Those are excellent results.

See what can happen when there's time for a thorough custom tune?

I rest my case.

It's simply got to be better than a quickie.

 

actually you are wrong again... but who is counting
we stopped tuning last time do to a fueling issue that was later resolved

 

it depends on how the dyno is run and the type of dyno it is. Really, what is measured is torque vs RPM. What can effect this at the wheels is a really, really long list. But for the question about gear used to run, there are basically two things that fight each other. The lower the gear ratio, the less energy is put into the rotating parts of the engine (like the flywheel), so this pushes wheel HP higher. The thing that fights this is that frictional losses out of the tranny, at the hubs and the deformation of the tire increase (as they're going faster for a given RPM) tends to lower readings. What wins? Who knows! One nice thing about dynopacks (the ones that bolt to the hubs ) is that you don't have to worry about how hard you're tying the car down to the rollers, tire pressure, and deformation losses, or wheel/tire mass.


Matt

 

That's OK. I'm used to it.

But I didn't realize that because Larry's post about the first time didn't touch on tunus interruptus.

So do you believe that a longer time to pay attention to the little issues that arise (like flat spots, stumbles, poor idling, etc.) is of no advantage over the dyno-day tune? This is really the only point I was trying to get at in the other thread.

 

My base tune takes care of "flat spots"... doesn't yours?

 

I don't know. I don't do tunes. Do you mean LDG?

I mentioned flat spots because I had one early on and because of this statement in the first post of this thread:

"He smoothed out the torque curve, got rid of the 3,000 rpm flat spot and slightly increased the WHP and torque from the already amazing RMW tune from last week."

It's not a challenge, it's just a question.

 

HP is a measurement of how much power can be applied for a given amount of time.

To say torque makes you accelerate and HP gives you top speed is misleading. HP is basically how much torque you can use over a given time period.

The higher the HP numbers, the more acceleration you will gain. However, using only peak numbers will not give you a clear picture of which vehicle will accelerate faster from x speed to y speed.

Torque/HP curve come heavily into play. For example, a car that makes 400 peak HP for about 100 0 RPM may make only 200 otherwise. (exaggerated). A car making 350 HP across a 4000 rpm range will be faster but show a lower peak number. I hope this makes sense.

 

make a thrust curve for the car (torque at wheels vs speed for all gears). This will give you best shift point for fastest acceleration. You can ignore wind resistance here, as for any given speed, the wind resistance is independant of gear.

To figure top speed, plot the above vs wind resistance. When the wind resistance drag intersects with the thrust, you have the max speed.

Matt

As Scott pointed out, HP is proportional to torque times RPM, so they really aren't indepenant curves.

 

Torque is directly proportional to acceleration. In fact, you can tell what you need to know about a car's acceleration from the torque curve, because horsepower is simply derived from torque (horsepower is directly proportional to torque times speed).

It's true that *peak* numbers don't mean much, but for two identical cars at the same RPM, the one with more torque at that RPM will accelerate more quickly. The HP at that RPM will be higher as well, but the horsepower is a by-product of the torque - it's not the reason for the acceleration.

 

I never touched the map there
we fixed the fueling and the map I had on there fixed it

 

I'm not Jan.... but I tuned MINIs with 100 K on them... still made a 25 WHP.... and X tourque... so I imagine it always matters.. cuase tuning yer car is important.. infact more important if it's older IMO

 

My Mini has 95K on her.. Prolly over 100k by the time my January 19th tune date comes around with Jan. My car hasn't ran better! And can't wait to see the results from Jans tune!!!
I think our Mini's are just breaking in at 100k, . (that is, after you buy a new SC, hahahahah).

 

Ok, now that a third dyno sheet has been posted in this thread from a dynapack dyno, can someone now explain to me why Alta uses a 4.1 gear ratio, on the first two dyno sheets in this thread Jan used a 4.61 gear ratio and on this last dyno plot with 245.8whp and 181tq Jan used a gear ratio of 4.48. I really don't understand!

 

but to do before and after, you should choose the same gear to do both pulls. Then the drivetrain losses and inertial effects are about the same, and the % change has a bit more value.

If you have an older car that has a true 1:1 ratio, then that gear would have the least loss, as the countershafts wouldn't be involved. With our folded Getrag 6 speed, there's no such thing as a 1:1 ratio. Also, 02-04 cars have different ratios than 05+, so you can'd do it at the same ratio for those cars.

If you really want to learn the details of all this, there are books that explain the pros and cons. But really, you shouldn't be looking at the peak numbers, as a lot goes into day to day/ car to car / dyno to dyno differences. Look at the % changes over the entier torque curve (area under the curve), and that tellls you more than any peak HP number ever will.

Matt

 

this is accually incorrect... but who woulda thought that was possible with too much technical data and blahdy blah blah...

you get higher numbers from using a higher gear.. when I say you I guess I mean me... cause I have tested it repeatedly... 4th is close to 1:1 for the mini... but the #1 reason we use 3rd insted of 4th is because it is MUCH harder on the CAR... when you finish a 4th gear run you are going 110.. I dont think anyone has a fan that comes close to generating proper cooling... LOL.. but if you dyno in 3rd you still get accuarate #s per that gear... (provided you knew how to set thing up in the first place..) and it's much easier on the car....

This is back to the old it's in the deltas disscussion... honestly if Alta uses the same ratio on your car.. then in the end... that's all the matters... and I have been to prolly 20 different dynos... and I have never seen any huge difference between any one of them that matters... from Dyno jet, to dynapacks, to Mustangs... etc... the % of differences doesnt matter enough for it to really show in our cars.. Most I have seen was 10 WHP diff...

anyway... this I am sure is going to be another internet expert roundy round technical blah blah in the end.... so.. enjoy the disscussion and remember.. all the blahdy blah doesnt really matter..

 

I think that's exactly what Matt was saying. When you use a numerically-lower gear ratio (i.e. a "higher" gear), you get higher dyno numbers.

 

the longer the gear the higher the HP...it takes more effort for the car... so if everything is set up correctly... you will get a higher #

unless I am still misunderstanding... when I said higher... I meant 4th vs 3rd

 

just landed in Denver Snowing and cold
Ripper
that is the gear ratio for 4th gear on older trannys

 

what is the gear ratio for 06 trannys?

 

snow SSSSSSSuuuuuuucccccccccccckkkkkkksssssssssssssss!! !!!!!!!!!!!!!!!!!!

 

4.61 for 4th

 

higher ratio is lower gear....

Matt

 

rocket sugery

I was speaking in non technical blahdy blah

 

It's really great to see all these cars pulling such awsome numbers. I'm really happy to see Jan's work paying off for him. He really does care about the Mini community which is why I have been with him from the start. Hell, I have shipped almost every RMW product to date just because I like this donkey. Not for free of course .

Here is my old chart with Jan's first head and the stock tune. I'm lucky because I really did get one of those stronger engines from the factory. I have great TQ.

With only changing the Eaton to the Rotrex we went to 251whp and 196ftlb at 7000. We ran out of fuel and reached the limit of the stock intercooler.

We should have some fun news next week or the week after depending on Jan's Schedule. The fuel and intercooler limits are no more and Jan's going to live on the Dyno for a couple days developing the tune for the Rotrex Kit.

Anyone want to start a pool to guess what the final WHP and TQ will be 8000rpm's????

Lognboard

 

282.47 HP and 210 ft/lb.

What do I get if I win?

mb