Where is my top end power?
 

I just did a 1.8 engine swap with flyin miata manifold and I am short of at least 60bhp at the top end. Here's the dyne chart(every square is 25bhp)

https://www.miataturbo.net/attachmen...ine=1315642651

The white line is what my car is doing now and the purple line is another car with the same setup, same engine type. same Garrett turbo (GT2560r), same exhaust, injectors,ecu. The difference are: the exhaust manifold, he is running eBay exhaust manifold and me flyin miata manifold, I am running COP and I am running water injection.

I cannot bring myself to believe that an ebay manifold will make 60bhp more than me!!!

I suspect the following:
- There is something wrong with my exhaust, it collapse or choked
- when rebuilding my head, I got the timing wrong. But my car is idling perfectly and not missing at all, would it still be the case?
- that the eBay manifold is making a lot more power in the top end because it is tubular and the flyin miata ones are log manifold?

Have I missed out anything? Could my engine be fuked? But i am not losing compression, engine oil or coolant and it is holding boost all the way to redline.

Please help.

same exact tune?

Same tuner. I suppose the tune is not far off

your numbers look like torque where his looks like hp...

That's bad...they are both bhp. Mine looks like it is choking at the top end. And I wonder why.

what are the final numbers? and what boost level? and how much water?

the only other time ive seen a HP curve like that is with WI

The final number is a miserable 175bhp on 12psi. I am running the smallest (suppose to be for small engine turbo cars) water injector that came with the aem kit.

It is actually making lesser bhp than my 1.6 prior to the swap.

You described the white line and purple line. What is the green line?

The green line is the same as the white line but with slight differences in my ecu tune.

just to add on another difference, I am running COP and the purple line is not. Would COP makes a difference if not setup properly? I am running dwell of 2.5ms

Here are my thoughts for what they are worth:

1. A tubular manifold will flow better than a log, but not this much better. Remember that the main restriction in the exhaust is the turbo.
2. Make sure of the condition of the intake. Even though you are maintaining boost, your turbo may be working really hard to keep that boost if there is a leak.
3. Do a run without WI using the timing that was used on the other car. It is worth it to eliminate the variable.
4. Honestly, aside from a boost leak, this looks like a valve timing or lift thing to me. Your peak is below 5500. You'll also notice that you're making more power (hence more torque) at the lower RPMs than the other guy. Everything lined up? Cams OK? Lifters OK?

Anyway, just thinking out loud and I'm sure there are things I've missed.

Only if you are misfiring or if you are running a delayed spark advance compared to the other car.

1. A tubular manifold will flow better than a log, but not this much better. Remember that the main restriction in the exhaust is the turbo.
Agreed, thats what I thought too
2. Make sure of the condition of the intake. Even though you are maintaining boost, your turbo may be working really hard to keep that boost if there is a leak.
I also made a run without the airfilter, there is not much difference
3. Do a run without WI using the timing that was used on the other car. It is worth it to eliminate the variable.
Ya I will try that
4. Honestly, aside from a boost leak, this looks like a valve timing or lift thing to me. Your peak is below 5500. You'll also notice that you're making more power (hence more torque) at the lower RPMs than the other guy.

I do not think there is a boost leak because it is maintaining boost level throughout the rev range. Here is my boost chart, the 2nd box is the one, it is holding boost till the end.https://www.miataturbo.net/attachmen...ine=1315669128

Everything lined up? Cams OK? Lifters OK?
Ahh, that is what i need to find out now because I had a headgasket change during the swap. Now, if the cams and lifters are problematic or if not lined out properly, wouldnt there be idling problem or misfiring during high rev?

What are your VE values compared to his with the water injection if you are indeed running the same injectors and req fuel? Just curious. I'm wondering what adding too much water would like like with afr/ve ratio? Would you have to add more fuel to get a burn?

I am running almost the same amount of fuel compared to his. This is a dyno comparison of a 1.6 (RED LINE, before swap) and 1.8 (WHITE LINE after swap) with same water injection setup and same turbo. I was running 14 psi for the 1.6 setup and 12psi for the 1.8 setup.

https://www.miataturbo.net/attachmen...ine=1315669752

Don't discount a boost leak. Your turbo has a fair amount of residual capacity to overcome a leak. But you'll be making it work much harder. The best way to check for a boost leak is to pressurize your intake and do a blead down test.

You do have boost sag. I'm guessing that your signal line for the wastegate is pre-intercooler? Moving it post-intercooler helps.

On WI, don't forget that WI by itself doesn't necessarilly make power. There are two mechanisms at work with WI:
1. "Chemical Intercooling": If you are injecting a good proportion of methyl alcohol, then you should be seeing a fair amount of temperature drop in the intake. That will increase power. If you are injecting 100% water (as I am), then this effect will not be very drastic (or may not be present at all) because the compressed air in your intake is already near the saturation point.
2. "Octane Boost": Adding WI will change the flame-front/pressure-rise properties in the combustion chamber. In this way, it acts like a high-octane fuel. How much of this happens is inversely proportional to your intake cooling. If you use up the chemical cooling in the intake (as you will with more alcohol), then there is less left over for the combustion chamber -- and vice versa. An "octane boost" by itself does not yield increased power -- in fact it can decrease power as it moves the point of maximum cylinder pressure to later in the combustion stroke. I'll bet that the HP curve Brain was talking about was aggressive WI coupled with no change to the spark map. A WI octane boost coupled with an increase in spark advance will increase power. It has to be tuned.

Confused. Different car? This curve doesn't match the original.

Wait, is white line your new 1.8 and red line your old 1.6? That would match.

Yes, my mbad for the mixup. white line is my new 1.8 and red my old 1.6

Probably not. With a 2-valve per cylinder engine, if you had a cam lobe gone or a lifter compressed, you would definitely see it. With our 4-valve engines, you're just increasing overall flow capacity, but it usually won't result in a noticeable miss. Now, if both intakes or both exhausts on the same cylinder had an issue . . . but the chances of that are pretty remote.

Really check the hell out of all your couplers, and make sure your cams are lined up correctly. I had a turbo volvo that did about the same thing, and the cam was off. The turbo would glow red as hell and it would boost fine, it was just down on power. Also, I can't tell you how many times I have just quickly eyeballed all of my turbo couplers and they looked fine at first, then I realized I had a split paralell with the edge of the hose clamp.

Check the cam timing.

On second thought, given the track record of members here recently, photograph the cam timing so WE can check it for you. :)

Oh yeah, no chitty phone pick either.

It was an honest mistake, I swear! :rofl:

It's ok, I thought mine was off since I decided not to plug in my coils. Anything can fuck you.

https://www.miataturbo.net/showthrea...+douche+pickle

If your cams are advanced it will move your torque and hp peaks toward the lower RPM range. I'm going to start there with all other things being equal.

+1 on wanting to see cam gears pics to verify timing.

And mine. Which was caused by boost sag. I had a leak at an injector.

Thanks all. I will get the workshop to check the cam timing again. One of the other variable is my synapse bov. I wonder if it is the culprit.

Is there a cat in the exhaust?

You are not the only person to have cam timing off. Mine was off on my built motor and it took forever to figure that shit out.

If the BOV is leaking you would see the problem down low, while the turbo is still building boost. Once you've hit your desired boost level I wouldn't think it would make much difference.

Updates: We checked the cam settings and timing and it is according to specs. We also checked for clogged exhaust/Cat/flex pipe/resonator and there is nothing wrong with it. I did boost leak check and there a no boost leak.
Giving the benefit of the doubt that the above are not the problem since we went through each item carefully, I will next run the car again on the dyno without water injection.
Will update with my findings.

No cam gear pics? :cry:

Correction: You took forever to fix the issue.

give us the specs on timing water input amount and we can help. Did you check the motor over for a bent rod before you swapped shit out? I know my motor lost alot of power uptop especialy when i had 3 bent rods in it. Lean that damn afr up to 11.5 atleast man 9-1 is not good for making power if i am reading your chart correctly.

- Ran compression test today. Seems healthy across cylinder.
- Switched off water injection, slight difference
- retuned adaptronic ECU, made 30bhp more but I am still down by 30 bhp from another car on the same engine, same turbo, same ECU, different exhaust manifold (me flyin miata and him eBay), i have a visually more restrictive downpipe

Here is the result:
(Red after retune, Blue before)

https://www.miataturbo.net/attachmen...ine=1316245820




(Blue - my current setup, red is the other car on the same setup, pink is before my 1.6-1.8 engine swap)

https://www.miataturbo.net/attachmen...ine=1316245820

I am going to redo and turbo outlet, run 3" till the end and see if it makes a difference.
Just a note, the car runs perfect, no misfiring and idles perfect

Will update after my next change.

dude there are lots of variables that you might be overlooking. things like a messed up compensation factor, humidity, a wacky ems trim etc.

Also, compare your damn timing maps. It may be the same tuner but they may have screwed something up.

It could also be something related to your boost control. One performance tuning aspect that is often overlooked is boost control. Boost control has a HUGE effect on performance. That missing HP could easily be caused by a crappy boost controller or um lazy wastegate or something. Or even a vacuum signal line that is too small.

I appreciate your HP quest, but chasing someone else's dyno graph requires more attention to detail than you are putting in.

Fair enough. You have a point. But the quest is not about chasing another person's dyne map. It's about missing 30bhp from the same setup. Both cars are based on the same ecu base map with the same compensation, trim etc. Dyno environment is the same because it is on the same dyno with the same load/gear/dyno variable.
Like I mentioned previously, everything about this 2 cars are similar, down to the damn vacuum line and even same brand of boost controller(BLITZ to be exact). The only differences are what I mentioned previously in this thread.
I have gone through every variable suggested by good people here and am will try other means. At this point, the purpose of updating this thread so that others can reuse the experience I went through.

I think it looks like a wastegate issue. Are you both pulling your boost control signal from the same location? Before/after the intercooler. Are you pulling your MAP signal from the same point? While on the dyno there was a 1psi difference between where I pull the MAP at the back of the intake manifold, and the front where the tuner pulled it. (could be as simple as different map sensors, but something to think about)

What about the timing and timing trim maps?

I may have missed what type of wastegate you are using, but if the diaphragm inside the can was compromised, it might not be able to hold boost. But you probably have a log to show that it is, so if I think of anything else I'll comment again.

Have you posted up the pics of your downpipe in this thread or only the other one? The downpipe could easily be the limiting factor,
With the wastegate fully open I can imagine the flow right behind the turbine to be pretty turbulent and crappy. Build that new 3 inch exhaust and I bet your power will show up.

Just a quick comment. Notice that your car is making more power sooner compared to the other car with the similar setup. Are you sure your turbos are EXACTLY the same? Same turbine housing? If you had a smaller turbine housing than the comparison car, with everything else exactly the same, this is what you would see. The smaller A/R spools a bit sooner, but the larger makes more power at the top end. For example the GT2560R can be ordered with either a .48 or a .64 A/R turbine housing from ATP.

Also +1 on where you are picking up your wastegate signal line. You should move it to post-intercooler if you have not already done so.

There's obviously a fucking difference between the cars since they don't make the same amount of power. You're not giving us all the important details OP so this thread is 1 star.

I mentioned from the begining of the thread that there are some differences between these 2 cars and I shall list it out again:
- different design turbo outlet pipes (me: seems like it is more restrictive)
- different exhaust manifold (me: Flyin Miata, him: ebay tubular)
- i am running AEM water injection with starting psi at 4psi and ending at 14psi with the smallest nozzle that came with the kit
- I am running COPS but he is not
- wastegate signal is post intercooler from the intake manifold
We are both running the same turbo, both bought new from the same bendor, Nissan Silvia S15 turbo part number 14411-91F00, same exhause(-turbo outlet), same injectors, same intercooler. Both ran on the dyno on the same gear and same dyno settings.

Perhaps, the differences in bhp is because of the difference listed above?

Here's the ignition map, we are running 98 octane petrol here.
https://www.miataturbo.net/attachmen...ine=1316504225

Any real reason why your is map is retared so much above 61kPa?

You are referring to above 61kpa and below 2500rpm or are you referring to across?

If former, it is something i have not cleaned up because the full load dyno rum map does hit that portion of the map.

that timing map sucks.

I run more timing in my 300kpa row than you do in your 200kpa row.

Looks like little timing but timing is relative. I am 10* degrees up in the upper boost levels. Anyway, I think you may be overlooking the effect of a restrictive exhaust. You make more torque sooner and less later.

I think that is true with a non-FI car but not so sure it is true with a turbo car?

I started off with a GT2560 on a stock 1999 engine. When I ditched my factory exhaust and moved up to something larger and more free-flowing, the turbo spooled much sooner and made more power everywhere, including at low RPM. The improvement was dramatic.

Wow, you are running 300kpa?

a restrictive exhaust would spool slower and top end would suffer.\


case and point

https://www.miataturbo.net/attachmen...ine=1316542542

What numbers are you running in your 300kpa row? Trying to gauge when compared to my map.

I run ALL OF IT.

Here ya go. OP's timing map with part of mine. Yes, my timing is pretty darn conservative up there because I only dyno tuned for 24psi. With WI though, I am running 3-5* more timing everywhere except for 4500-5500RPM.

https://www.miataturbo.net/attachmen...ine=1316550129

Makes sense. I'd say you are running 5-7 more dgrees than me at 300kpa

That is the wrong location. Never take the wastegate signal from the intake manifold. Take it somewhere after the intercooler but before the throttle body. You will make much more heat in your inlet air taking the signal from that location. You will also keep the wastegate closed much more often which could restrict flow at higher rpms.

What diameter exhaust are you using? Are you using a cat? What muffler are you using?

If you take it after the IC but before the throttle body your spool will suck dicks because your signal line is so fucking long. This matters when your turbo is larger than a tennis ball

(Posting from my phone.)

:facepalm:

UHM, What? It has been proven here many a time that signal line length doesn't make a lick of difference. Diameter, however, that's a different story. Come on fiance Fae, figure it out.