[KingLT1]

Originally Posted by laynlo15

I agree on the headers since GM really did a good job, screw the exhaust leaks and the smell of no cats. I have that on my Vette and its really bad when I'm on 93 octane this winter. I put in some more E just to rid it of such a bad smell. If I could find a good reliable cat I'd add it. You put your car on a good 17" drag radial, even the 555r2 and you'll probably run in the low 10.40s or may dip into the 30s and you could launch it in 1st gear which I think would pick up your 60ft times.

Agree...but If I was at a prepped track I could probably do that on the 20's. Big difference between a prepped track and a no prep road. Get a Dragy and run your car on a no prep road...you will see what I mean.

[19 2SS]

Just got my car back from CSP as well, only made 553whp with lt4 fuel, csp longtubes and whipple, does the rotofab make that big of a difference???

[Jhunsberger]

Originally Posted by 19 2SS

Just got my car back from CSP as well, only made 553whp with lt4 fuel, csp longtubes and whipple, does the rotofab make that big of a difference???

Are you auto or manual, cat or catless, what size pulley (3.625 probably)?

[KingLT1]

Originally Posted by 19 2SS

Just got my car back from CSP as well, only made 553whp with lt4 fuel, csp longtubes and whipple, does the rotofab make that big of a difference???

Take it to the track or get a dragy and see what it traps before worrying about a dyno number.

[19 2SS]

Originally Posted by Jhunsberger

Are you auto or manual, cat or catless, what size pulley (3.625 probably)?

yeah im auto, catless and 3.625.. how much do you think i'd gain from a big gulp from 553whp? i guess i'd need to get it retuned.. for something like just a big gulp does the tuner need to make pulls on a dyno or is it simple computer changes? idk if its worth it to get it retuned if i just got the car tuned 3 weeks ago. maybe it would be worth doing throttle body and big gulp?

[Joshinator99]

Originally Posted by 19 2SS

yeah im auto, catless and 3.625.. how much do you think i'd gain from a big gulp from 553whp? i guess i'd need to get it retuned.. for something like just a big gulp does the tuner need to make pulls on a dyno or is it simple computer changes? idk if its worth it to get it retuned if i just got the car tuned 3 weeks ago. maybe it would be worth doing throttle body and big gulp?

Definitely low numbers for catless long tubes on a Whipple, but like King said, dyno numbers will definitely vary by dyno brand, calibration, location, altitude etc.

When my motor was stock I put down 590 WHP on a Mustang dyno with stock manifolds and primary cats. That was 3.625 pulley, Rotofab Big Gulp, and 95mm TB (with the crappy 87mm adapter) on 93 octane.

[19 2SS]

Originally Posted by Joshinator99

Definitely low numbers for catless long tubes on a Whipple, but like King said, dyno numbers will definitely vary by dyno brand, calibration, location, altitude etc.

When my motor was stock I put down 590 WHP on a Mustang dyno with stock manifolds and primary cats. That was 3.625 pulley, Rotofab Big Gulp, and 95mm TB (with the crappy 87mm adapter) on 93 octane.

I was expecting around 590whp with my current setup but that didn't happen.. I wish I would have known how well a big gulp works for those with superchargers. It would've been such a big upgrade for such little price but now since its too late i'd be throwing away another grand just to get it retuned so idk if its even worth it

[Joshinator99]

Originally Posted by 19 2SS

I was expecting around 590whp with my current setup but that didn't happen.. I wish I would have known how well a big gulp works for those with superchargers. It would've been such a big upgrade for such little price but now since its too late i'd be throwing away another grand just to get it retuned so idk if its even worth it

Do it when you do your next round of mods. Definitely add a bigger TB and maybe a flex fuel sensor too.

[19 2SS]

Originally Posted by KingLT1

Take it to the track or get a dragy and see what it traps before worrying about a dyno number.

Yeah i'm gonna try to get to a track once these tires come in for the new wheels

[Jhunsberger]

Originally Posted by 19 2SS

yeah im auto, catless and 3.625.. how much do you think i'd gain from a big gulp from 553whp? i guess i'd need to get it retuned.. for something like just a big gulp does the tuner need to make pulls on a dyno or is it simple computer changes? idk if its worth it to get it retuned if i just got the car tuned 3 weeks ago. maybe it would be worth doing throttle body and big gulp?

I think what he is getting at is we were at the same shop, same dyno and same tuner. The difference between you making 553rwhp and mine when it made 620 rwhp is: manual trans (less drivetrain loss), RotoFab dry and a 3.50 pulley. So I think that could make up a lot of your difference.

I don't think the Big Gulp made much of a difference at my power level, maybe after heads, cam and pistons it will.

[KingLT1]

Also keep in mind what gear the pull was made in. 5th gear on a A8 will read 20-25whp low since it's not 1:1. Many shops will not pull a A8 car in 6th because of dyno speed limitations. So a 5th gear A8 pull may read 40-50whp lower then a M6. Another thing is tires...drag radials will dyno 10-15whp less then street tires.

Big gulp for sure requires a retune. The entire MAF curve needs 15-20% airflow added almost across the board. There are spots you have to go back in and add more/less. I picked up some decent power from it...my guess is 20whp based on the fuel I had to give it and the maf flow increase. I gained about 2-3lb/min of air flow and dropped 2 tenths off my Dragy times. I strongly suggest getting a Dragy so you can verify gains when you make changes. It has helped me a ton and super simple to use. You don't need to 1/4 mi pulls if you are not comfortable with that on the street. You can do 0-60, 0-100, 1/8, 1/4, 1/2, 60-130, or even make a custom. The nice thing about it is that it has a verification checker in it so it can not be cheated.

[Jhunsberger]

Originally Posted by KingLT1

Also keep in mind what gear the pull was made in. 5th gear on a A8 will read 20-25whp low since it's not 1:1. Many shops will not pull a A8 car in 6th because of dyno speed limitations. So a 5th gear A8 pull may read 40-50whp lower then a M6. Another thing is tires...drag radials will dyno 10-15whp less then street tires.

Big gulp for sure requires a retune. The entire MAF curve needs 15-20% airflow added almost across the board. There are spots you have to go back in and add more/less. I picked up some decent power from it...my guess is 20whp based on the fuel I had to give it and the maf flow increase. I gained about 2-3lb/min of air flow and dropped 2 tenths off my Dragy times. I strongly suggest getting a Dragy so you can verify gains when you make changes. It has helped me a ton and super simple to use. You don't need to 1/4 mi pulls if you are not comfortable with that on the street. You can do 0-60, 0-100, 1/8, 1/4, 1/2, 60-130, or even make a custom. The nice thing about it is that it has a verification checker in it so it can not be cheated.

Good point on the dyno gear King, you all are a wealth of knowledge! And I am encouraged to hear about your gains with the big gulp. that one was another mod I didnt feel like it was worth it over the RF dry setup.

[KingLT1]

Originally Posted by Jhunsberger

Good point on the dyno gear King, you all are a wealth of knowledge! And I am encouraged to hear about your gains with the big gulp. that one was another mod I didnt feel like it was worth it over the RF dry setup.

No problem! I should add that I did keep my Dry filter when I swapped to the big gulp since it was like new. So I don't know it that helps but I thought the dry flowed better then the oiled?

[laynlo15]

Never a fan of the oiled filter and have always run the dry. It can be over oiled when its time to do that and can cause some issues with the MAF getting oil on it from the filter. King your motor looks real clean, nice set up.