Go Back   Ford Truck Enthusiasts Forums > Performance, Engines & Troubleshooting > Small Block V8 (221, 260, 289, 5.0/302, 5.8/351W)
Sign in using an external account
Register Forgot Password?


Reply
 
 
 
 
LinkBack Thread Tools Search this Thread
  #1  
Old 08-03-2010, 01:40 PM
rogersdan rogersdan is offline
Junior User
 
Join Date: May 2002
Posts: 60
rogersdan is starting off with a positive reputation.
5.8L Engine specs (HP,Torque,RPM's)

I have a 1988 F250 with the 5.8L. Had some power (lack of power) issues and the mechanic said that the 5.8L had to operate at higher RPM's to maintain maximum HP. Anyone know the maximum HP and corresponding RPM's for this engine?

Thanks, DR
Reply With Quote
  #2  
Old 08-03-2010, 01:59 PM
85e150six4mtod 85e150six4mtod is offline
Post Fiend
 
Join Date: Apr 2004
Posts: 16,238
85e150six4mtod has a superb reputation85e150six4mtod has a superb reputation85e150six4mtod has a superb reputation85e150six4mtod has a superb reputation85e150six4mtod has a superb reputation85e150six4mtod has a superb reputation85e150six4mtod has a superb reputation85e150six4mtod has a superb reputation85e150six4mtod has a superb reputation85e150six4mtod has a superb reputation85e150six4mtod has a superb reputation
Higher RPMs compared to what? You trying to pull OD at 1200 rpm or something?

Specs for '88 included here, no guarantee these are accurate, but they look right:

Engine_Specifications


A MPFI 5.8 shows 210 hp at 3800, 315 ft/lb at 2800.

HP and TQ peaks at higher rpm than the 300 six, but with more of both. If you had a dyno readout you'd probably see the 351 makes about the same or more HP and torque at those lower revs than the 300 does. (you think it gains 60 hp in 400 rpms, for example, or that it gains 55 ft/lb in 800 rpms?)

Compared to a 460, the peaks are 3600 for 230 HP, and 2000 for the 390 ft/lbs torque, so yes, the 460 is going to have LOTS more low end than a 351w, but you'd expect that.

2800 is hardly "high rpms" for a gas engine. 3800 probably sounds high, but you still have 290 ft/lbs of torque at those revs, so it should pull nicely from 2000 rpms up, and depending on your transmission ratios, you could probably run it between 2400 to 3400.

That's not to say that the 351w is powerful enough for your application, maybe you need more motor.
Reply With Quote
  #3  
Old 08-03-2010, 02:17 PM
rogersdan rogersdan is offline
Junior User
 
Join Date: May 2002
Posts: 60
rogersdan is starting off with a positive reputation.
Thanks for the information and the link and your right "higher RPM's compared to what"?

I have an F250 with a 1500lb camper on the back and had some trouble maintaining a reasonable speed (dropped to under 45mph) over some long big hills in Montana. Have had the truck tuned, the catalytic converter checked for restrictions, the transmission (C6) checked with marginal improvements.

The mechanic said that I need to maintain the RPM's so that the truck stays in the power band - but it sure seems like it is working real hard to maintain get over the hills.

Otherwise runs great!

Thanks again, DR
Reply With Quote
  #4  
Old 08-03-2010, 06:05 PM
Conanski's Avatar
Conanski Conanski is offline
Post Fiend
 
Join Date: Jun 2006
Location: Ottawa, Ontario
Posts: 20,724
Conanski has much to be proud ofConanski has much to be proud ofConanski has much to be proud ofConanski has much to be proud ofConanski has much to be proud ofConanski has much to be proud ofConanski has much to be proud ofConanski has much to be proud ofConanski has much to be proud of
The stock exhaust is a cork on these trucks.. even with a non clogged cat.
__________________
Paul (Conan) O'Brien

1990 5.0HO AOD XLT X-Cab F150 3.55LS, 1994 3.0L 5-sp x-cab Ranger 3.45, 2004 3.0L 5-sp X-cab Ranger Edge 4.10, 2004 2.5L 5-spd Subaru Legacy
1996 Kawasaki ZX11D, 2004 Honda 599, 2008 Kawasaki KLR650
Reply With Quote
  #5  
Old 08-03-2010, 09:05 PM
rogersdan rogersdan is offline
Junior User
 
Join Date: May 2002
Posts: 60
rogersdan is starting off with a positive reputation.
If the stock muffler is a cork; do you have any recommendations for a replacement?

Thanks, DR
Reply With Quote
  #6  
Old 08-03-2010, 09:51 PM
Conanski's Avatar
Conanski Conanski is offline
Post Fiend
 
Join Date: Jun 2006
Location: Ottawa, Ontario
Posts: 20,724
Conanski has much to be proud ofConanski has much to be proud ofConanski has much to be proud ofConanski has much to be proud ofConanski has much to be proud ofConanski has much to be proud ofConanski has much to be proud ofConanski has much to be proud ofConanski has much to be proud of
Any performance muffler will be an improvement but I like the flowthrough designs like those from magnaflow, and not to worry it won't be loud with the stock cats in place.
__________________
Paul (Conan) O'Brien

1990 5.0HO AOD XLT X-Cab F150 3.55LS, 1994 3.0L 5-sp x-cab Ranger 3.45, 2004 3.0L 5-sp X-cab Ranger Edge 4.10, 2004 2.5L 5-spd Subaru Legacy
1996 Kawasaki ZX11D, 2004 Honda 599, 2008 Kawasaki KLR650
Reply With Quote
  #7  
Old 10-05-2010, 08:27 PM
ford5.8's Avatar
ford5.8 ford5.8 is offline
Elder User
 
Join Date: Apr 2003
Location: ND
Posts: 664
ford5.8 is starting off with a positive reputation.
You could even take the muffler off completely and it still wont be noisy. That cats quiet it down ALOT.
Reply With Quote
  #8  
Old 10-05-2010, 10:19 PM
Conanski's Avatar
Conanski Conanski is offline
Post Fiend
 
Join Date: Jun 2006
Location: Ottawa, Ontario
Posts: 20,724
Conanski has much to be proud ofConanski has much to be proud ofConanski has much to be proud ofConanski has much to be proud ofConanski has much to be proud ofConanski has much to be proud ofConanski has much to be proud ofConanski has much to be proud ofConanski has much to be proud of
These early EFI motors are smothered badly, as already pointed out the exhaust is restrictive but the cam is also rediculously small. That wouldn't be too bad but the motor is also wearing heads that were designed for a 289 so all combined it's operating FAR below it's potential. The single best thing you can do to help this motor is change the cam, heads swaps are good but for $229 the Crane 444232 simply outguns all other mods on the bang for you buck scale, combine it with an exhaust system and you'll have a truck that performs the way it should have from the factory. And the best thing is it'll behave just as well as it does not, smooth idle, no codes, just lots more power.
__________________
Paul (Conan) O'Brien

1990 5.0HO AOD XLT X-Cab F150 3.55LS, 1994 3.0L 5-sp x-cab Ranger 3.45, 2004 3.0L 5-sp X-cab Ranger Edge 4.10, 2004 2.5L 5-spd Subaru Legacy
1996 Kawasaki ZX11D, 2004 Honda 599, 2008 Kawasaki KLR650
Reply With Quote
  #9  
Old 10-06-2010, 01:43 PM
Beanscoot Beanscoot is offline
Posting Guru
 
Join Date: May 2007
Location: British Columbia
Posts: 1,509
Beanscoot is gaining momentum as a positive member of FTE.Beanscoot is gaining momentum as a positive member of FTE.
Engine powering out

I would install a tachometer in the truck if it doesn't have one. You will probably be surprised that 3500 rpm seems awfully fast if you've been driving conservatively, without a tach.

The motor will have to work awful hard to move a heavy truck and camper up long grades, but if you keep it in the 3000-3500 rpm range it should be fine at WOT for the duration. A 351W in a boat will do that for hours on end.

Oh, you don't need one of those 8000 or 10,000 rpm ones. A good old Sun 6000 rpm tach is quite sufficient, and cheap at swap meets because most people are unrealistic about the engine speeds they will be running.

Do you have an automatic or manual transmission?
Reply With Quote
  #10  
Old 10-06-2010, 09:11 PM
rogersdan rogersdan is offline
Junior User
 
Join Date: May 2002
Posts: 60
rogersdan is starting off with a positive reputation.
I have a 3 speed C6.

Thanks for the suggestions, I'll try the exhaust modifications first and if that gets me up the hills, I'll be satisfied. I don't know about changing the cam - its not something I would tackle myself - more likely sell the truck and get something more suited for the task.

Thanks for the help. DR
Reply With Quote
  #11  
Old 10-17-2010, 08:11 AM
andyman7931's Avatar
andyman7931 andyman7931 is offline
Senior User
 
Join Date: Nov 2008
Location: Western NC
Posts: 113
andyman7931 is starting off with a positive reputation.
You may also want to look at what your final drive gears are like. I have the same setup as you and swapped in 3.73 gears before my 351 would pull weight on the highway. You may want a higher gear ratio if you have larger tires on your 250. From stock to a crane 444232 with 3.73 gears made my truck feel like a new torque monster. I aimed for 3000 rpm at 65 mph.
__________________
1989 F-150 XLT 4X4 351/c6 3.73 gears
Reply With Quote
  #12  
Old 10-17-2010, 11:54 AM
rogersdan rogersdan is offline
Junior User
 
Join Date: May 2002
Posts: 60
rogersdan is starting off with a positive reputation.
Thanks for the info. Don't know anything about gear ratio's. Can I tell the gear ratios from the VIN number? If not, how do I know what gear ratio is currently in the truck?

Thanks, DR
Reply With Quote
  #13  
Old 10-17-2010, 10:14 PM
Conanski's Avatar
Conanski Conanski is offline
Post Fiend
 
Join Date: Jun 2006
Location: Ottawa, Ontario
Posts: 20,724
Conanski has much to be proud ofConanski has much to be proud ofConanski has much to be proud ofConanski has much to be proud ofConanski has much to be proud ofConanski has much to be proud ofConanski has much to be proud ofConanski has much to be proud ofConanski has much to be proud of
The axle code on the drivers door pillar will give you the final drive ratio.
Ford Axle Code Chart .: Articles
__________________
Paul (Conan) O'Brien

1990 5.0HO AOD XLT X-Cab F150 3.55LS, 1994 3.0L 5-sp x-cab Ranger 3.45, 2004 3.0L 5-sp X-cab Ranger Edge 4.10, 2004 2.5L 5-spd Subaru Legacy
1996 Kawasaki ZX11D, 2004 Honda 599, 2008 Kawasaki KLR650
Reply With Quote
  #14  
Old 04-11-2011, 11:09 PM
TroySmith80 TroySmith80 is offline
New User
 
Join Date: Mar 2011
Posts: 5
TroySmith80 is starting off with a positive reputation.
Quote:
Originally Posted by Conanski View Post
These early EFI motors are smothered badly, as already pointed out the exhaust is restrictive but the cam is also rediculously small. That wouldn't be too bad but the motor is also wearing heads that were designed for a 289 so all combined it's operating FAR below it's potential. The single best thing you can do to help this motor is change the cam, heads swaps are good but for $229 the Crane 444232 simply outguns all other mods on the bang for you buck scale, combine it with an exhaust system and you'll have a truck that performs the way it should have from the factory. And the best thing is it'll behave just as well as it does not, smooth idle, no codes, just lots more power.
Great info here. Does this also apply to a 1992 E-350 with the 5.8 and an E40D? My van has been converted to 4WD, lifted 4" and has a 30" fiberglass top that allows me to stand up inside. I'm converting it into a camper (poor man's Sportsmobile) and i think it's going to need to be geared down a LOT. Right now I think it has 3.54 gearing according to the door tag. I also want to go up a little in tire size (30.5" now, 33" preferable). I don't have a tach, but currently in overdrive, it sounds like it's barely turning.

If my calculations are correct (big if!) right now it should be running around 1670RPM at 60mph in overdrive. And at 2,500 RPM in O.D. i would be going 90 mph. It's got hardly any power and is getting bad mileage too. The thing is so tall (probably 10 feet!) that i don't think i'll ever want to go much over 65 mph because the fuel consumption would be so bad. I'd like to gear it to be most efficient between 55-70 mph.

So if i went to 5.29 gearing in the diffs, that would yield 2390 RPM with a 33" tire at 62 mph. Does that seem right? It's a huge change in gearing so i'm concerned that i'm not doing the math correctly. According to the same math my current tires with 5.29 gearing would be 2580 RPM at 62 mph.

my rig:

Click the image to open in full size.
Reply With Quote
  #15  
Old 04-12-2011, 01:55 AM
Beanscoot Beanscoot is offline
Posting Guru
 
Join Date: May 2007
Location: British Columbia
Posts: 1,509
Beanscoot is gaining momentum as a positive member of FTE.Beanscoot is gaining momentum as a positive member of FTE.
RPM at 62 mph

Okay... I just checked your math and I get 2383 rpm with a 33" tire at 62 mph. How come you chose 62 mph for the rpm measurement with the 5.29 gearset vs. 60 mph for the original 3.54 ratio? It seems to add a little unnecessary confusion to the issue.

P.S. That beast doesn't look like it's going into the garage!
Reply With Quote
Old 04-12-2011, 01:55 AM
 
 
 
Reply

Similar Threads
Thread Thread Starter Forum Replies Last Post
Factory rated H.P for 5.8L in 95 Bronco XLT pwcharlie 1978 - 1996 Big Bronco 2 10-16-2006 05:57 PM
1991 5.8 Torque and HP specs ckchevyman26 1987 - 1996 F150 & Larger F-Series Trucks 2 08-18-2003 12:45 PM
Opinions on 5.8L engine mods. PA_Fordman 1997 - 2003 F150 2 01-14-2003 04:02 PM
1988 F250 V8 5.8L FI - Loses power over 3000RPM Help? Franklin2 Small Block V8 (221, 260, 289, 5.0/302, 5.8/351W) 1 09-19-2002 10:53 PM
96 f250 s/c 4x4 5.8l hp & torque specs DannyP 1987 - 1996 F150 & Larger F-Series Trucks 3 01-23-2001 12:09 PM


Go Back   Ford Truck Enthusiasts Forums > Performance, Engines & Troubleshooting > Small Block V8 (221, 260, 289, 5.0/302, 5.8/351W)

Tags
1987, 1990, 1994, 1997, 351, 58, 58l, engine, f250, ford, horsepower, motors, specs, torque, truck

Thread Tools Search this Thread
Search this Thread:

Advanced Search

Posting Rules
You may not post new threads
You may not post replies
You may not post attachments
You may not edit your posts

BB code is On
Smilies are On
[IMG] code is On
HTML code is On
Trackbacks are On
Pingbacks are On
Refbacks are On

Forum Jump


Participate In The Forums

Create new posts and participate in discussions. It's free!

Sign Up »





All times are GMT -5. The time now is 12:24 AM.


Powered by vBulletin® Version 3.8.7 AC1
Copyright ©2000 - 2014, Jelsoft Enterprises Ltd.
Advertising - Terms of Use - Privacy Statement - Jobs
This forum is owned and operated by Internet Brands, Inc., a Delaware corporation. It is not authorized or endorsed by the Ford Motor Company and is not affiliated with the Ford Motor Company or its related companies in any way. Ford® is a registered trademark of the Ford Motor Company.

vbulletin Admin Backup