LS motors are naturally pretty fuel efficient.. my HCI 08 Silverado did 19mpg from Massachusetts to Tampa FL last winter!! This year I’ll be taking my 03 z06 and expecting to do over 20mpg
I will say that I have built engines of equal displacement at different power levels and an engine built to optimize low end torque tends to be more fuel efficient. (My idea of a low end torque engine is as much compression as pump gas with accommodate, a mild camshaft, and decent flowing heads. Make the engine more efficient at the desired peak torque range.) My theory is that in a street driven vehicle, more torque equates to less throttle to accomplish the same amount of work under normal driving conditions. Highway mileage is better as well. As an interesting side note. Several members of my family owned mid 70s 302 powered F100s & F150s. My father purchased a ‘76 F150 with a 360 and everyone was shocked when it got better fuel economy than any of the 302 powered trucks. I felt that the added torque was a factor. Strangely enough, I swapped stock 350TPI in place of a stock 305 TPI and the highway fuel economy was exactly the same.
There a couple things you don't hit on . The Wright question. How much tork do you need at a given rpm . Next the engine uses Hp to move air fuel exhaust in and out. This is where lobe pattern is significant and duel pattern cams are of interest . Look at your cam grinders book of patterns! All Wright Holder it's all yours and by the way you do a great job !
Not sure if you mean torque at WOT? torque at part throttle? Hp is used to move air, fuel and exhaust in and out? Also, Lobe patterns don't tell us what the dyno tells us about whether the cam works or not
Other than 6cu in of displacement and part availability, are there other downsides to running a .010 over stroked setup as opposed to a .030 over stroked setup on ported 243s? I’d like to think the extra .020 on the cylinder wall adds strength and gives more leeway to the 402 block for future bore honing. Just trying to get an idea of any drawbacks 402 vs 408 and map out my build. As always keep it up Richard great vids!
Friction generally goes up with rpm so the lower the rpm usually the better the fuel economy. The caveat is of course that the power required to maintain speed is considerably less typically than an engine can make so that has a big effect on efficency. More displacement almost always burns more fuel to do the same work.
The engine should reach peak efficiency at the peak torque. That doesn’t necessarily mean that the best fuel economy will be at peak torque. Airflow & rpm’s have to factored in. When you have more throttle and higher rpm’s, an engine requires more fuel. Something worth mentioning is that on newer cars, overdrive transmissions had a greater impact on fuel economy than fuel injection. Reducing the rpm’s at highway speed improved fuel economy.
hay love the show i have been Learning a lot with you It seems like the more hyperformance I go the better fuel knowledge went from a stock 350 made it into a 383 stroker then built a 406 out of a small box 400 with supercharger what a big difference in those engines best fuel knowledge 383 super charged 262 comp cam in both Smart blocks Fuel mileage went from 10 miles to the gallon to 21😂 I spent more money on parks than I would have if i'd just paid in gas ha ha
I know it's not a 408, but how about that LY6 you have access to? That engine with the stock rec port top end. Then an LQ4/LQ9 cam, the TN or one of the others in that range/design. The Crane 224/232 if you still have access to it, maybe the Sloppy Best, and the Crane 206 if you still have it. Smaller displacement, but still bigger than the most common 5.3L and high high flow heads on the LY6 with big valves. I'd even like to see a set of 706s with the FAST LSXRT thrown into that mix. Would be interesting to see the curves of all of those. I feel like you've tested a few of those combos already, which would save time somewhat as far as data collection. In the 408 test, I really like the 224/232 combination. It barely lost anything down low, and made considerably more above 5000 RPM. Seems like the best overall for a heavy truck or SUV.
A relationship between torque and mileage, yes. Just cruising at peek torque alone will not provide the best mileage. If peak torque is over about 2500 RPM rotational and friction loss become a much bigger factor in fuel economy. If the engine in question makes enough power to maintain the desired speed at lower rotational speed an overdrive or appropriate gearing will provide better economy. On peak torque at 2000 RPM, you forgot the 400 Ford which often reached peak torque at 1800 RPM and carried it practically flat to 3000 or so.
Richard, I'm working on a 408 build 2011 6.0 with the stock intake and 823 heads. Would the btr truck norris have good to great bottom end torque for one tons and 40inch tores
hi Richard, I've been enjoying your show very much and was wondering what your thoughts were on the size of the Cleveland big ends, I always thought they were nearly to big and this made it difficult to maintain a good oil film , which is why they go well as a stroke, when you offset grind you come back a bit on journal size and cured any oil churning in the big ends, lower surface speed and better longevity
Ifeel like we would be using the most fuel from peak torque to peak HP so the fuel mileage would be bad or the engine would suck I Stroked mine so i could go use more cam and have both.
Hey Rich, I'm building a 402 stroker for a turbo application (hopefully around 1000hp) and I'm looking for good grunt at low rpm. My question is: will making more low speed torque help the turbo spool faster? I just want to help it reach peak boost as quickly as possible. Watching your videos I'm considering 862/706 heads, tbss manifold, and maybe the Truck Norris cam. Is my assumption correct for this setup?
@@richardholdener1727 follow up question, would the increased displacement work better with the 862/706 small valve heads or is it worth the money to go for a smaller volume aftermarket head? I noticed you didn't recommend the 245~ heads for your stroker application and am curious what cathedral port head you'd choose for my application
I’m wanting to build a motor for my tow rig excursion 32’ enclosed currently 5.4 2v gas and gets 5.33 mpg. I have built a lot of ls motors. Like the 4l80 trans. But want fuel mileage and towing torque not peak hp. Trying to decide between 5.3 with a 4” stroke or a 6.0 with 4” stroke and 799 heads I’m open to turbo and have tuned a lot of turbo ls stuff. I would love 15 mpg empty 11 loaded at 65 mph but unsure how to get there. Also have a k24 with a gm adapter plate wouldn’t be against that with a turbo to get fuel mileage and pull the trailer sufficiently 500ftlb 600 ft lb goal 2500-3700rpm
Ok, so I just purchased a atk 408 stroker with 68cc heads it says the compression ratio is 10.7:1. I’m just running stock 243s with a 85mm turbo on e85. Is that to much of a Compression ratio for that kinda setup?
For my ls 408 root supercharger build, would a 226/25x .636”/.636” 112.5 Lsa can be too aggressive to drive regularly on? As far as idle choppiness and just daily drivability…just want to be able to unleash high hp when desired but still have a solid reliable strong daily drivable motor as well. The specs are the btr stage 3 Pds v2 cam for reference, I feel the stage 4 might be the cam that is too aggressive for my desires
@@richardholdener1727 is there a “happy number” to stay under when it comes to cam overlap? Just went to the summit calc and even at 250 duration (25x), it’s 13 degrees overlap. Don’t want low engine vacuum or a bad/rough idle due to too much overlap at low rpms (I think I’m learning LoL) thanks!
@@pbadasay 220-225 intake duration on 115lsa would have great low rpm tq and driving manners in a 408...... That one has way to much exhaust duration
Hey Richard, could you recommend a cam for my LS1 Holden adventra ? It’s a 5.7, has the LS6 intake with 241 heads, in a heavy all wheel drive combo with a 4l60e and 3:45 gears. I’d like more power and economy, thanks
Well if a 408 would be a fun daily i wonder how a 427 or 454 aftermarket engine would do in my 2500 gmc... 🤔 Why stop there right. Lets see if i can talk the wife into it and see if I can add a supercharger just for more fun. I've never been a fan of has mileage anyways. Lol
In the Mobilgas economy run we got the best mileage with the tallest gear and the widest throttle opening i.e 3 ish gears were better than 3:31 which was the tallest on the order sheet with the 3 sp w/ od trans Nash Rambler Flathead note the low 2s in late GM like 2:29
Thanks for all yhe great videos, I'm replacing a grenaded 6.2 in an Escalade, going to replace it with a 6.0, just wanting to do a little better than the 400hp of the stock 6.2, up to maybe 450-500hp, really just want daily drivability more than hot rod, can you recommend cam and heads, thinking nice aftermarket heads and truck Norris cam, was going to stroke it to 408 since tourque will be better than hp but worried about mpg and piston wear longevity, this conversation has me back thinking about a low rpm stroker again I rarely ever go over 3500 rpm, any imput is greatly appreciated, thank you!
@@richardholdener1727 in that case, what cam would be better for dd/occasional towing in a 2500hd with 4:10s and 33” tires. Assuming it’s a 402ci and has factory intake, TB, and heads (or even 706 for higher CR).
On gas mileage. I had a friend that went from a v6 Ranger to v8 f150 and said was getting much better gas mileage. Now I'm starting to wonder if its true that all fat girls are really sweet 🤔
