Hp and MPG?

Poodles

I play with fire
Jul 22, 2006
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Honestly, it only uses as much throttle as necessary. On a stock car it wouldn't boost at those times, but of course who's stock anymore? :rofl:
 

Canuckrz

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Jan 13, 2009
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I'd have to argue that point, back when my car was bone stock it would break into boost with cruise control all the time on the highway with any kind of slope. Like I said previously its throttle adjustments seemed pretty abrupt.

Therefore limiting the ammount of pressure the engine can produce under cruise (even if you're still below the stock gauge's vacuum still) could theoretically give much better gas milage. That being said a steady right foot would likely still yeild the best results.

Also theoretically good synthetic oil in your transmission and diff could yeild a minor milage increase, or atleast this what seems to be reported on some of the hypermiler websites. I had done too much else the car in conjunction with my car to say if any of the results I had were related to the synthetic gear oil or not.
 

Dan_Gyoba

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Aug 9, 2007
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Canuckrz;1769465 said:
So if the cruise is vacuum operated, could you theoretically if install a MBC or similar in the line thereby limiting the throttle the cruise uses to not go past whatever you choose to set it at?
Nope. It wouldn't work that way. Instead, it would not applhy ANY throttle at all, until it got tot he point where it hit the controller threshhold, then it would pin it (Up to almost zero manifold pressure) until it got back up to speed.

I know that the car will go into boost bone stock, but since bone stock boost is relatively low, this really isn't quite the same.

You could make a cable adjustment for the cruise, so that it can't put the throttle in as far. This would have the effect of limiting the max throttle that the cruise could pull, and probably be adequate to limit it. Some trial-and-error would be needed to ensure that you can still get enough throttle to maintain speed, without MORE than is needed.
 

Nick M

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Sep 9, 2005
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I prefer rolling into boost with cruise when climbing a hill over a down shift. Leaving in normal and not sport really limits the downshifts on hills.
 

Poodles

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Jul 22, 2006
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Canuckrz;1769552 said:
I'd have to argue that point, back when my car was bone stock it would break into boost with cruise control all the time on the highway with any kind of slope. Like I said previously its throttle adjustments seemed pretty abrupt.

Therefore limiting the ammount of pressure the engine can produce under cruise (even if you're still below the stock gauge's vacuum still) could theoretically give much better gas milage. That being said a steady right foot would likely still yeild the best results.

Also theoretically good synthetic oil in your transmission and diff could yeild a minor milage increase, or atleast this what seems to be reported on some of the hypermiler websites. I had done too much else the car in conjunction with my car to say if any of the results I had were related to the synthetic gear oil or not.

Mine was abrupt until I adjusted the assembly and removed the slack. A steady foot couldn't do any better, unless of course you slow down going up hills.

Good oils definately improve milage. So do thinner oils. The RX-8 runs 5w-20 in the US to achieve standards set by the EPA. Of course the rest of the world they run thicker oil and the engines last longer as it was designed for 5w-30.
 

te72

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Nick M;1769576 said:
I prefer rolling into boost with cruise when climbing a hill over a down shift. Leaving in normal and not sport really limits the downshifts on hills.
At least on my NA auto, I seemed to get better mileage with the trans set on sport. However, this was 90% in town driving, talking a lot of low speed 30-40mph stuff.

Poodles;1769592 said:
Good oils definately improve milage. So do thinner oils. The RX-8 runs 5w-20 in the US to achieve standards set by the EPA. Of course the rest of the world they run thicker oil and the engines last longer as it was designed for 5w-30.

That's an easy enough fix for the RX8 guys. :)
 

Bleakvoid

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Oct 7, 2010
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Poodles;1769592 said:
Mine was abrupt until I adjusted the assembly and removed the slack. A steady foot couldn't do any better, unless of course you slow down going up hills.

Good oils definately improve milage. So do thinner oils. The RX-8 runs 5w-20 in the US to achieve standards set by the EPA. Of course the rest of the world they run thicker oil and the engines last longer as it was designed for 5w-30.

Funny you mention the RX8...I just learned that they do not like the 2-stroke treatment that the older 13B motors need to stay alive. Every month, my friend would put a $0.99 bottle of 2-stroke oil in the gas tank of his FC. Put 240k miles on the original apex seals, and it died with 280k on the clock. Sold it, bought the RX8, turboed it, and blew the Renesis after 70k this week.

/OT

I'm all for cruise control on flat highways, but I find I get much better mileage up and down hills with my own throttle control...key is to speed up a little going down and slow down a bit going up. Unless you're in a turbo car, in which case boost the hell on up there...it's what that snail under the hood is for ;)
 

Nick M

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te72;1769620 said:
At least on my NA auto, I seemed to get better mileage with the trans set on sport. However, this was 90% in town driving, talking a lot of low speed 30-40mph stuff.

Yep. You are not loading the engine as much with the lower gearing. As long as you aren't on the loud pedal as hard and the rpm isn't held up real high for long stretches, city milage goes up. Mine went up when I went from the 3.08 to a 3.73 in my 5.0
 

Crypton2006

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Jun 26, 2006
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I really dont see how you guys do a hundred mile trip without getting into boost..lol I get between 16-18mpg at 490whp R154 and a 4.30... I have had this car 7 years and i still cannot contain myself when im driving it. Its more about the symphony of amazing sounds then the accelaration. My friends and I often joke that Crack would be a cheaper addiction.
 

te72

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Crypton2006;1770824 said:
My friends and I often joke that Crack would be a cheaper addiction.

Dave Attel made a similar joke about cigarettes in NYC once. The price of gasoline these days, I can see that...
 

STREET90

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Jan 8, 2011
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Is getting 17-18mpg normal 260 miles per tank
mx83 cressida same weight as a supra
7mgte stock only 6000 miles on it with intake, 2.5 intercooling, big intercooler, 3" exhaust but 2in downpipe :( w58 trans, 3.91 final gear, and 215/60/15 tires
 

te72

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STREET90;1772232 said:
Is getting 17-18mpg normal 260 miles per tank
mx83 cressida same weight as a supra
7mgte stock only 6000 miles on it with intake, 2.5 intercooling, big intercooler, 3" exhaust but 2in downpipe :( w58 trans, 3.91 final gear, and 215/60/15 tires

All depends on how you drive really. Mostly highway, yes that's pretty crappy mileage. If it's mostly low speed, in town stop and go kind of driving, it's not horrible. Not great, but not horrible either.
 

Nick M

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Crypton2006;1770824 said:
I really dont see how you guys do a hundred mile trip without getting into boost

Why do I need to go into boost?

[video=youtube;rTS6GjHy81k]http://www.youtube.com/watch?v=rTS6GjHy81k[/video]

..lol I get between 16-18mpg at 490whp R154 and a 4.30...

I am not suprised. Your engine speed at 70 mph is probably close to 3000 rpm. It isn't about having fun, I get that milage on road trips. Not in the daily commute.
 

barkz

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Crypton2006;1770824 said:
My friends and I often joke that Crack would be a cheaper addiction.

lol check out my avatar "BOOST, and u thought crack was addicting" made it on a "make-your-own" motovational poster sites lol
 

Crypton2006

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Jun 26, 2006
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Nick M;1772490 said:
Why do I need to go into boost?


I am not suprised. Your engine speed at 70 mph is probably close to 3000 rpm. It isn't about having fun, I get that milage on road trips. Not in the daily commute.

I think you misunderstood, I ment that i have a hard time going a long distance with out intentionally getting into boost. Believe me i have a 67mm and i have to REALLY want to boost or the big grumpy snail inst going to wake up..lol
 

te72

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Crypton2006;1773388 said:
I think you misunderstood, I ment that i have a hard time going a long distance with out intentionally getting into boost. Believe me i have a 67mm and i have to REALLY want to boost or the big grumpy snail inst going to wake up..lol

You also live in the part of AZ that has hills and mountains... I'm sure a 67mm doesn't behave like the twins on mine, but mine go into boost just because of the load on the engine from the hills around here.
 

destrux

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May 19, 2010
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With my HY35 I stay in vacuum going up mountains as long as I keep it below 3000rpm in 5th or go a gear down to bring the RPM up to where the engine has enough HP that it doesn't need boost. It was easier with the HX35, more lag, but then I HAD to keep it a gear down if I was doing less than 60mph or I would start slowing down on the steep hill. 1JZ's have no power or torque without boost.