GoRideSno

Finally went to the dyno today for the first time ever w/ any car.

This was a dyno day so I couldn't do any tuning.

We got the IC circulating water at about midnight last night.

I made 4 runs. These are the best 2 above.

This reflects rear wheel HP of course. (Not long ago I wouldn't have known that.)

All runs were made in 3rd gear.

I have no heat exchanger on my IC system yet. I was using a 5 gal tank as a reservoir. Water temp was probably around 60 degrees F.

Boost was just over 7psi measured after the IC core, 1.25" above a port. I suspect 1 psi pressure drop because of some flow restrictions with this specific prototype unit that will be improved.

Core thickness is only 2.5". It's also 6"x7". I have 2 bigger ones from Spearco/Turbonetics that will work better but this one is significantly cheaper.

My car has almost 120k mi so I suspect my base-line HP would be less than new/stock.

Stock chp at 3000 rpm is about 190. Dividing the SUPERMODEL's 212 rwhp by .80 gives 265 chp. (282 if you divide by .75 )

Stock chp at 3500 rpm is about 205. Dividing the SUPERMODEL's 245 rwhp by .80 gives 306 chp and by the optimistic but sometimes used .75 gives 326.

Max Torque occurs between 2500 and 3500 rpms at about 374 rwtq, dividing by .80 and .75 respectively we get 467 and 498 crank torque.

SUPERMODEL’s max rwhp is 349 at 5400 rpms. Dividing by .80 and .75 we get 436 and 465 crank hp v/s the S4’s stock figure of 316.

With each run the power improved. Since all I did was adjust the throttle cable and purged the very hot water from the reservoir and refill it with cold water I suspect that I would have gotten close the to the 400 rwhp mark had I had a chance to look about the engine bay a bit. (I know excuses, excuses) I had expected 425 rwhp but thought I was going to be making 8-9 psi and using one of the Spearco cores.

Not bad I guess considering many of the parts for this prototype came from the local hardware store and every part I designed myself.

Normy

Hot hot hot hot!

My hat's off to you! GAWD I'd just love the 260 rwhp that my '85 S2 is supposed to give!

Normy!
'85 S2 5 Sleep

Tony

Congrats Andy, looks like youve got a good starting point.
Youve worked hard. You defintiely got the low end grunt back in the car..!
Once you get the IC sorted and the flow, i think you will see the TQ hold up near the later part of the run..

Did they have a sniffer for the fuel air ratio?

QUOTE]We got the IC circulating water at about midnight last night.[/QUOTE]

Burning the midnight oil again huh!

GoRideSno

Thanks Normy.

Tony,
Yep, my assistant Sandy and I have have burned quite a bit of midnight oil lately. Between this and my job I am getting burned out. Not as burned out as my tires though. I pulled out onto a street last night and porposefully tried to burn out. I couldn't believe it, dark black rubber on the pavement for well over 100 feet and smoke billowing. I was frightened that the fire department was going to come. Going straight from a dead stop it dosen't spin that much though.

Andy

lifewithbmw

Hello.

Andy the dyno was great! And thanks for the tacos.

I wish I could of dynoed my car.

slate blue

Excellent Andy really enjoyed your post, love your supercharger setup! Goodluck in the future.

Dozman

Appreciate the burning the midnight oil. There seems to be light at the end of the tunnel.

Lagavulin

Andy, good job!
Is this the whipple?

If it is no more than 1 psi then you're in pretty good shape as Corky says to keep the pressure drop 1 psi or less.

You can do a leak-down and compression test to ascertain the condition of your engine. Even though it has 120k, it may still be in good shape. If you have any doubts, have it tested! That way you'll know one way or another.

Just go all the way and divide by .50!

No, it's stating observations, observations.

Using .85 IC efficiency and .80 for drivetrain loss, I came up with:

06.2 psi makes 350.3 rwhp
10.3 psi makes 425.6 rwhp

Hmm, you stated you were a little over 7 psi for the run, so I changed the drivetrain loss to .75:

07.0 psi makes 349.3 rwhp
11.1 psi makes 424.4 rwhp

The calcs won't be exact; they are there just to provide good, ballpark figures on what to possibly expect for a given hardware combination.

No, that's very good; looks like you have a solid foundation to build upon!

And thanks for posting the dyno results for all to see.

Tony

On the subject of leakdown tests. I actually have 2 of them now. The one i got from Summit racing arrived last week (back order) and in the mean time i had found one here in Vegas.....forgot to cancel the Summit order. Instead of returning it, I thought Id offer it up for use here on the list.

I figure 10 bucks rental and you pay shipping (to and from..89135) I suppose if one person has it, they can forward it to the next when they are done?

Just an idea..but if any one needs acces to one, let me know.

This is the item.
http://store.summitracing.com/partde...t=SUM%2D900010

GoRideSno

Thanks everyone!

It looks like my assistant Sandy has introduced himself as lifewithbmw. Trust me he likes 928s too. I'd say he has put in at least 200 hours working on mine.

Lagavulin,
Yes this is with the Whipple 2300AX.

I have done several compression tests but no leakdown. The compression tests all came out with all cylinders varying less than 10%.

I really don't know a fair figure for the drivetrain loss. The recent article that Z posted showed .20 and .25 for the auto transmissions drive loss. The guy that did the test said the car should be able to do only 100 mph in the gear used to test. My car will do 140 in third and has 265 35 18s.

How high do you think I han go on the 30# injectors?



Andy K

Tony

Even though the TQ drops off in the 5500 range, the appealling thing is that the bluk of the TQ curve sits in the realm of everyday driving rpm and down where this car needs it! I hate being in 2nd gear at 30-40 mph..foot to the floor and the frikn thing wont kick to first. ( you have to be below 25mph per the manual)
The car just seems to sit there. Its like, "COME ON...get going would ya!!" Its a pig at that point.


I think ill go do a little experiment. I want to see where the Rpms drops to in my car after each successive shift. 1-2...2-3...3-4.
Time to find an open stretch of road

John..

Nice fat torque curve as would be expected on that type of blower.
Good work, just be careful as you push out the envelope...you have made great strides thus far with that car and probably hold the record for the best bang for the buck...plus that is a good street HP number.

Z

Interesting to see the power curve and compare it to the centrifugal dyno chart power curves.

The 20% figure is closer for the 928 A/T. Ideally they want you testing in the gear that provides a 1:1 ratio, which would be fourth gear. You can't do that with your car though because it would be over 200mph when at the top RPMs. The dyno will shut down at 200mph and will abort the run.

Tim Murphy's 525+rwhp was done with 30lb injectors. I'm not saying that's optimal, but just that he made that much power with the 30lb ones.

If shifting at 6,200 RPM, it will drop from there to about 4,000 RPM when it shifts to 2nd gear, and from 6,200 RPM to a little over 3,700 RPM on the shift from 2nd to 3rd. When shifting from 3rd to 4th, the drop is from 6,200 down to a little over 4,300 RPM. The drop for the 1-2 shift is about 34%, for the 2-3 shift it's around 40%, and for the 3-4 shift it's around 30%. You may notice that the RPMs never drop down below the flappy activation point. If you floor it off the line, the flappy will change position only one time in first gear, and it remains in the high RPM resonance position the whole time after that, since the bottom end torque increase it provides isn't needed again.

Tony

Sure, thanks Z, try and spoil my fun.

Im going to go try it for my own enjoyment anyway


Looks like those numbers would just land on the healthy part of the TQ curve through each shift..just before it starts to slide.

Z

Of course you should verify it. Might be a good idea to do a number of runs too, just to make sure that there were no weird anomalies or anything. Yes, it's tough work but someone has to do this kind of stuff in the interest of science and education.