Hi all!

I finally managed to get my GTA tuned on the dyno.
As far as I can say, I think the engine runs nice and smooth, and it feels nice, too.

But the numbers give me rather bad taste.

Maybe some of you can take a look at my log and bin file if something is wrong.
I think the engine should do around 50-70 more rwhp.


Engine setup is that:

383 SBC Gen1
AFR195 #1040 Heads
Jones Roller Cam , 224/226 in/ex ; 280/286 ; 0.528 / 0.535 lift with 1.6 rocker arms
1.6 Roller Rockers (Yella Terra)
Holley Stealthram Intake
SVO Red Top 30lb/hr Injectors
Stock 48mm Throttle Body
Stock MAF Sensor (descreened)
Hooker 2055 Shorty Headers ( 1 5/8" ) ; Empty Cat ; 2 1/2" Stock Catback with Flowmaster 80s Muffler
T56 Transmission
Ostrich Emulator

Should be everything which would be important.
Programs like Dyno2003 / Dynosim 5 tell me I should have around 500 engine hp. That could be unrealistic, so I was thinking to get results in the lower 400 hp range.

Reality shows other numbers, unfortunately....


Little translation service: The upper curve is torque in Newtonmeter.
The other ones are engine hp and rwhp. Din corrected, not SAE.
Numbers are measured in 4th gear.

Before I forget: There are several "timeouts" within my log, where all values jump around. That has something to do with my Windows7x64 , when I use Virtual XP Mode, these errors don't occur.

Can someone help me solving this problem. I really think i should be at least in the 320-340rwhp range with my setup.

rgds
Alex

 

Can you post a couple of print screens of the datalog during that event?

 

Here's an excel sheet of my log.
http://dl.dropbox.com/u/23685391/Dynos/log.xls

Should be best to read the sensor values. Hope I didn't forget some data which might be necessary.
Vehicle speed is not yet available ( need sgi5 vss converter )


Alex

 

I'll trow out my observations, since it is practically impossible for me to spot anything "in flagrante" on the xls file.

Looks like 90-100 map cells are all filled in with "37" deg SA.

WOT around 5000 rpm O2 is and stays around 870 V.
If it were around 970 V it would not catch my eye.

30 lb/hr injectors @ 43.5 psi should be good for around 450fwhp.
30 lb/hr injectors @ 43.5 psi = 40 GPH and that appears to be the max fuel a new TPI pump can deliver.

Is it possible it it was lean?

 

My wideband tells me it's rich, around 12.x A/F ratio and the tuner said i'm ok with fuel delivery. He just said that the camshaft is limiting my power output. But when i see for example the engine specs of 1992 firehawk and compare... i really should have more than 350fwhp.

What do you mean with the SA table. Something suspicious?

 

Need to play with the SA (spark advance) and VE tables and see wich way it runs best.

Should have mentioned AFR 12.X @ WOT @ around 5000rpm (wich is not necessarly rich) in first place, NBO2 is tricky.

 

I thought that your combo would have had better results too... and why doesn't you HP and TQ cross each other @ 5350 RPM's?
My combo made 330Rwhp and 349ft/Lbs on a lean tune... (15:1 WOT)
Now what's the problem?...Hmmm
You have enough Cubic Inches...
AFR Heads don't need lots of spark advance... 37 may be too much...
Heads Intake and Cam flow well enough...?
48mm Throttle Body may be restrictive...
2.5" Catback Exhaust might be restrictive as well...

 

Numbers don't cross because it's newtonmeters, not ft/Lbs in torque.
As far as I know, the 48mm Throttle Body flows at around 650cfm, which wouldn't be a restriction. The Holley Stealthram isn't a restriction either.
Catback would be interesting, but somehow I doubt thats the key to sucess.

I have some spark tables from other ppl here on tgo with similar engines, some of them with significantly lower spark tables. I'll try out some of them, maybe I see some gains in tq/hp or losses.

I spoke with my engine builder before, he said that the hp curve looks ok, but the torque is too low....
Here a comparison between an engine he built for another customer ( same engine, but carbed and not yet set up properly )


As you can see, the rwhp's are more or less the same, while the torque curve differs dramatically.

 

Good luck!
I'm interested in the outcome...
I have much the same combo ready to go in my car.
383 11:1 HSR 218/224 with 180 AFR's

I hope you find the answer.

 

Agree!!! Need much better exhaust system. Minimum 3" 'Y' pipe, cat, and catback.

 

Probably unrelated but you might have a shorting coolant temperature sensor/wire. Looks like your INT dips way down when the coolant temp goes negative 40. I'm a speed density but it might be effecting your load variable too?? dont know what that is... also your SA goes to the thousands of degrees at those points too.
EDIT: My bad. I just read about the timeouts......

 

I could try if I gain something with open headers/ypipe, but buying a new 3.5" catback system or building one myself is not yet an option.

The ypipe + cat is 3" , rest is stock 89' 350 catback (except the flowmaster muffler).
I have a 52mm throttlebody in stock, which didn't fit properly ( my stealthram is milled down to fit under the hood without cutting , problem: throttle linkage will hit my fuel rail fitting, at least if I use the 89-92 style throttle cable, so i used an older one with the smaller throttle linkage)

Later today I'll first try some other spark advance tables to see if there are any gains in the midrange I could make.

One thing I've seen on http://www.pypesexhaust.com/faq.html:

And here's another one:
http://www.hobracing.com/tech/tpi_flow.asp

Really strange... there are calculators out there which tell me I'm good with ~650cfm flow , on this side the flow is good enough for 300hp. I think I'll really try if I can swap in my 52mm throttlebody. Hope I get it fitting... If I only could swap over the linkage....

 

If you have engine in car and you could drive it,go to autobahn and do some wot passes.Measure exhaust backpressure and vacuum at plenum.If plenum doesn't go near outside air pressure(zero vacuum)->air filter,maf or tb is resictive,and if backpressure isn't near zero(~less than 3kPa)then your exhaust is too resictive.

 

With good flowing heads like the AFRs, I'm not sure I understand why the cam specs? Your exhaust is bigger than the intake. What's the overlap? Are you trying to make up for the exhaust system? What about compression ratio?

 

wow that is kind of puzzling. i have a similar setup, only my largest flaw is my cast iron 882 heads, and still made more power than that. maby slightly less hp, but wayyyy more tq. one thing that imidiatly jumped out at me was that stock tb.

 

WOT pulls, only require to play/test with the 90-100 kpa SA cells. Once happy can then smooth in the lower map cells.
Also play/test with the 90-100 kpa VE tables, if you suspect rich, lower the values and test it.

What does the MAP kpa show during the pull?

 

@Thomas: I don't have VE tables or kpa readings in my 6E binary.
I'm not familiar with the speed density systems.

The VE tables equivalent should be the maf table / or power enrichment vs rpm / or power enrichment vs lv8 i think.

Looks like I really have to try out my 52mm throttle body.... hope theres any possibility to make that "new" throttle linkage working (without touching my fuel rails). I think it's not an easy task to disassemble a tb?


In fact you are making more HP. Your signature says 312rwhp, and that with an automatic. I just have 290hp to the wheels with a T56.

 

yeah that puzzles the heck out of me. because i was aiming to get those same exact heads and a little more cam before i am satisfied with mine. but are you doing the tuning and renting a dyno? or do you have a tuner doing it?

 

I have a tuner for that work. Paid alot of money for the work which was done by now ( round ~$1100 for around 4 hours of work.... yes, germany is expensive) and as far as I see, it's not worth it yet. Engine is still stalling sometimes when I brake down and press the clutch pedal, and its shaking the whole car when i drive in 1st-3rd gear with minimal throttle... seems to be something spark+fuel related, maybe too lean...
Anyway, I don't think my SA Table was that perfect that only the WOT range from 4000rpm on had to be edited. Just about 20 out of ~200 cells in the sa table were edited, and that just up to 2° differrence. Rest of the work was some fueling stuff & closed loop calibration.

 

Peter,

In a Speed Density motor, you'll see the VE drop after the torque peak but it shouldn't drop very much. If it does at WOT, it indicates a restriction in the intake tract. I mention this because you are thinking about the larger TB.
I don't know what the MAF equivalent would be, but it would be the telltale
of not enough available air.
In the 60's you'd calculate the size of the carb CFM needed for a particular motor and a 350 would calc out to ~600+. However, I would run a 780 Holley resulting in more power. I use a 63mm TB on my 5.7L LT-5 with no problem. However, the power peak on the LT-5 is at 67-6800rpm.

 

My bad, at some point missed it was MAF.
Fueling and SA probably remains the main key. As to what values and cells to tune, in this case, is out of my knowledge.

 

There's another Dynosheet from my Android phone.
That was before there was any tuning done on the dyno.
HP+TQ curve match almost exactly the first run on the dyno.

As you can see, the HP curve flattens at ~4500rpm

Looks almost like people say about the disadvantages of a regular TPI induction system. great for low to midrange rpms but weak in the upper range.
When I see that curve, I think more and more there must be some restrictions in the intake passage.
In a few days we know more. My little Android-Dyno will show some results when my 2x52mm Throttlebody got in
I really hope this does the trick, but somehow I just think, if it's not the TB anymore, it'll be the MAF, Air Filter or the intake ducting itself....

 

While not a perfect comparison, this article illustrates losses (and potential for gains) in the Firebird MAF intake ducting. Note that the car in question is initally running aftermarket speed density through the MAF and standard ducting.

http://www.gmhightechperformance.com...ipe/index.html

Similar gains should also be had by simply converting to a 4" intake duct and MAF.

You could always duplicate this 4" tube and integrate a slot style MAF directly into the tube, or use an existing 4" MAF housing as offered by Blowerworks.net. Just use couplers and bends to make up your own tube. Special tuning required to suit the new hardware, of course.

Heck, Greg might even make up the complete tube for you.

Bottom line: It is not necessary to convert to SD to take advantage of increased flow capability of a larger MAF and related duct work.

 

On the LT-5 we have a similar problem w the snorkel you see on the front of the airhorn in the pic I have attached. At WOT, it collapses. At idle, even a stock LT-5 will suck the vinyl cover off a three ring binder when you attempt to perform the vacuum leak test by blocking the air inlet. Again, not certain if this is totally analogous to what may be happening to Peter, but his motor is definitely looking for more air than stock.
On the black "airbridge", I use an aftermarket phenolic insert to stiffen up the snorkel and keep it from constricting airflow. We've seen differences of 10-20rwhp because of this.

 

Another thought: I could convert to speed density and get rid off the maf/ducting and simply use some tubing and a proper air filter unit. Getting a 730 ECM and some other stuff shouldn't be a huge problem, even here in Germany.
There are lot's of 3.1L V6 around which are parted out. I won't need a memcal anyway as I use the ostrich emulator.

 

Here is a thread where the intake ducting was collapsing with the loss of power. SD TPI set up:

https://www.thirdgen.org/forums/diy-...-dropping.html

RBob.

 

What he said, those headers, cat back and muffler are killing you.

Those headers are covering part of the large AFR exhaust port.

 

for that small of a cam.
T Body
and headers

it's not so bad.
if you want make power. ya got to get bigger parts. guys have been doing it for years

sorta like running stock ex manifolds on a 454. then sticking on a 650cfm Holly.
(not going to work so well)

383 SBC Gen1
AFR195 #1040 Heads (good start)
Jones Roller Cam , 224/226 in/ex ; 280/286 ; 0.528 / 0.535 lift with 1.6 rocker arms(better then stock)
1.6 Roller Rockers (Yella Terra)
Holley Stealthram Intake
SVO Red Top 30lb/hr Injectors
Stock 48mm Throttle Body (Go bigger)
Stock MAF Sensor (descreened)
Hooker 2055 Shorty Headers ( 1 5/8" )(go bigger) ; Empty Cat ; 2 1/2" Stock Catback with Flowmaster 80s Muffler
T56 Transmission
Ostrich Emulator

look at lingefelters, look at what they did to there 50 state smog 383
good place to start.

 

I really don't see why my camshaft should be such a limiting factor.
Especially when I see the camspecs of the lingenfelter cams. Those advertised for L98-LT1-LT4 look less radical and these engines surely produce way more power.

Btw any suggestions for good headers which fit in the engine bay, hopefully without removing anything from the AC etc.?

 

Peter,

If you are referring to my comment, I was asking because the AFR heads you've selected flow very well and are efficient in terms of the ratio of intake to exhaust volume ~ 75%. Too much exhaust with too much overlap may cause the intake charge to flow out the exhaust port. Also, there's the issue of the valve staying open too long robbing compression. In my 84 stock block Xfire, I used TFS 23d heads 64cc chamber/195cfm ports, a single pattern 219@.050 roller cam w a .528"lift w 1.6:1 roller rockers. Not far off from your cam. So for your 383, the cam may be a bit smallish IMO on the intake side. I was using
1.75" TPIS long tubes for exhaust. I agree the shorty headers gotta go.

 

Thanks for the explanation - With your help I think I'll get the proper environment for that engine. Swapping the camshaft is not really an option. IMO the idle is rough enough (I still have to pass smog tests and technical checks, could be a problem if the engine looks+sounds much different than a stock engine ( or at least what people think it should look+sound like *g* )


Today I swapped to my 2x52mm throttle body and did a little test drive. It feels a bit healthier, especially in the midrange. Next will be the Maf sensor. I'll fabricate a larger housing for the sensor and recalibrate it.
By any chance: Has anyone did that before? I think I should tweak the maf scalars afterwards, right?
One more thing: After I swapped in the 52mm TB, i had no more stalling when I pressed the clutch and no more bogging in 1st/2nd gear on low speeds without any load.

 

I'm not well versed with TPI, but that camshaft is SMALL.. particularly for a 383 stroker. You should be in the mid 23x/23x at least if you want more power.

Most of the higher output motors I've seen have cams in the mid/late 230's to mid 240's duration to allow a stroker to breathe more, thus making more available power.

Even then, I agree that the exhaust is probably a contributing factor as well.

 

I think I'll do some upgrades on the Intake as soon as possible, and then just drive this season. Next year probably complete exhaust and maybe another camshaft, looks like everyone recommends a larger cam.

Today I found out, that my MAF sensor had some problems telling the ecm whats going on.
The moment I plugged in my spare maf the engine ran alot better in almost all rpm ranges and load situations. ( Just not the upper rpms 5000+ , stock maf with screens.. engine runs out of air i think )

 

Peter,

Interesting article on Holley SR using a 355. Here at GM HiTech
http://www.gmhightechperformance.com...roc/index.html

 

Whenever you do, contact Steve @ Lunati. He's really good friends with Harold (designed a major amount of shelf grinds on the market for most domestic applications), and knows his grinds well. He helped me in my cam selection and I couldn't be happier. He's a no BS kind of guy and loves to talk about different builds - not just sell stuff. Great guy, honestly.

 

For some reason I can't see the dyno charts.

But if as you say, you are only getting 290rwhp, that is very disappointing. I am at 290rwhp/380ftlb with less head, less cubes, less intake, less cam.

I think upgrading your exhaust should be your first project. That seems to be a major bottleneck. Or first you could try another dyno pull running the exhaust straight out the y-pipe. That would at least let you know how much the 2.5" piping is costing you.

 

Cam is fine for much more power than you have now. Although on the mild side it should still make more power.

You need to go bigger on the exhaust. 3" minimum. headers could be better too. Collectors are so small on those. 1 5/8" ports dont cover the heads well and could be a minor flow restriction.

Stealth ram flows enough, intake is not a problem Check to make sure your MAF is working right.

 

That's worth a try


Looks like I'm planning the next steps
Intake + Exhaust. Another cam swap won't do the trick before I upgrade those I think.


I've been playing with "Engine Analyzer Pro" ( which was featured in Dominic's link about the Stealthram 355 Engine ).
I see the most gains in power with upgrading my intake ( I used all the values I got from my engine, and guessed the intake+exhaust flow, intake based on the cfms of a stock bosch maf sensor with screens -> 550cfm ; exhaust was somewhere around 300cfm, really don't know what to use there... )
It got pretty close to my actual dyno results.

This is the one based on my actual setup:


This one assuming I have twice the exhaust flow than before


This one just with a heavily upgraded intake from air filter to throttle body


And finally this one which is full intake+exhaust.



Do you think I could make comparable gains with those upgrades?
I still don't believe in those programs ^^

 

I dont think intake/tb upgrade is gonna gain THAT much power. The pontiac intakes maybe abit more restrictive than the camaro TPI intakes but the MAF is capable of over 400whp.

 

I did some research in what the tuner did with my starting bin file.
Maybe someone can take a look on it. In the next 1-2 weeks my GTA will be back on the Dyno to correct some problems. ( Cold start is way too rich, cruising airfuelratio is too rich (around 12.0-12.6, at least thats whats my wbo2 gauge is telling me, could explain the horrible mileage.... gets around 13-14mpg on the autobahn at 75-80mph in 6th gear (which is around 1600-1700rpm ; under normal driving conditions with regular traffic, 50% city driving i won't get much more than 10mpg.... )

http://dl.dropbox.com/u/23685391/Dyn...Comparison.pdf

Does anything what happened to my bin file makes sense?
For example, I don't see why my injector flow rate has been changed to 22. ( I have SVO Red Tops, which are 30lb/hr )
On the other side, there are so big changes in my Maf scalars and Maf tables. Shouldn't be there smooth transitions between the Maf tables?
Another thing: It looks like the tune has been done while the ECM was in closed loop mode. Would that be a no-go? Heard something like that from a friend.

 

I've been using Engine Analyzer Pro for many years now and can tell you that once you get it dialed in and properly matching the real world engine it will point you in the right direction for your changes.
I've had it match real world changes on a 427 big block to within a couple of HP. The ability to chain multiple tests to zero in on the best combo is priceless.

Anyhow, about your engine. I'd for sure be looking at intake airflow, TB, MAF and ducting. It looks a little small to me. And those shorty headers arent doing you many favors either. Besides the diameter problems, the primaries are way too short. Since you have EApro go ahead and run some comparisons with different length's and diameters.

From your above post it is very obvious you are way out of tune, dont let that guy tune it again.

 

yeah doesnt sound like he knows what he is doing. Change injector constant to the correct value and tune from there. Should not need much MAF table adjustment and only alittle PE vs RPM enrichment adjustments to dial in WOT fueling. Get it fixed and work the cruise tune to 14's to 1 or so before you hurt the motor from being too rich

 

I would not remove stock screens because of what I have read that the MAF can read air wrongly. Plus the stock MAF with screens flows more than enough for a NA 383.

Your intake should flow very well up top.. It's odd that it flatlines at 4500RPMS. My 310ci (ported&polished heads, cam, forged bottom end, etc.) with AS&M runners, ported plenum, accel manifold, stock injectors, 48mm stock TB makes 216RWHP and around 280RWTQ (HP peaks at 4800RPM and TQ peaks at 3000RPM). I tuned PE WOT % enrichment so that when i go WOT my O2 sensor is around 900mv which is just about right.

 

Im starting to wonder myself if this guy knows what hes doing also. The spark table looks weird to me. Alot of initial timing also. My smaller motor with a larger cam runs less timing at idle. And Im starting to think I have too much.

 

Got my car back from the dynoshop.
It's running better now, still not that power output but I think I'll see some gains as soon as I throw in some longtubes and a new exhaust system. I'm still not sure if I'll use a true dual exhaust or a proper sized single exhaust. I haven't had the time to look at the changes in the bin file, but it's running leaner than before, starting is better as well, and there is no stalling when the clutch pedal is pressed.
So I think we are now going in the right direction. Anyway I think there is still plenty of room left for further improvements. In order to do that, I'll take my bin and merge it to the apypwb.bin, and do some datalogging with wbo2 data directly in the aldl stream. Could help to tweak some of the maf tables.

Anyone reading this thread can suggest some good headers for me? I heard longtubes can interfere with the slave cylinder of my transmission?

 

I've heard Dyno Don's headers are a good performance header and have great fitment. I know there system can run with dual 2.5" cats and then back into a single 3.5" exhaust.. That's what my plan was when I drop in the 383.

 

In the meantime, I got it run properly... and wasted alot of money to let this work be done.

If I only read Orr's tips for tuning before

With my current bin (apypwb merged with the bin I paid for) I just needed around 3-4 datalogs to get the fueling in the right direction.
The main problem was another one, which the tuner really had to find out, but he didn't.
It was my fault as well. I really don't know why, but my Initial Timing was set to 11° in the bin, and it was at 0° mechanically, so when I fixed that, the idle got alot smoother. I don't have to tell you that throttle response, power, torque, and even my fuel economy got a lot better

Still no engine knock at wot, so I think I could advance a little bit more.
Most of the time it runs now by 14.7:1 ( +/- 0.3 ) , light throttle is somewhere in the 15.2-15.5afr range.
I still have no SGI-5 converter, as soon I get it, I think I can work a little bit with accelleration enrichment , dfco and highway mode.

In the next days I try to get a timeslip and dyno run done with my phone, but I think we're now around 380hp and a little bit more torque.

Next step:
Subframe Connectors (already ready to be welded in)
Headers (I think I'll get the DynoDons)
Catback (probably the borla system, I like the plate system... could be a little bit more neighbor-friendly when I use the closed plate *g* )

Here is the latest log I was running:
https://dl.dropbox.com/u/23685391/Dy...kv2maf2bin.xls

 

Looks like I made some improvements. It still looks like I'm limited in the upper rpms. Will be exhaust I think. I'm not sure about the torque numbers ( should peak at around 4000rpm ).
570nm = 420 lb/ft

Temperature was about 10°C hotter than the run on the chassisdyno which resulted in 340hp/510nm tq.

 

Good job!!!
And Congratulations!!!

Now go have some fun!!!

 

100% agreed! Your exhaust is a huge choke on your setup without even looking at your programming. You seem to have a nice shortblock put together but the rest is garbage. Your gonna have to step up on larger headers, better y-pipe and at minimum a 3" mandrel bent exhaust with a much better muffler. Might consider the Hooker LT's and the Hooker Aerochamber catback! Trust me... I've been down this road with my 355! For starters get a catback on at minimum! You'll need to retune after a major exhaust redo though so keep that in mind.