Dyno Tuning: This is why you do it (56k beware)

[dr_hunt]

That's correct. Afr's where 12ish, timing was 22deg, boost was well into the 20psi range before I could get the mass airflow reading that I ran on the street the day before at 20psi. Not sure it was because of the dyno or heat in the dyno cell or what, either way I drove away from the dyno and it would ping at the same psi. What would/could have been the problem?

 

I've heard of the same problem, there's a dyno in Alb that has performed tuning on several vettes, some of which blew engines on the street after the dyno tuning sessions.

[clarkspeed]

Excellent post. I just spent 2 hours on a Superflow last week. As tempting as it is to look at that max number, I just kept making runs and programming EFI to get the A/F ratio I wanted across the rev range. End of the day I only gained 10 HP max, but made huge gains in areas under the HP and torque curves. I was able to find the best A/F ratio for my N/A engine, adjust to desired A/F across usable rev range, and find best timing advance. Dyno time seems like a bargain for the payback in power. And I had already done considerable tuning with a LM-1 before this.

[Drax240z]

One thing that could be the problem is that it can be very hard to hear detonation in the dyno cell depending how it is layed out, it is easier to hear on the street in the car at times. A very sensitive dyno will be able to show you detonation on the graphs no problem.

 

It is possible on most load control dynos to up the load to a point way beyond what you will see on the street, but again that comes down to the dyno operator. Ramp rates, gear selection, intertia settings, etc all play a role in how much load you put on the car. There is a lot of operator control, and as a result room for human error in the process. As a guideline I would recommend you look for tuners that have at least attended Ben Strader's EFI 101 course. It's not a foolproof guide, but it at least shows some interest on their part in professional development, and should mean they have the basic skill set in order to properly tune a car.

 

As for the 1/4 mile stuff Jersey, I honestly have no idea. I don't have a 1/4 mile track anywhere near me, so don't get a ton of customers that have time slips for comparison purposes.

[Nismo280zEd]

I don't want to eat into your bag of tricks here, but alot of us Houston guyz and more and more Z guys are running MS so we have alot to play with to tune. My understanding was to tune by AFR and color burn in the piston, this would yield the best mpg and torque/hp?

 

-Ed

[Mikelly]

People are complete idiots when it comes to explaining the values of tuning a car properly with the best tools available, one of them being the DYNO.

 

In my 2.5 years of owning the Vette, the car has been on the rollers four times. Once was for numbers, and the other three times were to tune. Twice on the same dyno, and twice at other locations, which does make a difference. That said, people clearly do NOT understand what they are looking at, or what they should be looking at.

 

You can tune your car for peak dyno numbers and the car will suffer majorly with drivability issues. You can tune it for peak overall power and broad range, lose a couple HP at redline and BOY HOWDY, All the sudden the car is a DREAM to drive again!

 

My 99c5 has gone through a huge transition over the last 2.5 years of owning it. And it all started when I took it to a Dyno after the first 5 months of owning it, and doing the simple mods every vette owner does.... Cat back and CAI. I remember standing in the bay and having the guy say "so what do you think it will pull?" and I said "310 hp if I'm luck..." He was SHOCKED... Had fully expected me to say "Oh 375HP at the wheels for sure..." It turned 296whp and 301#ft. torque.

 

After some LGM headers, hi flowing exhaust and new cats, and an LS6 intake w/Shaner ported Tbody, the car laid down 335WHP and 353#ft. torque on a very modest track day friendly tune. The car made over 250#ft. torque off idle. and it was a simple joy to drive at the track. The Z06's wouldn't walk me if I had a head of steam coming out of the corners...

 

After the heads and cam motor went in, I had Jeff tune it at his shop and we went from a baseline of 358WHP and 364#ft. torque to 374.5 and 369.7, so I rounded up to 375WHP and 370#ft. torque. The car came alive and I felt the power everywhere... The new cam brought the torque out at a different place, changing the characteristics of the ride, but making it like a sledge hammer as by 2000RPMs the torque was there at over 300#ft...

 

Now here is why it is important to understand why it is so important to tune your car... After a simple change of MUFFLERS from Borlas to Z06 mufflers, my car was running pig rich and had to be retuned. At the next Dyno day at Jeff's shop, We retuned the fuel and picked up 11whp and 10#ft. of torque... ON MUFFLERS!

 

Mike

[stinky]

That's correct. Afr's where 12ish, timing was 22deg, boost was well into the 20psi range before I could get the mass airflow reading that I ran on the street the day before at 20psi. Not sure it was because of the dyno or heat in the dyno cell or what, either way I drove away from the dyno and it would ping at the same psi. What would/could have been the problem?

 

Was this on the Mustang dyno you went to? Here's my guess. I think you mentioned that the dyno operator entered in a a lower weight than what your car actually weighs. That being the case it would have thrown off the ramp rate to something much faster than what you would see on the road. Is it possible this faster ramp rate would have allowed things to happen too fast so that the engine/ic/other components didnt heat up as much as they would have with a slower ramp rate? This would allow for more timing and less fuel with no detonation.

 

Now this question goes to the Zensport and other tuners. Had they tuned his igntion/fuel by doing steady state load I assume this would not be a problem. In fact wouldnt steady state tuning heat the components more than might happen on the street and result in a safer tune?

[Bernardd]

Stinky, that is correct on the Mustang dyno and weight of the car.

 

Drax, there was absolutely no detonation. It was very quiet in the dyno room compared to in the car. There's no way I could hear it in the car and not in the dyno room.

 

What the actual #'s are don't matter to me. The fact that I couldn't run the tune made on the dyno while on the street matters to me. Others have contacted me to say they've had the same experience. Now is it the nature of a dyno or the operator or......????

[Drax240z]

I'd say it's a bit of both. Mostly the operator and his ramp rates, but I'm under the impression that with most machines it is quite easy to put more load on the car than you can on the steet. (I certainly can)

 

For example, when set what I refer to as the "ramp rate", I can choose anything from 1.0km/h/s to more than 20.0km/h/sec. What this means is how fast the dyno will allow the car to accellerate at a given load. (usually full throttle!) As you can imagine if I was to set my ramp rate to 1.0km/h/s and do a pull in 4th gear at full load, that would be EXTREMELY high load, and way beyond what most cars could ever do. That's simulating a hill so steep that your Z (or whichever car) will only accelerate 1km/h every second, at full throttle in 4th gear...

 

To put it another way, imagine a hill so steep that your car has a 0-60mph time of somewhere around 2 minutes. Like I said, more load than you can ever see on the street.

 

So I would attribute your problem to the operator, though he may not be aware there is a problem. Often you'll go with your gut instincts for ramp rate, and sometimes they are just wrong. Let him know what's happening, and he should be able to ensure it doesn't happen again. (and maybe he'll throw in a cheap/free retune) Faster ramp rates are used for more powerful cars, lower ramp rates for slower cars... they should simulate worst case road conditions to be ultimately safe on the street.

 

I guess the answer to both the last 2 posts is that it depends how the operator is loading the car.

[olie05]

So, theoretically, one could extract a good ramp rate approximation from a timeslip. For example,

My car runs the 1/4 in 14.8s, at 90.8mph, and the 1/8 at 9.5s and 74mph

 

since the car is under more load for the second half of the quarter mile,

 

90.8 - 74 = 16.8mph

 

14.8 - 9.5 = 5.3s

 

appx ramp rate = 16.8/5.3 = 3.17m/h/s ~ 5.10k/h/s

 

Does that ramp rate sound right for an average "sporty" car?

 

also, would I be able to go up to any dyno tuner and say, "i want you to use this ramp rate?"

[Drax240z]

Awesome post Olie! I had never thought of using 1/4 and 1/8 mile times to approximate ramp rate, but it's a brilliant idea. (too bad we have no strips around here!)

 

I cannot speak for other dyno's as to how they determine the ramp rate. It sounds like Mustang dyno's use weight, rather than an acceleration rate. But for a DD dyno you could just give them that number and away they go.

[DCZ]

Good questions for sure:

 

1. Cooling: I have 3 (yes' date=' three) 14,000 CFM industrial fans at my shop, that move some serious air. A total of 42,000CFM if required. If your dyno facility doesn't take their fan situation seriously, you should be alarmed. A household fan is not sufficient! (don't laugh, I've seen it) Small squirrel cage fans that move a decent amount of air at a high velocity seem to work pretty well too. A rule of thumb, if it looks like your facility has spent less than $500 on fans, they are not serious about keeping your car cool.

[/quote']

HAHA Drax - Timely post. I noticed a new dyno (DynoJet) in town and stopped by to check out his operation. First thing I saw was a tiny 16 inch household fan sitting on the floor in front of the car! Don't think I'll be taking my car there!

[stinky]

This seems to be a very common problem. We had a track event where a portable dyno showed up. They had a big fancy trailer with fold up sides, lcd screens to display graphs, and a printer to print out your graph. The only fan they had was a small 12"? blower that sat to the side of the car. Oh, and it was a dynojet. I think most customers just dont think about what affect the heat is having on their car.

[Drax240z]

I think part of the problem is most higher end dyno's actually come with a fan, mine came with 1 of the 14,000cfm fans. I believe the cheaper inertia dynos just come bare bones to keep the price down, and people don't really budget for the secondary equipment needed.

 

Though in reality I got one of my fans used from an equipment rental place for $200, and a 2nd new one for $300... It's not a massive amount of money.

[randy 77zt]

a turbo car with intercooler would need a huge fan to get a good dyno number.dynojets are popping up like crazy around here.but going to the cheap guy close to home probably will waste your money.

[BLOZ UP]

hey Drax240z,

 

I have a couple questions.

 

Is it better to dyno turbo/supercharged cars, displaying uncorrected values rather than SAE/Standard/whatever? I had a guy come in and say that it's better to not compensate for air temp, etc. on a turbo car...

 

I can see getting more consistent results from dyno to dyno... but isn't that also *not* what the car is actually making?

 

Also, have you ever experimented with tire pressure?... I am still not entirely sure how, but I had a ls1 powered truck come in with low tire pressure on both rear wheels (20 or so psi), we raised it to 35, and gained 40hp over almost the entire range... maybe it had to do more with wheel diameter affected engine rotations per drum rotation, and not actually "giving" the car power...?

[Nismo280zEd]

but I had a ls1 powered truck come in with low tire pressure (20 or so psi)' date=' we raised it to 35, and gained 40hp over almost the entire range... [/quote']

 

I knew those ricers were on to something!! So fresh air in your tires DOES give you more HP!!!!

 

lol j/k I couldn't resist.

-Ed

[Drax240z]

We do not use air temp compensation for turbocharged vehicles... by the time you get the air from the filter (where you place the thermocouple) to the TB on a turbo car the temp has changed so much that you aren't really helping your cause at all.

 

We bump up the tire pressure to maximum rated for the tires too. The smaller contact area of the tire tends to have it deform more, leading to greater losses at low pressure. By bumping up the pressure we keep the deformation, as well as heat and hp loss, to a minimum.

[Dragonfly]

I've learned alot from reading this post and one of the things that I knew was possible but did not know how it worked was how the operator can force a car to read higher or lower numbers. I was at racelegal when a local shop brought their Mustang dyno to the track, they were charging $50 for three pulls on the dyno then they would give you a printout and some advice... I decided that I would go ahead and put my car on the dyno and see what I was putting down. The first thing I noticed was after the car was all strapped down and ready for the first pull they had not come up with a fan anywhere, I asked about a fan and the operator told me there was cool air outside at night that fans were not nesissary (sp) I knew that was bs but I had already paid my money, was strapped down and all my buddies were waiting for the results. So I went ahead and did my first pull which the operator told me would be a 1/4 mile run using the dyno and I should drive the car as if I were drag racing. After doing that he asked if I thought the 1/4 mile time was what I thought it should be (it was 13.xx) and I said probably so he told me we were going to do a pull for numbers now that the dyno was set for my car. The operator did a few things on the computer then told me how he wanted me to bring the car up, I followed his instructions and as I was making the pull I noticed that in 4th gear I stopped accelerating at about 4500 rpm even though my cam is supposed to make power through 6000 rpm after 3 to 5 seconds of my engine lugging at 4500 rpm and my temp nearly going off the scale I shut it down and refused to do the third pull. The operator gave me a printout that said I had 155 peak hp and 157 peak tq then he told me that my car had alot of problems and if I brought it into his shop that within 8 hours of dyno tuning they could gaurantee (sp) me at least 50 hp and tq gains. I knew that was a full blown load of bs and that they were just going to adjust the dyno to show me what they promised. I did not know until now how they actualy did it I just knew they could.

 

I have ever since that time told anybody and everybody that ever mentioned there shop to avoid them because they are ripoff artist. I am glad there are people like Drax out there that want things done right and is honest about what he does. BTW I run the 1/8 mile in 8.7x seconds at 79.xx mph and my car weighs about 2565 lbs with me in it. I am not sure how to translate that to hp but I bet its more than 155.

 

Dragonfly

[Drax240z]

8 hours is a HUGE amount of time on a dyno for 1 car, if it's a load control dyno. Unless you are setting up a full stand alone from scratch on a car that needs every ounce of power out of it, 8 hours is robbery. 3-4 tops on a good dyno with a competant tuner.

 

You could probably get away fine without a fan on a baseline, 4th gear pull. (I've never tried without a fan honestly, it's 15 seconds work to add the fan, and both the customer and I are happier with it there) 1/4 mile though is really excessive without a fan. Not cool. (pun!)

 

Another reason I recommend DD units is the training that goes with the purchase of the unit. Yet another reason why it costs so much more as well.

[Dragonfly]

I figured out real quick that he wanted to rip me off. I think he wa hoping that I was a little more gullable than I actualy am. My setup is pretty straight forward and could probably be done in a fairly reasonable time frame I just have to do some research to find someone that I feel I can trust for doing the dyno tuning.

 

Thanks again for starting this post and putting some real information out here for us to read and for proving that there are still some honest people out there.

 

Dragonfly