LM7 383 Build Up

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anyone have recommendations on an exhaust set up for this engine? shorty or long tube headers? I don't really want headaches with emissions stuff related to long tubes. I was kinda thinking shorty headers and split the exhaust at the y pipe junction to make it true duals with maybe an x-pipe.

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ttt.

Ordered the stroker kit. All forged Eagle stuff.

About half way done with the macine work on the block. Been working on my heads as well. Will post pics once I get my camera back!

[WARLOCK]

Keep us posted.

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Which compression ratio should I be shooting for on this motor? Stock compression ratio is about 10:1. What should I be shooting for on this motor?

Build Spec:
LM7 5.3 bored and stroked to 383ci
243 LS2 heads
LS6 Cam (405hp version)

using a Walboro 255lph and racetronix 38lb/hr @43.5 PSI & 44lb/hr @ 58 PSI injectors for fuel system upgrades.

Going in a 5000lb truck.
I want to run pump gas. preferably 87 octane, but I would go with 92 octane if the benefits were there.

Also would the stock 78mm throttle body be sufficient to supply airflow to this type of motor?

If I was to go with a bigger throttle body which one would you go with and would it need a different intake manifold?

Thanks for all the help guys!

[pl4yboy]

Which compression ratio should I be shooting for on this motor? Stock compression ratio is about 10:1. What should I be shooting for on this motor?

Build Spec:
LM7 5.3 bored and stroked to 383ci
243 LS2 heads
LS6 Cam (405hp version)

using a Walboro 255lph and racetronix 38lb/hr @43.5 PSI & 44lb/hr @ 58 PSI injectors for fuel system upgrades.

Going in a 5000lb truck.
I want to run pump gas. preferably 87 octane, but I would go with 92 octane if the benefits were there.

Also would the stock 78mm throttle body be sufficient to supply airflow to this type of motor?

If I was to go with a bigger throttle body which one would you go with and would it need a different intake manifold?

Thanks for all the help guys!

I'm still saying you need a bigger cam. You WOULD benifit from a 90mm intake big time, but to each his own. Also, run 91 at least. You can throw more timing at 91 than you can 87 and make more power. You'll get better fuel economy to offset the price. Also, for the money, grab some Pacesetter longtubes. Much much better than shorties.

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I'm still saying you need a bigger cam. You WOULD benifit from a 90mm intake big time, but to each his own. Also, run 91 at least. You can throw more timing at 91 than you can 87 and make more power. You'll get better fuel economy to offset the price. Also, for the money, grab some Pacesetter longtubes. Much much better than shorties.

If I was to go with a 90mm intake which manifold and throttle body would I want to use? I don't really want to get into anything super expensive like a FAST, but are any of the other GM truck or car manifolds and matching throttle bodies that would fit the bill with out modification to the throttle body wiring, etc?

On the note about the longtube headers. Wouldn't having longtubes throw codes on the computer and also decrease my mpg because of having no cats? I am trying to keep the truck emissions legal. They don't do any visual checks in WA state, just plug in the code reader and make sure you don't have any codes. I have no experience with long tube headers on fuel injected vehicles so the input is greatly appreciated.

[bangbangskeetskeet]

If I was to go with a 90mm intake which manifold and throttle body would I want to use? I don't really want to get into anything super expensive like a FAST, but are any of the other GM truck or car manifolds and matching throttle bodies that would fit the bill with out modification to the throttle body wiring, etc?

On the note about the longtube headers. Wouldn't having longtubes throw codes on the computer and also decrease my mpg because of having no cats? I am trying to keep the truck emissions legal. They don't do any visual checks in WA state, just plug in the code reader and make sure you don't have any codes. I have no experience with long tube headers on fuel injected vehicles so the input is greatly appreciated.

Yeah the TBSS comes with a 90mm TB and is also a good upgrade for the intake manifold. Depending on what year you're dropping this motor into you will have to fab a bracket if you're going to do a cable driven TB or either repin the PCM for a DBW TB or get the x-link...I haven't had any experience with it just heard about it.

Another option if you didn't want to go through that trouble you could just get an 80mm or 85mm DBC TB and have it ported and polished. Granted it's not a 90mm but it's still better than the stock 78mm unit.

As far as the longtubes that's ehat a tune is for. With the proper tuning the codes that would be set off by not having cats or the rear o2's are essentially turned off in the tune. I run the Pacesetter LT's and ORY with no cats into a single 3" in/out flowmaster and I have no codes and get about 17mpg on an average tank of gas. As far as getting better milage with having cats...I personally hvent ever heard that and honestly dont believe it. The cats are really just a restriction for the exhaust to flow.

Edit: You had also said you didn't want a higher rpm cam...the LS6 cam is exactly that. It makes power on the higher end. I am going to be installing one in my truck and will be shifting at 6300rpm. You really should look into a little larger cam or get a custom spec'd cam from someone.

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Its a dbw throttle body no cables.

so what year of TBSS intake and throttle body would I be looking for if I was to go that route?
or
suggestions on a ported stock style throttle body? BBK? (do ported TBs or like the BBK 80mm style need the manifold to be ported?

Thanks,
Ty

[thArf]

i have 6.0 injectors layin around if you need em

[pl4yboy]

Its a dbw throttle body no cables.

so what year of TBSS intake and throttle body would I be looking for if I was to go that route?
or
suggestions on a ported stock style throttle body? BBK? (do ported TBs or like the BBK 80mm style need the manifold to be ported?

Thanks,
Ty

Intake wise, you can go TBSS (Not sure what year is DBW on those) or a NNBS intake. The TBSS is 90mm, the NNBS is like 87mm. You can port your TB by yourself, its fairly easy. Or, you can have it sent to quite a few people to have it done cheaper than buying a BBK.