carnut169

I took my freshly installed turbo to Dynolab tonight. Goal was to figure out how much boost to run on my stock VVT. Made 6 runs... 1st run was at lowest possible boost- about 9psi and the car made 204hp. Turned it up a little- around 10psi I was making about 220. Next couple runs I hit the fuel cut off in the ms3 which was set at 11, but once I turned that up at 11psi it made 232.4 rear wheel hp (dynojet). The Potato likes to make more psi... sweet spot is closer to 18psi so I better get busy on the motor I've got to build as I believe 300hp is a possibility. On the way back I followed my buddy in his Factory 5 Cobra and was easily able to keep up. 230rwhp is seriously fun. I have no issues with the spool.. it feels really good. Here is a photo of the last dyno run.

Chilicharger665

iTrader: (2)

Your car looks great! Do have a build thread with details on what you've done?

turbofan

iTrader: (1)

Congrats! Numbers look strong. You should post a link to your build thread here. I remember that you had one, but I don't remember what it's called You got it built quick!!

carnut169

No real build thread, but later today I'll post one...

Reverant

iTrader: (10)

Nice nice!

18psi

iTrader: (76)

Great job, congrats, I'm glad you get to enjoy the setup I never got to enjoy when I had it lol

It's just getting started too: you can easily make more than 300 on it once you build the engine

sixshooter

iTrader: (12)

I'm surprised the TQ starts to taper off at 5k. I would have thought a VVT engine and a tater would make peak TQ around 5k to 5.5k, rather than 4.5k. What size exhaust are you using?

18psi

iTrader: (76)

If I remember right he's running either stock or small exhaust.
Also I'd like to see the ignition timing up top.

This powerband is exactly what I was expecting. I like it.

Leafy

iTrader: (1)

That graph looks more like 225hp than 232, you cant count that spike at the end from hitting the rev limiter. The torque doesnt start to taper that bad, and I mean it had to anyways or else he would have had to lower the whole torque curve to stop around 230hp.

carnut169

Build thread:
https://www.miataturbo.net/diy-turbo...5/#post1104648

I am running the FM 2.5 to 3" exhaust. The "stock" map was VERY rich in the high RPM/ load area so I expect this had something to do with the Tq numbers. You can see max HP was actually right after lifting- I was in the 10.5 afr range under full boost at first.

18- I've got the second motor stripped and will be starting on that shortly. It will be tough pulling this motor out as its super entertaining now! Still, 300hp will be even better.

carnut169

Never hit the rev limiter- just lifted around 6500 rpms for the sake of the motor. When your sitting in the seat with the car at 6500rpm and the turbo making all the wonderful whoosh sounds it feels like everything is about to blow up, even when the data is saying your safe. I think the spike is from getting out of full rich settings- it's going to take a little tuning for VEAL to make all the proper adjustments but expect the 230 to be closer to reality. More power is simply a few clicks of the turbo-t away but I'd prefer not to blow the motor.

18psi

iTrader: (76)

Well the 10.5 can easily be raised to 11.5, and post up a screenshot of your spark map and log from the pull and we can give you some pointers. I'd definitely keep it under 250/230 though if you want it to last.

Chiburbian

iTrader: (1)

I know this has been talked about before, but provided the spark timing isn't what is causing the torque to fall off, would it be safe to re-dyno the engine and set the EBC to raise boost starting at 4,500 rpm in small incriments to keep the torque flat at say 220wtq? Obviously this would cause the HP to raise, the question is how much?

That is my plan currently but I need to get a few things dialed in first.

Leafy

iTrader: (1)

On a built engine but 5 speed saver tune, thats how I'd do it. On the stock engine I'd stick with what you have.

Chiburbian

iTrader: (1)

Leafy - I thought it was torque that killed rods? Are we guessing that it is a certain torque at a certain RPM range that kills rods?

I have heard that 240wtq is the max on stock rods, but does that change when you are talking about it across the RPM band? If you stuck the torque at 200-210wtq to redline do you feel like that might be safe with stock block?

(in my case I have a 6-speed)

Leafy

iTrader: (1)

Unlike the tranny, the forces on the rods depend on two things cylinder pressure (basically measured by the torque number) and rpm. Its easier to just give it a hp number. The RPM based forces are exponential, which it why you can nuke a stock rod from just spending a bunch of time above the stock redline on stock power. So the real number you care about, which is cylinder pressure + rpm forces no one has measured or calculated. You can calculate the rpm force pretty exactly and calculate the average cylinder pressure from the torque, and compare that with a bunch of cars that broke... or you could just accept 250ish hp with a normal looking torque curve as the max limit of stock rods.

Fireindc

iTrader: (13)

Woo, looks awesome. Same turbo i'll be running come spring. Get some videos for us, i'd love to see the powerband even at 230whp.

18psi

iTrader: (76)

weren't you the one that kept giving me grief in another thread for saying exactly this?

Leafy

iTrader: (1)

That was for tranny's.