SLP IROC-Z

its been a while for me but whats the stock computer capable of working to rpm wise?

Kevin91Z

Single Plane EFI will pass a CA sniffer but will not pass the visual, unfortunately.

The stock computer will allow fuel changes to 5400 or 5600 rpms, I forget which. If you use the "Super_AUJP" chip it allows fuel changes up to 6400 rpms.

Kevin91Z

The next test was started tonight. We removed the SuperRam and installed my old set of AS&M large tube runners. With a LT4 HOT cam and ported Corvette L98 heads it made 318 RWHP at 4900 and 419 RWTQ at 3600. First road test tonight shows it has a TON of torque down low. I didnt get it over 3500 rpms but it sure pulls hard and acts like it wants to spin the tires easily. We'll dyno on May 3rd, I believe. Then I'll remove these runners and go back to the SLP siamesed for our racing event over Memorial Day weekend.

__________________
1991 Camaro Z28
355 RWHP, 360 RWTQ
12.803 @ 108.50 MPH (1.923 60')
Member: Southern California Thirdgenners
-=ICON Motorsports=-
Work: Manley Performance Products

Orr89RocZ

awesome, cant wait to see how those runners work with that setup. Interesting to see where the peak is rpm wise, and how much it makes compared to the superram

1989GTATransAm

Thanks Kevin for the testing and the trouble you are going to in interest of science. Should be an interesting test. Glad May 3rd looks good for the dyno, maybe a phone call to confirm things or I can go by there. We have to get ready to go head to head with those nasty 4th gens.

Just for those that are interested and tests comming down the pike here are some tidbits. I'm currently working on a set of SLP runners for a member that have been modified by siamesing them down to the last 2 inches of runner. The remaining runner portion will be opened up to 1.75" id. Already at 1.70"+. This is something that anyone can do with a lot of grinding and access to welding.

Also this same member is having a set of custom long tube runners made up with a 1.775" inside diameter tube. This one should be very interesting as it is a long tube and with what should be high flow. This test will tie in very nicely with the test that Kevin is performing.

We have already opened up the Edelbrock TPI intake manifold to 1.800" to accept the above runners. So lots of things happening here over the comming months. TPI RULES!

Edit: Hopefully in June or July we will be running the exhaust collector test that has been talked about.

Orr89RocZ

NICE some good things coming. Surprised no one has tried the full FIRST TPI setup with its already very large ports and runners out the box. I'd be interested in seeing that if not already done

1989GTATransAm i know you have the first base, but with custom SLP runners

82FirebirdTA

I have pulled my stock Super Ram and Accel base off of my motor and will be modifying them. I hope to have results in a couple of months. Too bad I won't be ready for the May 3rd dyno...

1989GTATransAm

....and factory plenum. Let us not forget that Burnout91 will be doing his HSR swap so that will give us some more data.

1989GTATransAm

The dyno at Mark's will not be available on May 3. I tentivaly made a date for May 10. If this does not work we can let Mark know.

Kevin91Z

Ok, here are the results from our dyno May 10th. As expected, the TPIS/AS&M large tube runners made a huge increase in torque and lost horsepower, almost by the same amount.
They made almost 393 RWTQ at about 4000 rpms, and almost 318 RWHP at about 4700 RPMs. But again the horsepower line was flat, indicating this engine would make more power if it had more air.
So, pick your poison. Large tube runners will make more torque on the street, while siamesed runners will make more horsepower. Its about like picking between a single-plane and a dual-plane intake for a carburator. The blue line is my siamesed runners and the red line is the large tube runners.

Attached Images

newdyno.gif (59.5 KB, 91 views)

VincentZ28

Now you people out there can figure out what kind of horsepower combo you want to make and where you want to make it. High HP low torque, High torque low Hp or a happy medium.

Daniel U

So even with the large tube AZ. S&M runners, 58mm TB, and extrude honed base, I will be running out of air at higher RPM's when I go to the 383ci. Will a air ram duct to the air filter help now that my fog lamps are removed? What about the Grannetelli MAF? I've also been thinking the flex tube after the MAF could be replaced with a silicone sleeve to eliminate turbulence. I'm sure these are all ideas already out there. Just trying to maximize a factory set up.

pandin

With a Maf setup you will hit the Max air flow vs rpm table ($32, $32B, and $6E) at a very low rpm.

I have a mild 383 DD with a XR258HR10 cam (good from 1K to 5K). It rides the Max air flow table from 2000 rpm to 5000 rpm (the max rpm). This makes my 383 run like a 350. It is a grs/sec limit, air flow limit = HP/TQ limit.

To me this is worse than the 255 maf limit, cause it limits, air flow readings across the rpm range, limiting the injector pulse width, which limits torque.

I view it as a variable restrictor plate. This type of "electronic power limit" is very common in CNC spindle and table drives. You can think of it as a type of "traction control". It is used to keep from breaking parts during warranty periods.

I suspect this table is to save the OEM 700R4 from destruction in 1986.

madmax

Its a MAF diagnostic/limp home reference table, and you can change the values in the code and eliminate any issues with it limiting power if you want to.

pandin

Actually that limp table is the maf default table which is at a different location in the prom.

This is the high limit for the Maf grams/sec, if the actual maf values exceed this amount the ECM uses the lower of the two, actual vs table. So it is just a high limit as to air flow. A "Electronic" restrictor plate. RBob explains the math in one of the stickies.

Orr89RocZ

max air flow vs rpm table right?

you have to change some of those values to allow 255 gms/sec at lower rpms, else you are restricting the motor. After you peak 255 at WOT, you just add PE fuel thru PE enrichment % vs RPM

KamikazeIroccy

Nice to see this, I am currently building setup like this with the LT4Hotcam and aftermarket heads. I was going to use either theTPIS BigMouth or Edelbrock intake with Extrude-Hone Edelbrock Runners

madmax

Ok, in any case its a simple code change and its no longer an issue. Its a lot easier to work around than the 255.

KamikazeIroccy

i dont care bout all that, I just want to number,HP and TQ you guys can do the guru jumbo stuff,lol

pandin

Here is a couple of test runs at WOT.

This is a graph of the two different max air flow vs rpm tables. The only difference is the higher rpm limit valves. The 247 gr/s upper value one is OEM stock from numerous Maf chips.

The CB 255 (wells type) 205 and 187 (Bosch) are three different Maf sensors with varying degrees of age (older Maf's get smaller at the peak output). This is how I name them, by their max out put (the Bosch's are way below 255).

These are from stock 350, running okay, TPI's. The lower max output, will lean the mixture when exceeded, when used with a stock OEM memcal.

The test engine is a mild 383 with a 1K to 5K cam.

Notice how low of a rpm (off idle) that this limit table is reached and how the grs/sec follow almost exactly the limit table, till the maf sensor limit is reached.

Before changing the 6 maf tables, to richen the mixture, this table needs to be raised (as has been mentioned many times before, on this board).

Remember this data is with stock Maf's not descreened.

This puts a large restriction (electronic) on the airflow/fuel mixture of the engine (and why some mods would seem to have no effect).

To me this is the true Maf restriction and one of the reasons that SD would be preferred.

Attached Images

BUA CB vs BUA 205 vs BUC 187 Maf grsec_html_m3d3d24ef.jpg (39.9 KB, 46 views)

madmax

So change the data in the table, and there's no more 'restriction'. You cant get more HP out of a SD setup without tuning either so getting into a MAF v SD on stock proms is kind of a pointless direction to travel in and way off the original post anyway.

pandin

The point to including this in this post (Quest for a better flowing TPI), is when trying to increase the VE/airflow to the engine, the (electronic) tune/ECM can block the (hard part) gains.

If you miss changing this table, then a freer flowing intake and porting, will not give you the expected improvement.

If the 255 maf limit is hit under/before the stall speed/rpm of the car/engine then yes, this is a non/minor issue.

chrisinocala

i have a 1989 trans am gta with the 350 tpi i am going to sell it and i have let it sit for a few months.I drove it to the back of my houses months ago and i statred now and then well i went to statr it to put up for sale and now it wont start if i shoot fuel down the front of motor it will start then stall i canot hear my fuel pump humming anymore i would like to try to energize it to find out if i need to chang or not and i am not sure how to do it..

madmax

I think a proper tune is pretty much a given if you're wanting anything beyond a mild build.

Orr89RocZ

I still want to see someone do a out the box FIRST TPI setup. that i think would be killer on these cars for hp and torque since they flow more than AS&M runners and are shorter in length i do believe

Also i'm interested in seeing is a TPI setup like the ones tested in this thread and others on a motor that doesnt have to meet such strict smog laws. There very well could be a big gain in power due to more aggressive, higher overlap cam profiles and longtube headers/bigger exhaust systems that will allow good breathing up topend where these siamesed intakes seem to perform their best.

madmax

Didnt BadSS run an out of the box First?

Orr89RocZ

yeah and it did run pretty comparable to the stealth ram..actually he went a tenth faster but 1 mph less...could have been difference in weather and traction tho

But his combination was pretty mild compared to these setups...especially 1989GTATransAm's 370whp siamesed setup.