420A 420a Turbo goes on the Dyno tomorrow

[DrewmHolland]

Tomorrow morning I'll be posting my Dyno results here on my ebay turbo'd 420a. The motor is built with wiseco 8.8:1 pistons and eagle rods, along with a 0.010" thicker MLS head gasket. I'm running the stock ecu with 24lb mustang injectors and an fmu as well as a walboro 255 fuel pump, my base fuel pressure is 35psi and under full boost it goes to 90. I'm on 9-10psi of boost through a t3/t4 Chinese turbo and an FMIC. I'm also running on 93 octane to prevent detonation. besides boost I have a 25% underdrive pulley and the car is a manual for those wondering. the car drives like a dream and feels dialed in so I'm hoping for good numbers, my guess is 210HP at the wheels!

 

[1990TSIAWDTALON]

Best of luck for numbers you are happy with!!!!

 

[BLACK'98DSM]

There's a ton of variables that go into what that dyno will actually read, but I think 210whp is a little too low for 10lbs of boost. Not by a whole lot though. My guess is 237whp, and if I'm correct you owe me a beer . Also I'm not sure if the car is still with a convertor or not but I'd put a test pipe on it. The result will surprise you being boosted. The stock convertors bottle neck down to about ~1.9" ID and the test pipes usually stay at ~2.25" throughout.

 

[DrewmHolland]

Just got back from the dyno and I made 195hp at the wheels, while it’s less than I expected I was told that most cars make 1lb less boost on the dyno because the wastegate cracks sooner and the graph actually looked really smooth, still I picked up nearly 100hp at the crank and I’m super happy with that. I’m sure a stock 420a would dyno like crap and barely touch 110hp

I’m getting the sheet emailed to me and I’ll post it when I get it

 

[BLACK'98DSM]

That seems a bit low, but I remembered it's the stock ECU. That's your biggest restriction for now. Still not terrible though.

 

[DrewmHolland]

I just hooked up my fuel pressure gauge and realized that I may have been running out of fuel pressure, my target was originally 90-100psi and I was only seeing 80 so hopefully that explains my numbers. I’ve moved the vaccum/boost line for my fmu closer to the turbo and now I’m making 95psi every time so hopefully I get better numbers next month

 

[pat white]

Nothing wrong with that at the wheels for a 420A...and on a stock ecu !

 

[DrewmHolland]

Thanks man, I know it’s not bad for what it is but I feel like the car still has more to give, it’s definitely a lot of fun and I love driving it but I really want to see a clean 200hp so I may just tweak things here and there until I get it

 

[curt-s]

35psi base but 90psi with full boost which is only ~10psi?
Did I read that right?

Rising rate AFPRs are 1:1 with boost pressure above their base, how is the 420A any different? Is it due to the ECU acting ...different... with positive manifold pressure?

Just got back from the dyno and I made 195hp at the wheels, while it’s less than I expected I was told that most cars make 1lb less boost on the dyno because the wastegate cracks sooner and the graph actually looked really smooth, still I picked up nearly 100hp at the crank and I’m super happy with that. I’m sure a stock 420a would dyno like crap and barely touch 110hp

I don't see how dyno or street makes any difference to how the wastegate reacts to signal pressure. Even if somehow it opens sooner because the car is stationary (?), if you're reaching target pressure at your peak, you're still making the same power; it doesn't matter when the wastegate starts opening, only what your peak is.

 

[We're on Boost]

Rising rate AFPRs are 1:1 with boost pressure above their base, how is the 420A any different? Is it due to the ECU acting ...different... with positive manifold pressure?

He's using an FMU which I had to google about cuz I didn't know anything about them either. Still don't know much.
Anyway they aren't 1 to 1. They can be a very much higher rate.
At his target fuel pressures he is going way past the knee in the Walbro 255 flow vs pressure curve. But I looked at that too and if he's only looking for 200 whp, that drop off in flow capability might not hurt him. If it was hurting, he could try to get one of the newer F200003XX type Walbro 255's that are always "not in stock" (6 weeks out) at Summit Racing. F20000312, F20000313, F20000311.

 

[99dsmer4g63]

You are still running the factory fuel pressure regulator that is right beside the fuel tank right? Assuming it’s a 99

My dads 420a we tapped a dedicated boost source for the fmu straight from the manifold. Make sure you don’t have it tee’d into anything, as a failure from something else can cook your car quickly if your fmu isn’t getting correct readings.

Im assuming you have a trusted and functioning wideband in it. I looked at your car profiles but they seemed to not be the one you’re talking about here maybe.

How’s the idle with the mustang injectors?

-Daniel

 

[BLACK'98DSM]

All this fuel talk is why I suggested you getting a wideband gauge a while back. That would truly answer your "I think it's running out of fuel" or "I think it idles rich".
Regardless, I'm ready to see what you make next month and hear what you did to get there.

 

[DrewmHolland]

Ok let me run through my fuel system real quick. Basically I have mustang injectors that flow 20% more than stock, it’s a very mild upgrade so I don’t need a tune to run them however, I did have to delete my original fuel pressure regulator and use my fmu to set a lower base fuel pressure. I’ve noticed that it likes 35psi the most and runs beautifully. When I calculated my boosted fuel pressure I used a calculator from fuel injector clinic since flow from the injectors is not linear, in other words fuel flow at 40psi is about 70% of what it would be at 80psi so you need a lot of fuel pressure to make power. However you also need to factor in manifold pressure since the injectors spray into the intake manifold and need to overcome boost pressure. So if you think you need 80psi but you’re on 10psi of boost then you really need 90. This is why I have to make 90psi of fuel pressure even though I have bigger injectors. The FMU I have is adjustable and will let me change my rising rate to whatever I want, currently it’s about 6:1 but I’ve had it higher and the fuel pump kept up fine. I don’t know what my fuel pressure was because my gauge maxed out at 100psi but it was probably well above that (110-120) and the car pulled decently but the it was definitely too rich and blew black smoke from the exhaust

Sorry Ik it's a lot

 

[99dsmer4g63]

A wideband is an absolute must IMO.

-Daniel

 

[DrewmHolland]

Ik at the very least I need a narrowband, I’m gonna have to get something to watch my afr, I just don’t want to spend like $300 on a wide band rn

 

[We're on Boost]

A wideband is an absolute must IMO.

-Daniel

Yes.

my gauge maxed out at 100psi but it was probably well above that (110-120) and the car pulled decently

How are you logging or seeing fuel pressure? I mean, is it just a mechanical gauge in the engine bay and somebody is there to watch it while your car is running on the dyno?
Hopefully it is an electronic gauge and sensor with a gauge on the dash so you can watch it in the cabin and log it if you have some kind of logger.
Here is the Walbro flow vs pressure chart for the normal Walbro 255 GSS models:

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[jdxnc]

I just don’t want to spend like $300 on a wide band rn

A new motor tends to cost more.

Adding boost to any engine without a way to monitor AFR is just foolish in my opinion.

 

[99dsmer4g63]

Ik at the very least I need a narrowband, I’m gonna have to get something to watch my afr, I just don’t want to spend like $300 on a wide band rn

Do not waste your money on a narrowband sensor. They are pretty much useless. You can use a obd2 scanner and see more than that thing will tell you.

I used a mtx-l for years. IIRC it was around the $200 mark.

-Daniel

 

[DrewmHolland]

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The last pull was done in 3rd gear instead of 4th, I was told by the owner of the dyno that most 4 cylinder economy cars don’t dyno well in 4th gear because you see a lot of extra drivetrain loss, and 3rd gear would be a more accurate result besides the torque.

 

[BLACK'98DSM]

In our transmissions, 4th gear has a 1.03 ratio, while 3rd gear is 1.36. That's why you saw a difference of 47 ft/lbs torque between pulls 2 & 3. The dyno clearly had not been calibrated for this. The results of the last pull aren't an accurate measurement. The higher ratio isn't just a torque multiplier but it will affect the horsepower reading too. Just for fun we've pulled cars in 2nd gear on the dyno being calibrated for a ~1:1 ratio, and it presents stupid high readings. My Prelude had a dyno sheet showing over 350whp/tq, but in 2nd gear. It truly made 211tq at the time with proper calibration and gear choice (4th). You can't just use a different gear and take the readings without a massive chunk of salt. These dyno guys don't sound very educated In fact, there should actually be calibration to account for that extra 0.03 multiplier to get the most accurate measurement.

I was told by the owner of the dyno that most 4 cylinder economy cars don’t dyno well in 4th gear because you see a lot of extra drivetrain loss, and 3rd gear would be a more accurate result

This just doesn't make sense to me at all. You always pull in the gear closest to a 1:1 final delivery (which is 4th gear for the NV-T350), otherwise the calculations are buffed. Deciding to use a different gear mid session just throws away accuracy. There is always a drivetrain loss, which is exactly why the measurement to the wheels is a fair chunk lower than the measurement at a crankshaft. You aren't trying to measure crank horsepower on this kind of dyno though. They're just trying to hype this up, unless they really have no idea how their own machine functions.

Not trying to scold or bicker but I literally said "what the hell" while reading what you posted. That's just strange.

 

[DrewmHolland]

While the torque was definitely wrong I think it makes sense that horsepower would read the same since horsepower is just the total power output your car is making. Basically even though my car was making more torque at the wheels I ended up spinning the dyno slower because of the lower gear ratio. In other words I went from making 180ftlbs spinning the wheels at 100mph to 240ftlbs spinning my wheels at 75mph. The only reason why my hp would change using a lower gear is just the fact that I don’t have to spin the heavy wheels super fast. I hate arguing but I thought about this too much not to share it.

 

[DrewmHolland]

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I thought I'd share this... basically this is how I'm figuring out/guessing my AFR currently. I have 24lb injectors so I subtract manifold pressure from rail pressure and divide that flow rate by 19 (stock injector size) to find out that I'm flowing ~1.85x the normal amount of fuel

 

[BLACK'98DSM]

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I thought I'd share this... basically this is how I'm figuring out/guessing my AFR currently. I have 24lb injectors so I subtract manifold pressure from rail pressure and divide that flow rate by 19 (stock injector size) to find out that I'm flowing ~1.85x the normal amount of fuel

That's fine for figuring your fuel delivery rate, but it isn't safe to assume the AFR. You don't know exactly how much fuel the engine requires under various loads. We used to call that spray n pray. Spray extra fuel and pray it doesn't detonate.

 

[DrewmHolland]

Yeah I know it’s not great, another unfortunate thing about using an FMU is that since injector flow vs pressure isn’t linear, you’ll always be running rich while spooling but honestly I’ve never noticed any sort of bogging or issues even with crazy high fuel pressure. I’ve also been watching my plugs closely for detonation, I saw a some peppering when my old fuel pump was giving up on me and I was boosting it only making like 65psi of fuel pressure but ever since I fixed that it’s been good and I don’t see knock

Obviously my tuning methods are crude but I’m just doing this for fun and I’m not worried about breaking stuff

 

[import solutions]

A wb is just 150 -170
Aem x series or innovate lc2 are good options