sup all. Both times the car was put on the same dyno and both times the number are SAE. When the motor was fresh 2 years ago , it put down 240whp and 150tq. Leakdown test was done and compression was 260psi all across. Now 2 years later , i just wanted to check and see how the motor is doing. It is still putting down the same leakdown and compression numbers. The AFR remains the same and nothing was changed on the motor. At the dyno, everything remained the same but once it got to 8000 rpms , it didnt climb anymore and torque began to drop instead of staying leveled. i ended up with 233 whp and 148tq. I am NOT unhappy or anything. just curious so i decided to post. What contributes to power loss when a motor wears ? it seemed to have performed the same as when brand new but ran out of breath out of nowhere at 8000 rpm since and torque began to drop 1000 rpms sooner ( redline is at 9200 ). maintence was done both times ( new ignition , oil , etc. )

 

#1 is you can't compare dyno numbers like that. try trap speeds.

how many miles? if it is a lot as a daily driver an injection cleaning might benefit. a real injector cleaning.

also... 240/150 ? isn't 150 tq a bit low for 240whp? i would have expected 160-165.

 

hmm ... u can't compare SAE #s on the same dyno at the same shop ? ... I would think trap speed is worse to compare since it's on different days but before , it trapped 112 and now it's usually 109-110 . it is a daily driver with 30k driven these past 2 years. again, I'm not complaining about the power output and power definately goes down through wear. I was jus curious how it climbs up the same way throughout the powerband and stops climbing at the last 1000 rpms where the old one keeps climbing. it be nice to restore it to it's tiptop shape. it seems like most likely it's not an internal problem because for 8,000 rpms , the power and torque level are identical. then somehow, something it tires out for the last 1,000 rpms so it might be an easy fix.

so far , my guesses are maybe a dirty throttle body , dirty injectors , or maybe cam gear settings since cam lobes are wearing ? I dunno ... any suggestions ?

 

If you go out of your way to replicate the test then you can minimize the number of variables in the test to the state of maintenance on the dyno and the mileage on the engine.

If the oil is the same weight, the valve lash is the same, the suspension settings are the same, the tires are the same, the tire pressure is the same, the cam gears never moved and the belt didn't stretch, your fuel is the same, your injectors are clean, the fuel filter is clean, your spark plu gaps and distributor/wires are all in the same condition, your compression test is approximately the same, the tension on the tie-down straps is the same, etc.

With my daily driven engine running big cams I get a lot of carbon/goo buildup on the intake valves from stop and go traffic and a polluted intake charge so I know for a fact that my valves are not permitting my head to flow as well as they once did after 55,000 street miles.

I still get pretty good torque and 30mpg so it's hard to complain much.

-P

 

Tune up?

 

Reading owns me at times.

 

thanks for the responses ... oil and oil weight is the same , spark plug gap is the same , tire and tire pressure is the same ... good point on the timing belt stretch ... can that be corrected by moving the cam gears ? the motor probably have buildup also but I guess there's no easy to clean it huh lol ?

 

Temps?

 

Temps should be corrected for by the SAE setting. If the wheel alignment is off, it can drop power output on a dynojet about that much. A dynapack obviously wouldn't be affected in the same way.

 

wow really ? .. which part of the wheel alignment would be most important ? .. toe , camber , or caster ? .. i guess what i m asking is , would a camber kit really help or adjusting toe would solve most of it ?

 

Toe or Camber being out will cause a power loss of roughly 3% or more on a dynojet (depending on the severity). If the car is strapped down more tightly than last time, it can have the same effect because of the increased amount of friction. Correcting these things and making them as close to stock settings as possible will help power reading on the dyno, as would strap tension.

 

will that 3% loss of power happen throughout the entire rpm range , or jus uptop ? like mentioned before , the power and torque is identical to each other when i overlay it , max torque hits at around 7300 rpms. In the old sheet , it carrys on all the way to 9,000 rpms but now , it drops almost immediately after reaching max torque. because of this , the HP tables instead of climbing up.

 

sounds like something changed in the timing map or cam timing a little bit. Are you running a cat convertor?

 

What's your setup?

 

no .. i m running a 2.5inch straight pipe. i ll have the local tuner play with the cam timing again a bit. About the timing map ... can touching the distributor change that ? .. because i took out the distributor out to change the igniter and coil but i made sure i marked it and i realigned it the best i could.

 

Also depending on your head's state of repair the valve seats could have been worn down (from bad guides), affecting maximum flow that would have power drop off and have less of an effect on the low end.

 

Yes, but if you went through that much effort to make sure you reinstalled in back in the same position, it's tough to say. You'll need to see where the base timing is vs what your tuning software says.

 

Of course you lost BHP numbers. You have carbon build up on the back of the valves and in the EX. port. This is like engines 101, it hurts your air flow.If your rings are fine, do a head/ valve cleaning and valve job and if you nave no cam/rocker wear you will make more than before. This assumes your bores, crank and bearing are still good, your friction will be less, and improve your numbers with a head work.

 

Yes, it is. Continue with the lecture.

 

Sure, do you think 2 years of carbon build up on the valves and in the ports would?
A- increase flow
B- stay the same
C- decrease flow
I know this is hard to understand.
would a catalytic converter after after 2 years of running rich and has a carbon build up?
A- increase EX flow
B- stay the same
C- decrease EX flow
Engines 101 does air flow make any differance?
A- NO, I got big cams
B-No, I got big compression
C- Yes, it is an air pump.

 

Ahh, may I haz a C.

 

haha .. thanks for the lecture. i realize that engine wear , etc causes power loss. i jus thought that it be everywhere , not just at top end. i guess there's nothing i can do about it until i rebuild it. Does any chemical actually work ? .. i've had a smog guy told me to use Sea Foam to clean up the insides for better emission. Can it work here ? any other things that i should try out ?