The old LS3 vs LS7 debate
Discussion
The merits of LS3s and LS7s have been discussed a few times, opinion seems to be a built LS3 is not only likely to be more powerful than a standard LS7, but also cheaper.
Now I'm looking for between 6-700hp and ideally I'd like it quite revvy. To me the LS7 is the obvious starting point, but they're still expensive. A standard LS3 is approximately half the price.
The car will spend quite a lot of it's time at trackdays, and reliability is the most important criteria for me.
So, what are the pro's and con's of building a 427 LS3 vs an LS7 with the above type power? Which will be the most reliable, which will be most cost effective.
Not interested in comments about not needing that type of power, it's what I want. I don't need to do a lot of things I'm doing during the build, but it's how I want it, so just facts please.
Cheers
Now I'm looking for between 6-700hp and ideally I'd like it quite revvy. To me the LS7 is the obvious starting point, but they're still expensive. A standard LS3 is approximately half the price.
The car will spend quite a lot of it's time at trackdays, and reliability is the most important criteria for me.
So, what are the pro's and con's of building a 427 LS3 vs an LS7 with the above type power? Which will be the most reliable, which will be most cost effective.
Not interested in comments about not needing that type of power, it's what I want. I don't need to do a lot of things I'm doing during the build, but it's how I want it, so just facts please.
Cheers
Kyles a good ladto speak to on this one, i went for a hotcam ls3 from partsworld, im being told both by partsworld and Kyle that 530hp to 550hp should be easily achieved.
Now im told all in a supercharger system will set me back anythign from 3k to 5k. So pound per HP id have to say LS3, but this is only from a buying point of view, the techinicals youll have to get from the guys that really know what they are doing with these.
good luck
Now im told all in a supercharger system will set me back anythign from 3k to 5k. So pound per HP id have to say LS3, but this is only from a buying point of view, the techinicals youll have to get from the guys that really know what they are doing with these.
good luck
To the best of my knowledge, 600bhp is straightforwardly do-able on both LS3 and LS7 (the LS3 being a lot more modified obviously).
According to a lot of US crate engine sites, around 650bhp is achievable on a 7, but I've not seen any performance stats / UK rolling road graphs to verify these numbers.
To get the magic n/a 100bhp/litre something like a Kinsler intake is required.
At the same capacity the LS3 will be a longer stroke engine to the LS7 with the LS7 having the power slightly higher up the rev range.
I'm not sure how price wise a more standard yet supercharged LS3 type engine would compare (and I don't mean the LS9)...
Just some thoughts to get you started
According to a lot of US crate engine sites, around 650bhp is achievable on a 7, but I've not seen any performance stats / UK rolling road graphs to verify these numbers.
To get the magic n/a 100bhp/litre something like a Kinsler intake is required.
At the same capacity the LS3 will be a longer stroke engine to the LS7 with the LS7 having the power slightly higher up the rev range.
I'm not sure how price wise a more standard yet supercharged LS3 type engine would compare (and I don't mean the LS9)...
Just some thoughts to get you started
For tracking and 'revvy motor' requirements go with shorter stroke, if you are geared for track use you will enjoy it better. Longer strokes and big capacities give great torque and power figures but generally live longer at lower rpm (say 6500rpm as a regular max).
Even though the LS motors are a huge improvement over the old small block a revvy version would still benefit from some uprated valve train. GM have done some great hydraulic race lifters which are used with success up to 8000rpm.....they are reasonably priced from some suppliers too. Quality valve springs and maybe some Yella Terra shaft rockers would help. There's a company that manufactures aftermarket sump hinges and baffles to suit LS pans too. Lots of great cylinder head options out there. When the rest of your engine spec is finalized get a custom cam man to sort your grind....much better results than shelf grinds IME.
Maybe a specification-built unit would be more suited to your listed requirements.
However Gm also do a crate LS3 515HP....really designed for the drag guys as it can be run on a carb but you can fit either a fly by wire or mechanically operated throttle body to the supplied inlet manifold..
Get the exhaust system (particularly headers) matched to cope with your proposed (real HP) output and give lots of attention to the installation.
Should be a very nice combo and last well if properly thought out....its the overall package that brings wins and smiles not just numbers on dyno sheets.....even if you wanted 1000hp it would still have to be well matched to work !
Good Luck.
Even though the LS motors are a huge improvement over the old small block a revvy version would still benefit from some uprated valve train. GM have done some great hydraulic race lifters which are used with success up to 8000rpm.....they are reasonably priced from some suppliers too. Quality valve springs and maybe some Yella Terra shaft rockers would help. There's a company that manufactures aftermarket sump hinges and baffles to suit LS pans too. Lots of great cylinder head options out there. When the rest of your engine spec is finalized get a custom cam man to sort your grind....much better results than shelf grinds IME.
Maybe a specification-built unit would be more suited to your listed requirements.
However Gm also do a crate LS3 515HP....really designed for the drag guys as it can be run on a carb but you can fit either a fly by wire or mechanically operated throttle body to the supplied inlet manifold..
Get the exhaust system (particularly headers) matched to cope with your proposed (real HP) output and give lots of attention to the installation.
Should be a very nice combo and last well if properly thought out....its the overall package that brings wins and smiles not just numbers on dyno sheets.....even if you wanted 1000hp it would still have to be well matched to work !
Good Luck.
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