383 Stroker Rev Limit
02-25-2016, 07:10 AM
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383 Stroker Rev Limit This is my first post on the Forum so, please, be gentle...
I had a 383 stroker built on an LS1 block. All forged rotating assembly, Trick Flow 220 heads (57cc chamber?), aggressive cam etc etc etc...
The initial tuner did not put a rev limit into the programming. In fact, he wasn't sure what it should be.
So, in consideration of the higher velocity of the pistons at higher RPM, does anyone know what would be an appropriate rev limit?
Second, the builder estimated the compression to be about 11.5:1 and that he could tune it to burn 93 pump gas. Well, it actually is just north of 12:1 and does not like 93 octane! It detonates under load. I'm thinking (a dangerous pass time - I know) that I should mix 93 and race fuel to get the octane up. Your thoughts please?
Thanks in advance!
I had a 383 stroker built on an LS1 block. All forged rotating assembly, Trick Flow 220 heads (57cc chamber?), aggressive cam etc etc etc...
The initial tuner did not put a rev limit into the programming. In fact, he wasn't sure what it should be.
So, in consideration of the higher velocity of the pistons at higher RPM, does anyone know what would be an appropriate rev limit?
Second, the builder estimated the compression to be about 11.5:1 and that he could tune it to burn 93 pump gas. Well, it actually is just north of 12:1 and does not like 93 octane! It detonates under load. I'm thinking (a dangerous pass time - I know) that I should mix 93 and race fuel to get the octane up. Your thoughts please?
Thanks in advance!
Last edited by Jeff McAllister; 02-25-2016 at 07:42 AM.
02-25-2016, 07:51 AM
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Call the person who built the motor and ask him what it should be. When you build a motor, that is one of the critical things that determine a lot from crank, rod, and piston selection to cam profile, valve springs, pushrods, etc.
02-25-2016, 08:18 AM
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The tune is going to be redone on a dyno here locally.
It's along story, but the shop that built the engine has not disclosed who they got the short block from (I've asked several times). I have the specs.
It's been a frustrating experience, to say the least...
It's along story, but the shop that built the engine has not disclosed who they got the short block from (I've asked several times). I have the specs.
It's been a frustrating experience, to say the least...
02-26-2016, 09:09 AM
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When I bought a forged LS3 stroker 419 from Livernois Motorsports, I also asked what the rev limit was. I was told "whatever the valve train can handle".
In a stroker the cylinder volume increases without any increase in the valve size, resulting in cylinder filling problems at high RPM. In short, strokers don't rev as well as non-strokers.
Even with a 239/251 cam I fell that power drops after 6500 and therefore see no advantage to shifting past 7000 with the rev limit set at 7100.
In summary, about 7000 sounds about right to me too and even if your valve train can handle it, you probably won't get much, if any, benefit revving past 7000.
Just my opinion; I'm a barely a novice in this area.
In a stroker the cylinder volume increases without any increase in the valve size, resulting in cylinder filling problems at high RPM. In short, strokers don't rev as well as non-strokers.
Even with a 239/251 cam I fell that power drops after 6500 and therefore see no advantage to shifting past 7000 with the rev limit set at 7100.
In summary, about 7000 sounds about right to me too and even if your valve train can handle it, you probably won't get much, if any, benefit revving past 7000.
Just my opinion; I'm a barely a novice in this area.
02-26-2016, 01:19 PM
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Thank you - that really helps.
We changed the heads to Trick Flow 220's. I'm not sure if the valve faces are any larger or not. We certainly beefed all of the valve train components up...
We're going to out it on the dyno and re-tune the engine. I suspect I'll have much better information after that.
Thanks again for your post.
Jeff
We changed the heads to Trick Flow 220's. I'm not sure if the valve faces are any larger or not. We certainly beefed all of the valve train components up...
We're going to out it on the dyno and re-tune the engine. I suspect I'll have much better information after that.
Thanks again for your post.
Jeff