Gears vs Power... (opinions wanted)
Okay, I'm thinking about that 402 from SLP. With a decent cam (230/236 .575 114LSA) and good heads (warmed up 6.0 ones) I figure it should make an honest 425-450rwhp and some absurd rwtq around 550 or so.
With a normal weight of around 5300lbs (appx) my truck should run [email protected] MPH. OR around 8.6 in the 1/8th mile around 85mph.
Anyway, I did some math with the gearing of the 4L60E and shit as well as with what gears I'm looking at either the 4.10:1 or 4.56:1. Well with a 4.56:1 I'd be into 3rd gear in the 1/8th already and cross the traps around 4000rpm in the 1/8th. If I still went on to run a 1/4 I'd cross around 4900rpm...If I ran a 4.10:1 I'd be around 5800rpm in the 1/8th which is better than 4000rpm. I don't want to rev to 6600rpm in a truck even if I have the cam to support it...I have a 402, it's got TQ out the ass I don't need topend HP.
From my memory you want to be at the top of the powerband when going through the traps and a 4.10:1 would be about 600rpm less in the 1/4 vs a 4.56:1 but I could honestly give a shit about running to 110mph in a big truck.
So it looks like a set of 4.10:1 gears would be better for the drags AND economy... :think:
With a normal weight of around 5300lbs (appx) my truck should run [email protected] MPH. OR around 8.6 in the 1/8th mile around 85mph.
Anyway, I did some math with the gearing of the 4L60E and shit as well as with what gears I'm looking at either the 4.10:1 or 4.56:1. Well with a 4.56:1 I'd be into 3rd gear in the 1/8th already and cross the traps around 4000rpm in the 1/8th. If I still went on to run a 1/4 I'd cross around 4900rpm...If I ran a 4.10:1 I'd be around 5800rpm in the 1/8th which is better than 4000rpm. I don't want to rev to 6600rpm in a truck even if I have the cam to support it...I have a 402, it's got TQ out the ass I don't need topend HP.
From my memory you want to be at the top of the powerband when going through the traps and a 4.10:1 would be about 600rpm less in the 1/4 vs a 4.56:1 but I could honestly give a shit about running to 110mph in a big truck.
So it looks like a set of 4.10:1 gears would be better for the drags AND economy... :think:
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Sleeper said:
Well that won't go in for a while... so until then it needs to be at its optimum. The 33" tires w/ 3.73:1 gears isn't enough as it drags ass at 70mph...it's about 1800rpm, 4.10:1 would be about 2050rpm. NICE jump to cruise in the power band.
Economy is very possible with a performance vehicle, the '01 C5 I used to own averaged around 25mpg...
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Z71mudder said:
They are $3500 new from SLP.
Install prolly $1200 or so if I paid someone. Just tune your existing PCM. Sleeper said:
It's all about efficiency...I'll post up a graph of it I tossed together on DD2K to give you some ideas about how much TQ it makes.
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Z71mudder said:
Yes, shortblock only but it's all new. The rotat assy is $2500..by the time you machine a 6.0 block and put it together it'd cost ya more.
Indeed, all you existing bits will swap right over from your 4.8, 5.3, 6.0, etc.
Here's that post for the dyno charts - http://www.gmfullsize.com/forum/showthread.php?t=10009
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word, just posted there. So, lets say you got the 402 shortblock, swapped in all your factory 5.3 stuff, heads etc, w/ some porting polishing etc in the process, and got a custom tune for this, w/ intake and complete exhaust, what kinda power would you be putting out?
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Z71mudder said:
Hrm, well over 400hp for sure. The cam is what's going to help that 402 a lot, if you ran the stock 5.3 cam it'd prolly wheeze out around 4000rpm :jester:
It's going to make some stout TQ is why I love it so much, and cheaper than a Radix and about the same as an STS...
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