Wacky Dyno numbers, what's wrong here??

[BushWakr - RIP]

I made an appoint. and went in today for my "rain check" dyno run at BD.

After about 1 1/2hrs wait (it was a free run though) I finally did the run.

Since I've only seen one or three of these things, whats wrong here if anything?



'93' W250 4X4 CC Auto 8' box ( see sig for mods. )

I think the weight is actually 7500 lbs not 6500 as data entered. Does anyone know for sure what this model weighs??

Dyno synchronized at 2000 RPM.



I don't think these numbers make sense. What's your opinion guys???





bob.

 

[Grey Wolf]

BushWakr,



Those numbers look good to me! My truck weight is 6160 lbs with a camper shell.

 

[nascar mark]

My 93 W250 C. C. weighed in at 7250# with canopy. Did they test in drive or o. d. ? RPM's look funny. Way too low for those numbers???????????????

 

[paccool]

Bob,



I bought my truck used and when I registered it in Calif. it had to be weighed. If less than 6000#, was a savings on reg fee's. Took everything out and only had a 1/4 tank of fuel. Official weight was right at 5600# EMPTY.



When we were at Sacramento drag strip last fall, I weighed it without me in it. Was 6250#



Your's will be heavier due to 4x4.



GOOD torque number! I'm running at about the same boost but I don't think I have that kind of Torque. I'm guessing the HP on mine is 200-210 and the torque about 550. Had a run after the pump was rebuilt but the timing was screwed up big time. Have that fixed now, need another dyno run to see where things are at now.

 

[DieselBuzz]

Lbs

BushWakr,

If those are accurate, you could go tell some 2nd gens to kiss your..... I digress, my w-250 cc weighed in today at 6500 #s with me, the lab (Chloe+/-70lbs), 1/2 a tank of fuel, some tools and an oak pallet. I vagely remember 5900#s very empty at the dump. I've gone as high as 9000#s w/ a load of fire wood. Your weight would depend on what you carry. 6500#s seems like a feasible number to me.

Art

 

[BushWakr - RIP]

Well guys, I guess I need to go drop this thing on the highway scales and see what it REALLY is. For some reason I always thought it was between 7000 - 7500 lbs.

6970 stick in my head for some reason. Is the GVWR per axle added together to get dry weight? In the manual this body style (type 32, 4X4) is listed as either 7500 or 8500 lbs. so I'm confused.



Anyway the torque numbers seem holy heck high to be sure. The operator commented ... " wow thats a tight TC"... .

I know the engine was up near gov. speed just by sound but, was not close enought to see the tach, or the EGT



Grey Wolf,

Is your truck the same as mine, including 4X4? Have you dyno'd and what did you get if you did?

How much of an impact will result from having the weight wrong by 500 lbs + or - ???





paccool,

That torque is max, but at max HP the torque calculates out to be

(HPx5252)/RPM = 535 lb ft. if I did the math right and the formula is correct.

The max of 737. 5 at 1,480 RPM is a big surprise. That is a result of a very tight TC and is one reason why I'm changing out to an 89% this month. I need to have a bit more spool-up. If my HP had come back higher, say closer to nascar mark's then I'd probably be ok with the 91%. Bill aint kidding when he says they connect.



nascar mark,

Yes, they dyno'd mine in "D" (3rd) just like yours. I asked about going to OD after you mentioned it here. I was told that it would throw the numbers out since it was less than 1:1.

Piers also said to use "D" when I asked which was the right gear to use for truest readings.

I agree the PRM's look off but wonder if thats just attributed to the TC/VB/Trans. setup.

Did you notice what your EGT's were on your run???

In my case atleast they synchronized the dyno at 2000RPM before the run. I don't think they did that with yours and the other low HP trucks did they?

Mark, I can't help notice the wide discrepancy between your run and mine. You're running the same basic setup including the DTT stuff, just more fuel/boost. Strange there should be that much difference between RPM figures. Are you sure you're running a 91% TC. Not trying to be smart here. Or, am I sure about mine?? LOL guess I'll find out when its changed over to the 89% mid-May.

Anyway, I'm going to try to get a run done at Cummins which is just up the road from PDR.

Here I was hoping to give you a run for nickel mark... bummed me out.



Thanks to all of you who jumped in here. I really am not familiar with the intricacies of a good dyno run, parameters, data entry, etc.

 

[Grey Wolf]

BushWakr,



My truck is a 4X4 like yours, it has the same gearing and has most of the same aftermarket goodies as yours. I don't have the Borgeson and I have the 180 Bosch injectors and a 5 speed, so I guess you could say its pretty close to same as yours. It will make 27 lbs boost and I haven't moved the timing or diaphram so it would be interesting to see what the figures are but I just haven't put it on the rollers yet.

 

[AlK]

Grey Wolf,

My 92, 4X4, 5spd, 180 Bosch injectors, 16cm turbo housing and timing set at 1. 4 put the following numbers up at the last BD Dyno Days.

Max Power: 220. 2 HP @ 2780 RPM

Max Torque: 478. 9 HP @ 1880 RPM

---

Al

 

[Grey Wolf]

AlK,



Well those numbers don't sound to bad to me! How many pounds of boost is yours putting out?

My main reason for the mods was to get rid of the lag and to give the truck a little HP increase which I feel I accomplished.



Thanks Ken

 

[Gary - K7GLD]

HMMmmm - I'm trying to figure what the WEIGHT of the truck has to do with max HP and torque in dyno readings, in anything other than computing quarter mile capability! And if THAT had to be factored in for any reason, so would wind drag and rolling resistance values...

 

[BushWakr - RIP]

Gary,



Like I said I'm a beginner when it comes to dyno runs, so I don't know if it makes any difference at all. I would take a wild stab and say that I wonder if it makes a difference in the way the rollers are controlled during loading. Perhaps it simulates the inertia properly based on weight. Now, for all I know it could have nothing to do with it,, but then why enter different weights or any weight at all then.

I do notice that the boost numbers of some of the other 1st Gen guys seem a bit higher than mine, but I don't get to see the smoke/EGT ranges they're generating either.

You'll notice that AlK, nascar mark, and most of the other fellas all have their numbers based on significantly higher RPM's in both catagories as well.

I'm having some smoke with my setup currently, even a bit at idle, but I'm not getting 27 ++ psi boost so that needs to be thought thru with Piers or someone qualified to make an educated guess.

If we assume 160 HP stock (flywheel) and also use a correction figure of 20% (I don't think its that high) for driveline losses, I am roughly running about 270 HP @ flywheel. (225 HP + 20%=270 HP)

With my mods I was expecting to see about 270'ish ( + or -) to the wheels, not 225 HP.

Time to rethink perhaps??? We'll see.

OH GREAT !!! Don't tell me I need one of Piers' magic VE pumps just to make 300 HP:--) :--)









Scary torque number though, 737. 5@1480, sheeshh !



Bob.

 

[paccool]

Bob,



I'm like you and don't have a lot of experience in this area but all the folks in the know seem to feel the VE pump is only capable of about 230 HP. I assume that is Flywheel HP?? If it is rear wheel then flywheel will be 20% or so above that to cover the loss thru the drive train. (Depends on if it is stick or auto transmission).



Seems to always be major differences of opinion on this subject - how bout it guys, anyone know about the different type dynos and the HP capabilities of the VE pumps?

 

[nascar mark]

Something is wrong with the numbers from your dyno sheet!!!!!



1st with the stock cam in our 93's our max hp should peak +/- at 2600 rpm's.



2nd our torgue should peak at +/- 1850 rpm's.



3rd you said they ran the truck at or about gov. speed by the sound of it. If so your rpm's on the sheet should have been +/- 2800. According to the sheet they didn't go past 2200 rpm's. ????



All i know is they were consistant with the way they dyno'd the trucks in the 1st half of the day at dyno days. They did yours totally different then any other truck that day?

My sheet that day doesn't even start until 1750 rpm's and goes to 2800 rpm's were they let off. I know i can turn 3200 rpm's in "D" as i do just about daily having fun. With the 35#'s boost =350 hp at flywheel, my truck makes in "D" and - 22% drive line loss due to thicker gear oil in all wet area's of my truck & posi ='s the 271hp at rear wheels at 2680 rpm's the dyno sheet spit out. The torgue numbers also mesh with the math = 698. 1 ft lbs at 1980 rpm's.

The numbers don't add up on your dyno sheet?????????????



My invoice says 91%tc from DTT. I was wanting the 92% but Bill didn't have one on the shelf for a 1st gen as he said not many can turn it. My set up is the same on paper as yours but very differently set up due too my tinkering with the pump. The truck will fog big time even with the power screw "turned out" or "backed out" from factory setting and still make 35#'s boost.

Which is the reason i'm getting max fuel and produce higher then normal hp for a VE pump.

 

[JLEONARD]

I am learning a lot by following this thread.

It has my interest peaked since I am planning on getting on a dyno next weekend.

As you can see from my sig I have not done much to my truck, so the numbers will be a good baseline... at least for me.

I will let you all know what the numbers are next week if I can get on the machine.

 

[Lil' Dog]

Crank Trigger??

How does this dyno get RPM???? If its off of the rollers you're screwed with an auto... I would assume that they use an optical sensor on the crank right??



I think that the RPM scale is wrong on the bottom of the sheet. But I would think your HP would be higher with your mods.



I still don't know what weight has to to with the HP???





J-eh

 

[Gary - K7GLD]

When I had my truck dyno'd on a Mustang dyno, they didn't say anything about truck weight - so unless the dyno software itself provides typical weights for various vehicles, it was not used to arrive at power/torque readings - after all, how many guys really KNOW how much their trucks weigh? If it WAS a factor in Dyno figures, it would seem that the dyno operators would ALSO have to have scales available to be certain of data...

 

[AlK]

Grey Wolf,

I usually don't watch the boost to closely, but I know I have seen the gauge up at 25 so my guess is that maybe 26 -27 would be maximum. I will find out.

Bob,

I know your truck is an auto and maybe that is the reason that your truck reached the max HP at only 2200 rpm, but I would have thought the max HP would be reached at over 2500 rpm. I was watching the dyno for quite some time at the Dyno Day and it seemed to me that trucks were reaching the max HP near the upper rpm levels. In addition at Dyno Day I noticed that when they ran my truck and also on others there were two runs after the first run the Techinician would make some changes to the computer and then they would take the second run. On my first run the numbers were just over 200 but the final run yielded 220. 2 Something does not seem to be right!

---

Al

 

[ggorremans]

My turn at the BD dyno last month gave me only one run, Al. No mention was made of truck weight, only rear end ratio.

Gary

 

[Old Smoky]

I ran my rig at BD Dyno Day. They didn't ask me any questions about weight, gears, or tire size. One of the guys just jumped in and drove. I think that gearing and tire size would be very important. The rpm scale on my printout cant be correct. They don't know what rear end I have, and did not compensate for the larger tires. I also noticed that the test only went to about 2650-2700rpm's. Why not run it to the governor? I don’t think that weight would really make a difference. Except for in cases such as Piers. Where he gained about another 75hp or so by having a few guys jump in the back to keep the tires from spinning.



I think that my numbers where pretty close though. I make 20+psi boost, and made 203hp.



Mike

 

[MikeO]

Weight

Weight doesn't have an effect on anything but the simulated 1/4 mile run. Since you are not actually moving a static weight (vehicle) the computer knows how to account for this and come up with a rough 1/4 mile time. The computer's result is always lower than what you get at the track because, let's face it, a pickup (esp. 1st gen) is about as aerodynamic as a 4'X 8' piece of plywood.



Mike O.



PS More weight in the bed is good because it helps cut down on frictional losses from tire spin