bronco rpms

[famousguy_fsas]

so now that i got a new bronco i realized a few things. well my 87 seemed to run good i knew it slipped a little when cold. it was a 5.8 but my new one is a 5.0 well my 5.8 always seemed a little weak. at 65 mph it would be at 3000 rpm. though it was normal cause i didnt know any better. and i thought that truck should of had more get up and go. well my new 5.0 is way more powerfull and has way more get up and go. i noticed this one is a 2000 rpm at 75mph. so is that normal for the diff engines or was my 5.8 tranny slipping more than i thought? which engine do u think is better?

 

[Seabronc]

The RPM has to do with the wheel size and differential gearing. My normal RPM with 31 inch tires and 3.08 gearing is about 2150 RPM at 65 MPH. That is easily calculated by the following formula: MPH x gear ratio x 336 divided by wheel diameter will give you a close reading of what to expect when the trany is in a 1:1 configuration which is normal for 3rd gear not in OD.

So if you had a 351 with a C6 then depending on the gearing and tire size 3000 RPM may have been normal but without that information it is not possible to answer your question. Another variable is if you had the correct speedo if it was a cable driven speedometer.

Good luck,

>-

 

[desertbronc]

ok putting what seabronc said in simpler terms. ur new bronco has overdrive, ur old one probably didnt, thats the lower rpms on the highway. the power thing is that ur 5.0 is probably fuel injected, and ur 5.8 had a carb and probably stock.

technology is a wonderful thing

personally i like my 5.8, wich has a few mods, with my C6, has ALOT of grunt

 

[famousguy_fsas]

well my 87 was 5.8 efi and had over drive and my 86 is 5.0 efi as well and has over drive. hmm... my 86 has some stage 2 power chip or somethin in it though and all eccel wires and ignition system and everything else also.

 

[Seabronc]

well my 87 was 5.8 efi and had over drive and my 86 is 5.0 efi as well and has over drive. hmm... my 86 has some stage 2 power chip or somethin in it though and all eccel wires and ignition system and everything else also.

That stuff may make a big difference in performance, but both engines will run the same RPM at a given speed / wheel size / transmission / rear end gearing configuration. The variables you don't seem to know is rear end gearing and tire size on each. My guess is that they have different rear end gearing. Without knowing what all the variables are, you are not comparing apples to apples. If those are all identical then it could be a transmission problem.

Good luck,

>-

 

[92pobronco]

your timing on the 5.8 distributor was probably not tuned correctly to give you that get up and go your 5.0 has...... get a timing light