Quote:
Originally Posted by byndbad914
sounds cool... specs didn't list the rod but it must be pretty short like 6"? Assuming a deck to 9.235" that would leave a 1.185" CH in the piston...
I am not a big fan of really low rod to stroke ratios and a 6" rod on a 4.100" stroke is a 1.46 rod/stroke ratio, which is rather low but nothing completely out of the ordinary (454 BBC are low like that as well). Keep in mind a 347 Ford stroker is typically 1.59 R/S for example.
For a street rod no big deal, just for a guy like me that will maintain them in the 5K-7K rpm band for extended periods on road courses, it is a bit rough on bearings and low compression height pistons to run such a low R/S IMHO. I prefer 1.6 minimum for sustained rpm with V8s of 5K-8K, so if you are considering sustained rpm with your project (don't know cuz it is "secret" and I appreciate that, my next project is secret as well) I would take that into account.
edit - and I state this fully aware of the LS7 having a short tho' higher 1.5 R/S and similar CH... I am just not a fan personally as I have seen engines with those low R/S values knock pistons out of them in race applications and show aggressive bearing wear.
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Byndbad914:
Thanks for the response and information.
I have some information regarding the above numbers for accuracy.
I asked some specific questions and I was sent this:
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The connecting rod length is 6.125" which creates a R/S ratio of 1.5. We do not have any concerns of bearing wear at extended RPM's for your application.
Also, We have implemented new piston technologies including ring packages and piston coatings that improve ring seal and wear.
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As you have mentioned the LS7 also has a 1.5 R/S Ratio, this engine appears to be inline with that. I'm not sure what the average Ratio is for the LS Engine platforms, but this one is limited @ 7000 rpm, and they have done research with this particular package running for extended periods of time at high rpms.
I wanted something that would be strong enough to have a lot of fun with, and take it to the track as often as possible, and be able to run the Power Tour easily. Based on the parts that come in the engine, and their attention to detail, this looked like a nice package. Plus, for everything that comes with it a good bang for the buck.
I'm wondering if there is a substantive difference in the acceptable R/S Ratio between the Gen IV and the SBC's?
I am currently running a 400 SBC with 550 hp in my Camaro, and this LS3 427 running with the SS (Hotter) Cam rather than the regular HO Cam, will put out a good 50+ hp more than my SBC, but it idles with a nice lope at 650-700 rpm and 13+ pounds of Vaccuum, whereas my SBC Idles at 1100 rpm with 8-9 Pounds of Vaccuum.
I realize that there are 27 more cubes in the Gen IV Engine, but the manners are so very much different and the mileage one can expect with the LS3 is 3X's that of the 7 mpg of the SBC 400. The LSA in the 400 SBC is 108 degrees vs. 114 degrees in the LS3 427.
I think DSE just picked up one of their, "Race Prepped", LS3 416's. I'm sure they will be seeing a lot more events than I will, however the LS3 427 with a (Callies and Mahle) forged bottom end and ARP fasteners throughout, I'd be shocked if it wouldn't handle quite a bit of Thrashing and a nice kick in the seat to boot.
I am certainly open and interested in your knowledge of engines, and I hope you will give some more particulars of the SBC your running, and of course if you have some specific knowledge of what the big and small differences between the SBC and the GM Gen IV engines are, please educate me.
I look forward to your answers. (Hopefully)
Best Regards,
Ty O'Neal