I am in the middle of rebuilding the lower intake on my svt to go on my 3.0 oval port,, i have it all apart and can't decide if i want to drill and retap the 4 butterfly screws that were jacked up or just cap the ends and go without them,, i know they help alot on the 2.5 but the 3.0 will have a slightly better lower torque curve naturally because it is slightly bigger. i just can't make up my mind,, also just like throttle but optimizing would it help to put in countersunk screws and cut them to length. just something i am dealing with wanted some opinions
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Still can't decide on secondaries
- Thread starter LLADNAR
- Start date
Based on what I have read the secondaries still help with low end torque even on the 3L. Yes, optimizing them will have a positive effect if you have the time and patience to do it. I say, if you have plenty of time to work and are in no rush to get the car back on the road keep the 2nd's and optimize them. .02
Bradness
CEG'er
I've been told that when dynoing a 3.0, the double hump in the curve disappears. This would seem to suggest that the secondaries were really necessary for the 2.5 to make decent HP/TQ but really not req'd for a 3.0.
I do have a LIM from an early (pre 00) Sable and it also has the IMRC c/w secondaries. Then Ford changed both the upper and lower. Could this have been done for cost effectiveness, HP/TQ or some other reason?
Where I come from, the cams and intake are designed to work together. You didn't mention what cams you're using.
Is a single or dual plenum better? How about plenum volume?
I do have a LIM from an early (pre 00) Sable and it also has the IMRC c/w secondaries. Then Ford changed both the upper and lower. Could this have been done for cost effectiveness, HP/TQ or some other reason?
Where I come from, the cams and intake are designed to work together. You didn't mention what cams you're using.
Is a single or dual plenum better? How about plenum volume?
Last edited:
warmonger
Hard-core CEG'er
Secondaries still help the 3L engine in the low range, even with ovalport heads. I've got plenty of datalogs now that are showing this to be the case.
It is between 8-10% decrease in load in the 3000 rpm range when the secondaries are NOT in or are pinned open.
I can't prove that pulling them increases load in the upper rpm range. If your IMRC box&linkage are working then use them.
You will stillhave enough torque on a 3L without them to drive just fine though so if you choose to lose them then just keep the rev's up anyway.
It is between 8-10% decrease in load in the 3000 rpm range when the secondaries are NOT in or are pinned open.
I can't prove that pulling them increases load in the upper rpm range. If your IMRC box&linkage are working then use them.
You will stillhave enough torque on a 3L without them to drive just fine though so if you choose to lose them then just keep the rev's up anyway.