I thought that I would share my finding and see if anyone has tried the dorman and what the results were.
Dorman Products - 674-540
The above link looks like a cast version of ZZP's PLOG but $100 less expensive at ~$63 (I think that is what autozone showed them for).
I contacted Dorman about the inside diameters of the manifold they responded with this.
The manifold is cast iron
The inlet is 1.55"
The outlet is 2.029"
So lets compare the measurements of
Stock Vs. ZZP Vs. Dorman
1.53" Vs. 1.625" Vs. 1.55" Inlet
1.63" Vs. 2.25" Vs. 2.029" Outlet
(The stock and ZZP #s are from ZZ Performance )
Now for the last two important dimensions stock exhaust port and crossover inside diameters.
Exhaust = 1.53"
Crossover = 1.91"
I think that the dorman could actually be better that the PLOG in a way. How so the inlet is only slightly larger than the head exhaust port should not make a big difference. Now the outlet to the crossover is where I see it being better as the crossover in 1.91" the stock piece gets larger by 0.32" while the PLOG gets smaller by 0.34" and the Dorman gets smaller by 0.119". That with less transitions in the exhaust it should keep the gas velocity up due to less turbulance giving better performance. Plus the pipes have a more gradual curve to them and no cap at the end.
Is my logic off or am I missing something?
It seams that this is an adequate solution to the PEM/PLOG and being cast it could still be ported if needed.
Has anyone tried the Dorman front manifold?
Also what do you think of this?
