I recently went to the dyno after adding a 2.5 pulley to my 2012 GT500 stock blower car. Only mods are a JLT 123 with the 2.5 pulley. I do have a triple pass H/E that will be going on soon. Temps that day were low 70's 26% humidity. My engine temp was around 165 at start and 195 at end of pulls. IAT2 I believe was max of 120deg. We were using fans on the engine, H/E, and underside of the car. All pulls were done in 4th gear. Any thoughts why it is flat from 5500 deyond. No detonation or knock retard. During most of the pull the knock sensor was adding timing. Base timing I saw was 16 and knock sensor was adding up to 2.25 degrees of timing.
Need assistance with what could be going after dyno
- Thread starter kosovobandit
- Start date
Sorry forgot to add the red line is baseline done in March around same temps humidity was around 60% on the same dyno with just the JLT and different tuner. Not sure who tuner was bought the car with jlt and tune.
Curt@injected
Well-Known Member
Belt slip?
I would not rule out belt slip but I did not hear any audible signs. I'm running a 90mm idler. I was thinking throttle body, spinning the blower too much. Possibly fuel but afr was good. Timing dropped at 5500 plus.
What was the PSI through out the run? If you see it dropping off then that could indicate belt slip.
Your TB could be a choke point with the 2.5 pulley demanding more airflow.
Your TB could be a choke point with the 2.5 pulley demanding more airflow.
Boost was around 13 psi maybe a little higher. Cant trust stock gauge like aftermarket. It didnt fall through the run.
You were making about 35 rwhp throughout the rprm range to about 5,500 rpm, when it just ran out of air. I'd say a bigger throttle body would be in order.
Don't go by the factory gauge. Did the dyno folks put a boost gauge on it for the pull?
Don't go by the factory gauge. Did the dyno folks put a boost gauge on it for the pull?
The company doing the dyno did not put a gauge on it to see the boost. I listened for belt slip based off what I dealt with on my lightning. That this would slip pretty good when the belt got old.
EDIT - went back and looked at my dyno sheets and I did not have that same drop off at 5K. Not sure what is going on with yours.
If youre running the stock TB and the stock exhaust with cats, I think youre just running out of flow ability.
Depending on what you want to do, even an off road H or X pipe will uncork that combo for the stock M122. Its a serviceable unit, but it takes a lot to get more power from it. There is a short list of guys that have gotten M122 powered cars into the 10's.
Do you have any black powdery residue on the snout of the blower? Stock S/C belt tensioners are weak, especially with our cars approaching 8-9 years old now.
Ive got the VMP tensioner and it has noticeably more tension strength than the stock unit.
Id also go with at least a VMP 67mm TB, but until you get those cats out of there your not going to get much out of the M122
Depending on what you want to do, even an off road H or X pipe will uncork that combo for the stock M122. Its a serviceable unit, but it takes a lot to get more power from it. There is a short list of guys that have gotten M122 powered cars into the 10's.
Do you have any black powdery residue on the snout of the blower? Stock S/C belt tensioners are weak, especially with our cars approaching 8-9 years old now.
Ive got the VMP tensioner and it has noticeably more tension strength than the stock unit.
Id also go with at least a VMP 67mm TB, but until you get those cats out of there your not going to get much out of the M122
Stock tune ?
That's about where it runs out of steam.
That's about where it runs out of steam.
Thank you so much for the info. I did notice some dust under the blower on the passenger side of the snout. Car only has 32,xxx miles so never thought of tensioner.
I am running the stock exhaust. Plan on getting kooks longtubes soon and was looking hard at VMP twin 67 mm throttle body.
No it is tuned by a very reputable tuner in the GT500 and Coyote world.
I don't think the stock exhaust is causing any of your problems. There are lots of people running completely stock exhaust from manifolds on back making a ton more power than you are. You might be on the right track with the blower belt though.
I have pretty much your combo currently with a VMP twin 67. I now have a triple pass but when I pulled data logs I didn't so should be close. Max timing shown was at 20 degree, IAT 2 at 109.5, colant at 193F, knock was adding .75 to 1 degree. This was June 6th of this year (72F and 51%RH). How are your plugs? Did you replace/gap/etc when doing the pulley?
Mine, when 100% stock I didn't datalog but it wasn't so flat. I had a bad bank 1 sensor on Driver side when dynoed by VMP at Carlisle. I only made 527/545 and it has that same flat spot which Justin said was due to car going 100% on fuel due to sensor reading lean. So maybe you're just running too rich? But I had light on literally on my way to Carlisle which did point to sensor.
Mine, when 100% stock I didn't datalog but it wasn't so flat. I had a bad bank 1 sensor on Driver side when dynoed by VMP at Carlisle. I only made 527/545 and it has that same flat spot which Justin said was due to car going 100% on fuel due to sensor reading lean. So maybe you're just running too rich? But I had light on literally on my way to Carlisle which did point to sensor.
No worries. I eventually got rid of the 90mm and went with a BPS aux belt idler to make sure belt wrap was never an issue with the new tensioner. Seems to have worked well so far!
Nutty brought up a good point , you need colder ranger spark plugs with higher than stock boost. I cant say enough goof things about the NGK TR7IX plugs. I have mine gapped at .032"
Full Boogie makes a good point about exhaust being able to handle more power. I agree with him when the blower setup is a TVS 2.3L or higher. Just my personal experience with my car set up nearly stock at the moment (TB and Exhaust like you). Its just has no top end when I put the factory cats back in for emissions testing. In my opinion, there just isnt enough huff with the stock blower.
Ive got a home port on my blower along with a Whipple mono and it makes a tremendous difference with off road mid pipes installed. But, its just a bandaid for upgrading to a more powerful supercharger. The headers and 67 will absolutely let a TVS or bigger supercharger make great power while maximizing the potential of the M122.
Thank you everyone. Keep the advice coming. I will replace the belt and tensioner.
The plugs are 3 weeks old and had only been driven on twice before dyno. They are TR6's gapped at .028 as requested by tuner. I sent logs in to tuner and he said this looks normal and if I want more to go to E85.
The plugs are 3 weeks old and had only been driven on twice before dyno. They are TR6's gapped at .028 as requested by tuner. I sent logs in to tuner and he said this looks normal and if I want more to go to E85.
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