dynojet 248x

[JustinRaney]

How good is a dynojet 248x compared to others? Im going to have my car dynoed on that dynojet with wideband o2 logs to confirm my current tune is correct and the afr is where its supposed to be. 12.7 max afr is where you want the car at for max power correct? 12.9-13 or above is way too lean of a tune to keep driving with? Its 75$ for 2 pulls with wideband o2 on the dynojet 248x to confirm my afr is correct and get some real dyno graph numbers. Car runs great but i have another thread where it was dynoed on a dynocom 5000 and ben charles mentioned it looked lean as power dropped off at 4250rpms vs a steady incline slight decline 6k-6500K as all other ls1 dynos i have seen.

[The Black Sheep]

DynoJet 248 has been around at least 15+ years and are pretty well established for being good dynos, any decently maintained 248 will give you solid numbers. There is no one AFR for max power, that's why we test different AFRs on the dyno. 12.9-13 will work with some setups, nothing wrong with it as long as the car is happy. Not enough info about your car to know why it's falling off at 4250 rpm, post a log of the run if you have one.

[2xLS1]

Dynojet 248x is strictly an inertia dyno. Dynojet has come out with load cells that can be added to their 24 inch diameter drum inertia dynos but I don't think they offered it for their 48 inch drum dynos. I could be wrong on that as I've not looked into it in a while. You are spinning up two weighted drums and the software measures the rate of acceleration and backwards calculates a torque value with a fudge factor. (that is a quote directly from Dynojet) So basically a WOT dyno. There was a way to use the dyno brake to simulate a part throttle load but I don't know any shop with a 248 that ever used it because I think it was hard on the brake. True dynos actually measure torque with a load cell and calculate HP with the formula HP=Tq*RPM/5252.

[JustinRaney]

Ah so is it possible for 12.9-13 to be good afr whats lean and where it would tear up an engine eventually?
My car is 99 c5 corvette auto 3.15 stock trans converter, tsp headers, stock h-pipe 2.5" straight pipes, volant 5123 oval air filter, elgin 1839 cam 220/224 112lsa 286/282 .575 lift tsp 7.4 pushrods and pac 1219 springs. The car runs good just other shops told me they normally incline to 6k and my experience with a smaller bullit cam manley double springs was the same on mustang dyno peak 6k-6600rpm. The straight pipes are after the tune was with stock mufflers. Tuner told me hed run it on dyno see where it makes power and left it at 6k shift points tuned 12.6-12.7 afr. Said it looked normal already had just about everything. think its just a strange dyno someone else told me they had the same dyno and when the torque reads high like that they either strapped the tires down sideways on the dyno or not even.

he had told me he dragged the graph over to 5500 or something because he didnt want to go above 140mph on dyno but was tuned for 6k.

Another shop with a dynojet 248x said i could do two pulls with afr logging to confirm fueling is correct as i dont have a wideband just yet for 75$

[Alvin]

That big lump in torque looks like it spun on the dyno. A car with a loose converter will also do the same thing.

What ever AFR makes the most power that can be backed up several times with no knock will be safe for the engine. Typically no leaner than 13.2 but every car is different and no wideband/placment is 100%perfect.

The cam would likely peak at 6000RPM a 6400 RPM shift point would be appropriate.

[JustinRaney]

Its stock converter 3.15 gears. so 13.2 afr is the max before would consider it lean. I was expecting power to 6k as well. It may be worth the 75$ to have two pulls on the other shops dynojet with afr logging. The car runs good just the graph is way different then a mustang or dynojet.

I maybe should have went with mail order tune but had the funds for a local dynotune. It was 450$ but for injectors would require a whole different tune which is 450$ as well not the half price but full funded retune. Small things like gear change can be done for free. Should have asked before having it tuned. I may purchase a glowshift wideband so nothing above 13.2 is fine WOT.

[Alvin]

I've honestly had nothing but problems with glowshift widebands. They often read half a point different than everything else.

[JustinRaney]

Can you recommend a good wideband. Those look nice ive read bad things about the the innovate lc2 o2 sensor connector not plugging incorrectly so i decided not to get the innovate lc2 and i guess no glowshift. What widebands have you had good experience with? I used the aem 4110 in 2011 on my 98 z28 turbo tuned by lsxdyno and stayed 11.7 afr with 6lbs s475 501whp on the stock motor and it worked good but i dont really like the look of them to this date. Whats a good wideband? I had to sell my turbo turbo z28 i had a stage 2 6 speed trans and parted out the motor i never got to use forged 347 compstar h-beams, wiseco flat tops, 317s, lunati 232/238 cam i was planning on running 800hp with for a family emergency. But yes on to the other subject the dynojet graph should look similar to this mustang dyno not sure why the dynocom5000 does that and what widebands have you had good experience?

Is it possible for him to have dragged the dynocom graph over 500-1000 rpms or is that not possible before printing me one as i had asked after having it dynotuned 2 months ago?

[JustinRaney]

By half a point you mean .5 off? 14.5 vs 14.0 or 14.05 vs 14.00 within accuracy? Autometer has one but they are old gauges not sure how good their widebands are.
https://www.jegs.com/i/Auto-Meter/105/8079/10002/-1 and the ngk is close to 292$ NGK Powerdex AFX Air/Fuel Monitors

These two look nice any problems with the msd or autometer or not enough experience these are about 240$-260$ Are you suggesting an aem x series or 4110?

[The Black Sheep]

I use an AEM 30-0300 and it's held up really well for the past 2 years I've had it. Did the tuner run the car with the converter locked?

DynoJet 248's did come with optional load control using the air brake instead of eddy brakes. Never saw the long term effect of it, but I imagine it required replacing the brakes a lot sooner. The most accurate dyno is an inertia dyno because it always knows the weight of the drum whereas load cell dynos need to be calibrated periodically.

[Alvin]

I've had the most consistent results by far with AEM wideband.

[kingtal0n]

A dynojet will give consistent results, no tricks or hidden math stuff

AEM wideband is the best wideband for the price available

If you do use dynojet, make sure to get a graph with SMOOTHING=0 For diagnostic purposes

Most engines Natural aspiration best output could be 11.9 to 12.6:1 rarely leaner or richer than that
I like 12.2 to 12.4

[JustinRaney]

So aem wideband is the best? I really like the look of the autometer carbon fiber digital gauge. I plan on single round poding it on the dash just above the steering wheel so i need something thats good to look at while driving and not just for wideband purposes. Tho the shop can confirm afr WOT when doing 2 dynojet pulls.

Now with that being said at anypoint in time if the car was running rich or lean due to bad injectors wouldnt it throw a lean code or whichever? The c5s supposedly have these type of computer diagnosis?

[kingtal0n]

Well. Using the physical gauge to full ability requires years of experience.

The way most use wideband properly is data logging it, over a long period of time collect data, re-tune, collect more data, re-tune, more driving, collect more data, etc.... forever. This is done using data logger. Very few people can actually make practical use of the gauge itself. I recommend hiding the gauge.

[JustinRaney]

Well i have a dyno appointment tomorrow at a different shop for 2 pulls with dynojet 248 with wideband AFR for 75$. Hopefully all works out well and no catastrophic engine failure.So 12.2-13 afr should be good for WOT. I've driven the car as a daily driver and changed from the stock 275/40/18 hankooks 26.7" to c5 z06 rear rims with bridgestone 295/35/18 26.1" rims in the rear. Im wondering if its possible to put on a set of refurbished 243 heads and not having to retune and the car be closer to a z06. At that point may as well swap to some green giant 80$ injectors 42lb-48lb 58psi fuel pressure as my injector duty cycle is at 96%. Ive ran 42lb to 501whp on a 6 speed car at 120% duty cycle and the car stayed at 11.7afr WOT with 6lbs of boost. Someone had asked me if gearing alter hp/tq numbers on the dyno? Would anyone happen know if auto 3.15s swapped to 3.42s or 3.73s would alter horsepower/torque numbers and by how much? If the dyno comes back good with correct AFR there would be no reason to throw a wideband in there unless there was nitrous kit added and needed to check correct AFR. Im only running 25 degrees of timing on a dynotuned 99 stock auto, 3.15 gear corvette with tsp headers, volant air filter and the elgin 220/224 112 cam and stock 2.5" exhaust with a better flowing rear muffler setup. I read in a corvette mod magazine that tsp headers added 21whp 26ftlbs of torque and that the open lid air filter mod or i suppose i better flowing air filter volant oval filter added a solid 15whp and whatever the mild cam adds.

So yes should report back tomorrow if all else goes well with the dyno tests. Ive since added a better flowing muffler set up and the 26" rear z06 wheels.

https://youtu.be/o2cDaiShD0Y

https://youtu.be/tLp0nZ2Ao2U

[JustinRaney]

Got the car on the dynojet with wideband said 12.5 afr and 13afr tops which was good these numbers look to be more correct. 349whp 351wtq 99 c5 auto 3.15 tsp headers, 2.5" stock exhaust better mufflers, elgin 220/224 .575 lift cam and volant oval air filter. I think it could use an UD pulley and ls6 intake for 15-20hp. So if afr checked out correct 12.5 then there would be no need for a wideband.

[JustinRaney]

https://youtu.be/3Q-kQQbkab0

https://youtu.be/2iKCbXZZF78

[kingtal0n]

Dyno wideband tends to read a couple points leaner than in car wideband. 12.5 at the dyno might read 12.8 in the car.

Wideband will pay for itself in the long run because eventually you will need it for something, even just to diagnose a sensor failure.

Looks like a strong motor, good curve, but always get smoothing=0 data for diagnostic purposes, the smoothing=5 is just for showing off a pretty smooth curve, some useful data is in the curve was averaged out by the smoothing.

[Ben Charles]

I don’t trust a tailpipe sniffer, shops that do that are just lazy… put the WB in the exhaust.

I still stand by my initial review of your program that it’s little lean… don’t target 12.8-13.0 AFR on gas engines, everything has ethanol in the fuel so “AFR” readings need to be adjusted for this.

[2xLS1]

everything has ethanol in the fuel

Not in Oklahoma.