Hello all,
I have a question more out of curiosity. I am doing the 5.0 HO conversion in a '87 XR-7. The car was built in november of '86 and unfortuatly got stuck with the '86 engine. I have heard that the ports in the upper intake are bigger from '87 and on. Is this true? I plan on using the intake from the '89 GT, but like I said it was just out of curiosity. I need to know when I sell the left over stuff.
Yes the 87-93 had h.o cast into the intake under the cover plate on top. the lowers are the same.
Well the HO upper (used in 87-93 Mustangs and Mark VIIs) has a bigger throttle body opening. The ports between the upper and lower intakes are the same. BTW the 5.0 SO and HO lowers are identical so there is no point in using the Mustang's it's the same as yours.
the 86' mustang HO or at least some of them had the standard upper intake or at least wasnt stamped HO. they had the bigger tb though.....the one i encountered was on a local guys 86. its hard to go soly by something like that given its a 20 year old car and who knows what happens too a car in 20 years....
i dont think the regular upper and the HO upper are all that differint anyway and wouldnt make all that much of a differance. i think port matching the bigger tb to the SO intake would be good enough in terms of using the stock intakes.....
on the other hand, the 87 up HO intakes are so easy too find and so cheep i cant see bothering with all that.....
The bigger upper will make a slight difference withbetter heads than the stock E6's. The real bottleneck in the system is the lower. Great info on how to fix it is here: http://www.tmossporting.com/TechArticles/WhyPortaLowerIntake/tabid/328/Default.aspx
Not likely, my '86 Grand Marquis that was built 7/86 had a '87 engine(plug wires said 1987, and the car used the 3057 tail lamps instead of the 1157)... The '87 model year started in Aug '86 so again a '86 engine ain't likely. It really makes no difference as '86-'87-'88 Bird/Coug 5.0s are virtually identical.