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JAKEJR
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Joined: 07 Apr 2007
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Location: MERRILLVILLE, INDIANA
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 Posted: Mon Apr 09, 2007 5:42 pm Post subject: |
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| 96capriceMGR wrote: | I know no matter how many times I post this not on how many forums I post it I will never get people to see reality but the LT4 ports arfe NOT raised .100 they are .100 taller. The stock LT1 port is about 170cc the LT4 more like 190-195, all round bigger and taller as opposed to the raised most often claimed by those who just read magazines as opposed to make fast cars.
Here is a comparison picture http://i85.photobucket.com/albums/k54/gumplt1/DCP_1456.jpg
Edelbrock is claiming a blistering 3-7hp gain from the LT1 intake  .
If you think the LT4 stuff is all that then go for it but when someone who does things right don't wonder why they are faster.
Don't want to take my word for it read this http://ls1tech.com/forums/showthread.php?t=432878 pay particular attention Ed Wright's posts, he is the original LT1 tuner and considered by most other tuners to be at the very top of their field.
What people who want to modify cars need to learn is that there is a signifigant difference between what is said to be best and what is actually best and marketing is usually the difference. The guys doing things right are too busy DOING THINGS RIGHT to be spending a lot of effort on advertizing.
I know I am coming across as a pushy jerk but my intent is to stop people from making mistakes. |
I believe what we're dealing with here is the use of two different terms to described much the same thing. Some say six, others say half a dozen.
For example, the posts I've read and responded to regarding guys "adjusting their valve lash" or adjusting their "lash", when, in fact with a hydraulic cam, they're actually adjusting lifter preload. Another one is LCA vs LSA; there are others but I think I made my point; at least I tried.
From all I'll the posts I've read from those who have actually had their LT4 dynoed, their engines put out more than GM's advertised HP rating of 330 HP and opposed to the LT1's rating of 300. Of course, this is after subtracting the percentage of driveline loss (here again is another disputed area) of from 15% to 21%.
To me, bottom line is GM made a LOT of changes when they went from LT1 to LT4, not merely the cylinder heads and intake manifold. To look at the list of things GM changed and to say that those changes only resulted in 30 more HP than the LT1 is questionable at best. So my thinking is either the LT1 was over-rated or the LT4 was under.
So what I'm saying, in effect, is rather one calls it "raised .100" or ".100 taller", for practical purposes, we're talking about the same thing. The parts aren't directly interchangable, that is, without mods.
But rather than kick this around 'forever', I'm ready to move on to something more beneficial, like who makes a NARROW BODY, SELF-ALIGNING, 1.65 roller rocker for the LT1.
Anyone know?
Jake |
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Big Dave
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Joined: 04 Dec 2005
Posts: 2656
Location: Tampa Florida
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| Posted: Mon Apr 09, 2007 6:42 pm Post subject: |
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Crane makes all of GM's alumium rockers rockers including the 1.6:1 std width on the LT4. They also make narrow self guided (Vortec style) rockers in aluminum; as does CompCams (Isky has self guided in a variety colors but they all appear to be the wide body style rockers).
Big Dave |
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JAKEJR
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Joined: 07 Apr 2007
Posts: 17
Location: MERRILLVILLE, INDIANA
1003.14 points
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| Posted: Mon Apr 09, 2007 6:59 pm Post subject: |
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| Big Dave wrote: | Crane makes all of GM's alumium rockers rockers including the 1.6:1 std width on the LT4. They also make narrow self guided (Vortec style) rockers in aluminum; as does CompCams (Isky has self guided in a variety colors but they all appear to be the wide body style rockers).
Big Dave |
Right, I found those already. Anything on 1.65s though?
I found them made by Scorpion, but they're wide/normal body and I need the narrow stuff to clear the center bolts on the covers.
Jake |
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Big Dave
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Posts: 2656
Location: Tampa Florida
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| Posted: Mon Apr 09, 2007 7:07 pm Post subject: |
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Personally I would stick with the name brands for two reasons. First the unknown vendors usually buy their stock from people like Crane or Comp who actually manufacture these parts from raw materials. Second they are not as likely to have the engineering expertise to stand behind their product when you discover the spring hits the fulcrum at max lift because they shifted the pushrod cup to get that advertised 1.65:1 ratio when there is so little difference between a 1.5 and a 1.6 that it takes a dyno to sort it out.
If lift is that critical go with a chromemoly CompCams Big Block rocker at 1.7:1 by using ARP 7/16" studs. It will clear a 1.55" dia spring at 0.750" lift and give you all the added lift and duration your motor could ask for.
Big Dave |
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JAKEJR
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Joined: 07 Apr 2007
Posts: 17
Location: MERRILLVILLE, INDIANA
1003.14 points
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| Posted: Mon Apr 09, 2007 7:19 pm Post subject: |
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| Big Dave wrote: | Personally I would stick with the name brands for two reasons. First the unknown vendors usually buy their stock from people like Crane or Comp who actually manufacture these parts from raw materials. Second they are not as likely to have the engineering expertise to stand behind their product when you discover the spring hits the fulcrum at max lift because they shifted the pushrod cup to get that advertised 1.65:1 ratio when there is so little difference between a 1.5 and a 1.6 that it takes a dyno to sort it out.
If lift is that critical go with a chromemoly CompCams Big Block rocker at 1.7:1 by using ARP 7/16" studs. It will clear a 1.55" dia spring at 0.750" lift and give you all the added lift and duration your motor could ask for.
Big Dave |
If got a set of CompCams 1.6, SA narrow body rockers on hold right now from J&J; just looking for other ioptions before I close the deal.
Your BB suggestion is interesting, but I suspect I'd still have cover bolt clearance problems. I use to run FORD rockers on a 468 CID BB Chevy I put in my Trans Am just to pick up .5 in the ratio; they bolted right up.
But I'm beginning to believe I'm pretty much stuck with getting narrow body rockers. Best I've found so far is 1.6s.
If I installed a set of aftermarket heads with the dual valve cover bolting system, I could go with them, buy perimeter covers and BINGO! Of course, that's opening yet another can of worms.
Jake |
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96capriceMGR
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Joined: 23 Aug 2003
Posts: 814
Location: New London Wisconsin
20327.88 points
1996 Chevrolet Caprice
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| Posted: Mon Apr 09, 2007 9:48 pm Post subject: |
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| I am running non-SA Comp ProMagnum widebody rockers which takes about 3 minutes per valvecover to do the modification for and that includes finding the tools. I don't know anything though. |
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af2
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Joined: 01 Sep 2003
Posts: 5565
Location: grassvalley, ca
71429.36 points
1933 Willys Coupe
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| Posted: Mon Apr 09, 2007 10:21 pm Post subject: |
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| 96capriceMGR wrote: | | I am running non-SA Comp ProMagnum widebody rockers which takes about 3 minutes per valvecover to do the modification for and that includes finding the tools. I don't know anything though. |
You know you're car 60s at 1.46 and mine will do better when I get the converter.  |
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JAKEJR
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Joined: 07 Apr 2007
Posts: 17
Location: MERRILLVILLE, INDIANA
1003.14 points
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| Posted: Mon Apr 09, 2007 10:42 pm Post subject: |
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| 96capriceMGR wrote: | | I am running non-SA Comp ProMagnum widebody rockers which takes about 3 minutes per valvecover to do the modification for and that includes finding the tools. I don't know anything though. |
So, you're saying you're running 1.6 wide bodys on an LT1 with no valve cover interference at the cover bolts; did I read that correctly?
Jake |
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