90-92 vs 93-95 IHs

[LGAFF]

Question was posed to me about fitting 90-92 IHs on a 93-95.....what needs to be changed and is it worth it....I would think the move to 34mm gets you 80%+ of what you get from the 36mm port.

Thoughts?

[A26B]

The 90 housings are unique. This thread details the difference.

http://www.zr1.net/forum/showthread.php?t=13414&highlight=Injector+Housing

[XfireZ51]

Question was posed to me about fitting 90-92 IHs on a 93-95.....what needs to be changed and is it worth it....I would think the move to 34mm gets you 80%+ of what you get from the 36mm port.

Thoughts?

Lee,

=Jeff= has done this conversion. He felt it would be a way of getting the benefit of porting the top end without the porting. In doing the calc for the area of a circle, it comes out to 89% and since the volume of a cylinder is the area x the height, the % holds. Obviously the plenum would need to match the flow.

[-=Jeff=-]

Lee,

=Jeff= has done this conversion. He felt it would be a way of getting the benefit of porting the top end without the porting. In doing the calc for the area of a circle, it comes out to 89% and since the volume of a cylinder is the area x the height, the % holds. Obviously the plenum would need to match the flow.


I did 93-95 on a 90-92.. so the opposite of what Lee wants if I read it right

I added the plugs to the 93 IH as well to work on my 90.

I also have a later model plenum too

[LGAFF]

What about fuel injector issues...as in sealing there is a difference, correct?

[-=Jeff=-]

What about fuel injector issues...as in sealing there is a difference, correct?
yes.. on the primaries

but the 93-95 will work on the 90-92 just remove the o-ring on the bottom of the injector. you cannot use the 90-92 primary injectors on a 93-95 injector housing.

[VetteMed]

What Jeff said.... all correct. I am running 93-95 IHs on my 91.

[XfireZ51]

Oops. Sorry mis read Lee's post. Actually, Marc Haibeck usually does this conversion when he mods a 93-95 motor since the 90-92 IHs are more
available and they lend themselves to porting better than the later gen IHs.

[LGAFF]

I have someone interested in ported IHs but they have a later car, so sounds like my IHs would be plug and play

[LGAFF]

I guess on exchange that puts me in alittle bind as then I am stuck with older models and not many cars can use those...hmmmmm

[-=Jeff=-]

the end user would need the larger o-ring seals for the 90-92 IH though too

[A26B]

I'm a little confused, but nothing out of the ordinary for an old fart.

1. 90 IH's can be modified to work with 91~95 heads by drilling out the washer to 3/4" or removing it entirely. other than that, they are identical to 91~92 IH's.

2. 91~92 IH's can fit onto 93~95 heads without modification. Only need to remove lwr o-ring on the primary injectors & insure o-ring is in the IH for the primary injector.

Question: What are you thinking about exchanging? 375 Hp 90~92 IH's for 405 Hp 93~95 IH's? Remember, the 90 IH's can be easily modified to the same configuration as the 91~92 IH's.

Question: Are you saying the 90~92 IH's in stock condition have 34 mm ports compared to 36 mm ports on the 93~95 IH's.... or the other way around?

I guess on exchange that puts me in alittle bind as then I am stuck with older models and not many cars can use those...hmmmmm From this last post, it sounds like you are exchanging the opposite direction, your 93~95 IH's for customers 90~92 IH's.

[-=Jeff=-]

I'm a little confused, but nothing out of the ordinary for an old fart.

1. 90 IH's can be modified to work with 91~95 heads by drilling out the washer to 3/4" or removing it entirely. other than that, they are identical to 91~92 IH's.

2. 91~92 IH's can fit onto 93~95 heads without modification. Only need to remove lwr o-ring on the primary injectors & insure o-ring is in the IH for the primary injector.

Question: What are you thinking about exchanging? 375 Hp 90~92 IH's for 405 Hp 93~95 IH's? Remember, the 90 IH's can be easily modified to the same configuration as the 91~92 IH's.

Question: Are you saying the 90~92 IH's in stock condition have 34 mm ports compared to 36 mm ports on the 93~95 IH's.... or the other way around?

From this last post, it sounds like you are exchanging the opposite direction, your 93~95 IH's for customers 90~92 IH's.

I agree Jerry, that last post made me confused.

Also you can make the 91-95 IH work on the 90 with a freeze plug and a drill

[XfireZ51]

yes.. on the primaries

but the 93-95 will work on the 90-92 just remove the o-ring on the bottom of the injector. you cannot use the 90-92 primary injectors on a 93-95 injector housing.

So just switch to Accels. Probably need to do that anyway.

[Locobob]

Question: Are you saying the 90~92 IH's in stock condition have 34 mm ports compared to 36 mm ports on the 93~95 IH's.... or the other way around?



The 90-92 ports are roughly 33mm at the top of the injector housing.
The 93-95 castings are machined to roughly 34mm from the top to about halfway down the port.

[LGAFF]

I am asking if its really worth someone to go from a 34mm port to a set of my IHs that are ported to 36mm. The 93-95s breath well, I know about the oil control issues. My only concern was injectors fitting and if it was worth the $ for someone to swap 93-95s for a ported set of 90-92s

[Locobob]

I am asking if its really worth someone to go from a 34mm port to a set of my IHs that are ported to 36mm. The 93-95s breath well, I know about the oil control issues. My only concern was injectors fitting and if it was worth the $ for someone to swap 93-95s for a ported set of 90-92s

The late castings certainly have room for improvement in terms of both size and blending around the injector bosses. Whether or not its worth the money is up to the guy spending it, as you know horsepower doesn't come cheap on these cars.

[Jagdpanzer]

Lee,
I've ported the later 93-95 plenum and injector housings out to 36 mm
and the ports sure looked bigger than when I started. No doubt they wiil flow much better.