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

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.

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.

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

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.

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

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...

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

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.

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.

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.

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.

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.

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.

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.

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

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

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.

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

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.

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.

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.

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..

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

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.

Didnt BadSS run an out of the box First?

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.

One of the guys here is putting together a 383 w/AFR's and a "First" complete system.

It will be very interesting around here in the next few months.

I will be installing a combo like Allen's in my car soon, but with a T-56.

I think that I will come in on this one. Taking about the MAF sensor. Madmax is right, anythimg above a mild motor having a MAF will require a good tuning effort. Some MAF flow numbers:
stock MAF with screens 518CFM
Stock MAF w/o screens 658 CFM ---> good for about 506 Hp (flywheel) I would almost kill for a 506 Hp engine.
docs home made MAF estimated to flow 900 CFM, this is the electronic guts of a factory MAF cemented into a 3.5" OD aluminum tube.

I had to go with this MAF to feed my 395 cu.in. stroker.

Also, I did alot of tuning. To get the right MAF flow, I had to change the scalars for the 6 MAF tables. I used 1F, 40, 6F, B4, FF, FF,,, and yes I hit the numerical limt of 255 gms/sec in table 5! Far before that happens though, I have gone into PE mode, therefore I add the extra fuel via the fuel-RPM table. So even when the actual air flow exceeds 255, I can still get the correct WOT fueling. I am kinda proud of this home made 900 CFM MAF.

Any pics of the home made 900cfm MAF sensor? What rwhp did you TPI set up net with the said CI? Sorry, just saw your sig.

The 340 RWHp was with minimal tuning. I think that it may pull 355 now, but that is just a guess. My MEGA MAF can be seen in reply #10 and the matching large airlid is in reply #23.

http://www.thirdgen.org/techboard/tp...stand-maf.html (Help me understand MAF upgrades; what stops us from using LT1 MAFs??)

In our quest we may have found the secret.

The motor is in...testing this weekend.

I think there are going to be some dismayed 4th gen owners this comming Monday.

With all the gremlins that showed up after the install, we ran out of time to do the dyno tune, so we just made a few educated guesses and ran it it.

Not bad but there is still more left.
Didn't make an all out run but it produced a new set of numbers,
12.63 @ 108.69

Good going Don. Nice times. I agree this motor needs to get on the dyno to get it fully tuned and then see where it makes its power. Then Don will know the shift points.

One more thing our third gens were running better times than most of the 4th gen cars out there.

Any updates? I'm really looking to build a 350-400bhp motor for my '88 IROC someday. It'd be nice to have a good recipe to go by. It looks like the tuning will be as important as the mechanical work. I need to lean more about the MAF and the language of the programing GM used. I was really hoping to see some higher hp #'s. I seem to currently have plenty of torque as I can burn through 1st and 1/2 into 2nd gear with 230k on the original 5.7/700R4 powertrain. I know a slick will help cure that, but I want some more top end power. Thanks, Daniel U

"I'm really looking to build a 350-400bhp motor "

All the motors above are with rwhp numbers. They will easily meet and surpass you goals.

I changed the values up 15% and it is still hugging the lower values except at just off idle then it hits the higher limits ????

Thats what I did several years ago but I'm in a 4" tube. I had the car running with it but I have never had the time to finish it.
Soon I shall be back !!

It may be that you arent flowing any more air than that. I cant say for certain, but that would be my guess if you modified the right values within the code. Try lowering them to less than what you're flowing now and see if it limits airflow to your new numbers.

Hey 88 IROC 355 made 340 hp and 420 foot pound of torque @ the wheels with a very loose torque converter and a wrong camshaft. It will run 12:50s all day long @ 111 MPH with the heavy factory rims. If you have any questions just ask.

That's right about where I want to be. Maybe with a manual trans and a better cam for that set up it would be closer to 350+ rwhp. Thanks, Daniel U

Hey man, if you want to go fast on the 1/4 the auto trans is better. A 700R4 like mine can take the power but the 1st to 2nd shift drops the RPM too much. If I ran a turbo 350 the car should have been a lot faster, but I like the over drive for the highway. You could also get a beefup 200R4, it is better for racing because the 1st to 2nd shift is closer to the turbo 350, less rpm drop.

As much as I enjoyed running my car at the drag strip, I enjoyed running at Laguna Seca more. I boiled my brakes there though, so a built 5 speed from Tremec is the way I'll be going. The most humbling experience I've ever had in my IROC is watching a 4 cylinder WRX STi walk away from me in one of the straight aways at Mazda Raceway. Hence the need for more hp. I understand that there will always be someone out there with more money or hp, but I want to build my IROC to appear factory (with some headers and exhaust) and be able to stun people with it's capability.(See my vB for all the details.) I'm sure there are cheaper ways to go about my goals, but I really enjoy my IROC, so that's the platform I'm going to use.
Back on topic:
Has anyone breached the 400bhp with a TPI on here without power adders(blower/supercharger/NOS)? I'd really like to lift my hood and say, "Look for yourself, it's an L98 with headers and exhaust." I also want to pass CA. smog. I know that wieght and wieght distibution will also play a hand in all this as well.

You might be able to pull it off with large diameter tube runners that would appear stock. Definetely with SLP style runners.

You would also need an aftermarket intake manifold. This would also appear to be stock. Any plenum mods would be internal so to speak and appear stock.

I'm running the AZ. S&M runners with a 58mm TB and port matched plenum. I know I'll need a new base intake. I'd also like to send them all away to have them extrude honed. Free flowing alum. heads will aso be added eventually with black powder coating to retain a stealth look.

Hey man, my 5.7L 1988 IROC makes more than 400 hp and 450 lbs of torque @ the crank. That is enough to pass a Subaru STI on the straight. Those STI's are not that fast on the top-end, they are just quick from a dead stop and out of the corners because they are all-wheel drive and their turbo engine makes 300 lbs of torque at low rpms. I saw the STI club in Ohio @ the track. The fastest one ran a 13.01 @ 101 mph with 1.70 60 foot times, my Turbo Integra with only 10 psi of boost ran a 13.76 @ 112 mph with 2.62 60 foot times. With 400 crank HP your IROC will no have any problem smoking a Subaru.
If you build a motor like mine with a 5 speed tranny you'll have a nice street/race car with a working A/C like mine.

I yanked my A/C when it went out. Saved me about 50lbs or so with all the lines. I want to be able to smog it here in CA and keep it legal for the street. Are you willing to share your recipe?

throughout this thread and the one that is linked in the very beginning, which talks about the modified entry angle and cross section, it was mentioned that you guys were going to flow a vortec TPI manifold.

did that ever get done and were results ever posted? curious how that compares to the stocker.....