Discussion
Stumbled across this article, which makes interesting reading. Looks like the LS3 block maybe the way to go....
www.camarohomepage.com/ls3/index.htm
www.camarohomepage.com/ls3/index.htm
Pretty much all the blocks so far have been proven to silly power levels. So for the most part its largely irrelevant.
But obviously if it isnt any extra cost, its nice to have what is potentially the best. As to whether that will offer any benefits to your specific build...is another matter.
The only thing I'd have against the LS3, is the larger bore sizes. The smaller the bore-bore wall thickness, the less chance the head gasket has of sealing. It may be a small amount....but every little helps !!
And unless its a n/a build....taking capacity to its limits, really isnt necessary.
But obviously if it isnt any extra cost, its nice to have what is potentially the best. As to whether that will offer any benefits to your specific build...is another matter.
The only thing I'd have against the LS3, is the larger bore sizes. The smaller the bore-bore wall thickness, the less chance the head gasket has of sealing. It may be a small amount....but every little helps !!
And unless its a n/a build....taking capacity to its limits, really isnt necessary.
Agree on the capacity Stevie, my only thought was if you have a set of custom pistons made and say a 3.8" stroke you could still retain a decent skirt height, have a better rod/stroke ratio than a 4" stroke and still have a bit more capacity with the larger bore. Purely conjecture though.
I dont really see the skirt as an issue unless turning high rpm.
Again, regardless of stroke...bore wall thickness can become an issue in terms of HG sealing in FI builds. So in those cases, the extra bore size isnt needed, or even wanted over 4.0"
The 4.0" stroke is debatable. Ive used it for a long time, and the difference in torque over a std stroke is very welcome. But that also boils down to the build.
With a centri like mine, that little bit extra can be nice. With a PD style blower, its probably pointless, so maybe better to stick with std or a shorter stroke than 4"
Turbo's....hard to say as there are so many options with regards to boost/spool etc. But the extra bore thickess would definately be nice to have there.
But either way, unless pushing extremes, all of the LS platform engines have proven themselves very reliable when built correctly.
Doesnt matter what block/crank/rod etc combo there shouldnt really be any problems.
Again, regardless of stroke...bore wall thickness can become an issue in terms of HG sealing in FI builds. So in those cases, the extra bore size isnt needed, or even wanted over 4.0"
The 4.0" stroke is debatable. Ive used it for a long time, and the difference in torque over a std stroke is very welcome. But that also boils down to the build.
With a centri like mine, that little bit extra can be nice. With a PD style blower, its probably pointless, so maybe better to stick with std or a shorter stroke than 4"
Turbo's....hard to say as there are so many options with regards to boost/spool etc. But the extra bore thickess would definately be nice to have there.
But either way, unless pushing extremes, all of the LS platform engines have proven themselves very reliable when built correctly.
Doesnt matter what block/crank/rod etc combo there shouldnt really be any problems.
Rev it until it doesnt wanna rev any higher 
The last 383 went to about 7300, although usually shifted around 6800.
This 403 will go to 7k, but its a little lazier. So generally shift around 6500-6800 now.
just depends really.
Lookin at the graph from Surrey, Charlie stopped at around 62-6300 although the line was just starting to level out. It hadnt dropped at all yet although torque peaked around 5500rpm.
The last 383 went to about 7300, although usually shifted around 6800.
This 403 will go to 7k, but its a little lazier. So generally shift around 6500-6800 now.
just depends really.
Lookin at the graph from Surrey, Charlie stopped at around 62-6300 although the line was just starting to level out. It hadnt dropped at all yet although torque peaked around 5500rpm.
stevieturbo said:
More likely camshaft ?
Funny you should say that! Its in the process of being replaced. I tend to think it might not be helping either. My supposition is lack of exhaust duration. I have ported the throttle body since then, will see what happens with the new cam soon hopefully.But MAP pressure was ony 96kpa on the dyno so I was down about 5% air pressure anyway.
Ive gone for the combo approach.
ringram said:
stevieturbo said:
More likely camshaft ?
Funny you should say that! Its in the process of being replaced. I tend to think it might not be helping either. My supposition is lack of exhaust duration. I have ported the throttle body since then, will see what happens with the new cam soon hopefully.But MAP pressure was ony 96kpa on the dyno so I was down about 5% air pressure anyway.
Ive gone for the combo approach.
That and emissions dont usually go hand in hand though.
I would like more in the upper rpm's myself, but I'm not prepared to risk a camshaft that might be worse than I have.
My idle isnt bad...but I'd rather it was super smooth. Although I'd also like a good strong 7500rpm ability lol
maybe I need one of those Modular 32v Ford engines !
Yeah, I didnt really go any bigger.. well slightly smaller intake and bigger on exhaust, though some more overlap too. Idle will be a tad more lively. TBH its got enough power anyway. I could go silly, but then it would be bad to drive. I had it crawling at idle in 1st on the level and sligth incline ok. No jerking etc. We will see what the new one does.
I might just have to accept a lower useable rpm limit. Reliability is the main goal now!
Mine is a daily driver remember. Though yours looks fairly well driven too Stevie.
I might just have to accept a lower useable rpm limit. Reliability is the main goal now!
Mine is a daily driver remember. Though yours looks fairly well driven too Stevie.
Dont get me wrong.
Mine idles at circa 8-850rpm and the idle is rock solid. It just isnt smooth.
It also does drive without any problems.
Coming from always having turbo cars where you can make as much power as you like, with mild super smooth cams....I'd still love to retain that super smooth idle.
My only real option I think to achieve the same with a blower...is to use a bigger blower !!
But overall I'm more than happy with mine. It idles well, drives fine, and apart from when I do silly things, is pretty much totally reliable.
Mine idles at circa 8-850rpm and the idle is rock solid. It just isnt smooth.
It also does drive without any problems.
Coming from always having turbo cars where you can make as much power as you like, with mild super smooth cams....I'd still love to retain that super smooth idle.
My only real option I think to achieve the same with a blower...is to use a bigger blower !!
But overall I'm more than happy with mine. It idles well, drives fine, and apart from when I do silly things, is pretty much totally reliable.
with big cams the idle is not always the problem its more the "shunt" that is the problem normally around 1600-2000 rpm on no or very little throttle,i ran a 4,125" crank and ran it to 7200rpm with a 252-260 cam and idle was good but the emissions were grim, what you doing now with the motor richard ? going to be at the dyno day ?
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