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Cruising RPM - whats yours?

Keeper

Keeper

Active Member
After finally getting my speedo calibrated and the torque converter to actually lock up I have my cruising RPM.

My setup -

engine - SBC
trans - 700r4 trans
Rear diff - jag with 2.88
Rear tires - P295/50R16 27.6 diameter

Cruising at 110 km (68mph) I am running right at 1500rpm :O

Should be good for the gas mileage I think.
 
Does it seem to be a bit boggy if you put your foot into it at highway speeds? Or do you have enough HP to handle it? I am set up with a 305, turbo 350, Blazer diff (ratio unknown) and 31-16.5-15 rear tires. At 65mph my tach runs at 1950. Snaps the head pretty good when I put my foot into it.
 
With Lock up overdrive, I guess that is good. It sounds low, but that is the objective and in a light wt like the T, it should deliver good mileage. I'll bet most of the Detroit iron has a cam that the torque curve starts above 2000 rpm. I am running a C-4 trans so high gear is 1 to 1. I just changed gears and shot for a 2000 rpm cruise. My thoughts were I could stand the rpm and be just at the start of the torque curve. If I had OD, I would definitely use it. Anyway I cruise at 6200 rpm!!!!, just kidding. I do good to get over 55 mph.
What small block chebbie do you have?
 
Its just a 350.

The 1500 RPM is right at the start of my power band, well where it theoretically is. All the parts were matched for 1500-5500 RPM range.

When I put my foot in it, it downshifts as it is supposed to and off I go. You can feel a "bog" when you are at a steady cruise though. I knew with the gearing in the rear I would probably run into some minor issues, but I had no way of knowing with driving it. I have a longer cruise planned for this weekend so I will get a better test on how things actually feel.
 
I have a SBC 350 that is .040 over for 358 cubes. It has a Turbo 350 trans with a B&M "Holeshot" converter (1900-2100 stall) that is turning an Eaton 4.10 posi in a '96 S10 2wd rear and I am running 285/70x15" rear tires that are 31" tall. At 3000 RPM I'm doing 67.51 MPH. When I was running 275/60x15" tires I was running 60.98 MPH at 3000 RPM.

Jim
 
The only thing I would be wondering about is trans pressure. The 700 needs a lot of pressure and at just 1500 RPM, and less at lower speed, I would wonder it the pump is turning enough RPM to build enough pressure to keep the trans from slipping and burning up the clutches. I don't know if it will, just wondering if it could. Does anyone know for sure?
 
Not done building yet, but, with Ford 302 & AOD, 3.55 diff with 26.6" tires, should be right about 2000 RPM at 65 MPH.
 
RPM said:
The only thing I would be wondering about is trans pressure. The 700 needs a lot of pressure and at just 1500 RPM, and less at lower speed, I would wonder it the pump is turning enough RPM to build enough pressure to keep the trans from slipping and burning up the clutches. I don't know if it will, just wondering if it could. Does anyone know for sure?
Click to expand...

Thats a good question. I would have never even thought of that! .
 
I designed it that way. Knowing the AOD gears and the diff I chose [3.55 of 3.73 Ford 8.8], I chose a tire that would give me about 30 to 35 MPH / 1000 RPM.
 
I went for a drive today and I'm at 3,000 rpm and doing about 65mph. Seems about right and matches a little RPM/MPH guide that ExJunk sent me way back when.
 
Well, I went to cruise night tonight.....up in the big city. My little blown inline 6 cylinder, with a turbo 400 W/ MANUAL VALVEBODY, TCI 2800rpm converter, 3.90's w/ 33" Hoosier sprint car tires out back, 3000 rpm @ 80 MPH.....just got back. my first run without packing 1/2 my toobox in the trunk. Found out I'm gonna have to safety wire my motor mount bolts into place. They loosened up, evidently when I did a coupe of burnouts.
 
Screaming Metal said:
Well, I went to cruise night tonight.....up in the big city. My little blown inline 6 cylinder, with a turbo 400 W/ MANUAL VALVEBODY, TCI 2800rpm converter, 3.90's w/ 33" Hoosier sprint car tires out back, 3000 rpm @ 80 MPH.....just got back. my first run without packing 1/2 my toobox in the trunk. Found out I'm gonna have to safety wire my motor mount bolts into place. They loosened up, evidently when I did a coupe of burnouts.
Click to expand...

Please be so kind as to allow me to say:

"Without pictures, it didn't happen"

Meant in the nicest possible way, but when do we get to see a pic or two of this beast? I'm consumed with curiosity... :spy:
 
and to keep this on track. I haven't a clue as my rig continues to cruise in a storage unit.

2200 stall, 355 chev, 387/418 hp/tq (or so the 'corrected' dyno sheet from the Blueprint says), 3.55 final, 27.9" OD tires. Where's that chart when I need it?

<edit> I found an online calc that allows you to factor in converter slip - 2600-2800 @ 60 ballpark. I will probably go to taller tires eventually. For some reason, I'm thinking that what it currently has isn't going to last long...
 
DontCallMeJimmie said:
Please be so kind as to allow me to say:

"Without pictures, it didn't happen"

Meant in the nicest possible way, but when do we get to see a pic or two of this beast? I'm consumed with curiosity... :spy:
Click to expand...

Hahaha!!!!, yep, well, I've always had problems posting pics on here, usually I copy and paste, but since I tried that in the 'Turbo 350 vs PowerGlide' section the other night, that didn't even work. hahaha.....I don't like the idea of opening up a facebook page because of the feds using facial recognition software, storing everybodys profiles and such. Thats why my shop has such a small website. I'm also bound by contract not to let folks see the inside of the shop, because of race cars and such being in and out.
Big Bros. is too Big and Too Nosey for my likes, so, since I'm closing in on the end of my life, ya'll see it cruisin' the streets at some of the runs. Its all black and has a rollbar (I'm very safety conscious)(thats a nice way to say I'm scared!) and a all alum. billet 6 cyl. with a blower.
Yes, tried posting pics, won't post.......
 
EX JUNK said:
Screaming Metal, I think that your speedometer is off a little. By using this link, http://www.dennysdriveshaft.com/potential_speed_calculator.html, your figures of 3000 RPM with 3.90 rear and 1:1 final drive with 33" tires equals 75.5 MPH. Jim
Click to expand...

Hi Jim, yes, I figured as much. I'll ditch the VDO speedo thats cable driven for a electronic unit, I'll let that be one of my Christmas presents to myself. But still, I like the safety margin! ha!
 
Screaming Metal said:
Big Bros. is too Big and Too Nosey for my likes
Click to expand...

Given the number of background checks, fingerprinting and drug tests I've submitted to in the last 3 years, any pretense of me having a private life is pretty much illusion. That's what I get for choosing to work with/for Financials. These days I'm in consulting and sales engineering but still having to submit to The Man on occasion.

Not quite the "cost of freedom", more like "the cost of being allowed to survive"... But that's way off-topic and as much as I'll grouse about it in public.
 
Pics taken in the driveway are cool. And cut & paste from Photo Bucket is as easy as it gets. I WANNA SEE IT!! LOL
 
I saw something on posting pictures that provided information on the location. Also google earth provides a snapshot of almost any driveway, rooftop shot in America. I guess any efforts to protect your privacy is good.
 
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