2nd round of dyno runs

[briann510]

spent a couple hours on the dyno this afternoon and ended up with a best run by going from 175 to 162.5 main jets and made 10 more RWHP from previous 215 to a 225. was gonna drop down the air jets from 210's to 190's and then couldnt find 6 of them to do the change we wanted to try.

 

the test run info was with air cleaners on, the base run info was velocity stacks only. with air cleaners on we lost about 1.2 hp, but i can attribute that to the 50mm stacks too close to air cleaner tops.

 

still have some figuring out whats causing the 2800-3800 rich a/f ratio drop to 10.40 (probably acc nozzles, but just not sure just yet, or if the mains cutting in at 3K arethe problem and too little timing). have another drop at around 4800-6000 but its still staying in the 12.50 range so its fine for now.

 

so with a 20 percent corrected mustang dyno machine to a dynojet machine number comparison its now 270 RWHP for those of you that are into the numbers thing and not just tuning info.

 

we havnt made any runs with racing gas and timing changes from its 31 degrees total. we are trying to see what it will do strictly on 91 octane pump gas. i would guess bumping timing up to 34-35 might gain a few extra horses, but not worth it for the extra cost of racing gas.

 

so the current carb info is:

162.5 main jets

210 air correction jets

67.5 pilot jets

50 acc nozzles

44mm chokes

 

[COZY Z COLE]

 

so with a 20 percent corrected mustang dyno machine to a dynojet machine number comparison its now 270 RWHP for those of you that are into the numbers thing and not just tuning info.

 

 

Your comment has me a little confused. I noticed that you started your other thread on the first dyno session witha a dynojet comment. I have 30 dynojet runs on my car and not one of them was for "numbers" and all of them were certainly for tuning perposes. The dynojet shop in my area is the only chassis dyno for miles around. In the 2 years I used it I've seen from racing teams to individuals use this shop and not one was spending their money to get "numbers". They had spent serious money on mods and wanted a well tuned machine. Now all that said keep up the good work.

 

LARRY

[briann510]

there is currently no dynojet facility within 30 miles of my house, and the mustang dyno is 2 blocks away. i just found a place that is having a new dynojet delivered as they got rid of their old one that is 10 miles away, and they told me in a week they will be taking customers.

 

i made the comment about bragging numbers vs tuning numbers because alot of people around here just go to the dyno to get rwhp numbers and thats it. they dont tune or make any adjustments.

[Drax240z]

Personally I don't like dynojet as much as the other options out there. They read notorously high for hp, fine for comparison purposes, but really just an ego boost for said owner. Also the base model (which many companies buy) doesn't have any kind of load control, which honestly is the only way to tune with a dyno. Doing pulls through the rev range and getting your AFR is nice and all, but it's not a very useful tuning aid, you might as well just buy a wideband with datalogger. (not to say these aren't useful, I just wouldn't want to spend a minimum of $25k US for a dynojet and not be able to tune accurately) If the purchaser springs for the extra's with the dynojet (load control, wideband, etc) it brings it up to the level of most of the other dyno's on the market.

 

For me, I want to be able to tune. I don't care about HP numbers. Which is why I am trying to buy a dyno dynamics setup for my shop. I can hold RPM and LOAD anywhere I want. I can simulate going up a hill at 4000rpm in 4th gear, then at 4250rpm, then at 4500rpm, and hold it there while I do my tuning for that specific cell. I can hold it there and play with my timing to see how much power I gain or lose at that specific rpm, in real time. It might cost twice as much as a dynojet, but I think the results will be well worth it in my customers eyes. And if all they care about is hp numbers, then we can do that too.

 

However, as long as you use the same dyno back to back, and if you are comparing mods done to your car to see the results, any dyno will help you there.

[JMortensen]

Your A/F ratios look pretty damn good to me. The A/F ratio drops to 10 because the velocity of the air goes to really low when you open the throttle plates, and at the same time the accelerator pumps dump a big pee stream of fuel into the cylinders that doesn't atomize and burn very well. This is what I was trying to explain in your last thread about the off idle stumble. When you don't have any velocity in the intake and you just slap the throttle plates open it's going to stumble because the engine looses most of its vacuum on the intake side until the engine speeds up and the velocity increases. I think you'll find that it runs stronger and pulls through that part of the rpm range better at 10:1 than it will with smaller pump nozzles. Again, this is where smaller chokes would benefit you (at the expense of top end). As far as chokes go, did you take them out? 44mm chokes would be... invisible...

[briann510]

well, the engine screams now. it looks like something we just have to live with as its running really good and the dyno runs look good. i dont think the engine will make anymore power, so we are fine with it with current jetting. it is definatly the acc nozzles, as when we started with 35's it had a horrible stumble and really cleaned up with the 50's. i dont know if trying 1 more change on the nozzles will help anymore or not.

[Guest bastaad525]

*sigh* why do people keep saying how Dynojets read high all the damn time. You need to say specifically, what they read high compared TO, when you say that, otherwise you are misleading people. True, they do tend to read higher than some other popular dyno models (Dynapack, Mustang), which is pretty common knowledge by now, but they also seem to be fairly consistent, from dyno to dyno, and compared to factory rated numbers on factory stock cars.

 

Also, most people, when asked, will say (in general, not thinking of any particular type of dyno) that your flywheel hp should be around 15% more than the HP measured to the rear wheels. IMO, this oppinion seems to be based on testing on a dynojet to begin with. I have seen so many published tests, I've seen quite a few friends test, and even strangers who were testing their own cars out before me while I waited my turn in line, on dynojets... testing factory stock cars or barely modded cars, and the dynojets consistently give numbers that were very close if not right on the button, at about 15% less than what the factory rated the car at, in the case of stock cars. There have been a few exceptions, but it's definately more common than not.

 

So if the standard opinion of most people is that dynos tend to give numbers 15% lower than the approximate flywheel number, and Dynojets do pretty consistently give numbers that are right in that area on a known commodity (factory stock car)... how is it that you can say that Dynojets are 'optimistic' or are only good for an ego boost? Seems pretty darn accurate to me.

 

Also, of the friends I've known that have tested on Dynojets and then took their cars to the drag strip, they do always seem to run 1/4 mi. times that are pretty close to what they expected, given the dynojets hp number and the weight of the car. Well... at least this happens for the guys that are more regulars at the track and get a decent amount of practice... when I raced my car (got one and only one run ever) my time was quite a bit lower than my dynojet test had me expecting... but that's my fault for sucking.

 

I hope this statement is making sense as I'm a little tired at the moment. I just get miffed every time I hear someone talk about Dynojet numbers like they are just that useless. Even if it's only to brag or compare to other cars, the numbers a Dynojet gives are NOT useless. With Dynojets being the most popular model Dyno, at least in my area, then what's so wrong with direct comparing one persons results on a dynojet to another? Since most people I've run into have tested on a dynojet, it serves the purpose quite well of giving at least a general idea of who's car has more balls. And before anyone says it... I HAVE tested on three different dynojet setups in three different places and have seen VERY consistent numbers between all three of them... what little variations I saw usually were easily credited to clear, measureable differences, like different ambient temperatures at the time of testing.

 

Also, I know the current thinking for many of you guys is that dynojets are somehow even 'useless' for tuning. Yet last time I went to a dynojet after adding my RRFPR, and did 5 pulls while making little adjustments to my fuel pressure and rate of gain, I very clearly and easily saw differences in both the a/f ratio curve and the torque/power curves as I made little changes, and was easily able to find the optimum tune of the FPR. I can't say anything about the load control, as even when I've tuned on other types of dyno's (I've tuned on both a Mustang and on a Dynapack) this option was never offered to me. I think the ability to tune at specific loads and RPMS is useless to anyone who doesn't have a fully programmable aftermarket EFI setup... which seems to me to still be the majority of us here. I agree though that tuning on a dynojet or any dyno w/o a wideband O2 is kinda useless. But every dynojet I've tested on has had a W/B sensor setup to use.

 

Stop knocking Dynojets guys, please. Lots of people use them, lots of people like them, and the evidence I've seen with my own eyes says they are a LOT more accurate and not nearly as 'optimistic' as some of you claim.

[briann510]

actually what you said makes perfect sense. i wasnt dissing dynojets at all above. all i was saying the majority of the street racer crowd and alot of track guys around here just run a dyno run to get a rwhp number and not to do any tuning from the runs, and with that in mind quite a few people asked why our rear wheel hp numbers were a bit low as they didnt even know there were different kinds of dynos out there. now if someone asks me i just tell them flywheel hp and be done with it.

 

we specifically used the 4 hours of dyno runs to tune.

[Guest bastaad525]

I was referring more to Drax's comments... we've debated this before.

[Mikelly]

There is a tuner locally to me that has the whole DynoJet system, including load control, and the additional packages to similate real world track environments to tune the car to (John Sealock is his name and his shop, Woodbridge Dynotune is listed in the Dynojet Directory on the website)..... Problem is he is dead slow and hellespensive. If you can find someone who has all the extras with the Dynojet, then I'd go spend a fortune and get it right across the board. The other factor to contemplate is WHO you get to tune the car... I'm using Jeff Creech (Also used by the TRIAD ZCAR Club) at Carolina Motor Masters in Durham, NC. The guy is simply SO GOOD at what he does that he flies across the country to tune cars for a living, and is a guest tuner at a LOT of Dyno Shoot-outs throught the country... You want a guy like that who has experience reading the logs, understanding the data, and making the right changes to your setup.

 

As for Dynojet, Mustang, or Dynopack... It is preference and depends on what you are trying to do... Lots of guys (Me included) like to be able to dispell HP claims in general by stating "With XYZ COmbo MY CAR made 123HP on this day, in these conditions and on this dyno... " this helps quell a lot of BS by NOOBs and idiots in parking lots. Other than that, it proves nothing without the GOOD tuner to back up the numbers... When we recently tuned my Vette on a Dyno in Maryland, we got good numbers for my application... Track Day event usage. I wanted the car tuned to MY specific purposes for road race courses... We would have ended up with completely different numbers, had I wanted to go drag racing instead.

 

Without the proper support software and hardware, a Dyno is really NOT that useful, and I'm kinda in line Drax's comments from an application standpoint. Without the ability to similate the environment you plan to use the car in, your just really guessing... Fun, but so is masturbation... and that is a much cheaper way to screw yourself!

 

Have fun!

Mike

[Guest bastaad525]

Again, these kinds of things apply to people with the ability to fully tune their EFI systems... something that doesn't apply to me or many of us guys running '81-83 turbo motors in our Z's with stock EFI. When you're running a setup that is really tunable like that, then I'm sure it makes a lot more sense to seek out a dyno that can do things like maintaining load and other stuff that a basic Dynojet can't do. For me, when I tune at the dyno I only need to know one thing, is it running rich enough to avoid melting anything, and maintaining a safe fuel curve all the way to redline? Everything else is secondary, and because I only have a few parameters I can tune, and only so much money to spend on the dyno time, so this is all I try to accomplish. A regular old dynojet, w/o all the bells and whistles, with a W/B sensor, works fine for me....

[Silent]

here in kansas city we have two mustang dyno's

we also have 3-4 dynojets

 

i have gone from a dyno jet where my z did a 192 rwhp, to a mustang dyno where it did 162

 

now explain to me why this happened?

 

i got it, the mustang puts more of a load on the car

 

this was all done in ONE day, so the variables were not a factor. exact same tune, same timing advance, everything.

 

there is a difference. also if the weight of the car is put in wrong, on a mustang it will kill the hp and raise tq. played around a bit on a mustang to see what would happen

 

my car weighs 2576 on a cat scale.

mustang has it at 3k lbs

144 hp

225 ft lbs

ummm, nope!

 

 

Brian, i am following your posts here due to me thinking of getting mikuni's here shortly, and you're only .1 liter larger then me on engine size. it's giving me a base line to go off of

[Mikelly]

Make no bones about it, Seting the dyno up, calibrating it, then inputing the data correctly for the given vehicle ALL play into the proper output on the dyno. The data is only as accurate as the input...

 

Bastaad, I hear what you are saying. That setup is VERY limited and all you can hope for is good AFR across the board. Any of you guys doing EFI on THAT turbo setup should really consider going with an alternative to the stock intake and AFM/ TB, and a standalone ECU... I know it is a LOT of coin, but the return is simply 10 fold a better platform for more and more reliable HP!

 

Good Luck!

Mike

[Guest bastaad525]

heh... I don't think there are many of us here who wouldn't just LOVE to put in an aftermarket EFI or even upgrade to the Z31 ECU setup if we could. Come on now....

 

 

Fact is many of us just can't afford it, and really, the stock setup can be made to work well, mine runs great and is pretty quick, and was done for relatively low $$$. When I finally win the Lotto though you can bet the stock stuff will be on the way out.

[briann510]

silent,

 

feel free to email me with any questions on the Mikuni setup. they are very prone to underhood heat and it really effects the way they are tuned. THEY DO NOT LIKE ANY HEAT ON OR NEAR THEM!

 

even a cermaic coated header gives off too much heat for them and you will also need a heat shield or header blanket between the carbs/intake and header.

[Silent]

silent' date='

 

feel free to email me with any questions on the Mikuni setup. they are very prone to underhood heat and it really effects the way they are tuned. THEY DO NOT LIKE ANY HEAT ON OR NEAR THEM!

 

even a cermaic coated header gives off too much heat for them and you will also need a heat shield or header blanket between the carbs/intake and header.[/quote']

 

 

i'll keep that in mind

i'll be sure to contact you when i get ready to do the drastic make over this summer

[randy 77zt]

would like to try a 3.1/3.2 l l28 with high compression,good ported head,cam, a good aftermarkit efi system..the thought of getting rid of all that turbo plumbing sounds good.a friend of mine has a 260 with a 3.1 rebello motor with bored su's-i can pull him close to exit of corner but when his car winds up it pulls hard.i have a 77 with stock 280zxt power.

[Guest bastaad525]

randy - yeah so just turn up the boost and watch him dissapear in your rearview....

 

seriously though... having had a built up N/A motor (2.9L) and now the turbo... there are definately things to like and dislike about both of them, but if going fast is priority, you'll get much faster much easier with that turbo motor....