building my own efi intake

[80broncoman]

When I worked at crane years ago (1991) they started to build one for a EFI 302 (late model stang).
It never got finished. I was bugging the R&Ds guys every week about it.
I wish I could have talked them into finishing it.

 

[6bangerbill]

broncoman,
This is a little off suject, but when you worked at Crane did they use faster lobe valve opening aceleration rates with larger tappet diameters? It seems that with some cam manufacturers you do get better cam action and lift with flat(large diameter) tappet cam lobes than with roller lifter lobes at lower duration, like under 270 degrees. With Comp Cams they equalize at about 285 or 290 degrees with a .906 dia lifter. This applies only to hydraulc lifter type lobes. If true, why use a roller on the street? The only answer Ive found, so far, is the dificulty of breaking in the cam at start up in the case of the flat tappet cam. What are your thoughts on the subject?

 

[80broncoman]

but when you worked at Crane did they use faster lobe valve opening aceleration rates with larger tappet diameters?

Yes, But only in less than 5% of the catalog parts. You get wat you pay for, But this is not to say that the .842 Dia profiles are cheating us ford guys. When I was there I noticed that the other major cam companys did the same. Its all to make more money. less tooling changes on the machines means more $$ per cam.
But I look at it this way: My 300 ford runs the 260-H cam(.842 Dia profile)
$99.00 from jegs A special grind would have been $187.00 What would I have gotten for the extra 87% of money? Maybe 3-6 more horspower.
Big deal I am sure I made up for it. I have about $87 in my new valves
Which gave me as much as the cam.
The Newest profiles when I worked there were of course Winston Cup
.875 dia profiles. TLF profiles (Tight Lash Profiles .010-.012)
The rule was back then no lifter over .875 dia.
(I have seen Restictor plate cams at 242 Duration @ .050) To turn a max of 6800 Rpm. (This was in 1991)

If true, why use a roller on the street? The only answer Ive found, so far, is the dificulty of breaking in the cam at start up in the case of the flat tappet cam. What are your thoughts on the subject?

GM spent some real money in the late 70s on Round lobe cams. And so did many of its customers, Including me.
The factories use them maybe so they can put 5w-30 Syn oil in the cars
To get better milage.
The General public thinks a roller cam HAS to be better.
I can tell you more about this but I have to go to work now.

 

[6bangerbill]

I had Comp Cams custom grind a 285/297adv dur,241/247 deg at .050,.618 lift on 108 centerlines cam with chrysler lobes for $200.00. I bought a set of new mopar hyd lifters,ls1 comp cams behive springs, used titanium valves, and titanium retainers on ebay.I felt the high lift cam was needed for the high lift valve flow of my cnc ported fs1 head. Flow steadily increases well past .600 lift.All of the off the shelf cams listed only lifted to the .400 to .500 range. I just could not waste the heads potential that way and hydraulic roller cams (if I could afford it) didnt match this particular lift figure anyway. My engine analyzer program told me I needed this kind of duration to get to my 7000+ rpm target .

Do you have any knowledge of the proceedure required for enlarging lifter bores from .875 to .904 dia?Some reading has suggested a .003 over sized bore diameter, using a fixture mounted in the camshaft bore for reamer alignment. Is this a common proceedure, maybe followed by a light honing to a final dimension? Any suggestions would be appreciated.

 

[80broncoman]

I Can completly understand why you bought a custom ground cam. No cam company is going to have anything close to that in a catalog.

As far as opening up the lifter bores, I'd just measure how much clearence there is with the ford lifters installed and copy that.
One note of caution look close at the oiling band on the side of the lifter
and make sure the lifter get oil at ALL times and that the band does not get exposed (above the block)due to the high lobe lift.

 

[lyonsy]

hey
sorry havent been on for a while so just catching up.
yeah ive been reading about the 3 pulse system about 3/4 weeks ago in exhaust.
and also how scavanging works basicly a big lacker ban in the air molucules thats strectched when the valve close's and when tuned right the valve opens when the molcule comes back forcing the others along and increasing the volmetric unfortently this only happens in 3 parts of the rev range when lucky most times once.
also been playing with desktop dyno with some cam profiles and trying to get a some that does 300hp/300ftlb so far got the torque 301ftlb but only cracking about 220hp on the stock head.
and kills everything else for torque buy about 80 ftlb
oh working the length again as well its 19.8 to utalise the first wave 9.9 to use the second and 6.6 for the third wave for 5000rpm.
jsut a quick thought on vairable runner length etc .
most of it is to keep the air speed up?
if so why not mount 6 throttle bodies up on a manifold after the plenium have an electric motor hooked in to open them up a set rpm say 3500rpm and have them half closed at below 3500rpm.
this will keep the airspeed up when in low revs and restrict the airflow very little if you use a 5mm (1/4in) larger throttle boddie then the manifold.
yes theres more
how whould you setup a tunnel ram manifold on a 6cly cause i think its kinda what i thought of with the seperate front + rear cyl ide with plenium.
oh and i thought the fs1 head wasent going crossflow due to the dizzy or has it been made so it can be inseroius hp application.
ill have more but ill post it later.
drift

 

[6bangerbill]

Hey,
Trying to find manifold design information is a real chore. Try to find "Intake pulse Tuning by David Vizard" on the WWW. This article will either inform you or glaze your eyes over.I read it over and over to get his concepts. He discussed the plenum really well; with suggested volumes and the split plenum concept for the six. And gives some formulas which are dubiusly helpful.

The data given by my Engine Analyzer Program gave the following recommendations for my 300 six for a 6400 rpm max torque:

Inertial tuning: 12.5 "long, 3.77 sq in.
2nd pulse tuning:21.6" long, 6.52 sq in.
3rd pulse tuning:15.5" long,4.69 sq in.
my choice : 11" long, 3.33 sq in.
Note the suggested runner lengthes are all over the chart!

My 11 " long runners give max torque at 5800 rpm and horse power increasing well passed 7500 rpm. Volumetric Efficiency of 115% at 6350 rpm. Can't explain why, but 11" seemed to work best (theoreticly)with a lite weight vehicle.(and fits under my hood).I also cheated by measuring an aftermarket chevy single plane intake.( a "team g" Wiand runner measured between 10 and 12 Inches long) For comparison, a stock ls6 efi chevy comes with 15.6" long, runners and makes good power up to about 6000 rpm.

Please notice that the area measurements listed above are an average over the entire runner. The smallest port cross section area should be located and enlarged to keep port velocity below 400 ft/sec. My smallest area is 2.825 sq in at the pushrod location and the maximum is near 4.0 sq in. at the plenum for an average of 3.33 sq in.A velocity of 400 ft/ sec is reached at about 7,400 rpm.

The fs1 aluminum head I built is actually two ls6 corvette chevy heads cut and tig welded to form a single cross flow 300 ford head. The runners, after cnc porting, flow over 300 cfm at 28 inches with 2.04" intakes.Torque of 400 ft lb should not be a problem with this kind of flow, starting at 4000 rpm and higher. Horse power is only limited by how much rpm you are brave enough to pull. Note, these are only theoretic calculations not dyno figures. I still have allot of fabrication of parts remaining .

The 6 throttle body idea would increase velocity only in a small area next to the throttle butterflies thus causing a slow, fast, slow mixture speed. In my mind is a picture of an "incredible shrinking runner" that shrinks in area and grows in length at low engine speeds. This ideal runner will maintain the same runner air velocity and the desired tuned length at all speeds with no comprimise. Good luck with that.

By the way where did you find your exhaust tuning length calculation information?

 

[lyonsy]

hey
i found the info here but no calulations unfortenly http://www.sportbikes.com/wwwthreads/sh ... ain/767872
oh ive only got desktop dyno where can i download a copy from?
drift

 

[6bangerbill]

drift,
Thanks for the exhaust link, go to autoware .com for engine anylyzer software. See engine only software. I bought the dos version many years ago its still only about $109.oo. You dont get formulas, but feed in your data to get hp curve feedback. Mine is old with flat tappet cams only.

 

[MustangSix]

Why not a variable length intake runner such as is done on many newer cars? It would be entirely possible to do with a PWM output. Mechanically, it could be either a "trombone" or an additional runner length that is activated via a throttle type blade by the ECU.

concievably, you could even control it via a load or rpm sensing device, not unlike opening the rear two barrels on a 4bbl carb, therefore not needing a computer.

 

[6bangerbill]

It takes a more patient fabricator and machinest than I am to build a dual runner manifold. It will feel really good to finish the single runner item Im working on. Any way, the missing lower rpm torque should not be missed; Im using a 4r70w transmission's lower gears and a little higher stall converter.Just keeping it simple. Overdrive with a 4.56 rear axle will keep cruising rpm at about 3000. My shorter runner manifold works from 3k rpm - up.

 

[80broncoman]

I just thought of another way to make a active intake. Make two plenums for two carbs with a large balence tube connecting the two plenums. (like the old 2x4bbl ciffy intake on a 300)
In the middle of the balence tube install a throttle body.
Just keep it closed till about 3K rpm.

I am actully thinking about this idea on my new jeep intake.
Look at the intake:
http://cgi.ebay.com/ebaymotors/ws/eBayI ... %3AIT&rd=1

 

[6bangerbill]

Good idea!The following is the results of three plenum conditions on a 314 cfm port flow fs1 cross flow head, a single 750 cfm carb on a 300 ci inliner engine with a 285 deg cam, .618" lift. Total plenum volume is 300 ci, runner volume is 665 cc, and runner length is 13". Two carb barrels on each plenum. These numbers are from an Engine-Pro modeling program.

100% open plenum- 535hp @6800, Torque-477 ft-lb @ 5550
100 % divided- 504 hp @6800, Torque-452 ft-lb @ 5450
Small slot between plenums- 513 hp @6900, Torque-459 ft-lb @5500

Two four barrel 750 carbs increases hp to 545 @6950 and torque to 485 @ 5600 rpm. Dual carbs required the small slot for max performance, the open plenum reduced hp to 475 hp! Trial and error rules the day. Note too that a 665 cc intake runner is about 30% more area than the stock efi manifold runners provide.

 

[Anonymous]

Vizard's intake runner formula, where
L: length
V: speed of sound in f/s
ECD: effective cam duration (use nominal - 30 degrees)
RV: reflective value
D: pipe ID

L = (((720-ECD) * .5V) / (RPM * RV )) - .5D

 

[6bangerbill]

It might be helpful to note that according to Vizard in a recent article, the tuned runner pulse length is much less important than the effect of inertial tuning. THis may sound erreverent to the tuned length crowd, most after market single plane manifolds have really short runners due to space limits, but perform really well. The problem is that inertial tuning information is not published that I can find. My Engine Analyzer program does give out a 12.5" long runner @ 3.33 sq in (inertial tuned length)for a 300 I six at 6400 rpm . It also gives 2nd and 3rd pulse tuning dimensions if you prefer them. The pulse lengths were 21.6" and 15.5"(too long for my lower hood height).

 

[6bangerbill]

Found the formula for inertial tuning, its the old long ram chrysler stuff similar to your above discussion. My application came out to 12.74" for the sixth wave at 6400 Rpm. Haven't found the volume formulas yet.

The old Chrysler formula includes your intake cam duration in it's formula, and it uses the sixth inertial wave bounce. The original Chrysler calculation was for 2800 rpm and required a 181.5" long runner! Divided by 6 (for sixth wave bounce) gives a 30.2" runner length. Intake duration was 268 degrees. Doesnt sound like a "racing" manifold,at 2800 rpm. These were mostly automatic transmission super stock automatic drag cars. I guess high stall converters were not available in the early days.

Give me your intake duration and I'll give it a whirl.