Gt4788
01-09-2012, 02:56 PM
#63
If the highest that you will be running is 20lbs the you wouldn't "need" to go with the 1/2" mod. But if you think that you might take it up pass 20psi. I would have it done. You never know what the future holds. If you called AES then you probably spoke to Fraser. He probably told you about the 1/2" process. All it is, they take your block and heads and drill the main head stud holes out to us a 1/2" bolt. Bigger bolt bigger threads more holding strength to keep the heads from lifting and pushing water.
I would have it done just to be safe. Not just give the ls9 head gasket and the arp hardwear a shot. Just to see when you push water. If you push it hard... and you're saying you are building this for the track mostly. Then you will push it hard enough to push water. So save yourself the time and trouble, get it done.
As far as doing this mod with the roating assembly already installed. Is the heads bolted to the block? Take it to some place that has experience with this. It is my understanding that they bolt the heads on to the block. Remove one stud at a time and drill then retread, clean and replace bolt. Until completed. Then it gets cleaned free of all the shavings. Again this is what I was told.
I am using Cometic MLS head gasket ls 4.130" x .040 and if you have the 1/2" mod you have to do the same to the head gasket.
I would have it done just to be safe. Not just give the ls9 head gasket and the arp hardwear a shot. Just to see when you push water. If you push it hard... and you're saying you are building this for the track mostly. Then you will push it hard enough to push water. So save yourself the time and trouble, get it done.
As far as doing this mod with the roating assembly already installed. Is the heads bolted to the block? Take it to some place that has experience with this. It is my understanding that they bolt the heads on to the block. Remove one stud at a time and drill then retread, clean and replace bolt. Until completed. Then it gets cleaned free of all the shavings. Again this is what I was told.
I am using Cometic MLS head gasket ls 4.130" x .040 and if you have the 1/2" mod you have to do the same to the head gasket.
01-09-2012, 05:46 PM
#64
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I was going to do it but my motor is already together and AES said they would need to pull it back apart... The roating assembly n heads so i will hold off on this ... We talked about doing a lsx block in the near future !!!! I like to gamble...lol everyone watch Alabama fuxk up lsu tonight!!! Hahha
01-09-2012, 07:04 PM
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thanks for guessing though
01-09-2012, 07:06 PM
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Thats 20 hp/lb of boost, which is on the other side of the map, yes, but still efficient to some degree. On most apps, we like to see 25hp/lb of boost when we are in the meat of the compressor map.
IAT delta and backpressure would really tell us if we were out of turbine, but with out knowing what those two numbers are, we can only speculate.
IAT delta and backpressure would really tell us if we were out of turbine, but with out knowing what those two numbers are, we can only speculate.
01-09-2012, 07:24 PM
#68
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01-09-2012, 08:52 PM
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here is my opinion. a 88mm is to small for a 408.. so putting the biggest ex housing on is not going to make it lag much more then any other one. just don't make the Y pipe to big 2 1/4" Y pipe is enough to make up to 2000 hp.and that GT47 would make more power and run better on a regular 6.0 liter
01-09-2012, 10:42 PM
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01-09-2012, 10:42 PM
#73
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here is my opinion. a 88mm is to small for a 408.. so putting the biggest ex housing on is not going to make it lag much more then any other one. just don't make the Y pipe to big 2 1/4" Y pipe is enough to make up to 2000 hp.and that GT47 would make more power and run better on a regular 6.0 liter
01-09-2012, 11:18 PM
#75
This is what I ran on my first setup a 410 with a GT5591 and the 1.00 ar.
If you look at garrets site the GT55 with the 1.00 ar flows the same # per hr as the 4788 with the 1.39ar. Thats why I said he should use the bigger housing. If you are clipping the wheel then you're compairing apples to oranges
If you look at garrets site the GT55 with the 1.00 ar flows the same # per hr as the 4788 with the 1.39ar. Thats why I said he should use the bigger housing. If you are clipping the wheel then you're compairing apples to oranges
Hey Los its been awhile since I've got to talk to you! Did you look at the link I put up on TINKERD dyno? He don't hit full boost until 4500RPM's and that's with a A/R .96 on the GT4788 408ci. How will the GT55 compare in your opinion on it coming into/hitting full boost at? I am interest to know what you think. You have been very helpful in the past for me. You and Josh@KY-Turbo is about the only 2 on here that I go too for opinions/advice.
I was all set on a GT5588 turbo until a friend of mine got one (Exile), its awesome on the track but very extreme. On the street the thing takes forever to spool & the new converter to make the turbo work right slips so much that the trans temps go sky high when you try to drive it on the street. He talked me out of a GT55 & into the GT4788. FWIW
High back pressure is going to make it push water easier.
GT5088 is something $100 more GT4788
Go bigger turbine before running a clipped wheel imo. It helps but Its not all about turbine flow, turbine leverage will make a big difference too.
Try to buy a turbo with an A/R that is in the middle of the range so that you can tailor it to your combo after it is running if need be. buying the smallest wheel and largest A/R leaves you no where to go if you need more flow and vice versa.
GT5088 is something $100 more GT4788
Go bigger turbine before running a clipped wheel imo. It helps but Its not all about turbine flow, turbine leverage will make a big difference too.
Try to buy a turbo with an A/R that is in the middle of the range so that you can tailor it to your combo after it is running if need be. buying the smallest wheel and largest A/R leaves you no where to go if you need more flow and vice versa.
If not limited to an 88mm for some class rules, I'd definitely get into a 91mm with those cubes.
01-09-2012, 11:43 PM
#80
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