Stock 4WD RX Turbo Dyno Runs

[Myxalplyx]

Car: 1988 RX Turbo 4WD (Manual)

Place: Xotic Motorsports

 

Just got back from getting some baseline runs on the RX turbo before doing some mods to it. Xotic Motorsports has an AWD dyno so that helped. All dyno runs were (and will be) done in 3rd gear from here on out. There may be some arguments about this but 3rd gear pulls seem to be less straining on my tranny and it goes by quicker. I don't want to pull long dyno runs and have to wait a long time for the car to cool down. Time is $$$ and lately my $$$ have been dwindling. This is still a representation of what the car is putting down to the wheels. It's still good for comparison as mods are done to the car.

 

I let the car cool down until the intake manifold was around 87 degrees on all the runs. Temps where taken with a laser temp probe/light beam the shop has. They aim it at the intake manifold and move it around to get temps. Gas was 93 octane. I did two runs back to back, let the car cool down again and did two more runs.

 

This first dyno plot is with all 4 of the dyno runs that were done. Pics have been made smaller so non-cable modem readers can enjoy them. It may be a little difficult to view though. For the hard of seeing/reading, it's 74.04hp, 79.34hp, 79.24hp and 78.57hp. I should've posted these numbers like this originally. Sorry!

 

 

 

 

 

This dyno plot is the baseline plot I'll be using as a comparison to future mods. It is run #2. Runs 2, 3 and 4 where all pretty much the same. #2 seemed to be in the middle. From here on out, I'll post a hp dyno plot then a torque plot so the lines don't look as confusing running together. This is 79.24hp. It's what I'll use for a baseline for now on.

 

 

 

 

Here is the torque graph of run #2 that will be used as a baseline from here on out. This is 95.19lb-ft of torque. This is what I'll be using for a baseline for now on.

 

 

 

 

All questions, comments and insults are welcome (Well, maybe not the insults).

[Myxalplyx]

*Special Note* I do have an open element air filter on the intake side. Maybe I should've did an absolutely, 100% stock run but this is what's already on it. I apologize for not mentioning this earlier. This air filter is what may be causing the lean running condition post 5500rpm. At any rate, above 5500rpm sucks. Shift early! :-p

 

 

Also, sorry I didn't take any pics or make any movies at the dyno shop. They'll be other times. I forgot my camera.

[JWX]

indeed it does run out of steam above 5500k or so

[maximumBRAT]

Thnks for posting that, i'm not going to shell for a dyno anytime soon, but that is good to know, i was wondreing..

[All_talk]

Great info, its good to have some real test numbers, what’s your mod list, it will be interesting to see how the EA82T responds to them. What’s are typical drivetrain losses for a 4WD car, 25%?? That would put the flywheel HP near rated. Those are good looking curves, that’s a pretty broad, flat torque curve, makes for a nice linear power curve… you gotta love turbo cars. And the A/F looks pretty rich though the boost range, looks like the stock ECU could handle a bit more boost without going to lean Any way to measure/plot EGT on this dyno? That is a pretty sharp drop at 5500 (and you can feel it in the car), I know the heads don’t flow well in the top end, but that seems steep for just a choking VE, could there be something else going on, fuel mapping, the A/F dose seem to move leaner at 5500? Ignition?

 

Again, Great stuff

Gary

[Subi81]

My 86 twagon runs out of steam at 5500 also, just can 't push it anymore, so that curve looks pretty correct to me. Thanks for posting this.

[Subarutex]

How much did that cost on that side of the country? I think over here I would be looking at $150 for the first hour...

[AEIOU]

Did you do the air filter? how hard was it to do, it look pretty much stock, but I can't seem to figure out how to get the stock air box out of my RX. What should I get for parts to do that?

[88rxsedan]

I think thats strange that it has 79 hp,

 

And i remember that drop off after 5.5k, it went away when i emptied the cats and got a high flow muffler

[Myxalplyx]

What’s are typical drivetrain losses for a 4WD car, 25%??

Any way to measure/plot EGT on this dyno?

Could there be something else going on, fuel mapping, the A/F dose seem to move leaner at 5500? Ignition?

Again, Great stuff

Gary

Hello Gary,

 

I'm thinking typical AWD/FWD drivetrain loss is between 25% - 33%.

In this case it's drivetrain loss is 31%

 

There isn't anyway to plot EGT on the dyno however I plan on getting an EGT gauge as one of my first things to do. Everything I do there after would be to try and keep th EGT below what the stock EGT is so as to keep he car running safe. If temps go over, then I know the EGTs are going to high.

 

In this case, I believe the air/fuel ratio is too lean with the open element air filter. It could've easily been tested but I didn't have the stock air filter box with me. At this point, I'd like to get an adjustable fuel pressure regulator to richen things up across the board (Like keeping the a/f ratio around 12.0:1) or so. I'm thinking the a/f ratio got too lean and the car is cutting timing. On run #1, the rpm gauge actually stopped moving just past 6000rpm even though I was still mashing the gas pedal. Not cool!

 

 

 

How much did that cost on that side of the country? I think over here I would be looking at $150 for the first hour...

Subarutex,

Where I go at, it only costs $50.00. It's $40 for 3 runs on the weekend since those are 'dyno days' and tons of people come out. I go by during the week where I can just drive up just about anytime and get as many dyno runs as I want. It's a gold mine of a place until it gets more popular. I encourage any of the Subbie folks in the Delaware/New Jersey/Pennsylvania/Maryland area to stop by.

[Myxalplyx]

I just got finished looking at some old dyno graphs of WJM and Pleiades.

 

WJM:

http://www.geocities.com/wmaham1701/dynoday/pull4_0.JPG

 

Pleiades:

http://www.subaruworld.net/dyno/dyno.html

 

I'm not comparing dyno to dyno because they are different. However, does anyone have an explanation as to the dramatic torque drop just past 5500? It almost seems like fuel is cut or something. I've never seen anything like this before.

 

I know there have been discussion on fuel cut running 13psi+ boost on 87+ year (?) EA82-T's. Is there any discussion on why the power drop off takes place at 5500 so dramatically? I'll keep searching. I know the cams play a part in this but we have a 6500rpm redline. Strange! I'll keep searching.

 

As a reference, here's what happened on the very first dyno run I did. After this particular run, I just shut down between 5500-6000rpm instead of trying to reach the 6500rpm redline.

 

 

[Do It Sidewayz]

Put a good exhaust on there and crank upt he fuel pressure a bit.

 

I had a 1988 RX that would rev to like 7,500 and still make power.

 

your lucky you don't have the crappy 85-86 cams. they were horrible and ran out of steam at 4,500

[88rxsedan]

Put a good exhaust on there and crank upt he fuel pressure a bit.

 

I had a 1988 RX that would rev to like 7,500 and still make power.

 

your lucky you don't have the crappy 85-86 cams. they were horrible and ran out of steam at 4,500

my car is LIGHTLY modded and runs well past 6.5k with no issues, even on high boost, and im not experiancing this fuel cut everyone talks about... even at 14psi, i can run it to the floor all the way to 130 mph (14psi 6.5k rpms), and nothing ever happens

[calebz]

Before I pulled my motor, it started running out of breath just past 6k. This was with the same filter setup Kevin has(except my airbox is completely removed) and stock exhaust.

 

I don't really expect power past 6k with the new motor either.. But I am hoping the TD04 and 2.5 inch turbo back will help with that.. and the higher compression should help with turbo spool. My ideal hope is to make good power from about 2k-5800

 

Side note, Kevin.. what you're feeling is deifinitely not fuel cut.. thats a pretty violent thing.. you'll know it when it happens.. That said, at 12psi, I have never had a fuel cut problem in my wagon.

[Skip]

The reason for the drop off could indeed be the air filter location.

 

I also have temp probes in my air cleaner and

one glued to the inner wall of my throttle body

 

The temp in that location is not favorable for injection of air.

 

The cross over pipe below and the electric fan out put

blows right in it's face.

 

The intake temp could be near 175 deg F

 

couple this with the heating of the air going through

the hot turbo

 

then factor in physics (PV=NRT) you could

be blowing some real hot air in the pots

 

This in turn could lead to knocking and the ECU retarding the timing.

 

My air filter (very similar K&N) is in the inner fender

(see the picture that makes you sick.)

 

6500 is not problem and it feels SOP as it still pulling as

strong as it does at 5000

[WJM]

my stock 85-86 cams pulled better past 4500 than the stock 87+ cams do. That was with an intake similar to Kevins and a stock style exhaust with gutted cats and a 2.5 inch cat back.

 

I do know that stock they stop breathing well at 5500. The ONLY EA82T ive had th freely rev past that is my 89 RX with the delta cams...intake and custom bell mouth down pipe. I reved to 8k with mucho power before I decided its time to shift.

 

I think the MAIN restiction at that 5500 mark is the header. While Pleiades RX was on the dyno, and stuck in that spot where it was 5500-6500....i ventured to stick my hand close to the exh flow out the tail pipe....you would not believe the amount of air rushing out. Then i thought about all that air having to go thru that stock header....

 

After tuning in the timing and a few other things with the new TWE header and DP...the turbo now spool like it used to at around 2400-2600, full boost no later than 2700. Power all the way to 6k no problem. thats when i feel the cams are the limiting factor now, along with the small size of the turbo. Tho I feel the cams are the main restiction in the 6k range.

 

And strangely....out of the 3 RX's Ive had and boosted well beyond stock boost cut...ive never hit the fuel cut.

[Myxalplyx]

The reason for the drop off could indeed be the air filter location.

 

I also have temp probes in my air cleaner and

one glued to the inner wall of my throttle body

 

The temp in that location is not favorable for injection of air.

...........

Good points on the air filter location. I am looking into getting some temp probes as well. Skip, I'll be PMing you about this sometime tonight. This is very important for me to know as well as EGTs. Everything I do at this point on will have a lot to do with EGTs and intake temps. I do not want my intake temps to be anything over stock with future mods.

 

In the meantime, don't forget that on the dyno, the hood is raised and there are two big fans blowing air into the engine bay. Favorable conditions. However, I have a solution (or at least something that could help) with the suggestion you had. I'll be putting on my WRX hood scoop bonnet onto the RX from my Outback Sport. Pics will follow sometime tomorrow. Thanks guys! Great help!