Disappointing Numbers

[TSuter]

Just got back from the KSHE 95 car show. They had a Dynojet there, so I figured what the heck. Made four runs, only one of which got a decent reading. That one run showed a max hp @ 153. 72 and max torque @ 342. 37.



I wasn't expecting BGilbert's kind of numbers, but with the tweaks I've done I was hoping for at least better then stock! What am I missing here?



Take into consideration, it was my first time on a dyno, and the kid running it admitted he was new.



TIA



Tom

 

[cerberusiam]

Well, if you haven't upgraded the transmission your loosing 30% right there. No sticks either if your sig is correct. Numbers don't look too bad given the above.



Did you lock it in OD and drag the brakes to get some boost up before you started the run?

 

[TSuter]

All the runs were made in 3rd with OD locked out. They applied brake power to the drum on the Dynojet(?), I was able to get 24lbs boost on all the runs.



The current injectors are the originals with @210,000 miles on them. New ones are waiting on the wallet to get a little thicker. I knew injectors would make a difference, I just didn't think they would make that big of a difference. An HX-35 would be nice too.



Transmission was upgraded in Dec, with a TCI converter from Summit as well as being rebuilt.



My seat o' the pants meter says the truck is running much better/stronger then when I bought it. I assumed when I bought it I was starting off with 160/400 with nowhere to go but up from there. Wonder what the numbers would've looked like then?





Tom

 

[cerberusiam]

You left a little on the table running it in drive. A DynoJet is an acceleromator not a load dyno. Unless it is equiped with the extra weights and a very savvy operator it won't load a diesel engine anywhere near potential. that is why you lock it in OD and drag your brakes to get enough boost to start the fuel. Your TQ numbers will be much better but the HP is rpm dependent so your close there. Remember a diesel is load dependent, it will only produce the power needed to do the job and leave the rest.



Depending on what TC you got, it is probably not much better than the stock ones. The TCI's were a bit tighter but still did not handle the TQ multiplication as well as the better ones so there is a fair amount of loss in the fluid coupling.



The 160/400 was flywheel ratings on a good day with a friendly operator, not rear wheel ratings. A lot of stock auto trucks will not make much more than 130 HP measured with a few tweaks so your going the right direction. Take your numbers and divide by 70% for a better estimate of output:



Measured HP @ 154/. 7 = 220 flywheel



Measured TQ @ 342/. 7 = 488 flywheel





That make you feel better?





If the 24 psi was max boost your a little short of fuel yet, you should be able to push that to 30 with a 16 housing. Your starting to push hot air at that point but one can get some decent numbers with it.



Don't sweat the numbers for being low. Your going in the right direction so use them for a gauging whether your mods are good or bad. A dyno is a tuning tool and not the only way to gauge performance. If the truck does what you want, makes decent mileage, and is FUN the numbers are just numbers. Cheers.

 

[bgilbert]

cerberusiam pretty much nailed it all. Well put. I also thought it looked about right for your setup. Philip and I watched a 1st gen auto dyno at Scheid's event a couple years ago, and IIRC, it did something like 120ish hp if that. His torque number was even more sad.



Some of these trucks left the engine plant right at 160hp flywheel, some less, some higher. My 89 stock, unmolested injection pump, caps still in place etc, did better to the ground than 160/400. IIRC it was 170ish, 417ftlb on a dyno jet. Previous still says it pulled better than the 02 he replaced it with:-laf!

 

[Greenleaf]

You gotta really load that thing down in OD. A local guy dynoed his when there was a local dyno and it put out a little over 200 to the rollers. He too was saddened by it. It was operated by a classic car restoration shop. 45. 00/three runs. It wasn't worth it.



Cerb must have felt your pain. I don't believe I have read more than thirty words from him in any given week. He did well.

 

[DBF]

My seat o' the pants meter says the truck is running much better/stronger then when I bought it. I assumed when I bought it I was starting off with 160/400 with nowhere to go but up from there. Wonder what the numbers would've looked like then?

Tom

Mine, stock, turned 134 rwhp. Then the fun began. Regards, DBF

 

[TSuter]

Thanks for all the replies. It makes much more sense now. Just another reason why I like the TDR so much, you guys are a wealth of knowledge and I'm still learning .



"If the truck does what you want, makes decent mileage, and is FUN the numbers are just numbers. " Well said, as long as I can pick on the ricers I'm happy. For now at least :-laf .



Thanks again



Tom

 

[JLEONARD]

I was at 160 rwhp when I was stock with only a 16 cm ex housing but with a manual trans.

I don't know where I am now but the truck runs good... . I may get beat but I am never enbarassed. The secret is the sleeper look... . LOL. I step on it it and she goes.

 

[glhs]

Sounds low. You have the screw in 3 turns from stock? Should be near bottomed out now. A 16 cm housing and the fuel pin turned to the deepest setting? All that should add up to 50 more hp than stock. Usually Dynojets are pretty generous, but maybe this one is stingy. What kind of boost does it make going down the road? Stock should have been about 15 psi.

 

[TSuter]

glhs,



I usuallt hit between 20 and 24lbs of boost on the road. I had posted earlier in another post about trying to get power out of the pump with those adj. I think it was Greeleaf that said something like some of these pumps all you have to do se look at them funny to get more power, some you need to hit with a sledge hammer. I have the latter.



Now at least, I have some sort of baseline to work with other then the seat of my pants, and the grin on my face.



Tom

 

[sdstriper]

Have you looked at the injection pumps throttle lever travel? There was a lot of gain there on mine. There was only one copper washer on my AFC boost tube, when I put the second one on it I gained 2 psi boost from that! There are many small things that can add up.

 

[TSuter]

For the throttle travel I had to do a little grinding on one of the brackets to get full travel.

Copper washer on the AFC boost tube?

I also recently R2d the intercooler boots, that gave me a couple extra lbs. I haven't leak chk'd the intercooler yet though, I need to find the post to make the cups to test that. Hasn't been to high on the priority list, mostly because if it is leaking I don't have the money for a new one.

Tom

 

[Greenleaf]

What's an AFC boost tube?



:-laf





ROF