Where did all the power go?

[dapiper]

It all started with a cam regrind from Schneider, the Racer Brown SS56/54 turbo grind.  They took 2 months.  When reinstalling, had to turn up idle screw 2 turns and only got 10" Hg vac at idle.  Used to get 12-13".  On the Dynojet 248H t got 325RWHP at 18 psi boost.  Used to be 410.  Ran cam straight up as before.  Degreed cam to be sure.  Just checked Intake open event which matched cam card.  Tried adv cam 6 deg, but just reduced top end range.

 

HP curve flattens out  at 5k to 6K RPM and does not even equal peak torque.  Motor leak down is 2-4%.  Tried another milder RB regrind from Schneider the SS54/52 which always had about the same top end power before and exceeded the hipo cam power to 350 RWHP.  The idle vacuum was 12 inHg, much smoother.

 

I've missed the whole Summer with this regrind issue.  I did send the original RB cam, which Schneider refused to regrind because they claimed the metalurgy was compromised.  It had 0.030" pitting on the #6 cyl lobe nose.  I just got it back from Delta.  Will install and compare.

 

Extensive datalogging history substantiates the big disparity of over 80 HP.  For example the fuel flow and AFR figures show the regrind cam motor is pumping less air.  Inj duty is high 60% vs high 70%.

 

Did change to Z32 tranny and CV joints in rear axles, but this can't equate to overall loss.

 

Meanwhile, thoughts and experiences anyone?+

Edited October 22, 2014 by dapiper

[Tony D]

In my testing actual CV's in the rear gave me 2-3% more HP on the chassis Dyno compared to Cardan-Type four-post U-Joints, so I doubt that hurt unless you installed them dry or packed with sand!

[madkaw]

Couldn't be an ignition issue? 

Did all other events match cam card-especially intake close?

[dapiper]

Using Autronics aftermkt ECU with DIS ign LS1 coils.  Timing and fuel map same as b4.  Tried tuning (33 pulls) to no avail.

 

Unless you mean the LS1 igniters.  Using 4ms dwell and 27 deg total at 6K RPM with dip to 25 deg at peak torque, 4600 RPM.

 

Did not check all other cam timing events, since did not install the degree wheel.  Did not want to remove rad and all the other to get to the crank nose.  Using timing marks on harmonic bal.  I can verify other events now, since adding complete degree label to balancer.  Will advise.

Edited October 22, 2014 by dapiper

[madkaw]

Did you verify damper was dead nuts TDC? I understand the PITA to mount wheel but using the crank pulley is probably not accurate .

Do you have a build thread?

[dapiper]

Yeah, all that.  I been doing this for 35 years.  Understood about accuracy, but verified within a degree or so or enough that it's not way off. 

 

Just checked blow off valve, looks ok.  Getting ready to change cam AGAIN to Delta regrind before I pull the motor 

[madkaw]

Found an old thread of yours-- sounds like I can't give you any advice:)

Good luck and hope it's not a sucky Schneider cam since they are regrinding mine now.

[dapiper]

Thanks for chiming in.  Appreciate your suggestions.  Misery loves company.

 

Tried Schneider 270 but too much cam for me, low vac and soft below 3K RPM.  260 similar to RB SS56/54, but didn't try that one.  You should be OK for non turbo.

 

Keep me posted.

[dapiper]

Just replaced Schneider regrind with Delta cam one and wow, what a difference.  More mid range torque, smoother idle, more idle vacuum 14 "Hg, grabs revs better, just more enjoyable to drive.  Was out all afternoon taking the long way home.

 

Was running lean in mid range 16:1 which shows pumping 10 % more air.

 

Spent a lot of time and effort fighting this problem.  Wish I had some recourse.  It's a jungle out there and things are not quite what they used to be, so take care, beware.

 

Will get dyno sheet soon, but AFR and inj duty confirm increased power.

[madkaw]

I hope I have better luck with Schneider than you did.

Congrats