What are everyone's thoughts on big cams and loss of low end?
#21
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I went and printed off both runs.. looks like I was wrong on what it made last time. Both runs are with my 370 with 2 valve relief flat top pistons, pulls are done in 2nd gear, converter is very loose as you can see in the graph that it finally come in around 44-4500 rpm
243 heads milled .030, 244/248 .612/.615 112 lsa, Vic Jr 1375 cfm 4150 Throttle body. Peak tq (316) is around 5700 rpm, I believe it would have made more if i would have taken it on to 71-7200 rpm.
241 heads-small port work, 230/226 .597/.56x 113 lsa, Prod Prod 85MM Intake and Throttle body. Peak tq (292) is around 5100 rpm and Hp peaked around 6000.
243 heads milled .030, 244/248 .612/.615 112 lsa, Vic Jr 1375 cfm 4150 Throttle body. Peak tq (316) is around 5700 rpm, I believe it would have made more if i would have taken it on to 71-7200 rpm.
241 heads-small port work, 230/226 .597/.56x 113 lsa, Prod Prod 85MM Intake and Throttle body. Peak tq (292) is around 5100 rpm and Hp peaked around 6000.
Last edited by dirt track racer 81; 07-20-2009 at 05:17 PM.
#22
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I went from a little peanut flat tappet comp cam to a LT4 hot cam (218/228 duration and 112 lsa) and I really can't tell a bit of difference in lowend. At times the LT4 cam actually feels stronger and may very well be. It lugs beautifully and I have a 4L80E with the stock diesel converter that only stalls to 1500 rpms. I think most of the lag in the lowend can be cured by adding a little timing in the 70-100kpa and 0-2000 rpm range. Mine responded very well to it anyway. I do have a dual plane intake still but I think the tunnel ran effect of a single plane high rise might make the lowend even stronger yet.
#23
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heres my only dyno graph I have so far. I will be returning once I get the money for dyno time and seeing what the end result is. Ran out of fuel at 5200 RPM
this is a 6.0 with a 221/221 .558 114. I have a donkey dick cam I will be installing once funds return. I will have more of an opinion about big vs smaller cams after that but currently I think its really based on LSA and duration. I would love more duration and smaller LSA in hopes of more gains over all. I honestly dont notice much of a "power loss" down low unless AC is on. Then again who doesnt? Also you've got a "big-ish" cam for a 5.3.
this is a 6.0 with a 221/221 .558 114. I have a donkey dick cam I will be installing once funds return. I will have more of an opinion about big vs smaller cams after that but currently I think its really based on LSA and duration. I would love more duration and smaller LSA in hopes of more gains over all. I honestly dont notice much of a "power loss" down low unless AC is on. Then again who doesnt? Also you've got a "big-ish" cam for a 5.3.
#24
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bingo
ok so here is my story...
5.3 stock cam with a tbss stall = 1.88 60'
LS1 stock cam with a tbss stall = 1.88 60'
ls1 226 112 cam with tbss stall = 1.88 60'
swapped converters for a 1.69 60'
ls1 231/239 111+2 same converter 1.75 in + 2000 DA. im sure it will cut 1.69 again in the good weather
i think MOST of your 60' is in the converter and tires/suspension. NOT your cam.
ok so here is my story...
5.3 stock cam with a tbss stall = 1.88 60'
LS1 stock cam with a tbss stall = 1.88 60'
ls1 226 112 cam with tbss stall = 1.88 60'
swapped converters for a 1.69 60'
ls1 231/239 111+2 same converter 1.75 in + 2000 DA. im sure it will cut 1.69 again in the good weather
i think MOST of your 60' is in the converter and tires/suspension. NOT your cam.
#25
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I think big cams are a waste of time unless you bump up the compression. Like already stated, you need to keep the DCR up or else the cam is a dog down low. Thats how it was on my old camaro. The dcr was around 7.5 and it was a little soggy below 3k. It wasnt that bad cuz the maro is much lighter than a truck and its 5.7 instead of a 5.3.
#26
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I think big cams are a waste of time unless you bump up the compression. Like already stated, you need to keep the DCR up or else the cam is a dog down low. Thats how it was on my old camaro. The dcr was around 7.5 and it was a little soggy below 3k. It wasnt that bad cuz the maro is much lighter than a truck and its 5.7 instead of a 5.3.
I've never heard that one before. Even the 221 in my 4.8 wasnt bad because it pulled like a son of a bitch up top. I wouldnt have changed that cam for anything in the 4.8. I wouldnt have gone any bigger tho.
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Stock LQ4 with 02 LS6 Cam
204/218 .555/.551 117.5
204/218 .555/.551 117.5
The base line is all stock with:
- edelbrock shorty headers
- K&N FIPK
- Magna Flow Muffler Dumped
All Gains were in tuning.... Well Worth the $350
Third Gear Pull With Converter Locked
The fan Kicked On In The Middle of The Pull
- edelbrock shorty headers
- K&N FIPK
- Magna Flow Muffler Dumped
All Gains were in tuning.... Well Worth the $350
Third Gear Pull With Converter Locked
The fan Kicked On In The Middle of The Pull
Here you can see the drop in low end, @ 3000 i am pulling 45 more tq
for a gain of only 25 hp...
could it be just the cam? would a custom cam of EQUAL duration, lsa etc bring back some low end?