hotrod03

Well first, here’s what I had done to my heads.
After only 6000 miles on my 427 vert I started hearing sounds of valve train noise I didn’t like. One guide out of spec and three others almost out of spec.
Stage 4 head work
Ported polished
New exhaust valves (Feara)
Moldstar guides
Milled .020
PSI 1511 springs (may have number transposed) lol
TI retainers
160* stat
Stock engine

Before the work it ran good! A little slow getting to 7 grand but I was shifting at 6500 anyways bc from 6500 to 7000 seemed slow and needless. When and if I did a cam change i new it then would run strong to 7 grand.
Moving on to the completion of the heads and for the test drive. I knew my butt dyno would indicate an increase in power, but it was really
More than I expected!!! My butt dyno reported a good 40hp maybe more!!
Power gain was across the board, my low and more high!! Got some warm
Weather so I could get some traction on this lonely road where I could test second gear roll. What happened next really surprised me!! Rolling into the throttle passed 5 grand, I expected the same slow rpm rate from 6-7 grand, and I really wanted to see what would happen when I hit 6500 bc the engine just seemed like it reallly wanted to rev. Motor hit 6 grand and BOOM hit 7 grand, and it could of gone more! I had traction as well!! Holy
crap a major freight train pull! I couldn’t believe it!! Which mod made the difference, I don’t know, probably all of it combined. Halltech should arrive next week, then DYNO!! Khole! Well done!

jimbob8915

Any tuning?

hotrod03

Waiting to get my Halltech, should be next week when it arrives, then I’m going to schedule dyno. I will post when I get dyno. Thanks for the reply!

MTPZ06

I’d be careful on winding the car out until you get a tune...especially with the bump in compression (mill). Detonation can ruin your motor.

hotrod03

OMG! That’s right!! Will do thank you! Going to drive it easy......... doesn’t the computer have a knock sensor and retard it if it did?

rpmextra

yes but it retards the timing AFTER a knock is detected.

MikeOC

MTPZ06

Exactly...and under load (WOT), often times it’s too late.

TXGS507

Man... I dropped my car off last week with a new tuner... While he and I were driving he told me to get on it a little... I did and he noticed some detonation... HE actually "Data Logs" with his tune and takes his time. He doesn't simply throw it on a Dyno and call it a day.... I would not be rev ing the engine up w/o a tune...

Jaybird29

I just got my car tuned using AHP heads (ported with .020" mill). AFR was lean (11.9) around 4200-4900 rpms.

Bryan91SE

I had my heads done later last year by AHP and also had a mill. I was not recommended a tune. What would be recommended as a first mod to accompany a tune if I so chose?

nuke61

Long tube headers.

Jaybird29

CAI would be best mod. Headers will not help that much unless you change cam. The LS7 exhaust manifolds flow pretty well. Adding headers does not give the 40hp on LS7 like they did on an old school SBC.

I had port work done, so it flows more air. Just milling you are probably OK. I would contact AHP and check with them.

slammin86

11.9 on a na ls7 isn't lean...!

American Heritage

hotrod03: Thank you for the great feedback!
We often get reports back from customer how our ported heads picked up 15-35rwhp so your butt dyno might be pretty close to accurate.

Regarding tuning... Tuning is always a good thing as it optimizes things even in a 100% stock condition. With that said our ported heads typically do not require tuning to run safely and pickup power however tuning will help optimize the new more efficient cylinder heads.

https://www.americanheritageperformance.com/

Bryan91SE

Kohle, is it your opinion that the milled heads of .030, would need a tune given the increased compression?

427V8BB

yes, just happen to me recently and its costing me a pretty penny.

hotrod03

Tell us the story?

Landru

TXGS507

yeeesss do tell