[BFix] replacing 170 with a 200? 4.0??

[ts]

Yes and no. It does matter how hard that engine is working. The harder that you work an engine the shorter it's life will be, but also the less likely that it is operating at it's best rpm (unless on a governor).

Say it takes 35HP to move down the road at 65 mph. A 40 HP engine is going to be basically WOT for the duration, where a 100 hp engine will be running with higher manifold vacuum and at a leaner mixture than the 40 HP could stand.

Effective total gearing is huge. For best efficiency the engine needs to be operated at it's best Brake Specific Fuel Consumption rpm (BSFC, least fuel for most power produced), which happens to be the same rpm where peak torque occurs. 

Stephen Urban <sfu at roadrunner.com> wrote: As long as the engine has sufficient power to move the vehicle without 
struggling, mpg would be affected much more by other factors then what 
engine is in place. Explorer with hwy gears, 5-speed and street tires 
will obviously get better mpg then an EB with trail gears, 3-speed and 
mud terrains, even with the same engine.

Also are these posted mpg results for a 4x4 or 4x2 version of the Explorer.

Steve Urban
Semper Fi!
SCB#143
EBR#0692
CA4WDC#3576
NRA & CRPA Life Member
29 Palms, CA
sfu at roadrunner.com

Roger wrote:
>
> I average 17 driving to work. Mostly freeway but some weekend stop and 
> go. Maybe a tune up or some Lucas injector cleaner?
>
> *From:* bfix-bounces at broncofix.com [mailto:bfix-bounces at broncofix.com] 
> *On Behalf Of *Quinn Dusenberry
> *Sent:* Friday, May 02, 2008 9:19 AM
> *To:* 'BFix'
> *Subject:* RE: [BFix] replacing 170 with a 200? 4.0??
>
> I don’t think it would be much more economical the a 5.0L. My 97 
> Explorer with a 4.0L got just over 14 mpg on a recent freeway trip. 
> Pretty disappointing.
>
> ------------------------------------------------------------------------
>
> *From:* bfix-bounces at broncofix.com [mailto:bfix-bounces at broncofix.com] 
> *On Behalf Of *robert goodrich
> *Sent:* Friday, May 02, 2008 6:27 AM
> *To:* TJ Essenmacher; BFix
> *Subject:* [BFix] replacing 170 with a 200? 4.0??
>
> why not go 4.0 explorer motor? I heard it's the SBF bolt pattern so it 
> should be the same as a 5.0 conversion but a lot lighter and a lot 
> more economical! I thought of it before I built the 302!
>
> ------------------------------------------------------------------------
>
> From: tessen at btc-bci.com
> To: mail at broncofix.com
> Date: Fri, 25 Apr 2008 11:39:16 -0500
> CC:
> Subject: [BFix] replacing 170 with a 200?
>
> I have been told that a 200 is a decent improvement from the 170. I 
> have the opportunity to buy one cheap, my question is was will it take 
> to convert? the 200 is an auto ant the 170 is 3spd. I'm stil gathering 
> parts for the 351 upgrade but if this is quik and cheap enough it'll 
> work until my daughter gets out of college.
>
> Thanks,
>
> Tim
>
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