Strange happenings on the dyno

[Danger_Dorn]

So I ran on the dyno with my car this weekend. I have a rebuilt stock redtop with the t25, 370's, fmic, 62 ecu, 14psi, good clutch. I managed to pull 176 to the wheels on the dyno. To me this sounds low. I did the math (whp/.75) it came out to 234 at the crank? Right or wrong. Also my curve was kind of jumpy. My friend with a stock setup at 8psi pulled exactly the same....and ideas or was he just pulling high?

[Danger_Dorn]

Here is the dyno sheet. 62299

[UnknownGuy]

Yeah I would guess if you were boosting about a bar your car would look a little bit more peaky on the graph apposed to a bone stock SR. 235 sounds about right as for crank hp, but you might want to double check your timing and your intercooler lines for a potential boost leaks.

[jr_ss]

What are your AFR's? 14psi on the T25 and 370's is a recipe for disaster. What dyno was this on as that will effect your numbers as well. Keep in mind a dyno is a tuning tool, they all read different from the next.

[UnknownGuy]

What are your AFR's? 14psi on the T25 and 370's is a recipe for disaster. What dyno was this on as that will effect your numbers as well. Keep in mind a dyno is a tuning tool, they all read different from the next.

True. It seems to me that mobile dynos like dyno packs usually run a little less hp then stationary dynos like Dyno jets. I think its the difference between axle hp and wheel hp.

[Danger_Dorn]

It was on a dynojet. My afr's are 11.9 to 12.2 when wot and full boost. I have NO boost leaks. I charged the system with a compressor and it holds. I just found it weird that my friend running 8 psi bone stock managed to pull the exact same power but with a smoother curve. Any explanation about that?

[Danger_Dorn]

62301

thought I would throw this in here too

[ultimateirving]

It was on a dynojet. My afr's are 11.9 to 12.2 when wot and full boost. I have NO boost leaks. I charged the system with a compressor and it holds. I just found it weird that my friend running 8 psi bone stock managed to pull the exact same power but with a smoother curve. Any explanation about that?

I think it's your dual fpr setup that's giving him the advantage

[Kingtal0n]

Its most likely:

A: your turbocharger
B: your plumbing

could also be
1. boost leaks (aka plumbing)
2. bad ignition timing
3. bad gas


My bet is on the turbo blowing hot air. turn the boost down to 8psi and see what it makes. Then, change it.

[fliprayzin240sx]

I think it's your dual fpr setup that's giving him the advantage

i just noticed that...WTF? :eek3:

[UnknownGuy]

I think it's your dual fpr setup that's giving him the advantage

Isn't two FPR's better then one tho? lol
:ddog:

[ivantheterribl3]

Could be IATs. 14psi is about the limit for a t25 and if its hot out or your intercooler is blocked or otherwise inefficient it could cause low power and a shaky graph like you've got. But if A/F is ok and your butt dyno is satisfied, then i wouldnt worry too much.

[G240]

Do you have a psi/afr graph? It seems low even by dynojet numbers. I have a t25 thread with dyno numbers. It was done on a dyno dynamics but you get the idea.

[OutToWinPAHC]

We advanced my RB256 exhaust gear 1 degree on the dyno.... lost 64hp at the wheels, retarted it 1 picked up 22 over 0 degrees... There is too much to tell based on a dyno sheet.

From electric, to timing to overall condition of parts.

I used to drop fuel pressure at 15psi..... ended up being a oxidized wire to the fuel pump, redid the wiring and retuned for another 100WHP.

So what I am saying here is check everything out, from plumbing to pressure, to cleaning wiring terminations. It all matters

[Croustibat]

a real T25 as found on a ca18det ( other called T25H or T25G are closer to a T28 ) outputs IATS around 150-160°C at 15psi . After going through a big cooling core (admitedly not the better), i had it down to around 60°C.
At that pressuren the turbo is overspinning and has such crappy efficiency it has no flow.

See my point ? you DONT want a [email protected] period.

[kamilitaryman]

I wasn't even aware that such temps develop during compression. That's crazy.

[Danger_Dorn]

Very eye opening guys. Lol yeah I'm not running the dual FPR thing anymore though I was on the dyno. I have drilled out my oem fpr and its now literally an adapter. I will try turning down the boost to 12 or so. A few car friends of mine suggested "Since the dyno curve is so jumpy the ECU might be saying no bitch your running stock powah and pulling timing" Who knows.... I'll try 12psi and let my ecu reset by leaving it unplugged overnight to see what happens.

[Danger_Dorn]

Also is the sr20det 62 ecu self learning? It was suggested to me I should reset my ecu by unplugging the battery overnight to learn my new 12psi boost pressure and related fuel curves

[PoorMans180SX]

What brand front mount do you have? Where are you taking the boost reading from?

Crank horsepower would be 198 considering 15% drivetrain loss, it's nowhere near 25%.

[anthonyr sil8ty]

Nothing strange your shit is stock and slow, why waste Dyno time

[cotbu]

Also is the sr20det 62 ecu self learning? It was suggested to me I should reset my ecu by unplugging the battery overnight to learn my new 12psi boost pressure and related fuel curves

Yes, but it doesn't learn boost like you're suggesting, that would be outside of closed loop, that statement seems funny based on one of your posts. Anyway the ecu will learn sensor voltages, and fuel trims long and short, unplugging the ecu shouldn't clear them, alone. Unless the capacitors are discharged. Use a program like conzult, nds or nistune, 1click and then relearn begins vs overnight or hour's then relearn. Ps I have a really good stock tune that has been oversold, that ill give to you just post you're graph. Oh the graph has to show power and torque, options are boost, egt, and afr

Sent from my Highly Tune Galaxy S3.4!!!

[4x4le]

The only thing that self learns on the factory ecu is tps closed voltage

edit: if the ecu has been unpowered for a while it re learns this the first time it powers back up. This is why it is wise to not put your foot on the throttle before cranking.

This is the common problem people have with lean/jerky under light throttle.

.34 volts is not the magic place to set your tps voltage, that is just where it was from the factory, it can be changed (on accident) at any time.


PS, Dyno jets are junk, your running too much boost for a t25, I have never seen any gains after 12psi on a sr with proper tuning on a t25 and most of the time they actually prefer 10psi. I guess it just depends on the intercooler used.

[Danger_Dorn]

Cotbu: I didnt mean it would learn boost directly I meant would it re-learn my maf voltages, inj pulse, and afr's in order to make a new map? From everything I read I would be able to unplug my battery and let it sit overnight to drain all residual power from the ecu. Then my ecu will have a clean memory and can re-learn my fuel maps....? How incorrect is this? Is there a cheap tuning alternative? I was thinking maybe enthalpy or nistune but I'm still stock everything. FWIW I want to upgrade injectors, maf, ecu and turbo in the near future but aquiring parts overtime when i stumble upon deals.

[4x4le]

Also, the shop did you speed based. They dont know what they are doing..... Dyno jets are bad pieces of equipment because all they do is estimate hp by how fast you accelerate the roller. Then they figure your tq off of your estimated hp. See how this is a flawed practice? Now take a shop that dont understand their equipment even further and they dont let rpm get input into the dyno, tqXrpm/5250=hp. Well lets put it this way, everything in that entire equation is an unkown. Somehow they were able to make up a hp number? Waste of a $30k machine.....
Any shop that know so little about dynos, that they will buy an inertia based dyno most likely dont know much about tuning either, so just keep that in mind if you decide you want them to tune your car.

[4x4le]

Cotbu: I didnt mean it would learn boost directly I meant would it re-learn my maf voltages, inj pulse, and afr's in order to make a new map? From everything I read I would be able to unplug my battery and let it sit overnight to drain all residual power from the ecu. Then my ecu will have a clean memory and can re-learn my fuel maps....? How incorrect is this? Is there a cheap tuning alternative? I was thinking maybe enthalpy or nistune but I'm still stock everything. FWIW I want to upgrade injectors, maf, ecu and turbo in the near future but aquiring parts overtime when i stumble upon deals.

It dont know any of that stuff. Between throttle position and maf voltage (real time) it decides load. Those are the cells in your map left to right and then with the corresponding rpm info that decides the pulsewidth.
The only real other factors are multipliers based on percentages it modifies the pulsewidth from cts or iat.

[cotbu]

Then my ecu will have a clean memory and can re-learn my fuel maps....? How incorrect is this?
have you every watched the wideband on long steady throttle trips (cc), tps and mafs voltages stay steady as well as speed and rpm, the wideband will lean out. I've seen a steady 15.2 afr myself on 301. I believe this to be my long term trims kicking in.
So it won't learn the fuel map it will follow the fuel map and what 4x4le is saying is true the ecu will interpolate when you fall into the invisible cells via tp(cells read 28,32 but your in tp 29) tp load determines which cell to pull from. Im saying the longer you stay in the cells controlled by the ecu via the 02 sensor the more fuel is trimmed for max fuel efficiency. This won't help you make , more power on the dyno, but it will help you with that 10-15mpg thread.
what I mean by learning the sensor voltages is, not every person has the same stored voltages for mafs, and tps closed, this is apparent to me because, I've bought faulty oem z32 mafs based on this premise alone. Once the ecu learns the operating voltage the mafs work flawlessly. all i do is clear self learn. That's probably why isis mafs work for me a lil, lol.
The tps closed voltage can be tricky, unless you have nistune, conzult programs or software that can tell you when the tps is registering closed visually, most people miss it. Usually, i find it's accompanied by an 1100rpm idle, tps showing not closed @.45v.55v.60v(the sweet spot was .445v) but to get the range back I had to clear self learn.
so, apparently they just turn the "idle" down. The ecu hasn't learned to idle because it doesn't know when too. So after restart and warm up, (80c) the idle is still 1100rpm.
I hook up nistune and can see the flag not lit, the flag now says tps idle, it used to say tps closed IIRC.
If your looking for it?

Also I'd like to say some people are removing the coolant lines from the IACV, I recently used clearing self learn for this issue as well. The high uncontrollable idle issue.

The tune i referenced is based on 13psi, for a stock mafs and injectors, it usually nets 220-230 on a dynojet from the Midwest to the east cost.
mafs seems like it's the weak link in my records.

I love nistune should probably check for a new version soon. I'm stopping everything at 450hp or 400ft, WCF. I'm still internally stock minus studs and headgasket now. Nistune can be used on a stock setup, and is a better alternative for someone willing to learn to tune, has a nistune tuner local or used to rom tune.

[ivankol]

make sure pin 105 on your ecu plug is hooked up mine was unhooked and we hit 168whp on a mustang dyno after it was hooked up did 208 on 7 psi fuel pressure control module red with a white stripe

[Danger_Dorn]

I'm still not sure why my friend pulled the exact same power as me at 8psi when I was at 14...? Thanks for all the useful info guys

[G240]

Did he dyno at the same place? Does he have the same setup as you?

[Danger_Dorn]

Hes bone stock with the smic at 8psi. I'm running stock with a fmic, 3" exhaust intake, afpr, and fresh rebuild at 14 psi. We dyno'd the same day on the same dyno only a few cars apart

[4x4le]

Like i said earlier, your boost level is a detrement to hp. 10-12 is all that turbo is going to be beneficial to. If you and your friend took boost readings in your hot pipe your pressure numbers would be vastly different.

But the main thing, the dyno yall used, especially the way they had it setup did not give you ANY data worth analizing. You wouldnt be putting this much thought into this topic if the printer was a 3 year old with a red and blue crayon would you? Because that might as well have been.

Even if a dynojet is setup the way it should be (which this one was not), the way smoothing works constantly "alters" the numbers it should be displaying. If the car is strapped down in a way that it rocks back and fourth like the straps are loose or springy it screws up smoothing. If your suspension squats and releases it screws up the smoothing. If the tires are bouncy ect.

You were given inconclusive data that you probably paid good money for. Sorry, thats a shame, and it was probably a new shop or new to them dyno and they dont know how to use it or dont care and they had a dyno day just to pay the bills.

[Danger_Dorn]

Thanks 4x4. Ill look around here to see about a better shop/dyno. Which dyno's are the good ones? FWIW my dyno run was free lol

[4x4le]

Dyno dynamics
Dynotech
Dynopac

[cotbu]

Don't be afraid to talk to the operator, they should go through a setup before they even make a pull, ask what's that for and why? Also be sweet, if they charge extra for boost or afr readings he/she might toss it in for free.;)

Sent from my Highly Tune Galaxy S3.4!!!

[rc1honda]

How fresh was this rebuild. How was the break in done?

If you went straight to the dyno first thing that's where your problem may be as well. The pistons rings have to seal nice and snug before you see the real power of the motor.

Non fully seated rings and and a inefficient turbo maybe the cause for the low numbers.

[JKTUNING]

The amount of garbage in here about the use of a Dyno Jet is somewhat amusing, but alas I will leave that subject be.

Have you ever tried to verify you ignition timing, by putting the car in "timing mode" and checking to make sure you are within spec?

It is always the little things that will can get you and straight blaming it on the dyno for "inconclusive data", isn't the way you should be looking at this.

If you don't already have one, a Consult cable would be a great investment for this type of situation so you can check and verify what exactly is going on in your system.

[Danger_Dorn]

I do have a consult cable and I use conzult and ecutalk. Usually ecutalk. The motor had a good 3k on it when I took it to the dyno. I'll try to take it again sometime and try out the things in this post. My timing is at 15btdc at idle in timing mode.

[4x4le]

The amount of garbage in here about the use of a Dyno Jet is somewhat amusing, but alas I will leave that subject be.

Have you ever tried to verify you ignition timing, by putting the car in "timing mode" and checking to make sure you are within spec?

It is always the little things that will can get you and straight blaming it on the dyno for "inconclusive data", isn't the way you should be looking at this.

If you don't already have one, a Consult cable would be a great investment for this type of situation so you can check and verify what exactly is going on in your system.

If you want to discuss the uselessness of a dynojet Im down. Even the origonal designer/former owner did an interview with hotrod mag basicially shitting on it. When it came out there was nothing comparable to it but considering the technology of current cars, the precise requirements of tuning fuel injected turbo motors (not carbed n/a motors) and the types of dynos avabiable and their prices, dynojets are not relevant anymore. Anyone taking someones money to tune their engine should know this and if they dont I highly doubt their tuning ability.

[cotbu]

I've heard the dynojet I used was an eddy current dynojet, still reads the highest though, so that's where I get my bragging hp and tq figures from.:cool: I also never tune on a dynojet, but I was told the 442lcx? I used for power pulls, could be used for tuning, I said good to know, lol
I still say you need to use the same dyno at least twice, for power pulls. No debate from me I agree,:D 2¢

Sent from my Highly Tune Galaxy S3.4!!!

[JKTUNING]

If you want to discuss the uselessness of a dynojet Im down. Even the origonal designer/former owner did an interview with hotrod mag basicially shitting on it. When it came out there was nothing comparable to it but considering the technology of current cars, the precise requirements of tuning fuel injected turbo motors (not carbed n/a motors) and the types of dynos avabiable and their prices, dynojets are not relevant anymore. Anyone taking someones money to tune their engine should know this and if they dont I highly doubt their tuning ability.

Like I said, I should leave this topic alone .. but your definition of "relevance" intrigues me.

Btw just to clear up any confusion, I am by no means a Dynojet "fan boy" .. I currently own and operate two in house chassis dynos and neither of them are Dynojets.

[inopsey]

Like I said, I will should leave this topic alone .. but your definition of "relevance" intrigues me.

Btw just to clear up any confusion, I am by no means a Dynojet "fan boy" .. I currently own and operate two in house chassis dynos and neither of them are Dynojets.

this is you leaving the topic alone? lol

[JKTUNING]

this is you leaving the topic alone? lol

I said I "should" leave it alone .. but I am curious.

[Danger_Dorn]

I did a compression test today...118 psi dry with a warm motor on the front 2 cyls. So Idk whats going on. My timing is right. I have a 1.8mm metal hg with arp headstuds. The motor has 3500 miles on it now after its rebuild. Any ideas? Ill try some oil in the cyls tomorrow. If it rises by 10 its bad rings and if not its bad hg/valves. The hg isnt blown from all that I can tell. I left my radiator cap off and saw no bubbles....

[JKTUNING]

I did a compression test today...118 psi dry with a warm motor on the front 2 cyls. So Idk whats going on. My timing is right. I have a 1.8mm metal hg with arp headstuds. The motor has 3500 miles on it now after its rebuild. Any ideas? Ill try some oil in the cyls tomorrow. If it rises by 10 its bad rings and if not its bad hg/valves. The hg isnt blown from all that I can tell. I left my radiator cap off and saw no bubbles....

Did you do the test at WOT?

What were the other two cylinders?

Do you have the resources to do a leak down test? This will show you a bit more than just a compression test alone.

[Danger_Dorn]

I only did the first 2 because they were exactly the same 118. I didnt do them at wot now that I think about it. I just got in and cranked. Idk if anyone does a leakdown test around here.

[Danger_Dorn]

What are my options is my HG being too big is my problem? Full sytem upgrade (turbo, injectors, maf and tune?

[ultimateirving]

If you increased the head gasket thickness without milling the head, you may have lowered the compression ratio

[cotbu]

C'mon do all cylinders, and do it correctly at least. I personally do a 3 fire with timing light, on all cylinders, when I check compression on an sr that comes in, then do a max compression test when I hook the battery to a charger/booster. My 3fire test is always higher than 120psi, but if it's not I'd recommend a leak down screw adding oil to the cylinders before doing other test. If you've just rebuilt the engine maybe light rehone and try a different break in method.

Sent from my Highly Tune Galaxy S3.4!!!

[Danger_Dorn]

Cotbu- What do you mean by a 3 fire test? As far as a break in I took it on the highway and did some 3rd gear - half throttle pulls up to 5k and then let it go into vac back down to 2k a few times then soon after I just gave it hell.

Irving- I blew a hg, then did a rebuild so my head has been milled twice. Also I had the block milled. Would 1.8 mm hg really lower compression that much? idts....

[Danger_Dorn]

Also changing the head gasket is not an option unless its legitimately blown

[4x4le]

He means pull the injector clip on the cyl your checking, pull the coil and plug and put your compression check equipment in. Now start the engine.

[cotbu]

Cotbu- What do you mean by a 3 fire test? As far as a break in I took it on the highway and did some 3rd gear - half throttle pulls up to 5k and then let it go into vac back down to 2k a few times then soon after I just gave it hell. 3 fires from the timing light. Did you check compression before and after break in? How did you know it was ready? By vacuum? If so what's the idle rpm and vac? That's not the best way but if you idle at 750rpm and pull 20inhg I'd say the rings are sealing, for sure.



Sent from my Highly Tune Galaxy S3.4!!!

[Danger_Dorn]

I pull -16 to -18. Busy right now ill post later

[jr_ss]

118psi dry is low, regardless of what anyone says. Now if you have 118 across the board you're better off, but it's still not a good sign.

1.8mm head gasket is going to lower your compression quite a bit and I wouldn't be surprised if your closer to 8:1 vs the designed 8.5:1. How much was your head and block milled? You can calculate your actual compression number if you have those numbers. To fix your issue(I know I read), you need to install a new headgasket of 1.1mm thickness or have the block honed and new rings installed, if your comp numbers vary by 10-15%.

What cams are you running? -18in/hg isn't bad, -16in/hg is on the lower side, but can be affected by cams, which lower your actual vac.

[Danger_Dorn]

Not arguing but I thought 16-18 inhg was pretty good? When I'm cruising and I let of the throttle into vac I get up to 24 inHg. Cams are oem. I did the compression test today with wot and got 135-140ish across the board so thats good. Idk how much they milled but does this compression seem right for a 1.8mm cosworth hg? As I said my head was milled twice and the block once.

[jr_ss]

While -16-18 isn't bad, -16 is still on the lower end of that spectrum. Typically you should be in the -18-21 area of vac especially on stock cams. I'm not saying you need to rebuild as there are other factors that can effect your vac readings.

A healthy motor is in the second vac reading I stated above. A motor with some serious cams will be lower, but that's still considered good vac because of the increase in duration and lift.

[4x4le]

Yes, before you even consider a rebuild, check more than one map gauge, check more than one compression tester, and do a leakdown. A leakdown will point you in the direction of what is causing the low reading, hg, rings, valves ect. If it is rings it wouldnt hurt to run some conventional oil or some break in oil for a bit to try to seat the rings better, it is still a newer engine after all.

[Danger_Dorn]

Ok so update. I did a compression test when my motor was 170 degrees and WOT and got 135 on all 4. I replaced my thermostat the other day and now my car gets into the 190's so Ill give it another go to see if it yields higher numbers. From what I have read a 1.8 mm hg will lower compression from 8.5:1 to about 8.4 or 8.3 right?

[Danger_Dorn]

I also may try to retorque my headstuds since they may have moved during break in. ARP's 90ft lbs is what Ive done before but idk what the shop torqued it to

[AJZax]

RS-Enthalpy flew up to WA state, we dynotuned stock SR, it put 258whp at 14psi on a dynojet at 85F in summer. that's t25, 370s, walbro pump, exhaust, intake, and fmic (cxracing).

The objective of engine break-in is to load the piston-rings to they are pressed against the cylinder wall with pressure as to SEAT. I drove my car 18 miles to the dyno after an initial operating temperature "break-in". During these 18 miles it's all on throttle, engine decel, on throttle, engine decel. Put it on the dyno, and you could see it make more power every pull. FIrst like 270, then 330, then 440whp at 15psi. (SR gt3076r, E85). It was awesome to feel the car make more power as I drove it to the dyno also ^_^

When you first start your car you want to do on throttle, off throttle, first between the 2500-4500, then slowly expand that range, but keep out of 20psi+ hahah. After the idle oil change and the initial drive oil change, slap it on the dyno! :p Either it blows or it boosts!!! lol

[jr_ss]

ARP is 80ft lbs with the moly lube, not 90.

[Danger_Dorn]

Crazy...Idk how I'm only pulling 176whp. I beat the piss out of it. I had to take it easy as I had a new comp. clutch. Also my compression is 135 so Idk what kind of power putting a smaller Hg on would yield. Thanks for your input

[Danger_Dorn]

Lol that 90ft lbs was a typo I meant 80

[AJZax]

on first start up after oil priming system, did you let it get to full operating temp and then dump oil and filter?

Also when you honed cylinders, did you clean the cylinder liners with a brush, soap and water? Did you clean the block oil galleys etc?

Wait with a thick head gasket you're going to drop compression and loose some power there haha. But it shouldn't be THAT much loss of power lol. Who did your tuning?

[kouki_mobster]

run it stock and see what happens

[Danger_Dorn]

Re-torqued the head studs and found out my intake cam was off by 1 tooth advanced. We're snowed in here so I can't run it but I'll update when I can

[Danger_Dorn]

So the power gain was night and day. It pulls much harder now and runs smoothe.