SCCAITS

iTrader: (3)

New motor went to the dyno today and made no power. Builder/tuner nor I can figure out why.

Made 30+ runs on a Dynojet. 90 degress ambient. 180 oil/water. All runs 170-180rwhp no matter what we did to timing/fuel. Max power 180rwhp at 13.5 air/fuel with 27 degrees timing at 7900 RPM. Ran it only up 8500 RPM. But, dual EGT ended up at only 1550 6-8" from flange. Seems low? Never got over 1600.

I made 178rwhp on a Dynojet under similar conditions with a S4/S5 stock port motor with stock S4 ECU.

Motor built to EP specs by a builder.

Basics...
S6 rotor housings
S5 irons
S5 rotors
S6 eshaft/gears
Hurley 2mm seals
S6 corner seals
Comp bearings/oil jets/regulator mod
Large streetport intake and exhaust

Intake...
3.5 custom piping
9" K&N panel filter/box
S5 intakes ported
VDI wired open
5th/6th sleeves/actuators/rods removed
S4 TB/Haltech TPS

Exhaust....
Mazdaspeed Header
ISC front section, 3" mandrel pipe, Dynomax Ultraflo


Spark/Fuel/Management
Microtech LT10
Microtech X4
4 trailing coils
Balanced/blueprinted 460cc injectors/45PSI
Custom 6an plumbing

1. I believe a good EP motor should make 215-230rwhp. Builder/tuner first said at least over 200rwhp for this setup but by the end of the day was saying maybe 180rwhp was more realistic. I call BS. Right?

2. Why are my numbers so pathetically low? What could be wrong?

This is essentially a new build from scratch.

Here's some pics....

BLUE TII

iTrader: (9)

Based on years of trolling this forum the rear wheel horsepower numbers you achieved sound normal to me for a ported S5 on stock manifolds.

Or is there a certain build that you were emulating that has made more?

In EP you are allowed fuel injected but must use stock manifolds OR carbureted and any manifold aren't you?

Is there another team that is competitive using the stock manifold?

From dynos I have seen you will get 20RWHP from a proper short runner intake manifold on your set up with fuel injection and I imagine you will lose a little from that when you are struggling to keep the carb in perfect tune.

This info is just from years on the forum and no actual experience of my own.

cpa7man

iTrader: (2)

I'm a 12a guy, and EGT's for 12a's should not exceed 1600. 1550 is perfect. I've heard 13b's like less EGT.

I wish I could be more help. I only speak 48IDA. It sounds like a solid build for sure.

flaco

iTrader: (7)

i made one for a customer made 181 6port large streetport with s4 internals nothing special and a mt4 microtech so your not that off maybe close to 200 but it should be fun the way you got it

jgrewe

iTrader: (1)

First I would triple check the timing to make sure the Microtech thinks its where you think it is. Next, i would have tried uncorking that intake pipe. You're getting some Helmholz resonance in that pipe, it can be good, it can be not so good, depending on where in the RPM range it occurs. A little bigger may help as well.

Next, the dyno/car set up. Slicks? they'll eat some power on the dyno, get some street tires. Was the car strapped down REALLY tight? That will kill you as well. Always compare only corrected numbers, temp and humidity will suck the power out of your car. Same dyno as the other runs on the other engine? We just had a GT3 car on one Dynojet and it could only manage about 180hp. The same car on a different Dynojet pulled 210! I wasn't there for the 210 runs but the owner is pretty sharp and I would think he's comparing apples to apples when it comes to correted numbers.

All you can do if the vital signs are OK is to take it to the track to see how it runs against other EP cars.

Don49

iTrader: (3)

Prather Racing builds my EP motor and last year at Topeka we saw just shy of 200rwhp during Runoffs week on the Dynojet at the track. This was with a 48IDA and what sounds like essentially the same set up described. I use 2 MSD 6AL's triigered by a 1st gen distibutor 10 degree split and 26 degrees advance. My torque peak was at 7200 HP peak was at 8200 with over 190 from 7200 to 8700 when I shut down the pulls. AF ratio was 12.2 to 12.5 and egt's were right around 1550.

racingdriver

try a cool morning pull or some new plugs. plugs are everything to a rotary.

SCCAITS

iTrader: (3)

Thanks for the replies. I have decided to keep most of the discussion on this motor off public forums and thus have not said much more than the original post. Everything from all looks good to you have a big problem has been heard. Speculation as to why offers many opinions. As of now, no problem has been identified yet and as such no solution.

The next step is a new tune from a different tuner on a different Dynojet. If no meaningful results are achieved by that action, the motor will be shipped cross country for teardown and inspection. Unfortunately the builder/tuner on this motor and I are in disagreement over whether there is an issue and it does not appear we will be working together any longer. No, I am not disclosing a name.

I will offer the following for your pondering. Below is my dyno of a stock 13b. The motor had used S4 housings with stock ports and used S5 rotors. It was a basic rebuild, didn't even have comp bearings. It was built in 1998 but not ran until 2006. Intake and exhaust per ITS rules were used (more restrictive than EP rules). Everything was powered by a 1986 stock computer with a clipped rev limiter. S4 TB with S5 intake and S4 AFM. This motor no longer exists today as it spun a bearing bad so I will post the dyno. It made 177rwhp and 135 ft/lbs torque on a Dynojet.



The dyno from the motor at the center of this discussion is below. Also from a Dynojet, however different dyno, it made 180rwhp and 127ft/lbs torque. While the graphs are scaled differently, take a look at various high RPM points on the curve compared to a stock port stock computer motor. Since this motor will never be raced under these output numbers, the dyno is posted.



As far as dynos, as jgrewe posted he saw 180 and 210 with the same car on different dynos. Another respected racer he also knows, told me he could only get 2rhwp difference when he tried 3 different dynos in town. So, up next is verifying the dyno readings.

speedturn

iTrader: (1)

Dynojet dynos are very sensitive to rotating mass- rotating inertia. Heavier tires/wheels/brakes will lower your calculated horsepower numbers.
Dynojets do not measure torque; they calculate torque based on how quickly you can spin up their heavy inertia roller. They cannot compensate for additional rotating inertia in your car, so if you have heavy rotating parts, your numbers will appear low, even though you may be making higher horsepower. Many years ago, one tuner magazine wrote an article about this, and showed that just by bolting big brake rotors on their car, they lost 8 Dynojet horsepower!

jgrewe

iTrader: (1)

Looking at your dyno charts, one says STD HP the new one says SAE HP. I couldn't find what STD-standard? HP was but I didn't look too long. There are new SAE standards for what size the horses are and how to measure them. Could be a clue, it would be nice if its something as stupid as that.

SCCAITS

iTrader: (3)

Both dynos done on the same tire/wheel combo 15x7 Team Dynamics Pro Race 1.2 and 225/45/15 Hoosier R6. As far as brakes, the new dyno had 2 piece rotors - 3lbs lighter in the front, 2lbs lighter in the rear per wheel. Unsprung weight was reduced with the new dyno vs. the old dyno posted - given that, even more reason the new numbers should be much higher. As far as ambient temps, old dyno at approx 70 degrees, new dyno 90 degrees. The hotter air did not help, but it won't skew numbers that far. Humidity unknown but both days were "sunny". I got about a 6rwhp difference with the old motor with an ambient temp difference of about 30 degrees.

Good observation John. A quick search and STP is also STD. Here's a copy/paste below from the internet. In short, the old dyno may be about 4% high from the new dyno when comparing SAE and STD. It's something, but HP and torque is still awfully low, especially when looked at various points along the RPM range compared to a stock port. I'm going to try and get some more data from the shop on the calculations used in this most recent dyno.

The SAE Correction factor will vary depending on what the temperature and pressure is. So, on a 84*F day (when I did my dyno runs), the SAE correction factor was 1.046. This means I dyno'd 4.6% low (due to the high temperature). Had the temperature been higher, (say 95*F), the SAE Correction would have been say 1.100.

Had the temp been lower, (say 50*F), the SAE Correction would have been say 0.95 - meaning you dyno'd 5% high because it was so cool outside.

Now in each instance, the STP correction factor should be 1.0402 times higher than the SAE correction. Thus the 1.046 SAE turn into 1.088 STP. Or 1.000 SAE turns into 1.0402 STP. Or 0.95 SAE turns into 0.988 STP.

STP will always be 4% higher than SAE. Or you can say that SAE will always be 4% lower than STP. This is just due to the nature of how the two correction factors are defined.

rob81gsl

iTrader: (3)

why were you running such a high afr? from my experience anyways with ida's anyways it seems to make more power in the low 12's......

yallgotboost

Yeah 13.5 A/F is rather high for a 13b from my experience as well. I always got the most power from 12.1 to 12.6.

SCCAITS

iTrader: (3)

My past and current testing showed otherwise. That 177rwhp was at 13.4.

STD vs. SAE had very minor impact. The new dyno converted to STD to match the old dyno changes the max HP to 183.4 and the torque to 129.4 as I went by the dyno shop today and got on their computer and did the actual conversion on this run. Torque is still lower by 8lbs and there is a whopping 5hp gain at max power vs. a stock motor/computer.

Additional research has validated the correct 13b EP rwhp numbers as low-mid 200's (and on stock manifolds). More specifically.. .... not on a public forum.

Booked a different Dynojet today for the 12th and a different tuner to play with the map.

SCCAITS

iTrader: (3)

Bingo. Timing was the major problem. The CAS was off by 5 degrees and the map had been set at 23 with 6 degrees retard, effectively 22 degrees when all said and done at WOT. Why I was told 27 degrees from the last time I don't know, this was not the case.

Fuel was also too rich. I purchased and installed a wideband to have for this tune. We leaned the map out quite a bit. That 13.5 was from a tailpipe sniffer.

Split wasn't bad, we took out 1 degree.

It didn't take long to get peak HP and torque up much higher than the last time by doing some major changes to the map. We did 40 runs to fine tune and really see what could be done.

In the end I now have a completely new map and a car that makes good HP and torque and that also holds for a long RPM band. The peak is not what I wanted nor did we settle with the peak HP map, but rather one that had the most power throughout the range.

The final specs on everything are a mystery. Thanks for all the replies and suggestions.