Compression for my 408 with this cam...too low?
Thread Starter
TECH Apprentice
Joined: May 2006
Posts: 308
Likes: 0
From: Nebraska
Compression for my 408 with this cam...too low? Ok, I'm a little stuck with my LS2 street/strip build- my current setup will have compression of 10.3:1 SCR/7.75 DCR using the parts I own. Conventional thinking is higher compression works better w/ bigger cams, so the potential to improve my setup is there...question is how much HP& Tq will raising the compression actually get me?.. My problem is the cam that I have is a tweener really...and to get higher SCR (like to 11:1) I would have to buy different heads. Before I consider buying different heads and/or cam....interested to know what everyone thinks about the current set-up I have and if raising the compression (with diff heads) or buying a smaller cam will make that big of a difference for my situation...I want under the curve street performance 1st...w/occasional trip to track 2nd..
Currently the set up below gives me 10.3:1 SCR 7.75 DCR:
408 Cid
PRC CNC Heads 227cc w/72cc chambers
240/244 cam .609/.612 114LSA on 109ICL
3600 stall
A4
3.71 gears
LT dual exhausts
I don't want to mill my heads and risk the intake ports and bolts not matching after that...
My other simple option would be to get a smaller cam...
Currently the set up below gives me 10.3:1 SCR 7.75 DCR:
408 Cid
PRC CNC Heads 227cc w/72cc chambers
240/244 cam .609/.612 114LSA on 109ICL
3600 stall
A4
3.71 gears
LT dual exhausts
I don't want to mill my heads and risk the intake ports and bolts not matching after that...
My other simple option would be to get a smaller cam...
Launching!
Joined: Jan 2010
Posts: 238
Likes: 1
From: Houston TX
im looking at a 408 my self still doin homework on heads and cam combos, now i have 93 every were down here in houston, i have talked to alot of people about it and have came up with 11.8:1 static comp and 8.3:1 dynamic comp,
i am still trying to figure out what is a good dynamic comp, without getting any pre ignition/detonation ,, i have heard 8.5 dynamic is max on 93 pump.
i am still trying to figure out what is a good dynamic comp, without getting any pre ignition/detonation ,, i have heard 8.5 dynamic is max on 93 pump.
Go smaller on the cam and tighter on the lsa.
If you go with a 236/240 111+4 that should get you dcr up to a little over 8 and only bring the overlap up from 14* to 16* and you power band will be around 300rpm lower.
If you go with a 236/240 111+4 that should get you dcr up to a little over 8 and only bring the overlap up from 14* to 16* and you power band will be around 300rpm lower.
Thread Starter
TECH Apprentice
Joined: May 2006
Posts: 308
Likes: 0
From: Nebraska
99Bluz28
...that's in line with what I'm thinking....smaller cam, advance it to close intake sooner and raise DCR to around 8.2....my SCR will still be low at 10.3 but pump gas friendly for sure....wonder how much power I'm really leaving on the table with a 10.3 scr vs 11+ compression and this setup..???
...that's in line with what I'm thinking....smaller cam, advance it to close intake sooner and raise DCR to around 8.2....my SCR will still be low at 10.3 but pump gas friendly for sure....wonder how much power I'm really leaving on the table with a 10.3 scr vs 11+ compression and this setup..???
Thread Starter
TECH Apprentice
Joined: May 2006
Posts: 308
Likes: 0
From: Nebraska
A reputable sponsor on this website recommends a 231/239 113+4 cam which would change my DCR to 8.02....the power band advertised for this cam is 2000-7000 rpms...
Next size bigger is the 235/243 113+4....2200-7200....
and then 99Bluz28's 236/240 111+4 recommendation...
Am I splitting hairs at this point and/or does anyone see a clear cut advantage with any of the 3 mentioned above? All are smaller and therefor probably better for my particular set-up...question is which one?
.
Next size bigger is the 235/243 113+4....2200-7200....
and then 99Bluz28's 236/240 111+4 recommendation...
Am I splitting hairs at this point and/or does anyone see a clear cut advantage with any of the 3 mentioned above? All are smaller and therefor probably better for my particular set-up...question is which one?
.
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Verdad Gallardo A reputable sponsor on this website recommends a 231/239 113+4 cam which would change my DCR to 8.02....the power band advertised for this cam is 2000-7000 rpms...
Next size bigger is the 235/243 113+4....2200-7200....
and then 99Bluz28's 236/240 111+4 recommendation...
Am I splitting hairs at this point and/or does anyone see a clear cut advantage with any of the 3 mentioned above? All are smaller and therefor probably better for my particular set-up...question is which one?
.
Next size bigger is the 235/243 113+4....2200-7200....
and then 99Bluz28's 236/240 111+4 recommendation...
Am I splitting hairs at this point and/or does anyone see a clear cut advantage with any of the 3 mentioned above? All are smaller and therefor probably better for my particular set-up...question is which one?
.
Thread Starter
TECH Apprentice
Joined: May 2006
Posts: 308
Likes: 0
From: Nebraska
THanks 99Bluz28
I went with the smallest cam (231/239) knowing that in my other engine (418/LS3) I have a 236/242 and also still the 240/244 on the shelf.
THanks to all who posted, appreciate your insights...
Drive safe
Stroker2112
I went with the smallest cam (231/239) knowing that in my other engine (418/LS3) I have a 236/242 and also still the 240/244 on the shelf.
THanks to all who posted, appreciate your insights...
Drive safe
Stroker2112
