Why would the S/R heads/XE262 Cam/AFPR make only a 1/10th improvement on the 1/4 mile ET vs standard stuff with headers?

 

traction

 

tuning or traction as ed said

 

Kiwi,

If I'm reading your question correctly, you are comparing the World heads, Comp cam, and AFPR without headers to the stock heads, fixed FPR, and stock cam gring WITH headers, correct? Not addressing the exhaust with all the other modifications still leaves one big restriction in the system.

She can only suck so many golf ***** through a 13mm garden hose. Increasing the hose to 17mm will make it just that much easier, no matter who is supplying the initial air flow. Maybe not the greatest analogy, but...

Basically, an improved exhaust will allow the stock components to work (flow) better, even though they might not be optimal. Even though low-RPM torque might not change much, trap speeds should be better with the free exhaust. Better heads and cam lobes might try to move more air, but still face that final restriction of an undersized "hose".

An improved exhaust with the World heads and better cam would be even that much better, and at that point there should be a significant improvement in performance. The AFPR may not make any difference at all - it's only a means to tune for WOT power, and only if necessary. Sometimes, it isn't necessary, and therefore is no improvement or performance addition.

 

I will second traction but its mostlikely tuning. Try messing with the timing (initial and total). Also make sure you have the RIGHT spark plugs in there. That was my problem with those heads on one of my motors.

 

thanx for replies.

With just Headers and free exhaust 14.55
With the above and heas/cam/afpr 14.4

True I haven't done any tuning yet and plan on going to the dyno this weekend.

I will have the car outta the shop today with Nitrous added and a B&M console Mega ****fter added.

I just found it strange that head/cam etc would only give me 1/10th ET, though it did give me 3 mph faster trap speed.

 

Was any port work done on the heads?

The way World leaves the valve bowls and guides borders on criminal. When cleaned up, though, the improvement is substantial.

Also, stock TPI runners are going to limit anything else you do as much as stock exhaust will. The cam will want to go higher than those long runners will allow.