Questions: Back from shop, ported heads with dyno sheet

[postalbunny]

Just got her back from the shop today... originally in for low compression, leaking exhaust valve (72% leak). Found this just after purchase trying to check a/f. Had the heads ported while they were getting a valve job. Got a few questions regarding the dyno graph:

My torque seems to start out at 500 and drop, is this because the heads are ported and i'm not pushing enough air... possibly need to twin screw or put a 4lb lower on. Or is the port job poor? I wasn't able to get a boost reading from them, so i don't know if boost is dropping off.

Also, the a/f seems to be right inbetween 11.5-12. Should I have this retuned to be lower? I also asked, and they said the stock MAF wasn't getting pegged... seems like everyone else with a similar setup is running a BAP+MAF. Also, most stageV ports seem to be at least 500rwhp.

I do realize it's not that far off, and 94 deg F with 40% humidity may not get everything she's got.

setup:
steggy stage V ported blower
accufab single blade
jlt rai (carbon fiber)
LFP h/e + LFP resevoir
2.76 upper + 2lb lower + 4 idler setup from LFP
bassani mid-length + off-road X
mac cat-back
tr6ix gapped at .32
Also got head cooling mod while engine was out.

Also, upon purchase the seller stated it was SCT tuned and made 475/457. I have no sheet to support, but this is my basis for wondering why the torque is dropping so much at the upper end. I also don't know if the seller had it tuned with the bad exhaust valve or not.


Any feedback appreciated.

 

[postalbunny]

Bump... anyone?

 

[Nutty 5.0]

I believe the torque drop off you see is what almost all of us eaton guys have: top end they lose efficiency. Some others here can chime and give better reasoning, but mine has done the same pre port and post port especially when pushing double the stock boost output; think its to be expected.

Not sure if you posted a dyno sheet since I'm at work but I read 11.5-.7 on a/f with the sensor place in the rear O2 sensor bung and 12.0 on the tailpipe sniffers. My tuner says I should not worry and he's one of the top in the country; where was your a/f sampled at?

 

[postalbunny]

Good question on the A/F, i'll have to call up and ask. The reason i was worried about the torque drop is that most people with Stage V's have a flat torque curve that raises a little in the mid rpm range.

I searched and haven't found anyone with a torque curve that drops the whole run. I'm not sure if I got extra torque with the ported heads at low RPM and the rest of the curve is ok (not likely, thought the opposite was supposed to happen) or of something in my combo is causing me to start losing torque around 3500rpm.

If it's the eaton that's causing the drop-off i'd have no problem purchasing a twin screw later on when money permits, but if the torque line was still flat after spending $3-4k more i'd have to commit suicide.

 

[x NOODLES x]

Give or take my eyes being off here's how you and I compare. (Also Stage 5/2.76)

TQ.

RPM You Me
35 495 480
40 480 487
50 465 480
60 465 440


All in all seems close. Add the ported heads, 2lb. lower and less than ideal conditions..........

Any ice down runs????? Also my numbers are SAE.

 

[x NOODLES x]

Why is the HP so low would be my question???

 

[postalbunny]

HP being a product of RPM andtorque, I figure if I fix upper rpm torque then hp will naturally Inc.

Thx for the compare.... Maye i just need to try And get a quick run in when it's cooler to get the hp I was expecting.

 

[dredg9]

what type of timing you running?