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2007 TBSS RWD with some go fast(er) bits.
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Discussion Starter · #1 ·
Just got off the dyno this afternoon, and although the numbers were disappointing, the curves look great and it drives well. Made 337hp and 330tq corrected on a Dynojet 224x. I was expecting quite a bit more from this motor, given the results others have shared on various TBSS forums, but ultimately the dyno is little more than a tuning tool. That's what I keep trying to tell myself, at least.

My truck: 2007 TBSS RWD 83,000 miles LS2 with a C6 oil pan, forged bottom end (LSA rotating assembly with CP Carillo pistons), BTR Stage 2 cam kit, Katech CNC ported 799 heads, TR5 spark plugs.

Other modifications include a PCM of NC stock MAF intake, PCM of NC e-fan kit, FTI 2,800 stall converter, and Magnaflow mufflers welded into the stock catback by the original owner.

If anyone has any insights or suggestions, I'd sincerely appreciate the help! I'm pretty irritated that I put down numbers that bolt on cars regularly put down.
 

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'08 Silver TBSS
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Something does seem off with your power level and mods. First thing I noticed is you're running tr5 spark plugs which I think is too hot. Need to switch to a colder plug like tr6's. You might be having a lot of spark knock retard. Who did your tuning? Might need to find a different tuner.

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2007 TBSS RWD with some go fast(er) bits.
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Discussion Starter · #3 · (Edited)
Need to switch to a colder plug like tr6's. You might be having a lot of spark knock retard. Who did your tuning? Might need to find a different tuner.
Exactly why I included my plugs. I've been seeing that most people are using the TR6, but Mike at Rocky Mountain Competitive Research (the shop that handled the tune) in Colorado Springs said the TR5 would be totally sufficient for my build. Swapping those will be my first step, since there was a "sprinkle of knock through the max torque area," per my buddy who built my engine and was with me at the dyno yesterday.

I'm also concerned that the exhaust is my big restriction. It's totally stock outside of two Magnaflow mufflers in place of the stock resonator and muffler. For the most part it looks sufficient, but the three or so feet of pipe going over the axle is quite a bit smaller than the rest of the system.
 

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2008 TrailblazerSS
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You need a better tuner. I went through 3 tuners until I found a good one. Something def is off with the amount of mods you have listed. I did 373hp and 391tq on basic bolt on’s/ no cam or internals work. Had my truck on the dyno in 2018 before I did super charger and other up grades to see what I gained. I still haven’t been back to dyno since upgrades. Now I’m very curious. I’d def change the plugs to tr6. Some long tube headers and new exhaust might help too.


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2007 TBSS RWD with some go fast(er) bits.
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Discussion Starter · #5 ·
I figured I'd better share the dyno sheet so you guys can get a full picture of the situation. Hopefully this helps. Thanks to everyone who has replied so far!

 

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2007 TBSS RWD with some go fast(er) bits.
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Discussion Starter · #7 ·
What's your altitude? That could be your limiting factor here vs a dyno run at sea level.
I'm a little over 7,000 feet above sea level most of the time. Even so, those are corrected numbers. It really just doesn't make much sense.
 

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Could just be the tune is shit.

After my 402 build the "tuner" decided that 22* of total timing was good, on 10.5:1, and limited the RPM to 6k,.. it was a total slug. Working with someone else now. Great way to waste $600.
 

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2007 TBSS RWD with some go fast(er) bits.
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Discussion Starter · #9 ·
Could just be the tune is shit.

After my 402 build the "tuner" decided that 22* of total timing was good, on 10.5:1, and limited the RPM to 6k,.. it was a total slug. Working with someone else now. Great way to waste $600.
I'll have to look everything over the next time I'm at my buddy's shop. Which will be soon, since it decided it wanted to run extra hot today. Peaked at 235° just sitting in park. Cooled back down to 210° on the interstate no problem, then got back to 220° with some city driving. Gotta double check that the tuner didn't change my e-fan settings.
 

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if the tune was done. with hp tuners post it . I would love to take a look. but from what is sounds like. you may need a better tune.
 

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Discussion Starter · #11 ·
if the tune was done. with hp tuners post it . I would love to take a look. but from what is sounds like. you may need a better tune.
Can do. I'll get it posted up over the next few days.
 

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Discussion Starter · #12 ·
Well, I raced a stock 1999 WS6 with a 4L60 tonight. I had a passenger, he didn't. I pulled on him, slowly but surely. 60-110 and I had about half a car length on him.

Now my dyno number REALLY doesn't make sense. But the truck runs like a dream and seems to pull a little bit harder every day. Gonna swap the plugs, get a 4" MAF and some long tubes, and see where that gets me.

I'll take some logs after the TR6 plugs are in to see what you guys think. Thanks so much for all the input, gents. I'm really liking the community here!
 

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Discussion Starter · #14 ·
At the wheel HP is a lot different than engine HP.
Right. Are you trying to say that 337rwhp on the dyno is different from 337rwhp on the street?

My point, which I guess I should have been more explicit about, is that my 4600lb truck wouldn't have taken a 3500lb F body if I were only making 337rwhp. The power to weight comparison makes no sense with that number in mind. It isn't unheard of for a bone stock WS6 Trans Am to put down 325rwhp...

For argument's sake we'll say he was right at the 300rwhp mark. That means that in order for me to have pulled on him, my truck would have to be above 390rwhp. Obviously there are other factors at play, but power to weight provides a fairly good estimate.
 

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What's your compression ratio and fuel type?
 

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Right. Are you trying to say that 337rwhp on the dyno is different from 337rwhp on the street?
.
No, engine hp will always be higher than wheel hp. You lose power through the drive train drag - converter, trans, drive shaft, rear end, etc)

Your 337rwhp is probably close to the stock LS2 TBSS crank hp of 395 - which is what the manufacturers always post.
 

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10.5:1 on 91 octane. Soon to be re-tuned on 93, and I'll probably do a flex sensor at the same time to further prep for boost.
Budget for larger injectors if you are going to run E85. Even larger if you are adding boost later - think only buy pricey injectors once!
 

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Discussion Starter · #19 ·
No, engine hp will always be higher than wheel hp. You lose power through the drive train drag - converter, trans, drive shaft, rear end, etc)

Your 337rwhp is probably close to the stock LS2 TBSS crank hp of 395 - which is what the manufacturers always post.
Well, if that's truly the case, I just wasted a year of savings on a full engine build at a machine shop to get stock power. Lol cool.
 

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Budget for larger injectors if you are going to run E85.

Fuel pump upgrade and even larger injectors if you are adding boost later - think only buy pricey injectors once!
 
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