My Turbo LS1 Trans-Am build

Junk86

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Just give your car to Marty, and blank check, and a few weeks later you will get a car that will push your own dick in upon lift off

Lol....I can do that. But I really don't need a blank check. Unless your super generous. If you have any questions I'll be glad to help..Or if you want it done..I can turn it around for you super quick too for a good price.
 

willizm

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May 13, 2009
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Hell, i don't know. I'm on the fence with the whole which heads to use thing. I picked up some 317's pretty cheap so I don't feel like I have to use them, but I'm still leaning toward it. I hear the benefits less chance for detention, pushing a little more boost and they flow pretty good being the favorable reason to use the 317's. This is the first time I've heard of lag using the 317's. I'm no where near the level you, eagle or Brandon are with experience on turbo ls1's, but I wouldn't mind hearing some debate over it. This isn't going to make or break my build as the heads only cost me $130.
 

Eagle

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Hell, i don't know. I'm on the fence with the whole which heads to use thing. I picked up some 317's pretty cheap so I don't feel like I have to use them, but I'm still leaning toward it. I hear the benefits less chance for detention, pushing a little more boost and they flow pretty good being the favorable reason to use the 317's. This is the first time I've heard of lag using the 317's. I'm no where near the level you, eagle or Brandon are with experience on turbo ls1's, but I wouldn't mind hearing some debate over it. This isn't going to make or break my build as the heads only cost me $130.

I don't have any "lag" with my 317s... but my motor is completely stock short of the turbo... so I don't expect anything crazy from it without boost involved. :dunno:

93 all year, up to 15psi, no knock... until my converter started chattering. Dropped 100 in to go to 17-18psi and knock was still AOK.

I can't complain. But I hear what Marty is saying. I just wish I had the $$$$ to toss @ bigger heads.
 

Eagle

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The only reason to really go to "bigger" heads is for the thicker deck, which in theory allows for more boost to be pushed... but you're not going big boost now.

I couldn't keep my ported 241's (that actually flowed more than 243s - yes I had them flow tested) because of my -4cc forged pistons bumped my CR too high. So I HAD to do something about my CR.

You could run the 241s.... but I'd personally go for the 317s for the added security they provide. But I like to play safe, just ask Brandon. :rofl:
 

willizm

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Yeah, down the road if I get a forged 370 iron block and ditch the ls1 then I will look at better heads, but figure these would do me good for now. I turn to them internets to find good info, but unfortunately the more I read and ask, the more i get conflicting info. Not trying to say anyone is wrong or right, but many ways to skin the same cat I suppose.
 

Pressure Ratio

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Glen Ellyn
Heads will have little effect on "lag" as far as the turbo and building boost goes. The cam, turbo turbine wheel/housing has more to do with that than the head port size. The off boost performance would have more to do with that added compression. Just like a n/a motor the extra compression will make the motor be more "snappy" when out of boost. Some thing desirable with a car that sees a lot of street use.

I would agree with sticking with what you have. Once you decide it is time to step up buy an aftermarket head for the reasons already posted.
 

Pressure Ratio

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bet yes, you can ask 100 people and get 100 different answers on how they would do it.

I am very budget oriented. haha I like to do more with as little cash as possible. I don't see any issue with running what you have is all I am saying. The tuning window from a 9:1 motor versus a 9.5:1 motor is not that bad at all. If you were talking 11:1 I would say yes, tuning would be much more critical. lol
 

willizm

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Stock ls1's are 10.1:1. If I add these heads I'd be around 9.5:1. If I run stock heads with a stock bottom end at around 10-12lbs then would I benefit and be safer by dropping the compression by adding the 317 heads? I'm also adding into the equation that I'm doing the arp rod bolts and head studs to help keep things together. From what I read and hear the bottom ends weakest point are really those bolts when pushing a little over 8lbs. It's added insurance replacing them no doubt.
 

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Glen Ellyn
The heads could go either way. I guess you should ask your tuner what he wants for compression. I don't think 10:1, or for sure 9.5:1, is that high at all. Especially at those low boost numbers. Sluggish off boost performance sucks on a street car. Because on the street you are going to be out of boost way more than you will be in boost. So off boost performance should be considered for sure.

We have 10:1 & higher motors with 8-12# of boost living fine. One that gets beat daily and has 50K miles since the blower install. Still runs great. Tuning is key for sure.

The hardware I do not see as a bad investment by any means.
 

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Glen Ellyn
Got a pair of 317 heads off of a member on ls1tech pretty cheap. They look like they are in really good condition in the photos I've seen. We'll see when I get them.
Sorry, I have ADD or some thing. I didn't read you already picked up 317s for cheap. Just going back and re reading the thread. If any one of the heads you have need nothing done to them just take your pick. lol
 

Junk86

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Yeah, down the road if I get a forged 370 iron block and ditch the ls1 then I will look at better heads, but figure these would do me good for now. I turn to them internets to find good info, but unfortunately the more I read and ask, the more i get conflicting info. Not trying to say anyone is wrong or right, but many ways to skin the same cat I suppose.

Well in this case...nobody is wrong or right. Its all about what you wanna spend. I was just trying to save you money untill you could buy some nice heads. I don't agree with the whole theory of the 317 head on a low boosted application..but to each is own. Dyno results don't lie, and I have had machinists look at the decks, and their is not much different deck thickness from a 317 to a 241. But there is on the 853 -317. just sayin. You guys can't always believe what you read.
 

Junk86

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Heads will have little effect on "lag" as far as the turbo and building boost goes. The cam, turbo turbine wheel/housing has more to do with that than the head port size. The off boost performance would have more to do with that added compression. Just like a n/a motor the extra compression will make the motor be more "snappy" when out of boost. Some thing desirable with a car that sees a lot of street use.

I would agree with sticking with what you have. Once you decide it is time to step up buy an aftermarket head for the reasons already posted.


That was my point. With the small boost he was going to run..the extra compression would make for more street friendly car...with instant boost!! You'll be just fine.
 

Junk86

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Fuck that. I'd not go to that trouble! But your call I suppose!

You've got head studs too, so you're already pulling the heads regardless. You just need a decision - 241 or 317.

Another good option so you can seal those heads up and turn the wick up some more would be to go with the LS9 head gaskets. The are remarkable with their sealing capabilities. 7 layer compared to 3.
 

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