Cam for twins
05-13-2008, 12:27 AM
#1
Cam for twins Well, I've been away from this section of the site for a while since I was having so much fun driving it. One of the few remaining Jelly APE motors finally lost oil pressure..so I have a new on on order and set for delivery next thursday.
Because I think its the cam bearings, I want to get a cam on order incase it was damaged. The swap day is set in stone and I'm on limited time and want to have a shaft on hand in case.
So, whats the deal today, discussion still the same.. some like reverse spilt, some like small duration and low lift.. whats hot, whats proven?
Engine: 415 ci iron block with ported 6.0 heads, 8.5 to 1 compression with twin t4 60-1 turbos.
Thinking a 234-230 reverse split .585 ish lift on a 114.
Problem is theres more too it, different lobes etc. i 'm just looking for input?
Because I think its the cam bearings, I want to get a cam on order incase it was damaged. The swap day is set in stone and I'm on limited time and want to have a shaft on hand in case.
So, whats the deal today, discussion still the same.. some like reverse spilt, some like small duration and low lift.. whats hot, whats proven?
Engine: 415 ci iron block with ported 6.0 heads, 8.5 to 1 compression with twin t4 60-1 turbos.
Thinking a 234-230 reverse split .585 ish lift on a 114.
Problem is theres more too it, different lobes etc. i 'm just looking for input?
05-13-2008, 12:54 AM
#2
Nothing seems to be proven. Different opinions about reverse split, no split, normal split.
Different opinions about lsa, lift not so much.
I think its generally agreed more lift will give more power but too much lift is pain as you will be changing out valve springs maybe pretty often like maybe every 20,000 or 30,000 miles if you are over 600 lift. And changing valve springs is not enjoyable on fourth gen f bodies.
Bigger lsa give nicer idle less lope .Not totally sure what bigger lsa does to torque and powerband.
There seems to be a lack of any real independent dyno testing on this subject as well. Sure you see lots of turbo car smaking big power with this cam or that cam but turbo cars make big power period some even with stock cams.
I picked a cam for a few of the above reasons. Went with lift under 600 by a bit. Should be around 580. Went with big lsa. I want nice smooth non lopey idle. Went with pretty mellow duration especially when you consider its in a 408.
For me think this will be fine cam. Not going to sweat it too much. Sure my turbo kit and 408 will make more power than I could every use on the street and my car is a street car.
Seems you start going big and you lose driveabilty.Car has nothing down low or surges and just is a pain to tune,etc. I am not really that happy with my current cam and its pretty mild compared to many. Current cam is a 221/221/558/558/114 lsa as my 408 is not in car yet. I have 1.8 yella terra rockers going in the 408.
Different opinions about lsa, lift not so much.
I think its generally agreed more lift will give more power but too much lift is pain as you will be changing out valve springs maybe pretty often like maybe every 20,000 or 30,000 miles if you are over 600 lift. And changing valve springs is not enjoyable on fourth gen f bodies.
Bigger lsa give nicer idle less lope .Not totally sure what bigger lsa does to torque and powerband.
There seems to be a lack of any real independent dyno testing on this subject as well. Sure you see lots of turbo car smaking big power with this cam or that cam but turbo cars make big power period some even with stock cams.
I picked a cam for a few of the above reasons. Went with lift under 600 by a bit. Should be around 580. Went with big lsa. I want nice smooth non lopey idle. Went with pretty mellow duration especially when you consider its in a 408.
For me think this will be fine cam. Not going to sweat it too much. Sure my turbo kit and 408 will make more power than I could every use on the street and my car is a street car.
Seems you start going big and you lose driveabilty.Car has nothing down low or surges and just is a pain to tune,etc. I am not really that happy with my current cam and its pretty mild compared to many. Current cam is a 221/221/558/558/114 lsa as my 408 is not in car yet. I have 1.8 yella terra rockers going in the 408.
05-13-2008, 01:17 AM
#3
good reply! Tahnks. my main concern is ehich cam lobe to choose and how to evaluate valve events to choose specs more wisely. And to get one ordered tomorrow!
I had good luck with the EDC reverse split.. so I'm tempted to keep it that way. My car is 4000 lbs and an auto with a 3800 ish converter... if it matters.
I had a fair amount of backpressure with old cam... 11lb spring was 13.5 lbs .
I had good luck with the EDC reverse split.. so I'm tempted to keep it that way. My car is 4000 lbs and an auto with a 3800 ish converter... if it matters.
I had a fair amount of backpressure with old cam... 11lb spring was 13.5 lbs .
Last edited by Jammer; 05-14-2008 at 05:01 PM.
05-13-2008, 01:56 AM
#4
TECH Apprentice
Nothing seems to be proven. Different opinions about reverse split, no split, normal split.
Different opinions about lsa, lift not so much.
I think its generally agreed more lift will give more power but too much lift is pain as you will be changing out valve springs maybe pretty often like maybe every 20,000 or 30,000 miles if you are over 600 lift. And changing valve springs is not enjoyable on fourth gen f bodies.
Bigger lsa give nicer idle less lope .Not totally sure what bigger lsa does to torque and powerband.
There seems to be a lack of any real independent dyno testing on this subject as well. Sure you see lots of turbo car smaking big power with this cam or that cam but turbo cars make big power period some even with stock cams.
I picked a cam for a few of the above reasons. Went with lift under 600 by a bit. Should be around 580. Went with big lsa. I want nice smooth non lopey idle. Went with pretty mellow duration especially when you consider its in a 408.
For me think this will be fine cam. Not going to sweat it too much. Sure my turbo kit and 408 will make more power than I could every use on the street and my car is a street car.
Seems you start going big and you lose driveabilty.Car has nothing down low or surges and just is a pain to tune,etc. I am not really that happy with my current cam and its pretty mild compared to many. Current cam is a 221/221/558/558/114 lsa as my 408 is not in car yet. I have 1.8 yella terra rockers going in the 408.
Different opinions about lsa, lift not so much.
I think its generally agreed more lift will give more power but too much lift is pain as you will be changing out valve springs maybe pretty often like maybe every 20,000 or 30,000 miles if you are over 600 lift. And changing valve springs is not enjoyable on fourth gen f bodies.
Bigger lsa give nicer idle less lope .Not totally sure what bigger lsa does to torque and powerband.
There seems to be a lack of any real independent dyno testing on this subject as well. Sure you see lots of turbo car smaking big power with this cam or that cam but turbo cars make big power period some even with stock cams.
I picked a cam for a few of the above reasons. Went with lift under 600 by a bit. Should be around 580. Went with big lsa. I want nice smooth non lopey idle. Went with pretty mellow duration especially when you consider its in a 408.
For me think this will be fine cam. Not going to sweat it too much. Sure my turbo kit and 408 will make more power than I could every use on the street and my car is a street car.
Seems you start going big and you lose driveabilty.Car has nothing down low or surges and just is a pain to tune,etc. I am not really that happy with my current cam and its pretty mild compared to many. Current cam is a 221/221/558/558/114 lsa as my 408 is not in car yet. I have 1.8 yella terra rockers going in the 408.
-----------------------------------------
dyno tested and drag raced several combo's
237/237 @ 114 cam on 355 tt sbc , was twin 57mm's ,
engine went 1016 / 960 ( hp/tq) , with a cam swop to 256/245 @ 114 , both cams where flat tappet, and .510 max lift....
the 256/245 cam's made no more gross hp BUT tq contined to flat line on dyno sheet for extra 300-400m rpm
no difference in spool !!
57mm's had stg 3 turbine housing with .82 a/r
drag car went 7.4 @ 184
swopped out the 57's to twin 61's
61mm's had stg 5 turbine wheel and .82 a/r
next i tried a roller cam
this roller , 258/258 @ 114 , was changed out from 256/245 @ 114 flat tappet, same twin 61's , same fuel system, same boost etc...
the car went from 7.4 @ 184 to 7.2 @ 191mph ( 156 mph @ 1/8 )
roller cam had .625 lift , about .100" more than flat tappet.
the turbo change from 57 to 61 was about 100-130 hp each...
the cams didnot show much improvement, the turbo's showed the hp increase
the reverse split cams are not for everyone
they are mainly for higher exhaust backpressure systems
have seen good flowing exhausts relish with increased exhaust duration to intake dur...
each engine suits its own set up
larger lob sep , 'calms" down the idle , and decreases the peak value of the hp, BUT increases the range of the power, or in other words, increases the average hp across the rpm range.
dyno results with our engines show less max hp with higher lob sep cams, BUT better average hp across the dyno graph.
last cam install in twin 76mm 358 sbc, was 276 / 265 @ .050 with 116 lob sep. lift was .685 with jesel shaft rockers, 1.6 : 1
had small exhaust housings to spool up turbo, as no nos was allowed in class run.
idled like a stock...
hope this helps
ash
06-03-2008, 08:13 PM
#6
If so, what is the engine displacement?
How does it idle?
Is the drivability good?
I was looking at a cam for my TT, LS1 (iron block) 408, with L92 heads...going in a 69 Camaro for pro-touring...so it needs to sound naaaaasty!
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06-05-2008, 10:51 PM
#14
On The Tree
-----------------------------------------
dyno tested and drag raced several combo's
237/237 @ 114 cam on 355 tt sbc , was twin 57mm's ,
engine went 1016 / 960 ( hp/tq) , with a cam swop to 256/245 @ 114 , both cams where flat tappet, and .510 max lift....
the 256/245 cam's made no more gross hp BUT tq contined to flat line on dyno sheet for extra 300-400m rpm
no difference in spool !!
57mm's had stg 3 turbine housing with .82 a/r
drag car went 7.4 @ 184
swopped out the 57's to twin 61's
61mm's had stg 5 turbine wheel and .82 a/r
next i tried a roller cam
this roller , 258/258 @ 114 , was changed out from 256/245 @ 114 flat tappet, same twin 61's , same fuel system, same boost etc...
the car went from 7.4 @ 184 to 7.2 @ 191mph ( 156 mph @ 1/8 )
roller cam had .625 lift , about .100" more than flat tappet.
the turbo change from 57 to 61 was about 100-130 hp each...
the cams didnot show much improvement, the turbo's showed the hp increase
the reverse split cams are not for everyone
they are mainly for higher exhaust backpressure systems
have seen good flowing exhausts relish with increased exhaust duration to intake dur...
each engine suits its own set up
larger lob sep , 'calms" down the idle , and decreases the peak value of the hp, BUT increases the range of the power, or in other words, increases the average hp across the rpm range.
dyno results with our engines show less max hp with higher lob sep cams, BUT better average hp across the dyno graph.
last cam install in twin 76mm 358 sbc, was 276 / 265 @ .050 with 116 lob sep. lift was .685 with jesel shaft rockers, 1.6 : 1
had small exhaust housings to spool up turbo, as no nos was allowed in class run.
idled like a stock...
hope this helps
ash
dyno tested and drag raced several combo's
237/237 @ 114 cam on 355 tt sbc , was twin 57mm's ,
engine went 1016 / 960 ( hp/tq) , with a cam swop to 256/245 @ 114 , both cams where flat tappet, and .510 max lift....
the 256/245 cam's made no more gross hp BUT tq contined to flat line on dyno sheet for extra 300-400m rpm
no difference in spool !!
57mm's had stg 3 turbine housing with .82 a/r
drag car went 7.4 @ 184
swopped out the 57's to twin 61's
61mm's had stg 5 turbine wheel and .82 a/r
next i tried a roller cam
this roller , 258/258 @ 114 , was changed out from 256/245 @ 114 flat tappet, same twin 61's , same fuel system, same boost etc...
the car went from 7.4 @ 184 to 7.2 @ 191mph ( 156 mph @ 1/8 )
roller cam had .625 lift , about .100" more than flat tappet.
the turbo change from 57 to 61 was about 100-130 hp each...
the cams didnot show much improvement, the turbo's showed the hp increase
the reverse split cams are not for everyone
they are mainly for higher exhaust backpressure systems
have seen good flowing exhausts relish with increased exhaust duration to intake dur...
each engine suits its own set up
larger lob sep , 'calms" down the idle , and decreases the peak value of the hp, BUT increases the range of the power, or in other words, increases the average hp across the rpm range.
dyno results with our engines show less max hp with higher lob sep cams, BUT better average hp across the dyno graph.
last cam install in twin 76mm 358 sbc, was 276 / 265 @ .050 with 116 lob sep. lift was .685 with jesel shaft rockers, 1.6 : 1
had small exhaust housings to spool up turbo, as no nos was allowed in class run.
idled like a stock...
hope this helps
ash
