Well I spent my lunch hour at the dyno trying to get a baseline run for the stock engine. As expected following HDDP's experiences I ran in to ECU/ESP/TC issues preventing a full run. Despite this I was quite happy with the results, because I now know that motor is pretty well up to spec and I know what I need to do to progress.

Full(ish) story on my site: here

 

Nice try. What is it going to take to get a full dyno test on the Crossfire?

 

Hopefully my ABS sensor widget will sort it. I am going to try it out this weekend.

 

Just an update on solving the dyno issue...

I think I have a far simpler solution than building a widget to feed a signal into the ABS. I am going to do a mod to feed the rear wheel speed sensor signals into the front wheel sensor inputs. I don't know why I didn't think of this earlier, Doh!

 

My question is, what would happen with the ECU if the rear wheel diameter was the same size as the front wheels or vise versa? Would this trip a code in the computer and screw up hp output?

 

great idea, hope it works, but I can't imagine your ABS will work properly. guess you can always restore the front sensors after dyno runs.

 

That's a valid question. I don't think it is a major issue though as the ECU has to allow a big differential between wheel speeds in normal driving conditions anyway.
Yes, the mod will only be a temporary 'fix' for dyno runs, so it won't matter if the ABS isn't working. I am going to try another dyno run this week if I can get a slot booked.

 

Simon: A real head scratcher... I was starting to think we did something wrong when the car crapped-out at 5,075 rpm. I hope you can get an answer on this problem and we can both make full rpm runs.

This is good, now we have comparative dyno's that represent a completely stock car and one with some mods. I'll have to convert your torque #'s from Nm to Ft lbs though.

I've attached a photo of my dyno print-out including FAM #'s so you can compare. It seems we are reaching max hp & torque at about the same rpm, though the #'s are a bit different.

It's quite interesting... Though we have runs at nearly 20 degree different temps, you are showing slightly higher torque and I'm showing much higher HP at nearly identical RPM.

Did you get a FAM measurement ?

 

Wheels don't have any effect on the HP reading of a dyno, you may show some difference on your speedo at the same rpm though. I'm running 18's both front and rear.

 

Looks like your putting down about 200 hp to the ground, what mods did you make? and how much does your autox car weigh?

 

so hddp is putting down 29 rwhp more to the wheels than woody. i guess its safe to say his mods help and the chips must be a big part of that. can you remind me what all your engine mods are again hddp? are you still running that saskins intake?

 

Perhaps you mis-read the dyno... max whp is 186 @ 4,785 rpm, torque is 211 ft lbs @ 4,277 rpm.

#431 is not for Auto X. My venue of choice is full road course racing with the national auto sports association. based on the last weigh-in, I have the car down to 2,680 lbs from the OEM weight of 3,000 +.

Calculating HP/WT ratio, the car is running .0649 hp per lb, vs. the stock car at .052

My modifications can be found on the forum in great detail.

 

There are some determining factors in this comparison with Woody. First off, he was 20 degrees hotter ambient temp. Also, I was running 91 octane pump gas, instead of the 93 octane recommended by powerchip. Which is far below the 100 octane I run at the track.

Yes, I am still using the dual intake and had the Powerchip Gold 93 installed last year. But if you look at the fuel air ratio figures, I'm running VERY lean for some reason. Once Woody and I figure out how to tackle this problem
(which could be a result of removing my cats, or the powerchip), I could goose another couple of hp out of the car.

still lots of work to do...

 

We did log AF and a load of other OBD stuff during the runs but in the limited time I had we were mainly focusing on getting a full range run. I will have a word with Gordon and see if I can get a copy of the data off his PC.

The comparison is very interesting like you say. All the indications are that I am bang on the stock 215 HP (running pump 95 RON). which would suggest that the AF is pretty close to ideal. Interestingly the power was the same even running an open intake on the second run, so I think most of your gains are coming from the exhaust, chip, and, as Intenseblu pointed out in an earlier post, the lean mixture. Of course the intake may be playing a part with the less restrictive exhaust.
As I am sure you'll agree I think it is far too early for people to start speculating on which mods are doing what. After all we only have about 4 runs between us (incomplete ones at that) 1,000's of miles apart, on different dynos, different conditions, and one car that we know for a fact isn't running at it's best. This really is just the start.

On the dyno front...
I did some more tests this evening on the speed sensor mods. and managed to recreate the 5,000 rpm limit by disconnecting the front speed sensors. I replaced them with 15K resistors but the ECU was still showing an ABS fault when I fired up again. I then found that the system needs to see all four wheel signals above 15 mph before it will clear the fault. My test was at standstill, so I need to have another go at it once I have a proper break-out connection on the CAB. Oh, and the pin-outs for the CAB connector in the Service manual are WRONG! I'll do a proper update on progress on my website later and hope to have this problem licked by the weekend!

 

I'm very curious about your AF ratio since it would be a good indicator if a 7th injector would be of value with this powerchip, which seems to be leaning out my car, or this is how they are achieving their alleged hp gains.

I agree. The enlightening part is that our peaks are occurring at nearly identical rpm's, which leads me to believe at least the different dyno's are functioning similarly. It is way too early to pinpoint a reason for the hp difference, for all we know it could be the 20 degree temp difference !

I'm still leery about the powerchip claims...

Gee whiz, are you surprised ?

All in all, good job mate... You've just sparked my interest again...

CHEERS

 

What kind of dyno are your running - inertial or absorption?

HDDP - wheel/tire size could make a difference on a dyno - depends on whether or not car specific data was incorporated or not. Changing wheel size is like running in a different gear and not telling the machine. A Dynojet is supposed to account for which ever gear ratio you make a run in - but it does not do it in the real world.

What kind of O2 sensor does the crossfire have? A nertz or wideband?

We've done quite a bit of testing on a Dynojet here in town (mostly Miatas), and we are in the process of building an engine dyno (Stuska) - but that little project is sort of on the back burner.

Cheers

Henry

 

Hi Henry,

The dyno I was using is a MAHA LPS3000 which I am told is highly regarded throughout Europe and is approved by Audi and Porsche, although I have been told some people don't like them because they tend not to give 'impressive' HP figures. I think the runs were in 4th gear from memory, but I am not reading too much into the numbers until we manage to get a full redline run.

 

Mine was done on a Dyno Dynamics system, the gear ratio did not get logged into the system before the runs, but we ran the car in 4th gear which is the closest 1:1 gear for this car. Also I run 18" rear wheels.

 

From the information on the site that Woody gave the link for, it appears that the MAHA is an absorption type - these do tend to give lower numbers than an inertial type.

From my OJT experience, the inertial dynos use a drum of known mass. The vehicle accelerates the drum and the time it takes is monitored via microprocessors, equations applied, and voila, torque & HP numbers appear. DynoJet is a common unit of this sort. the absorption type use some sort of variable load (electric, water, etc) so the engine can be tested at a given rpm. The Mustang dyno is fairly common over here in the US, and it too produces lower (some say more accurate) numbers then the DynoJet.

I'm not familiar with the Dyno Dynamics either, but from their website, it appears to be an absorption type as they talk about holding rpm constant - which you can't do with an inertial unit.

Obviously, the biggest thing is using the same one for back to back comparison of changes.

Unfortunately, all of the cars I have experience with do not have as complicated an ABS system as the xfire does (both Miata & SHO ABS didn't bat an eye when one end of the thing was going 130 & the other zero). As I intend to modify my crossfire at some point, I am very interested in how the rear signal feed to the front sensors works out.

Henry

 

Thanks for the heads up on the dynos Henry. I spent some time today tapping into the ABS sensor signals. It looks like it is not going to be quite as simple as just feeding the rear wheel signal directly in to the fronts as this seems to causes problem with the ECU looking for open and short sensors. I think I just need knock up a small circuit to derive two independent front wheel signals from a rear wheel sensor. I hope to do this tomorrow and do a full write up on my site when I have it figured out.