Exhaust Manifolds..
- Thread starter UnseenSHO
- Start date
Disclaimer: Links on this page pointing to Amazon, eBay and other sites may include affiliate code. If you click them and make a purchase, we may earn a small commission.
Most everything I have read on the forum say no, they are not restrictive. Were they may not be tuned like a set of headers they will not hold you back with other simple bolt on mods. It the rest of the exhaust that needs work, the Y is the worst part.
Phoenix
SHOHOLIC
Truth , they are actually pretty good for manifolds , the exit on each side is approx 2" if I recall , and thats pretty good. Thats why the headers will come in the very end of your mods.
93rev2sev
SHO Member
You can port match the heads to the manifolds...that would be productive.
jedhead
New Member
SHO Shop extruded honed a set of exhaust manifolds and lost 10 - 15lbs of torque all across the rpm band.
Bob
Bob
I will expell more useless knowledge . . . . there is a certain Ford specialist/one time (still?) SHO tuner who would sometimes machine out the 1.9 inch OD at the merge to 2.0 inches. You will find the ATX manifolds have this inner diameter already. I would only consider it of you have 2.25 inch pipes going from manifolds to cats.
If you do this please kindly measure before/after dyno gains . . . zak
If you do this please kindly measure before/after dyno gains . . . zak
Last edited:
I bet a S/C SHO would like a extrude exhaust manifold...
The stock manifolds are not a restriction at all. Loss of tq from SHOshop indicates that. Extrude honed makes them flow that much better, in fact too good. The stock manifolds are tuned for mid-range power, they are designed extremely well. Its half the reason why nobody can make a aftermarket header that out performs the stock manifold. Want to try something unique? Get another 3.0L front manifold (One that bends around the oil filter) replace the back manifold so that you now have two equal length manifolds. Now install dual exhaust with a x pipe and I bet you will have a runner!
One could expect stock cams to produce more top end power = to that of a stage 2 cam + the stock bottom...
O, all stock manifolds are about 1.9 inch collector. Doesn't matter if you have a 3.2 or 3.0
The stock manifolds are not a restriction at all. Loss of tq from SHOshop indicates that. Extrude honed makes them flow that much better, in fact too good. The stock manifolds are tuned for mid-range power, they are designed extremely well. Its half the reason why nobody can make a aftermarket header that out performs the stock manifold. Want to try something unique? Get another 3.0L front manifold (One that bends around the oil filter) replace the back manifold so that you now have two equal length manifolds. Now install dual exhaust with a x pipe and I bet you will have a runner!
One could expect stock cams to produce more top end power = to that of a stage 2 cam + the stock bottom...
O, all stock manifolds are about 1.9 inch collector. Doesn't matter if you have a 3.2 or 3.0
Last edited:
We found out some time ago that porting only the collectors makes a big difference on a blown or gassed engine.
In my '89, I picked up a tenth of a second in the qtr mile by porting the collectors.
In my '89, I picked up a tenth of a second in the qtr mile by porting the collectors.
What size collector are we talking about? How did it effect the curve, and do you have a dyno graph?
No dyno graphs, just time slips. Went from 13-teens to 13-ohs with the save crappy 60-foots. Picked up speed on the big end too. That says more acceleration, more power under the graph at the top end of the scale.
I have to disagree completely. I had two different sets of headers hand made for me when I was into SHO's. one set was very long and ended at the rear section of the subframe ( for the front ) and they connected in a Y right under the shifter. This set gained 10HP right out of the box. I had the dyno sheet for it but its long gone now. When I dyno'd the car I was seeing a vaccum pull at full throttle. Unknown at the time but my throttle cable had stretched and I was not getting full throttle.
The second set I had made was half the length and I had even better results from that set. Alas I never had that set Dyno'd before I sold them and then sold the car. At this point I did have a different computer control system ( the piggy back chip programed by a laptop ).
Doug does or used to port the collector with good results. IMHO the manifold is not hte best design. It starts out with, I think, 1 7/8" collectors then shrink to about 3/4" or so at the collector. So naturally when you EH the entire manifold you are bloating the already odd dimensions and I assume that it kills the scavenging. The headers I had made I THINK had an 1 5/8" primary all the way down to the collector.
the engine set up I had was a 3.2, Je 9:1 pistons, PNP heads/intake, Stage II cams BB butterflies ect.
The second set I had made was half the length and I had even better results from that set. Alas I never had that set Dyno'd before I sold them and then sold the car. At this point I did have a different computer control system ( the piggy back chip programed by a laptop ).
Doug does or used to port the collector with good results. IMHO the manifold is not hte best design. It starts out with, I think, 1 7/8" collectors then shrink to about 3/4" or so at the collector. So naturally when you EH the entire manifold you are bloating the already odd dimensions and I assume that it kills the scavenging. The headers I had made I THINK had an 1 5/8" primary all the way down to the collector.
the engine set up I had was a 3.2, Je 9:1 pistons, PNP heads/intake, Stage II cams BB butterflies ect.
Similar threads
Latest posts
-
-
-
-
-
Finally Upgrading After 18 Months Of Ownership- Latest: Texas Marauder
