorry if i get too much eletrical eng. into this) Having the two frequencies dead on would result in a much higher gain at that rpm, but the operating band would be narrower.

If this is true, can you give me some ideas how to calculate the resonant rpm of both the runners and the plenum? Since i can't change the runners too much, i'm thinking i'd be able to select a plenum volume such that it would shape the peak of the torque curve where i want it. I'm thinking they'd operate like simple helmholtz resonators, but i'm not sure what ratio of engine rpm to resonant frequency is desired.

Thanks for your patience with me, i'm eager to learn.

 

[NickB]

I've got it all ready to go together. Th manifold is 12.5 inches across the 4 runner inlets, and i'll be using a piece of 3" tubing for the plenum. There will be a flat spot 1.8" wide whre the runners met the plenum, the volume will be approx. 72 ci, just slightly larger than the 1100 cc you recommended.

Any last comments before i weld it on?

 

[MaxRaceSoftware]

Nick,

did you "grind" a radius around each intake manifold runner
"entry" into plenum ??

you need at least a .250" to .500" max radius around runner entry

don't leave entries at 90 deg sharp edge around entries .
------------

the "flat-spot" is the "floor" of the plenum at runner entries ? Larry Meaux (meauxracing@mindspring.com)
Meaux Racing Heads
MaxRace Software
ET_Analyst for DragRacers

http://www.mindspring.com/~meauxracing/

 

[NickB]

I think pictures are in order here......

http://members.rogers.com/nickboers/100-1701.JPG

http://members.rogers.com/nickboers/100-1702.JPG

I'm making the fuel rail tonight, making the throttle body adaptor plate as well, might not get it welded tonight, i have things to do for some customers as well.

 

[evelrod]

Nick---I must say that is some NICE work there!!!!


Rod

 

[MaxRaceSoftware]

Nick the manifold pictures look great maybe one small problem is your injector angle might be too much

maybe could have aimed it straighter into port


from the picture it looks like its aiming too much immediately to port floor , it should still work though.

Nice welding/fabricating !!!

Larry Meaux (meauxracing@mindspring.com)
Meaux Racing Heads
MaxRace Software
ET_Analyst for DragRacers

http://www.mindspring.com/~meauxracing/

 

[MaxRaceSoftware]

REM ---------------------------< AC-BELT.BAS >
REM -------[ .BAS program to calculate air compressor belt length ]---------
REM -- use with QBasic or QuickBasic versions
REM -- can use to compute A/C , power-steering, alternator, etc. belt lengths

start:
COLOR 15, 1: CLS : COLOR 14, 1
LOCATE 2, 15: PRINT &quot;.BAS program to calculate air compressor belt length&quot;;
COLOR 15, 1: LOCATE 5, 5
PRINT USING &quot;Pulley center-to-center distance=###.### &quot;; cc
LOCATE 7, 5
PRINT USING &quot;Small pulley diameter (inches) =###.### &quot;; sp
LOCATE 9, 5
PRINT USING &quot;Large pulley diameter (inches) =###.### &quot;; lp
LOCATE 5, 47: INPUT cc$: IF LEN(cc$) > 0 THEN cc = VAL(cc$)
LOCATE 5, 5
PRINT USING &quot;Pulley center-to-center distance=###.### &quot;; cc
LOCATE 7, 47: INPUT sp$: IF LEN(sp$) > 0 THEN sp = VAL(sp$)
LOCATE 7, 5
PRINT USING &quot;Small pulley diameter (inches) =###.### &quot;; sp
LOCATE 9, 47: INPUT lp$: IF LEN(lp$) > 0 THEN lp = VAL(lp$)
LOCATE 9, 5
PRINT USING &quot;Large pulley diameter (inches) =###.### &quot;; lp

bl = (2 * cc + (1.57 * (lp + sp))) + (((lp - sp) ^ 2) / (4 * cc))

LOCATE 12, 20: PRINT USING &quot;Belt length =###.### inches&quot;; bl
LOCATE 15, 25: PRINT &quot;Continue Y/N = Y&quot;;
DO: k$ = INKEY$: LOOP UNTIL LEN(k$)
IF UCASE$(k$) = &quot;N&quot; THEN COLOR 7, 0: CLS : SYSTEM ELSE GOTO start



Nick you might be able to use this source code at your site
you can use it to compute belt length between pulleys. Larry Meaux (meauxracing@mindspring.com)
Meaux Racing Heads
MaxRace Software
ET_Analyst for DragRacers

http://www.mindspring.com/~meauxracing/

 

[NickB]

Thanks guys, i've been teaching myself to TIG weld over the past while. The stock injector angle is even steeper than i have them now, something around 75-80 degrees. I have them set now at 45 degrees, and the pintles are much closer to th airstream as well. (I'm not impresed by the factory manifold at all) The injectors i'm using don't have very long noses so i can't lay them down any further or they'll start to pull to far out of the runner.

I had to grind the first set of injector bosses off after i welded one of them on. I made them ou of 7/8&quot; stock and put the hole in the center. The only problem was that this mad them thin, and on welding the upstream edge, here was nothing that could be done to keep them from melting because of the tigh angle in there and the proximity to the o-ring groove where they're REALLY thin. Those ones are made of 1&quot; round wih the holes offcenter, so there's a lot more metal at the backside to weld to.

Larry, i see you did some investigating on my website, hehe. That program would work very well, except that i can't think of a single application i make a pulley fo that has a belt going around only two pulley. They're all combinations with at least three pulleys on the belt. When i calculate the belt length i just take the stock belt size and subtract the difference of the circumference of the pullys affected multiplied by how far the belt wraps around each one of them respectively. I've made a few sets for custom applications sight unseen an the size i recommended always worked out. (I have yet to see a set of the Saturn pulleys installed, and i've been making them for almost 2 years, and sold around 100 sets)

 

[GeoRacer]

Hey guys I wonder if you all could help me out with my intake project. The motor is a 1855cc DOHC 4 valve Isuzu engine in a drag only car. It's putting out around 430 turbocharged hp right now.

Here is my rough design, 9 1/2&quot; long velocity stacks going to a 3 1/2&quot; square plenum 17&quot; long. The stacks will go though the floor of the plenum and rise above it about 1/2&quot;.

I'm planing on installing th einjectors at a 40 degree angle to the runners about half way up the runner, the port NOS will go just above the fuel injectors.

I'm looking for a power peak around 8000 rpm with a usable power band of 6000 to 8500 rpm.

Goals for this engine are at least 600 wheel hp, to help
acheve that goal I have a port NOS system installed jetted to 100 hp and a small &quot;dry&quot; jet (around 30 hp) just after the turbo and before the air/ water intercooler to help more with air temps then anything.

Am I on the right track?