LT4 Heads!!!
08-12-2007, 09:12 PM
#6
Especially with stock or near stock displacement you will be better off with ported stock heads than LT4s.
Here is where people will get pissy. From what I have seen even on a stroker most people are best served by ported stock castings over LT4s even ported. The LT4 intake is no upgrade either, internally it is the same as the later LT1 intakes it just has more material above the port to seal the taller LT4 head ports, the intake does not come close to matching them though.
Here is where people will get pissy. From what I have seen even on a stroker most people are best served by ported stock castings over LT4s even ported. The LT4 intake is no upgrade either, internally it is the same as the later LT1 intakes it just has more material above the port to seal the taller LT4 head ports, the intake does not come close to matching them though.
08-13-2007, 12:09 AM
#7
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i run an lt4 w lt4 hotcam kit in my TA for 50k now 320hp at the wheels through a 4l60e and 342's stock tune
my recomendation buy some cores off ebay and spend 2500 to get them ported insted of the lt4 kit
this is who i get my stuff done by, highly recomend them there building my 396 w stage3 lt1 heads
http://gtp-racing.com/
my recomendation buy some cores off ebay and spend 2500 to get them ported insted of the lt4 kit
this is who i get my stuff done by, highly recomend them there building my 396 w stage3 lt1 heads
http://gtp-racing.com/
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08-13-2007, 12:48 AM
#9
Originally Posted by socal
i run an lt4 w lt4 hotcam kit in my TA for 50k now 320hp at the wheels through a 4l60e and 342's stock tune
08-13-2007, 03:28 AM
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Right on..so get the stockers ported out and roll with those...got it. Next question...The stocks on my 97 LT1, aluminum or iron??? if Iron, what difference would aluminum make?
08-13-2007, 04:50 PM
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If you can get them cheap i would go lt4's mod for mod a lt4 head will always outflow a lt1 head at any lift. Being they have identical port work. A good shop can get 300cfm out of LT4's. That and the 58cc with also bump the compression up a tad and make more power
08-14-2007, 08:45 AM
#17
Originally Posted by 396D1SS
If you can get them cheap i would go lt4's mod for mod a lt4 head will always outflow a lt1 head at any lift. Being they have identical port work. A good shop can get 300cfm out of LT4's. That and the 58cc with also bump the compression up a tad and make more power
Some of us understand that flow or dyno numbers do not necessarily equal performance. Apparently you have not yet learned that leason.
08-14-2007, 07:25 PM
#19
Well the theory is more as cast performance and to some degree that is the case if you rev high enough.
One of the "Stock Eliminator" guys here says that as cast for as cast he gained a tenth. Now keep in mind Stock Eliminator is cars with as cast intakes and heads and stock TBs running deep in the 10s and shifting higher than our pcm will support.
When you start comparing cars with ported LT4s vs. properly ported LT1s though I fail to see an advantage, not even on a stroker.
I know people will talk about port volume and such and yes for a bigger engine or one revving very high port volume is something to be considered, I just think if you pay attention to performance numbers you will see adequate port volume is smaller than most would have you believe.
A couple months back I think it was GMHTP had an article on the EFI shootout and there were two LTx cars listed with details, a LOT of similarities between the cars, most notable differences were one had worked LT4 heads and several points more compression then the other with AI 200cc LT1 castings. The LT1 car ran more duration and if memory serves a lot less lift. They ran about the same times, both have managed 9.9 on aftermarket computers and very low 10s on stock computers.
The LT4 owner driver is a legend and undisputed racing and tuning guru, so it does not come down too experiance.
I will see if I can come up with what issue it was.
One of the "Stock Eliminator" guys here says that as cast for as cast he gained a tenth. Now keep in mind Stock Eliminator is cars with as cast intakes and heads and stock TBs running deep in the 10s and shifting higher than our pcm will support.
When you start comparing cars with ported LT4s vs. properly ported LT1s though I fail to see an advantage, not even on a stroker.
I know people will talk about port volume and such and yes for a bigger engine or one revving very high port volume is something to be considered, I just think if you pay attention to performance numbers you will see adequate port volume is smaller than most would have you believe.
A couple months back I think it was GMHTP had an article on the EFI shootout and there were two LTx cars listed with details, a LOT of similarities between the cars, most notable differences were one had worked LT4 heads and several points more compression then the other with AI 200cc LT1 castings. The LT1 car ran more duration and if memory serves a lot less lift. They ran about the same times, both have managed 9.9 on aftermarket computers and very low 10s on stock computers.
The LT4 owner driver is a legend and undisputed racing and tuning guru, so it does not come down too experiance.
I will see if I can come up with what issue it was.