I


Modified by NICEHATCH at 6:32 PM 7/20/2008

 

Needing backpressure: myth. What you do need is the correct vacuum. If your exhaust is too big, you lose power.

the best example I have ever heard was this. Think of it like you're syphoning gasoline...if you've ever done that. If the tube is too big, you won't get the pull that you need.

 

Also, don't dynojets correct for temperature and humidity?

 

for the best results for that header you need a built head and bump up the compression

 

<TABLE WIDTH="90%" CELLSPACING=0 CELLPADDING=0 ALIGN=CENTER><TR><TD>Quote, originally posted by 1GPlusSH &raquo;</TD></TR><TR><TD CLASS="quote">Also, don't dynojets correct for temperature and humidity?</TD></TR></TABLE>

They have an SAE correction option, this guy didn't use it.....

OP: use the SAE correction, and you will get more steady numbers, your STD numbers are going to be a bit high, they're usually a good 5-10hp too high, change the correction to SAE and it will be the same.....

 

STD numbers are also corrected, just to a different standard than SAE. Comparing the "Actual" HP/TQ numbers from one session to another could show a difference due to temperature.

What all components were changed? Was it the same dyno? Dropping tire pressure 5psi could cost you 5whp. Was the ECU re-tuned for the new header? What was the A/F for each setup?

 

If you changed anything else between the dynos then it could change your output. keep in mind 5whp is only 2% difference, that's not much.

There's a lot of factors to account for: Induction system heat soak, fuel temperature, more drag on the brakes, new tires versus worn tires, tire pressure, various suspension settings like toe, the tension on the chassis tie downs, the temperature/humidity (even with a correction factor), oil viscosity, clean/dirty air filter, differences in valve lash, temperature/condition of the transmission fluid, wear and tear on the ignition system if there's been significant mileage between the dynos. That is why some people prefer engine dynos. It takes a lot of the variables out of the equation.

IME dropping my 2.25" exhaust (to open header) gave me more 5ftlbs more midrange on my H22, and there are all motor K-series guys running 3" exhausts, so I think that bigger is better as long as it is a smooth transition from the collector.

Larger tubing diameters on the header will typically shift the powerband up in rpms but if the cams fall out of their efficiency range before the header dimensions see their benefits then you will get no more power. Has AN-R marketed that header for "stock" motors or is it geared towards a more aggressive build?

Pirate

 

well, its a stepped header. I dont know how ANR gears their headers, but Randy only makes stepped headers for h22's making 230whp+.

 

their was like a 20-30 degree difference in the temps between the first dyno run and the second one. (the first being cooler)
even with that he is making more power after the peak drops off.
it just doesn't peak as high as before but in other parts of the graph he is making more power also

 

T


Modified by NICEHATCH at 6:32 PM 7/20/2008

 

go to the track and find out.

 

W


Modified by NICEHATCH at 6:32 PM 7/20/2008