TCCoA Forums banner

1 - 13 of 13 Posts

·
Registered
Joined
·
817 Posts
Discussion Starter #1
I swapped a 97 Mark motor into my 95 Bird and the IMRC'sare stuck shut. I know I have to get a window switch to make them work. Was just wondering how much of a difference do they really make on a stock motor with a tune.
 

·
Super Moderator
Joined
·
7,480 Posts
Well if they are stuck shut, you are losing a ton of top end power. With them deleted you will lose low end torque, but gain some on top. Unless you have a 3200+ stall converter and 4.10s, keep the IMRCs and make them work right.
 

·
Super Moderator
Joined
·
10,332 Posts
AFAICR, With them shut, the hp torque curve peaks around 3500Rs; opening them makes the peak shift to around 5500. (stock)

It has the overall effect of widening the torque/hp curve.
 

·
The Parts Guy
Joined
·
7,269 Posts
It's a noticeable difference. Also, there is no need to use a window switch. A cheaper RPM activated switch will do the job.
 

·
Super Moderator
Joined
·
11,961 Posts
It's a noticeable difference. Also, there is no need to use a window switch. A cheaper RPM activated switch will do the job.
yup good point...it's not like they have to close at any higher-RPM after they got open lol
 

·
Registered
Joined
·
570 Posts
What computer are you using to run the engine?

Not only are you leaving a bunch of HP on the table with the IMRC's closed, but I'll wager the tune isn't very good either.

BTW, The IMRC's open @ 3,000 RPM stock.
 

·
Registered
Joined
·
5,408 Posts
Fix them and get a rpm activated switch. With them closed the top end suffers, with them stuck open or deleted the low end suffers, even with a 3200 stall and 4.10s the low end could be improved, the only reason I would delete them is if it was force fed (turbo, sc) even then I would leave them unless they were showing a noticeable restriction or loss between 3000-3500.
 

·
Registered
Joined
·
1,910 Posts
Fix them and get a rpm activated switch. With them closed the top end suffers, with them stuck open or deleted the low end suffers, even with a 3200 stall and 4.10s the low end could be improved, the only reason I would delete them is if it was force fed (turbo, sc) even then I would leave them unless they were showing a noticeable restriction or loss between 3000-3500.
So I understand the function of the IMRC's, but is the MarkVIII the only car from Ford that used them? How did the Mustang Cobra's with the same block get their power? Can a 4.6 Cobra intake get put into a Mark VIII to help eliminate this problem area?
 

·
Registered
Joined
·
817 Posts
Discussion Starter #12
Im using the factory Birds computer and harness and the tune came from Lonnie at Blueovalchips. Someone was telling that some of the Birds have to have a Tach driver to run the regular RPM switch. I went to a local speed shop and the guy there said the digital one for around $110 wouldn't need one. Any truth to that? I knew the IMRC's not working would cause some difference in the hp/tq department but from what I,ve heard so far it sounds substancial. Thanks guys.
 

·
Registered
Joined
·
683 Posts
I deleted my IMRC's in my mark VIII because i just couldn't get them to open. below 3000 RPMs i have very little power, and my gas mileage is in the tank. When racing it rarely goes below 3000 RPMs anyways. last night i ran a 14.8 @ 95. before deleting the IMRCs i ran a 16.3 @ 85
 
1 - 13 of 13 Posts
Top