Thread: Franklin S4 centreline

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2011-05-05 23:34:43

moles

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Franklin S4 centreline

Did anyone who tried franklin stage 4's measure the drop in centreline? And on top of that did anyone try advancing the intake cam by much to bring the power down a bit seeing as the big lobes don't make much power below about 7K? It seems that even though the FS4 has similar lift to the N1 but more duration it was retarded a lot from the factory N1 centreline.

Thanks in advance

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2011-05-06 02:37:12

BlueRB240

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5speed set up mine but they were 1st stage 4's, I'm not sure how different they are now. It was something crazy like +12 on the intake but I can't remember off the top of my head. Might have to wait for 5speed to comment he might remember.

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2011-05-06 02:51:02

moles

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Thanks BlueRB240. I was hoping you might have had something to say. As far as I know the grind is still the same so any info 5 speed has would be appreciated! I found mine to be -10 on stock settings rather than + so not sure if that's what you're thinking.

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2011-05-06 19:00:36

KillerKrossover Online/offline status of KillerKrossover is unknown

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If you go to "original" SR20forum you will see a lot of threads about the FS4. Do a search for lobe center. SR20 Forum - Search Results

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2011-05-06 23:08:16

moles

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Thanks 5speed. I found this:

Originally Posted by nick

Originally Posted by SR20Turbofreak

Originally Posted by SR20Turbofreak View Post
the centerlines on the FS4 cams that i got were pretty far off from optimal in my book for making power.
typically, SR's and VE's like to see about 100 deg IN and about 105 EX C/L.

N1 cams are at 104 and 110 and work well drop in.
std VE are at 104 IN and 114 EX. you can gain a few WHP by retarding the EX cam on the std ve cams.

the N1's work best at about +4 -4 - +5 -5 give or take, that puts them to about 99-100 deg IN and 105-106 DEG EX.

the FS4 cams that I measured were 115 IN and 100 EX? i think off the top of my head or somewhere around there. almost like they got mixed up. The only way I'd run cams like this is on a very hihg RPM turbo motor with large displacement. but that tells me that the EX cam is too small and the intake is too big.

I would run the FS4 cams at straight up 0,0, then run the intake cam advanced 1 whole tooth, and from there retard it about 5-6 deg. the exhaust i'd advance about 6 to start with.

personally i think if they had so much RnD on these cams to start with they would have dyno tested them before selling them and found what lobe centers they work best with.

I talked to him very breifly about CL's when i talked to him the other day. From what i understand their de cams are using similar CL's. I know when the were developing the cams they brought a motor and measured the stock cams in the motor. i.e the specs at the valve.
What determines where your centerline should be? if thats not a really stupid question. To me what i know about Cam timing (albeit limited) it makes sense that they make so much power up top, why is it that an engine "likes" a certain range of CL's?

In this thread: Franklin S4's Centerline Theory - SR20 Forum

Last edited by moles on 2011-05-06 at 23-11-59.

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2011-05-06 23:43:51

moles

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I am going to start with a 104-105 CL on the FS4 Intake high and 108 on the N1 Exhaust high giving a LSA of about 107degrees and on the low lobes intake will be 20V CL at 114 and exhaust 20V CL at 114. Should be as good a place to start as any based on peoples experience. If anyone has any other advice please let me know

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2011-05-08 07:34:33

nick m

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sounds good, the franklin low lobes are fucking attrocious, I got mine Cam doctored and the seat to seat duration on the low lobes was only a few degrees smaller than the high lobes! The low lobe ramps are huge!
Should have listened to 5 speed in the first place, he warned me!

Keen to see how your setup goes

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2011-05-08 09:25:17

moles

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Yeah it's a bit of a mission! Mine are 20V low lobes so different issues to the original stage 4's. Hopefully get it all back together within a couple of weeks and see how it goes.

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2011-05-08 11:29:10

chapnutz1

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i ran my FS4's straight up in my turbo VE, car was breathing very well and made just under 400 on 11psi at 6800rpm where i had ignition problems.

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2011-05-08 15:56:32

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jer_760

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Originally Posted by nick
sounds good, the franklin low lobes are fucking attrocious, I got mine Cam doctored and the seat to seat duration on the low lobes was only a few degrees smaller than the high lobes! The low lobe ramps are huge!
Should have listened to 5 speed in the first place, he warned me!

Keen to see how your setup goes

Was this with the original version or the newest one?

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