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Discussion Starter · #1 ·
So I'm the one working on the car, here's the breakdown on what's going on, im no over night mechanics, been working on cars for about 15 years, high performance modifications on strictly LS for about 8 years.

Car currently has TSP stage 1 LS3 cam, Kooks 1 3/4" long tubes, full exhaust, Rotofab intake, NGK tr55 spark plugs, Taylor wires, Circle D hp series 2600 stall converter, and a 5th gen Camaro SS 1LE hood scoop


Soooo Sleeper1 brought his 2014 SS in for upgrades which includes

DSX Tuning flex fuel sensor
Granetelli LS7 maf housing
LS7 AC Delco MAF sensor
HPI 80lb injectors

Me and my tuner were trying to get this car dialed in driveability wise before strapping down to the dyno and it would start good when "cold" (under 130 degree IATs), above that it will barely start if even. We would let the car idle with the the hood closed, at about 120 degree IATs the temps would continue to rise 2 degree about every 2 seconds, next thing you know IATs read 174 degree. Which I think is insane, i own a trailblazer SS with an cammed LSA motor, highest IATs in Florida traffic I see are about 120 degree (I know I have coolant cooling the air charge off but still)

Anyway started looking around and finding that it's obvious these cars suffer from heat soak like many GM cars. First things first we try and pull the water deflection tray from the underside of the hood scoop off, which made a huge difference on extracting heat (while moving mainly). Next thing was to see why idle IATs were still climbing high, pulled and found the rotofab intake was missing the heat sheild that is supplied in their kit (T shaped plastic piece that goes on the frame rail) so I went ahead called rotofab and ordered it, but in the meantime I got some DEI heat deflection tape and got it on each side of the frame rail were the box sat. Saw IATs now drop to about 138-145 degree with hood closed. But still having a hard start when shut off then back on. Next thing I find is the radiator upper hose is radiating excessive heat into the maf housing, put some DEI heat reflective material on radiator hose at maf housing, small improvements sitting around a steady 138 degree at idle but some is better than none. But still no start or hard starts.

Last but no least I pulled out my digital infrared temp gun and decided to check individual header runner temps, saw HUGE differences. Bank 1 side averaging 235-280 degree and with a low of 212 degree (cylinder 1) Bank 2 readings were averaging around 230-255 degree with a huge high 375 degree!

While we thought possibly the LS7 maf conversion was getting heat soak and causing our hard start issue we have EGT temps super inaccurate. Has anyone dealt with HPI fuel injectors before, what's everyone's take on this brand, I see on some vette forums people are bashing that brand. Seems like the cooler EGT temps are possibly because of a stuck open injector, high EGT is simply because it not spraying enough.

Going to simply try putting the stock LS3 injectors back in to see if the heat soak affects starting or not. If it starts then we know the injectors are the issue.

Thanks for reading my long post
 

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Welcome to the SS Forums @Ds.motorsports !!!

I will assume that you are asking for assistance with an Aussie Built,,, Holden Commodore based,, SS,, and NOT a Camaro SS!!! You would not be the first and surely not the last,,, to stumble in here from the Camaro camp!! That said,,, ALL are welcome here,,, just the same!!!

ES
 

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Discussion Starter · #3 ·
Welcome to the SS Forums @Ds.motorsports !!!

I will assume that you are asking for assistance with an Aussie Built,,, Holden Commodore based,, SS,, and NOT a Camaro SS!!! You would not be the first and surely not the last,,, to stumble in here from the Camaro camp!! That said,,, ALL are welcome here,,, just the same!!!

ES
Definitely asking about a SS sedan Aussie style lol, I see the red SS sedan as the main picture for this forum. Camaros are boring, I love me a true Aussie car
 

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Are you using a really good temp gun? I've played around doing that on my T/A for verifying I didn't have a dead cylinder with a $50 IR gun, and the temps on even an individual primary will vary 50-100 degrees depending on where I shoot it (at idle btw I find they all usually run around 275-325F). I think either the laser pointer on the temp gun just isn't precise enough for the IR not to pick up stray temps from elsewhere, or perhaps turbulent flow out of the port and the design of the primary can influence where the hot and cool spots are. I've kind of come to the determination it's only useful for telling me if the cylinder isn't firing at all, not really tune variation between cylinders.

It's also known the rear 2 cylinders on most LS's tend to run hot for a variety of theories, one being the intake manifold design and other being the lack of (on most LS's) a rear coolant crossover. Believe most max effort setups will try to tune the rears a tad richer to help keep the motor together. If I remember there's a really good technical thread on LS1tech about it.

It might be better to try something with more precision like a thermocouple to use for data on injector/missfire performance.
 

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Discussion Starter · #5 ·
So we ended up putting the stock injectors back in and it fixed the problem, so I went ahead and ordered authentic bosch 80lb injectors for him.

The HPI injectors suck, 3rd set we find that has issues, definitely would never recommend going through the hassle of buying HPI injectors, itll only leave you dissatisfied
 

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Deatschwerks, or ID.
 
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Eh I’m partial. ID or nothing. They are the pioneers of injector data and testing methods and everyone imitates them and their products. I’m sure FIC are great but I wouldn’t use them.
 
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