gtistile

Looking to you guys for some assistance in regards to the high MATs I'm experiencing with my new combo. I'm new to the turbo world having come from a 2.9L Whipple combo.

The basics of the setup are:
LC9 Aluinumm 5.3
Forged Rods
Forged Pistons
Stock 317 heads
9:1 Compression
LJMS Stg 3 turbo cam.
LJMS S484 w/ 1.10AR
Holley High Ram
417 Motorsports AIR/Water Intercooler
5 Gallon Icebox w/ Rule2000 In-Tank pump
Holley HP ECM
E85
Manual T56 Trans

Now. First day out at the track I was very pleased, on 17lbs I managed to trap 139mph at 4,000lbs weight, but felt I was being held back on the high end. After reviewing the logs I found that MAT started around 60*, had risen to 140*+ before the 1/8th mile and peaked at 204* going through the 1/4 traps, obviously pulling a LOT of timing out of my already soft tune. I was going through the traps with only 8* of timing.

That said. Why are my MATs climbing so high, and so fast? This was repeatable and consistent and every run had 20lbs of ice in the icebox and verified pump flow and function. Here are a couple of pics, including the location of the MAT sensor which has also been tested and functioning.

Any and all info much appreciated. I need to get this sorted so I can get the rest of my power on gate pressure and then turn up!!!

stevieturbo

I'm more surprised the initial temp seen is so low given sensor location.

Heat soak will be huge there. I can only guess the engine has not been running prior to you racing ? otherwise it would be very unusual for a sensor located in a roasting hot intake manifold to be reading so low, almost ambient ?

gtistile

I mean... I'm not hotlapping the car if that's what you're asking. Ambient was 55-60* or so, and then my thought was the ice in the IC was keeping the airflow over the sensor relatively cool while driving up to the staging lanes, at least that's how it was with the blower combo... This was at a track rental so the car wasn't sitting idle for 30 minutes prior to the runs. Basically drive car up to the burnout box and maybe wait for 1 or 2 cars tops and then go for it...

The MAT sensor has to be in the lower manifold, post intercooler to get an accurate reading...

stevieturbo

It's a hot location for a sensor it will heatsoak there.

For a better picture of how well the system is working, ideally drive along so there is continual cool air over the sensor, engine already warm etc so you can get a proper ambient baseline.

And then run the car under load and see how well temperature responds.

IMO installing the sensor in the charge pipe prior to the TB would give a better picture as it would remove a lot of the heat soak aspect. But if the car is warm and there is a lot of sitting about, perhaps cooling fans on heating up the charge pipe more. Again, there will be heat soak.

gtistile

Cruising at 60mph I'm seeing 100* MAT, not boosting at all. When I downshift to 3rd and go WOT, the log shows the MAT jumping to 135* within 2 seconds. I can't imagine the sensor is getting heatsoaked that quickly with that much airflow happening.

I may have to see if the pre-intercooler charge is super hot to start. Not sure what would cause that either though.

stevieturbo

As said, it's a hot location 100 ambient/baseline seems more reasonable for the location

So a temperature rise of only 35degF seems quite good if that is all it rises ?

gtistile

35* rise nearly instantaneously after I press the throttle is good? I'm pulling timing in under 2 seconds from a 3rd gear roll and if I were to shift and pull through 4th I'd be seeing 200+* And half of my timing table retarded by 7-8*

stevieturbo

If it was instantaneously I'd say there's a wiring fault, the sensors don't respond that fast

gtistile

The sensor is responding correctly. It reads ambient at ambient and rises slowly when I put heat to it with a heat gun to test. The rise in temp is linear and consistent when the car is running and seeing boost, and cools down after I let off the throttle back down to its baseline before the pull in under a minute.

stevieturbo

200degF is pretty horrific.

Either the cooler isnt working or something else is badly wrong.

gtistile

😂 Thats what I've been getting at. All of that is in the original post. I KNOW it's horrific, hence the reason for the post to begin with...

Forcefed86

iTrader: (4)

Nice looking setup!

Bet there isn’t much flow in/out of that core. Faster you can get the water in and out the better the core will work. What are the feed/return diameters? Looks like a lot of “T” fittings and 90* fittings that look good, but don’t flow well.

Have you flowed the system? Get a cheap flow meter and see what that core actually flows the way you have it setup now. I’d redo everything with a true 1” ID piping/fittings. Bet it cools much better… might ask 417 how many GPM it should be flowing.

Also a faster IAT setup with a insulated bung that won't heat soak would be a good idea. Some sort of larger diameter phenolic piece that threads in first, then have the sensor thread into that.


1" PVC hose like this is what I see at out track mostly.

http://anver.com/vacuum-components/v...hs-series/?r=1

Cwarta

iTrader: (12)

Just a random thought, are you positive the sensor reading range is the same as what your using to read it?

JoeNova

Any way to measure water Temps on the cooler outlet?

stevieturbo

Yes..but my point is the numbers make no sense.

A hot engine with a sensor located in the intake manifold simply cannot read only 60degF unless it is a cold engine, or you've been cruising along in cool air and just stopped. But temperatures will rise quickly after stopping.

A sensors reading cannot rise by 35deg instantaneously...simply because the sensors do not respond that fast. Although that has now been corrected as it does rise at a more sensible rate.

As others say, it would be worth monitoring air temp both before and after this cooler...and water temps before and after the cooler to see how well they are pulling any heat and how much heat they are actually dealing with.

Where is your air intake ? is it drawing in hot or cold air ?

Forcefed86

iTrader: (4)

Are the bases of those sensors potted? I'd guess they are designed not to pick up heat from the manifold? If the base is completely insulated form the sensor the numbers seem possible to me with ice water flowing through the IC and very little pressure/flow.

I don’t see a filter on the turbo. Looks like its pulling hot air from right behind the radiator.

stevieturbo

It's installed in a hot environment, one way or another they will get heat soaked whether directly or radiant heat.

No different than sticking your hand in the middle of the intake with a hot engine. It'll still burn lol.


If it is drawing hot air from behind the rad...that could explain a lot.

Forcefed86

iTrader: (4)

The sensor is on the bottom side of an iced intercooler though. If it’s not picking up heat form the manifold, at low pressure/flow with 32* ice water being pumped through the IC at full tilt should easily cool ambient air down to 60* form ambient I’d think. Especially if the intake was relatively cool before a run at the drag strip.

JoeNova

Stop using water and ice in the reservoir.
Dry ice and methanol work so much better.

We used to use them on the dyno to get -50 IATs, because big numbers on pump gas sold more magazines. Had to use cheap Rule bilge style pumps because they didn't last long at 100 below and couldn't justify constantly replacing pumps.

Just don't let track officials see or you are S.O.L.

Forcefed86

iTrader: (4)

LOL thats cool... but sounds scary and impractical! Ethanol wouldn't burn well at those temps either! I bet that core works just fine with proper flow through it. Didn't I hear some craziness about the Rule pumps not flowing under heavy G's recently too?