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.

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....

 

ya a streetport should be 200+

 

exhaust backpressure? probably easy to pull an egt probe or o2 sensor...

 

I would check the engine compression first and see where you're at. The egt temps seem a little low as well for a 13.5a/f mixture.

 

Not too familiar with FCs but isn't 13.5 too lean. I second a compression test!

 

egt's do seem a little low for 13.5. Also is your TB ported and polished? I know the FC TB can be a restriction. also compression check is in order. My engine just did 90 warm on all 6 faces and I'm making 190whp @7200 rpm.

 

Thanks for the replies. Compression appears fine. I have ran a ported/polished TB, stock TB, and stock TB with choke plates removed before, no meaningful HP differences. I have decided to keep most of the future discussion on this motor off public forums and thus have not said much more than the original post. It is also in the Race section on this site. 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.

 

I just compared your dyno sheet with the one from my motor done in Topeka last October. In comparison your torque curve looks terrible and is falling off very quickly. I had a peak of 138.2 @7200 and it stayed above 125 until 8300. As a guess it would appear there is a flow problem at high rpm's, although your torque #'s seem low across the board.
Good luck.

 

Thank you for checking and the confirmation on numbers. Not only am I fighting to find the problem but the builder/tuner and I have been fighting over whether a problem even exists. He's out of the equation now.

 

I had a similiar problem with my car. Before I fixed the problem I would describe the problem to feel like I was missing the trailing coil. The car seemed to run OK,,,, but didn't have any torque and would rev OK. I was running a Haltech,, and am getting to know it. My timing was set to 26 degrees @ 4000.

What I didn't catch the first few drives was that my timing split was way off. The trailing was firing as much as 20 ~ 25 degrees split. This trailing spark coming soo late was essentially useless.

Perhaps you have a similiar problem with your trailing ignition. (you didn't mention the settings for trailing)

-Rob

 

That is one of the items on the "suspect" list currently, good point. Honestly I don't know the split and I don't have a Microtech dongle. The builder/tuner used his and we had a falling out so I'm not getting that answer from him. I've ordered a dongle and I'm going back to the dyno next weekend. I'm having another tuner see what he can do before having the motor opened.

 

The only other thing to consider is the incredibly long runners with the stock s5 intake manifold will limit to end numbers. I have heard of guys swapping out s5 manifolds for s4 and seeing an increase as large as 10whp above 7000 rpm.

 

Just set it up to run zero split. Most N/A motors will make more torque with a zero split or most of 2-3 degree split.

 

The root of all evil, with the rotary engine is the exhaust next time you have it at the dyno if there is a flange towards the rear of the car drop it, i have seen unbelievable power drop offs from mufflers. I resently remade my exhaust engine to tip on my 20bpp and made 60hp and i thought the car felt good before this havent been out with it yet.


dave

 

What do you mean by " remade my exhaust engine to tip" ?
What is your current exhaust setup like?

 

^ Too me it sounds like he means header back to muffler end.

 

Yes that is exactly what i meant, sorry i should have said headers to muffler.
And it is very straight, the good thing about exhausts is that if you have a bad one they generally tell you where they are not happy. Discoloration on very hard bends burn marks on very restrictive mufflers. etc etc

dave

 

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. The motor liked 9 the best.

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.

 

I knew those egt temps were too low for that afr reading. Glad to hear you got everything sorted out.

 

well what numbers did you end up with???