Thoughts on Engine Combo and Dyno Slip

[wildjyoung]

Hello All,

I had considerable help from this forum on my build, so thank you for all of your advice and contributions. It is now complete and been on the dyno. I know the dyno is only 1 data point but I must say I was disappointed with the results. Below is my build and the dyno slip is attached. What are your thoughts with the numbers? Are they in line with expectations? What can I do to increase the HP and torque? Would 1.7 roller rockers do anything?

Thanks again for your help!

360 CI
Flat decked
Flat Top Pistons
Eagle Crank
10.5:1 static compression
8.25:1 dynamic compression
Quench of .041
Lingenfelter 74216 Cam (213/219 .493/.502 HR112)
Harland Sharp 1.6 Roller Rockers
AFR 180 heads
Lingenfelter runners and intake
Ported plenum
52mm throttle body
Hooker ceramic headers
Magnaflow 3" exhaust
EGR and smog removed
Custom tune by PCM4LESS
TCI street fighter transmission
2,600 stall

 

[grumpyvette]

no the power curve is NOT what ID expect and a brief look at the dyno info indicates a good bit of info
the cam you've selected is designed for max mid rpm torque not peak hp, and it matches the intakes designed power curve, your car should be very responsive and a good street combo.
all the parts you used look good, your making about 400 flywheel hp,but the power band should be a bit higher, Im wondering if the cams installed to far advanced ,or the intakes restricting flow, (ID INSTALL THAT CAM AT SPLIT OVERLAP, not DOT-TO-DOT, which is advanced) as the power curve falls off at only about 4500rpm, and it should pull a bit higher,the power curve falling off that soon usually indicates a restriction, in the intake air flow rates,or a restrictive exhaust,but I need more info..it may be the cam durations too limited to allow the engine to breath to its full potential.
look at your fuel air ratio. its supposed to be in the 14.0-14.7:1 range at idle and swiftly get richer as the rpms increase to about 12.6-13.0:1 at about 3000-6000rpm/ wide open throttle if max power the goal, your F/A ratio, if I'm reading the line correctly (ITS NOT THAT CLEAR) the f/a ratio goes serious lean or seriously rich, as rpms increase indicating either (if its going lean) a serious lack of fuel pressure,or injector pulse duration,if the injector pulse duration or the injectors are just to small, its a problem (or if its going rich) its a serious lack of injector pulse duration control) the ignition timing advance curve is also suspect as the power curve seems to fall off too early, which is mostly likely from the lean mix but may indicate the timing is not advancing far enough

what other info can you provide, clear pictures of the spark plugs and knowing your exact ignition timing and intake vacuum readings and exhaust back pressure would sure help locate the potential problem...
btw whats your rear gear ratio?
hows the car feel while you drive it?


this thread may help

viewtopic.php?f=55&t=8485&p=29767&hilit=volumetric#p29767

viewtopic.php?f=50&t=9250&p=33361#p33361

viewtopic.php?f=52&t=5078

 

[bob]

http://airflowresearch.com/articles/article115/A-P1.htm

you might find this interesting

 

[wildjyoung]

Thank you very much for the quick response and helpful information!

I will take some pictures of the plugs and post them later this week.

Fuel pressure was set at 42 psi and base timing was set at 10 degrees. The injectors are 32 lbs.

The tuner made a comment that he had to pull back fuel because it was starting out too rich at idle, so you are correct that it started to go lean. The tuner was most familiar with LS based combos and admitted that he has not worked on TPI in a VERY long time, so I am not sure if that made a difference or not.

The cam was installed dot to dot.

The rear gear is a 3.23. The car feels good but something does seem slightly amiss. Like your comments, it just feels like there is a restriction up top. However, I do feel it is important to note that the transmission was shifting early but the tuner said it was a non issue since he does not turn on the dyno until the car hits 3,000 RPM.

The tuner did comment that the engine will not be completely dialed in until I get a heated O2 sensor. He said since I have headers and no catalytic converter the O2 sensor readings would be very inaccurate.

Is there a printout I can post that would provide more insight into the timing curve? I have TTS Datamaster and the cable.

Thanks Again in Advance for Your Help!

 

[wildjyoung]

I am finally responding to a very old post. Shortly after I started this thread I got married, started a new job, and purchased a new house. However, I am back to fine tuning my car.

I found something very interesting that may explain the dyno results in the original post. The tension screw that holds the intake tube to the throttle body was blocking the action of the throttle body. Therefore, when the accelerator was to the floor it was only actually at around 65% and obviously not nearly at wide open throttle. Would this explain why the air fuel ratio was so out of whack?

Either way, I am going to head back to the dyno in a few weeks and see what I can register with a car that actually goes to WOT.

Thanks again and I am happy to be back to the forum!

Josh

 

[wildjyoung]

Here is the newest dyno run! What are your thoughts? I really wanted 350 RWHP. Should I switch to the TPiS Miniram and just install the NOS wet kit I already own. This is just a fun street car that may occasionally go to the track. I want it to be streetable and fun.

 

[grumpyvette]

both dynos show the power peaks rather early in the rpm band, this is usually an indication of a restriction to intake or exhaust flow rates, the heads are not the restriction, the headers and exhaust need to be tested but should be ok, that 213/219 Lingenfelter duration cam seems to be the restriction, I wish your dyno showed a good deal more info like the effective fuel air ratio, the lines on the bottom of the graph look like your in the ball park but your obviously a bit too lean at lower rpms and a bit too rich in the upper rpm range, an exact ratio at each rpm, vacuum readings,at each rpm step ,and ignition advance curve etc, would be useful

but the one factor that seems rather obvious is either the intake or exhaust flow is restricted , Id suspect its the cam in this case that needs to have more duration , but with out vacuum readings in the intake plenum and exhaust back pressure readings plus knowing the fuel air ratio and ignition advance its difficult to point out the flaws in the combo
personally Id suspect its either a restrictive exhaust or a cam swap too one with a longer duration would help.
why not call at least three cam manufacturers, other than Lingenfelter but also call them,and get their suggestions, Id suspect they all may suggest some cam in the 227-236 intake duration range here
but it would be very helpful to know your exhaust back pressure and plenum vacuum readings at every 500 rpm point, and your ignition advance curve,because it would be very helpful in isolating the problem
looking over the parts list and results Im thinking the cams installed too far advanced or the cams to small in duration to allow the engine to breath.
your 2600 stall and 3.23:1 rear gear ratio restrict your choices here but Id sure discuss options with a minimum of 4-6 different cam company's, plus linginfelter and get those plenum and back pressure readings.
I had a engine build about 20 years ago that had similar symptoms and as soon as the exhaust was tested it was found to have 6 psi of back pressure at peak rpms that totally strangled the power.


NOTICE THE EXPECTED POWER BAND IN THIS CHART VS YOUR CAMS DURATION, and how in theory adding 15 degrees more duration would change the results

viewtopic.php?f=52&t=1070

 

[wildjyoung]

Thank you VERY much for the assistance!

We did one run without the cold air intake and it added 10 RWHP! The tuner said that it the log it appeared that something was being restrictive which he thought was the entire intake. The exhaust is a Magnaflow system without any catalytic converters. 2.5 inch into one muffler with dual 3" outlets.

I will see if the tuner can send me some of the readings he took while doing the dyno run.

Again, thank you! I will call some cam manufacturers and get their thoughts on a good cam for the combo.

 

[grumpyvette]

Ive had , or had friends use and have very good results with these cams, in similar engines but obviously you can,t select a cam without doing the math required
CROWER 00471
CRANE 119661
CRANE 119651
lunati-20120712
lunati-20120713