Please help me tune my 3.2 Turbo Conversion

[lr172]

Originally Posted by mxessin2

Are you using a stock fuel pump on this build?

Yes, stock pump. I tested by crimping shut the fuel return line. This confirmed the pump could make the pressure, but doesn't necessarily confirm it would deliver volume. Now that I have the gauge in the car, I can ensure that I have steady levels under load. So far, I think it is performing very well.

[lr172]

Ok, shot some pictures tonight. Unfortunately, it is not on the lift so not very good. I'll shot a couple more next time on the lift.

Here are the twins:


Here are some shots of the install:






A little bit embarassing to show the world my aweful welding skills. Also, I wanted to show the routing I used for the oil return, but I can't get the camera under there. I'll post more when I get the Vette off the lift and finish varnishing the kitchen table that I promised the wife I would do as soon as the turbo project was finished.

Tuning is going pretty well. I have a pretty solid 12 into the 5K range, then drop to mid-11's. By 6K, I am in the low 10's. I spoke to Todd today and it sounds like my turbo is a bit choked and won't breath well at the top end. The chip is programmed for more flow at this level and because my turbo won't allow the air to move, it is going rich. This makes sense, as I was expecting a VE issue causing this.

My options are to have him re-map the chip for my flow or to get a bigger turbo. I think I will go the latter route. I currently have a TO4E and appreantly the hot side wheel is too small. He is suggesting a T04B, which is a T4 with a big, higher flowing hot side wheel that won't choke things up a red-line. I found a Garret version (with a T3 flange) with the 60-1 compressor wheel and Stage 3 hot side wheel that flows 60 cubic feet, instead of the 50 cubic feet I have now. Todd is suggesting this shouldn't impact my spool up too much. However, the reason I am at 13 up to 4K is that his chip is mapped for the bigger turbo, which spools up a bit slower. I am on the hunt for a used one and we'll see what I find.

Any suggestions on a better flowing turbo or willing to share what you guys are using?

Thanks again for your help.

Larry

[911st]

Thanks for the pics and congratulations.

Looks like a nice lay out.

What do you think about the difference in acceleration?

Was it worth it?


Sounds like you figured out your on boost AFR variances.

Originally Posted by 911st

...

On boost your system pegs the AFM by 4000rpm and there is no more air flow sensing. Your system becomes 100% a reference system based on RPM only. It will send a given duty cycle signal to the injector at every rpm point no matter what. That duty cycle and the fuel pressure determine you total on boost fueling. (Some adjustment for intake air temp and switching to WOT map.)

Then your system acts as a "reference system" instead of a "sensing system" it has an air flow expectation. (MFI works this way.) If you deviate for some reason from the air flow expectation, your AFR's will not be as expected.

For example, if you have a restrictive air filter or something that slows down air flow, you will still get a given amount of fuel with the lesser air flow and run rich.

Thus, if you can not tune your AFM's using the on boost adjustment on you FPR in a liner manner, you will have to have Proto adjust your chip.

...

[lr172]

Originally Posted by 911st

Thanks for the pics and congratulations.

Looks like a nice lay out.

What do you think about the difference in acceleration?

Was it worth it?

Sounds like you figured out your on boost AFR variances.

Definately worth it. After about 3K, it really improves acelleration; Even more so when the cams come on at 4K. I don't feel it like the 496 in my Vette, which pushes you into your seat, but it is FAST. You get to 120 in no time. A real cool feeling. I think that once I get my boost from .4 to .5 (need a new spring) and free up the top end, it will be quite strong. I am really falling off after about 5500. At 10:1 AFR, you are giving up a lot of power. I would expect peak power to be around 13:1 for this engine. The richer you go, the more you lose, at a surprising rate. Needs to be done to avoid detonation, to a degree.

[911st]

One real expert I believed said we want to stay under an AFR of 11.8/1 on todays street fuel with an EFI 911.

However, Tod has been doing this thing of running boost with high compression and cast piston 911's for a long time. He is in Calif with the junk gas we run so what ever he says would be the way to go I would think.

Keep up the good work.

[Fast951]

Larry, You plan to change the turbo to clean the Air Fuel Ratio?? Have you considered a different solution like a PiggyBack that allows you to tune fuel and ignition to match your car?

[lr172]

Originally Posted by Fast951

Larry, You plan to change the turbo to clean the Air Fuel Ratio?? Have you considered a different solution like a PiggyBack that allows you to tune fuel and ignition to match your car?

Not really changing the turbo to fix the air fuel. I think this turbo spools quickly, but doesn't breath well in the upper RPMs. Todd's chip is designed for a later spooling turbo with more breath (this is why I am lean at 3-4K and rich from 5.5K+). My options are to have him reprogram the chip for my application/turbo or to get a turbo that mathces those characteristics. I was thinking that I may be better off with a turbo that breathes better and gives me more power at the top end. I didn't realize this turbo would run out of gas before red-line. If I do this, I don't need to have the chip re-programmed. This is just a downside of buying a chip from a package without buying the whole package.

The piggyback is a good idea. Please drop me an email with your number. This may be the right time to look into this.

[lr172]

Originally Posted by 911st

One real expert I believed said we want to stay under an AFR of 11.8/1 on todays street fuel with an EFI 911.

However, Tod has been doing this thing of running boost with high compression and cast piston 911's for a long time. He is in Calif with the junk gas we run so what ever he says would be the way to go I would think.

Keep up the good work.

Thanks. I understand the target range to be about 11.8-12.2:1 under boost. I was just indicating that this already under peak and 10:1 is WAY under peak. Todd advocated 12-12.2 at .5 BAR of boost.

The rich AFR is used to reduce the comustion temps, mostly through lower peak cylinder pressure, thereby reducing propensity for detonation. Timing also moves the pressure curve, relative to TDC and has a very large impact on the peak pressure achieved. Essentially the mixture has an impact on the peak pressure (height of the bell curve - Y axis) and the timing moves that curve across the X axis, with TDC constant. The heigt of the curve is really only relevant up to about TDC, generally speaking (seems most measure it at 4* ATDC). After that, the pressure is all goodness. So, detonation control is really a combination of timing and fuel mixture. However, without chip programming ability, we are limited to just mixture.

Hope I didn't ramble too much here.

Larry

[juicersr]

Any updates? Did u reflash the chip?

[lr172]

Originally Posted by juicersr

Any updates? Did u reflash the chip?

Sorry. Haven't been here in a while. Was working a different project. I built a 65 Cobra replica.

I ended up putting in a Megasquirt system to get control over the fuel flow and Advance tables. Worked great and a fun project.

Larry

[cliyde]

Do you still have your protomotive stage 1 chip? I'm in the process of turbocharging my Carrera.

Originally Posted by lr172

Sorry. Haven't been here in a while. Was working a different project. I built a 65 Cobra replica.

I ended up putting in a Megasquirt system to get control over the fuel flow and Advance tables. Worked great and a fun project.

Larry

[viperstang]

was it hard to do the tuning with megasquirt? what plugs are you running?

[drmatera]

Originally Posted by lr172

Sorry. Haven't been here in a while. Was working a different project. I built a 65 Cobra replica.

I ended up putting in a Megasquirt system to get control over the fuel flow and Advance tables. Worked great and a fun project.

Larry

you megasquirted the 3.2? Come on man stop holding out on us.