Did some testing with different intakes, motown single plane and HSR….
All tests are on street with a gtech Pro SS and I have dataloggs of all runs that shows the same results so far.
Idle start, no spinning ( low stall 2800rpm, 2.48 1’gear and sticky tires ) and open loop tune all the time.
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Motown Single plane intake, ported with custom made elbow to fit under firebird hood
Cruise AFR is within 0,5 between LH/RH and BPW is 0.9 to keep it happy at 1800rpm and afr around 15
WOT pull AFR 12.5 bpw around 4.0msec

60feet 0-60mph 330feet 1/8mile 1/8-mph 1000feet 1/4-time 1/4-mph shiftrpm
2.10 4.30 5.514 8.26 91.58 10.623 12.59 115.0 6000

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Switched to HSR ported ( better flow nbrs than SP )
Cruise AFR is within 1,0 between LH/RH and bpw is 1.2 to keep it happy at 1800rpm and afr around 13.0
WOT pull ( with exactly the same tune as SP)

60feet 0-60mph 330feet 1/8mile 1/8- mph 1000feet 1/4-time 1/4-mph shiftrpm
2.08 4.42 5.531 8.35 89.11 10.777 12.81 112.0 6000

WOT AFR went up to 14………
Tranny start slipping 1-2 shifts, rebuild it and it now shifts smoother/slower so the sprags doesn’t go bad again…..

Increased the fuel and lowered the timing 2 degrees, WOT bpw around 4.4

60feet 0-60mph 330feet 1/8mile 1/8-mph 1000feet 1/4-time 1/4-mph shiftrpm
2.02 4.08 5.369 8.08 93.13 10.389 12.32 118.0 6000


Increased the fuel some more and did a test run, but the tires spun whole first gear so didnt get any performance data worth comparing…Worse grip or more torque??
And it was still lean in some spots but cant get it to hook anymore. I think it getting to cold to hook on the streets.

But so far the HSR flows more and has better performance than SP but the SP has better and smoother cruise conditions ( due to better low rpm air distribution ) and I can get better milage with it…
Will add some boost later…..and then maybe the results will be different……….
Also I don’t know how much the rebuildt tranny affects the times…..

I have tuned a few HSR setups and it seems like when the cam is getting around 230 intake it needs to go rich below 2000rpm to get it to run smooth.
Also its clear that hsr is suffering from split BLM on my setup.

Will see what next step is, boost with HSR och try the SP intake again……….. But this will have to wait until spring 2017…..

 

Interesting test. I wonder how the motown single plane compares to a eddy victor efi single plane? Or how a ported sp would have done?

 

I dont know how much pressure the guy is using on his bench since the nbrs seems overall high compared to other nbr on the web.


But the HSR flowed 385cfm ported ( will see if I can find the nbrs before porting) and here are the nbrs for the motown ported 1206 vs flowmatched
1. 336/346
3. 317/346
5. 325/348
7. 337/350
2. 343/346
4. 328/346
6. 300/330
8. 330/344

 

385 seems really optimistic from a 1206 port but i guess what matters is the test was done on same bench at same time

What heads are on the motor?

 

correct, same bench.

AFR 210 Eliminators

 

Both manifolds seem to flow enough to not pose a restriction to the head but i guess only way to tell is to flow both together.

Cool comparison tho, i always liked hsr but seen single planes go faster, and work better for distribution

 

Yeah I know what the numbers says. I made this test to be really sure what my split BLM and hesitations below 2krpm running stoich really was the intakes fault.

Next year I will take it to a dyno and se what the nbr says.

But It really flows less in my setup with SP, since it needs more BPW to get same AFR...

 

Was the single plane flowed with the elbow?

A buddy of mine at MIT about 10 years ago did some software modeling for me showing various radius elbows and runner lengths. It really had an interesting impact on airflow. I was trying to understand why a SP I built (efi conversion) with an adapter plate and a 75MM throttle body with a big hat made more power than an off the shelf holley with an elbow and larger throttle body. It's all in the radius and how it disrupts the air flow.

A singleplane with a 4bbl throttle body will flow the most, but you need a large enough 'hat' or you run into the same problems, which of course causes hood clearance issues.

Can't win.


-- Joe

 

No without elbow, and since the firebird hood is so low the elbow is far from the best and it probably make a diffrent.

Since the SP is off the car now I will se if I can get it flowed with the elbow just to compare.....

/N.

 

Yup i got a 4" cowl hood to allow for a bigger taller radius elbow on my car and i have been happy with how the plugs look

 

I've been looking at some of the newer multi-injector throttle bodies lately. I wonder if for a blow through application they would work well.

-- Joe

 

I might be able to add some facts for you - I will replace my Edelbrock Vicor E EFI with a Motown but probably no result until spring -17.

 

That extreme air cleaner lid style could also solve the issue as long as the hood isn't immediately above.

 

I don't have a comparison to SP but been running HSR for about 7 years or so and I have never been able to get the front 4 and rear 4 plugs reading the same. But this is mostly cruise DD use. I have gone to lengths to get air to the rear including PCV routing and currently have basically an 3/8 hose air leak going to the rear of the plenum with the TB almost closed and IAC counts in the single digits. It does run and idle MUCH better but the rear plugs are always a little darker. I think part of it is the PCV too. Any oil that gets in is blasted to the rear. That's my theory anyway. I have wanted to go to a single plane but like the looks and layout of the HSR so well it doesn't seem worth the change. Power is good though.

 

Did some more tuning with the HSR

Same procedure as last year with "Idle" start

60feet 2,06
0-60mph 3,88
330feet 5,329
1/8mile 7,94
1/8-mph 97mph

Thinking of testing without the 3" intake pipe since I only get 90kPA at WOT now..... But not to happy with driving without airfilter..


Otherwise I'm happy with the times so I guess it time to boost it

 

You will never get the front 4 spark plugs to read the same as the 4 back plugs because the Holley Stealth ram has always had a fuel reversion problem.The fuel is pulled up into the back of the intake.

 

Could be, whats the cause of this? and why dont the SP have the same problem?

 

Because it has a common plenum in the center, with nearly even distribution to the cylinders.

Singleplanes can have similar issued when the elbow is not designed properly (assuming an elbow is used). I had a thread on this back in 2007/2008 when a buddy of mine from MIT did some airflow modeling for me.

-- Joe

 

As I see it the HSR also has a common plenum

The biggest diffrence (as I see it) is the location av the TB, on a single plane its more it the "middle" of the plenum........

But if we are thinking of fuel reversion it shouldnt matter or?

 

Front mount throttle intakes are prone to have the issue depending on design. In the hsr, the front 4 runners are right at the tb opening. 2 things can happen. Air can get taken first by front 4 and leave little for the back 4, or if air velocity is high in a boosted application or some small diameter intake tube, air can skip over the front 4 and hit the rear.

If i recall on my build, i believe i saw richer rear cylinders most of the time during part throttle. Back 4 plugs and pistons looked to have more fuel which is less air. Front 4 were getting the air from tb at low velocity part throttle.

Idk about wot i never looked at per cylinder wbO2 or checked plugs

 

Yeah, GM recognized this effect with the LT1 and added idle air bleed holes to help feed the cylinders equally at idle.

Which I ended copying to solve the problem on the Miniram... (except I ditched that ugly intake muffler you see in the photos and made the hose a little longer, which had the same effect of quieting it down).

https://www.thirdgen.org/forums/diy-...ram-split.html

 

Lt1 also has injector offsets in the code to even out fuel distribution

 

94 and later, yeah...with the sequential injection

 

So is there a fix for the air/fueling distribution on HSR? Could the top be cut and angled up so the front sits higher than the rear? Similar to the holley hi-ram in shape. Or is it more complex than that?

 

It's probably fairly complex with all the pressure waves and what not going on inside the plenum. Cam selection may play into it as well since it tends to govern the manifold pressure at closed-throttle idle speeds and that itself could play around with air distribution.

I tried various things to cure the idle split BLM issue before I came up with that small idle manifold idea... We don't have the luxury of trimming fuel on a per-cylinder basis with these TPI's, so the only thing we can work with is the air distribution.

For instance, I got a long tube and hooked it up to the IAC hole in the back of throttle body. Trimmed the tube to various lengths. Intuitively the idea was to have the IAC air be distributed from somewhere in the middle of the plenum such that every cylinder had equal chance to get the air it needs. I also tried a perforated tube. But it didn't work. Also tried a tube that took a 90° turn out of the IAC exit and went up toward the roof of the plenum. That didn't work either.

The only thing that worked as that idle manifold.

I guess you'd have to just experiment with stuff to see what would work. But if you're not having driveability symptoms, I'm not sure I'd waste the effort. With me, I can definitely tell a difference in idle quality with and without the idle manifold.

 

Plenum shape would help. Ported intake to make all runners equal in flow could help.

 

In 94+

92-93 didn't, which had fuel distribution issues.


Also people can't compare batch fire with sequential. On batch fire $8d, $59, etc the injector is typically spraying on a closed valve. All sorts of things can happen inside the intake manifold, including pulling fuel out of one runner and moving it around in the plenum.

I'm sure some of you have pulled an intake that was only briefly run and noticed the tan fuel stains all over the place.

-- Joe

 

Why not just run open loop?

Even on my '94 Vette, closed loop has screwed me. I have a o2 sensor on the right side that reads wrong. Enough to cause about a 10 point BLM swing on that bank, which causes it to idle around 1100 rpm from commanded 675.

On my Firebird I disabled o2 correction after getting the tune dialed in. last thing I need is the wideband to crap out and leave me on the side of the road. Miniram car.

-- Joe

 

I run open loop, have done for 10? years cant get the car to run good in closed loop. The car runs OK now as long as I runs it a tad rich on lower rpms, with the singleplane I could lean it out some.

Batch fire I'm sure making the problem worse, and the cam tends to be a part of the problem. I have tuned a few HSR cars with smaller cams and they dont have this issue in low rpms.

I'm thinking of building a new plenum this winter just to test, one that is lower in the back like most of the sheetmetal intakes plenum to see if it helps.

Anyhow I'm going to switch to seq. this winter with 8egt and individual cyl trimming and so on, so I guess It would be easier to tune this issue away. I've had code$59 since 2007... burned my first eeprom 2000, made the 730ecm swap 2003...sure going to miss it and tunerpro................

 

I acutally do run open loop at idle now (since about a month or so ago when I found out SAUJP gave the option). Not so much for idle quality (it was really good in closed loop too), but the off-idle transition is much sharper with open loop idle using the Miniram.

 

As a question to those out there running alternative EFI systems, I have a MS-II. Would it be worthwhile to consider running the "banks" front to back and then using split table to lean up the rear cylinders some?

 

Clever.. give it a try and let us know how it worked out.

You can have 4 injector drivers on your ms2 so you could
Trim it too.

-- Joe