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Discussion Starter #1
Over the winter I changed my set up a little bit. Went from a non intercooled blow through efi throttle body, to port injection with an intercooler. It’s a turbo car. Changed over to Holley efi from fitech. I could not get the car to leave hard at all last year.

1.70 60 ft off trans brake was best time before. Wasn’t spinning. Just sluggish off the line.

this last weekend I was able to take the new set up down the track. 1.56 60 ft was the best so far.

the one thing that I was confused by was the change in mph at the top end. The car overall is faster ET wise. But I was concerned to see it dropped mph.

even at the 330 it dropped .3 so I am thinking the car has so much momentum right away that it’s not on the track long enough to get those same speeds. Not really sure if I’m thinking correct.

the 133.58 run was during colder months and yesterday was in the 90s. I know cold air will help especially a turbo car. Just thought the mph difference was pretty extreme. Haha.

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Discussion Starter #4
Fairly normal to lose some mph at your power level with a better 60 foot. But yours seems excessive. We're air intake Temps alot higher?

it’s tough to say. My previous set up I could never get the data log to work. But being non intercooled before I figured adding an intercooler would lower them. Don’t think they went over like 112ish reviewing my runs from this weekend, even when it was on the dyno and we were tuning, my tuner laughed saying didn’t go over 100 degrees. I guess due to my baby boost Numbers. Haha


I added a stiffer spring in the wastegate for my final run. Added about 2 more PSI. Trapped 104 in the 1/8 and 130 in the 1/4. I was wondering if the added piping and intercooler core was enough of a restriction to slow down air velocity. I’m getting the signal for wastegate from intake manifold so the boost pressure should be the same it was last year I’d think.
 

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Discussion Starter #5
Don’t know if this helps, but if we spun with our Modified cars, we always ran big speed. If we hooked, and had a great 60’ we slowed 2 to 3 mph.
I do remember reading about people saying that exact thing. But before the car didn’t have traction issues. It was a slug out of the hole to be honest. Lol.
 

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.

No clue on turbo cars, but as mentioned, my small tire car always had the best MPH with the slower 60'.
It's like getting a rolling start was my guess.
You're building up momentum while you sit there & spin, and once you get rolling, you gain MPH.


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Discussion Starter #7
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No clue on turbo cars, but as mentioned, my small tire car always had the best MPH with the slower 60'.
It's like getting a rolling start was my guess.
You're building up momentum while you sit there & spin, and once you get rolling, you gain MPH.


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I was thinking that. But the car didn’t spin before. It was a dog out of the hole. I’d say halfway through 1st it just seemed under powered before
 

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Discussion Starter #10
Its kind of like having a looser converter.
With the new set up I was looking over the logs and seeing it drop close to 1000 rpms on a shift. Last year it felt like it only dropped a few hundred.

I’m content with the set up. Just the loss in MPH had me confused. Haha.
 

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Normal, with a slow (usually spinning) start, you get a run at the mph cone. An improved 60' will result in lower et and lower mph. I've gone 9.23 @ 152 spinning (1.33 60') and 8.93 @ 147 ( 1.27 60') on back to back passes.
 

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You lost 5mph on the back half, that 's a ton.
Every incremental after the 60ft you are slower than last year.
You lost power making your changes. Maybe all you ended up with is cleaner running from the hit to 60ft.
Start with MAT or IAT and work from there. You're already hitting your target AFR with closed loop right?
On the plus side, every incremental repeats on those two runs, RT needs a little work tho.
 

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Don't under estimate the power of good air.. It can matter a ton...

When I ran the quarter mile with a PT88 turbo.. The difference in mph from bad air to good, was 156 mph to 162..
 

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Discussion Starter #15
Big drop across the intercooler? Where are you sensing the MAP?
The added two pounds nearly got your power back.
Map is on the back of intake. It’s a Holley hi ram with a provision for the map sensor

yeah adding the 2 lbs it seemed to put it where it was prior or at least damn close.


Before it was a straight shot from turbo to the carb hat. Now it’s got all the necessary bends to plumb the intercooler.
 

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Discussion Starter #16
Don't under estimate the power of good air.. It can matter a ton...

When I ran the quarter mile with a PT88 turbo.. The difference in mph from bad air to good, was 156 mph to 162..
yeah I was thinking it definitely didn’t help that it was probably 30 degrees hotter this weekend and pretty muggy. I have a water meth kit I still have to hook up. Wonder if that will help me with weather like this weekend.
 

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Better 60 ft. times and lower ET indicates that the car is hooking better than before. Lower MPH trap speed may tell you that horsepower output is slightly lower.
 

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Discussion Starter #18
You lost 5mph on the back half, that 's a ton.
Every incremental after the 60ft you are slower than last year.
You lost power making your changes. Maybe all you ended up with is cleaner running from the hit to 60ft.
Start with MAT or IAT and work from there. You're already hitting your target AFR with closed loop right?
On the plus side, every incremental repeats on those two runs, RT needs a little work tho.
The 10.96 run was from last year. The 10.87 run was from this year. Even at the 330 it was .3 quicker this year. Unless I’m misunderstanding what you are saying.
And targets were pretty close on the runs. My 1st run had like 2-3 % closed loop correction in some spots. 2nd run was 1-2%.

As far as the reaction time. Just feeling the car out. Once I figure out staging and launching under boost I’ll know how much time I need leading up until that. I swear I’ve cut a halfway decent light before. Lol
 

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Discussion Starter #19
D6AB0E1C-7151-4CB6-8EE8-2D0EADFB6242.jpeg
This was the run with the 8 lb wastegate spring (vs the 6 lb from the previous runs and previous year)

spun off the line a little and only got one run in with this spring.
Only reason I left this out original post was since I changed boost pressure I thought it was a less fair run to compare.

car definitely doesn’t have the top end charge it did prior. 25 mph vs 30. Wonder if that’s a tuning thing.
Last year I just had timing locked out at 18 degrees. With the Holley we built an actual timing curve. Plugs looked good. And on the dyno adding the last 2 or so degrees of timing picked up a decent amount of power.
 

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Discussion Starter #20
Better 60 ft. times and lower ET indicates that the car is hooking better than before. Lower MPH trap speed may tell you that horsepower output is slightly lower.

reason I was confused was car would always dead hook. Felt like I didn’t have enough power off the line and it just was a slug off the line. Full boost, trans brake, slicks. Best I could get prior was a 1.7 and even after that it just took off slow.
The mph I was concerned about since it was such a drastic difference from last year, and I figured if anything the car should make more power now, feels like it’s making more power, but then the mph says otherwise haha.
 
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