Power, boost, and airflow

HalfDozIN

Member
Joined
Sep 7, 2021
I typically hate to throw out a generic "wHaT's mY cAR mAke?" post anywhere, because variables are innumerable on a naturally aspirated engine, let alone when you add forced induction to the mix. I am perplexed, though, and think I need help understanding some things. I just joined the board a couple days ago, and just got my T, so I'm still taking my time and getting the basics down. I guess my questions are:
1. A better flowing combo(turbo, intercooler, etc) will make more power at lower boost than a stock combo? Seems sensical to me.

2. I guess, for reference, what kind of numbers have members seen with combinations like mine.
Comp 212 ft, "mild head porting"(no confirmation of that to be true), stock short block, cai w/maf translator, front mount ic, turbonetics 6165, walbro 255 hotwired, 60 lb siemens injectors, and a tt chip. 3400 stall and stock 3.42 gear.

I have spent a little bit confirming some basics like fuel pressure, and I backed the wastegate adjustment off to the base recommended setting I've found (pull rod out about 1/8" to fit over the pin). With good 93, I decided to test some this morning. It makes 13 psi, o2 mv's in the low-mid 800's and zero knock retard which is no surpise at that boost level. What is a surprise is how hard the car feels like it's running. I did figure with all the changes I inherited when I bought it that it would certainly be quicker than stock. At low boost, it feels as though it'd drive away from my cutlass, which runs 8.6 1/8's on 1.9 short times like clockwork. I know that's not blazing, but it's quicker than one of these cars should be at least stock. In short, am I nuts or on the right track here? This car has the potential to move out if my butt dyno is calibrated right.
 

WarWagon

Caustic Cacophony
Joined
Mar 10, 2007
IMO you have incorrect thoughts on your question #1
The stock turbo combo is the one making power at lower boost levels, raising the static compression ratio will make more HP at lower boost.
That combo you mention is probably a low to mid 12 sec range or slower without turning boost up.
Stock heads and even kinda cleaned up heads will still need boost in the upper 20's to get lower ET's
You said car is making 13psi for boost that's weak on a 6165 no alky needed yet.
Turn the boost up!
 

HalfDozIN

Member
Joined
Sep 7, 2021
IMO you have incorrect thoughts on your question #1
The stock turbo combo is the one making power at lower boost levels, raising the static compression ratio will make more HP at lower boost.
That combo you mention is probably a low to mid 12 sec range or slower without turning boost up.
Stock heads and even kinda cleaned up heads will still need boost in the upper 20's to get lower ET's
You said car is making 13psi for boost that's weak on a 6165 no alky needed yet.
Turn the boost up!
Oh I for sure have plenty of room for boost still, just taking it easy. I really thought my change would land me closer to 15, but I got 13. It was making around 19 when I got the car but the scanmaster recalled 2 degrees of kr at some point before me so I backed off. You're saying mid-low 12s at 13 pounds? The car feels about that quick is what surprised me. I didn't expect it to run that well at such low boost.
 

SCOOBY DOO

I'M NOT A MONSTER, I'M JUST AHEAD OF THE CURVE!!!
Joined
Feb 18, 2007
You can run about 15 PSI on 93 safely. Anything more than that and you'll likely see KR if you can't tune. That convertor is to loose for that turbo. 02's in the mid 800's is rich. You're low gear 02's are prolly about the same. You'll need PL to tune it. Info from the ALDL port is slow compared to the ECM. What convertor is in the car...and is it LU or NLU.
 

HalfDozIN

Member
Joined
Sep 7, 2021
You can run about 15 PSI on 93 safely. Anything more than that and you'll likely see KR if you can't tune. That convertor is to loose for that turbo. 02's in the mid 800's is rich. You're low gear 02's are prolly about the same. You'll need PL to tune it. Info from the ALDL port is slow compared to the ECM. What convertor is in the car...and is it LU or NLU.
It is lockup. That is just what I'm told it is. I can tell it's a smaller diameter non-stock converter but I don't have the paperwork for it. It wants to stall around 25-2600 without boost against it.
 

SCOOBY DOO

I'M NOT A MONSTER, I'M JUST AHEAD OF THE CURVE!!!
Joined
Feb 18, 2007
It is lockup. That is just what I'm told it is. I can tell it's a smaller diameter non-stock converter but I don't have the paperwork for it. It wants to stall around 25-2600 without boost against it.
You were told. How many times have I heard that. You need to decipher exactly what you have. I've been at this to long to blow sunshine up your ass. I ain't here to win a popularity contest.
 

HalfDozIN

Member
Joined
Sep 7, 2021
You were told. How many times have I heard that. You need to decipher exactly what you have. I've been at this to long to blow sunshine up your ass. I ain't here to win a popularity contest.
Understood completely. Tires that are on it and brakes won't hold any more on the road, I'm sure there are a couple hundred more rpm in it in a better condition. I'm sure the rich condition is because the chip was burned for more than 13 psi. Pulling it and seeing what information I can get on it from Turbotweak is on this weekend's agenda, and I'm not afraid to order another one if needed. Not trying to pretend I know things I don't, that's nothing but a good way to spend more money. I was just impressed with how it felt even turned down like that, and I'd rather see rich than lean if I had only the two options.
 

WarWagon

Caustic Cacophony
Joined
Mar 10, 2007
Oh I for sure have plenty of room for boost still, just taking it easy. I really thought my change would land me closer to 15, but I got 13. It was making around 19 when I got the car but the scanmaster recalled 2 degrees of kr at some point before me so I backed off. You're saying mid-low 12s at 13 pounds? The car feels about that quick is what surprised me. I didn't expect it to run that well at
This machine needs boost, launch and hook and get at least a 1.8 60ft for mid 12 ET.
 

HalfDozIN

Member
Joined
Sep 7, 2021
This machine needs boost, launch and hook and get at least a 1.8 60ft for mid 12 ET.
Certainly feels stronger than my last 12.60 car did, but feel is hardly scientific. Only one way to know for sure and that's with et. Appreciate the input!
 

SCOOBY DOO

I'M NOT A MONSTER, I'M JUST AHEAD OF THE CURVE!!!
Joined
Feb 18, 2007
That turbo won't light up till 23 PSI. If you're not gonna run it at at least that boost level, then consider going to a stock configuration.
 

HalfDozIN

Member
Joined
Sep 7, 2021
That turbo won't light up till 23 PSI. If you're not gonna run it at at least that boost level, then consider going to a stock configuration.
I'm fine with that, and I'm fine with moving to alky as well. It'll happen at some point, there will just be someone more experienced with tuning these cars than me involved when it does. My experience is with carbureted na stuff. Have a lot to learn for sure.
 

SCOOBY DOO

I'M NOT A MONSTER, I'M JUST AHEAD OF THE CURVE!!!
Joined
Feb 18, 2007
I'm fine with that, and I'm fine with moving to alky as well. It'll happen at some point, there will just be someone more experienced with tuning these cars than me involved when it does. My experience is with carbureted na stuff. Have a lot to learn for sure.
Alky sounds cool. You do realize you'll need several thousand to upgrade the transmission when you add the additional HP.
 

MikeS

Active Member
Joined
Oct 30, 2012
I'm fine with that, and I'm fine with moving to alky as well. It'll happen at some point, there will just be someone more experienced with tuning these cars than me involved when it does. My experience is with carbureted na stuff. Have a lot to learn for sure.
I have a similar combo to you, same turbo- see signature. With a can of VP Octanium added to a tank of 93, and dual nozzle alky, it hits 30psi with no knock, no problem. That turbo is still sleeping at your boost levels.
 
Top