For most part I agree with you, others dont.

By spraying after the IAT and seeing totally inaccurate charge temps you could never tune in any type of failsafe, crude or otherwise.

 

What would be noted as a discrepancy? Did the IAT readings drop significantly? How much fluid are you spraying? Did you do back to back runs at the same boost level with the alky on/off and record the indicated drop in temp?


The nozzles flow 35gph total at 100psi. They flow more at say 250psi and less at 50psi. ( It's not linear, I have the formula to calculate it if U want I can send it) The pump controller ramps duty cycle up (which raises pump pressure) as more boost as added. The curve is adjusted by the ***** on the controller.

I don’t agree with spraying pre-sensor ever. It depends on the application and how you setup the tune to react. A typical SD tune will never work as it should with massively swinging IAT temps. Sure you can tune around the SD calculations on the VE map at different loads, but that’s not how it was designed to work. Are you using your IAT sensor for primary fueling and SD calculations or are you using it for your meth injections safety system? I don’t see how it could do both correctly? Personally I feel that using it for fuel calculations is more important. As mentioned the sensor is nowhere near fast enough to save an engine in the event of a pump failure. By the time your saturated sensor relays a significant rise in temperature it would be too late to save an engine relying heavily on methanol to keep it out of detonation IMO.

Personally I prefer using actual charge temps so I’m always setup for my “worst case scenario” tune. There will never be a massive fluctuation in IAT’s this way. Closer than they would be if I were using data from a saturated sensor anyway. In the event of a pump failure, my WB02 failsafe would see I was more than a half point off my AFR target and would immediately drop my spark/boost. WB02 is much faster and better failsafe than the IAT sensor.


It’s not so much the octane with alcohol fuels, but the volume of fuel in the CC cooling it. This is why a 100% methanol fueled turbo engine will outperform race gas with a higher octane. So methanol injection in addition to E85 has its benefits IMO. By pulling say 30% E85 from the tune and replacing it with methanol you’ll have a higher volume of alcohol in the CC to aid in cooling, regardless of the octane. The more methanol in the tune the cooler the CC will be and the wider your tuning window will become.

I’m not saying it’s necessary to keep most detonation free, just that it does provide more cylinder cooling.

Most aren’t spraying anywhere near enough to significantly effect charge temps as whole. You are closer to your actual charge temp by using a non saturated sensor.

 

That's why the way Joe explained he is tuning for worst case scenario, with high charge temps and then cooler charge temps via IAT adjust fueling towards where it wants to be with the meth sprayed. So there will be compromises during any transition and some other operating conditions, but it should be reasonably safe.

Ignoring IAT's as you are and allowing them pre-spray....your tuning will always be on the aggressive side as if you lose meth, you've instantly lost the octane and cooling and the ecu has no idea it has happened other than the engine going bang because there will be no change in tuning or IAT whether it's spraying or not.
I just see that as a worst case scenario as far as safety goes.


I dont use either method really, I've different fuel/spark maps for whether I'm spraying meth or not and yes if charge temps do start to rise there will be some "safe" adjustments via IAT, but those would apply whether spraying or not and that approach is fairly generic.
If something did go badly **** up, closed loop correction and knock control would be sufficient to prevent any major damage, but I doubt it would even get that far. Or fractionally slower than that a lean lambda trip would be flagged and again reduce engine rpm and prevent any damage.
So either way I'm well covered.

Obviously factory ecu's and others dont offer people that though

For most part it's only at race tracks or higher grip locations or longer distance racing I use meth anyway. Everywhere else I dont need it or the extra power it can release.

Even at the weekend at a local airfield, warmish day for here and max charge temps I was seeing were around 120degF, that's ramping up to 25psi at end of run
Temps maybe around 80degF at start of run

 

I am not ignoring anything, I am monitoring actual charge temps post IC. I’m not spraying enough volume to significantly impact the charge temps enough to bother altering the tune. (most aren’t) Spraying 12gph pre TB isn’t going to do diddly to my charge temps as a whole or require a massive shift in my tune. Though the plugs prove it cools the CC quite a bit. That’s the purpose with my specific setup.

I understand Ron’s buddy is relying on the methanol, but a WB02 failsafe is a much better method than trying to use a slow IAT sensor as any kind of fail safe. That then frees up the IAT sensor to do its actual job and monitor true charge temps for proper SD calculations.

 

Good discussion.
Sheesh. My head is spinning a bit. :-)
It a pump gas setup. We get 92 here.
I believe Forcefed is correct about the Alky system spraying in relation to boost.
The instructions however were very unclear about what the system is actually doing and how to set it up.

The IAT numbers do seem correct. Early in the day showed ambient at start up. I know these are hardly calibration grade sensors......

I'll see if I can find some real data on these turbos.

BTW, the turbos don't have access to outside air.

It would be great if I had equipment to data log temps pre IC, post IC and in the intake manifold itself to get a handle on what the primary issue is.

 

Feed the turbos cold air.

 

The Cxracing kits I'm aware of come with the baby gt35's. T4 .68 housings and 61/62 turbos. @ 23lbs on a 5.3 I'd bet they are pushing hot air. Figure you're losing at least 3-5psi on the IC pressure drop as well...possibly more. Would be great to see what kind of boost you are making pre IC as well. ($3 peak and hold tire pressure gauges work well for this)

Like these...

http://www.ebay.com/itm/CXRacing-T4-...FS12ZG&vxp=mtr

Seems inline with the twin turbo LS kits cx racing sells as well.

http://www.ebay.com/itm/CXRacing-Twi...FUPz3F&vxp=mtr

 

These are the specific turbos on the truck.

http://www.cxracing.com/mm5/merchant.mvc?Screen=PROD&Product_Code=TRB-T72-P81-R_FLNG-OIL-FEED-AN4&Category_Code=TOCH

 

Shouldn't be pumping hot air then I would't think. Did he actually pop off the cover and measure the wheels? I Believe OSCS just went through this with his 240Z. He ordered 66/65's and they sent 62/65's. Very similar symptoms with the elevated charge temps.

 

I'm sure he didn't measure them.
He also says the IC he chose is only good for 6-700 hp.

 

$3 tire gauge pre IC and a quick comp wheel inspection stat!

IC sounds suspect too. Would be a super cool test to pop that IC off, move the nozzles pre-compressor, and double the meth inj amount. If it has the 72’s on it I bet it picks up quite a bit at the same boost level. Even with lower timing

 

So he measured boost pre IC
Couldn't test higher than 14 psi.
Pre IC was 16 psi.

I would assume this will be worse as boost increases.

 

So 16psi before, and 14psi after ?

It isnt perfect, but it isnt terrible either.

 

It will be much worse at 23psi where he was running it. Why can't he test higher pressures? Were the intake temps even high at 14lbs?

 

It will probably be worse...but really do need to test it.

 

Even with 14" slicks, it won't hook on the street past 14psi.

He can test further when he does license passes.

It doesn't build heat bad at all at 14 psi. I'll review some logs we did.

 

Since we're discussing this IAT issue, I never see IATs anywhere close to this, but in HPTuners I have 'Complex Model' (Cylinder charge temperature) set to enabled so it calculates IAT and ECT to come up with a manifold temperature. I'm not sure if this is how your tune is set up or not, or what best practices are for someone with a relocated IAT (to the charge pipe) even is because we spray methanol just before the IAT which greatly reduces charge temperature.

At 14psi, I'm seeing temperatures no higher than 20ºF above ambient with a CX Racing 31x12x4" IC.

 

To determine if the IC is working well, you'd need to measure temps without any meth acting on the sensor ( and of course if there is any significant pressure drop across it )

 

Might look into a progressive boost control so he can use the car on the street. (sure it will help at the track too) I had the same issue. Now I can run 20+lbs on the street no problem.

 

Sorry I didn't mention I'm not spraying methanol (yet), I was just curious if you all comparing numbers were using the complex style (IAT/ECT formula) or just IAT for your tune and logging.