j4nash Posted August 7, 2005 Report Share Posted August 7, 2005 well if those dyno numbers look good zippy i think i might just go for the 408 like you were thrying to get me to do Link to comment Share on other sites More sharing options...
zippy Posted August 7, 2005 Author Report Share Posted August 7, 2005 Choices... Link to comment Share on other sites More sharing options...
misterp Posted August 8, 2005 Report Share Posted August 8, 2005 So what is it that determines the mileage on one of these motors? Cam + heads + intake? Stroking a LS2/LQ9 to a 408 is kind of a special beast, especially when you use stock-length rods. You lower the rod/stroke ratio a whole 10% (from 1.68 to 1.53) and this means that this particular configuration of 408 breathes very differently because the piston dwells some 8 crank degrees longer at BDC then it used to; the only other engine that has a R/S ratio that low is the 454 BBC. The phasing of the cam matters as well, at what points the valve events are occuring in relation to piston position in the bore. Also, stroking an engine typically lowers the RPM at which peak torque occurs (all else equal) so maybe on the freeway it shows a better bsfc at 2000-2500 rpm? Zippy - I am really interested in your cam swap findings, especially torque curve and peak. Link to comment Share on other sites More sharing options...
misterp Posted August 8, 2005 Report Share Posted August 8, 2005 11.7 on pump gas? Pretty high. Sounds like it would be very sensitive to timing changes. But, I know some have gone 12+. Depends on where the intake valve closing event is; I'd guess if the cam was installed with the IVC > 46-degrees ABDC it'll bleed off enough cylinder pressure... mwalls54 - would you be willing to share a scan of that cam card? Mr. P. Link to comment Share on other sites More sharing options...
zippy Posted August 8, 2005 Author Report Share Posted August 8, 2005 if all goes well i'd like to have dyno numbers of the truck in it's current mechanical condition with some tuning time and dyno numbers after the cam and head swap. in it's current state i'd be pretty impressed if it were to put down 400 to the tires. Link to comment Share on other sites More sharing options...
mwalls54 Posted August 8, 2005 Report Share Posted August 8, 2005 the cam card is a little over 4000 miles away from me right now and wont be able to get it untill probably next year. but off the top of my head its in the 220 and 540 range with 114 lsa Link to comment Share on other sites More sharing options...
TBSS Posted August 8, 2005 Report Share Posted August 8, 2005 So what is it that determines the mileage on one of these motors? Cam + heads + intake? Stroking a LS2/LQ9 to a 408 is kind of a special beast, especially when you use stock-length rods. You lower the rod/stroke ratio a whole 10% (from 1.68 to 1.53) and this means that this particular configuration of 408 breathes very differently because the piston dwells some 8 crank degrees longer at BDC then it used to; the only other engine that has a R/S ratio that low is the 454 BBC. The phasing of the cam matters as well, at what points the valve events are occuring in relation to piston position in the bore. Also, stroking an engine typically lowers the RPM at which peak torque occurs (all else equal) so maybe on the freeway it shows a better bsfc at 2000-2500 rpm? <{POST_SNAPBACK}> Link to comment Share on other sites More sharing options...
misterp Posted August 8, 2005 Report Share Posted August 8, 2005 It draws more vacuum! Mr. P. Link to comment Share on other sites More sharing options...
misterp Posted August 8, 2005 Report Share Posted August 8, 2005 the cam card is a little over 4000 miles away from me right now and wont be able to get it untill probably next year. but off the top of my head its in the 220 and 540 range with 114 lsa What brand of cam? Link to comment Share on other sites More sharing options...
big hack Posted August 8, 2005 Report Share Posted August 8, 2005 Choices... <{POST_SNAPBACK}> I like the SS on the left.. your left..the one with the Virginia tags Link to comment Share on other sites More sharing options...
haynss Posted August 8, 2005 Report Share Posted August 8, 2005 matt hows about a FMS 228/224 .575/.576 115+4 cam gas mileage sucks ass!!! 8.1 on last 2 tanks Link to comment Share on other sites More sharing options...
j4nash Posted August 8, 2005 Report Share Posted August 8, 2005 that is bad, if i do the build i would like to get at least 17 on the highway Link to comment Share on other sites More sharing options...
zippy Posted August 8, 2005 Author Report Share Posted August 8, 2005 after having driven this one as much as i did i'd have to say it's possible. it's going to be a bit before i can get it dyno'd. i have to wait until i can get the time off and get it scheduled for a dyno run. the closest awd dyno is about 200 miles away. Link to comment Share on other sites More sharing options...
BigTex Posted August 8, 2005 Report Share Posted August 8, 2005 I think the CR as it sits right now is more like 10.75:1 going on the assumption that stock GM MLS head gaskets were used and the heads haven't been milled. Link to comment Share on other sites More sharing options...
zippy Posted August 8, 2005 Author Report Share Posted August 8, 2005 I think the CR as it sits right now is more like 10.75:1 going on the assumption that stock GM MLS head gaskets were used and the heads haven't been milled. cool, good to know. Link to comment Share on other sites More sharing options...
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